Effect of heat treatment on the antioxidant activity of extracts from citrus peels   总被引：1，自引：0，他引：1  

Jeong SM  Kim SY  Kim DR  Jo SC  Nam KC  Ahn DU  Lee SC 《Journal of agricultural and food chemistry》2004,52(11):3389-3393

The effect of heat treatment on the antioxidant activity of extracts from Citrus unshiu peels was evaluated. Citrus peels (CP) (5 g) were placed in Pyrex Petri dishes (8.0 cm diameter) and heat-treated at 50, 100, or 150 degrees C for 10, 20, 30, 40, 50, and 60 min in an electric muffle furnace. After heat treatment, 70% ethanol extract (EE) and water extract (WE) (0.1 g/10 mL) of CP were prepared, and total phenol contents (TPC), radical scavenging activity (RSA), and reducing power of the extracts were determined. The antioxidant activities of CP extracts increased as heating temperature increased. For example, heat treatment of CP at 150 degrees C for 60 min increased the TPC, RSA, and reducing power of EE from 71.8 to 171.0 microM, from 29.64 to 64.25%, and from 0.45 to 0.82, respectively, compared to non-heat-treated control. In the case of WE from CP heat-treated at the same conditions (150 degrees C for 60 min), the TPC, RSA, and reducing power also increased from 84.4 to 204.9 microM, from 15.81 to 58.26%, and from 0.27 to 0.96, respectively. Several low molecular weight phenolic compounds such as 2,3-diacetyl-1-phenylnaphthalene, ferulic acid, p-hydroxybenzaldoxime, 5-hydroxyvaleric acid, 2,3-diacetyl-1-phenylnaphthalene, and vanillic acid were newly formed in the CP heated at 150 degrees C for 30 min. These results indicated that the antioxidant activity of CP extracts was significantly affected by heating temperature and duration of treatment on CP and that the heating process can be used as a tool for increasing the antioxidant activity of CP.  相似文献   

The mTOR-regulated phosphoproteome reveals a mechanism of mTORC1-mediated inhibition of growth factor signaling   总被引：1，自引：0，他引：1  

Hsu PP  Kang SA  Rameseder J  Zhang Y  Ottina KA  Lim D  Peterson TR  Choi Y  Gray NS  Yaffe MB  Marto JA  Sabatini DM 《Science (New York, N.Y.)》2011,332(6035):1317-1322

The mammalian target of rapamycin (mTOR) protein kinase is a master growth promoter that nucleates two complexes, mTORC1 and mTORC2. Despite the diverse processes controlled by mTOR, few substrates are known. We defined the mTOR-regulated phosphoproteome by quantitative mass spectrometry and characterized the primary sequence motif specificity of mTOR using positional scanning peptide libraries. We found that the phosphorylation response to insulin is largely mTOR dependent and that mTOR exhibits a unique preference for proline, hydrophobic, and aromatic residues at the +1 position. The adaptor protein Grb10 was identified as an mTORC1 substrate that mediates the inhibition of phosphoinositide 3-kinase typical of cells lacking tuberous sclerosis complex 2 (TSC2), a tumor suppressor and negative regulator of mTORC1. Our work clarifies how mTORC1 inhibits growth factor signaling and opens new areas of investigation in mTOR biology.  相似文献   

Two-dimensional nanosheets produced by liquid exfoliation of layered materials   总被引：1，自引：0，他引：1  

Coleman JN  Lotya M  O'Neill A  Bergin SD  King PJ  Khan U  Young K  Gaucher A  De S  Smith RJ  Shvets IV  Arora SK  Stanton G  Kim HY  Lee K  Kim GT  Duesberg GS  Hallam T  Boland JJ  Wang JJ  Donegan JF  Grunlan JC  Moriarty G  Shmeliov A  Nicholls RJ  Perkins JM  Grieveson EM  Theuwissen K  McComb DW  Nellist PD  Nicolosi V 《Science (New York, N.Y.)》2011,331(6017):568-571

If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS(2), WS(2), MoSe(2), MoTe(2), TaSe(2), NbSe(2), NiTe(2), BN, and Bi(2)Te(3) can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exfoliated into individual layers. By blending this material with suspensions of other nanomaterials or polymer solutions, we can prepare hybrid dispersions or composites, which can be cast into films. We show that WS(2) and MoS(2) effectively reinforce polymers, whereas WS(2)/carbon nanotube hybrid films have high conductivity, leading to promising thermoelectric properties.  相似文献   

Does Rydberg state manipulation equal quantum computation?     

