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81.
Martha Lomeli Luisa Maria Flores-Velez Imelda Esparza Roberto Torres Octavio Domínguez 《Journal of the American Ceramic Society》2009,92(7):1526-1533
The present work represents preliminary results concerning the effect of nanometric CaF2 particles on the sintering behavior of kaolin. The nanoparticles were synthesized using aqueous solutions of CaCl2 dissolved with an organic dispersant and HF. The morphology and particle size of the obtained nanoparticles were square-like, having a mean length of 25 nm. Kaolin was mixed with different amounts of nanometric CaF2 (from 0.625 to 5.0 wt%) and the mixtures were milled, pressed, and sintered. From sintering experiments, it was observed that additions of CaF2 nanoparticles in kaolin clay could shift the phase transition temperatures to lower values. Specifically, the densification temperature could be reduced by almost 150°C when 2.5 wt% of CaF2 was incorporated. Besides, adding 1.25% of nanometric CaF2 can achieve that compressive strength augments from 125 to 185 MPa in kaolin samples sintered at 1200°C, meaning an improvement of 40% in the properties of the final material. 相似文献
82.
Olga Luisa Tavano 《LWT》2008,41(7):1244-1251
The chickpea vicilin-like globulin was isolated and chromatographed on Sepharose CL-6B and Sephacryl S-300. The native globulin with a molecular weight of 140 kDa was resolved in Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in seven polypeptide bands in the range of 12.4-67 kDa. The solubility profile of the protein in water and NaCl solutions was typical of a legume globulin. The purified vicilin-like globulin, native and heated, was hydrolyzed by pepsin, trypsin and chymotrypsin. The hydrolysis patterns indicated that the native vicilin-like protein was only partially degraded by the enzymes in comparison with casein. Heating increased its susceptibility to hydrolysis relative to the native form, for all the enzymes. However, the results obtained by the pH-drop method revealed that the in vitro digestibility of the vicilin-like protein was not altered by heating, while 11S-like and total globulins suffered a small increase, indicating that the structural characteristics of storage globulins may be important factors limiting the protein digestion. 相似文献
83.
Nivia Maria Streit Luisa Helena Rychecki Hecktheuer Marta Weber do Canto Carlos Augusto Mallmann Letícia Streck Thaylise Vey Parodi Liana Pedrolo Canterle 《Food chemistry》2007,102(3):560-564
Erva-mate (Ilex paraguariensis St. Hil.) is a native species from temperate regions of South America, such as Brazil, Paraguay, and Argentina, that is consumed as a beverage known as mate. The objective of this research was to determine the content of caffeic acid, catechin, chlorogenic acid, caffeine, and gallic acid in mate to explain their influence in beverage taste and sensory differences between native and reforested plants, as well as between beverages from plants of different regions of Brazil (Santa Catarina and Rio Grande do Sul states). Compounds were determined by HPLC and results were related to a sensory evaluation performed by trained tasters. Tasters considered the beverage from reforested plants to be more bitter than the beverage from native plants. Beverages from reforested plants had significantly higher caffeic acid and lower catechin, chlorogenic acid, caffeine, and gallic acid content than native plants. Beverages from plants of Santa Catarina state had significantly higher catechin, caffeine, and gallic acid content than plants from Rio Grande do Sul state. 相似文献
84.
A. Clara Grosso Monya M. Costa Luisa Ganço Ana L. Pereira Generosa Teixeira José M.G. Lavado A. Cristina Figueiredo José G. Barroso Luis G. Pedro 《Food chemistry》2007,102(4):1083-1088
The essential oils, isolated by hydrodistillation and distillation-extraction, from the aerial parts of different populations of Pterospartum tridentatum collected during the flowering phase, at different locations in Portugal, were analysed by GC and GC–MS. All the P. tridentatum populations studied afforded a yellowish oil in a yield <0.05% (v/w). cis-Theaspirane (2–14%), trans-theaspirane (2–17%) and octen-3-ol (2–37%) were, in variable amounts, the dominant components of the oils. Cluster analysis of the essential oil compositions from the nine populations studied, confirmed a major chemical variability. 相似文献
85.
