908 research outputs found
Identifications of polyphenols and quantification of anthocyanidins in grapes and grape-derived products
No full textPolyphenols in grapes and grape-derived products have attracted public and scientific attention due to their numerous protective roles to human health. A rapid and comprehensive qualitative method was developed to characterize the different classes of polyphenols, such as anthocyanins, flavonols, phenolic acids and flavanols/proanthocyanidins, in grapes and grape-derived products. The detection was achieved by two runs with same HPLC gradient in different MS ionization modes and mobile phase modifiers (positive mode and 0.4% trifluoroacetic acid for anthocyanins and flavonols, negative mode and 0.1% formic acid for phenolic acids and flavanols). Under the optimized LC/MS conditions and based on the analysis of the MS and UV data and in comparison with the authenticated standards, a total of 53 polyphenolic compounds were successfully separated and individually identified including 33 anthocyanins, 12 flavonols, 4 phenolic acids and 4 flavanols/proanthocyanidins. With the method developed, a survey was conducted to qualitatively assess and compare the composition of polyphenols among 29 grapes and grape-derived products. To facilitate the quantitation of the major class of polyphenolic anthocyanidins, a simple and precise acid assisted hydrolysis method was established for the quantitation of anthocyanidins in grape juice samples, grape berries and grape skins using LC/MS. Five most common anthocyanidins of delphenidin, petunidin, cyanidin, malvidin, and peonidin in the hydrolyzed grape extracts were included in the quantification study. The validation of this method showed that the recovery percentages of five anthocyanidins ranged from 98.59 % to 103.20% with the relative standard deviation (RSD) less than 5.03%. The qualitative method provided complete insight into the composition of polyphenols in grapes, and other grape-derived products. This quantitative method provides a rapid and accurate tool to quantitatively study individual anthocyanidin in grapes or grape juice samples for quality control and to facilitate the evaluation and comparison of new commercial grapes or grape juice products in market.M.S.Includes bibliographical referencesby Yanping X
Impairment of hypoxia-induced angiogenesis by LDL involves a HIF-centered signaling network linking inflammatory TNFα and angiogenic VEGF
No full textMultiscale asymptotic method for Steklov eigenvalue equations in composite media
No full textAuthor name used in this publication: Yanping Lin2012-2013 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedVoR allowe
Developing finite element methods for maxwell's equations in a cole-cole dispersive medium
No full textAuthor name used in this publication: Yanping Lin2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedVoR allowe
Multiscale asymptotic method for Maxwell's equations in composite materials
No full textAuthor name used in this publication: Yanping Lin2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedVoR allowe
The Harrod-Balassa-Samuelson Hypothesis: Real Exchange Rates and their Long-Run Equilibrium
Get PDFFrictionless, perfectly competitive traded-goods markets justify thinking of purchasing power parity (PPP) as the main driver of exchange rates in the long-run. But differences in the traded/non-traded sectors of economies tend to be persistent and affect movements in local price levels in ways that upset the PPP balance (the underpinning of the Harrod-Balassa-Samuelson hypothesis, HBS). This paper uses panel-data techniques on a broad collection of countries to investigate the long-run properties of the PPP/HBS equilibrium using novel local projection methods for cointegrated systems. These semi-parametric methods isolate the long-run behavior of the data from contaminating factors such as frictions not explicitly modelled and thought to have effects only in the short-run. Absent the short-run effects, we find that the estimated speed of reversion to long-run equilibrium is much higher. In addition, the HBS effects means that the real exchange rate is converging not to a steady mean, but to a slowly to a moving target. The common failure to properly model this effect also biases the estimated speed of reversion downwards. Thus, the so-called "PPP puzzle" is not as bad as we thought.
The evolution of the Han wedding dress design research and innovation / Gu Yanping and Rose Dahlina Rusli
Get PDFChina's long history has given birth to a colorful folk culture, and weddings are a significant part of life. The Chinese often use the term "married" to describe one's marital status, and wedding attire plays a crucial role in this cultural expression. Particularly in China’s dominant ethnic group, the Han, wedding dress traditions are something people pay great attention to. This article explores the evolution of Han wedding attire, detailing how it has changed since the Zhou Dynasty, up through the reforms and opening to the outside world. Throughout the dynasties, Han wedding dresses have exhibited unique characteristics and differences. With the economic, political, and cultural developments during the early Republic era, the grand and solemn traditional wedding dress gradually became westernized. However, Han Chinese traditional wedding attire remains a living cultural symbol, embodying the unique, beautiful, and mysterious essence of ancient Oriental culture, and representing the Han nationality. In designing modern Han wedding dresses, it is important to create designs that are aligned with contemporary trends while preserving the distinct characteristics of Han culture. By incorporating elements from different dynasties, such as traditional patterns, colors, fabrics, and shapes, alongside modern techniques and some western influences, innovation in Han wedding dress design can be achieved. Furthermore, through combining this research with personal innovation design practices, we can continue to inherit and carry forward the tradition of Han wedding attire, making a lasting contribution to its preservation
Long-Range Hot Charge Transfer Exciton Dissociation in an Organic/2D Semiconductor Hybrid Excitonic Heterostructure
No full textWhether and how an electron–hole pair at the donor–acceptor
interface separates from their mutual Coulombic interaction has been
a long-standing question for both fundamental interests and optoelectronic
applications. This question is particularly interesting but yet to
be unraveled in the emerging mixed-dimensional organic/2D semiconductor
excitonic heterostructures where the Coulomb interaction is poorly
screened. Here, by tracking the characteristic electroabsorption (Stark
effect) signal from separated charges using transient absorption spectroscopy,
we directly follow the electron–hole pair separation process
in a model organic/2D heterostructure, vanadium oxide phthalocyanine/monolayer
MoS2. After sub-100 fs photoinduced interfacial electron
transfer, we observe a barrier-less long-range electron–hole
pair separation to free carriers within 1 ps by hot charge transfer
exciton dissociation. Further experiment reveals the key role of the
charge delocalization in organic layers sustained by the local crystallinity,
while the inherent in-plane delocalization of the 2D semiconductor
has a negligible contribution to charge pair separation. This study
reconciles the seemingly contradicting charge transfer exciton emission
and dissociation process and is important to the future development
of efficient organic/2D semiconductor optoelectronic devices
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