1,720,960 research outputs found
Fe2+ promoted peroxidation of 1,2-diacyl-sn-glycero-3-phosphocholine liposomes in the presence of calf thymus DNA.
No full textThe peroxidation reaction of some liposomes, namely egg yolk phosphatidylcholine (PC), dioleoyl- (DOPC) and dilinoleoyl- (DLPC) phosphocholines, promoted by ferrous ions (Fenton reaction) has been studied at the physiological pH value, in the absence and in the presence of calf thymus DNA. A catalytic effect of DNA, where the lag time reduces or is completely annihilated, together with an increase in both the yields and the rates of the reactions, has been observed. This effect of DNA has been attributed to the ability of the three components, liposomes, DNA and Fe2+, to form a stable ternary complex, which produces a reduction of the undulatory fluctuations of the hydrocarbon tails of liposomes and strengthens the packing between the acyl chains in the lipid bilayers, with the consequence of enhancing the liposome crystallinity
X-ray diffraction study of dioleoylphosphatidylcholine-DNA-Mn2+ complexes
No full textWe have studied the structural properties of the triple complex dioleoylphosphatidylcholine-DNA-Mn2+ by means of synchrotron x-ray diffraction. The data revel a novel multilamellar structure similar to that recently found in cationic liposomes-DNA complexes. ne study of the bilayer undulations suggests that condensation of the DNA within the lipid bilayers reduces the flexibility of the lamellae in the complex and suppresses almost completely the undulatory fluctuations. These complexes are of grate interest for potential applications as synthetically-based nonviral carriers of DNA vectors for gene therapy
CYLINDRICAL INTERNAL REFLECTANCE FT-IR. INTERACTIONS BETWEEN COMPONENTS OF BIOLOGICAL MOLECULES AND METAL IONS. II.
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Nitrenium Ions Part 2. Acid-catalyzed Reactions of Indole with Nitrosobenzenes. Crystal Structure of 2-(indol-3-yl)-3-phenylimino-3H-indole
No full textAbstract: The reactions of indole with nitrosobenzenes in the presence of monochloroacetic acid have been studied demonstrating the existence of nitrenium ions; the structure of 2-(indol-3-yl)-3-phenylimino-H-3-indole has been determined by X-ray crystallography.
JOURNAL OF CHEMICAL RESEARCH, Miniprint (M), 1924-1945
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Structure of self-assembled liposome-DNA-metal complexes
No full textWe have studied the structural and morphological properties of the triple complex dioleoyl phosphatidylcholine (DOPC)-DNA-Mn(2+) by means of synchrotron x-ray diffraction and freeze-fracture transmission electron microscopy. This complex is formed in a self-assembled manner when water solutions of neutral lipid, DNA, and metal ions are mixed, which represents a striking example of supramolecular chemistry. The DNA condensation in the complex is promoted by the metal cations that bind the polar heads of the lipid with the negatively charged phosphate groups of DNA. The complex is rather heterogeneous with respect to size and shape and exhibits the lamellar symmetry of the L(alpha)(c) phase: the structure consists of an ordered multilamellar assembly similar to that recently found in cationic liposome-DNA complexes, where the hydrated DNA helices are sandwiched between the liposome bilayers. The experimental results show that, at equilibrium, globules of the triple complex in the L(alpha)(c) phase coexist with globules of multilamellar vesicles of DOPC in the L(alpha) phase, the volume ratio of the two structures being dependent on the molar ratio of the three components DOPC, DNA, and Mn(2+). These complexes are of potential interest for applications as synthetically based nonviral carriers of DNA vectors for gene therapy
Competition between Nucleophylic Addition and Electron-Transfer Process in the Reaction of 9-Diazo-10-Anthrone with Grignard Reagents
No full textVariations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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