bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamics of extraction of Am(III) and Eu(III) from different anionic media with Tri-n-octyl phosphine oxide
Authors: Suresh G. , Murali M. S. , Mathur J. N.
Published: December 2003

Extraction of Am(III) and Eu(III) from NO3
-, ClO4
-, SCN- and NO3
- + ClO4
- media with tri-n-octyl phosphine oxide (TOPO) in xylene has been carried out at 15, 25, 30 and 35°C. Under the extraction conditions the species M(NO3)3·3TOPO, M(SCN)3·4TOPO, M(ClO4)3·4TOPO and MNO3(ClO4)2·4TOPO are predominantly extracted at all the temperatures (M=Am or Eu). The two phase equilibrium constant (log K
ex) follows an order SCN- > NO3
- + ClO4
- > ClO4
-> NO3
-. Extraction enthalpies have been calculated in each system from the temperature dependence of the K
ex. The thermodynamic parameters ΔG, ΔH and ΔS have been discussed and compared with other mono- and bidentate organophosphorus extractants for Am(III) and Eu(III) from same aqueous medium. The -ΔH values for the two-phase reaction follow an order NO3
- + ClO4
- > ClO4
- > SCN- > NO3
- for both metal ions. This has been explained on the basis of heat energies involved with the formation of ML3 complex (L being the anion used), the transfer of ML3 to the organic phase and the attachment of TOPO molecules, and also on the limiting partial molal volume of the anions.
Influence of humic acid size on actinide complexation
Authors: Monsallier Jean-Marc , Choppin Gregory R.
Published: December 2003

The complexation of Am(III) and Eu(III) with humic acid of different molecular sizes was measured and the data for the ≥300kD and ≥10kD sized HA at pcH 4.0 and 6.0 was analyzed by the Charge Neutralization Model (CNM) and the Polyelectrolyte Model (PM). For the PM, solvent extraction was used to obtain the stability constants of 241Am at tracer concentration. For the CNM, ultrafiltration was used to determine the loading capacity and the stability constants for Eu(III) at macro concentrations. There was a difference of 1-2 orders of magnitude in the stability constants from the two models. The 5
D
0–7
F
0 excitation spectra of Eu(III) as a function of loading of HA was found to have a shift in wavenumbers of the peak maximum, indicating that the coordination environment of Eu(III) varied with pH, presumably due to variation in the number of functional groups of the humate bound to the metal ion.
The role of oxidants in Pu-Th separation studies employing di(2-ethylhexyl)isobutyramide (D2EHIBA) as extractant
Authors: Pathak P.N. , Prabhu D. R. , Manchanda V. K.
Published: December 2003

Distribution studies of Pu and Th have been carried out under varying acidity/ligand concentrations to optimise the conditions for their separation employing di(2-ethylhexyl)isobutyramide (D2EHIBA) in n-dodecane as extractant. In view of the selective complexation of D2EHIBA towards hexavalent metal ions over tetravalent metal ions, the focus of the present work is to identify a suitable oxidant of Pu. Amongst various oxidising agents investigated for the oxidation of Pu to Pu(VI), AgO appears to be a promising candidate as (i) it is thermodynamically as well as kinetically a favourable oxidant and (ii) unlike Cr(VI) and Ce(IV), it is not co-extracted with Pu towards the organic phase.
Synthesis and properties of neptunium(VI,V) and plutonium(VI) pertechnetates
Authors: Fedosseev A. M. , Budantseva N. A. , Grigoriev M. S. , Guerman K. E. , Krupa J.-C.
Published: December 2003

Preparation, crystal structure and properties revealed through IR and visible absorption spectroscopy study of Np(V,VI), Pu(VI) compounds formed with pertechnetate anions are reported. Spectrophotometric study of Np(V) and Pu(VI) in NH4TcO4 aqueous solutions (TcO4
- concentration ranging between 0.2-0.5 M) shows only a slight interaction of NpO2
+ and PuO2
2+-ions with pertechnetate oxoanions in solution. On the contrary, for Np(V), Np(VI) and Pu(VI) pertechnetates in solid state, changes in the spectra clearly evidence the coordination of the actinides(V,VI) with TcO4
--anions. That is in agreement with Np(VI) pertechnetate X-ray structural analysis performed on a single crystal.
Speciation of polonium released from molten lead bismuth
Authors: Buongiorno J. , Larson C. , Czerwinski K.R.
Published: December 2003

