977 resultados para Phi Delta Theta Fraternity.


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2 scans - 1of2 = entire page, 2of2 = Chi Phi members only

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3 scans - 1of3 = entire page, 2of3 = Fraternity House, 3of3 = Chi Phi members only

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By using the lower bound limit analysis in conjunction with finite elements and linear programming, the bearing capacity factors due to cohesion, surcharge and unit weight, respectively, have been computed for a circular footing with different values of phi. The recent axisymmetric formulation proposed by the authors under phi = 0 condition, which is based on the concept that the magnitude of the hoop stress (sigma(theta)) remains closer to the least compressive normal stress (sigma(3)), is extended for a general c-phi soil. The computational results are found to compare quite well with the available numerical results from literature. It is expected that the study will be useful for solving various axisymmetric geotechnical stability problems. Copyright (C) 2010 John Wiley & Sons, Ltd.

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alpha,beta-Dehydrophenylalanine residues constrain the peptide backbone to beta-bend conformation. A pentapeptide containing four consecutive (Delta Phe) residues has been synthesised and crystallised. The peptide Boc-LAla-Delta Phe-Delta Phe-Delta Phe-Delta Phe-NHMe (C45H46N6O7, MW = 782.86) was crystallised from an acetonitrile/methanol mixture. The crystal belongs to the orthorhombic space group P2(1)2(1)2(1) With a = 19.455(6), b = 20.912(9), c = 11.455(4) Angstrom and Z = 4. The X-ray (MoKalpha, lambda = 0.7107 Angstrom) intensity data were collected using the Rigaku-AFC7 diffractrometer. The crystal structure was determined by direct methods and refined using the least-squares technique, R = 8.41% for 1827 reflections with \F-o\ > 4 sigma\F-o\. The molecule contains the largest stretch of consecutive dehydrophenylalanine residues whose crystal structure has been determined so far. The peptide adopts left-handed 3(10)-helical conformation despite the presence of LAla at the N-terminus. The mean phi, psi values, averaged across the last four residues are 56.8 degrees and 17.5 degrees, respectively. There are four 4-->1 intramolecular hydrogen bonds, characteristic of the 3(10)-helix. In the crystal each molecule interacts with four crystallographically symmetric molecules with one hydrogen bond each.

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An N-alpha-protected model pentapeptide containing two consecutive Delta Phe residues, Boc-Leu-Delta Phe-Delta Phe-Ala-Phe-NHMe, has been synthesized by solution methods and fully characterized. H-1-nmr studies provided evidence for the occurrence of a significant population of a conformer having three consecutive, intramolecularly II-bonded beta-bends in solution. The solid state structure has been determined by x-ray diffraction methods. The crystals grown from aqueous methanol are orthorhombic, space group P2(1)2(1)2(1),, a = 11.503(2), b = 16.554(2), c = 22.107(3) Angstrom, V = 4209(1) Angstrom,(3) and Z = 4. The x-ray data were collected on a CAD4 diffractometer using CuKalpha radiation (lambda = 1.5418 Angstrom). The structure was determined using direct methods and refined by full-matrix least-squares procedure. The R factor is 5.3%. The molecule is characterized by a right handed 3(10)-helical conformation ((phi) = -68.2 degrees (psi) = -26.3 degrees), which is made up of two consecutive type III beta-bends and one type I beta-bend. In the solid state the helical molecules are aligned head-to-tail, thus forming long rod like structures. A comparison with other peptide structures containing consecutive Delta Phe residues is also provided. The present study confirms that the -Delta Phe-Delta Phe-sequence can be accommodated in helical structures. (C) 1997 John Wiley & Sons, Inc.

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From St15 micro-carbon deep drawing steel sheets, two sets of samples with (r) over bar variant and Deltar constant, and (r) over bar constant and Deltar variant, were selected to carry out texture measurement and ODF analysis. A description of the texture characteristics and an investigation on the effect of the main textures on the (r) over bar and Deltar values were given. The results show that in the tested steel sheets no desired gamma < 111 > parallel to ND orientation line appears but gamma' orientation line located at <()over bar>=0-90 degrees, theta =19 degrees and phi =45 degrees, and L orientation line located around gamma < 111 > parallel to ND orientation line which spirally rotates from Psi =0 degrees, theta =54.7 degrees and phi =62.7 degrees to Psi =90 degrees, theta =40 degrees and phi =45 degrees occur. Among them, the L orientation line has a main influence on the (r) over bar value and the stronger the texture density, the higher the (r) over bar value is, but is somewhat detrimental to the Deltar value; at the same time, the gamma' orientation line has a major effect on the Deltar value in an opposite way, but is somewhat deteriorative to the (r) over bar value. A strong L orientation line superposed by a relatively strong gamma' orientation line may produce fine (r) over bar and Deltar values.

