927 resultados para Very fast radical probe


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Database management systems offer a very reliable and attractive data organization for fast and economical information storage and processing for diverse applications. It is much more important that the information should be easily accessible to users with varied backgrounds, professional as well as casual, through a suitable data sublanguage. The language adopted here (APPLE) is one such language for relational database systems and is completely nonprocedural and well suited to users with minimum or no programming background. This is supported by an access path model which permits the user to formulate completely nonprocedural queries expressed solely in terms of attribute names. The data description language (DDL) and data manipulation language (DML) features of APPLE are also discussed. The underlying relational database has been implemented with the help of the DATATRIEVE-11 utility for record and domain definition which is available on the PDP-11/35. The package is coded in Pascal and MACRO-11. Further, most of the limitations of the DATATRIEVE-11 utility have been eliminated in the interface package.

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A profluorescent nitroxide possessing an isoindoline nitroxide moiety linked to a perylene fluorophore was developed to monitor radical mediated degradation of melamine-formaldehyde crosslinked polyester coil coatings in an industry standard accelerated weathering tester. Trapping of polyester-derived radicals (most likely C-radicals) that are generated during polymer degradation leads to fluorescent closed-shell alkoxy amines, which was used to obtain time-dependent degradation profiles to assess the relative stability of different polyesters towards weathering. The nitroxide probe couples excellent thermal stability and satisfactory photostability with high sensitivity and enables detection of free radical damage in polyesters under conditions that mimic exposure to the environment on a time scale of hours rather than months or years required by other testing methods. There are indications that the profluorescent nitroxide undergoes partial photo-degradation in the absence of polymer-derived radicals. Unexpectedly, it was also found that UV-induced fragmentation of the NO–C bond in closed-shell alkoxy amines leads to regeneration of the profluorescent nitroxide and the respective C-radical. The maximum fluorescence intensity that could be achieved with a given probe concentration is therefore not only determined by the amount of polyester radicals formed during accelerated weathering, but also by the light-driven side reactions of the profluorescent nitroxide and the corresponding alkoxy amine radical trapping products. Studies to determine the optimum probe concentration in the polymer matrix revealed that aggregation and re-absorption effects lowered the fluorescence intensity at higher concentrations of the profluorescent nitroxide, but too low probe concentrations, where these effects would be avoided, were not sufficient to trap the amount of polyester radicals formed upon weathering. The optimized experimental conditions were used to assess the impact of temperature and UV irradiance on polymer degradation during accelerated weathering.

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In a previous paper, we described the room temperature rapid, selective, reversible, and near quantitative Cu-activated nitroxide radical coupling (NRC) technique to prepare 3-arm polystyrene stars. In this work, we evaluated the Cu-activation mechanism, either conventional atom transfer or single electron transfer (SET), through kinetic simulations. Simulation data showed that one can describe the system by either activation mechanism. We also found through simulations that bimolecular radical termination, regardless of activation mechanism, was extremely low and could be considered negligible in an NRC reaction. Experiments were carried out to form 2- and 3-arm PSTY stars using two ligands, PMDETA and Me6TREN, in a range of solvent conditions by varying the ratio of DMSO to toluene, and over a wide temperature range. The rate of 2- or 3-arm star formation was governed by the choice of solvent and ligand. The combination of Me6TREN and toluene/DMSO showed a relatively temperature independent rate, and remarkably reached near quantitative yields for 2-arm star formation after only 1 min at 25 °C.

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The single electron transfer-nitroxide radical coupling (SET-NRC) reaction has been used to produce multiblock polymers with high molecular weights in under 3 min at 50◦C by coupling a difunctional telechelic polystyrene (Br-PSTY-Br)with a dinitroxide. The well known combination of dimethyl sulfoxide as solvent and Me6TREN as ligand facilitated the in situ disproportionation of CuIBr to the highly active nascent Cu0 species. This SET reaction allowed polymeric radicals to be rapidly formed from their corresponding halide end-groups. Trapping of these carbon-centred radicals at close to diffusion controlled rates by dinitroxides resulted in high-molecular-weight multiblock polymers. Our results showed that the disproportionation of CuI was critical in obtaining these ultrafast reactions, and confirmed that activation was primarily through Cu0. We took advantage of the reversibility of the NRC reaction at elevated temperatures to decouple the multiblock back to the original PSTY building block through capping the chain-ends with mono-functional nitroxides. These alkoxyamine end-groups were further exchanged with an alkyne mono-functional nitroxide (TEMPO–≡) and ‘clicked’ by a CuI-catalyzed azide/alkyne cycloaddition (CuAAC) reaction with N3–PSTY–N3 to reform the multiblocks. This final ‘click’ reaction, even after the consecutive decoupling and nitroxide-exchange reactions, still produced high molecular-weight multiblocks efficiently. These SET-NRC reactions would have ideal applications in re-usable plastics and possibly as self-healing materials.

