Production cross-section of Ra-230 in the reaction of 60 MeV/u O-18 ions with U-238

A thick natural uranium target was bombarded with a 60 MeV/u O-18 beam. The neutron-rich isotope Ra-230 as the target residue was produced through the multinucleon transfer reaction (U-238-4p-4n). The barium and radium fraction as BaCl2 precipitate were radiochemically separated first from the mixture of uranium and reaction products. Then, the radium fraction was separated from BaCl2 precipitate by using cation exchange technique. The gamma-ray spectra of the Ra fraction were measured using an HPGe detector. The production cross sections of Ra-230 were obtained by a combination of the radiochemical separation technique and off-line gamma-ray spectroscopy. The cross section of Ra-230 has been determined to be 66 +/- 20 mu b.

Study of a high power density sodium polysulfide/bromine energy storage cell

Nickel catalyst supported on carbon was made by reduction of nickelous nitrate with hydrogen at high temperature. Ni/ C catalyst characterization was carried out by XRD. It was found that the crystal phase of NiS and NiS2 appeared in the impregnated catalyst. Ni/ C and Pt/ C catalysts gave high performance as the positive and negative electrodes of a sodium polysulfide/ bromine energy storage cell, respectively. The overpotentials of the positive and negative electrodes were investigated. The effect of the electrocatalyst loading and operating temperature on the charge and discharge performance of the cell was investigated. A power density of up to 0.64 W cm(-2) ( V = 1.07 V) was obtained in this energy storage cell. A cell potential efficiency of up to 88.2% was obtained when both charge and discharge current densities were 0.1 A cm(-2).

土壤持水特征测定中质量含水量、吸力和容重三者间定量关系I.填装土壤

在试验过程中,通常采用一个土样进行连续试验来测定土壤的持水特征。此时,土样的有机质、黏粒矿物类型和阳离子交换量等性质基本保持不变,而土壤的容重在水力学和机械压力共同作用下会发生很大的变化。因此,我们认为实测的土壤持水特征不再是土壤吸力和含水量相对应的一条曲线,而是由土壤质量含水量、吸力和容重三变量共同确定的一个曲面。本文在Brooks-Corey土壤水分特征曲线模型的基础上,提出了两种描述土壤质量含水量、吸力和容重三变量关系的曲面模型,分析了模型的优缺点和适用条件,并采用离心机石蜡控容重法实测了四种质地填装土壤的三变量特征曲面。研究结果表明:土壤持水特征是由土壤质量含水量、吸力和容重三变量共同确定的一个曲面这一假设是合理的;类似于Brooks-Corey模型的两种幂函数经验曲面模型能够合理地描述填装土壤的实测数据,决定系数均大于0.94;模型Ⅰ的拟合效果略好于模型Ⅱ,但模型Ⅱ包含两个物理意义明确的参数,具有一定的优势。这一研究将为校正容重变化对土壤水力学参数的影响提供新的途径。

Combining chemical reduction with an electrochemical technique for the simultaneous detection of Cr(VI), Pb(II) and Cd(II)

This work herein reports the approach for the simultaneous determination of heavy metal ions including cadmium (Cd(II)), lead (Pb(II)), and chromium (Cr(VI)) using a bismuth film electrode (BFE) by anodic stripping voltammertry (ASV). The BFE used was plated in situ. Due to the reduction of Cr(VI) with H2O2 in the acid medium, on one hand, the Cr(III) was produced and Cr(VI) was indirectly detected by monitoring the content of Cr(III) using square-wave ASV. On the other hand, Pb(II) was also released from the complex between Pb(II) and Cr(VI). Furthermore, the coexistence of the Cd(II) was also simultaneously detected with Pb(II) and Cr(VI) in this system as a result of the formation of an alloy with Bi. The detection limits of this method were 1.39 ppb for Cd(II), 2.47 ppb for Pb(II) and 5.27 ppb for Cr(VI) with a preconcentration time of 120 s under optimal conditions (S/N = 3), respectively. Furthermore, the sensitivity of this method can be improved by controlling the deposition time or by using a cation-exchange polymer (such as Nafion) modified electrode.

