Experiments and modification on electron cyclotron resonance ion sources at the Institute of Modern Physics

Uranium ion beams were produced from electron cyclotron resonance (ECR) ion sources by sputtering method this year at the Institute of Modern Physics. At first, we chose the Lanzhou ECR No. 3 ion source to implement the production experiment of U ion beams. Finally, 11 e mu A of U28+, 5 e mu A of U32+, and 1.5 e mu A of U35+ were obtained. A U26+ ion beam produced by the LECR2 ion source was accelerated successfully by the cyclotron. This means that the Heavy Ion Research Facility in Lanzhou (HIRFL) has accomplished the acceleration of the ion beam of the heaviest element according to the designed parameters. The Lanzhou ECR ion source No. 2 (LECR2), which was built in 1997, has served the HIRFL for eight years and needed to be upgraded to provide more intense high charge state ion beams for HIRFL cooling storage ring. We started the upgrading project of LECR2 last year, and the modified design just has been finished. (c) 2006 American Institute of Physics.

Study on the localization of the electric dipole sources

The research of dipole source localization has great significance in both clinical research and applications. For example, the EEG recording from the scalp is widely used for the localization of sources of electrical activity in the brain. This paper presents a closed formula that describes the electric field of dipoles at arbitrary position, which is a linear transformer called the transfer matrix. The expression of transfer matrix and its many useful characteristics are given, which can be used for the analysis of the electrical fields of dipoles. This paper also presents the closed formula for determining the location and magnitude of single dipole or multi-dipoles according to its electrical field distribution. A calculation result for a single dipole shows that the dipole will be located at the midpoint of a line segment if there are equivalent fields at its two ends.

General SU(2)(L) x SU(2)(R) x U(1)(EM) sigma model with external sources, dynamical breaking and spontaneous vacuum symmetry breaking

We give a general SU(2)(L) x SU(2)(R) x U(1)(EM) sigma model with external sources, dynamical breaking and spontaneous vacuum symmetry breaking, and present the general formulation of the model. It is found that sigma and pi(0) without electric charges have electromagnetic interaction effects coming front the internal structures. A general Lorentz transformation relative to external sources J(gauge) - (J(A mu) J(A mu)(kappa)) derived, using the general Lorentz transformation and the four-dimensional current of nuclear matter of the ground si ate with J(gauge) = 0, we give the four-dimensional general relations between the different currents of nuclear matter systems with J(gauge) not equal 0 and those with J(gauge) = 0. The relation of the density's coupling with external magnetic field is derived, which conforms well to dense nuclear matter in a strong magnetic field. We show different condensed effects in strong interaction about fermions and antifermions, and give the concrete scalar and pseudoscalar condensed expressions of sigma(0) and pi(0) bosons. About different dynamical breaking and spontaneous vacuum symmetry breaking, the concrete expressions of different mass spectra are obtained in field theory. This paper acquires the running spontaneous vacuum breaking value sigma'(0), and obtains the spontaneous vacuum breaking in tenus of the running sigma'(0), which make nucleon, sigma, and pi particles gain effective masses. We achieve both the effect of external sources and nonvanishing value of the condensed scalar and pseudoscalar paticles. It is deduced that the masses of nucleons, sigma and pi generally depend on different external sources.

Characterization of structure and diffusion behaviour of Ca-alginate beads prepared with external or internal calcium sources

Ca-alginate beads were prepared with either external or internal calcium sources. The structures of both beads were investigated with the aid of scanning electron microscopy (SEM) and confocal microscopy. It was shown that the beads with internal calcium source had a looser structure and bigger pore size than those with external calcium source. The attempts to interpret the difference were carried out by determining the Ca content within the beads at various times, which indicated that it was the different gelation mechanisms that caused the difference of structures of both beads. Furthermore, it was also found that the diffusion rate of haemoglobin (Hb) within the beads with an internal calcium source was faster than that of the beads with an external one, which was consistent with the observation of their structures.

Sulfonated poly(ether ether ketone)/clay-SO3H hybrid proton exchange membranes for direct methanol fuel cells Journal of Power Sources

A new type of sulfonated clay (clay-SO3H) was prepared by the ion exchange method with the sulfanilic acid as the surfactant agent. The grafted amount of sulfanilic acid in clay-SO3H was 51.8 mequiv. (100 g)(-1), which was measured by thermogravimetric analysis (TGA). Sulfonated poly(ether ether ketone) (SPEEK)/clay-SO3H hybrid membranes which composed of SPEEK and different weight contents of clay-SO3H, were prepared by a solution casting and evaporation method. For comparison, the SPEEK/clay hybrid membranes were produced with the same method.