The alpha-emitter 210Po is an activation product of liquid lead-bismuth, a low melting eutectic under investigation as a coolant of the next generation fast nuclear reactors. Experiments were performed to measure the gaseous polonium chemical species for assessing the radioactivity release from a Pb-Bi bath upon contact with a gas stream. The vapor pressure of lead polonide was measured over the 400-550°C temperature range and found to be in agreement with an existing correlation derived from data at higher temperatures. Also, it was experimentally confirmed that the presence of steam in the gas stream above the Pb-Bi melt substantially increases the amount of polonium released due to the formation of the volatile compound H2Po. The free-energy variation of the H2Po formation reaction was determined, permitting the calculation of the Po gas phase speciation under the experimental conditions.
Extraction separation of No-carrier-added astatine from bismuth target
Authors: Nayak D. , Lahiri S.
Published: December 2003

Alpha particle activation of natural Bi2O3results in the formation of astatine radionuclides. A simple and rapid separation method of astatine is presented from the bulk target matrix bismuth by employing liquid-liquid extraction (LLX) method using methylisobutylketone (MIBK) and hydrochloric acid. Back extraction of astatine was performed by ethylenediaminetetraacetic acid (EDTA) solution at pH 10.
Influence of surface charge of an Fe-oxide and an organic matter dominated soil on iodide and pertechnetate sorption
Authors: Kaplan D. I.
Published: December 2003

Iodine-129 and technecium-99 are commonly the largest contributors to the calculated health risk associated with long-term nuclear-waste burial. The high proportion of risk from these radionuclides is due to their large inventories in many types of waste, long half-lives, and the perception that they are highly mobile in sediments. In most aquifer systems, these radionuclides exist as anions, iodide (I-) and pertechnetate (TcO4
-), and sorb poorly to soils that possess a net negative charge. A series of iodide and pertechnetate sorption experiments were conducted over a pH range of 3 to 9. The two soils used in this study possessed a pH-dependent charge; one soil was collected from a wetland and derived most of its charge from organic matter, whereas the second soil was collected from an upland site and derived most of its charge from Fe/Al-oxide coatings. Although both soils had nearly identical particle size distributions, pH values, and mineral compositions, they had dissimilar surface charge and I- and TcO4
- sorption behavior. The pH where the wetland soil did not have any net charge (more specifically, the Point-of-Zero-Salt Effect) was 4.4. The pH where the upland soil did not have any net charge was 4.1. Under ambient conditions, the wetland soil had a pH of 4.2 and a slight positive net charge of +0.1meq/100g. The upland soil had a natural pH of 5.0 and a net charge of -0.25meq/100g. Both iodide and pertechnetate sorbed appreciably more to the wetland soil than to the upland soil, likely the result of more anion sorption sites derived from the organic matter in the wetland soil. In both soils, iodide sorption was greater and exhibited a greater pH-dependency than pertechnetate sorption. Pertechnetate exhibited anion exclusion (negative K
d values) or no sorption at pH values above the Point-of-Zero-Salt Effect. Iodide sorption decreased markedly as the pH increased to the zero-point-of-charge, and remained largely unchanged at pH values above the zero-point-of-charge.
Cross section measurements using gas and solid targets for production of the positron-emitting radionuclide O-14
Authors: Kovács Z. , Scholten B. , Tárkányi F. , Coenen H.H. , Qaim S.M.
Published: December 2003

