984 resultados para three-photon absorption


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Several alkylidene malononitriles (1b,1d,1e,2b and4b) and alkylidene cyanoacetates (1a,2a and4a) studied exhibit a long wavelength UV absorption band around 355 nm which shows a hyperchromic effect in the presence of ethanolic alkali. This band has been assigned to the ketenimine tautomer (5). Addition of water to1b,1e and2b gives the corresponding pyridine diols (7a,7b and8a) respectively. Similarly, addition of ethanol to1e and2b gave the corresponding ethoxypyridine derivatives (7c and8b). Mechanism of formation of these compounds is discussed. Structures, as well as mechanism of formation of1c,7c and10 obtained from1b,1e and2b respectively on standing at room temperature are also discussed.

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Several alkylidene malononitriles (1b,1d,1e,2b and4b) and alkylidene cyanoacetates (1a,2a and4a) studied exhibit a long wavelength UV absorption band around 355 nm which shows a hyperchromic effect in the presence of ethanolic alkali. This band has been assigned to the ketenimine tautomer (5). Addition of water to1b,1e and2b gives the corresponding pyridine diols (7a,7b and8a) respectively. Similarly, addition of ethanol to1e and2b gave the corresponding ethoxypyridine derivatives (7c and8b). Mechanism of formation of these compounds is discussed. Structures, as well as mechanism of formation of1c,7c and10 obtained from1b,1e and2b respectively on standing at room temperature are also discussed.

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IR absorption spectra of As-Se glasses have been studied over a wide range of compositions. Various two-phonon, multiphonon (combination tones) and impurity absorptions have been identified. Compositional variation of relative band intensities has been explained in terms of the chemically ordered network model.

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X-ray absorption edge and X-ray photoelectron spectroscopic studies of As-Se glasses seem to support a chemical ordering model.

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A method of analysing a 3-dimensional corner reflector antenna of arbitrary apex angle is given. Expressions have been obtained for the far field of the 3-dimensional corner reflector fed by a dipole. The radiation resistance and the directive gain of the antenna have been calculated. The method described is applicable even when the feed dipole is arbitrarily oriented. It is found that the radiation along a prescribed direction can be circularly polarised (right or left) by suitably orienting the feed dipole.

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1. The mechanism of absorption of phosphatidylcholine was studied in rats by injecting into the intestine phosphatidylcholine specifically labelled either in the fatty acid or in the glycerol moiety or with 32P, when considerable amounts of 1-acyl-lysophosphatidylcholine were found in the intestinal lumen. 2-([14C]Acyl)phosphatidylcholine gave markedly more radioactive unesterified fatty acids in the lumen, compared with the 1-([14C]acyl) derivative. Some of the radioactivity from either the fatty acid or the glycerol moiety of the injected phosphatidylcholine appeared in the mucosal triacylglycerols. 2. Injection of 32P-labelled phosphatidylcholine or 32P-labelled lysophosphatidylcholine led to the appearance of radioactive glycerylphosphorylcholine, glycerophosphate and Pi in the mucosa. 3. Rat mucosa was found to contain a highly active glycerylphosphorylcholine diesterase. 4. It was concluded that the dietary phosphatidylcholine is hydrolysed in the intestinal lumen by the pancreatic phospholipase A to 1-acylglycerylphosphorylcholine, which on entering the mucosal cell is partly reacylated to phosphatidylcholine, and the rest is further hydrolysed to glycerylphosphorylcholine, glycerophosphate, glycerol and Pi. The fatty acids and glycerophosphate are then reassembled to give triacylglycerols via the Kennedy (1961) pathway.

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Historically, two-dimensional (2D) cell culture has been the preferred method of producing disease models in vitro. Recently, there has been a move away from 2D culture in favor of generating three-dimensional (3D) multicellular structures, which are thought to be more representative of the in vivo environment. This transition has brought with it an influx of technologies capable of producing these structures in various ways. However, it is becoming evident that many of these technologies do not perform well in automated in vitro drug discovery units. We believe that this is a result of their incompatibility with high-throughput screening (HTS). In this study, we review a number of technologies, which are currently available for producing in vitro 3D disease models. We assess their amenability with high-content screening and HTS and highlight our own work in attempting to address many of the practical problems that are hampering the successful deployment of 3D cell systems in mainstream research.

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Proton NMR spectroscopy in three different liquid crystals has been used to determine two conformational angles of (μ-butatriene)hexacarbonyldiiron complex, namely the angle between the two CH2 planes and the dihedral angle between the two planes containing four carbon atoms of the butatriene moiety. The values are 44 and 46°, respectively. The direct and the indirect geminal HH couplings are shown to be of the same sign in the liquid crystals with positive diamagnetic anisotropy.

