1,721,312 research outputs found
Concept of (low-)flow modulation comprehensive two-dimensional gas chromatography under sub-ambient, ambient and supra-ambient pressure outlet conditions
No full textA powerful four-dimensional separation-science tool: on-line liquid chromatography-comprehensive two dimensional gas chromatography-triple quad mass spectrometry
No full textPHOTOACID SWITCHING IN FUSED-RING N-RICH AROMATICS
No full text[1,2,4]triazolo[3,2-c][1,2,4]triazole is a simple fused-ring N-rich aromatic
system, with remarkable properties with respect to acid-base behavior and
tautomerism1-3. Neutral heterobicycles (HL) exhibit amphoteric behaviour
(they can deliver the N−H proton forming the conjugated base L-
and can
accept up to two protons, forming the species H2L+
and H3L++) and show an
unprecedented tautomeric switching upon protonation, as revealed by single
crystal X-ray analysis and confirmed by theoretical calculations4
. By
varying the groups attached at the heterocycle, a remarkable shift of pKai
values, up to 5-6 units, is observed. The studies of the acid-base properties
in the excited state show that the N-H group in neutral triazolo-triazoles has
an intrinsic photobasic behavior. Singly protonated forms of the system
have instead a photoacid behavior. If a photoacid phenol group is attached at
position 7 of the intrinsically photobasic triazolo-triazole unit, the
interaction between the two complementary photoactive functions in the
same molecule is additive, in such a way that in the ground state N-H is
more acid than O-H while the opposite holds in the excited state. So,
between ground and excited state, the acid proton is delivered by different
sites of the same molecule (photoacid switching).
[1] C-H Zhou, Y. Wang,Current Medicinal Chemistry,19 (2012) N.2, 239-
280.
[2] Y. Murti at all, American Journal of Chemistry1 (2011) 42-46.
[3] R. Centore, S. Fusco, A. Capobianco,V. Piccialli, S. Zaccaria, and A.
PelusoEuropean Journal of Organic Chemistry18 (2013) 3721-3728.
[4] R. Centore, C. Manfredi, S. Fusco, C. Maglione, A. Carella, A.
Capobianco, A. Peluso, D. Colonna, A. Di Carlo,Journal of Molecular
Structure 1093 (2015) 119–124
A THERMODYNAMIC STUDY ON THE RESVERATROL-WATER SYSTEM
No full textResearch on the effects of dietary polyphenols on human health has
developed considerably in the past. It strongly supports a role for
polyphenols in the prevention of degenerative diseases, particularly
cardiovascular diseases and cancers1,2. The antioxidant properties of
polyphenols have been widely studied, but it has become clear that the
mechanisms of action of polyphenols go beyond the modulation of
oxidative stress. In nature we can find resveratrol as two diastereoisomers:
(Z)- resveratrol and (E)- resveratrol that presents a major stability3
Fig1.- trans-resveratrolo
In the present work is presented a thermodynamic study on resveratrol in
aqueous solutions. Acid-base properties of resveratrol have been
investigated. The study has been conducted at 25.00 ± 0.02°C, in constant
ionic medium, NaCl 0.5 M/ethanol 4% (v/v) by using potentiometry, UVVis
spectrophotometry (absorption and emission), chromatography (HPLC).
A chemical investigation on the interaction of the resveratrol with metals of
biological interest, such as Mn2+ and Cu2+has also been carried out. The
study indicated the formation of a predominating Me(II)-resveratrol,
mononuclear complexes.
[1] M. Valko, D. Leibfritz, J. Moncol, M. Cronin, M. Mazur, J. Telser,, The
International Journal of Biochemistry & Cell Biology, 39(2007) 44–84
[2] D. Delmas, Virginie Aires, E. Limagne, P. Dutartre, F. Mazue, F.
Ghiringhelli and N. Latruffe, Ann. N.Y. Acad. Sci.,1215 (2011) 48-59
[3] M. Deak and H. Falk, On the Chemistry of the Resveratrol
Diastereomers, Monatshefte feur Chemie, 134(2003)883–888
HO
Chromatographic separation with amperometric detection for the determination of environmental pollutants
No full text
Ion-imprinted polymers as a sustainable strategy for the efficient recovery of lithium ions from wastewater
No full textGoing 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
Biodegradation Potential of Oil-degrading Bacteria Related to the Genus Thalassospira Isolated from Polluted Coastal Area in Mediterranean Sea
Full text linkThree bacterial species related to the genus Thalassospira
(T. lucentensis, T. xianhensis and T. profundimaris), isolated from polluted sediment and seawater samples collected from Priolo Bay (eastern coast of Sicily, Ionian Sea), were analyzed for their biotechnological
potential. For this purpose, the presence of specific catabolic genes
associated to aliphatic and aromatic hydrocarbon metabolism, the
production of biosurfactants and emulsification activity, the capability
to degrade oil-derived linear, branched, cyclic alkanes, and polycyclic
aromatic hydrocarbons (PAHs) were evaluated. Alkane hydroxylase
gene (alkano-monoxygenase alkb and citocrome P450) were present
in genome of all strains, confirming their hydrocarbons degrading
capability. All strains of Thalassospira produced biosurfactants and
showed emulsification activity. The two-dimensional gas chromatography analysis (GC×GC) showed that they were able to degrade oil
fractions with the capacity ranging between 77% and 91%. The data
obtained in this study demonstrated the biodegradation ability of
Thalassospira and suggest that these strains play an important role in
marine contaminated ecosystem
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