Irradiation of nitrogen with protons leads to 11C (T
1/2=20.4min) via the well-known 14N(p,α) reaction. However, 14O (T
1/2=70.6s) and 13N (T
1/2=10min) are also formed as side products via the 14N(p,n) and 14N(p,d+pn) reactions, respectively. In this work detailed cross section measurements were carried out for those two side reactions up to 19.2MeV using N2 gas and nitrogen-containing solid targets. From the data, the thick-target yields and the exact level of radioactive impurities in 11C were calculated. In the case of 14O, the results also confirmed the possibility of producing this β
+ emitting radionuclide in sufficient quantities for PET investigations.
Redox speciation method for neptunium in a wide range of concentrations
Authors: Kirishima A. , Tochiyama O. , Tanaka K. , Niibori Y. , Mitsugashira T.
Published: December 2003

The adsorption method for determination of the distribution of neptunium among its oxidation states by the use of solvent impregnated resins and bismuth phosphate precipitates as adsorbents is described. For neptunium in concentration ranging from ∼10-10to ∼10-2.5M, Np(IV) and Np(VI) were quantitatively adsorbed on the impregnated resin in a solution of the acidity 1.0-0.1M HClO4, while Np(V) remained in the liquid phase. In the same condition, the precipitate of bismuth phosphate absorbed Np(IV) selectively, leaving Np(V) and Np(VI) in the liquid phase. By carrying out these adsorption methods in Ultrafree-MC Microporous Centrifugal Filter Units (Millipore Corporation), the oxidation state distribution of neptunium in acid solution can be determined in a simple manner with a small sample volume (500μl) regardless of its concentration.
Complete removal of uranyl nitrate from tissue matrix using supercritical fluid extraction
Authors: Kumar R. , Sivaraman N. , Senthil Vadivu E. , Srinivasan T. G. , Vasudeva Rao P. R.
Published: December 2003

The removal of uranyl nitrate from tissue matrix has been studied with supercritical carbon dioxide modified with methanol alone as well as complexing reagents dissolved in methanol. A systematic study of various complexing agents led to the development of an extraction procedure for the quantitative recovery of uranium from tissue matrix with supercritical carbon dioxide modified with methanol containing small quantities of acetylacetone. The drying time and temperature employed in loading of uranyl nitrate onto tissue paper were found to influence the extraction efficiency significantly.
Solubility of thorium from Th3UO8 and ZrTh3UO10 ceramics
Authors: Curran G. , Rattray W. , Czerwinski K.R.
Published: December 2003

The solubility of thorium from Th3UO8 and ZrTh3UO10 ceramics was studied to evaluate the solubility constants for the materials. Zirconium was added in order to investigate potential additional stabilization of the thorium matrix from ZrO2. Studies were performed from pH 4 to pH 9 under both 100 Argon and 10 CO2/90 Ar at 25°C in 0.1M NaClO4. Reaction kinetics and equilibrium concentrations were evaluated for each condition. Rate constants increased with pH and varied from 6×10-4 hr-1 to 4×10-2 hr-1. The surface area normalized dissolution rate decreased with increasing pH, the highest being 5×10-7gm-2 d-1 at pH 4. The solubility product constants calculated from the equilibrium concentrations for the two ceramics were equivalent, with K
{spTh₃UO₈}= -48.30.4 and K
{spZrTh₃UO₈= -47.90.9. The data was used to calculate the Th solution phase concentration. The result was compared to the dissolution of UO2 from pH 5-9 in 0.1M NaClO4 under a 1 CO2 atmosphere at 25°C. It was found that the U from the UO2 had a higher solution phase concentration than Th at high pH and was highly dependent upon the solution E
h of the evaluated conditions.
Multitracer studies on the permeation of rare earth elements through a supported liquid membrane containing 2-ethylhexyl phosphonic acid-2-ethylhexyl ester (EHEHPA)
Authors: Ambe Shizuko , Abe Daisuke , Ozaki Takuo , Ambe Fumitoshi
Published: December 2003

