oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Carotenoids
Abdel Nasser B. Singab,Omayma A. Eldahshan
Journal of Pharmacognosy and Phytochemistry , 2013,
Abstract: Carotenoids form one of the most important classes of plant pigments and play a crucial role in defining the quality parameters of fruit and vegetables. Carotenoids are of great interest due to their essential biological functions in both plants and animals. Herein, the review article discuss how carotenoids synthesised in plants leading to different types, their role in plants and biological activities to human and all details concerning the most important carotenoids in our life.
Characterization of solution processed TiOx buffer layers in inverted organic photovoltaics by XPS and DFT studies  [PDF]
Ivan S. Zhidkov,Ernst Z. Kurmaev,Michel A. Korotin,Andrey I. Kukharenko,Achilleas Savva,Stelios A. Choulis,Danila M. Korotin,Seif O. Cholakh
Physics , 2014,
Abstract: We present the results of XPS measurements (core levels and valence bands) of solution processed TiOx thin films prepared from titanium butoxide (C16H36O4Ti) diluted in isopropanol which is a common sol-gel route for fabricating TiOx electron selective contacts for ITO/TiOx inverted organic photovoltaics bottom electrodes. XPS Ti 2p and valence band spectra show the presence of additional features which are absent in spectra of titanium butoxide deposited on Si and are attributed to appearance of Ti^{3+} valence states in ITO/TiOx. This conclusion is confirmed by density functional theory electronic structure calculations of stoichiometric TiO2 and oxygen deficient TiO_{2-1/8}. XPS C 1s measurements show the formation of C-O and O-C=O bonds which evidence the presence of residual carbon which can draw oxygen from the film network and induce the formation of fraction of Ti3+ states in TiOx films.
Density Functional Theory (DFT) Study of Triphenylamine-Based Dyes for Their Use as Sensitizers in Molecular Photovoltaics  [PDF]
Jesús Baldenebro-López,José Castorena-González,Norma Flores-Holguín,Jorge Almaral-Sánchez,Daniel Glossman-Mitnik
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13044418
Abstract: In this work we studied three dyes which are proposed for potential photovoltaic applications and named Dye7, Dye7-2t and Dye7-3t. The Density Functional Theory (DFT) was utilized, using the M05-2X hybrid meta-GGA functional and the 6–31+G(d,p) basis set. This level of calculation was used to find the optimized molecular structure and to predict the main molecular vibrations, the absorption and emission spectra, the molecular orbitals energies, dipole moment, isotropic polarizability and the chemical reactivity parameters that arise from Conceptual DFT. Also, the p K a values were calculated with the semi-empirical PM6 method.
Review: Karakterisasi Nanomaterial
Mikrajuddin Abdullah,Khairurrijal
Jurnal Nanosains & Nanoteknologi , 2009,
Abstract: Pada paper ini akan dibahas sejumlah metode karakterisasi yang biasa digunakan dalam penelitian nanomaterial.
Carotenoids in Marine Animals  [PDF]
Takashi Maoka
Marine Drugs , 2011, DOI: 10.3390/md9020278
Abstract: Marine animals contain various carotenoids that show structural diversity. These marine animals accumulate carotenoids from foods such as algae and other animals and modify them through metabolic reactions. Many of the carotenoids present in marine animals are metabolites of β-carotene, fucoxanthin, peridinin, diatoxanthin, alloxanthin, and astaxanthin, etc. Carotenoids found in these animals provide the food chain as well as metabolic pathways. In the present review, I will describe marine animal carotenoids from natural product chemistry, metabolism, food chain, and chemosystematic viewpoints, and also describe new structural carotenoids isolated from marine animals over the last decade.
Key to Xenobiotic Carotenoids  [PDF]
Hans-Richard Sliwka,Vassilia Partali
Molecules , 2012, DOI: 10.3390/molecules17032877
Abstract: A listing of carotenoids with heteroatoms (X = F, Cl, Br, I, Si, N, S, Se, Fe) directly attached to the carotenoid carbon skeleton has been compiled. The 178 listed carotenoids with C,H,X atoms demonstrate that the classical division of carotenoids into hydrocarbon carotenoids (C,H) and xanthophylls (C,H,O) has become obsolete.
