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11.
The study of the ageing of two paper types was performed on monitoring it during a simulated process by means of the measure of the photocatalytic degradation of the paper cellulose. Such evaluation was possible due to the combined responses of a photosensor based on titanium dioxide in suspension, of an enzymatic biosensor based on superoxide dismutase (SOD), of a specific conductivity sensor and of an enzymatic biosensor based on glucose oxidase. 相似文献
12.
Giuseppe Trapani Andrea Latrofa Antonia Reho Massimo Franco Gaetano Liso 《Journal of heterocyclic chemistry》1992,29(5):1155-1159
The title compounds 3a-j together with the N-alkylacylketene S,N-acetals 12a-j were obtained by reaction of N,N'-dialkyldithiodianilines with β-ketoesters compounds. A possible reaction pathway is suggested. 相似文献
13.
Silvio Aime Mauro Botta Giancarlo Cravotto Luca Frullano GiovanniB. Giovenzana Simonetta GeninattiCrich Giovanni Palmisano Massimo Sisti 《Helvetica chimica acta》2005,88(3):588-603
Four new ligands for lanthanide ions based on the H3do3a (=1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid) structure and bearing one N‐sulfonylacetamide arm were synthesized, i.e., H4dota‐NHSO2R=10‐{2‐[(R)sulfonylamino]‐2‐oxoethyl}‐1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acids 1a – e . A 15N‐NMR study of the 15N‐labelled Eu3+ complex of one such ligands, 1d , showed that the coordination of the N‐sulfonylacetamide arm involves the carbonyl O‐atom rather than the N‐atom. The relaxometric properties of the corresponding Gd3+ complexes were investigated as a function of pH and temperature. These complexes have relaxivities in the range 4.5–5.3 mM ?1 s?1, at 20 MHz and 25°, and are characterized by a single H2O molecule in their inner coordination sphere. The mean residence lifetime of this molecule is relatively long (500–700 ns) compared to other anionic complexes. The slow rate of H2O exchange can be justified by the extensive delocalization of the negative charge on the N‐sulfonylacetamide arm. The long residence time of the coordinated H2O allowed the observation of the effect of the prototropic exchange on the relaxivity. The study of the interaction between the complex [Gd( 1e )]‐ and HSA revealed a weak affinity constant highlighting the importance of a localized negative charge on the complex to promote a strong interaction with the protein. 相似文献
14.
Cametti M Nissinen M Dalla Cort A Mandolini L Rissanen K 《Chemical communications (Cambridge, England)》2003,(19):2420-2421
Uranyl-salophen complexes endowed with aromatic side arms behave as very efficient ditopic receptors towards tetralkylammonium halides as a result of a combination of Lewis acid-base and cation-pi interactions. 相似文献
15.
[reaction: see text] A laser flash photolysis study has been carried out to assess solvent effects on the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals. The rearrangement rate constant k decreases by increasing solvent polarity and an excellent correlation with negative slope is obtained between log k and the solvent polarity parameter E(T)N. These evidences are in full agreement with the previous indication that the extent of internal charge separation decreases on going from the starting 1,1-diarylalkoxyl radical to the transition state. 相似文献
16.
Hydrophobic interaction chromatography coupled online with chemical vapour atomic fluorescence spectrometry (HIC-CVGAFS) has been optimized for the analysis of thiolic proteins in denaturing conditions. Proteins are pre-column simultaneously denatured and derivatized in phosphate buffer solution containing 8.0 mol dm−3 urea and p-hydroxymercurybenzoate (PHMB) and the derivatized denatured proteins are separated on a silica HIC Eichrom Propyl column in the presence of 8.0 M urea in the mobile phase. Post-column online reaction of derivatized denatured proteins with bromine, generated in situ by KBr/KBrO3 in HCl medium, allowed the fast conversion of the uncomplexed PHMB and of the PHMB bound to proteins to inorganic mercury also in presence of urea. Hg2+, present in solution as Hg2+-urea complex, is selectively detected by AFS in a Ar/H2 miniaturized flame after sodium borohydride reduction to Hg. Under optimized conditions, online bromine treatment gives a 100±2% recovery of both free and protein-complexed PHMB. Denatured glyceraldehyde-3-phosphate dehydrogenase, aldolase, lactate dehydrogenase, trioso phosphate isomerase and β-lactoglobulin have been examined. As the sensitivity and limit of detection of proteins in the HIC-CVGAFS apparatus depends on number of SH groups reacting with PHMB, the denaturation process, which increases the number of PHMB-reactive thiolic groups in proteins, improves the analytical performances of the described system in protein analysis. The detection limit for the denatured proteins examined was found in the range of 10−10-10−12 mol dm−3, depending on the considered protein, with linear calibration curves spanning over four decades of concentration. 相似文献
17.
