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1.
Fabiana Quaglia Giuseppe Fusco Giuseppe De Rosa Francesca Ungaro Agnese Miro Maria Immacolata La Rotonda 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):669-674
The aim of this work was to produce lycopene-containing powders from tomato products by a solvent-free method making use of
β-cyclodextrin (βCD). Powders were prepared by spray-drying a tomato concentrate (TC), one of the most bioavailable form of
lycopene, after mechanical treatment with βCD in different weight ratios. The obtained product was centrifuged to eliminate
partly food matrix and characterized for the amount of lycopene hydrodispersed/hydrosolubilized in the aqueous fraction. The
chemical antioxidant activity of sera was evaluated too. Powders obtained by spray-drying sera exhibited good flow properties,
a lycopene content between 0.4 and 1.09 mg/g and excellent water dispersability. The process developed, which makes use of
βCD for the treatment of tomato products, turns to be of great interest to obtain a bulk material for nutraceuticals displaying
superior biovailability of lycopene. 相似文献
2.
Christoph Meingast Frank Gugenberger Georg Roth Miro Haluška Hans Kuzmany 《Zeitschrift für Physik B Condensed Matter》1994,95(1):67-71
The thermal expansion of vapor-grownC
70 single crystals ahs been investigated using high-resolution capacitance dilatometry from 5–380 K. Measurements were made both parallel and perpendicular to the hexagonalc-axis. Three first-order phase transitions which we associate with the consecutive disordering of theC
70 molecules are observed upon heating at 280 K (long-axis spinning), 300 K (long-axis precession) and 355 K (quasi-free rotation), respectively. The highest-temperature transition exhibits a very large (50 K) thermal hysteresis. Powder and single-crystal X-ray diffraction show that the crystals are predominantly hexagonal-close-packed (HCP) with an idealc/a1.63 above 360 K andc/a1.84 at 295 K. 相似文献
3.
This article describes the structure determination of five homoleptic d(10) metal-aryl/alkylacetylides [RC triple bond CM] (M=Cu, R=tBu 1, nPr 2, Ph 3; R=Ph, M=Ag 4; Au 5) by using X-ray single-crystal and powder diffraction. Complex 1.C6H6 reveals an unusual Cu20 catenane cluster structure that has various types of tBuC triple bond C-->Cu coordination modes. By using this single-crystal structure as a starting model for subsequent Rietveld refinement of X-ray powder diffraction data, the structure of the powder synthesized from CuI and tBuC triple bond CH was found to have the same structure as 1. Complex 2 has an extended sheet structure consisting of discrete zig-zag Cu4 subunits connected through bridging nPrC triple bond C groups. Complex 3 forms an infinite chain structure with extended Cu-Cu ladders (Cu-Cu=2.49(4)-2.83(2) A). The silver(I) congener 4 is iso-structural to 3 (average Ag-Ag distance 3.11 A), whereas the gold(I) analogue 5 forms a Au...Au honeycomb network with PhC triple bond C pillars (Au-Au=2.98(1)-3.26(1) A). Solid-state properties including photoluminescence, nu(C triple bond C) stretching frequencies and thermal stability of these polymeric systems are discussed in the context of the determined structures. 相似文献
4.
Md. Nur Alam Miro Antal Alvaro Tejado Theo G. M. van de Ven 《Cellulose (London, England)》2012,19(2):517-522
Chemical reactions in charged nanopores, such as present in cellulose fibers, can be accelerated by adding an inert salt,
that does not participate in the reaction. Due to a Donnan-like equilibrium between ions inside and outside the pores, the
concentration of co-ions in the nanopores (having a charge of the same sign as that of the pore wall), is lower than the concentration
in the bulk. The co-ion concentration in pores can be increased by adding an inert salt, which shifts the Donnan equilibrium.
The increased concentration of reactants in pores results in faster reaction kinetics. Reactions of cellulose with periodate
confirm these predictions. 相似文献
5.
Paula Miro Virginie Lhiaubet‐Vallet M. Luisa Marin Miguel A. Miranda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):17051-17056
A new mechanism of photosensitized formation of thymine (Thy) dimers is proposed, which involves generation of a delocalized triplet excited state as the key step. This is supported by chemical evidence obtained by combining one benzophenone and two Thy units with different degrees of freedom, whereby the photoreactivity is switched from a clean Paternò–Büchi reaction to a fully chemo‐, regio‐, and stereoselective [2+2] cycloaddition. 相似文献
6.
