1,721,079 research outputs found
Editorial to the special issue “lipidomics and neurodegenerative diseases”
Full text linkThe contribution of dysregulation of lipid signaling and metabolism to neurodegenerative diseases including Alzheimer’s and Parkinson’s is the focus of this special issue. Here, the matter of three reviews and one research article is summarized
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
Analysis of tomato glycoalkaloids by liquid chromatography coupled with electrospray ionization tandem mass spectrometry.
Full text linkSteroidal glycoalkaloids (SGAs) extracted from tomato leaves and berries (Lycopersicon esculentum Mill.) were separated and identified using optimized reversed-phase liquid chromatography with electrospray ionization (ESI) and ion trap mass spectrometry (ITMS). The ESI source polarity and chromatographic conditions were evaluated. The ESI spectra contain valuable information, which
includes the mass of SGAs, the mass of the aglycones, and several characteristic fragment ions. Cleavage at the interglycosidic bonds proximal to the aglycones is the most prominent process
in the ESI process. A protonated molecule, [M+H]+, accompanied by a mixed adduct ion, [M+H+Na]2+, was observed for a-tomatine (i.e., m/z 1034.7 and 528.9) and dehydrotomatine (i.e., m/z 1032.6 and 527.9) in positive ion mode spectra. The structures of these tomato glycoalkaloids were confirmed using tandem mass spectrometry. The identification of a new a-tomatine isomer
glycoalkaloid, named filotomatine (MW 1033), which shares a common tetrasaccharide structure (i.e., lycotretraose) with a-tomatine and dehydrotomatine, and soladulcidine as an aglycone, is described for the first time. It occurs in significant amounts in the extracts of wild tomato foliage. Multistage mass spectrometry both of the protonated molecules and of the doubly charged ions was used for detailed structural elucidation of SGAs. Key fragmentations and regularities in fragmentation pathways are described and the fragmentation mechanisms involved are propose
Traduzione e (auto)commento nei volgarizzamenti italiani antichi
No full textIl contributo si propone di censire e passare in rassegna i volgarizzamenti italiani antichi che presentano, nella propria tradizione manoscritta, un corredo esegetico coevo in volgare. Si propongono quindi riflessioni su alcuni aspetti di tale tipologia testuale, quali il ruolo dell'autore (o degli autori), le fonti dei commenti, la mise en page di testo e commento nei manoscritti, le dinamiche di trasmissione del paratesto, il trattamento editoriale di quest'ultimo nelle edizioni critiche dei volgarizzamenti.
This contribution surveys early Italian vernacular translations whose manuscript tradition preserves a contemporary vernacular exegetical apparatus. It examines key features of this textual typology, including the role of the author (or authors), the sources of the commentaries, the mise en page of text and commentary in the manuscripts, the transmission of paratextual material, and its treatment in modern critical editions of vernacular translations
Riboflavin in dietary sources: separation and detection by CE-LIF
No full textThis article demonstrates the suitability of capillary electrophoresis coupled to laser-induced fluorescence detection for riboflavin determination in common foods and beverages
STUDY OF SUGAR ACIDS SEPARATIONS BY HIGH-PERFORMANCE ANION-EXCHANGE CHROMATOGRAPHY-PULSED AMPEROMETRIC DETECTION USING ALKALINE ELUENTS SPIKED WITH Ba2+, Sr2+, Ca2+ AS ACETATE OR NITRATE SALTS.
