Synthesis of Cu2O coated Cu nanoparticles and their successful applications to Ullmann-type amination coupling reactions of aryl chlorides

We synthesized uniform Cu2O coated Cu nanoparticles from the thermal decomposition of copper acetylacetonate followed by air oxidation and used these nanoparticles as catalysts for Ullmann type amination coupling reactions of aryl chlorides     

Complete conditions for entanglement transfer

We investigate the conditions to entangle two qubits interacting with local environments driven by a continuous-variable correlated field. We find the conditions to transfer the entanglement from the driving field to the qubits both in dynamical and steady-state cases. We see how the quantum correlations initially present in the driving field play a critical role in the entanglement-transfer process. The system we treat is general enough to be adapted to different physical setups.     

Golmaenone, a new diketopiperazine alkaloid from the marine-derived fungus Aspergillus sp

A new diketopiperazine alkaloid, golmaenone (1). and related alkaloids, neoechinulin A (2). and L-alanyl-L-tryptophan anhydride (3). have been isolated from the culture broth of the marine-derived fungus Aspergillus sp. The structure and absolute stereochemistry of the new compound (1). was assigned by spectroscopic methods and the advanced Marfey's method. Compounds 1 and 2 exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC(50) values of 20 and 24 microM, respectively, which are similar to the positive control, ascorbic acid (IC(50), 20 microM). Compounds 1 and 2 also showed an ultraviolet-A (UV-A) (320--390 nm) protecting activity with ED(50) values of 90 and 170 microM, respectively, which are more active than oxybenzone (ED(50), 350 microM) currently being used as sunscreen.     

A fast spin echo two-point Dixon technique and its combination with sensitivity encoding for efficient T2-weighted imaging

A fast spin echo two-point Dixon (fast 2PD) technique was developed for efficient T2-weighted imaging with uniform water and fat separation. The technique acquires two interleaved fast spin echo images with water and fat in-phase and 180° out-of-phase, respectively, and generates automatically separate water and fat images for each slice. The image reconstruction algorithm uses an improved and robust region-growing scheme for phase correction and achieves consistency in water and fat identification between different slices by exploiting the intrinsic correlation between the complex images from two neighboring slices. To further lower the acquisition time to that of a regular fast spin echo acquisition with a single signal average, we combined the fast 2PD technique with sensitivity encoding (SENSE). Phantom experiments show that the fast 2PD and SENSE are complementary in scan efficiency and signal-to-noise ratio (SNR). In vivo data from scanning of clinical patients demonstrate that T2-weighted imaging with uniform and consistent fat separation, including breath-hold abdominal examinations, can be readily performed with the fast 2PD technique or its combination with SENSE.     

Effective lagrangian and topological interactions in supersolids

We construct a low-energy effective Lagrangian describing zero temperature supersolids. Galilean invariance imposes strict constraints on the form of the effective Lagrangian. We identify a topological term in the Lagrangian that couples superfluid and crystalline modes. For small superfluid fractions, this interaction term is dominant in problems involving defects. As an illustration, we compute the differential cross section of scatterings of low-energy transverse elastic phonons by a superfluid vortex. The result is model independent.     

Application of atomic absorption spectrometry for the quantitative determination of metallic impurities in pure uranium compounds.

Several elements (V, Mo, Fe, Mn, Cd, Zn) as metallic impurities in pure uranium compounds were quantitatively determined by atomic absorption spectrometry. The effects of uranium and that of other factors on the absorption intensity of each element were studied. The analyzed samples were dissolved in 6 M nitric acid, and uranium was selectively extracted with tributylphosphate. The aqueous solution containing impurities was then evaporated and the obtained moist residues were dissolved in dilute hydrochloride acid or nitric acid. The sample solution was measured with a flame atomic absorption spectrometer under the optimum conditions, such as the maximum wavelength, suitable ratio of acetylene-air or acetylene-nitrogen oxide mixture, and some other parameters of the instrument. The analytical procedure was applied in laboratories belonging to Vietnam Atomic Energy Commission for the determination of these above-mentioned elements in synthesized uranium samples and in purified uranium oxide samples with high precision and accuracy.     

柱胞鱼腥藻（Anabaena cylindrica）原生质球培养再生的初步研究

柱胞鱼腥藻（Ａｎａｂａｅｎａｃｙｌｉｎｄｒｉｃａ）原生质球培养再生的初步研究郭厚良，宋文贞，于登洲（武汉大学生命科学学院，武汉，４３００７２）陈贤均（咸宁医学院生物学教研室）关键词蓝藻，原生质球，培养，再生中图法分类号Ｑ９４９．２２１９６７年，Ｂｉｇ...     

Preparation and photoelectronic properties of the system Cd2Ge1−xSixO4

Members of the system Cd₂Ge_1?xSi_xO₄ where 0 ≤ x ≤ 0.4 have been prepared. These compounds were observed to crystallize with the olivine structure, space group Pbnm. The resistivity, Hall mobility, flat-band potential, band gaps, and stability were determined as functions of composition. The variation of these photoelectronic properties can be attributed to the reduction of the cell parameters with increasing silicon substitution. The substitution of silicon for germanium reduces the loss of photocurrent from 25% after 1 hr for x = 0.0 to only 6% after 22 hr for x = 0.4.     

Overcoordinated hydrogens in the carbon vacancy: donor centers of SiC

Epitaxial silicon carbide is likely to contain hydrogen and vacancies ( V); therefore, V+nH complexes are likely to influence its electronic properties. Using ab initio calculations we show that neutral and positive H atoms are trapped by carbon vacancies ( V(C)) in three-center bonds with two Si neighbors. The double positive charge state of V(C)+H is not stable in equilibrium and in the triply positive state H binds only to one of the Si neighbors. At most two H atoms can be accommodated by a single V(C). The V(C)+nH complexes have donor character and exhibit rather atypical vibration modes for Si-H bonds. Occupation levels and spin distributions were calculated and compared for V(C)+H and V(C).     

Catalytic asymmetric synthesis of cyclopentenones from propargyl malonates and allylic acetate by successive action of homogeneous palladium(II) and cobalt on charcoal catalysts in a one-pot reaction

The tandem action of a homogeneous chiral Pd(II) catalyst and a heterogeneous Co/C catalyst leads to a two-step one-pot highly enantioselective Pauson-Khand-type reaction.