Di-nuclear systems studied with the velocity filter SHIP

Various nuclear reactions like quasi-fission, fusion-fission or particle and cluster evaporation from excited compound nuclei were studied in heavy-ion reactions at the velocity filter SHIP of GSI. The velocity filter offers the possibility to detect all reaction products under zero degree relative to the beam direction. Together with the measurement of the product velocity distribution this allows for an identification of the underlying reaction mechanism. This article is focussed on reactions of Mg-25 and Ni-64 beams on Pb-206,Pb-207 targets at energies of 5.9 x A MeV and 8.7 x A MeV. Besides evaporation residues from Mg-25 + Pb-206 collisions we found evidence for rotation and quasi-fission of nuclear molecules formed in the entrance channel after the capture stage. The break-up of the systems showed a preferred clustering leading to isotopes in the region 84 <= Z <= 88 and 122 <= N <= 127 of the chart of nuclei.

Nuclear potential and fusion cross sections for synthesizing super-heavy elements in di-nuclear systems

A double folding method with simplified Skyreme-type nucleon-nucleon interaction is used to calculate the nuclear interaction potential between two nuclei. The calculation is performed in tip-to-tip orientation of the two nuclei if they are deformed. Based on this methods, the potential energy surfaces, the fusion probabilities and the evaporation residue cross sections for some cold fusion reactions leading to super-heavy elements within di-nuclear system model are evaluated. It is indicated that after the improvement, the exponential decreasing systematics of the fusion probability with increasing charge number of projectile on the Pb based target become better and the evaporation residue cross sections are in better agreement with the experimental data.

Azimuthal di-hadron correlations in d plus Au and Au plus Au collisions at root s(NN)=200 GeV measured at the STAR detector

Yields, correlation shapes, and mean transverse momenta p(T) of charged particles associated with intermediate-to high-p(T) trigger particles (2.5 < p(T) < 10 GeV/c) in d + Au and Au + Au collisions at root s(NN) = 200 GeV are presented. For associated particles at higher p(T) greater than or similar to 2.5 GeV/c, narrow correlation peaks are seen in d + Au and Au + Au, indicating that the main production mechanism is jet fragmentation. At lower associated particle pT < 2 GeV/c, a large enhancement of the near- (Delta phi similar to 0) and away-side (Delta phi similar to pi) associated yields is found, together with a strong broadening of the away-side azimuthal distributions in Au + Au collisions compared to d + Au measurements, suggesting that other particle production mechanisms play a role. This is further supported by the observed significant softening of the away-side associated particle yield distribution at Delta phi similar to pi in central Au + Au collisions.

Effect of the nucleating agent 1,3 : 2,4-di(3,4-dimethylbenzylidene) sorbitol on the gamma phase content of propylene/ethylene copolymer

The influence of the concentration of a nucleating agent (NA), namely 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS), on the gamma phase content in a propylene/ethylene copolymer was investigated by means of Differential Scanning Calorimetry (DSC), Wide-Angle X-ray Diffraction (WAXD), Small- Angle X-ray Scatter (SAXS) and Polarized Optical Microscopy (POM).

Synergistic extraction and recovery of Cerium(IV) and Fluorin from sulfuric solutions with Cyanex 923 and di-2-ethylhexyl phosphoric acid

Synergistic extraction and recovery of Cerium(IV) (Ce(IV)) and Fluorin (F) from sulfuric solutions using mixture of Cyanex 923 and di-2-ethylhexyl phosphoric acid (D2EHPA) in n-heptane have been carried out. in order to investigate the synergistic extraction of Cyanex 923 + D2EHPA, extraction Ce(IV), F, Ce(III) and Ce-F mixture solution using D2EHPA or Cyanex 923 as extractant alone were studied firstly, and then Synergistic extraction of Ce(IV), F and Ce(IV)-F mixture solution with D2EHPA + Cyanex 923 were carried out. The largest synergistic coefficient of Ce(IV) is obtained at the mole fraction X-Cyanex (923) = 0.8. The synergistic enhancement coefficients (R-max) obtained for Ce(IV) are 23.12 in Ce(IV) solution, and in Ce-F mixed solution R-max for Ce(IV) and F are 2.24 and 3.25 respectively.