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High activation of polystyrene with bromine end groups (PSTY-Br) to their incipient radicals occurred in the presence of Cu(I)Br, Me6TREN, and DMSO solvent. These radicals were then trapped by nitroxide species leading to coupling reactions between PSTY-Br and nitroxides that were ultrafast and selective in the presence of a diverse range of functional groups. The nitroxide radical coupling (NRC) reactions have the attributes of a “click” reaction with near quantitative yields of product formed, but through the reversibility of this reaction, it has the added advantage of permitting the exchange of chemical functionality on macromolecules. Conditions were chosen to facilitate the disproportionation of Cu(I)Br to the highly activating nascent Cu(0) and deactivating Cu(II)Br2 in the presence of DMSO solvent and Me6TREN ligand. NRC at room temperature gave near quantitative yields of macromolecular coupling of low molecular weight polystyrene with bromine chain-ends (PSTY-Br) and nitroxides in under 7 min even in the presence of functional groups (e.g., −≡, −OH, −COOH, −NH2, =O). Utilization of the reversibility of the NRC reaction at elevated temperatures allowed the exchange of chain-end groups with a variety of functional nitroxide derivatives. The robustness and orthogonality of this NRC reaction were further demonstrated using the Cu-catalyzed azide/alkyne “click” (CuAAC) reactions, in which yields greater than 95% were observed for coupling between PSTY-N3 and a PSTY chain first trapped with an alkyne functional TEMPO (PSTY-TEMPO-≡).

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Earlier studies have shown that the speed of information transmission developed radically during the 19th century. The fast development was mainly due to the change from sailing ships and horse-driven coaches to steamers and railways, as well as the telegraph. Speed of information transmission has normally been measured by calculating the duration between writing and receiving a letter, or between an important event and the time when the news was published elsewhere. As overseas mail was generally carried by ships, the history of communications and maritime history are closely related. This study also brings a postal historical aspect to the academic discussion. Additionally, there is another new aspect included. In business enterprises, information flows generally consisted of multiple transactions. Although fast one-way information was often crucial, e.g. news of a changing market situation, at least equally important was that there was a possibility to react rapidly. To examine the development of business information transmission, the duration of mail transport has been measured by a systematic and commensurable method, using consecutive information circles per year as the principal tool for measurement. The study covers a period of six decades, several of the world's most important trade routes and different mail-carrying systems operated by merchant ships, sailing packets and several nations' steamship services. The main sources have been the sailing data of mail-carrying ships and correspondence of several merchant houses in England. As the world's main trade routes had their specific historical backgrounds with different businesses, interests and needs, the systems for information transmission did not develop similarly or simultaneously. It was a process lasting several decades, initiated by the idea of organizing sailings in a regular line system. The evolution proceeded generally as follows: originally there was a more or less irregular system, then a regular system and finally a more frequent regular system of mail services. The trend was from sail to steam, but both these means of communication improved following the same scheme. Faster sailings alone did not radically improve the number of consecutive information circles per year, if the communication was not frequent enough. Neither did improved frequency advance the information circulation if the trip was very long or if the sailings were overlapping instead of complementing each other. The speed of information transmission could be improved by speeding up the voyage itself (technological improvements, minimizing the waiting time at ports of call, etc.) but especially by organizing sailings so that the recipients had the possibility to reply to arriving mails without unnecessary delay. It took two to three decades before the mail-carrying shipping companies were able to organize their sailings in an optimal way. Strategic shortcuts over isthmuses (e.g. Panama, Suez) together with the cooperation between steamships and railways enabled the most effective improvements in global communications before the introduction of the telegraph.

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The (+)-enantiomer of the polyphenolic binaphthyl gossypol, has been shown to be a useful CD probe of interactions with human and bovine serum albumin. (+)-Gossypol binds to albumin with same affinity as recemic (±)-gossypol, as shown by fluorescence quenching, and also displaces bilirubin from its albumin binding site. The CD characteristics of bound gossypol are different in the case of the two proteins.

