Porphyrin-sensitized solar cells with cobalt (II/III)-based redox electrolyte exceed 12 percent efficiency     

Yella A  Lee HW  Tsao HN  Yi C  Chandiran AK  Nazeeruddin MK  Diau EW  Yeh CY  Zakeeruddin SM  Grätzel M 《Science (New York, N.Y.)》2011,334(6056):629-634

The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co((II/III))tris(bipyridyl)-based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency of 12.3% under simulated air mass 1.5 global sunlight.  相似文献   

hamlet,a binary genetic switch between single- and multiple- dendrite neuron morphology     

Moore AW  Jan LY  Jan YN 《Science (New York, N.Y.)》2002,297(5585):1355-1358

The dendritic morphology of neurons determines the number and type of inputs they receive. In the Drosophila peripheral nervous system (PNS), the external sensory (ES) neurons have a single nonbranched dendrite, whereas the lineally related multidendritic (MD) neurons have extensively branched dendritic arbors. We report that hamlet is a binary genetic switch between these contrasting morphological types. In hamlet mutants, ES neurons are converted to an MD fate, whereas ectopic hamlet expression in MD precursors results in transformation of MD neurons into ES neurons. Moreover, hamlet expression induced in MD neurons undergoing dendrite outgrowth drastically reduces arbor branching.  相似文献   

Induction of phenolsulfotransferase expression by phenolic acids in human hepatoma HepG2 cells     

Yeh CT  Huang SM  Yen GC 《Journal of agricultural and food chemistry》2005,53(12):4766-4773

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Chemical compositions and physicochemical properties of the fiber-rich materials prepared from shoyu mash residue     

Yeh HY  Su NW  Lee MH 《Journal of agricultural and food chemistry》2005,53(11):4361-4366

Fiber-rich materials including desalted shoyu mash residue (briefly referred as desalted mash residue, DMR), alcohol-insoluble solid (AIS), and water-insoluble solid (WIS) were prepared from shoyu mash residue, which is a filtration cake obtained during the isolation of shoyu by press filtration of fermented matrix in the final process. The DMR, AIS, and WIS contain rich dietary fiber of 52.4, 61.5, and 54.7 wt %, respectively. The DMR, AIS, and WIS all have significantly lower bulk densities, and higher water-holding capacities, oil-holding capacities, swelling abilities, and cation-exchange capacities than the control cellulose. These results indicated that the said fiber-rich materials prepared in this study all have the desired physicochemical properties for being used as satisfactory sources of dietary fibers or low-calorie bulk ingredients in food applications requiring oil and moisture retention. Furthermore, the said fiber-rich materials also have high contents of isoflavones, mainly daidzein and genistein, which are considered as the most bioavailable phytoestrogens, with a total amount of about 1200-1480 micromol/100 g (equal to daidzein of ca. 3040-3759 microg/g, or genistein of 3240-3996 microg/g). The results revealed that the said fiber-rich materials might be a potent fiber source for health foods.  相似文献   

Induction of apoptosis by the Anthocyanidins through regulation of Bcl-2 gene and activation of c-Jun N-terminal kinase cascade in hepatoma cells   总被引：3，自引：0，他引：3  

Yeh CT  Yen GC 《Journal of agricultural and food chemistry》2005,53(5):1740-1749

Anthocyanidins that are reddish pigments widely distributed in fruit and vegetables have been reported to possess antioxidant and anticancer activities. To understand the molecular basis of the putative anticancer activity of anthocyanidins, we investigated the antiproliferation effects of anthocyanidins in human hepatoma cell lines. Delphinidin, cyanidin, and malvidin exhibited strong growth inhibitory effects against human hepatoma HepG(2), but were less effective against Hep3B. According to the appearance of the caspase-3 fragments and stimulated proteolytic cleavage of poly (ADP-ribose) polymerase (PARP) in time-dependent studies, delphinidin induced apoptotic cell death characterized by internucleosomal DNA fragmentation and caused a rapid induction of caspase-3 activity. RT-PCR and Western blot data revealed that delphinidin stimulated an increase in the c-Jun and JNK phosphorylation expression at mRNA and protein levels, respectively. Moreover, delphinidin-induced apoptotic cell death was accompanied by up-regulation of Bax and down-regulation of Bcl-2 protein. Dephinidin-induced DNA fragmentation was blocked by N-acetyl-l-cysteine and catalase, suggesting that the death signaling was triggered by oxidative stress. Our experiments provide evidence that delphinidin is an effective apoptosis inducer in HepG(2) cells through regulation of Bcl-2 family moleculars and activation of c-Jun N-terminal kinase cascade. The results suggest that induction of apoptosis by anthocyanidins is a pivotal mechanism of their cancer chemopreventive functions.  相似文献   

