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Impose Pressure and Change Technology: Pressure-induced intrusion and organized nanostructures in zeolites
No full textPolychrome Mediterranean vessels and beads: exchanges in western Mediterraneran area during Iron Age
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Effect of oral chronic isoflavones supplementation on male rat sexual performances and sexual hormone plasma levels
No full textThe aim of our study was to evaluate how a chronic isoflavones oral supplementation could affect male rat sexual behavior in relationship to cause eventual change in plasma sexual hormone concentrations. Isoflavones were administered in the form of a standardized dry extract of soybeans. Three groups of 20 sexually experienced male rats were consecutively treated with saline 2 ml, or isoflavones 0.4 mg/kg(-1) or 0.8 mg/kg(-1) soybean dried extract via gastric tube for 40 days. No significant differences were found as regards sexual performances of the three studied groups at the baseline levels nor at the end of the study: in relationship to the base-line value, only mount frequency increased in the control group (z = -2.047, p = 0.041), while intromission frequency in the high dosage isoflavones group (z = -2.484, p = 0.13). At the base-line test 23.08\% of rats in each group were not able to conclude their performance in the standard time, while at the end of the study only 15.38\% of the control group rats were not able to do this. No significant difference has been observed as regards FSH, progesterone, androstenedione plasma levels, either between groups or between baseline and study end. Slight differences were found regards LH and testosterone plasma level
High-pressure behavior of high silica ferrierite
No full textFerrierite (FER framework topology) is a well-known
aluminosilicate zeolite mineral. An understanding of the structure and
properties of FER remains important because of its role as a catalyst in
commercial reactions. For example, it is important in the petrochemical
industry, where it has been used as a shape selective catalyst for
the production of isobutene. The thermal behavior of this phase (in
its high silica form) was recently studied by Bull et al [1], while its
compressibilty has never been investigated before.
The high pressure (HP) behavior of synthetic high silica zeolite
ferrierite (FER) was investigated by means of in-situ synchrotron X-ray
powder diffraction, with the aim to understand the P-induced deformation
mechanism. The microporous material was sinthesized starting from
pure silica and pyridine and propyl-amine as structure directing agents.
Here we report the preliminary results on the compressibility of the as
synthesized phase. The study of the compressibility of the calcined one
will be carried out in the following steps of the project.The crystal structure of ferrierite is built up of rings of fivecornershared
SiO4 tetrahedra (known as five-membered ringsor 5MRs)
building units, which form layers in the ab plane.The layers are
connected to form a matrix of 10MR channels running parallel to the
c axis, which are intersected by 8MR channels running parallel to
the b axis. Six-membered rings connect the 10MRs alongthe c axis
direction.
The HP diffraction experiments were performed at BM01a beamline
(ESRF), at the fixed wavelength of 0.71 Å, using a modified Merril-
Basset DAC and a mixture of methanol- ethanol and water (16:3:1)
as penetrating P-transmitting medium. The powder patterns were
collected from Pamb to 6.2 GPa. Some patterns were also measured
upon pressure release up to Pamb, to check the reversibility of the
compression effects. The unit cell parameters were refined by means
of Rietveld method.
The main results of this study are:
1) No complete X-ray amorphization is observed up to about 6.6
GPa;
2) No abrupt change of the elastic behavior is observed in the whole
pressure range. Between Pamb and 6.2 GPa the reduction of the
cell parameter are 4%, 5% and 6% for a, b and c respectively,
accounting for a volume reduction of about 14 %.
3) The bulk modulus obtained using a second order Birch-Murnaghan
equation of state and data weighted by the uncertainties in P and
V was K0 = 30.1(3) GPa. This compressibility determined in
m.e.w. is one of the highest when compared with other natural and
synthetic zeolites studied with “penetrating” aqueous media [2],
[3].
4) The P-induced effects on as-syntehsized ferrierite structure are
completely reversible
ELASTIC BEHAVIOR OF ZEOLITE BOGGSITE IN SILICON OIL AND AQUEOUS MEDIUM: A CASE OF HP-INDUCED OVER-HYDRATION
No full textThis paper reports the results of an in situ high-pressure synchrotron X-ray powder diffraction investigation on the natural zeolite boggsite [(K0.06Na0.36Sr0.01Ca7.00Mg1.20)(Al17.52Si78.62Fe0.05O192)·82.3 H2O]. The study was performed using both a (16:3:1) methanol:ethanol:water mixture (m.e.w.) as a nominally “penetrating” hydrostatic P-transmitting medium and silicon oil (s.o.) as a “non-penetrating” medium. The studied pressure ranges are: Pamb–7.6 and Pamb–5.9 GPa in m.e.w and s.o., respectively. No complete X-ray amorphization is observed up to the highest investigated pressures, and the original unit-cell parameters are almost completely recovered upon decompression in both media. The reductionsof a, b, c, and V, within the pressure-ranges investigated, are 5.3, 4.2, 4.0, and 13.0% in s.o. and 4.1, 4.1, 3.8, and 11.5% in m.e.w. The Rietveld structural refinements of the powder patterns of the experiments in m.e.w. converged successfully up to 3.6 GPa and demonstrated the penetration of 13 additional water molecules between 0.3 and 2.9 GPa. This over-hydration occurs without any unit-cell volume expansion and can be explained by the fact that no new extraframework sites arise during compression and that water penetration is the only factor to increase the occupancy of already existing sites. Boggsite compressibility is higher in s.o. than in m.e.w. In particular, compressibility in m.e.w. is lower below 3 GPa, whereas above this pressure, the P-V trend becomes similar in the two media. This can be ascribed to the fact that, during water molecule penetration (0.3 < P < 3 GPa), the effect of the P-transmitting medium is directed to compress the system as well as to penetrate the channels
Pressure-induced supramolecular organization in microporous materials: the case of all-silica ferrierite zeolite
No full text“Ab-initio” structure solution of natural and synthetic zeolites by Automated electron Diffraction Tomography
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