Free Vibration of Thermally Pre/Post-Buckled Circular Thin Plates Embedded with Shape Memory Alloy Fibers

Axisymmetric deformations of a uniformly heated pre-buckled and post-buckled thin circular plate reinforced with shape memory alloy (SMA) fibers placed in the radial direction only are studied. Effects of von Kármán's nonlinearities are incorporated in the problem formulation. The matrix is assumed to be linear thermoelastic and the thermo-mechanical response of the SMA is modeled by one-dimensional constitutive relation. By assuming that plate's deflections can be additively decomposed into three parts, namely radial displacements of a pre-buckled plate, radial and lateral displacements during post-buckling deformations, and infinitesimal radial and lateral displacements during vibration of a post-buckled plate, boundary-value problems for determining these displacements for plate edges either simply supported or clamped have been formulated. The coupled nonlinear differential equations have been numerically solved by the shooting method that has been verified by good agreement between the presently computed results with those available in the literature. The dependence of the first three frequencies upon the temperature rise, for both pre-buckled and post-buckled plates, has been delineated. Characteristic curves relating the frequency with the temperature rise for different values of the volume fraction and the pre-strain in the SMA fibers are exhibited. It is found that reinforcement of an aluminum plate with SMA fibers changes plate's natural frequencies and enhances its resistance to buckling due to temperature rise.     

Stereospecific formation of a ternary complex of (S)-α,β-fluoromethylene-dATP with DNA pol β

The influence of water: crystallization of (R/S)-α,β-CHF-dATP with the preorganized pol β-DNA complex shows that (S)-α,β-CHF-dATP is preferentially bound to the active site with the C=F fluorine proximal to a structural water bound to Asp276.     

Toward multiple catheters detection in fluoroscopic image guided interventions

Catheters are routinely inserted via vessels to cavities of the heart during fluoroscopic image guided interventions for electrophysiology (EP) procedures such as ablation. During such interventions, the catheter undergoes nonrigid deformation due to physician interaction, patient's breathing, and cardiac motions. EP clinical applications can benefit from fast and accurate automatic catheter tracking in the fluoroscopic images. The typical low quality in fluoroscopic images and the presence of other medical instruments in the scene make the automatic detection and tracking of catheters in clinical environments very challenging. Toward the development of such an application, a robust and efficient method for detecting and tracking the catheter sheath is developed. The proposed approach exploits the clinical setup knowledge to constrain the search space while boosting both tracking speed and accuracy, and is based on a computationally efficient framework to trace the sheath and simultaneously detect one or multiple catheter tips. The algorithm is based on a modification of the fast marching weighted distance computation that efficiently calculates, on the fly, important geodesic properties in relevant regions of the image. This is followed by a cascade classifier for detecting the catheter tips. The proposed technique is validated on 1107 fluoroscopic images acquired on multiple patients across four different clinics, achieving multiple catheter tracking at a rate of 10 images/s with a very low false positive rate of 1.06.     

In Situ Characterization of Lattice Structure Evolution during Phase Transformation of Zr‐2.5Nb

The α–β phase transformation behavior of Zr‐2.5Nb (in mass%) has been characterized in real time during an in situ neutron diffraction experiment. The Zr‐2.5Nb material in the current study consists, at room temperature, of α‐Zr phase (hcp) and two β phases (bcc), a Nb rich β‐Nb phase and retained, Zr rich, β‐Zr(Nb) phase. It is suggested that this is related to a quench off the equilibrium solubility of Nb atoms in the Zr bcc unit cells. Vegard's law combined with thermal expansion is applied to calculate the composition of the β‐phase, which is compared with the phase diagram, revealing the system's kinetic behavior for approaching equilibrium.     

Carbohydrate composition of developing grains of the high-lysine barley mutant (notch-2) and its parent (NP 113)

Barley variety NP 113 had higher accumulations of dry matter (DM) and starch than its high-lysine mutant, Notch-2, during grain development. Protein, amylose and amylopectin content per grain were lower in Notch-2 than NP 113. Reducing sugars, free glucose, total fructose and non-reducing sugars were 1.57–3.15-fold in Notch-2 grain as compared with NP 113 grain. DM, protein, starch, amylose and amylopectin per grain increased during grain development. Soluble sugar contents per grain were maximum at 24 days after anthesis. Lower DM accumulation in the Notch-2 mutant as compared with its parent, NP 113, is due to lower starch deposition. Further, the limitation of starch synthesis in the Notch-2 mutant is not due to any limitation in the supply of soluble sugar precursors.     