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We have studied the normal and superconducting transport properties of Bi(1.65)Pb(0.35)Sr(2)Ca(2)Cu(3)O(10+delta) (Bi-2223) ceramic samples. Four samples, from the same batch, were prepared by the solid-state reaction method and pressed uniaxially at different compacting pressures, ranging from 90 to 250 MPa before the last heat treatment. From the temperature dependence of the electrical resistivity, combined with current conduction models for cuprates, we were able to separate contributions arising from both the grain misalignment and microstructural defects. The behavior of the critical current density as a function of temperature at zero applied magnetic field, J (c) (T), was fitted to the relationship J (c) (T)ae(1-T/T (c) ) (n) , with na parts per thousand 2 in all samples. We have also investigated the behavior of the product J (c) rho (sr) , where rho (sr) is the specific resistance of the grain-boundary. The results were interpreted by considering the relation between these parameters and the grain-boundary angle, theta, with increasing the uniaxial compacting pressure. We have found that the above type of mechanical deformation improves the alignment of the grains. Consequently the samples exhibit an enhance in the intergranular properties, resulting in a decrease of the specific resistance of the grain-boundary and an increase in the critical current density.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The optimized delta-expansion is a nonperturbative approach for field theoretic models which combines the techniques of perturbation theory and the variational principle. This technique is discussed in the lambda phi(4) model and then implemented in the Walecka model for the equation of state of nuclear matter. The results obtained with the delta expansion are compared with those obtained with the traditional mean field, relativistic Hartree and Hartree-Fock approximations.

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A knowledge of rock stress is fundamental for improving our understanding of oceanic crustal mechanisms and lithospheric dynamic processes. However, direct measurements of stress in the deep oceans, and in particular stress magnitudes, have proved to be technically difficult. Anelastic strain recovery measurements were conducted on 15 basalt core samples from Sites 765 and 766 during Leg 123. Three sets of experiments were performed: anelastic strain recovery monitoring, dynamic elastic property measurements, and thermal azimuthal anisotropy observations. In addition, a range of other tests and observations were recorded to characterize each of the samples. One common feature of the experimental results and observations is that apparently no consistent orientation trend exists, either between the different measurements on each core sample or between the same sets of measurements on the various core samples. However, some evidence of correspondence between velocity anisotropy and anelastic strain recovery exists, but this is not consistent for all the core samples investigated. Thermal azimuthal anisotropy observations, although showing no conclusive correlations with the other results, were of significant interest in that they clearly exhibited anisotropic behavior. The apparent reproducibility of this behavior may point toward the possibility of rocks that retain a "memory" of their stress history, which could be exploited to derive stress orientations from archived core. Anelastic strain recovery is a relatively new technique. Because use of the method has extended to a wider range of rock types, the literature has begun to include examples of rocks that contracted with time. Strong circumstantial evidence exists to suggest that core-sample contractions result from the slow diffusion of pore fluids from a preexisting microcrack structure that permits the rock to deflate at a greater rate than the expansion caused by anelastic strain recovery. Both expansions and contractions of the Leg 123 cores were observed. The basalt cores have clearly been intersected by an abundance of preexisting fractures, some of which pass right through the samples, but many are intercepted or terminate within the rock matrix. Thus, the behavior of the core samples will be influenced not only by the properties of the rock matrix between the fractures, but also by how these macro- and micro-scale fractures mutually interact. The strain-recovery curves recorded during Leg 123 for each of the 15 basalt core samples may reflect the result of two competing time dependent processes: anelastic strain recovery and pore pressure recovery. Were these the only two processes to influence the gauge responses, then one might expect that given the additional information required, established theoretical models might be used to determine consistent stress orientations and reliable stress magnitudes. However, superimposed upon these competing processes is their respective interaction with the preexisting fractures that intersect each core. Evidence from our experiments and observations suggests that these fractures have a dominating influence on the characteristics of the recovery curves and that their effects are complex.