1,721,835 research outputs found
Numerical investigation on mixed convection in triangular cross section ducts with nanofluids
No full text"\"Convective heat transfer can be enhanced passively by changing flow geometry and boundary conditions or by improving the thermal conductivity of the working fluid, for example, introducing suspended small solid nanoparticles. In this paper, a numerical investigation on laminar mixed convection in a water-Al2O3-based nanofluid, flowing in a triangular cross-sectioned duct, is presented. The duct walls are assumed at uniform temperature, and the single-phase model has been employed in order to analyze the nanofluid behaviour. The hydraulic diameter is equal to 0.01 m. A fluid flow with different values of Richardson number and nanoparticle volume fractions has been considered. Results show the increase of average convective heat transfer coefficient and Nusselt number for increasing values of Richardson number and particle concentration. However, also wall shear stress and required pumping power profiles grow significantly.\"
Scanning force microscopy on live cultured cells: Imaging and force‐versus‐distance investigations
No full textExtensive measurements with the scanning force microscope on living cells in their native liquid environment are described with the purpose of critically assessing the extent of the interaction between the SFM tip and the (soft) cell materials and the effect of such interaction on topographic information. Images are obtained under various force conditions and systematically correlated with force‐versus‐distance curves. As a result, detailed indications about tip indentation are given, thickness estimates deduced and identification of submembranous cytoplasmic structures suggested. 1994 Blackwell Science Lt
Chemical composition and antifungal activity of the essential oil of Cotinus coggygria Scoop. from marche region (Italy)
No full textThe present study reports the results of gas chromatography-mass spectrometry (GC/MS) analyses of the essential oil from flowering aerial parts of Cotinus coggygria Scoop. (Anacardiaceae), as well as its in vitro antifungal activity against nine plant pathogenic fungi. Moreover, the essential oil was evaluated for its antifungal activity using the agar dilution method, and also MICs (minimum inhibitory concentrations) and MFCs (minimum fungicidal concentrations) were determined. The major compounds identified by GC-MS were limonene (49.2%), (Z)-β-ocimene (13.6%), α-pinene (8.8%) and (E)-β-ocimene (5.9%). The oil showed in vitro antifungal activity against some species of the Fusarium genus, Botrytis cinerea, and Alternaria solani. Our study indicates that the oil of C. coggygria could be used as a control agent for plant pathogenic fungi in natural formulations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
La FAO e l’approccio partecipativo alla sicurezza alimentare: il caso della delimitazione della terra nella comunità di Kacua
No full textMulti-walled carbon nanotubes plastic actuator
No full textCarbon nanotubes (CNTs) have electrical and mechanical properties that make them highly attractive for actuators. They have the ability to deform elastically by several percent, thus storing very large amounts of energy, thanks to their crystalline nature and to their morphology. A bimorph actuator composed of single-walled carbon nanotubes (SWCNTs), polyvinylidene difluoride (PVdF) and the ionic liquid (IL) 1-butyl 3-methylimidazolium tetrafluoroborate [BMIM][BF4] with a polymer-supported internal IL electrolyte was previously demonstrated by Aida and coworkers. While several experiments were carried out using SWCNTs, PVdF and a number of ILs, the use of multi-walled carbon nanotubes (MWCNTs) instead of SWCNTs is, to our knowledge, a new result that will be presented here. Electrochemical characterizations by cyclic voltammetry (CV), and actuation tests performed applying a square wave of 4 V peak-to-peak at frequencies between 0.3 and 2 Hz are reported and discussed. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Natural products from higher plants and marine organisms as sources of new anticancer agents: synthesis and biological evaluation
Full text linkAbstract part A: The dysregulation of the Hedgehog (Hh) signaling pathway plays a pivotal role in the generation and cell-manteinance of many human cancers. Gli transcription factors, the final effectors of the pathway, represent the most promising target for the development of new drugs targeting the Hh pathway in tumors. In a previous work, a natural isoflavone, glabrescione B (GlaB) (I), was identified as the first small molecule binding Gli1. It is able to inhibit the transcriptional activity of Gli1, by interfering with its interaction with DNA. In order to perform further studies on the mechanism of action of GlaB (I) we developed a total synthesis, while NMR studies demonstrated the interaction of GlaB with Gli1
Biological studies have demonstrated its ability to interfere with the activity of Gli1 by inhibiting the growth of Gli-dependent-Hh-dependent tumor cells such as medulloblastoma (MB) and basal cell carcinoma (BCC) both in vitro and in allograft mouse models.
In addition, our new synthetic route, which encompasses just three steps with an overall yield of 15%, provided an efficient synthetic means to enable the investigation of the role of GlaB ring-B in the interaction Gli1-GlaB. In fact, our synthetic strategy allowed the preparation of several GlaB derivativesin order to elucidate the structure-activity relationships (SARs) and to clarify the molecular mechanism underlying its Hedgehog signalling modulation.Abstract part B: The second part of this PhD thesis describes the work I have carried out during my research stay abroad at Swiss Federal Institute of Technology (ETH) in Zürich (Switzerland) in Prof. Dr. Karl-Heinz Altmann's laboratory. Marine natural products show higher incidence of bioactivity compared to terrestrial natural products. This is due to a high degree of chemical novelty and their high dilution in ocean water. (+)-Dactylolide (I) was isolated by Riccio and co-workers from a sponge of the genus Dactylospongia, collected off the coast of Vanuatu islands, in the South Pacific Ocean. The absolute and the relative configuration at C19 of the compound remained unassigned. The assignment of the relative and absolute configuration of (+)-dactylolide (I) is based on its first total synthesis by Smith and co-workers. As had been described for the natural product, synthetic dactylolide has been found to be dextrorotatory, but the magnitude of the specific rotation reported for the natural product and synthetic I were significantly different from each other. In addition, the discrepancies between the 13C-NMR spectra of synthetic and natural (+)-dactylolide (if ever so slight), also leave open the possibility that the configuration of C19 in natural (+)-dactylolide is R and not S (i. e. natural dactylolide could have the structure II instead of I). In order to demonstrate that, a total synthesis of both compounds was established.
(+)-Dactylolide (I) is related to (-)-zampanolide (III), another marine macrolide. The latter shows low nanomolar cytotoxicity against both drug-sensitive and multi-drug resistant cancer cell lines, and induces microtubule bundle formation. While (-)-zampanolide (III) is a nM inhibitor of cancer cell growth in vitro, not many data about the activity of (+)-dactylolide (I) have been published. On the other hand, the biological activity of synthetic (-)-dactylolide (ent-I) is well known. This compound exhibits sub-μM IC50 values against a multitude of cancer cell lines, although (–)-zampanolide (III) is still 100- to 300-fold more potent. At the same time, not even synthetic (+)-zampanolide (ent-III) has ever been tested and the importance of the configuration of the macrocycle for the potency of dextrorotatory compounds remains unclear. Our goal was to synthesize (+)-dactylolide (I) and (+)-zampanolide (ent-III), in order to investigate how the macrocycle configuration would affect the biological activity of the compounds
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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