Tungsten oxide doped N,N-'-di(naphthalen-1-yl)-N,N-'-diphenyl-benzidine as hole injection layer for high performance organic light-emitting diodes

By introducing tungsten oxide (WO3) doped N,N-'-di(naphthalen-1-yl)-N,N-'-diphenyl-benzidine (NPB) hole injection layer, the great improvement in device efficiency and the organic film morphology stability at high temperature were realized for organic light-emitting diodes (OLEDs). The detailed investigations on the improvement mechanism by optical, electric, and film morphology properties were presented. The experimental results clearly demonstrated that using WO3 doped NPB as the hole injection layer in OLEDs not only reduced the hole injection barrier and enhanced the transport property, leading to low operational voltage and high efficiency, but also improved organic film morphology stability, which should be related to the device stability. It could be seen that due to the utilization of WO3 doped NPB hole injection layer in NPB/tris (8-quinolinolato) aluminum (Alq(3))-based device, the maximum efficiency reached 6.1 cd A(-1) and 4.8 lm W-1, which were much higher than 4.5 cd A(-1) and 1.1 lm W-1 of NPB/Alq(3) device without hole injection layer. The device with WO3 doped NPB hole injection layer yet gave high efficiency of 6.1 cd A(-1) (2.9 lm W-1) even though the device was fabricated at substrate temperature of 80 degrees C.

Investigation of heptakis(2,6-di-O-methyl)-beta-cyclodextrin inclusion complexes with flavonoid glycosides by electrospray ionization mass spectrometry

The non-covalent complexes between three flavonoid glycosides (quercitrin, hyperoside and rutin) and heptakis(2,6-di-O-methyl)-beta-cyclodextrin (DM-beta-CD) were investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The 1:1 complexation of each flavonoid glycoside (guest) to the DM-beta-CD (host) was monitored in the negative ion mode by mixing each guest with an up to 30-fold molar excess of the host. The binding constants for all complexes were calculated by a linear equation in the order: DM-beta-CD:quercitrin > DM-beta-CD:rutin > DM-beta-CD:hyperoside. A binding model for the complexes has also been proposed based on the binding constants and tandem mass spectrometric data of these complexes.

Synthesis and chain-length dependent properties of monodisperse oligo(9,9-di-n-octylfluorene-2,7-vinylene)s

A series of monodisperse oligo(9,9-di-n-octylfluorene-2,7-vinylene)s (OFVs) with fluorene units up to 11 has been synthesized following a divergent approach. Chain length was found to affect not only photophysical properties but also thermal properties. Absorption and photoluminescence spectra are red-shifted with increasing chain length. The effective conjugated length has been extrapolated to be as long as 19 fluorene vinylene units, indicative of a well-conjugated system. With the number of fluorene units > 5, the oligomers exhibit nematic mesomorphism. Glass transition temperature (T-g) and clearing point temperature (T-c) increase with increasing molecular length and with those of OFV11 up to 71 and 230 degrees C, respectively. The oligomers can form uniform films by solution casting for fabrication of light-emitting diodes. With a device structure of ITO/ PEDOT:PSS/OFV11/Ca/Al, a current efficiency of 0.8 cd.A(-1) at a brightness of 1300 cd.m(-2) along with a maximum brightness of 2690 cd.m(-2) have been realized. This performance is notably superior to that of the corresponding polymer.

