Compensating the noise of a communication channel via asymmetric encoding of quantum information

An asymmetric preparation of the quantum states sent through a noisy channel can enable a new way to monitor and actively compensate the channel noise. The paradigm of such an asymmetric treatment of quantum information is the Bennett 1992 protocol, in which the counts in the two separate bases are in direct connection with the channel noise. Using this protocol as a guiding example, we show how to correct the phase drift of a communication channel without using reference pulses, interruptions of the quantum transmission, or public data exchanges.     

Catalytic application of dinuclear palladium(II) bis(thiosemicarbazone) complex in the Mizoroki-Heck reaction

A convenient synthesis of new square planar dinuclear palladium(II) terephthaldehyde bis(thiosemicarbazone) complex has been described. The compositions of the complex have been established by elemental analysis, spectral methods and single crystal X-ray crystallographic technique. The new complex acts as an active recyclable homogeneous catalyst for the Mizoroki-Heck reaction of electron deficient (activating) and electron rich (deactivating) aryl halides with various olefins under optimized conditions.     

An efficient total synthesis of calothrixin B

An efficient synthesis of calothrixin B (2) is demonstrated starting from 9H-carbazol-4-ol, having two one-pot reaction sequences as key steps. As a novel observation, DMF–methanol was shown to be a hydride donor for reduction of aldehyde to alcohol. Unexpectedly, nucleophilic substitution of benzyloxy by methoxy group was observed.     

Anthracen-9-ylmethylene-(4-methoxyphenyl)amine: efficient promoter for silver-free palladium-catalyzed aerobic oxidative Sonogashira reactions

An efficient protocol for the synthesis of unsymmetrical substituted diarylacetylenes by the C(sp²)–C(sp) cross-coupling reactions of substituted phenylacetylenes and electronically different arylboronic acids has been developed. Anthracen-9-ylmethylene-(4-methoxyphenyl)amine was employed as an efficient promoter in this Pd(OAc)₂-catalyzed oxidative Sonogashira reaction in air in the absence of silver salt under optimized reaction conditions. The impact of reaction parameters such as solvent, base, reaction temperature and time in this silver-free aerobic oxidative Sonogashira cross-coupling reaction was also evaluated. Electron-deficient phenylacetylenes, which are sluggish coupling partners in the traditional Sonogashira reaction, underwent coupling in this protocol. The catalytic system is inexpensive, effortlessly attainable and highly flexible for functionalized phenylacetylenes and arylboronic acids.

Graphic abstract

     

Influence of corner stresses on the stability characteristics of composite skew plates

Stability characteristics of composite skew plates subjected to in-plane compressive load are investigated here using the shear deformable finite element approach. The influences of high prebuckling stresses at the corner regions of isotropic and composite skew plates on their stability characteristics are emphasized for different load direction, boundary condition and laminate stacking sequence. The non-linear governing equations based on von Kármán's assumptions are solved by Newton-Raphson technique to get the hitherto unreported postbuckling equilibrium paths of composite skew plates loaded between two rigid flat platens. The variation of out-of-plane deformation and end-shortening with compressive in-plane load are examined for simply supported and clamped skew plates made of isotropic, symmetric and unsymmetric laminates. Marguerre's shallow shell theory is employed to study the effect of sinusoidal imperfection on the non-linear behavior of composite skew plates.     

Direct numerical simulation of free falling sphere in creeping flow

In the present study, direct numerical simulations (DNS) are performed on single and a swarm of particles settling under the action of gravity. The simulations have been carried out in the creeping flow range of Reynolds number from 0.01 to 1 for understanding the hindrance effect, of the other particles, on the settling velocity and drag coefficient. The DNS code is a non-Lagrange multiplier-based fictitious-domain method, which has been developed and validated by Jin et al. (2008 Jin, S. A parallel algorithm for the direct numerical simulation of 3D inertial particle sedimentation. Conference proceedings of the 16th annual conference of the CFD Society of Canada. Edited by: Bergstrom, D. J. and Spiteri, R. 9–11, June. Saskatoon, Saskatchewan, , Canada [Google Scholar]; A parallel algorithm for the direct numerical simulation of 3D inertial particle sedimentation. In: Conference proceedings of the 16th annual conference of the CFD Society of Canada). It has been observed that the time averaged settling velocity of the particle in the presence of other particles, decreases with an increase in the number of particles surrounding it (from 9 particles to 245 particles). The effect of the particle volume fraction on the drag coefficient has also been studied and it has been observed that the computed values of drag coefficients are in good agreement with the correlations proposed by Richardson and Zaki (1954 Richardson, J. F. and Zaki, W. N. 1954. Sedimentation and fluidization: part I. Transactions of the Institution of Chemical Engineers, 32: 35–53.  [Google Scholar]; Sedimentation and fluidization: part I. Transactions of the Institution of Chemical Engineers, 32, 35–53) and Pandit and Joshi (1998 Pandit, A. B. and Joshi, J. B. 1998. Pressure drop in packed, expanded and fluidized beds, packed columns and static mixers – a unified approach. Reviews in Chemical Engineering, 14: 321–371. [Crossref], [Web of Science ®] , [Google Scholar]; Pressure drop in packed, expanded and fluidised beds, packed columns and static mixers – a unified approach. Reviews in Chemical Engineering, 14, 321–371). The suspension viscosity-based model of Frankel and Acrivos (1967 Frankel, N. A. and Acrivos, A. 1967. On the viscosity of a concentrated suspension of solid spheres. Chemical Engineering Science, 22: 847–853. [Crossref], [Web of Science ®] , [Google Scholar]; On the viscosity of a concentrated suspension of solid spheres. Chemical Engineering Science, 22, 847–853) shows good agreement with the DNS results.     

Nickel(II) thiosemicarbazone complex catalyzed Mizoroki–Heck reaction

Convenient synthesis of a new square planar nickel(II) naphthaldehyde thiosemicarbazone complex has been described. The composition of the complex has been established by elemental analysis, spectral methods, and single crystal X-ray crystallography. The new complex acts as an active homogeneous catalyst for the Mizoroki–Heck reaction of electron deficient (activating) and electron rich (deactivating) aryl bromides with various olefins under optimized conditions.     

New 1,8-naphthyridine-based probes for the selective fluorescence signalling of toxic cadmium: synthesis,photophysical studies and molecular modelling

Newly synthesised 1,8-naphthyridine-based molecular probes, NAP-1 and NAP-2, exhibit highly selective fluorescence responses towards the toxic cadmium over coordinatively competing Zn²⁺ and several other metal ions examined. On the one hand, NAP-1 (MeOH:H₂O, v/v 80:20, pH 7.4) exhibits ca. 1.5 order of magnitude higher stability constant for Cd²⁺ over Zn²⁺; on the other hand, NAP-2 in MeOH offers unique selectivity only towards Cd²⁺, exhibiting both absorbance and emission red shifts as well as fluorescence enhancement. By ¹H NMR analysis, the tetra-coordinated binding is indicated at least for the NAP-1+Cd²⁺ complex and theoretical calculations reveal relatively stronger binding of Cd²⁺ over Zn²⁺.

     

On some exact solutions of slightly variant forms of Yang’s equations and their graphical representations

The equations obtained by Yang while discussing the condition of self-duality of SU(2) gauge fields on Euclidean four-dimensional space have been generalized. Exact solutions and their graphical representations for the generalized equation (for some particular values of the parameters) have been reported. They represent interesting physical characteristics like waves with spreading solitary profile, spreading wave packets, waves with pulsating solitary profile (between zero and a maximum), waves with oscillatory solitary profile and chaos.