Quantitative assessment of the enzymatic degradation of amorphous cellulose by using a quartz crystal microbalance with dissipation monitoring 总被引:1,自引:0,他引:1
Suchy M Linder MB Tammelin T Campbell JM Vuorinen T Kontturi E 《Langmuir : the ACS journal of surfaces and colloids》2011,27(14):8819-8828
The systematic evaluation of the degradation of an amorphous cellulose film by a monocomponent endoglucanase (EG I) by using a quartz crystal microbalance with dissipation monitoring (QCM-D) identified several important aspects relevant to the study the kinetics of cellulose degradation by enzymes. It was demonstrated that, to properly evaluate the mechanism of action, steady state conditions in the experimental set up need to be reached. Rinsing or diluting the enzyme, as well as concentration of the enzyme, can have a pronounced effect on the hydrolysis. Quantification of the actual hydrolysis was carried out by measuring the film thickness reduction by atomic force microscopy after the enzymatic treatment. The values correlated well with the frequency data obtained by QCM-D measurement for corresponding films. This demonstrated that the evaluation of hydrolysis by QCM-D can be done quantitatively. Tuning of the initial thickness of films enabled variation of the volume of substrate available for hydrolysis which was then utilized in establishing a correlation between substrate volume and hydrolytic activity of EG I as measured by QCM-D. It was shown that, although the amount of substrate affects the absolute rate of hydrolysis, the relative rate of hydrolysis does not depend on the initial amount of substrate in steady state system. With this experimental setup it was also possible to demonstrate the impact of concentration on crowding of enzyme and subsequent hydrolysis efficiency. This effort also shows the action of EG I on a fully amorphous substrate as observed by QCM-D. The enzyme was shown to work uniformly within the whole volume of swollen film, however being unable to fully degrade the amorphous film. 相似文献
7.
F. Delmas V. Trocheris C. Miro J. C. Murat I. Villaescusa 《Fresenius' Journal of Analytical Chemistry》1996,354(5-6):615-619
Human cell lines cultured under standardized conditions are found to react after a wide variety of aggressive but sub-lethal treatments by expressing stress proteins, mainly of the HSP68, HSP70 and HSP90 families. The stress reaction is a repair mechanism which rapidly takes place after minute damages caused to cell structures. It was therefore proposed to develop a sensitive biomarker to monitor environmental pollution, especially related to metals, based on the evaluation of stress protein production. This was achieved by computer-assisted densitometric analysis of autoradiographies of electrophoretically separated 35S-labelled proteins. The results indicate that our biological models consisting in HT29 and HepG2 cell-lines react to low concentrations of cadmium or nickel by a clear-cut increase of stress proteins expression. In most cases, this effect is much more significant and much more rapid to observe than changes in growth curves. It may constitute a reliable index of cell susceptibility to environmental aggressions. 相似文献
8.
Chaohuang Chen Philipp Miro Pflüger Pinhong Chen Guosheng Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2414-2418
Asymmetric PdII‐catalyzed intramolecular aminotrifluoromethoxylation of unactivated alkenes using readily accessible and stable CsOCF3 as a trifluoromethoxide source has been developed, which affords a wide variety of enantiomerically enriched β‐substituted OCF3‐containing piperidines in good yields. Introducing a sterically bulky group into pyridine‐oxazoline (Pyox) ligands is crucial to increasing both reactivity and enantioselectivity for the reaction. Additionally, the reaction features good functional group compatibility and mild reaction conditions. 相似文献
9.
A Study of Student Engagement in Project‐Based Learning Across Multiple Approaches to STEM Education Programs
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Objective: In this study, we investigated the implementation of project‐based learning (PBL) activities in four secondary science, technology, engineering, and mathematics (STEM) education settings to examine the impact of inquiry based instructional practices on student learning. Method: Direct classroom observations were conducted during the 2013–2014 school year in STEM Traditional Courses, a STEM Platform School, an Engineering Optional Program (EOP), and a Virtual STEM Academy (VSA) to measure teacher instructional practices (School Observation Measure) and student engagement (The Rubric for Student‐Centered Activities). Results: The four approaches to STEM education showed significant differences in their implementation of PBL, with the EOP and VSA having higher incidences of PBL activities. Additionally, higher‐level questioning strategies, higher‐order instructional feedback, and integration of STEM subject areas was absent or rarely observed. Conclusions: Components of PBL are missing in STEM education, in traditional and non‐traditional STEM courses. In‐service teachers may benefit from professional development that enhances their understanding of PBL activities to maximize student learning opportunities. 相似文献
10.
Ljubicić D Stipcević T Pivac N Jakovljević M Mück-Seler D 《Journal of photochemistry and photobiology. B, Biology》2007,89(2-3):63-69
Platelet serotonin (5-HT) can be used as a limited, peripheral model for the central 5-HT synaptosomes. Altered platelet 5-HT concentrations have been associated with psychiatric disorders like depression and schizophrenia. The aim of the present study was to compare platelet 5-HT concentrations during long, medium and short period of natural daylight exposure in a large number of medication-free male and female schizophrenic and depressed patients and sex-matched healthy controls. Platelet 5-HT concentration was determined spectrofluorimetrically in 240 (97 female, 143 male) schizophrenic and 258 (153 female, 105 male) nonpsychotic, nonsuicidal depressed medication-free patients and 328 (149 women, 179 men) healthy subjects during periods with short (<12), long (>12) and medium (average 12) hours of the natural daylight. Platelet 5-HT concentration was significantly lower in women compared to men in all groups. Healthy male subjects had significantly higher (p=0.011) platelet 5-HT concentrations during long compared to medium period. There were no significant differences (p>0.05) in platelet 5-HT concentration between different periods in healthy women. The significant increase in platelet 5-HT values were found in female (p=0.01) and male (p=0.029) depressed patients during long compared to short period. There were no significant associations between platelet 5-HT concentrations and different periods in both male and female schizophrenic patients. The results indicate the sex-related differences in the serotonergic system. The alterations of platelet 5-HT concentrations, observed across period with different durations of daylight exposure, point to a direct or indirect effect of light on peripheral 5-HT system that could be related to different sensitivity of the pineal gland to light and/or melatonin influence on 5-HT metabolism. 相似文献