Theory of sheath in a collisional multi-component plasma

The aim of this brief report is to study the behaviour of sheath structure in a multi-component plasma with dust-neutral collisions. The plasma consists of electrons, ions, micron size negatively charged dust particles and neutrals. The sheath-edge potential and sheath width are calculated for collisionally dominated sheath. Comparison of collisionless and collisionally dominated sheath are made.     

Spin squeezing and quantum correlations

We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among the spinors in the coupled state.     

Nanoscale Borromean links for real

Borohydride reduction of a Borromean Ring (BR) complex containing six zinc(II) ions and 12 imine bonds has resulted in its demetallation, producing a neutral BR compound and also its free macrocycle, following cleavage of at least one of the imine bonds in the ethanolic reaction mixture.     

Nanoscale borromeates

[Structure: See text] In addition to a parent zinc(II) Borromean ring (BR) complex, the preparation and characterization of two hexasubstituted BR complexes with either 4-acetoxymethylphenyl or 4-methylthiophenyl substituents associated in turn with all six pyridyl rings has been achieved convergently in good yields by appealing to the dynamic features of the reactions between primary amino groups in a preformed acyclic ligand and 2,6-diformylpyridine. Two molecules of the acyclic ligands react with two molecules of 2,6-diformylpyridine to form a cyclic [2 + 2] tetraimine in the presence of Zn(II) ions as templates in 2-propanol at 70 degrees C. The successful preparation of the two derivatives by convergent template-directed syntheses opens up opportunities to self-assemble, under equilibrium control, numerous nanoscale metallo-organic particles with potentially useful properties.     

Analysis of a shielded TE011 mode composite dielectric resonator for stable frequency reference

Analysis of a TE₀₁₁ mode composite sapphire-rutile dielectric resonator has been carried out to study the temperature variation of resonance frequency, close to the Cs atomic clock hyperfine frequency of 9.192 GHz. The complementary behavior of dielectric permittivity with temperature of the composite has been exploited to obtain the desired turning point in the resonant frequency. The frequency of the composite structure is found to be independent of the shield diameter beyond four times the puck diameter.     

Supramolecular metal-polypyridyl and Ru(II) porphyrin complexes: photophysical, electron paramagnetic resonance, and electrochemical studies

A series of mixed-metal supramolecular porphyrin arrays in which the geometry of the central metal-polypyridyl moiety defines the spatial arrangement of two or more Ru(II)-porphyrin units through axial coordination have been prepared by employing self-assembly based protocols, and their photophysical and electrochemical properties have been studied. The electrochemical properties of the constituent parts of these arrays depend only on their own chemical environment, regardless of the nuclearity and the overall charge of the compound; in this way species with predetermined redox patterns can be obtained via the synthetic control of the self-assembly process. Interestingly, several of these arrays are luminescent both at room and at low temperatures, and in many cases core-to-periphery or periphery-to-core intramolecular energy transfer processes take place according to the nature of the central metal template.     

Pressure dependence of the superconducting state parameters of metallic glass superconductor Mg70Zn30

Explicit expressions have been derived for the volume dependence of electron-phonon coupling strength (λ) and the Coulomb pseudopotential (μ^*) considering the variation of Fermi momentum (κ _F) and Debye temperature (θ _D) with volume. Ashcroft’s model pseudopotential and RPA form of dielectric screening have been used for obtaining pressure dependence of transition temperature (T _C) and the logarithmic volume derivative (Φ) of the effective interaction strength (N ₀ V) for metallic glass superconductor Mg₇₀Zn₃₀. It has been observed that T _C of the metallic glass Mg₇₀Zn₃₀ decreases rapidly with increase of pressure and the superconducting phase disappears at about 30% decrease of volume, for which the μ^* curve shows a minimum and an elbow is formed in the Φ graph.