1,510 research outputs found

    Algebraic-matrix calculation of vibrational levels of triatomic molecules

    Full text link
    We introduce an accurate and efficient algebraic technique for the computation of the vibrational spectra of triatomic molecules, of both linear and bent equilibrium geometry. The full three-dimensional potential energy surface (PES), which can be based on entirely {\it ab initio} data, is parameterized as a product Morse-cosine expansion, expressed in bond-angle internal coordinates, and includes explicit interactions among the local modes. We describe the stretching degrees of freedom in the framework of a Morse-type expansion on a suitable algebraic basis, which provides exact analytical expressions for the elements of a sparse Hamiltonian matrix. Likewise, we use a cosine power expansion on a spherical harmonics basis for the bending degree of freedom. The resulting matrix representation in the product space is very sparse and vibrational levels and eigenfunctions can be obtained by efficient diagonalization techniques. We apply this method to carbonyl sulfide OCS, hydrogen cyanide HCN, water H2_2O, and nitrogen dioxide NO2_2. When we base our calculations on high-quality PESs tuned to the experimental data, the computed spectra are in very good agreement with the observed band origins.Comment: 11 pages, 2 figures, containg additional supporting information in epaps.ps (results in tables, which are useful but not too important for the paper

    Detailed site distribution of melanoma and sunlight exposure: aetiological patterns from a Swiss series

    Get PDF
    Background: The relation between detailed cutaneous distribution of melanoma and indicators of sun exposure patterns has scantily been explored in moderately sun-sensitive populations. Patients and methods: The precise site of 1658 primary malignant melanoma, registered from 1995 to 2002, in Switzerland were retrieved and clinically validated. Relative melanoma density (RMD) was computed by the ratio of observed to expected number of melanoma allowing for body site surface areas, and further adjusted for site-specific melanocyte density. Results: Sites of highest risks were the face, shoulder and upper arm for both sexes, the back for men, and leg for women. Major features of this series were: (i) an unexpectedly high RMD for the face in women (5.6 versus 3.7 in men), (ii) the absence of a male predominance for melanoma on the ears and (iii) for the upper limbs, a steady gradient of increasing melanoma density with increasing proximity to the trunk, regardless of sex. Age and sex patterns of RMD parallelled general indicators of sun exposure and behaviour, except for the hand (RMD = 0.2). Conclusion: RMD increased with (cumulative) site sun exposure, but a few notable exceptions support the impact of intermittent exposure in melanoma ris

    Improving spatial landslide prediction with 3d slope stability analysis and genetic algorithm optimization: Application to the oltrepò pavese

    Get PDF
    In this study, we compare infinite slope and the three-dimensional stability analysis performed by SCOOPS 3D (software to analyze three-dimensional slope stability throughout a digital landscape). SCOOPS 3D is a model proposed by the U. S. Geological Survey (USGS), the potentialities of which have still not been investigated sufficiently. The comparison between infinite slope and 3D slope stability analysis is carried out using the same hydrological analysis, which is performed with TRIGRS (transient rainfall infiltration and grid-based regional slope-stability model)—another model proposed by USGS. The SCOOPS 3D model requires definition of a series of numerical parameters that can have a significant impact on its own performance, for a given set of physical properties. In the study, we calibrate these numerical parameters through a multi-objective optimization based on genetic algorithms to maximize the model predictability performance in terms of statistics of the receiver operating characteristics (ROC) confusion matrix. This comparison is carried out through an application on a real case study, a catchment in the Oltrepò Pavese (Italy), in which the areas of triggered landslides were accurately monitored during an extreme rainfall on 27–28 April 2009. Results show that the SCOOPS 3D model performs better than the 1D infinite slope stability analysis, as the ROC True Skill Statistic increases from 0.09 to 0.37. In comparison to other studies, we find the 1D model performs worse, likely for the availability of less detailed geological data. On the other side, for the 3D model we find even better results than the two other studies present to date in the scientific literature. This is to be attributed to the optimization process we proposed, which allows to have a greater gain of performance passing from the 1D to the 3D simulation, in comparison to the above-mentioned studies, where no optimization has been applied. Thus, our study contributes to improving the performances of landslide models, which still remain subject to many uncertainty factors

    (Poly)phenolic content and profile and antioxidant capacity of whole-grain cookies are better estimated by simulated digestion than chemical extraction

