952 resultados para dichloromethane substitution
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Vanadium Oxide has been a frontrunner in the field of oxide electronics because of its metal-insulator transition (MIT). The interplay of different structures of VO2 has played a crucial role in deciding the magnitude of the first order MIT. Substitution doping has been found to introduce different polymorphs of VO2. Hence the role of substitution doping in stabilizing the competing phases of VO2 in the thin film form remains underexplored. Consequently there have been reports both discounting and approving such a stabilization of competing phases in VO2. It is reported in the literature that the bandwidth of the hysteresis and transition temperature of VO2 can be tuned by substitutional doping of VO2 with W. In this work, we have adopted a novel technique called, Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM) to deposit VO2 and W- doped VO2 as thin films. XRD and Raman spectroscopy were used to investigate the role of tungsten on the structure of VO2 thin films. Morphology of the thin films was found to be consisting of globular and porous nanoparticles of size similar to 20nm. Transition temperature decreased with the addition of W. We found that for 2.0 at % W doping in VO2, the transition temperature has reduced from 68 degrees C to 25 degrees C. It is noted that W-doping in the process of reducing the transition temperature, alters the local structure and also increases room temperature carrier concentration. (c) 2016 Author(s).
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As one of the most abundant polysaccharides on Earth, xylan will provide more than a third of the sugars for lignocellulosic biofuel production when using grass or hardwood feedstocks. Xylan is characterized by a linear β(1,4)-linked backbone of xylosyl residues substituted by glucuronic acid, 4-O-methylglucuronic acid or arabinose, depending on plant species and cell types. The biological role of these decorations is unclear, but they have a major influence on the properties of the polysaccharide. Despite the recent isolation of several mutants with reduced backbone, the mechanisms of xylan synthesis and substitution are unclear. We identified two Golgi-localized putative glycosyltransferases, GlucUronic acid substitution of Xylan (GUX)-1 and GUX2 that are required for the addition of both glucuronic acid and 4-O-methylglucuronic acid branches to xylan in Arabidopsis stem cell walls. The gux1 gux2 double mutants show loss of xylan glucuronyltransferase activity and lack almost all detectable xylan substitution. Unexpectedly, they show no change in xylan backbone quantity, indicating that backbone synthesis and substitution can be uncoupled. Although the stems are weakened, the xylem vessels are not collapsed, and the plants grow to normal size. The xylan in these plants shows improved extractability from the cell wall, is composed of a single monosaccharide, and requires fewer enzymes for complete hydrolysis. These findings have implications for our understanding of the synthesis and function of xylan in plants. The results also demonstrate the potential for manipulating and simplifying the structure of xylan to improve the properties of lignocellulose for bioenergy and other uses.
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Here we attempt to characterize protein evolution by residue features which dominate residue substitution in homologous proteins. Evolutionary information contained in residue substitution matrix is abstracted with the method of eigenvalue decomposition. Top eigenvectors in the eigenvalue spectrums are analyzed as function of the level of similarity, i.e. sequence identity (SI) between homologous proteins. It is found that hydrophobicity and volume are two significant residue features conserved in protein evolution. There is a transition point at SI approximate to 45%. Residue hydrophobicity is a feature governing residue substitution as SI >= 45%. Whereas below this SI level, residue volume is a dominant feature. (C) 2007 Elsevier B.V. All rights reserved.
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CLEMAPS is a tool for multiple alignment of protein structures. It distinguishes itself from other existing algorithms for multiple structure alignment by the use of conformational letters, which are discretized states of 3D segmental structural states. A letter corresponds to a cluster of combinations of three angles formed by C-alpha pseudobonds of four contiguous residues. A substitution matrix called CLESUM is available to measure the similarity between any two such letters. The input 3D structures are first converted to sequences of conformational letters. Each string of a fixed length is then taken as the center seed to search other sequences for neighbors of the seed, which are strings similar to the seed. A seed and its neighbors form a center-star, which corresponds to a fragment set of local structural similarity shared by many proteins. The detection of center-stars using CLESUM is extremely efficient. Local similarity is a necessary, but insufficient, condition for structural alignment. Once center-stars are found, the spatial consistency between any two stars are examined to find consistent star duads using atomic coordinates. Consistent duads are later joined to create a core for multiple alignment, which is further polished to produce the final alignment. The utility of CLEMAPS is tested on various protein structure ensembles.
