On the luminescence of TlCl+KCl phosphor

The measurements on the luminescence spectra of TlCl+KCl mixed phosphor under low energy cathode rays at 80° K have been presented here. The reflectance as well as excitation spectra of this mixed phosphors have also been studied. The X-ray diffraction studies of the samples along with the optical studies show that the mixed phosphor consists of two phases: (1) KCl:Tl (2) TlCl:K. It has been observed that the emission bands due to thallous chloride are gradually quenched with the increase in potassium chloride content of the phosphor; further, the emission bands supposed to be due to KCl:Tl phosphors gradually appear. Since some of the emission bands obtained with KCl:Tl phosphors at high thallium content are also present in the luminescence spectra of thallous chloride it is suggested that such bands should be attributed to undissociated thallous chloride present in KCl:Tl phosphor. The quenching of thallous chloride emission by the incorporation of potassium chloride in the system has been explained as being due to the absence of stoichiometric excess of thallium in such mixed system. The results also show that the absorption spectra of the mixed system is determined by the minor components KCl:Tl. This indicates that the absorption spectra of KCl:Tl phosphor should not be affected by the presence of undissociated thallous chloride.     

NMR spectral studies. XIV. Carbon-13 nuclear magnetic resonance studies on β-lactams

Carbon-13 NMR spectra of a variety of mono- and bicyclic β-lactams have been measured and the chemical shifts of the ring carbon atoms have been assigned unambiguously. Effects of substituents on the chemical shifts of these carbons are also discussed.     

Transmission through chiral twist defects in anisotropic periodic structures

A long-lived photonic state is observed in measurements of microwave transmission through a helical stack of anisotropic overhead transparencies with various twist defects in the center of the structure. Once account is taken of absorption and of the angular spread of the source, computer simulations of transmission through a polarized localized state are in agreement with measurements. Unlike for isotropic one-dimensional bandgaps, the intensity of the localized mode is not modulated in space on a wavelength scale.     

Quantum communication through an unmodulated spin chain

We propose a scheme for using an unmodulated and unmeasured spin chain as a channel for short distance quantum communications. The state to be transmitted is placed on one spin of the chain and received later on a distant spin with some fidelity. We first obtain simple expressions for the fidelity of quantum state transfer and the amount of entanglement sharable between any two sites of an arbitrary Heisenberg ferromagnet using our scheme. We then apply this to the realizable case of an open ended chain with nearest neighbor interactions. The fidelity of quantum state transfer is obtained as an inverse discrete cosine transform and as a Bessel function series. We find that in a reasonable time, a qubit can be directly transmitted with better than classical fidelity across the full length of chains of up to 80 spins. Moreover, our channel allows distillable entanglement to be shared over arbitrary distances.     

Unwinding of DNA polymerases by the antitumor drug,cis-diamminedichloroplatinum(II)

The helix-turn-helix motifs of the DNA binding domains of human polymerase-alpha and polymerase-kappa are dramatically perturbed upon binding to cisplatin with concomitant release of zinc.     

On initial conditions for a boundary stabilized hybrid Euler-Bernoulli beam

We consider here small flexural vibrations of an Euler-Bernoulli beam with a lumped mass at one end subject to viscous damping force while the other end is free and the system is set to motion with initial displacementy ⁰(x) and initial velocityy ¹ (x). By investigating the evolution of the motion by Laplace transform, it is proved (in dimensionless units of length and time) that

Proposal for measurement of harmonic oscillator berry phase in ion traps

We propose a scheme for measuring the Berry phase in the vibrational degree of freedom of a trapped ion. Starting from the ion in a vibrational coherent state we show how to reverse the sign of the coherent state amplitude by using a purely geometric phase. This can then be detected through the internal degrees of freedom of the ion. Our method can be applied to preparation of entangled states of the ion and the vibrational mode.     

Karhunen-Loeve local characterization of spatiotemporal chaos in a reaction-diffusion system

By computing the Karhunen-Loeve decomposition (KLD) correlation length xi(KLD) of a reaction-diffusion system in the extensive chaos regime, we show that it is a sensitive measure of spatial dynamical inhomogeneities. It reveals substantial spatial nonuniformity of the dynamics at the boundaries and can also detect slow spatial variations in system parameters. The intensive length xi(KLD) can be easily computed from small local subsystems and is found to have a similar parametric dependence as the two-point correlation length computed over the full system size.     

SENSITIZER-INDUCED CONFORMATIONAL CHANGES IN LENS CRYSTALLIN—II. PHOTODYNAMIC ACTION OF RIBOFLAVIN ON BOVINE α-CRYSTALLIN

Abstract— Photolysis of α-crystallin in the presence of riboflavin under both aerobic and anaerobic conditions causes a rapid decrease in Trp emission; photooxidation most likely occurs via non-covalent complex formation between the sensitizer molecule and the substrate. However, the change in the tertiary structure of the protein, as manifested in the near-UV CD, is very different between aerobic and anaerobic photolysis. Riboflavin-sensitized reaction under aerobic condition causes a major change in the microenvironments of thiol groups as well as in the near-UV CD, whereas under anaerobic condition the change in the near-UV CD is much less and SH-group environments remain unaltered. The sensitizer in this photoinduced change in conformation of the protein is very selective and specific.     

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