Inhibiting carotenoids
Wim D'Haeze
Genome Biology , 2002, DOI: 10.1186/gb-2002-3-6-reports0031
Abstract: Using PCR and primers designed against conserved regions within reported similar gene sequences, two copies of psy and one copy of pds were isolated from tobacco. The corresponding proteins show about 90% or more identity to those of described PSY and PDS proteins, respectively. The coding sequences of psy1, psy2, and pds were expressed in sense and antisense in transgenic tobacco plants, obtained by transformation mediated by Agrobacterium tumefaciens, and the effects on metabolism and phenotype were studied. Some plants overexpressing psy1 showed severe phenotypes, including dwarfism, changes in leaf pigmentation, a rolled appearance of the leaves, young leaves that appeared orange-colored, buds that were unable to flower, and flower-color changes. Overexpression of psy2 led to similar but less severe phenotypes in a number of plants. In plantsoverexpressing either psy1 or psy2, changes in carotenoid and chlorophyll content were noticed. In orange capsules that surround the seeds, for instance, the carotenoid content increased up to 400% and the chlorophyll content decreased to 6% as compared to green capsules. Antisense psy1 and psy2 expression did not show any significant phenotypes in primary transformants. Overexpression of pds did not cause any phenotypic or metabolic effects, in contrast to plants expressing pds antisense in which a dramatic accumulation of phytoene was noticed together with an increased carotenoid content. Some of the latter plants showed small white spots on their leaves, and white veins and leaf tips were noticed. Antisense expression of psy and pds was lethal for a population of transgenic plants.The study was performed at Bayer AG and more background information concerning the company can be found at the Bayer AG website.Busch et al. describe the effects of sense and antisense expression of two genes involved in the synthesis of carotenoids on tobacco phenotype and metabolism. Clearly, both the PSY and PDS enzymes can be used as targets
Quo Vadis photovoltaics 2011  [cached]
J?ger-Waldau A.
EPJ Photovoltaics , 2011, DOI: 10.1051/epjpv/2011005
Abstract: Since more than 10 years photovoltaics is one of the most dynamic industries with growth rates well beyond 40% per annum. This growth is driven not only by the progress in materials knowledge and processing technology, but also by market introduction programmes in many countries around the world. Despite the negative impacts on the economy by the financial crisis since 2009, photovoltaics is still growing at an extraordinary pace and had in 2010 an extraordinary success, as both production and markets doubled. The open question is what will happen in 2011 and the years after as the situation is dominated by huge manufacturing overcapacities and an increasing unpredictability of policy support. How can the PV industry continue their cost reduction to ensure another 10 to 20 years of sustained and strong growth necessary to make PV to one of the main pillars of a sustainable energy supply in 2030. Despite the fact, that globally the share of electricity from photovoltaic systems is still small, at local level it can be already now above 30% of the demand at certain times of the year. Future research in PV has to provide intelligent solutions not only on the solar cell alone, but also on the module and the system integration level in order to permit a 5 to 10% share of electricity in 2020.
Cancer Chemoprevention by Carotenoids  [PDF]
Takuji Tanaka,Masahito Shnimizu,Hisataka Moriwaki
Molecules , 2012, DOI: 10.3390/molecules17033202
Abstract: Carotenoids are natural fat-soluble pigments that provide bright coloration to plants and animals. Dietary intake of carotenoids is inversely associated with the risk of a variety of cancers in different tissues. Preclinical studies have shown that some carotenoids have potent antitumor effects both in vitro and in vivo, suggesting potential preventive and/or therapeutic roles for the compounds. Since chemoprevention is one of the most important strategies in the control of cancer development, molecular mechanism-based cancer chemoprevention using carotenoids seems to be an attractive approach. Various carotenoids, such as β-carotene, a-carotene, lycopene, lutein, zeaxanthin, β-cryptoxanthin, fucoxanthin, canthaxanthin and astaxanthin, have been proven to have anti-carcinogenic activity in several tissues, although high doses of β-carotene failed to exhibit chemopreventive activity in clinical trials. In this review, cancer prevention using carotenoids are reviewed and the possible mechanisms of action are described.
The Role of Carotenoids in Human Skin  [PDF]
Maxim E. Darvin,Wolfram Sterry,Juergen Lademann,Theognosia Vergou
Molecules , 2011, DOI: 10.3390/molecules161210491
Abstract: The human skin, as the boundary organ between the human body and the environment, is under the constant influence of free radicals (FR), both from the outside in and from the inside out. Carotenoids are known to be powerful antioxidant substances playing an essential role in the reactions of neutralization of FR (mainly reactive oxygen species ROS). Carotenoid molecules present in the tissue are capable of neutralizing several attacks of FR, especially ROS, and are then destroyed. Human skin contains carotenoids, such as α-, γ-, β-carotene, lutein, zeaxanthin, lycopene and their isomers, which serve the living cells as a protection against oxidation. Recent studies have reported the possibility to investigate carotenoids in human skin quickly and non-invasively by spectroscopic means. Results obtained from in-vivo studies on human skin have shown that carotenoids are vital components of the antioxidative protective system of the human skin and could serve as marker substances for the overall antioxidative status. Reflecting the nutritional and stress situation of volunteers, carotenoids must be administered by means of antioxidant-rich products, e.g., in the form of fruit and vegetables. Carotenoids are degraded by stress factors of any type, inter alia, sun radiation, contact with environmental hazards, illness, etc. The kinetics of the accumulation and degradation of carotenoids in the skin have been investigated.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.