Narion/Poly(sodium 4-styrenesulfonate) mixed coating modified bismuth film electrode for the determination of trace metals by anodic stripping voltammetry

To improve the reproducibility, stability, and sensitivity of bismuth film electrode (BiFE), we studied the performances of a mixed coating of two cation-exchange polymers, Nafion (NA) and poly(sodium 4-styrenesulfonate) (PSS), modified glassy carbon BiFE (GC/NA-PSS/BiFE). The characteristics of GC/NA-PSS/BiFE were investigated by scanning electron microscopy and cyclic voltammetry. Various parameters were studied in terms of their effect on the anodic stripping voltarnmetry (ASV) signals. Under optimized conditions, the limits of detection were 71 ng L-1 for Cd(II) and 93 ng L-1 for Pb(II) with a 10 min preconcentration. The results exhibited that GC/NA-PSS/BiFE can be a reproducible and robust toot for monitor of trace metals by ASV rapidly and environmentally friendly, even in the presence of surface-active compounds.

Separation of scandium(III) from lanthanides(III) with room temperature ionic liquid based extraction containing Cyanex 925

The separation of Sc(III) from Y(III), La(III) and Yb(III) in [C(8)mim][PF6] containing Cyanex 925 has been investigated, and is reported in this paper. A cation exchange mechanism of Sc(III) in [C(8)mim][PF6] and Cyanex 925 is proposed by study of the influence of anionic and cationic species on the extraction. The coefficient of the equilibrium equation of Sc(III) was confirmed by slope analysis of log D-Sc vs log [Cyanex 925], and the loading capacity also confirmed the stoichiometry of Cyanex 925 to Sc(III) was close to 3:1. Infrared data for Cyanex 925 saturated with Sc(III) in [C(8)mim][PF6] indicated strong interaction between P=O of Cyanex 925 and Sc(III). In addition, the relationship between log D-Sc and temperature showed that temperature had little influence on the extraction process, and the resulting thermodynamic parameters indicated that an exothermic process was involved.

Synergistic extraction of rare earths by mixture of bis(2,4,4-trimethylpentyl)phosphinic acid and Sec-nonylphenoxy acetic acid

Synergistic extraction of trivalent rare earths (RE=Sc, Y, La, Gd, Yb) from hydrochloride medium using mixture of bis(2,4,4-trimethylpentyl)phosphinic acid (HL, Cyanex272) and Sec-nonylphenoxy acetic acid (HA, CA-100) in n-heptane has been studied. The synergistic enhancement coefficients were observed for La (1.30), Gd (1.97), Y (3.59), Yb (8.21) and Sc (14.41). The results indicated yttrium was extracted into n-heptane as YH(5)A(4)L(4) mixed species instead of Y(HL2)(3), Y(OH)(2)A(HA)(3) which were extracted by Cyanex272 and CA-100, respectively. A cation exchange mechanism was proposed and further clarified by IR spectra. The equilibrium constants, formation constants and thermodynamic functions such as Delta G, Delta H and Delta S were determined. The Cyanex272 + CA-100 system not only enhanced the extraction efficiency of RE but also improved the selectivities significantly. The mutual separation factors of these ions suggested the mixture system would be of practical value in extraction and separation of rare earths.

Relationship between the continually expanded interlayer distance of layered silicates and excess intercalation of cationic surfactants

Excess intercalation of cationic surfactants into Na-montmorillonites (MMTs) was investigated in organically modified silicates (OMSs), synthesized with MMTs and octadecylammonium chloride (OAC) by systematically varying the surfactant loading level from 0.625 to 1, 1.25, 1.56, 2, and 2.5 with respect to the cation exchange capacity (CEC) of MMTs. Wide-angle X-ray diffraction and thermogravimetric analysis results indicated that the continuous increase of interlayer distances came from the entering of surfactants into the interlayer of MMTs. Excess surfactants were extracted with a Soxhlet apparatus, which showed two kinds of intercalation states of surfactants in the interlayer when the surfactant loading level was beyond the CEC. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to explore the microstructures of OMSs. It was found that the surfactants arranged more orderly as the loading level increased and the excess surfactants piled up in the interlayer together with counterions, forming a sandwiched surfactant layer. On the basis of the results, the layer structures of OMSs and the mechanism by which the surfactants entered the interlayer were expounded: surfactant cations entered the interlayer through cation exchange reactions and were tightly attracted to the silicate platelet surfaces when the surfactant loading level was below the CEC;

