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61.
Chalcone, flavone, and arylideneflavanone derivatives bearing one or two 3,5-di-tert-butyl-4-hydroxyphenyl groups were synthesized from 2′,4′-dihydroxyacetophenone and 3,5-di-tert-butyl-4-hydroxybenzaldehyde. These flavonoids were converted into the corresponding malonates and then reacted with C60 to yield the title compounds. The O-H bond dissociation enthalpies (BDE) and the chain-breaking antioxidant activity of the flavonoid derivatives and the corresponding C60 conjugates were evaluated. These results are consistent with the phenolic moiety being the main responsible for the reaction with peroxyl radicals, while the C60 part of the molecule acts synergically by trapping alkyl radicals under reduced O2 partial pressure. These novel C60-flavonoid conjugates are therefore promising leads for broad-spectrum radical scavengers. 相似文献
62.
Parviz Holakooei Ferruccio Carlo Petrucci Renzo Tassinari Carmela Vaccaro 《X射线光谱测定》2013,42(2):105-115
An outstanding style of Persian tilework, which emerged from the north‐eastern Iran in the 15th century, was extensively used for decorating architectural facades during the Safavid period (from the 16th through the 18th century). This type of tilework, the so‐called haft rang, technically comprises of forming a clay body and firing two glazed layers on top of the body. In the present paper, the first analytical data concerning haft rang tiles is provided. To do so, forty three samples of Safavid haft rang bodies were analysed by wavelength dispersive x‐ray fluorescence (WDXRF) and the obtained data were handled by principal component analysis (PCA). The results showed that the 17th century haft rang tiles wherever found are local products; that is, Safavid tile‐makers have used local clay sources to make the bodies of haft rang tiles. The analytical data also showed that old tileworks, in general sense, can be simply replaced by newly manufactured tiles or, at least, all tilework revetments in an individual edifice might not have been produced in an identical workshop. Moreover, WDXRF was used as an accurate and precise method to determine the chemical composition and to support compositional classification in provenance studies and can be considered as a reliable alternative for studying the provenance of archaeological ceramics. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
63.
P. Carloni L. Greci E. Maurelli P. Stipa M. Wozniak G. Marrosu R. Petrucci A. Trazza 《Research on Chemical Intermediates》1993,19(7):643-656
The reduction of tetrazolium salts (namely INT, MTT and BNT) with NADH in the presence of catalytic amounts of PMS (5-methylphenazonium
methylsulfate) was studied, and the influence of oxygen on the system was considered. The redox potentials of all the investigated
compounds, the kinetic measurements, as well as the application of the Marcus theory confirmed that PMS and tetrazolium ions
are reduced by NADH through an inner-sphere mechanism. The EPR investigations led to the detection of all possible radical
species coming from PMS and tetrazolium ions and are in agreement with a mechanism which excludes any role of oxygen in the
system NADH/PMS/tetrazolium for the formation of formazan. 相似文献
64.
65.
Summary A method, based on slurrying of solids, is described for the direct, routine flame atomic absorption (flame AAS) and inductively-coupled plasma atomic emission (ICP-AES) spectroscopic trace determination of Cu, Zn and Cd in solid biological samples. The sample powder (particles < 20 m) — between 40 and 100 mg — is firstly wetted with a 0.5% sodium hexametaphosphate solution and is then dispersed in a 5.6% v/v nitric acid solution. Both magnetic and ultrasonic stirring were evaluated. The latter proved to be the more effective especially when dealing with the higher concentration suspensions. The suspension is then aspirated directly into the spectrometer. Direct comparison with aqueous calibration standards can be used in all cases.All samples were analyzed with an accuracy of ±10% and a precision (relative standard deviation) of better than 7%. The limits of detection were as low as 2.0×10–2 g/g for zinc. Sensitivities, reported as concentration required to give a 0.0044 absorbance signal, were as low as 2.4×10–2 g/g for zinc. The advantages of this method are its simplicity, low cost, speed of analysis and simple and rapid calibration.