    Get PDF
    It is widely recognized that the biological effects of phytochemicals cannot be attributed to the native compounds present in foods but rather to their metabolites endogenously released after intake. Bioavailability depends on bioaccessibility, which is the amount of the food constituent that is released from the matrix in the gastrointestinal tract. The use of chemical extraction to evaluate the content and profile of phytochemicals does not mirror the physiological situation in vivo, and their bioaccessibility should be considered while assessing their nutritional significance in human health. The current study was designed to compare the (poly)phenolic profile and content and antioxidant capacity of whole-grain (WG) cookies using chemical extraction and a more physiological approach based on simulated digestion. Three types of organic WG cookies (made with durum, Italian khorasan, or KAMUT\uae khorasan wheat) were considered, either fermented by Saccharomyces Cerevisiae or sourdough. Although the flour type and the fermentation process influenced the release of phytochemicals from the cookie matrix, in almost all samples, the simulated digestion appeared the most efficient procedure. Our results indicate that the use of chemical extraction for evaluation of the phytochemicals content and antioxidant capacity of food could lead to underestimation and underline the need for more physiological extraction methods

    Malonic acid: A potential reagent in decontamination processes for Ni-rich alloy surfaces

    Get PDF
    The ability of malonic acid as a dissolution agent toward synthetic Ni ferrite and Alloy 600 and 800 corrosion products was explored. Its performance in the dissolution kinetics of Ni ferrite powders was compared with the one of oxalic acid. Kinetic parameters were obtained and the dependency on external Fe(II) was modelled. Oxidized samples used in descaling tests were prepared by exposure of coupons of both alloys to lithiated aqueous solutions, under hydrothermal conditions and hydrogen overpressure, simulating PHWR conditions. Oxide layer morphology, the influence of exposure time to corrosive medium and LiOH concentration on its thickness were characterized. Descaling tests consisting on a two-stage method (a first oxidizing step with alkaline permanganate followed by a reducing step with oxalic or malonic acid were carried out). Results were compared to those obtained with a well known chemical cleaning formulation (APAC: Alkaline Permanganate Ammonium Citrate) used in decontamination of several reactors and loops and the competitiveness of malonic acid was demonstrated.Fil: García, D.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Instituto Sabato; ArgentinaFil: Bruyre, V. I. E.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Instituto Sabato; ArgentinaFil: Bordoni, R.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Olmedo, A. M.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Morando, Pedro Juan. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Instituto Sabato; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Design, synthesis and anthelmintic activity of 7-keto-sempervirol analogues

    Get PDF
    The plant-derived, diterpenoid 7-keto-sempervirol was recently reported to display moderate activity against larval stages of Schistosoma mansoni (IC50 = 19.1 μM) and Fasciola hepatica (IC50 = 17.7 μM), two related parasitic blood and liver flukes responsible for the neglected tropical diseases schistosomiasis and fascioliasis, respectively. Here, we aimed to increase the potency of 7-keto-sempervirol by total synthesis of 30 structural analogues. Subsequent screening of these new diterpenoids against juvenile and adult lifecycle stages of both parasites as well as the human HepG2 liver cell line and the bovine MDBK kidney cell line revealed structure-activity relationship trends. The most active analogue, 7d, displayed improved dual anthelmintic activity over 7-keto-sempervirol (IC50 ≈ 6 μM for larval blood flukes; IC50 ≈ 3 μM for juvenile liver flukes) and moderate selectivity (SI ≈ 4–5 for blood flukes, 8–13 for liver flukes compared to HepG2 and MDBK cells, respectively). Phenotypic studies using scanning electron microscopy revealed substantial tegumental alterations in both helminth species, supporting the hypothesis that the parasite surface is one of the main targets of this family of molecules. Further modifications of 7d could lead to greater potency and selectivity metrics resulting in a new class of broad-spectrum anthelmintic

    A microseismic study in a low seismicityarea: the 2001 site-response experimentin the Città di Castello Basin (Italy)