Effects of surfactant loadings on the dispersion of clays in maleated polypropylene

A series of organically modified clays (OMCs) with a surfactant loading range from 0.625 to 2.5 times the cation exchange capacity (CEC) were melt-mixed with maleated polypropylene (PPMA). Wide-angle X-ray diffraction and transmission electron microscopy results of these narrocomposites show that dispersion of clays becomes unfavorable in the PPMA matrix during melt intercalation as the surfactant loading increases in the process of modifying clays, though larger interlayer distances are obtained in their corresponding OMCs. It is even important that clays uniformly disperse at the nanoscale level in the PPMA matrix when the surfactant loadings are below the CEC, which implies that incomplete exchange of inorganic cations in the process of modifying clay benefits the dispersion of clays in the PPMA matrix.

Functionalized inorganic-organic composite material derivated by sol-gel for construction of mediated amperometric hydrogen peroxide biosensor

A novel functionalized inorganic-organic hybrid material with cation exchange property was prepared by sol-gel method. The H2O2 biosensor was fabricated by simply dipping the horseradish peroxidase-containing functionalized membrane modified electrode into Meldola's blue (MDB) solution. MDB was adsorbed and firmly immobilized within the membrane. The electrochemical behavior of MDB incorporated in the membrane was more reversible compared with that of the solution species and suitable as mediator for the horseradish peroxidase. The response time was less than 25 s. Linear range is up to 0.6 mM (COH. coeff. 0.9998) with detection Limit of 9 x 10(-7) M. High sensitivity of 75 nA mu M cm(-2) was obtained due to high MDB-loading. The biosensor exhibited a good stability. (C) 1999 Elsevier Science B.V. All rights reserved.

High level expression, purification, and characterization of the shrimp antimicrobial peptide, Ch-penaeidin, in Pichia pastoris

Penaeidins, members of a new family of antimicrobial peptides constitutively produced and stored in the haemocytes of penaeid shrimp, display antimicrobial activity against bacteria, and fungi. Here, a DNA sequence encoding the mature Ch-penaeidin peptide was cloned into the pPIC9K vector and transformed into Pichia pastoris. The transformed cells were screened for multi-copy plasmids using increasing concentrations of G418. Positive colonies carrying chromosomal integrations of the Chp gene were identified by phenotype and PCR. When transformed cells were induced with methanol, SDS-PAGE and Western blotting revealed the production of a similar to6100 Da recombinant CHP (rCHP) expression product. Large scale expression revealed that rCHP was produced at 108 mg/L under optimal conditions in the highest Chp-producing P. pastoris clone. The antimicrobial activities of rCHP were studied by liquid phase analysis, which revealed that rCHP exhibited activities against some Gram-negative and Gram-positive bacteria, but had a relatively low activity against some fungi. Purification of rCHP by cation exchange chromatography and subsequent automated amino acid sequencing revealed the presence of four additional amino acids (YVEF) at the N-terminus that belonged to the cleaved fusion signal peptide; these residues may account for the observed decrease in antifungal activity. Together, these observations indicate that rCHP is an effective antimicrobial peptide that can be successfully produced at high levels in the yeast, and therefore may be a potential antimicrobial candidate for practical use. (C) 2004 Elsevier Inc. All rights reserved.

