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133.
Cristofor Simionescu Severian Dumitriu Marcel Popa Cristina Coman Vlad Artenie 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):677-686
Pepsin was immobilized on BIOZAN R (Hercules) with dicyclohexylcarbodiimide as activator. The reaction product obtained has a protein content of 35–110 mg/g of polymer and a proteolytic activity between 20.85–28.75 μmol tyrosine/L·min·g of polymer). The coupling reaction rate is maximum under the following conditions: pepsin/BIOZAN R ratio = 0.52 g/g, DCCI/BIOZAN R ratio = 0.2 g/g, pH = 3.4, reaction time = 4 h. 相似文献
134.
Michelle Gonçalves Mothé Cheila Gonçalves Mothé Carlos Henrique Monteiro de Carvalho Marcia Cristina Khalil de Oliveira 《Journal of Thermal Analysis and Calorimetry》2013,113(2):525-531
Present study investigates thermal behavior of two heavy crude oils with different °API values by simultaneous thermogravimetry–differential scanning calorimetry–fourier transform infrared spectroscopy (TG–DSC–FTIR), and an evaluation of the chemical element levels present in the oils’ ashes was done by energy dispersive X-ray fluorescence spectrometry. TG and DSC curves were obtained for two samples in nitrogen atmosphere. Among all inorganic components evaluated, the highest concentration in the two oils was SO3. Thus this study may contribute to a better understanding of the thermal behavior of heavy crude oils and their composition. 相似文献
135.
Cristina Bucur Romana Cerc Korošec Mihaela Badea Larisa Calu Mariana Carmen Chifiriuc Nicoleta Grecu Nicolae Stanică Dana Marinescu Rodica Olar 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1287-1295
Novel complexes of type M2LCl4·nH2O (M: Ni, n = 4; M: Cu, n = 2.5 and M: Zn, n = 1.5; L: ligand resulted from 1,3-phenylenediamine, 3,6-diazaoctane-1,8-diamine, and formaldehyde one-pot condensation) were synthesized and characterized. The ligand was also isolated and characterized. The complexes features have been assigned from microanalytical, electrospray ionization tandem mass spectrometry, IR, UV–vis, 1H NMR, and EPR spectra as well as magnetic data at room temperature. Simultaneous thermogravimetric/dynamic scanning calorimetry/evolved gas analysis measurements were performed to evidence the nature of the gaseous products formed in each step. Processes as water elimination, fragmentation, and oxidative degradation of the organic ligand as well as chloride elimination were observed during the thermal decomposition. The final product of decomposition was metal(II) oxide except for copper complex where CuCl remained also in the oxide network. The complexes exhibited an improved antibacterial activity in comparison with the ligand concerning both planktonic as well as biofilm-embedded cells. 相似文献
136.
Immobilized purine nucleoside phosphorylase from Schistosoma mansoni for specific inhibition studies
Marcela Cristina de Moraes Carmen L. Cardoso Quezia B. Cass 《Analytical and bioanalytical chemistry》2013,405(14):4871-4878
The parasite Schistosoma mansoni (Sm) depends exclusively on the salvage pathway for its purine requirements. The enzyme purine nucleoside phosphorylase (PNP) is, therefore, a promising target for development of antischistosomal agents and an assay for screening of inhibitors. To enable this, immobilized SmPNP reactors were produced. By quantification of hypoxanthine by liquid chromatography, kinetic constants (K M) for the substrate inosine were determined for the free and immobilized enzyme as 110 ± 6.90 μmol?L ?1 and 164 ± 13.4 μmol?L ?1 , respectively, indicating that immobilization did not affect enzyme activity. Furthermore, the enzyme retained 25 % of its activity after four months. Non-Michaelis kinetics for the phosphate substrate, and capacity for Pi-independent hydrolysis were also demonstrated, despite the low rate of enzymatic catalysis. Use of an SmPNP immobilized enzyme reactor (IMER) for inhibitor-screening assays was demonstrated with a small library of 9-deazaguanine analogues. The method had high selectivity and specificity compared with screening by use of the free enzyme by the Kalckar method, and furnished results without the need for verification of the absence of false positives. Figure
A cartoon illustrating the online SmPNP-IMER activity assay 相似文献
137.
