New development of advanced superconducting electron cyclotron resonance ion source SECRAL (invited)

Superconducting electron cyclotron resonance ion source with advance design in Lanzhou (SECRAL) is an 18-28 GHz fully superconducting electron cyclotron resonance (ECR) ion source dedicated for highly charged heavy ion beam production. SECRAL, with an innovative superconducting magnet structure of solenoid-inside-sextupole and at lower frequency and lower rf power operation, may open a new way for developing compact and reliable high performance superconducting ECR ion source. One of the recent highlights achieved at SECRAL is that some new record beam currents for very high charge states were produced by 18 GHz or 18+14.5 GHz double frequency heating, such as 1 e mu A of Xe-129(43+), 22 e mu A of Bi-209(41+), and 1.5 e mu A of Bi-209(50+). To further enhance the performance of SECRAL, a 24 GHz/7 kW gyrotron microwave generator was installed and SECRAL was tested at 24 GHz. Some promising and exciting results at 24 GHz with new record highly charged ion beam intensities were produced, such as 455 e mu A of Xe-129(27+) and 152 e mu A of Xe-129(30+), although the commissioning time was limited within 3-4 weeks and rf power only 3-4 kW. Bremsstrahlung measurements at 24 GHz show that x-ray is much stronger with higher rf frequency, higher rf power. and higher minimum mirror magnetic field (minimum B). Preliminary emittance measurements indicate that SECRAL emittance at 24 GHz is slightly higher that at 18 GHz. SECRAL has been put into routine operation at 18 GHz for heavy ion research facility in Lanzhou (HIRFL) accelerator complex since May 2007. The total operation beam time from SECRAL for HIRFL accelerator has been more than 2000 h, and Xe-129(27+), Kr-78(19+), Bi-209(31+), and Ni-58(19+) beams were delivered. All of these new developments, the latest results, and long-term operation for the accelerator have again demonstrated that SECRAL is one of the best in the performance of ECR ion source for highly charged heavy ion beam production. Finally the future development of SECRAL will be presented.

New parameters of many-body potentials: studying the thermal and mechanical properties of noble metals

New parameters of nearest-neighbor EAM (1N-EAM), n-th neighbor EAM (NN-EAM), and the second-moment approximation to the tight-binding (TB-SMA) potentials are obtained by fitting experimental data at different temperatures. In comparison with the available many-body potentials, our results suggest that the 1N-EAM potential with the new parameters is the best description of atomic interactions in studying the thermal expansion of noble metals. For mechanical properties, it is suggested that the elastic constants should be calculated in the experimental zero-stress states for all three potentials. Furthermore, for NNEAM and TB-SMA potentials, the calculated results approach the experimental data as the range of the atomic interaction increases from the first-neighbor to the sixth-neighbor distance.

Syndiotactically enriched 1,2-selective polymerization of 1,3-butadiene initiated by iron catalysts based on a new class of donors

A series of phosphoryl (P=O) contained compounds: triethylphosphate (a), diethyl phenyl phosphate (b), ethyldiphenylphosphate (c) triarylphosphates (d and h-m), triphenylphosphine oxide (e), phenyl diphenylphosphinate (f) and diphenyl phenylphosphonate (g) have been prepared. Iron catalysts, which are generated in situ by mixing the compounds with Fe(2-EHA)(3) and (AlBu3)-Bu-i in hexane, are tested for butadiene polymerization at 50 degrees C. Phosphates donated catalysts have been, unprecedently, found to conduct extremely high syndiotactically (pentad, rrrr=46.1-94.5%) enriched 1,2-selective (1,2-structure content=56.2-94.3%) polymerization of butadiene.

Potassium-Lead-Switched G-Quadruplexes: A New Class of DNA Logic Gates

A cation-driven allosteric G-quadruplex DNAzyme (PW17) was utilized to devise a conceptually new class of DNA logic gate based on cation-tuned ligand binding and release. K+ favors the binding of hemin to parallel-stranded PW17, thereby promoting the DNAzyme activity, whereas Pb2+ induces PW17 to undergo a parallel-to-antiparallel conformation transition and thus drives hemin to release from the G-quadruplex, deactivating the DNAzyme. Such a K+-Pb2+ switched G-quadruplex, in fact, functions as a two-input INHIBIT logic gate. With the introduction of another input EDTA, this G-quadruplex can be further utilized to construct a reversibly operated IMPLICATION gate.

Reactive compatibilization of LLDPE/PS blends with a new type of Lewis acid as catalyst

The reactive compatibilization of LLDPE/PS (50/50 wt%) was achieved by Friedel-Crafts alkylation reaction with a combined Lewis acids (Me3SiCl and InCl3 center dot 4H(2)O) as catalyst. The graft copolymer at the interface was characterized by Fourier transform infrared spectroscopy and the morphology of the blends was analysized by scanning electron microscopy. It was found that the combined Lewis acids had catalytic effect on Friedel-Crafts alkylation reaction between LLDPE and PS, and the catalytic effect was maximal when the molar ratio of InCl3 center dot 4H(2)O to Me3SiCl was 1:5. The graft copolymer LLDPE-g-PS was formed via the F-C reaction and worked as a tailor-made compatibilizer to reduce the interfacial tension. The mechanical properties of reactive blend with combined Lewis acids as catalyst was notably improved compared to that of physical LLDPE/PS blend and serious degradation had been decreased compared to the reactive blend system with AlCl3 as catalyst; we interpreted the above results in term of acidity of combined Lewis acids.

A new class of high T-g and organosoluble polynaphthalimides

A new class of soluble six-membered ring polynaphthalimides (PNIs) was synthesized from asymmetrical fluorinated naphthalenesubstituted monomers. All the resulting PNIs were easily soluble in many organic solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO). and chloroform. They also showed good thermal stability with glass transition temperature of 340-386 degrees C, 10% weight loss temperature in excess of 529 degrees C. Polyimide 3c could be solution-cast into tough and flexible film. The film had a tensile strength, elongation at break, and Young's modulus of about 117.6 Wa, 23.6%, and 1.77 GPa, respectively. The gas permeation property of the film of 3c was investigated with oxygen permeability coefficient (PO2 = 3.99) and permeability selectivity coefficient of oxygen to nitrogen (P-O2/P-N2 = 5.27). Therefore, these materials are expected to be a good alternative to PIs based on five-membered rings with applications in gas separation membranes.

Structural determination of a new phase of monoclinic BaTb2Mn2O7

A new phase of monoclinic BaTb2Mn2O7 with extra superlattice lines in addition to the usual orthorhombic X-ray diffraction patterns was prepared and a Rietveld refinement was applied to analyze the crystal structure using X-ray powder diffraction data at room temperature. The refined lattice parameters were a = 0.54918(8) nm, b = 2.0149(5) nm, c = 0.54922(9) nm, and beta = 90.62degrees with the space group A2/m (no. 12). The MnO6 oxygen octahedron has distortion and tilts around a-axis by about 7degrees each other in the reverse direction.

A new family of Ce6MoO15 as fast oxide ion conductor

A novel solid solution Ce6MoO15 was achieved. Their structure and oxide ionic conductivity were studied. Based on Ce6MoO15, rare earth element substitution on cerium site shows that all resulting oxides enhance the conductivity further, and have high oxide-ion conductivity, which may be a kind of promising material for SOFCs.

A new type of highly efficient luminescent material - The system Al2O3-B2O3 containing Ce3+ and Tb3+ ions

The system Al2O3-B2O3 containing Ce3+ and Tb3+ ions was investigated for the first time. It was found that certain compositions give rise to a new highly efficient green luminescent material.