东海榴辉岩向斜长角闪岩的转化过程

The Ultrahigh Pressure Metamorphic (UHPM) eclogite, which was resulted from deep subduction of crustal continent, is very significant due to its continental dynamic implications. Further more, this kind of rocks experienced great P-T, fluid and stresses changes during its forming and exhumation, causing mineral reactions occur intensively, which resulted in a lot of fantastic micro-texture. The micro-texture was preserved duo to a rapid exhumation of the eclogite. This PhD dissertation takes such micro-textures in 10 Donghai eclogite samples South Sulu UHPM terrene, as research object to reveal the transformation of the eclogite to amphibolite. Microscope and Scanning Electron Microscope were employed to observe the micro-texture. Basing on microprobe analysis of minerals, the ACF projections and iso-con analysis were used to uncover the mineral reactions during the transformation. Micro-texture observation (both of Microcopy and Electron Scanning Microscope), demonstrated: l.The peak mineral assemblage of the researched Donghai eclogites is garnet + omphacite + rutile (+ kyanite + aptite +coesite). 2.The transformation of the Donghai eclogite to amphibolite can be divided into two stages: The earlier one is Symplectization, resulting in the forming of diopside + albite (+magnetite) symplectite that occurred only along the boundary between two adjacent omphacite grains. Other minerals were not involved in such reaction. The latter stage is Fluid-Infiltration of the eclogite, which was caused by fluid-intrusion. The infiltration is demonstrated by amphibolization of the symplectite, decomposition of garnet and the forming of some hydrous minerals such as phengite and epidote, and resulted in an amphibole + plagioclase + phengite + epidote or ziosite assemblage. Basing on microprobe analysis of the minerals, ACF projections indicated: In the ACF diagrams, the two joint lines of peak Grt + Omp and Dio + Ab crossed at Omp projection-point, indicating that the garnet had not taken part in the forming reaction of the Dio + Ab symplectite, just like that had been pointed out by micro-texture observation. In the ACF diagrams, the hornblende + plagioclase + epidote + phengite quadrilateral intersected with Dio + Ab + Grt triangle, demonstrating that the hydrous mineral assemblage was formed by fluid infiltration through garnet, diopside and albite. Iso-con (mass-balance) analysis of the symplectization and infiltration reveals: 1.The symplectization of the omphacite has a very complex mass exchange: Some symplectite gained only silicon from its surroundings; and some one requires Ca, but provides Na to its surroundings; while other symplectite provides Ca, Mg and Fe to its surroundings. 2.The infiltration cause variable mass exchanges occurring among the garnet, diopside and albite: In some eclogite sample, no mass, except H2O, exchange occurred during the infiltration. Meanwhile, there was not any hydrous mineral except hornblende formed in the sample accordingly. In some samples, the mass exchange among the three minerals is complex: amphibolization of the diopside in a symplectite gained Al from garnet, and provided Si and Ca to its surrounding, resulting in a Si, Ca and Al-rich fluid. Correspondingly, there was a lot of phengite and ziosite occurred in the sample. In other samples, the amphibolization of a symplectite provided Fe and Mg besides Si and Ca to its surrounding while gained Al. In such kind of sample, epidote occurred within the hydrous mineral assemblage. Synthesizing the micro-texture observation, ACF analysis and iso-con analysis, we deduced the transformation procedure as following: 1. A symplectite after an omphacite was resulted by one, or two, or all of following mineral reactions together: Jd (Ca-Tsch) +SiO2=Ab (An) (1) 4NaA IS i.A+CaO=2NaAlS i308+Na20+CaAl2S 1208 (2) 2NaAlSi2OB (Jd in Omp)+CaMgSi;,0B(Dio in Omp)-2NaAlSi:,O"(Ab)+Ca0+Mg0 (3) 2(CaAl2Si0fi) (Ca-tsch in Omp)+CaFeSi2O6(Hed in 0mp)-H>2CaAl2Si208(An)+Ca0 + FeO (4) A CO2-rich fluid is suggested as cataclysm for the above reactions, which largely increased the mobility of Ca, Mg and Na resulted from reaction (2), (3) and (4). The immobile product Fe2* combined with rutile to form ilmenite, resulting in rutile + ilmenite symplectite. Or, the Fe was precipitated as hematite locally. A procedure of the fluid infiltration as following is suggested: I .A hydrous fluid intruded into the eclogite, and reacted first with garnet to form hornblende and extra Al, resulting in a hornblende film around the garnet grain and an Al-rich fluid. 2.The Al-rich fluid infiltrated through the symplectite, OH" and part of the Al in the fluid combined with Dio while some Si and Ca in the Dio were dissolved made the Dio transferred to amphibole. Meanwhile, plagioclase-type cation exchange occurred between the fluid and plagioclase in the symplectite, making the plagioclase have a higher An-content. 3.Above infiltration and cation exchange resulted in an Al, Si, Ca (and K, providing the primary hydrous fluid contain K)-rich fluid. 4.Under suitable conditions, the solute in the fluid precipitated to form phengite firstly. After the K element in the fluid was consumed up, ziosite or epidote was formed. If the fluid did not contain any K. element, only ziosite or epidote was precipitated. For those eclogites, where all omphacite had been replaced by symplectite before infiltration, neither element exchange occurred, nor did phengite or epidote form during the infiltration. At the last stage, the garnet was oxidized and breakdown: garnet + H2O = epidote + hornblende + hematite, due to more and more fluid intruding into the eclogite. At this time, all the peak minerals were replaced by amphibolite-phase ones, and the eclogite transformed to an amphibolite completely. Tentative pressure calculation indicates that the infiltration occurred at 3-6kbar (about 10-20km depth), where the deformation mechanics transformed from brittle to ductile yield. At such depth, the surface water can permeate the rocks through fault system, causing a rapid cooling.

