988 resultados para Solid forms


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Existence of a periodic progressive wave solution to the nonlinear boundary value problem for Rayleigh surface waves of finite amplitude is demonstrated using an extension of the method of strained coordinates. The solution, obtained as a second-order perturbation of the linearized monochromatic Rayleigh wave solution, contains harmonics of all orders of the fundamental frequency. It is shown that the higher harmonic content of the wave increases with amplitude, but the slope of the waveform remains finite so long as the amplitude is less than a critical value.

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Conformational preferences of thiocarbonohydrazide (H2NNHCSNHNH2) in its basic and N,N′-diprotonated forms are examined by calculating the barrier to internal rotation around the C---N bonds, using the theoretical LCAO—MO (ab initio and semiempirical CNDO and EHT) methods. The calculated and experimental results are compared with each other and also with values for N,N′-dimethylthiourea which is isoelectronic with thiocarbonohydrazide. The suitability of these methods for studying rotational isomerism seems suspect when lone pair interactions are present.

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A new technique has been devised to achieve a steady-state polarisation of a stationary electrode with a helical shaft rotating coaxial to it. A simplified theory for the convective hydrodynamics prevalent under these conditions has been formulated. Experimental data are presented to verify the steady-state character of the current-potential curves and the predicted dependence of the limiting current on the rotation speed of the rotor, the bulk concentration of the depolariser and the viscosity of the solution. Promising features of the multiple-segment electrodes concentric to a central disc electrode are pointed out.

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We have prepared, characterized and investigated a new PEG-2000 based solid polymer electrolyte (PEG) x NH4I. Ionic conductivity measurements have been made as a function of salt concentration as well as temperature in the range 265–330 K. Selected compositions of the electrolyte were exposed to a beam of 8 MeV electrons to an accumulated dose of 10 kGy to study the effect on ionic conductivity. The electrolyte samples were also quenched at liquid nitrogen temperature and conductivity measurements were made. The ionic conductivity at room temperature exhibits a characteristic double peak for the composition x = 20 and 70. Both electron beam irradiation and quenching at low temperature have resulted in an increase in conductivity by 1–2 orders of magnitude. The enhancement of conductivity upon irradiation and quenching is interpreted as due to an increase in amorphous region and decrease in crystallinity of the electrolyte. DSC and proton NMR measurements also support this conclusion.

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"The Art of Sympathy: Forms of Moral and Emotional Persuasion" in Fiction is an interdisciplinary study that looks closely at the ways that stories evoke sympathy, and the significance of this emotion for the development of moral attitudes and awareness. By linking readers' emotional responses to fiction with the potential impact of such responses on "the moral imagination," the study builds on empirical research conducted by literary scholars and psychologists into the emotional effects of reading fiction, as well as social psychological research into the connections between empathy/sympathy and moral development. I first investigate the dynamics of readers beliefs regarding characters in fictional narratives, and the nature of the emotions that they may experience as a result of those beliefs. The analysis demonstrates that there are important similarities between real emotions and emotions generated by fiction. Recognizing these similarities, I claim, can help us to conceptualize the nature of sympathetic responses to fictional characters. Building on these assertions, I then draw on research from social psychology and philosophy to develop a comprehensive definition of sympathy and to clarify the ways in which sympathy operates, both in people s daily lives and in readers sympathetic responses to fictional characters. Having established this definition and delineated its practical implications, I then examine how particular stories, through a variety of narrative techniques, persuade readers to feel sympathy for characters who are unsympathetic in certain ways. In order to verify my claims about the impact of these stories on readers emotions, I also review the results of tests that I conducted with nearly 200 adolescent readers. Through these tests, which were constructed and scored according to methods prevalent in social psychological research, it was determined that a majority of readers felt sympathy for the protagonists in two of the stories included in the study. These results were combined with data from an additional test, a standard measure of empathy and sympathy in the field of social psychology. The cross-tabulation of these results suggests that there was not a strong connection between readers responses and their general tendencies to feel sympathy for others. This finding would appear to support my hypotheses regarding the sympathetic persuasiveness of the stories in question. In light of these results, finally, I consider the potential contribution that fiction can make to adolescent emotional and moral development and the implications of that potential for future language arts curricula in the schools. In particular, I suggest the pedagogical importance of providing adolescents with opportunities to engage with the lives of fictional characters, and especially to experience feelings of sympathy for individuals towards whom they ordinarily might feel aversion.

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We demonstrate ordered array formation of Au nanoparticles by controlled solid-state dewetting of a metal film on stepped alumina substrates. In situ transmission electron microscopy studies reveal that the dewetting process starts with nucleation of ordered dry regions on the substrate. The chemical potential difference between concave and convex surface regions induces anisotropic metal diffusion leading to the formation of nanowires in the valleys. The nanowires fragment due to Rayleigh instability forming arrays of metal nanoparticles on the substrate. The length scale of reconstruction relative to the starting film thickness is an important parameter in controlling the spatial order of the nanoparticles.

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Based on x-ray crystallographic studies, it is shown that crystal chemical factors govern the reversible photodimerization of phenylbutadienes in the solid state.