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Resumen: Este estudio analiza la teoría aristotélica de la abstracción, tratando de rescatar su sentido originario a partir de los textos del autor, así como los aportes de los aristotélicos medievales más relevantes, especialmente Tomás de Aquino. Y luego se pasa a describir algunos hitos fundamentales de la evolución posterior de dicha teoría en la historia de la Filosofía, como son: 1) La contraposición entre abstracción e intuición en Duns Escoto y Guillermo de Ockham. 2) el intuicionismo de Descartes 3) La reinterpretación empirista de la abstracción en J. Locke 4) La ausencia de la abstracción en el Espinoza, Leibniz y Kant, así como su sustitución por la “aufhebung” en Hegel. 5) La peculiar aproximación husserliana a la abstracción a partir de su método fenomenológico y 6) la relación de la teoría de la abstracción con el pensamiento de algunos autores contemporáneos como Zubiri, Polo y, especialmente, Heidegger.
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The stationary two-dimensional (x, z) near wakes behind a flat-based projectile which moves at a constant mesothermal speed (V∞) along a z-axis in a rarefied, fully ionized, plasma is studied using the wave model previously proposed by one of the authors (VCL). One-fluid theory is used to depict the free expansion of ambient plasma into the vacuum produced behind a fast-moving projectile. This nonstationary, one-dimensional (x, t) flow which is approximated by the K-dV equation can be transformed, through substitution, t=z/V∞, into a stationary two-dimensional (x, z) near wake flow seen by an observer moving with the body velocity (V∞). The initial value problem of the K-dV equation in (x, t) variables is solved by a specially devised numerical method. Comparisons of the present numerical solution for the asymptotically small and large times with available analytical solutions are made and found in satisfactory agreements.
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The aim of this paper is to analyze how active R&D policies affect the growth rate of an economy with endogenous growth and non-renewable resources. We know from Scholz and Ziemens (1999) and Groth (2006) that in infinitely lived agents (ILA) economies, any active R&D policy increases the growth rate of the economy. To see if this result also appears in economies with finite lifetime agents, we developed an endogenous growth overlapping generations (OLG) economy à la Diamond which uses non-renewable resources as essential inputs in final good’s production. We show analytically that any R&D policy that reduces the use of natural resources implies a raise in the growth rate of the economy. Numerically we show that in economies with low intertemporal elasticity of substitution (IES), active R&D policies lead the economy to increase the depletion of non-renewable resources. Nevertheless, we find that active R&D policies always imply increases in the endogenous growth rate, in both scenarios. Furthermore, when the IES coefficient is lower (greater) than one, active R&D policies affect the growth rate of the economy in the ILA more (less) than in OLG economies.
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Using the ECHP, we explored the determinants of having the first child in Spain. Our main goal was to study the relation between female wages and the decision to enter motherhood. Since the offered wage of non-working women is not observed, we estimate it and impute a potential wage to each woman (working and non-working). This potential wage enable us to investigate the effect of wages (the opportunity cost of time non-worked and dedicated to children) on the decision to have the first child, for both workers and non-workers. Contrary to previous results, we found that female wages are positively related to the likelihood of having the first child. This result suggests that the income effect overcomes the substitution effect when non-participants opportunity cost is also taken into account.
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This paper investigates the exploitation of environmental resources in a growing economy within a second-best scal policy framework. Agents derive utility from two types of consumption goods one which relies on an environmental input and one which does not as well as from leisure and from environmental amenity values. Property rights for the environmental resource are potentially incomplete. We connect second best policy to essential components of utility by considering the elasticity of substitution among each of the four utility arguments. The results illustrate potentially important relationships between environmental amentity values and leisure. When amenity values are complementary with leisure, for instance when environmental amenities are used for recreation, taxes on extractive goods generally increase over time. On the other hand, optimal taxes on extractive goods generally decrease over time when leisure and environmental amenity values are substitutes. Unders some parameterizations, complex dynamics leading to nonmonotonic time paths for the state variables can emerge.