Amirhossein Nazhand Alessandra Durazzo Massimo Lucarini Maria Alessandra Mobilia Besma Omri 《Natural product research》2020,34(1):110-121
AbstractTaxol is one of the anticancer drugs synthesized naturally in the evergreen Taxus brevifolia forest tree belonging to the yew family (Taxaceae) growing on the Pacific. There are reportedly evidence for treating ovarian, breast and lung cancers through this drug given its unique structural and functional features. Extraction of this drug from yew trees bark is one of the most common ways of producing this drug, but 3000 trees are needed to obtain a kilogram of Taxol. Hence, further attention has recently been attracted to the metabolic engineering strategies, including, engineering cellular metabolism of microorganisms and their optimization. Accordingly, the present paper article was aimed to review recent advances in elevating the production and commercialization of Taxol through metabolic engineering techniques. 相似文献
18.
Abstract— The effects of repeated UV exposure on the skin of the European crested newt, Triturus cristatus carnifex , have been investigated. The animals were irradiated 3 times per week with a Westing-house FS40T12 fluorescent sun lamp (wavelength spectrum 275–350 nm). Two groups of animals received the same total fluence of 1.3 × 105 J/m2 in single fluences of either 1570 J/m2 (group A) or 9430 J/m2 (group C), and one group received a total fluence of 2.6 × 105 J/m2 in single fluences of 4710 J/m2 (group B). All the animals were killed 7 months after the first UV exposure, but at different intervals after the last exposure. Striking epidermal hyperplasia was found in the newts irradiated at the lower fluence rate (group A). In the animals given the higher total fluence (group B), the most prominent skin changes were dermal fibrosis and irregular thinning and thickening of the epidermis. No significant skin changes were found in group C., in which if there had been UV lesions, they had been repaired during the 5 month interval between the last irradiation and the killing of the animals. No skin tumors developed in any experimental group. 相似文献
19.
Lara BianchiCarlo Dell'Erba Massimo MaccagnoAngelo Mugnoli Marino NoviGiovanni Petrillo Fernando SancassanCinzia Tavani 《Tetrahedron》2003,59(51):10195-10201
1-(Methyl-p-tolyl-amino)-3-phenoxy-2-azetidinones 4-COX and 4-R substituted (COX: X=Me, Et, Ph, NMe2, NEt2, OBut; R=Me, Et, Ph) were smoothly prepared from the corresponding α-(methyl-p-tolyl)hydrazonylated ketones, amides and esters via [2+2] cycloaddition with phenoxyketene. The reaction was generally high-yielding and diastereoselective, leading to β-lactams with a cis relationship between the PhO and the COX moieties, except for R=Ph, where an opposite stereoselectivity was instead observed. The azetidinones represent interesting intermediates which couple protection at N(1) and functionalization at position 4 of the ring. Deprotection of N(1) can be easily attained by oxidative N-N cleavage with magnesium monoperoxyphthalate. 相似文献
20.
The kinetics of the interaction between Gemcitabine (a new anticancer drug) and phospholipid membrane models was investigated. This kind of study is of particular importance both in hypothesizing the interaction of Gemcitabine with mammalian cell membranes and in evaluating the potentiality of liposomes as a Gemcitabine delivery system. Unilamellar (LUV) and multilamellar (MLV) membrane models were made up of dimyristoylphosphatidylcholine (DMPC), dimyristoylphosphatidic acid sodium salt (DMPA), or a DMPC-DMPA mixture (1:1 molar ratio). Gemcitabine-phospholipid vesicle interaction was studied by differential scanning calorimetry (DSC) measurements performed at different time intervals. The findings showed slower permeation kinetics of Gemcitabine through MLV than LUV which, at the same lipid/water ratio, are characterized by a larger lipid surface in contact with the drug aqueous solution. Another interesting difference between LUV and MLV is the onset of a transient two-peak structure during the DSC scans of MLVs. The effect is due to the unequal distribution of the drug between the outer and inner bilayers of the multilamellar vesicles during the permeation kinetics. At equilibrium the two-peak structure merges into a unique peak. This finding may provide useful information about the lipid bilayer permeability in model membranes. 相似文献