The simultaneous permeation of Sc, Y, Ce, Pm, Eu, Gd, Yb and Lu through a 2-ethylhexyl phosphonic acid-2-ethylhexyl ester (EHEHPA)-decalin membrane supported on a microporous polytetrafluoroethylene sheet was studied using a multitracer. The permeation rates of the elements from feed solutions of various acidity into receiving solutions of 2mol dm-3 HCl were determined. The feed solution at pH 1.5 gave the highest percentage of permeation for Ce, Pm, Eu, Gd and Yb, amounting to about 90 after -25h permeation. The percentage of permeation of Y and Lu was the highest at pH 1, amounting to about 90 after -25h permeation. The permeation of Sc from all the feed solutions was less than 4 due to its adsorption on the vessel. The permeation from the feed solution at pH 1.5 into the receiving solutions of 1, 2, 3, 4 and 5mol dm-3 HCl showed that the maximum percentage of transport for Y and Yb was obtained in 2mol dm-3 HCl receiving solution and that for Lu in 2-4mol dm-3 HCl receiving solutions. The other elements gave a percentage of transport more than 90 in 1-5mol dm-3 HCl receiving solutions, showing no obvious HCl concentration effect. The permeability coefficients of these elements were determined. Solvent extraction of the elements by EHEHPA-decalin was also carried out for comparison.
Adsorption of barium on kaolinite, illite and montmorillonite at various ionic strengths
Authors: Atun G. , Bascetin E.
Published: December 2003

The sorption behaviour of Ba2+in three different clay minerals from various regions of Turkey has been investigated by means of a tracer technique using133Ba in batch experiments. Sorption of Ba2+on montmorillonite, kaolinite and illite has been studied in mixed solutions of BaCl2and NaCl at ionic strengths ranging from 1×10-3M to 1×10-1M. The L-shape exchange isotherms for Ba2+-Na+systems are well defined by a Langmuir type equation. The exchange capacity of Ba2+ions for all three clay minerals increased with decreasing ionic strength. The adsorption data were fitted to a Freundlich isotherm and empirical Freundlich parameters enabled to the generation of a site distribution function. The selectivity coefficients were nearly constant at low Ba loading and decreased as loading increased. This behavior was an indication of an ion exchange process between Ba2+and Na+ions.
Complexation of Ni(II) by α-isosaccharinic acid and gluconic acid from pH 7 to pH 13
Authors: Warwick Peter , Evans Nick , Hall Tony , Vines Sarah
Published: December 2003

Nickel reactions with gluconic acid (Gl) andα-isosaccharinic acid (ISA) have been investigated from pH 7 to pH 13.3. Measurement of the stoichiometries of the products of these reactions showed that NiGl and NiISA were formed at pH<7, Ni2Gl(OH)3and Ni2ISA(OH)3were formed at pH values between 7 and 10 and Ni2Gl(OH)4and Ni2ISA(OH)4were formed at pH>10. The stability constants for the formation of the soluble complexes were measured using an ion exchange resin method (Schubert method) at pH 7 and 13.3, and differential pulse polarography at pH 7. The polarographic measurements were performed in order to check the validity of the Schubert method at pH 7. This was due to the possibility of any cationic complexes that may have been formed sorbing to the resin. The importance of determining the stoichiometry of the reactions before calculating the stability constants from measurements taken using the Schubert method is emphasised.
The influence of ozone on ligand-assisted extraction of239Pu and241Am from Rocky Flats soil
Authors: Plaue J. W. , Czerwinski K.R.
Published: December 2003

Chemical extraction of239Pu and241Am from a Rocky Flats soil matrix was studied at 50°C using four ligands; citric acid and ascorbic acid at pH 2, EDTA and carbonate at pH 10. The soil was treated for a -12hour reaction period with ozone gas prior to the addition of ligands. With the carbonate ligand, the ozone treatment continued during the entire extraction. High Pu removal was found at pH 2 with ascorbic acid and pH 10 with carbonate. Both maintained redox conditions during the extraction. For the carbonate system, a trend of increased extraction with increasingEhand carbonate concentration was observed. Ozone treatment of soil prior to addition of EDTA at pH 10 and citric acid at pH 2 was shown to dramatically increase extraction of Am. Since no oxidation of Am occurred, the increased removal from ozone is mainly due to the oxidation of the soil phase containing the Am.
Uranium speciation in plants
Authors: Günther A. , Bernhard G. , Geipel G. , Reich T. , Roßberg A. , Nitsche H.
Published: December 2003