Different microstructures of ss-NaYF4 fabricated by hydrothermal process: Effects of pH values and fluoride sources

beta-NaYF4 microcrystals with a variety of morphologies, such as microrod, hexagonal microprism, and octadecahedron, have been synthesized via a facile hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra were used to characterize the samples. The intrinsic structural feature of beta-NaYF4 seeds and two important external factors, namely, the pH values in the initial reaction solution and fluoride sources, are responsible for shape determination of beta-NaYF4 microcrystals. It is found that the organic additive trisodium citrate (Cit(3-)) as a shape modifier has the dynamic effect by adjusting the growth rate of different facets under different experimental conditions, resulting in the formation of the anisotropic geometries of various beta-NaYF4 microcrystals. The possible formation mechanisms for products with various architectures have been presented. A systematic study on the photoluminescence of Tb3+-doped beta-NaYF4 samples with rod, prism, and octadecahedral shapes has shown that the optical properties of these phosphors are strongly dependent on their morphologies and sizes.

Solution-processible multi-component cyclometalated iridium phosphors for high-efficiency orange-emitting OLEDs and their potential use as white light sources

The synthesis and photophysical studies of several multifunctional phosphorescent iridium(III) cyclometalated complexes consisting of the hole-transporting carbazole and fluorene-based 2-phenylpyridine moieties are reported. All of them are isolated as thermally and morphological stable amorphous solids. Extension of the pi-conjugation through incorporation of electron- pushing carbazole units to the fluorene fragment leads to bathochromic shifts in the emission profile, increases the highest oc- cupied molecular orbital levels and improves the charge balance in the resulting complexes because of the propensity of the carbazole unit to facilitate hole transport. These iridium-based triplet emitters give a strong orange phosphorescence light at room temperature with relatively short lifetimes in the solution phase. The photo- and electroluminescence properties of these phosphorescent carbazolylfluorene-functionalized metalated complexes have been studied in terms of the coordinating position of carbazole to the fluorene unit. Organic light-emitting diodes (OLEDs) using these complexes as the solution-processed emissive layers have been fabricated which show very high efficiencies even without the need for the typical hole-transporting layer.I These orange-emitting devices can produce a maximum current efficiency of similar to 30 cd A(-1) corresponding to an external quantum efficiency of similar to 10 % ph/el (photons per electron) and a power efficiency of similar to 14 Im W-1.

Reagent-controlled asymmetric iodolactonization using cinchona alkaloids as chiral sources

A novel method for reagent-controlled asymmetric iodolactonization of 5-aryl-4-pentenoic acids is reported. This work uses carboxylate ion pairs combined with cinchona alkaloids as chiral sources of carboxylate anion for the first time leading to a mixture of two regio-isomeric iodolactones with moderate enantioselectivity (exo- 18.5% ee, endo-35.0% ee) under mild reaction conditions.

REE and epsilon(Nd) of clay fractions in sediments from the eastern Pacific Ocean: Evidence for clay sources

Clay fractions in the non-calcareous surface sediments from the eastern Pacific were analyzed for clay minerals, REE and Nd-143/Nd-144. Montmorillonite/illite ratio (M/I ratio), total REE contents (Sigma REE), LREE/HREE ratio and cerium anomaly (delta Ce) may effectively indicate the genesis of clay minerals. Clay fractions with M/I ratio > 1, delta Ce < 0.85, Sigma REE > 400 mu g/g, LREE/HREE ratio approximate to 4, and REE patterns similar to those of pelagic sediments are terrigenous and autogenetic mixed clay fractions and contain more autogenetic montmorillonite. Clay fractions with M/I ratio < 1, delta Ce=0.86 to 1.5, Sigma REE=200 to 350 mu g/g, LREE/HREE ratio approximate to 6 and REE distribution patterns similar to that of China loess are identified as terrigenous clay fraction. The Nd-143/Nd-144 ratios or epsilon(Nd) values of clay fractions inherit the features of terrigenous sources of clay minerals. Clay fractions are divided into 4 types according to epsilon(Nd) values. Terrigenous clay minerals of type I with the eNd values of -8 to -6 originate mainly from North American fluvial deposits. Those of type 11 with the epsilon(Nd) Values of -9 to -7 are mainly from the East Asia and North American fluvial deposits. Those of type III with epsilon(Nd) values of -6 to -3 could come from the central and eastern Pacific volcanic islands. Those of type IV with epsilon(Nd) values of -13 to -12 may be from East Asia eolian. The terrigenous and autogenetic mixed clay fractions show patchy distributions, indicating that there are volcanic or hot-spot activities in the eastern Pacific plate, while the terrigenous clay fractions cover a large part of the study area, proving that the terrigenous clay minerals are dominant in the eastern Pacific.