    Get PDF
    A site response experiment was performed in the basin of Città di Castello (a small town in Central Italy) in May 2001. This study is part of a project on the evaluation of seismic hazard in seismogenic areas funded by the Gruppo Nazionale Difesa dai Terremoti (GNDT). The experiment consisted of a dense fixed transect configuration with most of the stations recording in continuous mode, and several ambient noise measurements both in single station and in array configuration spread over the investigated area. The dense transect was composed of 26 seismic stations in a crosswise configuration with a maximum inter-station distance of 250 m. The stations were deployed in the southern part of the basin, from the eastern bedrock outcrop to the western edge, across the town. About 70 earthquakes were recorded during 10 days of deployment, generally low magnitude or regional events. We located 23 earthquakes and 17 of them were located using the waveform similarity approach at 4 stations outside the target area. These 4 stations were part of a dense temporary seismic network involved in a previous experiment of the same project, aimed at performing a high-resolution picture of the local seismicity. Delay analysis on the recorded waveforms allowed us to infer the basin geometry at depth and estimate the S-wave velocity of sediments. Moreover, we evaluated relative site response along the E-W transect by performing a standard spectral ratio. Amplification factors up to 9 are found inside the basin; at frequencies above 5 Hz stations closer to the edges show higher amplification, whereas stations located in the middle of the basin, where the alluvial sediments are thicker (CD11-CD14), show higher amplification below 5 Hz. We considered the average amplification in two frequency bands (1-5 Hz and 5-10 Hz), representative of the resonance frequency for 2-3 storey buildings and 1 storey houses,respectively. Our results suggest that the potential hazard for 2-3 storey buildings is higher in the center of the basin (amplification factor up to 6), and for 1 storey houses is higher at the edges (amplification factor up to 5)

    Synthesis of novel structural hybrids between aza-heterocycles and azelaic acid moiety with a specific activity on osteosarcoma cells

    Get PDF
    Nine compounds bearing pyridinyl (or piperidinyl, benzimidazolyl, benzotriazolyl) groups bound to an azelayl moiety through an amide bond were synthesized. The structural analogy with some histone deacetylase inhibitors inspired their syntheses, seeking new selective histone deacetylase inhibitors (HDACi). The azelayl moiety recalls part of 9-hydroxystearic acid, a cellular lipid showing antiproliferative activity toward cancer cells with HDAC as a molecular target. Azelayl derivatives bound to a benzothiazolyl moiety further proved to be active as HDACi. The novel compounds were tested on a panel of both normal and tumor cell lines. Non-specific induction of cytotoxicity was observed in the normal cell line, while three of them induced a biological effect only on the osteosarcoma (U2OS) cell line. One of them induced a change in nuclear shape and size. Cell-cycle alterations are associated with post-transcriptional modification of both H2/H3 and H4 histones. In line with recent studies, revealing unexpected HDAC7 function in osteoclasts, molecular docking studies on the active molecules predicted their proneness to interact with HDAC7. By reducing side effects associated with the action of the first-generation inhibitors, the herein reported compounds, thus, sound promising as selective HDACi

    Effetti di sito della piana del Fucino attraverso lo studio comparato di dati sismici e geologici

    Get PDF
    Il presente lavoro è incentrato nello studio della Piana del Fucino in termini di risposta sismica attraverso metodi di analisi geofisica e correlazioni dei risultati ottenuti con la geologia dell’area. Uno dei terremoti più disastrosi della storia italiana è quello verificatosi nel gennaio del 1915 nella Marsica; ciò testimonia che l’area oggetto di studio è fortemente esposta al rischio sismico. È quindi opportuno provvedere alla riduzione di tale rischio operando in termini di prevenzione. Uno dei metodi consiste nella determinazione dei livelli di scuotimento al suolo attesi in caso di terremoto attraverso lo studio degli effetti di sito. Per fare ciò si sono utilizzati i segnali sismici registrati da una rete di stazioni installate dall’Istituto Nazionale di Geofisica e Vulcanologia per la caratterizzazione geologico-geotecnica dei siti delle stazioni accelerometriche della Rete Accelerometrica Nazionale (richiesto in uno dei Progetti previsti della convenzione tra il Dipartimento della Protezione Civile e l’INGV nel triennio 2007- 2009). L’intervallo temporale coperto dalle stazioni va dall’ottobre 2008 al settembre 2009 ed il dataset selezionato comprende terremoti con Magnitudo superiore a 2 entro un raggio medio di 60 km da Avezzano. In seconda istanza si è proceduto all’installazione di altre stazioni temporanee sempre all’interno della Piana con lo scopo di registrare rumore ambientale a completamento dei dati già in possesso
    • …
    corecore