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The tomato I-3 and I-7 genes confer resistance to Fusarium oxysporum f. sp. lycopersici (Fol) race 3 and were introgressed into the cultivated tomato, Solanum lycopersicum, from the wild relative Solanum pennellii. I-3 has been identified previously on chromosome 7 and encodes an S-receptor-like kinase, but little is known about I-7. Molecular markers have been developed for the marker-assisted breeding of I-3, but none are available for I-7. We used an RNA-seq and single nucleotide polymorphism (SNP) analysis approach to map I-7 to a small introgression of S. pennellii DNA (c. 210 kb) on chromosome 8, and identified I-7 as a gene encoding a leucine-rich repeat receptor-like protein (LRR-RLP), thereby expanding the repertoire of resistance protein classes conferring resistance to Fol. Using an eds1 mutant of tomato, we showed that I-7, like many other LRR-RLPs conferring pathogen resistance in tomato, is EDS1 (Enhanced Disease Susceptibility 1) dependent. Using transgenic tomato plants carrying only the I-7 gene for Fol resistance, we found that I-7 also confers resistance to Fol races 1 and 2. Given that Fol race 1 carries Avr1, resistance to Fol race 1 indicates that I-7-mediated resistance, unlike I-2- or I-3-mediated resistance, is not suppressed by Avr1. This suggests that Avr1 is not a general suppressor of Fol resistance in tomato, leading us to hypothesize that Avr1 may be acting against an EDS1-independent pathway for resistance activation. The identification of I-7 has allowed us to develop molecular markers for marker-assisted breeding of both genes currently known to confer Fol race 3 resistance (I-3 and I-7). Given that I-7-mediated resistance is not suppressed by Avr1, I-7 may be a useful addition to I-3 in the tomato breeder's toolbox.

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Three-component metal-inorganic assembly of a Co(II) network representing the first example of a 3D coordination polymer containing a hydrazine bridging ligand, has been synthesized and characterized.

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Serial Block-Face Scanning Electron Microscopy (SBF-SEM) was used in this study to examine the ultrastructural morphology of Penaeus monodon spermatozoa. SBF-SEM provided a large dataset of sequential electron-microscopic-level images that facilitated comprehensive ultrastructural observations and three-dimensional reconstructions of the sperm cell. Reconstruction divulged a nuclear region of the spermatophoral spermatozoon filled with decondensed chromatin but with two apparent levels of packaging density. In addition, the nuclear region contained, not only numerous filamentous chromatin elements with dense microregions, but also large centrally gathered granular masses. Analysis of the sperm cytoplasm revealed the presence of degenerated mitochondria and membrane-less dense granules. A large electron-lucent vesicle and "arch-like" structures were apparent in the subacrosomal area, and an acrosomal core was found in the acrosomal vesicle. The spermatozoal spike arose from the inner membrane of the acrosomal vesicle, which was slightly bulbous in the middle region of the acrosomal vesicle, but then extended distally into a broad dense plate and to a sharp point proximally. This study has demonstrated that SBF-SEM is a powerful technique for the 3D ultrastructural reconstruction of prawn spermatozoa, that will no doubt be informative for further studies of sperm assessment, reproductive pathology and the spermiocladistics of penaeid prawns, and other decapod crustaceans. J. Morphol., 2016. (c) 2016 Wiley Periodicals, Inc.

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Mixed valency in CePd3 has been examined by a study of the LIII (Ce) absorption edge in this compound as well as other model compounds. In CePd3, peaks characteristic of 3+ and 4+ states of Ce are found to be separated by 2 eV.

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An iterative algorithm baaed on probabilistic estimation is described for obtaining the minimum-norm solution of a very large, consistent, linear system of equations AX = g where A is an (m times n) matrix with non-negative elements, x and g are respectively (n times 1) and (m times 1) vectors with positive components.

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This study addresses the following question: How to think about ethics in a technological world? The question is treated first thematically by framing central issues in the relationship between ethics and technology. This relationship has three distinct facets: i) technological advance poses new challenges for ethics, ii) traditional ethics may become poorly applicable in a technologically transformed world, and iii) the progress in science and technology has altered the concept of rationality in ways that undermine ethical thinking itself. The thematic treatment is followed by the description and analysis of three approaches to the questions framed. First, Hans Jonas s thinking on the ontology of life and the imperative of responsibility is studied. In Jonas s analysis modern culture is found to be nihilistic because it is unable to understand organic life, to find meaning in reality, and to justify morals. At the root of nihilism Jonas finds dualism, the traditional Western way of seeing consciousness as radically separate from the material world. Jonas attempts to create a metaphysical grounding for an ethic that would take the technologically increased human powers into account and make the responsibility for future generations meaningful and justified. The second approach is Albert Borgmann s philosophy of technology that mainly assesses the ways in which technological development has affected everyday life. Borgmann admits that modern technology has liberated humans from toil, disease, danger, and sickness. Furthermore, liberal democracy, possibilities for self-realization, and many of the freedoms we now enjoy would not be possible on a large scale without technology. Borgmann, however, argues that modern technology in itself does not provide a whole and meaningful life. In fact, technological conditions are often detrimental to the good life. Integrity in life, according to him, is to be sought among things and practices that evade technoscientific objectification and commodification. Larry Hickman s Deweyan philosophy of technology is the third approach under scrutiny. Central in Hickman s thinking is a broad definition of technology that is nearly equal to Deweyan inquiry. Inquiry refers to the reflective and experiential way humans adapt to their environment by modifying their habits and beliefs. In Hickman s work, technology consists of all kinds of activities that through experimentation and/or reflection aim at improving human techniques and habits. Thus, in addition to research and development, many arts and political reforms are technological for Hickman. He argues for recasting such distinctions as fact/value, poiesis/praxis/theoria, and individual/society. Finally, Hickman does not admit a categorical difference between ethics and technology: moral values and norms need to be submitted to experiential inquiry as well as all the other notions. This study mainly argues for an interdisciplinary approach to the ethics of technology. This approach should make use of the potentialities of the research traditions in applied ethics, the philosophy of technology, and the social studies on science and technology and attempt to overcome their limitations. This study also advocates an endorsement of mid-level ethics that concentrate on the practices, institutions, and policies of temporal human life. Mid-level describes the realm between the instantaneous and individualistic micro-level and the universal and global macro level.