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As medidas provisórias passaram a integrar o processo legislativo brasileiro com o advento da Constituição de 1988. A previsão inicial das medidas provisórias no art. 62 da Constituição Federal foi se tornando insatisfatória por deficiências oriundas dos pressupostos de relevância e urgência, em razão dos mesmos terem sido aferidos como muito genéricos ou subjetivos, o que acarretou sua demasiada edição. Com o intuito de restringir o poder do chefe do Executivo, foi aprovada, a Emenda Constitucional n. 32/2002, regulamentada pela Resolução 01/2002 do Congresso Nacional. Há consenso geral sobre a afronta estabelecida ao processo legislativo em função da perda de competência do Congresso derivada da excessiva edição de medidas provisórias, sendo necessário limitar essa prejudicial atuação executiva que tem estabelecido o trancamento de pauta constante nas votações no Parlamento.
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[ES] Cada vez más el deporte-espectáculo se está abriendo paso como objeto de estudio en los centros de investigación avanzada, como consecuencia de la necesidad de gestionar los altos presupuestos de las entidades deportivas.
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[ES]La sustitución de los millones por el crecimiento en el precio de la sal que Felipe IV estableció en 1631 provocó reacciones generalizadas en toda Castilla, y en particular entre las provincias que se hallaban exentas de pagarlos. Son conocidos los violentos disturbios de Vizcaya. En cambio, poco se sabe acerca de lo sucedido en las otras dos Provincias Exentas. El presente artículo analiza, en conjunto, la actitud que tanto Vizcaya como Guipúzcoa y Álava adoptaron ante el nuevo impuesto. Aunque las tres coincidieron en rechazarlo, lo hicieron mediante discursos y métodos bien diferentes. No en vano, lejos de lo que suele pensarse no gozaban de una plena equiparación fiscal ni jurídica.
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[EN]A study was conducted on crossbred steers (n=275; 376±924 kg) to evaluate performance and carcass quality of cattle fed wheat or corn dried distillers’ grains with solubles (DDGS). The control ration contained 86.6% rolled barley grain, 5.7% supplement and 7.7% barley silage (DM basis). The four treatments included replacement of barley grain at 20 or 40% of the diet (DM basis) with wheat or corn DDGS. Steers were slaughtered at a common end weight of 645 kg with 100 steers randomly (n=20 per treatment) selected for determination of the retail yield of sub-primal boneless boxed beef (SPBBB). Data were analyzed as a completely randomized design using pen as the experimental unit. Feeding increasing levels of wheat DDGS led to a quadratic increase in dry matter intake (DMI) (P<0.01), whereas increasing levels of corn DDGS led to a quadratic decrease in DMI (P=0.01). Average daily gain was not influenced (P=0.13) by feeding wheat or corn DDGS, but cattle fed corn DDGS exhibited a quadratic increase (P=0.01) in gain:feed. As a result, a quadratic increase (P<0.01) in calculated NEg of the diet was observed as corn DDGS levels increased. A linear decrease (P=0.04) in days on feed (169, 166 and 154 d) was noted when increasing levels of wheat DDGS (0, 20 and 40%) were fed. Dressing percentage increased in a linear fashion with wheat DDGS (P<0.01) inclusion level and in a quadratic fashion (P=0.01) as corn DDGS inclusion level increased although other carcass traits were not affected (P=0.10) by treatment. The results indicate that replacement of barley grain with corn or wheat DDGS up to 40% of the diet (DM) can lead to superior performance (improved gain:feed or reduced days on feed, respectively) with no detrimental effect on quality grade or carcass SPBBB yield.
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We analyze the effects of capital income taxation on long-run growth in a stochastic, two-period overlapping generations economy. Endogenous growth is driven by a positive externality of physical capital in the production sector that makes firms exhibit an aggregate technology in equilibrium. We distinguish between capital income and labor income, and between attitudes towards risk and intertemporal substitution of consumption. We show necessary and sufficient conditions such that i) increments in the capital income taxation lead to higher equilibrium growth rates, and ii) the effect of changes in the capital income tax rate on the equilibrium growth may be of opposite signs in stochastic and in deterministic economies. Such a sign reversal is shown to be more likely depending on i) how the intertemporal elasticity of substitution compares to one, and ii) the size of second- period labor supply. Numerical simulations show that for reasonable values of the intertemporal elasticity of substitution, a sign reversal shows up only for implausibly high values of the second- period’s labor supply. The conclusion is that deterministic OLG economies are a good approximation of the effect of taxes on the equilibrium growth rate as in Smith (1996).
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9 p.