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A fast iterative scheme based on the Newton method is described for finding the reciprocal of a finite segment p-adic numbers (Hensel code). The rate of generation of the reciprocal digits per step can be made quadratic or higher order by a proper choice of the starting value and the iterating function. The extension of this method to find the inverse transform of the Hensel code of a rational polynomial over a finite field is also indicated.

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In this work, we theoretically examine recent pump/probe photoemission experiments on the strongly correlated charge-density-wave insulator TaS2.We describe the general nonequilibrium many-body formulation of time-resolved photoemission in the sudden approximation, and then solve the problem using dynamical mean-field theory with the numerical renormalization group and a bare density of states calculated from density functional theory including the charge-density-wave distortion of the ion cores and spin-orbit coupling. We find a number of interesting results: (i) the bare band structure actually has more dispersion in the perpendicular direction than in the two-dimensional planes; (ii) the DMFT approach can produce upper and lower Hubbard bands that resemble those in the experiment, but the upper bands will overlap in energy with other higher energy bands; (iii) the effect of the finite width of the probe pulse is minimal on the shape of the photoemission spectra; and (iv) the quasiequilibrium approximation does not fully describe the behavior in this system.

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The resistivity of two types of lithium fast-ion conductors, Li16-2xZnx(GeO4)4 (x=1,2) and Li3+xGexV1-xO4 (x=0.25,0.6,0.72), showed pronounced maxima as a function of pressure. For the first type, ln(ρ / ρ0) peaked at values of 0.12 (x=1) and 0.35 (x=2) near 20 kbar and decreased thereafter up to 80 kbar. Thermal activation energies and prefactors also showed corresponding maxima. For the second type, ln(ρ / ρ0) increased to 3-4 between 20 and 32 kbar. Near 80 kbar, ρ decreased (for x=0.25) by a factor of 250. The results are interpreted in terms of negative activation volumes.

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Religion without religion. The challenge of radical postmodern philosophy of religion. The aim of this study is to examine the central ideas of Mark C. Taylor, Don Cupitt, and Grace Jantzen on the subject of the philosophy of religion. The method is a qualitative, systematic analysis of the works of the aforementioned philosophers. The purpose is to present, analyze, identify, find connections, and to gain an understanding of the original texts. This thesis shows that radical postmodern religion is “religion without religion”. God is “dead” and the concept of God is seen as “writing”, an ideal, a relationship of meanings or a language. In ethics, there are no objective values or principles. People must create their own morality. Reality is each person´s concept of reality. Language is universal in that language and reality cannot be considered separately. The human subject is contingent and formed in the linguistic and social context. According to postmodern feminism, the ideas that men present as facts are often degrading to women, distort reality and support the power of men. For this reason, we should create a new kind of philosophy of religion and a new language that takes women into consideration. Finally, we will study some philosophers, who have used postmodern ideas in a more moderate manner. In this way, we will look for a balanced solution between modernism and postmodernism. This study shows that the postmodern idea of religion is very different from classical Christianity. Ethics becomes subjective, anarchistic and nihilistic. Epistemology is relativistic and the human being becomes the measure of all things. Objective reality becomes blurry. Language is seen to be game-like, and it has no relation to reality. The moral responsibility of a subject becomes problematic. Science and rationality come into question without the permanent core provided by our consciousness. Women are not in an epistemologically privileged position. The truth claims by either men or women must each be evaluated one at a time. Many postmodern ideas can successfully be made of use if used in moderate manner.

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There’s a polyester mullet skirt gracing a derrière near you. It’s short at the front, long at the back, and it’s also known as the hi-lo skirt. Like fads that preceded it, the mullet skirt has a short fashion life, and although it will remain potentially wearable for years, it’s likely to soon be heading to the charity shop or to landfill...

