Selective separation of yttrium by CA-100 in the presence of a complexing agent

The selective separation of Y from yttrium solution containing small heavy rare earth (HRE) impurities (Ho, Er, Tm, Yb, Lu) by liquid-liquid extraction using CA-100 in the presence of a water-soluble complexing agent of ethylenediaminetetraacetic acid (EDTA) was experimentally studied at 298K. Experiments were carried Out in two feeds, Feed-I: [RE](f) = 4.94 x 10(-3) M, Y = 98.5%, HRE (Ho, Er, Tm, Yb, Lu) = 1.5%; Feed-II: [RE](f) = 4.94 x 10(-3) M, Y = 99.9%, HRE (Ho, Er, Tm, Yb, Lu) = 0.1%, as a function of equilibrium pH (pH(eq)), the concentration ratio of [EDTA]:[HRE impurities]. It was shown that the extraction of HRE in the presence of EDTA was suppressed when compared to that of Y because of the masking effect, while the selective extraction of Y was enhanced and the separation factors increased to maximum at appropriate condition for Feed-I: Y/Ho = 1.53, Y/Er = 3.09, Y/Tm = 5.61, Y/Yb = 12.04, Y/Lu = 27.51 at pH 4.37 and [EDTA]:[HRE impurities] = 4: 1, for Feed-II: Y/Ho = 1.32, Y/Er = 1.91, Y/Tm = 2.00, Y/Yb = 3.05, Y/Lu = 3.33 at pH 4.42 and [EDTA]: [HRE impurities] = 8:1. The separation and purification of Y by this method was discussed.

Computer simulation for effect of Pr(III) on Ca(II) speciation in human interstitial fluid

A multiphase model of metal ion speciation in human interstitial fluid was constructed and the effect of Pr(III) on Ca(II) speciation was studied. Results show that free Ca2+, [Ca(HCO3)], and [Ca(Lac)] are the main species of Ca(II). Because of the competition of Pr(III) for ligands with Ca(II), the percentages of free Ca2+, [Ca(Lac)], and [Ca(His)(Thr)H-3] increase gradually and the percentages of CaHPO4(aq) and [Ca(Cit)(His)H-2] decrease gradually with the increase in the total concentration of Pr(III). However, the percentages of [Ca(HCO3)] and CaCO3(aq) first increase and then begin to decrease when the total concentration of Pr(III) exceeds 6.070 x 10(-4) M.

STUDIES ON THE COORDINATION OF TB(III) AND CA(III) WITH AMINO-ACID UNDER THE PHYSIOLOGICAL CONDITION

Tb(Ca)-glycine, Tb(Ca)-alanine, Tb(Ca)-glycine-alanine systems were studied by potentiometry (37%, I = 0.15 mol/L NaCl). The stability constants of complexes and distribution of species in ternary system were obtained. The results show Ca<Tb for the stability of binary complexes, Ca>Tb for the ternary complexes. The species convert each other with changing pH values.

NaCl/Ca/Al as an efficient cathode in organic light-emitting devices

An efficient cathode NaCl/Ca/Al used to improve the performance of organic light-emitting devices (OLEDs) was reported. Standard NM-bis(1-naphthyl)-NAP-diphenyl-1,1' biphenyl 4,4'-dimaine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq(3)) devices with NaCl/Ca/Al cathode showed dramatically enhanced electroluminescent (EL) efficiency. A power efficiency of 4.6 lm/W was obtained for OLEDs with 2 nm of NaCl and 10 nm of Ca, which is much higher than 2.0 lm/W, 3.1 lm/W, 2.1 lm/ W and 3.6 lm/W in devices using, respectively, the LiF (1 nm)/Al, LiF (1 nm)/Ca (10 nm)/Al, Ca (10 nm)/Al and NaCl (2 nm)/ Al cathodes. The investigation of the electron injection in electron-only devices indicates that the utilization of the NaCl/Ca/Al cathode substantially enhances the electron injection current, which in case of OLEDs leads to the improvement of the brightness and efficiency.

Evaluation of bond covalency and bond valence in Sr-doped perovskite-type compounds

Formulas for decomposing of complex crystals to a sum of binary crystals are described and applied to the study of bond covalency in La1-xSrxFeO3 (0.0 less than or equal to x less than or equal to 0.9) and Ca1-xSrxMnO3 (0.0 less than or equal to x less than or equal to 0.5). The bond valence is treated by bond-valence sums scheme. The results indicate that, for both compounds, with the increasing doping level, the bond covalency and bond valence show the same trend, namely, larger bond covalency corresponds to higher bond valence. For La1-xSrxFeO3, with the increase of doping level, the bond covalency of La-O, Ca-O decreases in the orthorhombic (0.0 less than or equal to x less than or equal to 0.2) and rhombohedral (0.4 less than or equal to x less than or equal to 0.7) systems, then increases slightly for the cubic (0.8 less than or equal to x less than or equal to 0.9) system, but that of Fe-O increases for all crystal systems. A sharp decrease in bond covalency was observed where the crystal changes from orthorhombic to rhombohedral, while a smooth trend was seen for the rhombohedral-to-cubic transition. On the other hand, for orthorhombic Ca1-xSrxMnO3, the bond covalency of Ca-O, Sr-O, and Mn-O (4-coordinate site) decreases with the increasing doping level, that of Mn-O (2-coordinate site) increases.

