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61.
Lucian BaiaRazvan Stefan Wolfgang Kiefer Jürgen PoppSimion Simon 《Journal of Non》2002,303(3):379-386
Raman and infrared spectroscopy have been employed to investigate the 99.5%[xB2O3(1−x)Bi2O3]0.5%CuO glasses with different Bi/B nominal ratios (0.07?x?0.625) in order to obtain information about the competitive role of B2O3 and Bi2O3 in the formation of the glass network. The glass samples have been prepared by melting at 1100 °C and rapidly cooling at room temperature. In order to relax the structure, to improve the local order and to develop crystalline phases the glass samples were kept at 575 °C for 10 h. The influence of both Bi2O3 and CuO on the vitreous B2O3 network as well as the local order changes around bismuth and boron atoms in as prepared and heat treated samples was studied. Structural modifications occurring in heat treated samples compared to the untreated glasses have been observed. 相似文献
62.
Heba A. S. El-Nashar Mariam I. Gamal El-Din Lucian Hritcu Omayma A. Eldahshan 《Molecules (Basel, Switzerland)》2021,26(24)
Tyrosinase is a multifunctional copper-containing oxidase enzyme that initiates melanin synthesis in humans. Excessive accumulation of melanin pigments or the overexpression of tyrosinase may result in skin-related disorders such as aging spots, wrinkles, melasma, freckles, lentigo, ephelides, nevus, browning and melanoma. Nature expresses itself through the plants as a source of phytochemicals with diverse biological properties. Among these bioactive compounds, flavonoids represent a huge natural class with different categories such as flavones, flavonols, isoflavones, flavan-3-ols, flavanones and chalcones that display antioxidant and tyrosinase inhibitor activities with a diversity of mechanistic approaches. In this review, we explore the role of novel or known flavonoids isolated from different plant species and their participation as tyrosinase inhibitors reported in the last five years from 2016 to 2021. We also discuss the mechanistic approaches through the different studies carried out on these compounds, including in vitro, in vivo and in silico computational research. Information was obtained from Google Scholar, PubMed, and Science Direct. We hope that the updated comprehensive data presented in this review will help researchers to develop new safe, efficacious, and effective drug or skin care products for the prevention of and/or protection against skin-aging disorders. 相似文献
63.
Lucian Gabriel Bahrin Alina Nicolescu Sergiu Shova Narcisa Laura Marangoci Lucian Mihail Birsa Laura Gabriela Sarbu 《Molecules (Basel, Switzerland)》2021,26(19)
Mesitylene was used as a core in seven new tritopic nitrogen containing linkers. Three of the linkers, each containing three nitrile groups, were obtained through Suzuki, Sonogashira and Heck-type coupling reactions. Next, these were converted to tetrazol-5-yl moieties by the cycloaddition of sodium azide to the nitrile functionalities. The last linker, containing three 1,2,3-triazol-4-yl moieties, was synthesized by the Huisgen cycloaddition of phenyl azide to the corresponding alkyne. The latter was obtained via a Corey–Fuchs reaction sequence from the previously reported formyl derivative. As the proof of concept for their potential in MOF design, one of the nitriles was used to build an Ag-based network. 相似文献
64.
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66.
This paper investigates the tightness property of the capacityinduced by the reduction operator with respect to the resolventof a right Markov process. Tightness is verified in two particularsituations: under the weak duality hypothesis,and if a substitute for the axiom of polarity for thedual theory holds. In the second context, the quasi-continuityproperty for the excessive functions is derived. These are extensionsand improvements of results of Lyons and Röckner, Ma andRöckner, Le Jan, and Fitzsimmons, mainly obtained in thecontext of Dirichlet forms. 2000 Mathematics Subject Classification31C25, 60J45 (primary), 31C15, 60J40 (secondary). 相似文献
67.
Kontsevich’s formality theorem and the consequent star-product formula rely on the construction of an L
∞-morphism between the DGLA of polyvector fields and the DGLA of polydifferential operators. This construction uses a version
of graphical calculus. In this article we present the details of this graphical calculus with emphasis on its algebraic features.
It is a morphism of differential graded Lie algebras between the Kontsevich DGLA of admissible graphs and the Chevalley–Eilenberg
DGLA of linear homomorphisms between polyvector fields and polydifferential operators. Kontsevich’s proof of the formality
morphism is reexamined in this light and an algebraic framework for discussing the tree-level reduction of Kontsevich’s star-product
is described.
Mathematics Subject Classifications (2000): 53D55, secondary 18G55 相似文献
68.
Suppose that U is the resolvent of a Borel right process on a Lusin space X. If is a U-excessive measure on X then we show by analytical methods that for every U-excessive measure with the Radon–Nikodym derivative d/d possesses a finely continuous version. (Fitzsimmons and Fitzsimmons and Getoor gave a probabilistic approach for this result.) We extend essentially a technique initiated by Mokobodzki and deepened by Feyel. The result allows us to establish a Revuz type formula involving the fine versions, and to study the Revuz correspondence between the -finite measures charging no set that is both -polar and -negligible (U being the potential component of ) and the strongly supermedian kernels on X. This is an analytic version of a result of Azéma, Fitzsimmons and Dellacherie, Maisonneuve and Meyer, in terms of additive functionals or homogeneous random measures. Finally we give an application to the context of the semi-Dirichlet forms, covering a recent result of Fitzsimmons. 相似文献
69.
We consider a proper submarkovian resolvent of kernels on a Lusin measurable space and a given excessive measure ξ. With
every quasi bounded excessive function we associate an excessive kernel and the corresponding Revuz measure. Every finite
measure charging no ξ–polar set is such a Revuz measure, provided the hypothesis (B) of Hunt holds. Under a weak duality hypothesis,
we prove the Revuz formula and characterize the quasi boundedness and the regularity in terms of Revuz measures. We improve
results of Azéma [2] and Getoor and Sharpe [20] for the natural additive functionals of a Borel right process.
Received: 30 April 1997 / Revised version: 17 September 1999 /?Published online: 11 April 2000 相似文献