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161.
Alessandra Bua Paola Molicotti Matthew Gavino Donadu Donatella Usai Lam Son Le Thi Trung Thu Tran 《Natural product research》2020,34(10):1494-1497
AbstractThe increasing incidence of resistance in tuberculosis and in atypical mycobacterial infections has prompted the search for alternative agents. We explored the antimycobacterial activity of Melaleuca cajuputi essential oil against tubercular and non tubercular mycobacterials isolates. The good activity observed towards M. cajuputi indicated that this essential oil might represent a promising antimicrobial agents, particularly in the management of microbial resistance. 相似文献
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163.
The interaction of VO(2+) ion with ligands of biological interest that are present in important metabolic pathways--2-oxopropanoic acid (pyruvic acid, pyrH), 3-hydroxy-2-oxopropanoic acid (3-hydroxypyruvic acid, hydpyrH), oxobutanedioic acid (oxalacetic acid, oxalH(2)), (S)-hydroxybutanedioic acid (l-malic acid, malH(2)), and 2,3-dihydroxy-(E)-butanedioic acid (dihydroxyfumaric acid, dhfH(2))--was described. Their complexing capability was compared with that of similar ligands: 3-hydroxy-2-butanone (hydbut) and 3,4-dihydroxy-3-cyclobutene-1,2-dione (squaric acid, squarH(2)). All of these ligands (except l-malic acid) exhibit keto-enol tautomerism, and the presence of a metal ion can influence such an equilibrium. The different systems were studied with electron paramagnetic resonance (EPR) and UV-vis spectroscopies and with pH potentiometry. Density functional theory (DFT) methods provide valuable information on the relative energy of the enol and keto forms of the ligands both in the gas phase and in aqueous solution, on the geometry of the complexes, and on EPR and electronic absorption parameters. The results show that most of the ligands behave like α-hydroxycarboxylates, forming mono- and bis-chelated species with (COO(-), O(-)) coordination, demonstrating that the metal ion is able to stabilize the enolate form of some ligands. With dihydroxyfumaric acid, the formation of a non-oxidovanadium(IV) complex, because of rearrangement of dihydroxyfumaric to dihydroxymaleic acid (dhmH(2)), can be observed. With 3-hydroxy-2-butanone and 3,4-dihydroxy-3-cyclobutene-1,2-dione, complexation of VO(2+) does not take place and the reason for this behavior is explained by chemical considerations and computational calculations. 相似文献
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166.
Severyn Salis Nicola Rubattu Federica Rubattu Maurizio Cossu Andrea Sanna Giannina Chessa 《Molecules (Basel, Switzerland)》2022,27(19)
The presence of unauthorized substances, such as residues of veterinary medicines or chemical contaminants, in food can represent a possible health concern. For this reason, a complete legislative framework has been established in the European Union (EU), which defines the maximum limits allowed in food and carries out surveillance programs to control the presence of these substances. Official food control laboratories, in order to ensure a high level of consumer protection, must respond to the challenge of improving and harmonizing the performance of the analytical methods used for the analysis of residues of authorized, unauthorized, or prohibited pharmacologically active substances. Laboratories must also consider the state of the art of the analytical methodologies and the performance requirements of current legislation. The aim of this work was to develop a multiresidue method for the determination of antibiotics in milk, compliant with the criteria and procedures established by Commission Implementing Regulation (EU) 2021/808. The method uses an LC-Orbitrap-HRMS for the determination of 57 molecules of antibiotic and active antibacterial substances belonging to different chemical classes (beta-lactams, tetracyclines, sulfonamides, quinolones, pleuromutilins, macrolides, and lincosamides) in bovine, ovine, and goat milk samples. It provides a simple and quick sample pretreatment and a subsequent identification phase of analytes, at concentrations equal to or lower than the maximum residual limit (MRL), in compliance with Commission Regulation (EU) 2010/37. The validation parameters: selectivity, stability, applicability, and detection capability (ccβ), are in agreement with the requirements of Commission Implementing Regulation (EU) 2021/808 and demonstrated the effectiveness of the method in detecting veterinary drug residues at the target screening concentration (at the MRL level or below), with a false positive rate of less than 5%. This method represents an effective solution for detecting antibiotics in milk, which can be successfully applied in routine analyses for official food control plans. 相似文献
167.