Meyer DA  Kwiat PG  Hughes RJ  Bucksbaum PH  Ahn J  Weinacht TC 《Science (New York, N.Y.)》2000,289(5484):1431a

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Ultrafast flash thermal conductance of molecular chains     

Wang Z  Carter JA  Lagutchev A  Koh YK  Seong NH  Cahill DG  Dlott DD 《Science (New York, N.Y.)》2007,317(5839):787-790

At the level of individual molecules, familiar concepts of heat transport no longer apply. When large amounts of heat are transported through a molecule, a crucial process in molecular electronic devices, energy is carried by discrete molecular vibrational excitations. We studied heat transport through self-assembled monolayers of long-chain hydrocarbon molecules anchored to a gold substrate by ultrafast heating of the gold with a femtosecond laser pulse. When the heat reached the methyl groups at the chain ends, a nonlinear coherent vibrational spectroscopy technique detected the resulting thermally induced disorder. The flow of heat into the chains was limited by the interface conductance. The leading edge of the heat burst traveled ballistically along the chains at a velocity of 1 kilometer per second. The molecular conductance per chain was 50 picowatts per kelvin.  相似文献   

Evidence of a pluripotent human embryonic stem cell line derived from a cloned blastocyst     

Hwang WS  Ryu YJ  Park JH  Park ES  Lee EG  Koo JM  Jeon HY  Lee BC  Kang SK  Kim SJ  Ahn C  Hwang JH  Park KY  Cibelli JB  Moon SY 《Science (New York, N.Y.)》2004,303(5664):1669-1674

Somatic cell nuclear transfer (SCNT) technology has recently been used to generate animals with a common genetic composition. In this study, we report the derivation of a pluripotent embryonic stem (ES) cell line (SCNT-hES-1) from a cloned human blastocyst. The SCNT-hES-1 cells displayed typical ES cell morphology and cell surface markers and were capable of differentiating into embryoid bodies in vitro and of forming teratomas in vivo containing cell derivatives from all three embryonic germ layers in severe combined immunodeficient mice. After continuous proliferation for more than 70 passages, SCNT-hES-1 cells maintained normal karyotypes and were genetically identical to the somatic nuclear donor cells. Although we cannot completely exclude the possibility that the cells had a parthenogenetic origin, imprinting analyses support a SCNT origin of the derived human ES cells.  相似文献   

National character does not reflect mean personality trait levels in 49 cultures     

Terracciano A  Abdel-Khalek AM  Adám N  Adamovová L  Ahn CK  Ahn HN  Alansari BM  Alcalay L  Allik J  Angleitner A  Avia MD  Ayearst LE  Barbaranelli C  Beer A  Borg-Cunen MA  Bratko D  Brunner-Sciarra M  Budzinski L  Camart N  Dahourou D  De Fruyt F  de Lima MP  del Pilar GE  Diener E  Falzon R  Fernando K  Ficková E  Fischer R  Flores-Mendoza C  Ghayur MA  Gülgöz S  Hagberg B  Halberstadt J  Halim MS  Hrebícková M  Humrichouse J  Jensen HH  Jocic DD  Jónsson FH  Khoury B  Klinkosz W  Knezević G  Lauri MA  Leibovich N  Martin TA 《Science (New York, N.Y.)》2005,310(5745):96-100

Most people hold beliefs about personality characteristics typical of members of their own and others' cultures. These perceptions of national character may be generalizations from personal experience, stereotypes with a "kernel of truth," or inaccurate stereotypes. We obtained national character ratings of 3989 people from 49 cultures and compared them with the average personality scores of culture members assessed by observer ratings and self-reports. National character ratings were reliable but did not converge with assessed traits. Perceptions of national character thus appear to be unfounded stereotypes that may serve the function of maintaining a national identity.  相似文献   

Electrical resistance of long conjugated molecular wires     

Ho Choi S  Kim B  Frisbie CD 《Science (New York, N.Y.)》2008,320(5882):1482-1486

The charge transport mechanism of a wire can be revealed by how its electrical resistance varies with length. We have measured the resistance and current-voltage characteristics of conjugated molecular wires ranging in length from 1 to 7 nanometers, connected between metal electrodes. We observe the theoretically predicted change in direct-current transport from tunneling to hopping as a function of systematically controlled wire length. We also demonstrate that site-specific disruption of conjugation in the wires greatly increases resistance in the hopping regime but has only a small effect in the tunneling regime. These nanoscale transport measurements elucidate the role of molecular length and bond architecture on molecular conductivity and open opportunities for greater understanding of electrical transport in conjugated polymer films.  相似文献   

