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81.
Elia Monsivais-Gámez Facundo Ruiz J. R. Martínez 《Journal of Sol-Gel Science and Technology》2007,43(1):65-72
We calculate the vibrational modes of four-membered rings family in the Si–O extended rocking infrared for vitreous SiO2 materials. In particular these species are obtained in the early stages of the sol–gel process. We have performed high quality
quantum-mechanical calculations based on cluster models and gradient corrected density functional theory, (GC-DFT). Three
possible configurations were obtained, a regular planar, a slightly deformed or quasi-planar, and a deformed ring. According
to our result, the more probable one is the slightly deformed configuration. The calculated vibrational frequencies are compared
with experimental IR and Raman results obtaining very good agreement. Also, we calculated geometries and vibrational frecuencies
for three-membered rings. We found that 3- and 4-fold rings show evidence of decoupled vibrational modes, those modes are
compared with a Raman spectrum obtaining very good coincidence. 相似文献
82.
Guido Barone Giuseppina Castronuovo Attilio Cesáro Vittorio Elia 《Journal of solution chemistry》1980,9(11):867-876
The heats of mixing of the aqueous solutions of monomethylurea, monoethylurea, 1,3-dimethylurea, 1,3-diethylurea were determined at 25°C. The excess enthalpies obtained are expressed in virial form, in terms of pair and triplet interaction coefficients. A method previously discussed for predicting the excess enthalpies and the interaction coefficients of ternary solutions has been applied to the alkylureas. The large deviations between the experimental and calculated values, led to the modification of that method, which better accounts for the marked mixed character of these substances. 相似文献
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86.
Francesco Boschetto Hoan Ngoc Doan Phu Phong Vo Matteo Zanocco Kenta Yamamoto Wenliang Zhu Tetsuya Adachi Kenji Kinashi Elia Marin Giuseppe Pezzotti 《Molecules (Basel, Switzerland)》2021,26(10)
The present work investigated the effect of Polylactic acid (PLA) fibers produced by centrifugal spinning with incorporated BaTiO3 particles to improve their bacteriostatic behavior. The PLA matrix and three composites, presenting three different amounts of fillers, were subjected to UV/O3 treatment monitoring the possible modifications that occurred over time. The morphological and physical properties of the surfaces were characterized by different microscopic techniques, contact angle, and surface potential measurements. Subsequently, the samples were tested in vitro with human dermal fibroblasts (HDF) to verify the cytotoxicity of the substrates. No significant differences between the PLA matrix and composites emerged; the high hydrophobicity of the fibers, derived by the polymer structure, represented an obstacle limiting the fibroblast attachment. Samples underwent bacterial exposure (Staphylococcus epidermidis) for 12 and 24 h. Increasing the concentration of BT, the number of living bacteria and their distribution decreased in comparison with the PLA matrix suggesting an effect of the inorganic filler, which generates a neutralization effect leading to reactive oxygen species (ROS) generation and subsequently to bacterial damages. These results suggest that the barium titanate (BT) fillers clearly improve the antibacterial properties of PLA fibers after aging tests made before bacterial exposure, representing a potential candidate in the creation of composites for medical applications. 相似文献
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In this paper we propose and implement numerical methods to detect exponential dichotomy on the real line. Our algorithms
are based on the singular value decomposition and the QR factorization of a fundamental matrix solution. The theoretical justification
for our methods was laid down in the companion paper: “Exponential Dichotomy on the real line: SVD and QR methods.” 相似文献
89.
Szekeres E Acosta E Sabatini DA Harwell JH 《Journal of colloid and interface science》2006,294(1):222-233
Polar/amphiphilic oils, called lipophilic linkers, are sometimes added to oil-water-ionic surfactant microemulsions in order to increase the solubilization of hydrophobic oils. The solubilization increase has been well documented for a number of systems. However, mathematical models to calculate the solubilization increase have been proposed only for optimum microemulsions (i.e., middle phase microemulsions solubilizing equal volumes of oil and water). In this paper we propose a model, which predicts solubilization enhancement for non-optimum microemulsion systems as well. The model is an extension of the net-average curvature model of microemulsion. The net-average curvature model is combined with a surface activity model to account for the increased palisade layer solubilization due to the presence of the polar/amphiphilic oil component. New non-linear mixing rules are also incorporated to account for the optimum salinity and the characteristic length variation of the anionic surfactant microemulsion as a function of the lipophilic linker concentration. The model predicts the effect of the lipophilic linker and the electrolyte concentration on the oil solubilization in accordance with the experimental results. 相似文献
90.
Elia A Rizzi F Di Franco C Lugarà PM Scamarcio G 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(2):426-429
The use of photoacoustic spectroscopy and mid-infrared quantum-cascade lasers (QCLs) for the detection of hexamethyldisilazane (HMDS) is reported. A detection limit of 200 parts in 10(9) is found using a Fabry-Perot QCL operated at 8.4 microm in pulsed mode and a photoacoustic cell equipped with four electret microphones. The laser multimode spectrum matches the range of the N-H bending absorption band of HMDS. Further improvements to reach lower detection limits are discussed. 相似文献