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排序方式: 共有187条查询结果,搜索用时 15 毫秒
121.
Katryanne R. G. Bacca Natália F. Lopes Juliane B. Marcolino Fábio dos Santos Grasel Eleani M. da Costa 《工业材料与腐蚀》2020,71(1):155-165
The inhibitive behavior of Quebracho tannin extract on SAE 1010 steel corrosion in the acidic media is investigated. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) are first used to determine the inhibition efficiency of Quebracho in 0.1 M HCl solution to identify the best extract concentration to subsequently evaluate the inhibitor activity in CO2-rich aqueous solution at high pressure (15 MPa) and high temperature (70°C). Polarization curves revealed that Quebracho extract acted as cathodic inhibitor and that the inhibition efficiency is dependent on the extract concentration. The EIS measurements and SEM analysis showed that the inhibitor had been adsorbed on the steel surface. The inhibition efficiency of Quebracho in CO2 medium was similar to the 0.1 M HCl, reducing expressively the corrosion rate. The SEM images and X-ray diffraction analysis showed that iron carbonate was the main corrosion product formed on the metal surface in CO2-rich environment in the presence of Quebracho. Besides, the corrosion scale was thinner and more compact in the presence of inhibitor. 相似文献
122.
Call Josep; Br?uer Juliane; Kaminski Juliane; Tomasello Michael 《Canadian Metallurgical Quarterly》2003,117(3):257
Twelve domestic dogs (Canis familiaris) were given a series of trials in which they were forbidden to take a piece of visible food. In some trials, the human continued to look at the dog throughout the trial (control condition), whereas in others, the human (a) left the room, (b) turned her back, (c) engaged in a distracting activity, or (d) closed her eyes. Dogs behaved in clearly different ways in most of the conditions in which the human did not watch them compared with the control condition, in which she did. In particular, when the human looked at them, dogs retrieved less food, approached it in a more indirect way, and sat (as opposed to laid down) more often than in the other conditions. Results are discussed in terms of domestic dogs' social-cognitive skills and their unique evolutionary and ontogenetic histories. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
123.
(−)‐Tarchonanthuslactone: Design of New Analogues,Evaluation of their Antiproliferative Activity on Cancer Cell Lines,and Preliminary Mechanistic Studies
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Luiz Fernando Toneto Novaes Dr. Carolina Martins Avila Dr. Karin Juliane Pelizzaro‐Rocha Dr. Débora Barbosa Vendramini‐Costa Marina Pereira Dias Dr. Daniela Barreto Barbosa Trivella Prof. Dr. João Ernesto de Carvalho Prof. Dr. Carmen Veríssima Ferreira‐Halder Prof. Dr. Ronaldo Aloise Pilli 《ChemMedChem》2015,10(10):1687-1699
Natural products containing the α,β‐unsaturated δ‐lactone skeleton have been shown to possess a variety of biological activities. The natural product (?)‐tarchonanthuslactone ( 1 ) possessing this privileged scaffold is a popular synthetic target, but its biological activity remains underexplored. Herein, the total syntheses of dihydropyran‐2‐ones modeled on the structure of 1 were undertaken. These compounds were obtained in overall yields of 17–21 % based on the Keck asymmetric allylation reaction and were evaluated in vitro against eight different cultured human tumor cell lines. We further conducted initial investigation into the mechanism of action of selected analogues. Dihydropyran‐2‐one 8 [(S,E)‐(6‐oxo‐3,6‐dihydro‐2H‐pyran‐2‐yl)methyl 3‐(3,4‐dihydroxyphenyl)acrylate], a simplified analogue of (?)‐tarchonanthuslactone ( 1 ) bearing an additional electrophilic site and a catechol system, was the most cytotoxic and selective compound against six of the eight cancer cell lines analyzed, including the pancreatic cancer cell line. Preliminary studies on the mechanism of action of compound 8 on pancreatic cancer demonstrated that apoptotic cell death takes place mediated by an increase in the level of reactive oxygen species. It appears as though compound 8 , possessing two Michael acceptors and a catechol system, may be a promising scaffold for the selective killing of cancer cells, and thus, it deserves further investigation to determine its potential for cancer therapy. 相似文献
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127.
