Search results for "KAO"

Bader's topologycal analysis of teh electron density and the laplacian in kaolinite and dikite.

2009

A new simple approach to evaluate pedogenic clay transformation in a Vertic Calcisol

2006

The aim of this study is to characterize the pedogenic clay minerals by using simple approach: Mixing mineralogical and geochemical findings. The fine clay fractions (< 0.1 μm) of a Vertic Cambisol profile were studied by means of X-ray diffraction (XRD), infrared spectroscopy (FTIR) and cation exchange capacity (CEC). Qualitative and quantitative mineralogical compositions of the clay mixture were determined. Moreover, chemical equilibria and thermodynamic stabilities of minerals (calcite, gypsum, kaolinite, smectites and illites) were studied using results of ionic activities obtained from total concentration of various aqueous species in water extracts from soil-saturated pastes. XRD ana…

Origin of clay minerals in soils on pyroclastic deposits in the island of Lipari (Italy)

2005

The island of Lipari (Italy) is characterized by calc-alkaline to potassic volcanism and a Mediterranean-type climate. The mineralogical and chemical features of two different soil profiles with ages of 92,000 and 10,000–40,000 y, respectively, have been investigated. There were no Andisols, but Vitric and Vertic Cambisols have developed at both sites. Although the morphology of the soils was similar, remarkable differences in the clay mineralogy between the two sites were observed. The site with the Vitric Cambisol was associated with the weathering sequence: glass → halloysite → kaolinite or interstratified kaolinite-2:1 clay minerals. Both sites had smectite in the clay fraction and, to …

Geochemical characteristics of waters in mineralised area of Peloritani Mountains (Sicily, Italy)

2009

Abstract This paper presents the results of a study on the geochemistry of waters circulating in the mineralised area of the south-eastern sector of Mt. Peloritani (north-eastern Sicily, Italy), aimed at basic understanding of the geochemical processes influencing their chemical composition. Chemico-physical parameters and data on 26 major and minor chemical elements are reported for 103 water samples. Water chemistry is mainly dominated by dissolution of carbonates and hydrolysis of aluminosilicate minerals. Total dissolved salts (TDS) range from 80 to 1398 mg/L. All the waters exhibit E H characteristic of an oxygenated environment. Excluding two samples, which show very high H + activity…

Isomerization and redox tuning in ‘Maya yellow’ hybrids from flavonoid dyes plus palygorskite and kaolinite clays

2014

Abstract The composition of the organic fraction of organic–inorganic hybrid materials prepared upon attachment of different natural, ‘historical’ flavonoid yellow dyes (zacatlaxcalli, fustic, marigold and cosmos) to palygorskite and kaolinite clays is described. Upon thermal treatment between 100 and 180 °C, significant isomerization and oxidation reactions occur thus resulting in the formation of polyfunctional materials potentially usable for therapeutic, catalytic and art purposes. The dye attachment to the clays would define a ‘Maya chemistry’ whose complexity could explain the versatile use of such materials in the pre-Columbian cultures.

Chromium liquid waste inertization in an inorganic alkali activated matrix: Leaching and NMR multinuclear approach

2015

A class of inorganic binders, also known as geopolymers, can be obtained by alkali activation of aluminosilicate powders at room temperature. The process is affected by many parameters (curing time, curing temperature, relative humidity etc.) and leads to a resistant matrix usable for inertization of hazardous waste. In this study an industrial liquid waste containing a high amount of chromium (≈ 2.3 wt%) in the form of metalorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid ha…

Chiral approach to antikaon s- and p-wave interactions in dense nuclear matter

2006

The properties of the antikaons in nuclear matter are investigated from a chiral unitary approach which incorporates the s- and p-waves of the ${\bar K}N$ interaction. To obtain the in-medium meson-baryon amplitudes we include, in a self-consistent way, Pauli blocking effects, meson self-energies corrected by nuclear short-range correlations and baryon binding potentials. We pay special attention to investigating the validity of the on-shell factorization, showing that it cannot be applied in the evaluation of the in-medium corrections to the p-wave amplitudes. In nuclear matter at saturation energy, the $\Lambda$ and $\Sigma$ develop an attractive potential of about -30 MeV, while the $\Si…

The nature of Lambda (1405) hyperon resonance in chiral dynamics

2010

10th International Conference on Hypernuclear and Strange Particle Physics. Tokai, JAPAN, SEP 14-18, 2009

s-wave charmed baryon resonances from a coupled-channel approach with heavy quark symmetry

2009

We study charmed baryon resonances which are generated dynamically within a unitary meson-baryon coupled channel model that treats the heavy pseudoscalar and vector mesons on equal footing as required by heavy-quark symmetry. It is an extension of recent SU(4) models with t-channel vector meson exchanges to a SU(8) spin-flavor scheme, but differs considerably from the SU(4) approach in how the strong breaking of the flavor symmetry is implemented. Some of our dynamically generated states can be readily assigned to recently observed baryon resonances, while others do not have a straightforward identification and require the compilation of more data as well as an extension of the model to d-w…

Properties of D and D-* mesons in the nuclear medium

2009

We study the properties of D and D-* mesons in nuclear matter within a simultaneous self-consistent coupled-channel unitary approach that implements heavy-quark symmetry. The in-medium solution accounts for Pauli blocking effects and for the D and D-* self-energies in a self-consistent manner. We pay special attention to renormalization of the intermediate propagators in the medium beyond the usual cutoff scheme. We analyze the behavior in the nuclear medium of the rich spectrum of dynamically generated baryonic resonances in the C=1 and S=0 sector and their influence on the self-energy and, hence, the spectral function of D and D-* mesons. The D meson quasiparticle peak mixes with Sigma(c)…