Bestimmung von Cu, Zn und Cd in festen Suspensionen biologischer Proben durch Flammen-AAS und ICP-AES
Zusammenfassung Zur Spurenbestimmung von Cu, Zn und Cd in biologischen Proben durch Flammen-AAS und ICPAES wird eine Aufschlämmung von Festteilchen benutzt. Die pulverisierte Probe (mit Teilchengrössen < 20 um, 40–100 mg) wird zunächst mit 0,5%iger Natriumhexametaphosphatlösung benetzt und dann in 5,6%iger Salpetersäurelösung dispergiert. Besonderes bei höheren Konzentrationen hat sich Ultraschall-Rühren besser bewährt als magnetische Methoden. Die Suspension wird direkt in das Gerät eingeführt. In allen Fällen wurde der Vergleich mit wässrigen Standardlösungen durchgeführt. Die Richtigkeit betrug 10%, die Präzision (relative Standardabweichung) war besser als 7%. Die Nachweisgrenze lag für Zink bei 2×10–2 g/g, die Empfindlichkeit (Extinktion 0,0044) bei 1,8×10–2 g/g. Die Vorteile des Verfahrens sind: Einfachheit, niedrige Kosten, Schnelligkeit und einfache sowie rasche Eichung.相似文献
66.
67.
Francesco Petrucci Nicola Violante Oreste Senofonte Marco De Gregorio Alessandro Alimonti Sergio Caroli Giovanni Forte Antonio Cristaudo 《Microchemical Journal》2004,76(1-2):131
The increasing industrial use of platinum-group elements (PGEs), namely Ir, Pd, Pt and Rh, and related allergies such as rhinitis, conjunctivitis, asthma, urticaria and contact dermatitis, have led to a growing need to monitor selected populations of exposed workers. In this study, the levels of PGEs were measured in indoor airborne particulate matter and in biological samples taken from employees of a plant where car catalytic converters are produced and precious metals are recovered from spent carbon catalysts. The development of an analytical procedure based on quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) for the analysis of PGEs in airborne particulate matter and on sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) for the analysis of PGEs in blood, serum, urine and hair is described. For airborne particulate matter deposited on filters, the limits of detection (LoDs) were found to be 0.006 ng m−3, 0.020 ng m−3, 0.018 ng m−3 and 0.006 ng m−3 for Ir, Pd, Pt and Rh, respectively. Repeatability of measurements ranged from 1.8 to 8.5%, while recovery was in the range from 92 to 102%. For biological samples LoDs in blood, serum, urine and hair ranged from (in ng l−1) 0.2–0.6 for Ir, 5–10 for Pd, 1–3 for Pt and 2–3 for Rh. For all biological materials, the repeatability varied from 1.1 to 12% for the four elements. Recovery data for the determination of PGEs in biological matrices were found to range from 84.0 to 107.8%. The method was applied to the determination of either total or respirable airborne PGEs collected from five different work areas in the plant. The difference between areas with high and low exposure correlates closely with metal levels in hair, blood and urine. The correlation coefficients between Pt in airborne particulate matter and Pt in biological materials was 0.994, 0.991 and 0.970 for blood, hair and urine, respectively. 相似文献
68.
Mario Bianchi Piero Frediani Ugo Matteoli Gloria Menchi Franco Piacenti Giorgio Petrucci 《Journal of organometallic chemistry》1983,259(2):207-214
The behaviour of the [Ru2(CO)4(CH3COO)2]n/tributylphosphine/acetic acid system has been investigated as a function of reaction conditions and molar ratios of reactants. Tricyclohexylphosphine and triethylphosphite were also used as ligands and investigation was extended to the related oxalic, malonic, succinic, glutaric and adipic acid derivatives. These derivatives were isolated and characterized in view of their possible role as catalysts in the homogeneous hydrogenation of carboxylic acids in the presence of phosphine- or phosphite-substituted ruthenium carbonyl derivatives. 相似文献
69.
Armstrong TA Bettoni D Bharadwaj V Biino C Borreani G Broemmelsiek D Buzzo A Calabrese R Ceccucci A Cester R Church MD Dalpiaz P Dalpiaz PF Dibenedetto R Dimitroyannis D Fabbri MG Fast JE Gianoli A Ginsburg CM Gollwitzer KE Hahn AA Hasan MA Hsueh SY Lewis RA Luppi E Macrí M Majewska A Mandelkern MA Marchetto F Marinelli M Marques JL Marsh W Martini M Masuzawa M Menichetti E Migliori A Mussa R Palestini S Pallavicini M Pastrone N Patrignani C Peoples J Pesando L Petrucci F Pia MG Pordes S 《Physical review letters》1993,70(9):1212-1215
70.
The influence of humic substances on the electrochemical treatment of solutions resulting from the remediation of atrazine contaminated soil has been investigated. In particular the effect on the hydrogen peroxide production stage and the effect on the hydroxyl radical oxidation treatment have been separately studied. In order to quickly assess the possible inhibition of the removal, an inorganic system has been adopted as a standard system. The results confirm the validity of electrochemical technologies also for the treatment of a real effluent where a matrix effect is expected since the organic matter content affects only the hydrogen peroxide production. 相似文献