Occurrence of Honeysuckle Yellow Vein Virus (HYVV) containing a monopartite DNA-A genome in Korea     

Yuan Wang  Jing Ji  Tae-Kyun Oh  Sung Oh  Sue Hoon Kim  Hyun Ju Lee  Myoung Yong Shim  Chang Won Choi  Seong Hwan Kim  Il-Seop Kim  Young Shik Kim 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(3):361-370

Two newly emerged begomoviruses were isolated from naturally infected tomato (Solanum lycopersicum) plants grown in greenhouses at Jeju Island and Dangjin in Korea and their genomes were characterized. These viruses-infected plants had very small leaves that curled upward, yellow margins and a leathery appearance, and a bushy and stunted appearance with short internodes. Nucleotide (nt) sequence analysis of their genomes showed that they have a DNA-A component of a monopartite begomovirus. Their genomes comprised 2763 and 2764 nucleotides with six open reading frames. The results of nt sequence similarity analysis of DNA-A genome between the two Korean isolates and isolates of Tobacco leaf curl Japan virus (TbLCJV), Honeysuckle yellow vein virus (HYVV), Honeysuckle yellow vein mosaic virus (HYVMV), and Eupatorium yellow vein virus in Japan (EpYVV) showed that they are likely similar to HYVV-[Masuda] (89.4–92.8% nt identity). Consequently, we tentatively propose the two isolates’ names as HYVV-Jeju and -DJ according to the ICTV geminivirus rules. Phylogenetic relationship analysis of 33 DNA-A genome sequences using PAUP* 4.0b10 and MrBayes revealed that HYVV-Jeju and -DJ belong to the Far East Asian begomovirus species complex. Within the Far East Asian begomovirus species complex, HYVV-Jeju and -DJ are distantly related to EpYVV, HYVMV, and TbLCJV groups. Based on the presence of a recombination fragment spanning the C3 ORF, a recombinant origin was suggested for both HYVV-Jeju and –DJ, with parents close to Japanese isolates HYVMV-[SP1:00] and Eupatorium yellow vein virus (EpYVV)-[Suya]. In addition, the presence of a further recombination fragment spanning the IR suggested the parents of HYVV-DJ were close to HYVV-Jeju and EpYVV-[Suya].  相似文献   

Development of an enzyme-linked immunosorbent assay for the detection of the organophosphorus insecticide acephate   总被引：1，自引：0，他引：1  

Lee JK  Ahn KC  Stoutamire DW  Gee SJ  Hammock BD 《Journal of agricultural and food chemistry》2003,51(13):3695-3703

A competitive indirect enzyme-linked immunosorbent assay (ciELISA) for the organophosphorus insecticide acephate, O,S-dimethyl acetylphosphoramidothioate, was developed using a polyclonal antibody. Five different haptens mimicking the analyte were synthesized and conjugated with the carrier proteins bovine serum albumin (BSA) and keyhole limpet hemocyanin (KLH) by the N-hydroxysuccinimide active ester and diazotization methods. Polyclonal antibodies raised against hapten-KLH conjugates in rabbits and hapten-BSA conjugates as coating antigens were screened and selected for the assay in the homologous and heterologous ELISA systems. The effects of various assay conditions such as detergent, organic solvents, pH, and preincubation of the mixture of the polyclonal antibody and the analyte on the sensitivity were evaluated. The IC(50) value for acephate was 25 ng/mL in an optimized heterologous system using hapten-4-BSA as a coating antigen and a polyclonal antibody no. 8377 against hapten-1-KLH, showing the detection range of 5-140 ng/mL and the lowest detection limit of 2 ng/mL. The cross-reactivities of the structurally related organophosphorus insecticides, including the major metabolite of the analyte, methamidophos, were less than 1%. Recoveries from the analyte-fortified tap water, mulberry leaves, and lettuce samples in the assay were in the range of 72-121% by simple extraction, concentration, and dilution. These results indicate that the ELISA could be a convenient and supplemental analytical tool for monitoring acephate residues in environmental and agricultural samples.  相似文献