甲烷团簇纯库仑爆炸的离子平均动能

利用一简单的经典静电模型研究了甲烷团簇纯库仑爆炸情况下产生的离子平均动能。研究表明，甲烷团簇爆炸后离子获得的平均动能和离子的初始平均静电势能的比值，与团簇的尺寸大小无关。这意味着在甲烷团簇纯库仑爆炸近似下，不必使用分子动力学模拟，离子获得的动能可以通过这一比值以及离子的初始静电势能进行估算。给出了不同碳离子价态下的离子平均动能和其初始平均静电势能的比值。

Photosynthetic utilization of inorganic carbon in the economic brown alga, Hizikia Fusiforme (Sargassaceae) from the South China Sea

The mechanism of inorganic carbon (C-i) acquisition by the economic brown macroalga, Hizikia fusiforme (Harv.) Okamura (Sargassaceae), was investigated to characterize its photosynthetic physiology. Both intracellular and extracellular carbonic anhydrase (CA) were detected, with the external CA activity accounting for about 5% of the total. Hizikia fusiforme showed higher rates of photosynthetic oxygen evolution at alkaline pH than those theoretically derived from the rates of uncatalyzed CO2 production from bicarbonate and exhibited a high pH compensation point (pH 9.66). The external CA inhibitor, acetazolamide, significantly depressed the photosynthetic oxygen evolution, whereas the anion-exchanger inhibitor 4,4'-diisothiocyano-stilbene-2,2'-disulfonate had no inhibitory effect on it, implying the alga was capable of using HCO3- as a source of C-i for its photosynthesis via the mediation of the external CA. CO2 concentrations in the culture media affected its photosynthetic properties. A high level of CO2 (10,000 ppmv) resulted in a decrease in the external CA activity; however, a low CO2 level (20 ppmv) led to no changes in the external CA activity but raised the intracellular CA activity. Parallel to the reduction in the external CA activity at the high CO2 was a reduction in the photosynthetic CO2 affinity. Decreased activity of the external CA in the high CO2 grown samples led to reduced sensitiveness of photosynthesis to the addition of acetazolamide at alkaline pH. It was clearly indicated that H. fusiforme, which showed CO2-limited photosynthesis with the half-saturating concentration of C-i exceeding that of seawater, did not operate active HCO3- uptake but used it via the extracellular CA for its photosynthetic carbon fixation.

Luminescence properties of ZnSe films grown by hot wall epitaxy

The photoluminescence (PL) properties of ZnSe films grown by hot wall epitaxy are reported. The PL spectra show clear neutral donor-bound exciton peak; donor acceptor pair (DAP) peak, conduction band to acceptor (CA) peak, and their phonon replicas until fourth order. The conduction band to acceptor peak and it's phonon replicas exist until room temperature. From the ratio of PL intensities of DAP and CA peaks and their replicas, we obtain the Huang-Rhys factor S = 0.58, in agreement with other experiments for acceptor-bound exciton transitions. From the temperature dependence of PL intensities we derive the activation energy of thermal quenching process for the DAP transitions as about 7 meV.

Isotopic dependence of production cross sections of superheavy nuclei in hot fusion reactions

The dinuclear system model has been further developed by introducing the barrier distribution function method in the process of heavy-ion capture and fusion to synthesize superheavy nuclei. The capture of two colliding nuclei, formation and de-excitation process of compound nucleus are decribed by using empirical coupled channel model, solving master equation numerically and statistical evaporation model, respectively. Within the framework of the dinuclear system model, the fusion-evaporation excitation functions of the systems Ca-48(Am-243, 3n-5n) (288-286)115 and Ca-48(Cm-248, 3n-5n)(293-291)116 are calculated, which are used for synthesizing new superheavy nuclei at Dubna in recent years. Isotopic dependence of production cross sections with double magic nucleus Ca-48 bombarding actinide targets U, Np, Pu, Am, Cm to synthesize superheavy nuclei with charged numbers Z=112-116 is analyzed systematically. Based on these analysis, the optimal projectile-target combination and the optimal excitation energy are proposed. It is shown that shell correction energy and neutron separation energy will play an important role on the isotopic dependence of production cross sections of superheavy nuclei.