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81.
82.
83.
Azevedo Celsina N. Gonçalves Victor P. Moreira Bruno D. 《The European Physical Journal A - Hadrons and Nuclei》2023,59(2):1-13
The European Physical Journal A - We give an overview of the special challenges regarding target development and production for accelerator-based heavy and superheavy-nuclei experiments in the past... 相似文献
84.
J. C. P. Pina A. M. Dias P. F. P. de Matos P. M. G. P. Moreira P. M. S. T. de Castro 《Experimental Mechanics》2005,45(1):83-88
In this paper we present the methods of determination and the stress obtained at the periphery of a cold expanded hole in
a 2024-T3 Alclad aluminum alloy sheet. The measurements in the aluminum clad were performed by the sin2Ψ method, taking experimental precautions to deal with the texture effects. In the core aluminum a special method had to be
implemented to determine the stress values in a direction not accessible to the X-ray diffraction. The strains were measured
in sample orientations selected according to the texture characteristics and stress factorsF
ij
were used to calculate the stress tensor. TheF
ij
values were determined assuming a quasi-isotropic material behavior, after concluding that the stress results were not significantly
affected by factors calculated for textured material. The residual stress profile, both in the clad and in the sheet, shows
a nearly axisymmetric stress state. Compressive stresses were observed near the periphery of the hole, with values that are
higher on the exit than on the entrance face. Residual stresses were also higher in the hoop direction than in the radial
direction. They decreased with the radial distance to the hole and affected the previous stress state over a distance of 6
mm. The plastic deformation induced by the cold expansion is well evidenced by the FWHM values, which in the affected zone
decrease with increasing distance from the hole edge. 相似文献
85.
86.
Roberto Laridondo Lui Daniel Rodrigues Blanco Vladimir Pavan Margarido Orlando Moreira Filho 《Micron (Oxford, England : 1993)》2009,40(5-6):552-559
B chromosomes are considered additional and non-essential; they likely originate from A chromosomes and follow a distinct evolution. In fish, approximately half of the Neotropical species with B chromosomes are Characiformes and 35% are Siluriformes. There has been no report of B chromosomes in Auchenipteridae until this moment. B chromosomes found in a population of Parauchenipterus galeatus from the São Francisco River basin in the state of Minas Gerais (Brazil) were small, metacentric, totally heterochromatic and exhibited intra-individual and inter-individual variation. The diploid number was 58 chromosomes (22 metacentric, 16 submetacentric, 12 subtelocentric and 8 acrocentric). The nucleolar organizing regions were simple and the heterochromatin intercalated in the ribosomal sites, characterized by CMA3 and DAPI fluorochromes, was of a GC-rich constitution. The 5S rDNA genes were located in an intercalary position in only one chromosome pair. An hypothesis about the origin of the B chromosomes in P. galeatus and a review on B chromosomes in catfish are also presented in this study. 相似文献
87.
G. Franzò A. Irrera E.C. Moreira M. Miritello F. Iacona D. Sanfilippo G. Di Stefano P.G. Fallica F. Priolo 《Applied Physics A: Materials Science & Processing》2002,74(1):1-5
We have studied the structural, electrical and optical properties of MOS devices, where the dielectric layer consists of a
substoichiometric SiOx (x<2) thin film deposited by plasma-enhanced chemical vapor deposition. After deposition the samples were annealed at high
temperature (>1000 °C) to induce the separation of the Si and the SiO2 phases with the formation of Si nanocrystals embedded in the insulating matrix. We observed at room temperature a quite intense
electroluminescence (EL) signal with a peak at ∼850 nm. The EL peak position is very similar to that observed in photoluminescence
in the very same device, demonstrating that the observed EL is due to electron–hole recombination in the Si nanocrystals and
not to defects. The effects of the Si concentration in the SiOx layer and of the annealing temperature on the electrical and optical properties of these devices are also reported and discussed.
In particular, it is shown that by increasing the Si content in the SiOx layer the operating voltage of the device decreases and the total efficiency of emission increases. These data are reported
and their implications discussed.
Received: 31 August 2001 / Accepted: 3 September 2001 / Published online: 17 October 2001 相似文献
88.
89.
The human leukocyte elastase (HLE), a neutrophil serine protease of the chymotrypsin superfamily, is a major therapeutic target for a number of inflammatory diseases, such as chronic obstructive pulmonary disease (COPD). In this work, we present a comparative explicit water molecular dynamics (MD) study on the free and inhibitor-bound HLE. Knowledge of the flexibility and conformational changes induced by this irreversible inhibitor, whether in a prebound stage or covalently bound at the enzyme binding site, encases fundamental biological interest and is particularly relevant to ongoing structure-based drug design studies. Our results suggest that HLE operates by an induced-fit mechanism with direct intervention of a surface loop which is open toward the solvent in the free enzyme and closed while in the presence of the ligand. MM-PBSA free energy calculations furthermore elucidate the energetic contributions to the distinct conformations adopted by this loop. Additionally, a survey of the major contributions to the inhibitor binding free energies was attained. Our findings enforce the need to account for HLE flexibility, whether through the use of MD-generated ensembles of HLE conformations as targets for molecular docking or via sophisticated flexible-docking algorithms. We anticipate that inclusion of the observed HLE dynamic behavior into future drug design methodologies will have a relevant impact in the development of novel, more efficient, inhibitors. 相似文献
90.
In a paper from 1954 Marstrand proved that if K⊂R2 has a Hausdorff dimension greater than 1, then its one-dimensional projection has a positive Lebesgue measure for almost all directions. In this article, we give a combinatorial proof of this theorem when K is the product of regular Cantor sets of class C1+α, α>0, for which the sum of their Hausdorff dimension is greater than 1. 相似文献