Elucidation of 3D-to-2D transformation by magnetization studies for Hc in Bi2Sr2CaCu2O8

New magnetization results (for Hc) on a single crystal of Bi2212 elucidating the transition from a one-component to a two- component response across the 3D-to-2D transformation are reported. The two-component response is identified to emanate from the 2D planes and interplanar links. The magnetization response above the transformation temperature T_s and very close to T_c is found to be irreversible in contrast to the reversible behavior so far believed in. A new phase diagram for the mixed state of layered superconductors near T_c is proposed.     

Cross-flow induced vibrations in a tube bank—Turbulent buffeting and fluid elastic instability

Experimental results are reported for a wind tunnel study of cross-flow induced vibrations in a tube bank. The rotated triangular array had a pitch ratio of 1·375 and consisted of 19 flexibly mounted tubes surrounded by 116 rigid, removable tubes. The natural frequency and damping of the flexibly mounted tubes could be carefully controlled. Details of the experimental facility and the vortex shedding behaviour of the tube bank were reported in the first of these two companion papers. The turbulent buffeting and fluid elastic response are treated in this second paper. The effects on the fluid elastic threshold of the motion of surrounding tubes, damping and number of upstream rows of tubes are discussed.     

The effect of the order of Gauss quadrature on the free vibrations of plates in fluid

In this paper two types of approach are used for the dynamic analysis of plates in fluid. The first approach is based on the classical thin plate theory. The second approach is based on the modified thin plate theory in which transverse shear has been included. The analysis also includes the compressibility effect of the fluid. The results obtained with the second approach are closer to the practical results than those obtained by any other approach provided both the shear and interaction matrices are evaluated with low-order Gauss quadrature. It is also shown that in problems of infinite regions the use of infinite elements coupled with finite elements not only gives accurate results but also economises on computation time and storage.     

Detection of the difference between two images: An improved method

The method for the detection of the difference between two images, proposed by the authors, can be modified to improve the signal/noise ratio. An amplitude distribution proportional to cos²? is obtained in the Fourier plane using three exposures in the ratio 1 : 2 : 1. In the neighbourhood of ? = Π/2 the gradient of this distribution is one order of magnitude inferior to that of cos? obtained with two equal exposures. Consequently a wider slit can be used as a filter. A further improvement can be obtained if the number of exposures is increased.     

Genetically encoded pH sensor for tracking surface proteins through endocytosis

Traffic cam: a tandem dye prepared from a FRET acceptor and a fluorogenic donor functions as a cell surface ratiometric pH indicator, which upon internalization serves to follow protein trafficking during endocytosis. This sensor was used to analyze agonist-dependent internalization of β(2)-adrenergic receptors. It was also used as a surrogate antigen to reveal direct surface-to-endosome antigen transfer between dendritic cells (not shown).     

A new lithium alkoxide accelerated diastereoselective cyanation of ketones

[reaction: see text] A remarkably general lithium heteroatom assisted TMSCN or TBSCN addition to aldehydes and ketones has been discovered. The process provides excellent selectivities and high rates. Conformationally constrained ketones such as camphor, fenchone, and nopinone give excellent diastereoselectivities with TMSCN. Reduction of 2 provided diastereopure amino alcohol 3 in good yield. alpha- and beta-Methyl cyclohexanones with TBSCN-LiOR afford high diastereoselectivities and yields.     

Anomalous magnetic hysteresis loops and smallH c1 values in highT c superconductors

We have studied the hysteresis loops of RBa₂Cu₃O₇ (R=Gd, Ho and Y) and detected anomalies in some of them. The observed anomalies support a recent prediction by Ravi Kumar and Chaddah based on an extension of Bean’s model. The anomalies indicate lowH _c1 values and we have confirmed this by studying the onset of low-field hysteresis in less than 10 Oe at 77 K for these highT _c superconductors.