No full textThe influence of Ba2+, Ca2+ and Sr2+ ions on the anion-exchange chromatographic separation of some carboxylated sugar acids such as D-gluconic acid, N-acetylneuraminic acid, muramic acid and D-galacturonic, D-mannuronic and D-glucuronic acids was investigated. The chromatographic technique was coupled with pulsed amperometric detection using gold ar a working electrode. Since acidic carbohydrates are strongly retained on the anion-exchange column, acetate and nitrate as counterions were used to regulate retention within 30 min. The addition of alkaline-earth metal ions at a millimolar concentration to the alkaline eluents does impart a noticeable decrease in the retention, especially for N-acetylneuraminic and uronic acids. Complexation of these compounds with free divalent metal ions presumably occurs in the alkaline eluent. The extent of decreased retention is related to each divalent metal ion, and a good correlation was found between the retention modulus (eta = k'/k(o)') and the stability constant of each sugar-metal ion complex. As expected, calcium ion induced a slightly greater retention compared to strontium and barium ions, and this is consistent with the fact that alduronate-calcium complexes are relatively more stable (eta < 1.00). We demonstrate also that upon the addition of Ba2+ and Sr2+ ions in the alkaline eluent, but the same cannot be claimed for calcium-containing eluents, there is a gain in sensitivity for all compounds investigated. The increment on the peak height when the column was eluted with NaOH spiked with Ba(NO3)(2) was generally higher (5-75%) than that with Ba(OAc)(2)
Scrambling of autoinducing precursor peptides investigated by infrared multiphoton dissociation with electrospray ionization and Fourier transform ion cyclotron resonance mass spectrometry
No full textTwo synthetic precursor peptides, H2N-CVGIW and H 2N-LVMCCVGIW, involved in the quorum sensing of Lactobacillus plantarum WCFS1, were characterized by mass spectrometry (MS) with electrospray ionization and 7-T Fourier transform ion cyclotron resonance (ESI-FTICR) instrument. Cell-free bacterial supernatant solutions were analyzed by reversed-phase liquid chromatography with ESI-FTICR MS to verify the occurrence of both pentapeptide and nonapeptide in the bacterial broth. The structural characterization of both protonated peptides was performed by infrared multiphoton dissociation using a continuous CO2 laser source at a wavelength of 10.6 μm. As their fragmentation behavior cannot be directly derived from the primary peptide structure, all anomalous fragments were interpreted as neutral loss of amino acids from the interior of both peptides, i.e., loss of V, G, VG and M, MC, V, CC, from H2N-CVGIW and H 2N-LVMCCVGIW, respectively. Mechanisms of this scrambling are proposed. FTICR MS provides accurate masses of all fragment ions with very low absolute mass errors (<1.6 ppm), which facilitated the reliable assignment of their elemental compositions. The resolving power was more than sufficient to resolve closely isobaric product ions with routine subparts per million mass accuracies. Only the occurrence of pentapeptide was found in the cell-free culture of L. plantarum, grown in Waymouth's medium broth, with a low content of 5.2 ± 2.6 μM by external calibration. Most of it was present as oxidized H2N-CVGIW, that is, the soluble disulfide pentapeptide with a level tenfold higher (i.e., 50 ± 4 μM, n = 3)
Direct electrical communication of cytochrome c and cytochrome b5 at basal plane graphite electrodes modified with lauric acid or laurylamine
No full textDetermination of Proline and Free Monosaccharides in Wine Samples by High-pH Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD)
No full textA sensitive and selective analytical method for the simultaneous separation and quantitative determination of proline and free monosaccharides in wine samples by high-performance anion-exchange
chromatography coupled with pulsed amperometric detection is described. Under optimized experimental conditions, a complete separation was obtained in less than 30 min, using an isocratic elution with 10 mM NaOH and 1 mM Ba(OAc)2. No postcolumn addition of strong bases to the eluent for enhancing detection sensitivity was needed. Upon 25-fold sample dilution and purification to avoid interference of tannins, pigments, and phenolic compounds, the fingerprinting of common monosaccharides (i.e., arabinose, glucose, fructose, galactose, and xylose) and proline in wines, musts, and vinegars can be easily accomplished. The method allows high recovery and satisfies the necessary requirements for accuracy, repeatability, and sensitivity. Values obtained for proline content ranged from 470 to 1190 mg/L in “Aglianico” red wines (mean value, 870 ( 192 mg/L, n ) 21) and from 168 to 286 mg/L in white wines (mean value, 208 ( 32 mg/L, n ) 11). Lower levels were found in musts of red and white grapes, 550 and 87 mg/L, respectively. The lowest content of proline, ca. 10 mg/L, was found both in white and red vinegars
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