3,240 research outputs found

    MOCVD-Fabricated TiO2 Thin Films: Influence of Growth Conditions on Fibroblast Cells Culture

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    TiO2 thin films with various morphologies were grown on Ti substrates by the LP-MOCVD technique (Low Pressure Chemical Vapour Deposition from Metal-Organic precursor), with titanium tetra-iso-propoxide as a precursor. All the films were prepared in the same conditions except the deposition time. They were characterized by X-ray diffraction, scanning electron microscopy, optical 15 interferometry, water contact angle measurements. MOCVD-fabricated TiO2 thin films are known to be adapted to cell culture for implant requirements. Human gingival fibroblasts were cultured on the various TiO2 deposits. Differences in cell viability (MTT tests) and cell spreading (qualitative assessment) were observed and related to film roughness, wettability and allotropic composition

    Iris Codes Classification Using Discriminant and Witness Directions

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    The main topic discussed in this paper is how to use intelligence for biometric decision defuzzification. A neural training model is proposed and tested here as a possible solution for dealing with natural fuzzification that appears between the intra- and inter-class distribution of scores computed during iris recognition tests. It is shown here that the use of proposed neural network support leads to an improvement in the artificial perception of the separation between the intra- and inter-class score distributions by moving them away from each other.Comment: 6 pages, 5 figures, Proc. 5th IEEE Int. Symp. on Computational Intelligence and Intelligent Informatics (Floriana, Malta, September 15-17), ISBN: 978-1-4577-1861-8 (electronic), 978-1-4577-1860-1 (print

    Dioxygen Reactivity of Biomimetic Fe(II) Complexes with Noninnocent Catecholate, \u3cem\u3eo\u3c/em\u3e-Aminophenolate, and \u3cem\u3eo\u3c/em\u3e-Phenylenediamine Ligands

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    This study describes the O2 reactivity of a series of high-spin mononuclear Fe(II) complexes each containing the facially coordinating tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (Ph2TIP) ligand and one of the following bidentate, redox-active ligands: 4-tert-butylcatecholate (tBuCatH–), 4,6-di-tert-butyl-2-aminophenolate (tBu2APH–), or 4-tert-butyl-1,2-phenylenediamine (tBuPDA). The preparation and X-ray structural characterization of [Fe2+(Ph2TIP)(tBuCatH)]OTf, [3]OTf and [Fe2+(Ph2TIP)(tBuPDA)](OTf)2, [4](OTf)2 are described here, whereas [Fe2+(Ph2TIP)(tBu2APH)]OTf, [2]OTf was reported in our previous paper [Bittner et al., Chem.—Eur. J. 2013, 19, 9686–9698]. These complexes mimic the substrate-bound active sites of nonheme iron dioxygenases, which catalyze the oxidative ring-cleavage of aromatic substrates like catechols and aminophenols. Each complex is oxidized in the presence of O2, and the geometric and electronic structures of the resulting complexes were examined with spectroscopic (absorption, EPR, Mössbauer, resonance Raman) and density functional theory (DFT) methods. Complex [3]OTf reacts rapidly with O2 to yield the ferric-catecholate species [Fe3+(Ph2TIP)(tBuCat)]+ (3ox), which undergoes further oxidation to generate an extradiol cleavage product. In contrast, complex [4]2+ experiences a two-electron (2e–), ligand-based oxidation to give [Fe2+(Ph2TIP)(tBuDIBQ)]2+ (4ox), where DIBQ is o-diiminobenzoquinone. The reaction of [2]+ with O2 is also a 2e– process, yet in this case both the Fe center and tBu2AP ligand are oxidized; the resulting complex (2ox) is best described as [Fe3+(Ph2TIP)(tBu2ISQ)]+, where ISQ is o-iminobenzosemiquinone. Thus, the oxidized complexes display a remarkable continuum of electronic structures ranging from [Fe3+(L2–)]+ (3ox) to [Fe3+(L‱–)]2+ (2ox) to [Fe2+(L0)]2+ (4ox). Notably, the O2 reaction rates vary by a factor of 105 across the series, following the order [3]+ \u3e [2]+ \u3e [4]2+, even though the complexes have similar structures and Fe3+/2+ redox potentials. To account for the kinetic data, we examined the relative abilities of the title complexes to bind O2 and participate in H-atom transfer reactions. We conclude that the trend in O2 reactivity can be rationalized by accounting for the role of proton transfer(s) in the overall reaction

    Synthetic, Spectroscopic and DFT Studies of Iron Complexes with Iminobenzo(semi)quinone Ligands: Implications for o-Aminophenol Dioxygenases