准噶尔盆地低阻油藏实验研究及储层评价方法

Low resistivity reservoir is a special reservoir which is different from normal reservoir in identification and evaluation.Through core experiment and analysis, the achievement of which resistivity is resulted from clay additive electric conductivities and high bound water saturation in Junggar basin is gained. For accurately evaluating low resistivity, a good many of experiment have been completed, such as resistivity index and formation factor in hi^jher temperature and higher pressure, semi-permeability board, cation exchange, bound water, NMR (nucleus magnetism response), non-Nad water in different temperature and salinity, the experiments result show that lower resistivity has complex relation with these electric-parameters and chloric ion content in non-NaCl water.Based on comprehensive interpretation of NMR and normal resistivity data, the volume of moved water, bound water, moved oil and residual oil in the strata can be determined quantitatively and which have significant influence on reservoir recognition and perforation optimized.Experiment data (SEM mold, thin section, X ray diffraction, mercury penetration) can be used to analysis low resistivity forming and the relation between low resistivity and pore texture, to set up relation between porosity, permeability and petrophysical property. The reservoir was sorted, evaluated and described. The oil bedding in southern margin of Junggar basin is low porosity, low resistivity reservoir.Based on invasion theory of electric well-logging, modelling and inversion of resistivity well-logging are accomplished. For enhancing low resistivity resulted from higher bound water saturation and cation exchange, invasion period, invasion radius, the relation between fluid distribution in pore and response of laterolog logging have been studied. Virgin zone resistivity, invasion zone resistivity and invasion radius were inversed and which enhanced evaluation accuracy of reservoir. The method was used to process well-logging data in Luliang oilfield and southern margin in Junggar basin, and reservoir resistivity was enhanced effectively, appropriate oil saturation gained and it has better effect on oil exploration.

Human plasma proteome analysis by multidimensional chromatography prefractionation and linear ion trap mass spectrometry identification

A resurgence of interest in the human plasma proteome has occurred in recent years because it holds great promise of revolution in disease diagnosis and therapeutic monitoring. As one of the most powerful separation techniques, multidimensional liquid chromatography has attracted extensive attention, but most published works have focused on the fractionation of tryptic peptides. In this study, proteins from human plasma were prefractionated by online sequential strong cation exchange chromatography and reversed-phase chromatography. The resulting 30 samples were individually digested by trypsin, and analyzed by capillary reversed-phase liquid chromatography coupled with linear ion trap mass spectrometry. After meeting stringent criteria, a total of 1292 distinct proteins were successfully identified in our work, among which, some proteins known to be present in serum in < 10 ng/mL were detected. Compared with other works in published literatures, this analysis offered a more full-scale list of the plasma proteome. Considering our strategy allows high throughput of protein identification in serum, the prefractionation of proteins before MS analysis is a simple and effective method to facilitate human plasma proteome research.

Electrochromatographic evaluation of a silica monolith capillary column for separation of basic pharmaceuticals

A silica-based monolithic capillary column was prepared via a sol-gel process. The continuous skeleton and large through-pore structure were characterized by scanning electron microscopy (SEM). The native silica monolith has been successfully employed in the electrochromatographic separation of beta-blockers and alkaloids extracted from traditional Chinese medicines (TCMs). Column efficiencies greater than 250000 plates/m for capillary electrochromatography (CEC) separation of basic compounds were obtained. It was observed that retention of basic pharmaceuticals on the silica monolith was mainly contributed by a cation-exchange mechanism. Other retention mechanisms including reversed-phase and normal-phase mechanisms and electrophoresis of basic compounds also played a role in separation. A comparison of the differences between CEC and capillary zone electrophoresis (CZE) separation was also discussed.