Effect of silver nanoparticles on luminescent properties of europium complex in di-ureasil hybrid materials

Organic-inorganic hybrids containing luminescent lanthanide complex Eu(tta)(3)Phen (tta = thenoyltrifluoroaceton, phen = 1,10-phenanthroline) and silver nanoparticles have been prepared via mixing rare earth complex and nanoparticles with the precursors of di-ureasil using a sol-gel process. The obtained hybrid materials with transparent and elastomeric features were characterized by transmission electron microscope, solid-state Si-29 magic-angle spinning NMR spectra, diffuse reflectance, UV-visible absorption and photoluminescence spectroscopies. The effect of the silver nanoparticles on the luminescence properties was investigated. The experimental results showed that the luminescence intensity of the Eu(tta)(3)phen complex could be enhanced by less than ca. 9.5 nM of silver nanoparticles with the average diameter of 4 nm, and reached its maximum at the concentration of ca. 3.6 nM. Further increasing the concentration of the silver nanoparticles (> 9.5 nM) made the luminescence quenched. The enchancement and quench mechnism was discussed.

catena-Poly[[[di-mu-acetato-kappa O-4 : O '-bis[(acetato-kappa O-2,O ')manganese(II)]]-di-mu-4,4 '-bipyridine-kappa N-4 : N '] monohydrate

The title compound, {[Mn-2(CH3CO2)(4)(C10H8N2)(2)](H2O)-H-.}(n), is a one-dimensional coordination polymer with a ladder-like structure. Two Mn-II atoms, each coordinated by a chelating acetate ligand, are bridged by two bidentate acetate ligands to form a centrosymmetric [Mn-2(CH3CO2)(4)] unit. Two 4,4'-bipyridine ligands link the [Mn-2(CH3CO2)(4)] units through Mn-N bonds to generate a molecular ladder. The water O atom lies on a crystallographic twofold rotation axis.

Loosely packed self-assembled monolayer of N-hexadecyl-3,6-di(p-mercaptophenylacetylene)carbazole on gold and its application in biomimetic membrane research

Dithiols of N-hexadecyl-3,6-di(p-mercaptophenylacetylene)carbazole (HDMC) have been synthesized and employed to form self-assembled monolayers (SAMs) on gold. One characteristic of the HDMC molecule is its peculiar molecular structure consisting of a large and rigid headgroup and a small and flexible alkyl-chain tail. HDMC adsorbates can attach to gold substrates by a strong Au-S bond with weak van der Waals interactions between the alkyl-chain tails, leading to a loosely packed hydrophobic SAM. In this way we can couple hybrid bilayer membranes (HBMs) to gold surfaces with more likeness to a cell bilayer than the conventional HBMs based on densely packed long-chain alkanethiol SAMs. The insulating properties and stability of the HDMC monolayer as well as the HDMC/lipid bilayer on gold have been investigated by electrochemical techniques including cyclic voltammetry and impedance spectroscopy. To test whether the quality of the bilayer is sufficiently high for biomimetic research, we incorporated the pore-forming protein a-hemolysin) and the horseradish peroxidase into the bilayers, respectively.

Morphology and structure of poly(di-n-butylsilane) single crystals prepared by controlling kinetic process of solvent evaporation

The silicon backbone conformation in poly(di-n-butylsilane) (PDBS) has been shown to be a 7/3 helix at ambient conditions, which is in marked contrast to the near-planar conformation of its homologous polymers with side chain lengths of one to three or six to eight carbon atoms. In this work, both the 7/3 helical and near-planar chain conformations are achieved by controlling the solvent evaporation rate around room temperature. The chain conformation and crystal structure obtained in this method have been correlated to the crystal morphology by wide-angle X-ray diffraction, transmission electron microscopy, electron diffraction, optical microscopy, atomic force microscopy, and UV absorption spectrum. The lath-shaped single crystals obtained at 12 degreesC correspond to an orthorhombic form with near-planar chain conformation whereas the lozenge-shaped single crystals obtained at 30 degreesC (in coexistence with the lath-shaped crystals) are orthohexagonal with a 7/3 helix.