Luana Almeida Fiel Renata Vidor Contri Juliane Freitas Bica Fabrício Figueiró Ana Maria Oliveira Battastini Sílvia Stanis?uaski Guterres Adriana Raffin Pohlmann 《Nanoscale research letters》2014,9(1):233
The synthesis of novel fluorescent materials represents a very important step to obtain labeled nanoformulations in order to evaluate their biological behavior. The strategy of conjugating a fluorescent dye with triacylglycerol allows that either particles differing regarding supramolecular structure, i.e., nanoemulsions, nanocapsules, lipid-core nanocapsules, or surface charge, i.e., cationic nanocapsules and anionic nanocapsules, can be tracked using the same labeled material. In this way, a rhodamine B-conjugated triglyceride was obtained to prepare fluorescent polymeric nanocapsules. Different formulations were obtained, nanocapsules (NC) or lipid-core nanocapsules (LNC), using the labeled oil and Eudragit RS100, Eudragit S100, or poly(caprolactone) (PCL), respectively. The rhodamine B was coupled with the ricinolein by activating the carboxylic function using a carbodiimide derivative. Thin layer chromatography, proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FTIR), UV-vis, and fluorescence spectroscopy were used to identify the new product. Fluorescent nanocapsule aqueous suspensions were prepared by the solvent displacement method. Their pH values were 4.6 (NC-RS100), 3.5 (NC-S100), and 5.0 (LNC-PCL). The volume-weighted mean diameter (D4.3) and polydispersity values were 150 nm and 1.05 (NC-RS100), 350 nm and 2.28 (NC-S100), and 270 nm and 1.67 (LNC-PCL). The mean diameters determined by photon correlation spectroscopy (PCS) (z-average) were around 200 nm. The zeta potential values were +5.85 mV (NC-RS100), -21.12 mV (NC-S100), and -19.25 mV (LNC-PCL). The wavelengths of maximum fluorescence emission were 567 nm (NC-RS100 and LNC-PCL) and 574 nm (NC-S100). Fluorescence microscopy was used to evaluate the cell uptake (human macrophage cell line) of the fluorescent nanocapsules in order to show the applicability of the approach. When the cells were treated with the fluorescent nanocapsules, red emission was detected around the cell nucleus. We demonstrated that the rhodamine B-conjugated triglyceride is a promising new material to obtain versatile dye-labeled nanocarriers presenting different chemical nature in their surfaces. 相似文献
128.
Harnessing Enzymatic Promiscuity in Myxochelin Biosynthesis for the Production of 5‐Lipoxygenase Inhibitors
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Juliane Korp Stefanie König Dr. Sebastian Schieferdecker Dr. Hans‐Martin Dahse Prof. Dr. Gabriele M. König Prof. Dr. Oliver Werz Dr. Markus Nett 《Chembiochem : a European journal of chemical biology》2015,16(17):2445-2450
The siderophore myxochelin A is a potent inhibitor of human 5‐lipoxygenase (5‐LO). To clarify whether the iron‐chelating properties of myxochelin A are responsible for this activity, several analogues of this compound were generated in the native producer Pyxidicoccus fallax by precursor‐directed biosynthesis. Testing in a cell‐free assay unveiled three derivatives with bioactivity comparable with that of myxochelin A. Furthermore, it became evident that inhibition of 5‐LO by myxochelins does not correlate with their iron affinities. 相似文献
129.
Paul Chekhonin Benoît Beausir Juliane Scharnweber Carl-Georg Oertel Tina Hausöl Heinz Werner Höppel Heinz-Günter Brokmeier Werner Skrotzki 《Acta Materialia》2012,60(11):4661-4671
Aluminium laminates consisting of high-purity aluminium and commercially pure aluminium have been produced by accumulative roll bonding (ARB) at ambient temperature for up to 10 cycles. To study the microstructure and texture development of the high-purity aluminium layers with regard to the shrinking layer thickness during ARB, microstructure and texture investigations were carried out by electron backscatter diffraction and neutron and X-ray diffraction, respectively. While the commercially pure aluminium layers develop an ultrafine-grained microstructure, partial discontinuous recrystallization occurs in the high-purity layers. The texture of the high-purity layers mainly consists of Cube and “Tilted Cube” (tilted with respect to the transverse direction) components. The experimental results are discussed with respect to confined recrystallization in the ARB aluminium laminates. 相似文献
130.
Commercial scanning white light interference microscopes are able to map surface topography to very high resolution and can thus measure very small amounts of wear on rubbed surfaces. These instruments are therefore being increasingly used to study aspects of mild wear. It is shown in this Technical Note that, when used on surfaces that have been rubbed in lubricants containing the antiwear additive zinc dialkyldithiophosphate (ZDDP), some white light interference microscopes can produce an apparent but spurious wear measurement. The transparent and relatively thick antiwear film generated by ZDDP on rubbed surfaces produces an optical path difference that is incorrectly interpreted as wear. It is thus suggested that surfaces that have been rubbed in lubricants containing ZDDP or other thick film-forming additives should be treated to remove tribofilms prior to wear measurement using scanning interference microscopy. 相似文献