3,197 research outputs found
On the detection of bioplastic content in marine water using analytical and spectroradiometric techniques
No full textResponse of Sabella spallanzanii to multiple stressors. The combined effect of infection and copper sulphate
No full textThe aim of this work is to study the immune responses of the polychaete Sabella spallanzanii after exposure to
copper sulphate, an immunomodulating agent in marine organisms, and the multiple stresses caused by
Escherichia coli infection, to validate the species as a model organism in marine-coastal biomonitoring programmes.
Polychaetes were housed in laboratory and divided into five experimental groups: 1. Control (no
microinjected), 2. filtered seawater + TBS injection (control of point 3), 3. filtered seawater + E. coli injection
(control of point 4), 4. CuSO4 + TBS injection (control of point 5), and 5. CuSO4 + E. coli injection. The immune
variables, esterase and alkaline phosphatase activity, cytotoxicity and detoxifying/antioxidant enzymes such as
glutathione peroxidase were evaluated in total body extracts of the animals. Moreover, toll-like receptor, allograft
inflammatory factor-1, lysozyme and haemagglutinating activity were investigated to highlight possible
interactions. Indeed, the results of this work demonstrate the immunomodulating effect of copper sulphate on
S. spallanzanii total body extracts related to oxidative stress and inflammatory markers
Voltammetric Investigation on Uranyl Sorption by Alginate Based Material. Influence of Hydrolysis and pH Dependence
No full textThe removal of U(VI) as uranyl (UO22+) from aqueous solutions was investigated by sorption onto alginate based material. The hydrolysis of uranyl ion was always taken into account in the calculations of free (22UO) ion in aqueous solution, in the experimental pH range considered, as well as the acid-base properties of alginate polymer. The sorption process follows a pseudo-second order kinetic model and the sorption rate decreases when the pH value increases. In addition to the classical Langmuir and Freundlich models, the equilibrium data were fitted by using a modified multi-component equilibrium model, never tested before. Differential Pulse Voltammetry (DPV) and
Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) measurements were carried out in NaNO3 aqueous solutions for the kinetic and equilibrium studies, respectively. Direct measurements of uranyl by DPV
were carried out without using complexing agent, as usually reported in the literature; this allowed us to know the free
UO22+ concentration and the hydrolyzed species formed in the ~ 2.0 to 5.0 pH range investigated. The physical structure and morphology of biomaterials was investigated by Scanning Electron Microscopy (SEM) analysis and Energy Dispersive X-ray spectroscopy (EDX) measurements
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
EFFECT OF IONIC STRENGTH AND MEDIUM COMPOSITION ON THE REMOVAL OF Pb2+ BY ALGINATE GEL BEADS. DPVASV AND ICP-OES MEASUREMENTS.
No full textThe biosorption, i.e. a passive sequestering process by metabolically inactive biomass, shows a growing interest for toxic metal ions removal from contaminated aqueous solutions (1), such as municipal and industrial wastewaters. Since the sorption mechanism occurs mainly by ion exchange between the metal ion present in solution and the counter ion of the biopolymer (2), the efficiency of the sorption process largely depends on ionic strength and on the medium composition of solution containing the metal ion to be removed. In order to evaluate quantitatively the influence of ionic strength and medium on the metal removal process by the biomass, we
report here results of a study on the sorption capacity of calcium in gel phase toward Pb2+ in aqueous solution in different simple (NaCl, NaNO3) and mixed [NaCl+CaCl2, NaCl+MgCl2, NaCl+Na2SO4) ionic media, in a
wide range of ionic strength (0.05 < I/mol L
-1 < 0.8), and at room temperature. Investigations were performed by evaluating the Pb2+ concentration in the solution after adsorption onto different amounts of calcium alginate gel beads over continuous time. Measurements of Pb2+ concentration were carried out by Differential Pulse Anodic Stripping Voltammetry (DP-ASV) and by Inductively Coupled Plasma Optical Emission Spectroscopy ICP - OES. To avoid the hydrolysis of the of Pb2+ ion, the solution containing the metal ion to be removed was kept at pH ~ 5. The pseudo second-order model was used to fit sorption process kinetic data(3). Sorption equilibrium was analysed using Langmuir and Freundlich isotherm models. Although both isotherm equations fitted properly the equilibrium data, Langmuir model seems to fit data slightly better than the Freundlich model
Studio delle proprietà acido-base del chitosano in soluzioni acquose di NaCl e interazioni con leganti carbossilici, a 25°C.
