Optimizing the rapidity limit for nuclear stopping in intermediate energy heavy-ion collisions

A systematic study regarding the role of participant matter and spectator matter in nuclear stopping using isospin-dependent quantum molecular dynamics model is presented. The simulations have been carried out with soft equation of state along with the reduced isospin-dependent cross section to study the effect of different types and sizes of rapidity distributions on nuclear stopping for the whole colliding geometry with density-dependent symmetry energy. In addition to that, we attempt to investigate the role of isospin in heavy-ion collisions by calculating the individual contribution of neutrons and protons in nuclear stopping for different systems having different isotopic content.     

Enhanced coherent emission aided by an incoherent process

Enhanced emission of a coherent signal generated by the nonlinear process omega(f)+omega(b)-omega(p) has been found in an incoherently pumped four-level system. It is shown that finite (large) atomic coherence can be generated by (incoherent) pumping of the intermediate states, which removes the destructive interference effects that otherwise inhibit coherent emission of signals.     

A programmable molecular diode driven by charge-induced conformational changes

The 3-nitro-2-(3'-nitro-2'-ethynylpyridine)-5-thiopyridine molecule shows charge-induced conformational switching and a rectifying behavior with a charge-induced controllable switching. This device can be used as a memory operated with an external field interacting with one of the rings local dipole. Alternatively, the molecule can be used as a nano-actuator controlling the rotation of the ring by charging the molecule with a bias voltage.     

Rapidity distribution as a probe for elliptical flow at intermediate energies

The interplay between spectator and participant matter in heavy-ion collisions is investigated within the isospin-dependent quantum molecular dynamics (IQMD) model in terms of the rapidity distribution of light charged particles. The effect of different types and sizes of rapidity distributions is studied in elliptical flow. The elliptical-flow patterns show the important role of nearby spectator matter on the participant zone. This role is further explained on the basis of the passing time of the spectator and the expansion time of the participant zone. The transition from in-plane to out-of-plane emission is observed only when the mid-rapidity region is included into the rapidity bin. Otherwise no transition occurs. The transition energy is found to be highly sensitive to the size of the rapidity bin, while it is only weakly dependent on the type of the rapidity distribution. These theoretical findings are found to be in agreement with experimental results.     

Synthesis of a new heterocyclic ring system 2,3,5,6,7,9,10,11-octahydro-lH-cyclopenta[9,H)]benzo[i,j] quinolizine-1,9-dione

Reaction of 1,2,3,4-tetrahydroquinoline (1) with different α,β-unsaturated acids in the presence of PPA has been investigated. With acrylic acid, 1 affords two compounds identified as 1-keto-benzo[i,j]quinolizine (III) and 2,3,5,6,7,9,10,1 1-octahy dro-1H-cy el open ta [9,10] benzo [i,j]-quinolizine-1,9-dione (IV). A similar reaction of 1 with a-methyl acrylic and crotonie acids gives compounds V and VI whose structures are analogous to that of IV. These were deduced from their spectral and analytical data.     

Self-catalyzed vapor–liquid–solid growth of InP/InAsP core–shell nanopillars

Indium phosphide/indium arsenide phosphide core–shell nanopillars have been prepared by the vapor–liquid–solid method using liquid indium droplets as the catalyst. The indium droplets were generated in situ in the deposition reactor. The hexagonal nanopillars exhibited hexagonal shaped sidewalls with average width and height of 150 and 250 nm, respectively. Cross-section transmission electron microscopy with selected area electron diffraction and X-ray dispersion energy analysis verified that an InAsP layer, approximately 10 nm thick, coated the pillars. Photoluminescence spectra at 77 K yielded an extremely intense band at 0.76 eV (1.63 μm), which was due to the InAsP shell on the pillars.     

Convenient and rapid synthesis of α-aminonitriles starting directly from nitro compounds in water

A distinct approach for the synthesis of α-aminonitriles has been discovered by three-component reaction of nitroarenes, aldehydes, and TMSCN using indium in dilute aqueous HCl at room temperature. The products were formed in high yields (86-96%) within a short period of time (5-20 min). This one-pot conversion consists of the following steps: (i) reduction of nitro compounds to amines, (ii) formation of imines from amines and aldehydes and (iii) addition of cyanide anion to the imines.     

Synthesis of calix[4]arene(amido)monocrowns and their photoresponsive derivatives

A series of new calix[4]arene(amido)mono-crown compounds have been synthesized through aminolysis of calix[4]arene esters and intramolecular cyclization of the intermediates. The title compounds were converted into their nitro and azo substituted derivatives to provide novel photoresponsive molecular receptors for transition metal ions. Single crystal X-ray analysis of calix[4]arene(ethyleneamido)mono-crown (2a) revealed that the compound is present in a cone conformation with an amido loop that caps the lower rim of calix[4]arene cavity to result in stacking along axis a and axis c to provide supramolecular aggregates in the solid state. Evaluation of synthesized macrocycles in the solution phase for recognition of transition metal cations (Cr³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, Pb²⁺, Hg⁺, Hg²⁺, Pd²⁺, and Pt²⁺) by UV-visible spectroscopy revealed that p-tert-butyl-calix[4]arene mono-(amidocrown) 1c selectively shows a blue shift at 38 nm on interaction with Hg⁺ ions.