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The emperor of our fatherland The changing national identity of the elite and the construction of the Finnish fatherland at the beginning of the autonomy This study addresses the question of changing national identity of the elite at the beginning of the autonomy (1808 1814) in Finland. Russia had conquered Finland from Sweden, but Finland was not incorporated into the Russian Empire. Instead, it was governed as separately administered area, and Finland retained its own (laws of the realm of Sweden) laws. The inclusion in the Russian Empire compelled the elite of Finland to deliberate their national identity; they had to determine whether they remained Swedes or became Finns or Russians. The elite chose to become Finns, which may seem obvious from the nowadays perspective, but it cannot be taken for granted that the Swedish speaking and noble elite converted their local Finnish identity into a new national identity. The basis of this study is constructive in a sense that identity is not seen as stable and constant. Theoretical background lies on Stuart Hall s writings on national identity, which offer good practical methods to study national identity. According to Hall identity is based mainly on difference , difference to others . In practice this means how elite began to define themselves in contrast to Swedes and Russians. The Finnish national identity was constructed in contrast to Swedes due to the political reasons. In order to avoid Russians suspicions Finns had to diverge from Sweden. Sweden had also gone trough coup d état, which was disliked by the elite of Finland. However, the attitudes of the elite towards Sweden remained somewhat ambiguous. Even if it was politically and rationally thinking wisest to draw away from Sweden, emotionally it was difficult. Russia, on the other hand, had been for centuries the archenemy of the Finns as well as all the Swedes. The fear of the Russians was mainly imaginary. Russians were seen as cruel barbarians who hated and resented Finns. The Finnish national identity was constructed above all in contrast to the Russians, for the difference to Russia was seen as a precondition for the existence of Finland. Respectively, the new position of Finland also required approaching towards Russia, which was in its nature very pragmatic. The elite contrived to get rid off its prejudice against Russians on intellectual level, but not on emotional level. At the beginning of the autonomy the primary loyalty of the elite was directed into the Finnish fatherland and its habitants. This was a radical ideological change, because traditionally the loyalty of the elite had focused on monarch and monarch s realm. However, the role of Alexander I was crucial. According to the elite the emperor had granted them a new fatherland. The former native country (Finland) was seen as a new fatherland instead of Sweden. The loyalty of the elite to the emperor generated from the reciprocal gratitude; Alexander I had treated their native country so mercifully. The elite felt strong personal responsibility for Finland s existence. The elite believed that the future of Finland rested on their shoulders. Alexander I had given them fatherland, but it was in the hands of the elite to construct the Finnish state and national spirit. The study of the Finnish national identity brings forth also that the national identity was constructed by emphasizing Finns civic rights. The civic rights were essential part of the construction of the Finnish national identity, for the difference between Finns and Russians was based on Finns own laws and privileges, which the emperor of the Russia had ensured.

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The emission from neutral hydrogen (HI) clouds in the post-reionization era (z <= 6), too faint to be individually detected, is present as a diffuse background in all low frequency radio observations below 1420MHz. The angular and frequency fluctuations of this radiation (similar to 1 mK) are an important future probe of the large-scale structures in the Universe. We show that such observations are a very effective probe of the background cosmological model and the perturbed Universe. In our study we focus on the possibility of determining the redshift-space distortion parameter beta, coordinate distance r(nu), and its derivative with redshift r(nu)('). Using reasonable estimates for the observational uncertainties and configurations representative of the ongoing and upcoming radio interferometers, we predict parameter estimation at a precision comparable with supernova Ia observations and galaxy redshift surveys, across a wide range in redshift that is only partially accessed by other probes. Future HI observations of the post-reionization era present a new technique, complementing several existing ones, to probe the expansion history and to elucidate the nature of the dark energy.

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The integration of technology in care is core business in nursing and this role requires that we must understand and use technology informed by evidence that goes much deeper and broader than actions and behaviours. We need to delve more deeply into its complexity because there is nothing minor or insignificant about technology as a major influence in healthcare outcomes and experiences. Evidence is needed that addresses technology and nursing from perspectives that examine the effects of technology, especially related to increasing demands for efficiency, the relationship of technology to nursing and caring, and a range of philosophical questions associated with empowering people in their healthcare choices. Specifically, there is a need to confront in practice the ways technique influences care. Technique is the creation of a kind of thinking that is necessary for contemporary healthcare technology to develop and be applied in an efficient and rational manner. Technique is not an entity or specific thing, but rather a way of thinking that seeks to shape and organize nursing activity, and manage efficiently individual difference(s) in care. It emphasizes predetermined causal relationships, conformity, and sameness of product, process, and thought. In response is needed a radical vision of nursing that attempts in a real sense to ensure we meet the needs of individuals and their community. Activism and advocacy are needed, and a willingness to create a certain detachment from the imperatives that technique demands. It is argued that our responsibility as nurses is to respond in practice to the errors, advantages, difficulties, and temptations of technology for the benefit of those who most need our assistance and care.