Search results for "Ionic"

Novel cationic solid-lipid nanoparticles as non-viral vectors for gene delivery.

2007

In this paper, the suitability of novel cationic solid-lipid nanoparticles (SLN) as a nonviral transfection agent for gene delivery was investigated. SLN were produced by using the microemulsion method and Compritol ATO 888 as matrix lipid, dimethyldioctadecylammonium bromide as charge carrier and Pluronic F68 as surfactant. Obtained nanoparticles were approximately 120 nm in size and positively charged, with a zeta potential value equal to +45 mV in twice-distilled water. Cationic SLN were able to form stable complexes with DNA and to protect DNA against DNase I digestion. The SLN-DNA complexes were characterized by mean diameter and zeta potential measurements. In vitro studies on human l…

Immunohistochemical location of HPL, SP1 and β-HCG in normal placentas of varying gestational age

1986

Sixty-four placentas at various gestational ages were examined by immunohistochemical stains for HPL, SP1 and beta-HCG according to a modified PAP method (Sternberger 1970). Syncytiotrophoblast cell layer was identified as the main site of synthesis. Extravillous immunohistochemical reactions for HPL and SP1 (but not for beta-HCG) were found in X-cells of the basal plate and in the intervillous trophoblast islands. These cell types would thus seem to be derived from trophoblast. Hofbauer-cells of villous connective tissue stained specifically for beta-HCG apparently because of HCG phagocytosis. The intensity of staining for HPL, SP1 and beta-HCG was evaluated semiquantitatively in the syncy…

(H, ρ)-induced dynamics and the quantum game of life

2017

Abstract We propose an extended version of quantum dynamics for a certain system S , whose evolution is ruled by a Hamiltonian H, its initial conditions, and a suitable set ρ of rules, acting repeatedly on S . The resulting dynamics is not necessarily periodic or quasi-periodic, as one could imagine for conservative systems with a finite number of degrees of freedom. In fact, it may have quite different behaviors depending on the explicit forms of H, ρ as well as on the initial conditions. After a general discussion on this (H, ρ)-induced dynamics, we apply our general ideas to extend the classical game of life, and we analyze several aspects of this extension.

Effect of blastfurnace slag addition to Portland cement for cationic exchange resins encapsulation

2013

In the nuclear industry, cement-based materials are extensively used to encapsulate spent ion exchange resins (IERs) before their final disposal in a repository. It is well known that the cement has to be carefully selected to prevent any deleterious expansion of the solidified waste form, but the reasons for this possible expansion are not clearly established. This work aims at filling the gap. The swelling pressure of IERs is first investigated as a function of ions exchange and ionic strength. It is shown that pressures of a few tenths of MPa can be produced by decreases in the ionic strength of the bulk solution, or by ion exchanges (2Na + instead of Ca 2+ , Na + instead of K + ). Then,…

Studies on mechanism and physico-chemical parameters at the origin of the cement setting II. Physico-chemical parameters determining the coagulation …

1996

The physico-chemical parameters determining the coagulation of cements grains previously identified as the first fundamental process of cement setting have been investigated in diluted suspensions using an adapted granulometric method. The analysis of the influence of the ionic concentration in solution on the coagulation reveals that calcium concentration is the parameter which determines the particle interactions. There exists a minimum critical concentration of calcium ions in solution which is required to occur the coagulation of cement particles and a dispersive effect appears for very high concentrations. The results are discussed in relation with DLVO theory and specific interactions.

XPS study of supported gold catalysts:the role of Au0 and Au+? species as active sites.

2006

Gold nanoparticles supported on different oxides (SiO2, CeO2 and TiO2) were prepared by the SMAD (solvated metal atom dispersion) and deposition–precipitation (DP) techniques. The physical and chemical characterization of the catalysts was performed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) and the catalytic activity was tested during the reaction of low temperature CO oxidation. The structural and surface analyses evidenced the presence of small gold crystallites (cluster size ∼2–5 nm) in all the SMAD-prepared samples and oxidized gold species in the case of the DP catalysts. A different surface distribution of ionic gold species was found on the different suppo…

Relationship between structure and CO oxidation activity of ceria supported gold catalysts

2005

Gold catalysts supported on cerium oxide were prepared by solvated metal atom dispersion (SMAD), by deposition-precipitation (DP), and by coprecipitation (CP) methods and were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The catalytic activity was tested in the CO oxidation reaction. The structural and surface analyses evidenced the presence of a modified ceria phase in the case of the DP sample and the presence of pure ceria and gold metal crystallites in the case of the SMAD and CP samples. The DP sample, after a mild treatment in air at 393 K, exhibited only ionic gold, and it was very active below 273 K. By…

Transition Metal Catalyzed Olefin, Cycloolefin, and Styrene Polymerization

2013

The sections in this article are History and Trends Polymerization Processes Supported Catalysts and Morphology Control Polymerization Mechanisms and Stereoselectivity History and Principles of Metallocene Catalysis Regio- and Stereoselective Polymerization of α-Olefins Polymerization of Cyclic Olefins, Cyclopolymerization, and Stereoselective Polymerization of Styrene Late Transition Metal Catalysts Transition Metal Catalyzed Copolymerization Acknowledgements

Synthesis of monodisperse oligomers of ɛ-aminocaproic acid up to a degree of polymerization of 25 by the Merrifield method (1)

1967

Speciation of chitosan with low and high molecular weight carboxylates in aqueous solution

2009

Quantitative data on the speciation of chitosan (310 kDa) with low and high molecular weight carboxylates in aqueous solution are reported. The following carboxylic ligands were considered: monocarboxylate (butyrate); dicarboxylates (malonate, succinate, azelate); tricarboxylate (1,2,3-propa- netricarboxylate); tetracarboxylate (1,2,3,4-butanetetracarboxylate); polyacrylates (2.0 and 20 kDa); polymethacrylate (5.4 kDa). The investigation was performed by potentiometry at t 1/4 25 C, at low ionic strength (without addition of supporting electrolyte) and at I 1/4 0:15 mol L 1 (NaCl). For all the systems the formation of (chitosan)LHi species was found (L 1/4 carboxylic ligand; i 1/4 1 to 4 de…