Effects of phenolic acids on human phenolsulfotransferases in relation to their antioxidant activity     

Yeh CT  Yen GC 《Journal of agricultural and food chemistry》2003,51(5):1474-1479

Sulfate conjugation by phenolsulfotransferase (PST) enzyme is an important process in the detoxification of xenobiotics and endogenous compounds. There are two forms of PST that are specific for the sulfation of small phenols (PST-P) and monoamines (PST-M). Phenoilc acids have been reported to have important biological and pharmacological properties and may have benefits to human health. In the present study, human platelets were used as a model to investigate the influence of 13 phenolic acids on human PST activity and to evaluate the relationship to their antioxidant activity. The results showed that chlorogenic acid, syringic acid, protocatechuic acid, vanillic acid, sinapic acid, and caffeic acid significantly (p < 0.05) inhibited the activities of both forms of PST by 21-30% at a concentration of 6.7 microM. The activity of PST-P was enhanced (p < 0.05) by p-hydroxybenzoic acid, gallic acid, gentisic acid, o-coumaric acid, p-coumaric acid, and m-coumaric acid at a concentration of 6.7 microM, whereas the activity of PST-M was enhanced by gentisic acid, gallic acid, p-hydroxybenzoic acid, and ferulic acid. The phenolic acids exhibited antioxidant activity as determined by the oxygen radical absorbance capacity (ORAC) assay and Trolox equivalent antioxidant capacity (TEAC) assay, especially gallic acid, p-hydroxybenzoic acid, gentisic acid, and coumaric acid, which had strong activity. The overall effect of phenolic acids tested on the activity of PST-P and PST-M was well correlated to their antioxidant activity of ORAC value (r = 0.71, p < 0.01; and r = 0.66, p < 0.01). These observations suggest that antioxidant phenolic acids might alter sulfate conjugation.  相似文献   

Rapid screening of wood chemical component variations using transmittance near-infrared spectroscopy     

Yeh TF  Yamada T  Capanema E  Chang HM  Chiang V  Kadla JF 《Journal of agricultural and food chemistry》2005,53(9):3328-3332

A rapid transmittance near-infrared (NIR) spectroscopy method was developed to predict the variation in chemical composition of solid wood. The effect of sample preparation, sample quantity (single versus stacked multiple wood wafers), and NIR acquisition time on the quantification of alpha-cellulose and lignin content was investigated. Strong correlations were obtained between laboratory wet chemistry values and the NIR-predicted values. In addition to the experimental protocol and method development, improvements in calibration error associated with utilizing stacked multiple wood wafers as opposed to single wood wafers are also discussed.  相似文献   

Molecular cloning and expression of channel catfish, Ictalurus punctatus, complement membrane attack complex inhibitor CD59     

Yeh HY  Klesius PH 《Veterinary immunology and immunopathology》2007,120(3-4):246-253

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Ultrafast electron localization dynamics following photo-induced charge transfer     

Yeh AT  Shank CV  McCusker JK 《Science (New York, N.Y.)》2000,289(5481):935-938

Molecular dynamics occurring in the earliest stages following photo-induced charge transfer were investigated. Femtosecond time-resolved absorption anisotropy measurements on [Ru(bpy)(3)](2+), where bpy is 2,2'-bipyridine, reveal a time dependence in nitrile solutions attributed to initial delocalization of the excited state over all three ligands followed by charge localization onto a single ligand. The localization process is proposed to be coupled to nondiffusive solvation dynamics. In contrast, measurements sampling population dynamics show spectral evolution associated with wave packet motion on the excited state surface that is independent of solvent. The results therefore reveal two important contributions to the evolution of charge transfer states in condensed phase, one that is strongly coupled to the surrounding environment and another that follows a potential internal to the molecule.  相似文献   

Role of phycoerythrin in marine picoplankton Synechococcus spp   总被引：2，自引：0，他引：2  

S W Yeh  L J Ong  A N Glazer 《Science (New York, N.Y.)》1986,234(4782):1422-1424

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