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21.
The mechanism of formation of zinc ferrite (ZnFe2O4) from ZnC2O4·1.8H2O-2FeIIC2O4·2H2O and ZnC2O4·1.8H2O-Fe2III(C2O4)3·6H2O mixtures is investigated. By combination of TG and XRPD measurements it has been shown that microcrystalline ZnFe2O4 forms from physical mixtures after prolonged annealing at 1000 °C while nanocrystalline ZnFe2O4 powders are produced by mild annealing (1 h at 500 °C in air) of mechanically activated mixtures. The magnetic properties of ZnFe2O4 powders obtained from physical and from milled mixtures are compared. 相似文献
22.
Berbenni V. Marini A. Bruni G. Maggioni A. Cogliati P. 《Journal of Thermal Analysis and Calorimetry》2002,68(2):413-422
A physico-chemical characterization of dipyridamole (C24H40N8O4), a widely used anti-aggregating agent, has been performed by using a combination of thermoanalytical (DSC) and spectroscopic
(XRPD and FT-IR/PAS) techniques. A solid state transition, already reported in literature, has been ascribed to the breaking
of an intramolecular H-bonds network. The rupture of a network of intermolecular H-bonds is thought to accompany the fusion.
The solid state transition has been shown to be reversible provided the sample has not undergone melting.
Mechanical milling and thermal annealing have been shown to decrease melting temperature and enthalpy. The effect brought
about by mechanical and thermal treatment on the solid state transition is different. In the milled samples the transition
peak shifts towards lower temperatures and its enthalpy suggests that all intramolecular H-bonds have been transformed into
intermolecular H-bonds.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
23.
Marini A. Berbenni V. Pegoretti M. Bruni G. Cofrancesco P. Sinistri C. Villa M. 《Journal of Thermal Analysis and Calorimetry》2003,73(2):547-561
We apply a range of techniques (thermal methods, microscopy, X-ray diffraction, IR spectroscopy) to characterize a drug (atenolol), several excipients (PVP=polyvinylpyrrolidone, MGST=magnesium stearate, Avicel©) and drug-excipients mixtures either as prepared, annealed, and exposed to moisture. We compare the data of the mixtures with those computed from a weighted average of similarly treated pure compounds to find evidence of drug properties modified by the interaction with the excipient. We find that thermal response is by far the most sensitive indicator of interaction while IR is the least sensitive one. Avicel© has essentially no interaction with atenolol, while MGST modifies significantly only the thermal response of the drug in the MGST-rich mixtures. PVP interacts strongly with atenolol, and this interaction appears to be mediated by the substantial amount of hydration water the excipient brings in its mixtures with a water-free drug. 相似文献
24.
Giovanna Bruni Vittorio Berbenni Chiara Milanese Alessandro Girella Amedeo Marini 《Journal of Thermal Analysis and Calorimetry》2010,102(1):193-201
This work is part of a systematic study undertaken to find and optimize a general method of detecting the drug-excipient interactions,
with the aim of predicting rapidly and inexpensively the long term stability of a pharmaceutical product and speed up its
marketing. Here, in particular, the compatibility of haloperidol with several excipients (PVP, magnesium stearate and α-lactose)
in binary and ternary mixtures, both as prepared and ball-milled, has been assessed by thermal methods, electron microscopy,
IR spectroscopy and X-ray diffraction. The differences between the experimental behaviour of the systems and that expected
as weighted average of similarly treated pure components are interaction indicators. The DSC has proven to be, among the selected
analytical techniques, the most sensitive and specific in assessing the compatibility. A strong interaction has been observed
between PVP and haloperidol. It is favoured by the mechanical stress and is more evident in the composition 20:80. On the
contrary, α-lactose and magnesium stearate were found to be compatible with the drug. 相似文献
25.