Detailed knowledge of the nature of uranium complexes formed after the uptake by plants is an essential prerequisite to describe the migration behavior of uranium in the environment. This study focuses on the determination of uranium speciation after uptake of uranium by lupine plants. For the first time, time-resolved laser-induced fluorescence spectroscopy and X-ray absorption spectroscopy were used to determine the chemical speciation of uranium in plants. Differences were detected between the uranium speciation in the initial solution (hydroponic solution and pore water of soil) and inside the lupine plants. The oxidation state of uranium did not change and remained hexavalent after it was taken up by the lupine plants. The chemical speciation of uranium was identical in the roots, shoot axis, and leaves and was independent of the uranium speciation in the uptake solution. The results indicate that the uranium is predominantly bound as uranyl(VI) phosphate to the phosphoryl groups. Dandelions and lamb´s lettuce showed uranium speciation identical to lupine plants.
A fluorescence spectroscopic study on the speciation of Cm(III) and Eu(III) in the presence of organic chelates in highly basic solutions
Authors: Wang Zheming , Felmy Andrew R. , Xia Yuanxian , Mason M. J.
Published: December 2003

The speciation of Eu(III) and Cm(III) was investigated by time resolved laser fluorescence spectroscopy (TRLFS) over a range of base concentrations from 0.01M NaOH to 7.5M NaOH and in the presence of several organic chelates including EDTA, HEDTA, NTA, and oxalate. The results of this work suggest that both Eu(III) and Cm(III) form strong mixed ligand complexes with organic chelates and the hydroxyl groups(s) in dilute NaOH solutions. However, in concentrated NaOH solutions, Eu(III)-/Cm(III)-containing colloidal nanoparticles are the primary cause for the measured Eu(III)/Cm(III) in the aqueous solutions. Therefore, the interpretation of these data solely in terms of the formation of amphoteric hydroxyl species (e.g. Eu(OH)4-) would appear to be inappropriate. The organic chelating ligands form strong complexes with surface Cm(III)/Eu(III) sites of the colloidal nanoparticles. For Cm(III), such surface complexes show largely red-shifted fluorescence spectra as compared with the aqueous complexes and unusually short fluorescence lifetimes. The decreased fluorescence lifetimes are likely due to the presence of transition metal impurities in the nanoparticle and reduced inter-nuclear distance between neighboring Cm(III) centers.
Synthesis and characterization of neptunyl(VI) and plutonyl(VI) orthosilicates
Authors: Bessonov A.A. , Grigoriev M.S. , Ioussov A. B. , Budantseva N.A. , Fedosseev A.M.
Published: December 2003

(NpO2)2SiO4·2H2O (I) and (PuO2)2SiO4·2H2O (II) have been prepared by hydrothermal synthesis technique. Chemical composition of (I) was attributed to the compound from its isostructurality with (UO2)2SiO4·2H2O; crystal unit cell parameters of (NpO2)2SiO4·2H2O have been refined as orthorhombic, a=8.365(5)Å, b=11.089(5)Å, c=18.640(9)Å with the space group Fddd. (PuO2)2SiO4·2H2O has not been found isostructural with uranyl(VI) and neptunyl(VI) analogues. Chemical composition of (II) was determined by chemical analysis and proved by the formula volume calculated from powder X-ray data. Indexing of X-ray powder pattern of the prepared compound gave the tetragonal unit cell with a=6.912(3), c=18.563(3)Å, possible space group I41/amd. Visible-near IR and IR absorption spectra of the prepared compounds have been measured in NaCl and KBr. f–f absorption band of PuO2
2+ in the visible spectrum of crystal (PuO2)2SiO4·2H2O is not splitted but its maximum is essentially shifted (up to 858nm) to the long wave region in comparison with hydrated PuO2
2+ ions. Visible-near IR absorption spectrum of crystal (NpO2)2SiO4·2H2O is close to that of aqueous neptunyl(VI) solution. Thermal behavior of synthesized compounds has been studied up to 800°C in air.
A comparision of the extraction of carrier-free176,177W and99Mo with that of U, Th, Am, Cm, La, Ce, Tm, Yb, Lu and Hf into Aliquat 336 in toluene from nitric, phosphoric, and sulphuric acid media
Authors: Johansson M , Alstad J. , Omtvedt J. P. , Skarnemark G.
Published: December 2003