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The study explores the first appearances of Russian ballet dancers on the stages of northern Europe in 1908 1910, particularly the performances organized by a Finnish impresario, Edvard Fazer, in Helsinki, Stockholm, Copenhagen and Berlin. The company, which consisted of dancers from the Imperial Theatres of St. Petersburg, travelled under the name The Imperial Russian Ballet of St. Petersburg. The Imperial Russian Ballet gave more than seventy performances altogether during its tours of Finland, Sweden, Denmark and central Europe. The synchronic approach of the study covers the various cities as well as genres and thus stretches the rather rigid geographical and genre boundaries of dance historiography. The study also explores the role of the canon in dance history, revealing some of the diversity which underlies the standard canonical interpretation of early twentieth-century Russian ballet by bringing in source material from the archives of northern Europe. Issues like the central position of written documentation, the importance of geographical centres, the emphasis on novelty and reformers and the short and narrow scholarly tradition have affected the formation of the dance history canon in the west, often imposing limits on the historians and narrowing the scope of research. The analysis of the tours concentrates on four themes: virtuosity, character dancing, the idea of the expressive body, and the controversy over ballet and new dance. The debate concerning the old and new within ballet is also touched upon. These issues are discussed in connection with each city, but are stressed differently depending on the local art scene. In Copenhagen, the strong local canon based on August Bournonville s works influenced the Danish criticism of Russian ballet. In Helsinki, Stockholm and Berlin, the lack of a solid local canon made critics and audiences more open to new influences, and ballet was discussed in a much broader cultural context than that provided by the local ballet tradition. The contemporary interest in the more natural, expressive human body, emerging both in theatre and dance, was an international trend that also influenced the way ballet was discussed. Character dancing, now at low ebb, played a central role in the success of the Imperial Russian Ballet, not only because of its exoticism but also because it was considered to echo the kind of performing body represented by new dance forms. By exploring this genre and its dancers, the thesis brings to light artists who are less known in the current dance history canon, but who made considerable careers in their own time.

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An apparatus is described that facilitates the determination of incorporation levels of isotope labelled, gaseous precursors into volatile insect-derived metabolites. Atmospheres of varying gas compositions can be generated by evacuation of a working chamber followed by admission of the required levels of component gases, using a precision, digitised pressure read-out system. Insects such as fruit-flies are located initially in a small introduction chamber, from which migration can occur downwards into the working chamber. The level of incorporation of labelled precursors is continuously assayed by the Solid Phase Micro Extraction (SPME) technique and GC-MS analyses. Experiments with both Bactrocera species (fruit-flies) and a parasitoid wasp, Megarhyssa nortoni nortoni (Cresson) and oxygen-18 labelled dioxygen illustrate the utility of this system. The isotope effects of oxygen-18 on the carbon-13 NMR spectra of 1,7- dioxaspiro[5,5]undecane are also described.

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Initiation and propagation processes in thermally initiated solid-state polymerization of sodiumvacrylate have been studied. The kinetics of initiation, followed with the electron spin resonancev technique, leads to an activation energy E of 28.8 kcal/mol, which is attributed to the formation of dimeric radicals. The activation energy of 16 f 1 kcaVmol obtained for the solid-state polymerization of sodium acrylate by chemical analysis and differential scanning calorimetry has been attributed to the propagation process.

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he Dirac generator formalism for relativistic Hamiltonian dynamics is reviewed along with its extension to constraint formalism. In these theories evolution is with respect to a dynamically defined parameter, and thus time evolution involves an eleventh generator. These formulations evade the No-Interaction Theorem. But the incorporation of separability reopens the question, and together with the World Line Condition leads to a second no-interaction theorem for systems of three or more particles. Proofs are omitted, but the results of recent research in this area is highlighted.

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The role of imperfections in thermal polymerization of acrylamide in the solid state was studied. The polymer yield and the degree of polymerization are highly dependent on the particle size and on the pressure to which the monomer is subjected prior to polymerization reaction. There is an enhancement in the rate of polymerization in air unlike in the case of radiation-induced polymerization. Thermal polymerization of acrylamide in pelletized form results in the formation of water-soluble linear polymer and water-insoluble cross-linked product with the evolution of ammonia. The activation energy (E) values obtained in the present investigation reveal that basically there are two processes taking place, one with E = 34–36 kcal/mole, corresponding to the initiation process, and the other with E = 19 ± 3 kcal/more for the propagation process.

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Dispersions of Al2O3 as well as CeO2 in CaF2 are found to enhance the conductivity of CaF2. Both these systems are biphasic and the electrical conduction in them is purely ionic in nature. At 650 K the increase in the ionic conductivity of the dispersed solid electrolyte system CaF2---Al2O3 is by about two orders of magnitude in relation to the conductivity of the host electrolyte CaF2, whereas for the CaF2---CeO2 system it is about three orders of magnitude. Some aspects of the increase in the ionic conductivities of CaF2---Al2O3 and CaF2---CeO2 electrolytes can be explained by a recent theoretical model. It is proposed that a substantial enhancement in the vacancy concentration of CaF2, brought about by the attraction of F− ions to the surface of Al2O3 (or CeO2), is responsible for the low temperature increase in the ionic conductivity of CaF2.

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The conformational analysis of a protected homodipeptide of 1-aminocyclopentanecarboxylic acid (Acc5) has been carried out. 1H-nmr studies establish a -turn conformation for Boc-Acc5-Acc5-NHMe in chloroform and dimethylsulfoxide solutions involving the methylamide NH in an intramolecular hydrogen bond. Supportive evidence for the formation of an intramolecular hydrogen bond is obtained from ir studies. X-ray diffraction studies reveal a type III -turn conformation in the solid state stabilized by a 4 1 hydrogen bond between the Boc CO and methylamide NH groups. The , values for both Acc5 residues are close to those expected for an ideal 310-helical conformation ( ± 60°, ±30°).