547 research outputs found
Rational maps and string topology
No full textWe apply a version of the Chas-Sullivan-Cohen-Jones product on the higher loop homology of a manifold in order to compute the homology of the spaces of continuous and holomorphic maps of the Riemann sphere into a complex projective space. This product makes sense on the homology of maps from a co-H space to a manifold, and comes from a ring spectrum. We also build a holomorphic version of the product for maps of the Riemann sphere into homogeneous spaces. In the continuous case we define a related module structure on the homology of maps from a mapping cone into a manifold, and then describe a spectral sequence that can compute it. As a consequence we deduce a periodicity and dichotomy theorem when the source is a compact Riemann surface and the target is a complex projective space
A topological join construction and the Toda system on compact surfaces of arbitrary genus
No full textWe consider a Toda system of Liouville equations defined on a compact surface
which arises as a model for non-abelian Chern-Simons vortices. For the first
time the range of parameters , , is studied with a variational approach
on surfaces with arbitrary genus. We provide a general existence result by
means of a new improved Moser-Trudinger type inequality and introducing a
topological join construction in order to describe the interaction of the two
components
The space of linear maps into a Grassmann manifold
No full textWe show that the space of all holomorphic maps of degree one from the Rie-mann sphere into a Grassmann manifold is a sphere bundle over a flag manifold. Using the notions of "kernel" and "span" of a map, we completely identify the space of unparame-terized maps as well. The illustrative case of maps into the quadric Grassmann manifold is discussed in detail and the homology of the corresponding spaces is computed
The effects of TiO2 sol concentration on single- and multiple-scratch damage in electroplated Ni–B-TiO2 sol composite coating
No full textThe electrodeposited sol-enhanced Ni–B–TiO2 composite coatings were elaborated using a novel electroplating process. This coating was assessed in terms of tribological behavior and corrosion resistance. However, the adhesion strength of this coating has not been discussed so far. The aim of this study is to evaluate the adhesion behavior of this coating, considering different TiO2 sol concentration in the plating solution in order to predict its effectiveness and its sustainability when used in mineral crushing process. A progressive load scratch test and multi-pass scratch test were performed on coatings. The morphology of scratched surfaces was analyzed to identify the scratch failure mechanism. The results indicate that the addition of TiO2 sol significantly enhanced the deposit adhesion to the substrate compared to pure Ni–B coating. No spallation failure was observed on the sol-enhanced coatings after progressive load scratch test, contrary to Ni–B coating. Moreover, the multi-pass scratch test demonstrated that the improvement in adhesion strength depends strongly on the quantity of the TiO2 sol added to the plating solution. For the optimal concentration of TiO2 sol (25 ml/L), the sol-enhanced Ni–B–TiO2sol composite coating boasts the best adhesion strength. However, further increase in TiO2 sol concentration results in a deterioration of coating adhesion
Composition of the essential oils in various organs at different developmental stages of Ammi visnaga (L.) Lam. from Tunisia
No full textThe composition of the essential oils isolated by hydrodistillation from various organs at different development stages of Ammi visnaga (L.) Lam. growing in Tunisia was determined by GC/MS analysis. In particular, the oil profiles of the leaves, stems, flower buds, roots, umbels, and fruits have been examined during the whole life cycle. The oil from the flowering aerial parts was characterized by a high content of isoamyl 2-methylbutanoate. After flowering and during desiccation and fructification, the umbels and fruits expressed a high content of linalool. The oils, extracted from the roots collected in the vegetative, buds floral, and floral stages, were rich in monoterpene aldehydes, oxygenated monoterpenes, and monoterpene hydrocarbons. The highest level of non-terpene hydrocarbons was found at the flowerbud stage, represented by 61.3% of nonane. Among the monoterpenes, sabinene (12.5%) and β-pinene (8.5%) were identified in the flower buds
Production and characterization of a fusion form of hepatitis E virus tORF2 capsid protein in Escherichia coli