G. Bruni V. Berbenni C. Milanese A. Girella P. Cofrancesco G. Bellazzi A. Marini 《Journal of Thermal Analysis and Calorimetry》2009,95(3):871-876
In this work the solid-state characterization of anhydrous D-mannitol has been performed: α and β modifications can be distinguished only by XRPD and FTIR as they show melting temperature
and enthalpy that are the same within the standard deviation. The understanding of the thermal behaviour of the δ form (obtained
by re-crystallization in acetone) has required XRPD experiments performed at variable temperature. This form during heating
undergoes a solid phase transition to α modification. By cooling a melted sample, under a wide range of experimental conditions,
a very fast crystallization occurs. Independently of the starting crystal form (β or δ form), the re-crystallization of D-mannitol from melt always leads to α form. 相似文献
26.
Bruni Giovanna Monteforte Francesco Maggi Lauretta Friuli Valeria Ferrara Chiara Mustarelli Piercarlo Girella Alessandro Berbenni Vittorio Capsoni Doretta Milanese Chiara Marini Amedeo 《Journal of Thermal Analysis and Calorimetry》2020,140(4):1859-1869
Journal of Thermal Analysis and Calorimetry - The eco-friendly method of kneading was here used to synthesize a cocrystal of probenecid, an uricosuric drug used in treating gout and hyperuricemia,... 相似文献
27.
Nicolas NicaiseStéphane Berbenni Francis WagnerMarcel Berveiller Xavier Lemoine 《International Journal of Plasticity》2011,27(2):232-249
Micro-macro scale transition theories were developed to model the inelastic behaviour of polycrystals starting from the local behaviour of the grains. The anisotropy of the plastic behaviour of polycrystalline metals was essentially explained by taking into account the crystallographic textures. Issues like plastic heterogeneities due to grain size dispersion, involving the Hall-Petch mechanism at the grain scale, were often not taken into account, and, only the role of a mean grain size was investigated in the literature. Here, both sources of plastic heterogeneities are studied using: (i) experimental data from EBSD measurements and tensile tests, and, (ii) a self-consistent model devoted to elastic-viscoplastic heterogeneous materials. The results of the model are applied to two different industrial IF steels with similar global orientation distributions functions but different mean grain sizes and grain size distributions. The coupled role of grain size distributions and crystallographic textures on the overall tensile behaviour, local stresses and strains, stored energy and overall plastic anisotropy (Lankford coefficients) is deeply analyzed by considering different other possible correlations between crystallographic orientations and grain sizes from the measured data. 相似文献
28.
Christophe Collard Véronique Favier Stéphane Berbenni Marcel Berveiller 《International Journal of Plasticity》2010
This work investigates a new micromechanical modeling of polycrystal plasticity, accounting slip bands for physical plastic heterogeneities considered as periodically distributed within grains. These intra-granular plastic heterogeneities are modeled by parallel flat ellipsoidal sub-domains, each of them may have a distinct uniform plastic slip. To capture the morphology of slip bands occurring in plastically deforming polycrystals, these interacting sub-domains are considered as oblate spheroids periodically distributed and constrained by spherical grain boundaries. In this paper, we focus the study on the influences of internal length scale parameters related to grain size, spatial period and thickness of slip bands on the overall material’s behavior. In a first part, the Gibbs free energy accounting for elastic interactions between plastic heterogeneities is calculated thanks to the Green function’s method in the case of an isolated spherical grain with plastic strain occurring only in slip bands embedded in an infinite elastic matrix. In a second part, the influence of discrete periodic distributions of intra-granular slip bands on the polycrystal’s behavior is investigated considering an aggregate with random crystallographic orientations. When the spatial period of slip bands is on the same order as the grain radius, the polycrystal’s mechanical behavior is found strongly dependent on the ratio between the spatial period of slip bands and the grain size, as well as the ratio between the slip band thickness and the grain size, which cannot be captured by classic length scale independent Eshelby-based micromechanics. 相似文献
29.
Bruni Giovanna Sakaj Mirena Berbenni Vittorio Maggi Lauretta Friuli Valeria Girella Alessandro Milanese Chiara Marini Amedeo 《Journal of Thermal Analysis and Calorimetry》2019,136(5):2063-2070
Journal of Thermal Analysis and Calorimetry - Sulindac is a nonsteroidal anti-inflammatory drug with poor water solubility. This study presents a way to increase its dissolution rate while reducing... 相似文献
30.