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    The oxidative CC bond cleavage of o-aminophenols by nonheme Fe dioxygenases is a critical step in both human metabolism (the kynurenine pathway) and the microbial degradation of nitroaromatic pollutants. The catalytic cycle of o-aminophenol dioxygenases (APDOs) has been proposed to involve formation of an FeII/O2/iminobenzosemiquinone complex, although the presence of a substrate radical has been called into question by studies of related ring-cleaving dioxygenases. Recently, we reported the first synthesis of an iron(II) complex coordinated to an iminobenzosemiquinone (ISQ) ligand, namely, [Fe(Tp)(tBuISQ)] (2 a; where Tp=hydrotris(3,5-diphenylpyrazol-1-yl)borate and tBuISQ is the radical anion derived from 2-amino-4,6-di-tert-butylphenol). In the current manuscript, density functional theory (DFT) calculations and a wide variety of spectroscopic methods (electronic absorption, Mössbauer, magnetic circular dichroism, and resonance Raman) were employed to obtain detailed electronic-structure descriptions of 2 a and its one-electron oxidized derivative [3 a]+. In addition, we describe the synthesis and characterization of a parallel series of complexes featuring the neutral supporting ligand tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (TIP). The isomer shifts of about 0.97 mm s−1 obtained through Mössbauer experiments confirm that 2 a (and its TIP-based analogue [2 b]+) contain FeII centers, and the presence of an ISQ radical was verified by analysis of the absorption spectra in light of time-dependent DFT calculations. The collective spectroscopic data indicate that one-electron oxidation of the FeII–ISQ complexes yields complexes ([3 a]+ and [3 b]2+) with electronic configurations between the FeIII–ISQ and FeII–IBQ limits (IBQ=iminobenzoquinone), highlighting the ability of o-amidophenolates to access multiple oxidation states. The implications of these results for the mechanism of APDOs and other ring-cleaving dioxygenases are discussed

    On the volume of the set of mixed entangled states

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    A natural measure in the space of density matrices describing N-dimensional quantum systems is proposed. We study the probability P that a quantum state chosen randomly with respect to the natural measure is not entangled (is separable). We find analytical lower and upper bounds for this quantity. Numerical calculations give P = 0.632 for N=4 and P=0.384 for N=6, and indicate that P decreases exponentially with N. Analysis of a conditional measure of separability under the condition of fixed purity shows a clear dualism between purity and separability: entanglement is typical for pure states, while separability is connected with quantum mixtures. In particular, states of sufficiently low purity are necessarily separable.Comment: 10 pages in LaTex - RevTex + 4 figures in eps. submitted to Phys. Rev.

    IoT Architecture for a sustainable tourism application in a smart city environment

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    In the past few years, the Smart Cities concept has become one of the main driving forces for the urban transition towards a low carbon environment, sustainable economy, andmobility. Tourism, as one of the fastest growing industries, is also an important generator of carbon emissions; therefore, the recently emerging sustainable tourism concept is envisioned as an important part of the Smart Cities paradigm.Within this context, the Internet-of-Things (IoT) concept is the key technological point for the development of smart urban environments through the use of aggregated data, integrated in a single decisional platform. This paper performs the first analysis on the feasibility of the use of an IoT approach and proposes a specific architecture for a sustainable tourism application. The architecture is tailored for the optimisation of the movement of cruise ship tourists in the city of Cagliari (Italy), by taking into consideration factors such as transport information and queue waiting times. A first set of simulations is performed using 67-point of interest, real transportation data, and an optimisation algorithm

    Endothelial progenitor cells populate the stromal stem niche of tympanum

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    The tympanic membrane (TM) integrity is of utmost importance for the sense of hearing. Therefore, the intrinsic potential of the TM to regenerate and repair deserves complete characterisation. Existing studies brought evidence on the epithelial stem niche of the TM. However, the stromal compartment was not evaluated for harbouring a distinctive stem, or progenitor, niche. We aimed doing this in transmission electron microscopy. We used TMs dissected out from 3 male Oryctolagus cuniculus rabbits. Evidence of stromal quiescent stem cells was gathered. Moreover, endothelial progenitor cells were found in the TM, being accurately identified by two specific ultrastructural markers of the endothelial lineage: the Weibel-Palade bodies and the stomatal diaphragms of the subplasmalemmal caveolae. The stromal stem niche of the TM appears to be a distinctive contributor during physiological and pathological processes of the TM, such as cholesteatoma formation, at least as a biological support for processes of vasculogenesis. However, further characterisation of the molecular pattern of the stromal stem niche of the TM is mandatory
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