Francesca Bettazzi Ezat Hamid-Asl Carla Lucia Esposito Cristina Quintavalle Nello Formisano Serena Laschi Silvia Catuogno Margherita Iaboni Giovanna Marrazza Marco Mascini Laura Cerchia Vittorio De Franciscis Gerolama Condorelli Ilaria Palchetti 《Analytical and bioanalytical chemistry》2013,405(2-3):1025-1034
MicroRNAs (miRNAs, miRs) are naturally occurring small RNAs (approximately 22 nucleotides in length) that have critical functions in a variety of biological processes, including tumorigenesis. They are an important target for detection technology for future medical diagnostics. In this paper we report an electrochemical method for miRNA detection based on paramagnetic beads and enzyme amplification. In particular, miR 222 was chosen as model sequence, because of its involvement in brain, lung, and liver cancers. The proposed bioassay is based on biotinylated DNA capture probes immobilized on streptavidin-coated paramagnetic beads. Total RNA was extracted from the cell sample, enriched for small RNA, biotinylated, and then hybridized with the capture probe on the beads. The beads were then incubated with streptavidin–alkaline phosphatase and exposed to the appropriate enzymatic substrate. The product of the enzymatic reaction was electrochemically monitored. The assay was finally tested with a compact microfluidic device which enables multiplexed analysis of eight different samples with a detection limit of 7 pmol L?1 and RSD?=?15 %. RNA samples from non-small-cell lung cancer and glioblastoma cell lines were also analyzed. 相似文献
138.
Patrícia Santiago de Oliveira Patricio Iaci Miranda Pereira Natália Cristina Ferreira da Silva Eliane Ayres Fabiano Vargas Pereira Rodrigo Lambert Oréfice 《European Polymer Journal》2013
Polyurethane waterborne synthesis was performed using a two-step method, commonly referred to as a prepolymer method. Nanocomposites based on waterborne polyurethane and cellulose nanocrystals were prepared by the prepolymer method by altering the mode and step in which the nanofillers were incorporated during the polyurethane formation. The morphology, structural, thermal, and mechanical properties of the resulting nanocomposite films were evaluated by Fourier transform infrared spectroscopy (FTIR), small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), and tensile tests. FTIR results indicated that the degree of interaction between the nanofillers and the WPU through hydrogen bonds could be controlled by the method of cellulose nanocrystal incorporation. Data obtained from SAXS experiments showed that the cellulose nanocrystals as well as the step of the reaction in which they are added influenced the morphology of the polyurethane. The reinforcing effect of CNCs on the nanocomposites depends on their morphology. 相似文献
139.
The unconventional methodology for the non-epimerizable cycloacetalization of optically active (1S,2S)-2-amino-1-(4-nitrophenyl)propane-1,3-diol (p-nitrophenylserinol) (condensed H2SO4 96% as solvent and catalyst, i.e., sulfuric transacetalization) producing (2R,4S,5S) diamino-1,3-dioxanes was enlarged by the use of N-protected forms of 2,2-dimethoxyethylamine (DMEA, aminoacetaldehyde dimethylacetal). Conversely, N-protected derivatives of p-nitrophenylserinol were successfully cyclocondensed with DMEA in the same sulfuric conditions. N-Functionalization of DMEA upon treatment with trimesic acid trichloride and cyanuric chloride yielded the corresponding triple amide and melamine, respectively. Their adapted sulfuric transacetalization in triplicate in reaction with arylserinols (aryl: phenyl, p-nitrophenyl) afforded a new series of optically active tripodands. 相似文献
140.
Transition metal nitrides and carbides (MN/MC) are intriguing materials due to their combination of properties that place them between high-performance ceramics and pure metals. Recent progress in easier synthetic routes toward their production as bulk or nanostructured materials explains the current surge in sustained attention such progress has been receiving. After progressing toward easier syntheses of MN/MC nanosystems as pure phases, coupling MN/MC with a second phase for the production of hybrids and nanocomposites is considered a next important step in the development of these nanosystems. The coupled phase can simply be a different nitride or carbide; it also can be a polymer, a poly(ionic liquid) or a carbon phase, just to give a few examples. The combination of these phases with MN/MC nanoparticles could lead to multifunctional materials. The aim of the present review is to show how far the research concerning the production of MN/MC-based nanocomposites has progressed, especially in terms of controlled composition, morphology and properties. We discuss the most intensely investigated systems and related motivations, as well as partially unexplored yet appealing alternative materials. 相似文献