Willem M. Albers Sanna Auer Hannu Helle Tony Munter Inger Vikholm-Lundin 《Colloids and surfaces. B, Biointerfaces》2009,68(2):193-199
Antibody Fab′-fragments have been immobilised on hydrophilic gold by direct self-assembly, and embedded in a matrix of non-ionic hydrophilic polymers, tris(hydroxymethyl)methylacrylamide, carrying lipoate terminal linking groups. Different polymers were synthesised, and co-adsorbed or post-adsorbed between the antibody fragments in order to optimise the antigen binding. Various factors were investigated that influence the activity of the immobilised Fab′-fragments for binding of the antigen, human IgG. The Fab′-fragments were immobilised in dense layers close to monolayer coverage, and the stoichiometric efficiency of immobilisation was up to 30%, with the human IgG also approaching monolayer coverage. The cleaning of the gold surface was a crucial factor in preservation of activity. Besides the usual treatment in hot ammonia/peroxide solution, hot DMSO appeared to be highly effective as a cleaning agent. 相似文献
168.
Antti?Laakso Mihail?Dumitrescu Jukka?Viheri?l? Jarkko?Telkk?l? Juha?Tommila Kimmo?Haring Tomi?Leinonen Sanna?Ranta Markus?Pessa 《Optical and Quantum Electronics》2009,41(1):11-16
The paper presents a simulation-based analysis of laterally-corrugated ridge-waveguide distributed feedback semiconductor
lasers emitting at 980 nm. The simulations were performed using software developed in-house and the PICS3D software package
from Crosslight Software Inc. The effects of the corrugation geometry, phase-shift section, and mirror reflectivities on single
longitudinal mode operation are discussed. The lasers, designed along the guidelines derived from the simulation results,
were fabricated by using molecular beam epitaxy for wafer growth and low-cost nano-imprint lithography. They exhibited stable
single-mode operation with up to 50 dB side-mode suppression ratio. 相似文献
169.
Dr. Giuseppe Di Natale Dr. Katalin Ősz Dr. Csilla Kállay Dr. Giuseppe Pappalardo Dr. Daniele Sanna Prof. Giuseppe Impellizzeri Prof. Imre Sóvágó Prof. Enrico Rizzarelli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3751-3761
Characterization of the copper(II) complexes formed with the tetraoctarepeat peptide at low and high metal‐to‐ligand ratios and in a large pH range, would provide a breakthrough in the interpretation of biological relevance of the different metal complexes of copper(II)‐tetraoctarepeat system. In the present work, the potentiometric, UV/Vis, circular dichroism (CD), and electron paramagnetic resonance (EPR) studies were carried out on copper(II) complexes with a PEG‐ylated derivative of the tetraoctarepeats peptide sequence (Ac‐PEG27‐(PHGGGWGQ)4‐NH2) and the peptide Ac‐(PHGGGWGQ)2‐NH2. Conjugation of tetraoctarepeat peptide sequence with polyethyleneglycol improved the solubility of the copper(II) complexes. The results enable a straightforward explanation of the conflicting results originated from the underestimation of all metal–ligand equilibria and the ensuing speciation. A complete and reliable speciation is therefore obtained with the released affinity and binding details of the main complexes species formed in aqueous solution. The results contribute to clarify the discrepancies of several studies in which the authors ascribe the redox activity of copper(II)‐tetraoctarepeat system considering only the average effects of several coexisting species with very different stoichiometries and binding modes. 相似文献
170.
Valeria Alzari Daniele Nuvoli Roberta Sanna Laura Peponi Massimo Piccinini Silvia Bittolo Bon Salvatore Marceddu Luca Valentini Jose Maria Kenny Alberto Mariani 《Colloid and polymer science》2013,291(11):2681-2687
Nanocomposite hydrogels of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) containing graphene were prepared by radical polymerization. Their swelling properties in response to ionic strength and electrical stimuli were assessed. Graphene was obtained through an easy and convenient method lately developed by our research group, which consists in the exfoliation of graphite by sonicating it in a proper solvent medium. It was found that the graphene content influences the swelling properties of hydrogels; in particular, those containing graphene swell more than the filler-free ones; graphene content influences also the swelling ratio variation between the swollen and deswollen states. 相似文献