Heinis Christian; Huber Adrian; Demartis Salvatore; Bertschinger Julian; Melkko Samu; Lozzi Luisa; Neri Paolo; Neri Dario 《Protein engineering, design & selection : PEDS》2001,14(12):1043-1052
Phage display has been shown to facilitate greatly the selectionof polypeptides with desired properties by establishing a directlink between the polypeptide and the gene that encodes it. However,selection for catalytic activities displayed on phage remainsa challenge, since reaction products diffuse away from the enzymeand make it difficult to recover catalytically active phageenzymes.We have recently described a selection methodology in whichthe reaction substrate (and eventually the reaction product)is anchored on calmodulin-tagged phageenzymes by meansof a calmodulin binding peptide. Phage displaying a catalyticactivity are physically isolated by means of affinity reagentsspecific for the product of reaction. In this study, we investigatedthe efficiency of selection for catalysis by phage display,using a ligase (the Escherichia coli biotin ligase BirA) andan endopeptidase (the rat trypsin His57 相似文献
86.
Regioregular azobenzene-substituted polythiophenic copolymers were prepared by a regiospecific organometallic polycondensation procedure based on a Grignard metathesis reaction. Copolymers with a high content of chromophoric groups in the side chains and a high degree of configurational order of the backbones were obtained. A sample was also functionalized with hydroxyalkyl chains capable of setting up ordered supramolecular structures through hydrogen bonds. The final materials were fully characterized via NMR, IR, elemental analysis, GPC, DSC and X-ray diffraction. Moreover, measurements of NLO activity on polymer films showed the synthetic strategies adopted and monomers used to be correct. Values obtained by the in situ deprotection of the interacting functional groups after the alignment of the chromophorized side chains were very promising, proving the procedure to be suitable for industrial and commercial applications. 相似文献
87.
Jrmy Lamarche Luisa Ronga Joanna Szpunar Ryszard Lobinski 《International journal of molecular sciences》2021,22(12)
Selenoprotein P (SELENOP) is an emerging marker of the nutritional status of selenium and of various diseases, however, its chemical characteristics still need to be investigated and methods for its accurate quantitation improved. SELENOP is unique among selenoproteins, as it contains multiple genetically encoded SeCys residues, whereas all the other characterized selenoproteins contain just one. SELENOP occurs in the form of multiple isoforms, truncated species and post-translationally modified variants which are relatively poorly characterized. The accurate quantification of SELENOP is contingent on the availability of specific primary standards and reference methods. Before recombinant SELENOP becomes available to be used as a primary standard, careful investigation of the characteristics of the SELENOP measured by electrospray MS and strict control of the recoveries at the various steps of the analytical procedures are strongly recommended. This review critically discusses the state-of-the-art of analytical approaches to the characterization and quantification of SELENOP. While immunoassays remain the standard for the determination of human and animal health status, because of their speed and simplicity, mass spectrometry techniques offer many attractive and complementary features that are highlighted and critically evaluated. 相似文献
88.
89.
Hydrometallurgical separation of aluminium,cobalt, copper and lithium from spent Li-ion batteries 总被引:1,自引:0,他引:1
Daniel Alvarenga Ferreira Luisa Martins Zimmer PradosDaniel Majuste Marcelo Borges Mansur 《Journal of power sources》2009
A hydrometallurgical route based on leaching-crystallization steps for the separation of metals Al, Co, Cu and Li from spent Li-ion batteries was evaluated in this paper. Once dismantled for the removal of both plastic and steel cases, the anode (containing mainly Cu) of such batteries was manually separated from the cathode (which contains Al, Co and Li) for the recovery of Cu. The metal content of both anode and cathode was assessed by X-ray diffraction (XRD), X-ray fluorescence (XRF) and atomic absorption analytical methods. The cathode was firstly leached with NaOH for the selective removal of Al, followed by leaching with H2SO4 + H2O2 for the dissolution of the remaining Co and Li. The operating variables concentration of NaOH and concentration of H2O2 were found significant for the metal dissolution conditions investigated at basic and acid leaching operations, respectively. On the other hand, the variables temperature and concentration of H2SO4 showed minor effects at acid leaching step. Reaction schemes were proposed to describe basic and acid leaching operations. The recovery of Co from the acid liquor was carried out by crystallization. This hydrometallurgical route was found to be simple and adequate to separate metals for recycling purposes. 相似文献