Carrier-free176,177W and99Mo have been extracted from 0.1-5.0M nitric, phosphoric and sulphuric acids into 0.22M Aliquat 336, CH3NR3Cl, in toluene. Their extraction properties have been compared to hafnium, to the lanthanides lanthanum, cerium, thulium, ytterbium and lutetium, and to the actinides americium, curium, thorium and uranium. From nitric acid solutions the extracted species of tungsten and molybdenum at low concentrations are probably CH3NR3· HMO4, where M=Mo or W. At higher nitric acid concentrations the extracted species are most likely similar to those of uranium,i.e. (CH3NR3)2·MO2(NO3)4and possibly CH3NR3·MO2(NO3)3. For the extraction from phosphoric acid solutions the major extracted complex is most likely CH3NR3·MO2(H2PO4)3, while the minor extracted complex may be (CH3NR3)2·MO2(H2PO4)4or even the more hydrolysed species CH3NR3·HMO4. From sulphuric acid solutions the extraction of molybdenum and tungsten has similarity with the extraction of uranium and thorium, although the decrease with acid concentration is slower.
Field study of the migration of90Sr in a weak loess aquifer
Authors: Liu C. L. , Li S. S. , Wang Z. M. , Yang Y. E. , Li B. , Jiang H. , Jiang L , Wang L. , Yao L. G. , Guo Z. M. , Li D. , Du Z. D.
Published: December 2003

The migration of90Sr in a weak loess aquifer was investigated in-situ in an Underground Research Facility. Quartz containing90Sr,3H and other nuclides was introduced into the aquifer with a stainless steel pipe. The local water flow field in the aquifer was monitored using a 3-dimensional sampling system. The contaminated area of the aquifer was marked out wholly with the help of a pre-installed stainless steel frame and cut into small pieces (samples) 3-dimensionally, and analyzed. The result of the -3year experiment indicated that90Sr had normal concentration distributions inYandZdirections. The migration rate of the mass center for90Sr inXdirection was calculated as 3.5×10-5cm/d, the distribution coefficient for90Sr in the aquifer was calculated as 7.4×102ml/g and the diffusion coefficient for90Sr in the aquifer inXdirection was calculated as 1.3×10-11m2/s.
Standardisation of the prompt gamma activation analysis method
Authors: Révay Zs. , Molnár G. L.
Published: December 2003

A complete series of measurements was performed at the Budapest prompt gamma neutron activation analysis (PGAA) facility in order to determine the partial production cross sections of the most suitable neutron capture gamma rays for all naturally occurring elements, excluding noble gases. The values were determined directly, with internal standardisation using stoichiometric compounds and homogeneous mixtures (mainly water solutions) of known composition. A comparison with a recent measurement for 20 elements shows good agreement except for a few non-1/v cross sections. The new data are sufficiently accurate for quantitative multielement determinations in PGAA without the necessity of elemental standards.
Pu-Th separation studies employing di(2-ethylhexyl)isobutyramide (D2EHIBA) as extractant from nitric acid medium
Authors: Pathak P.N. , Prabhu D. R. , Rizvi G. H. , Ruikar P.B. , Kumbhare L.B. , Mohapatra P.K. , Manchanda V.K.
Published: December 2003