No full textHepatitis E virus (HEV) is a nonenveloped virus causing an emerging zoonotic disease posing a severe threat to the public health in the world, especially to pregnant women. In this study, a truncated form (aa 368–606) of the open reading frame 2 of the capsid protein (tORF2-HEV), a major structural protein of HEV, was expressed in Escherichia coli. This work characterizes for the first time, the fused Glutathione-S-Transferase-tagged tORF2 (GST-tORF2) and tORF2-HEV forms in E. coli. The fusion protein was purified by affinity chromatography with a purity higher than 90% and to yield about 27% after thrombin digestion. The purified GST-tORF2 protein was then characterized by western blot, using anti-GST antibodies, and CD spectroscopy. The GST-tORF2 and tORF2-HEV proteins were shown to be efficient to develop an ELISA test to detect anti-HEV IgG in mice sera immunized with a recombinant full length ORF2 protein. Sera showed a significant increase of the absorbance signal at 450 nm, in plate wells coated with a quantity of 0.5, 1 and 2 μg of proteins. ELISA plates coated with the purified GST-tORF2 and tORF2-HEV showed similar response when compared to the HEV ELISA where total insect cell lysate, infected with the recombinant baculovirus expressing full ORF2, was used as positive control
From digital cultural heritage to digital culture: Evolution in digital humanities
No full textThe paper focuses on the need to rethink digital and digitization process for long term digital preservation, aiming to redefine them as the new Cultural Heritage of the contemporary era. This new way to observe digital artifacts and their co-creation process is the indispensable prerequisite for the growth of an aware Digital Culture and for giving due importance to digitization and dematerialisation realized starting by an approach focused on data preservation and, to this goal, on the decisive role that the descriptive metadata play. The case study was the digitization project of the "Historical Archive of the Giuseppe Laterza & Figli Publishing House". In particular, the attention to preservation focused on structuring the schema of metadata and, above all, on descriptive writing, with regard to the choice of tags, elements and attributes, and to draft descriptive information of each digital artifact
Lipid components of olive oil from Tunisian cv. Sayali: characterization and authenticity
No full textThe analysis of the total lipid fraction from the Sayali variety of olive oil was accomplished in the present investigation. Glyceridic, unsaponifiable and flavour fractions of the oil were isolated and identified using several analytical methods. Chromatographic techniques have proven to be suitable for these determinations, especially capillary gas chromatography. Gas chromatography coupled to mass spectrometry was successfully used to identify sterols, triterpenes alcohols, 4-monomethylsterols, aliphatic alcohols and aroma compounds in our samples. Furthermore, solid phase microextraction was used to isolate volatiles from the total lipid fraction. Results from the quantitative characterization of Sayali olive oil showed that oleic acid (77.4%) and triolein (47.4%) were the dominant glyceridic components. However, the main compounds of the unsaponifiable fraction were b-sitosterol (147.5mg/100 g oil), 24-methylene cycloartenol (146.4mg/100 g oil) and hexacosanol (49.3 mg/100 g oil). Moreover, results showed that the aldehydic compounds were the major flavours present in Sayali olive oi
Comparative investigation of scratch resistance and tribological performance of Ni–B–TiO2 composite coatings prepared by conventional and novel processing methods
No full textNi?B?TiO2 composite coatings were elaborated by conventional and novel methods. While the first one was designed using TiO2 powder, the second was prepared by adding TiO2 sol in the bath solution. A comparative study between both coatings was performed in terms of microstructure, adhesion strength and wear resistance. To achieve a systematic study, various characterization tests were carried out, including Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), microhardness test, progressive load scratch test, reciprocating sliding test and multi-pass scratch test. The results showed that the TiO2 structure (crystalline or amorphous) has extensively changed the microstructure of Ni?B matrix. Furthermore, it was proven that the novel process provided superior scratch response and better wear resistance of the Ni?B deposit since it offers a compact structure. Nevertheless, the traditional method yielded to porous one, thus leading to mediocre mechanical properties of the same coating
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