No full textAqueous solution chemistry of alkyltin(IV) compounds for speciation studies in biological fluids and natural waters
No full textOrganotin(IV) cations behave as Lewis acids of different strength depending on the charge, according to the following acidity scale: RSn3+ > R2Sn2+ > R3Sn+. For this reason they can react with Lewis bases containing –O, –N, –S donor groups to form complex species of different stability. Complex formation of organotin(IV) moieties with a great number of inorganic and organic ligands in aqueous solution is reviewed here in the light of their environmental and biological impact. To this end, complex
species formation was considered in different ionic media and at different ionic strengths, with reference to the composition of natural waters and biological fluids. In particular, the interaction of alkyltin(IV) compounds with the following ligands was taken into account: hydroxo, chloride, sulfate, fluoride, carbonate and phosphate; carboxylates, amines, amino-carboxylates, nucleotides, saccharides, S-containing ligands and antibiotics. Moreover, the interaction of organotin(IV) cations with synthetic (polyacrylate) and natural occurring (fulvic and alginic acids) polyelectrolytes was also considered. The
strength of interaction is reported in terms of stability constants of complex species formed and of other thermodynamic parameters, such as formation enthalpy. The stability trend of the complexes is
alkyltin(IV)-S > alkyltin(IV)-N > alkyltin(IV)-O-donor ligands. On the basis of data in the literature, empirical relationships are provided to predict the stability of alkyltin(IV) species with some classes of ligands. The complexation models proposed by the different authors for the species formation of mono-, di- and tri-alkyltin(IV) in the presence of various ligands were considered in the light of defining the speciation picture of this class of compounds in aquatic systems
Study of [2-(2’-pyridyl)imidazole] complexes to confirm two main characteristic thermoanalytical behaviors of transition metal complexes based on imidazole derivatives
No full textImidazole derivative ligands are recognized as useful models for biomimetic complexes. Among
the inorganic–organic hybrid complexes, those with derivatives of imidazole heterocyclic N-donor
ligands are interesting for their framework. In previous studies of complexes with imidazole
derivative ligands, our group reported two main thermally induced decomposition behaviors
supporting two different systematic decomposition trends. In this work, one of these characteristic
decomposition mechanisms was again found. The final goal of these serial studies is the possibility
to provide, by the experimental evidences, a prediction model of thermal stability and
decomposition typical behavior by comparing the structural characteristics of a precipitated
complex.
2-(2’-pyridyl)imidazole complexes with transition metal ions of general formula M(PyrIm)2(H2O)2
(where M = Cu, Zn, Cd, Mn or Co) were synthesized, characterized and studied by thermoanalytical
techniques coupled to mass spectrometry, to suggest their decomposition mechanism by evolved
gas analysis (EGA-MS).
Complexes also showed the interesting possibility to be precipitated with two methanol molecules
in the structure and to replace methanol molecules with water molecules under controlled
conditions
Untreated <i>Opuntia ficus indica</i> for the Efficient Adsorption of Ni(II), Pb(II), Cu(II) and Cd(II) Ions from Water
No full textThe raw cladode of Opuntia ficus indica (OFI) was evaluated as a sustainable biosorbent for the removal of heavy metals (Ni, Pb, Cu, and Cd) from aqueous solutions. The functional groups of OFI were identified by employing DRIFT-FTIR and CP-MAS-NMR techniques before and after contact with the ions in an aqueous media, showing a rearrangement of the biomass structure due to the complexation between the metal and the functional groups. The adsorption process was studied in both single- and multi-component systems under batch conditions at different pHs (4.0, 5.0, and 6.0), different metal concentrations, and different biomass amounts. The results show that the raw OFI had a removal capacity at room temperature of over 80% for all metals studied after only 30 min of contact time, indicating a rapid adsorption process. Biosorption kinetics were successfully fitted by the pseudo-second-order equation, while Freundlich correctly modelled the biosorption data at equilibrium. The results of this work highlight the potential use of the untreated cladode of OFI as an economical and environmentally friendly biosorbent for the removal of heavy metals from the contaminated aqueous solution
- …