Evaluating copper lysine and copper sulfate sources for heifers

The effects of feeding different sources and quantities of Cu to heifers were evaluated in a 211-d experiment. Forty crossbred predominantly Brahman x Hereford heifers averaging 13.5 mo of age and 301 kg were initially depleted of Cu. The depletion diet was fed for 70 d and consisted of low Cu and high antagonist minerals, Fe, S, and Mo at 1000 mg/kg, 0.5%, and 5 mg/kg (dry basis), respectively. On d 71, heifers continued to receive the antagonistic minerals and were allotted equally to five Cu treatments: 1) control, no additional Cu source; 2) 8 mg of Cu/kg from CuSO4; 3) 16 mg of Cu/kg from CuSO4; 4) 8 mg of Cu/kg from Cu lysine; and 5) 16 mg of Cu/kg from Cu lysine. When no notable change in concentration of Cu in the liver was observed, d 169, a second diet was formulated. The heifers were fed the same Cu treatments, but S and Mo were removed and Fe was lowered to 50 mg/kg. This diet was then fed for the final 42 d of the experiment. In addition to performance, concentrations of Cu, Fe, and Zn in the plasma and liver, plasma ceruloplasmin, hemoglobin, superoxide dismutase (SOD) activity of neutrophils and lymphocytes, and a cell mediated immune response (phytohemagglutinin-P, PHA) were measured. Heifers in this study had increased growth over time, but there were no treatment differences for growth and average daily gain. Liver and plasma Cu concentrations were not greatly influenced by different supplemental Cu sources. However, compared with other treatments, Cu lysine (16 mg/kg) increased liver Cu in cattle that were deficient and tended to increase plasma Cu in animals that were marginally deficient in Cu. Iron concentrations decreased over time in liver and plasma, but there was no difference in Fe and Zn concentrations in liver and plasma among treatments. Differences in ceruloplasmin and hemoglobin concentrations were significant over time but not among treatments. The SOD activity in neutrophils did not change over time, but SOD activity of lymphocytes increased over time. For the PHA immune response test, there was no effect of time or a time by treatment interaction. These data suggest that all Cu sources were available, but Cu at 16 mg/kg from Cu lysine was more beneficial than were other sources and particularly for heifers with low Cu status.     

Helical Flow of a Sutterby Model Fluid

The problem of helical flow of a Sutterby model fluid has been analyzed numerically using a finite difference technique. Sutterby model fluid is one of the most important non-Newtonian fluids representing constitutive equations for high polymer aqueous solutions of CMC, HEC, and MC, and hence the problem is of practical significance. Computations have been made for the case when the inner cylinder rotates about the common axis with constant angular velocity and the outer cylinder is at rest, while a constant pressure gradient is acting on the axis of rotation. The dimensionless velocity profiles, volumetric flow rate, torque, and pressure distribution have been calculated for various values of the model parameters and the radius ratio.     

A wavelet collocation method for the static analysis of sandwich plates using a layerwise theory

A study of bending deformations of sandwich plates using a layerwise theory of laminated or sandwich plates is presented. The analysis is based on a wavelet collocation technique to produce highly accurate results. Numerical results for symmetric laminated composite and sandwich plates are presented and discussed.     

Electrical characterization of LiTaO<Subscript>3</Subscript>:P(VDF–TrFE) composites

Composites of pyroelectric ceramics and polymers are very important as their unique features and properties can be easily tailored for various specific applications. Lithium tantalatum oxide (LiTaO₃, LT), the pyroelectric ceramic powder has been incorporated into a polyvinylidene fluoride–trifluoroethylene [P(VDF–TrFE) 70/30 mol%] copolymer matrix to form 0–3 composites. The composite films were prepared using ‘solvent casting’ (SC) method to disperse the ceramic powder homogeneously in the P(VDF–TrFE) copolymer matrix with various wt% of LT powder. In order to derive high pyroelectric performance, the samples were poled. Electric properties, such as the dielectric constant, dielectric loss, and pyroelectric coefficient, have been measured as a function of temperature and frequency. In addition, material figures-of-merit, very important factors for assessing many sensor applications have also been calculated. The results show that the fabricated lead free lithium tantalite: P(VDF–TrFE) composite materials have a good potential for pyroelectric infrared sensor applications.