An attempt has been made to explore the use of di(2-ethylhexyl)isobutyramide (D2EHIBA) as an extractant for the recovery of Pu from the (proposed) AHWR fuel fabrication scrap solution. The extraction of Pu in the hexavalent state has been found to be distinctly more efficient than that in the tetravalent state. Distribution studies have been carried out by maintaining Pu as Pu(VI) employing AgO as the oxidant. Scrubbing at 5M HNO3 has been proposed to reduce the interference due to the co-extracted Th(IV). Quantitative stripping of the extracted Pu was achieved using Hydroxyl Ammonium-Nitrate (HAN) as reductant. Ion exchange studies have been carried out for the final purification of Pu. It is proposed to employ the cation exchanger, Biorad AG 50X8 for the final purification of Pu from the stripped solution, keeping Pu as Pu(III).
New laser induced photoacoustic signal measurement method. Example of application: Identification of the uranium(IV)-dioxalato complex in solution
Authors: Mesmin Claire , Roudil Danièle , Hanssens Alain , Madic Charles
Published: December 2003

A new laser induced photoacoustic signal measurement method was developed to optimise the parameters of photoacoustic detection: to obtain synchronous measurement, to avoid laser energy fluctuation, to get reproductibility and repeatability. The aim is to apply the technique to solution chemistry, and particularly to studies of the actinides. The initial validation of the new method was done using neodymium(III) and uranium(IV) solutions in acidic media. It was found that the sensitivity of detection of these ions by photoacoustic measurements is improved in comparison with absorption spectrophotometry. This advantage in radiochemistry is the possibility to study actinides at low concentration (<10-4M) to understand their behaviour in solution: speciation, precipitation, kinetics. An example is described and concerns the identification of the uranium(IV)-dioxalato complex in solution by proposing a new mechanism for the precipitation of U(C2O4)2·6H2O.In this work, a measurement device is proposed for rough pressure wave acquisition. It allows sensor definition, local phenomena observation and alternative LIPAS measurement.
Comparative study on the evaluation of gamma-dose rate above uranium mineralisation areas in Western Sudan
Authors: Sam A. K. , Sirelkhatim D. A.
Published: December 2003

Absorbed dose rate received from natural external irradiation in uranium mineralisation areas at Jebel Uro, Jebel Kurun and Jebel Mun was evaluated from the measured activity concentrations of 238U, 232Th and 40K in rock samples. The analyses were performed using alpha-spectrometry and high-resolution gamma-ray spectrometry. A great spatial variability was observed in activity concentration of the primordial radionuclides indicating complexity in geological features. Converse to Jebel Mun, Uro and Kurun deposits exhibit very high U: Th mass ratio, the feature that characterized vein deposits. The resulting absorbed dose rate at 1m above bedrock level as estimated using dose rate conversion factors (DRCF) fall within the range of 70-500nGy/h (Mun), 600-6000nGy/h (Uro) and 80-300nGy/h (Kurun). At maximum, it corresponds to annual effective dose rate of 0.6mSv, 8mSv and 0.4mSv, respectively. Uranium is the principal producer of the surface radioactivity at Uro and Kurun as it contributes 99.6 and 95 of the total absorbed dose whereas, in Jebel Mun the cause of radioactive anomaly is due to 40K and 232Th. Regression analysis showed no correlation between uranium concentration and other radionuclides. Although, radioactive equilibrium is not likely to occur in surface and near-surface geological environments, however, daughter/parent activity concentration ratios along uranium series, viz. 234U:238U, Ra:U, 230Th:U, 210Po:U do not differ from unity in both Uro and Kurun deposits.
Efficacy of a new tan doped sol-gel sorbent for uptake of zinc
Authors: Khan Aslam , Ahmed Shujaat , Mahmood Farzana , Khokhar M. Younas , Riaz M.
Published: December 2003

A TAN (1-(2-Thiazolylazo)-2-naphthol)) doped sol gel silica sorbent (reddish colour, porous, stable, hard, non- swelling) were prepared and investigated for the removal of Zn (II) from aqueous solutions. The kinetics, adsorption isotherm, equilibration time and pH effect on the removal were studied from non competitive aqueous solution to optimize the conditions to be utilized on a large scale. Fast equilibration was observed and adsorption equilibria were reached within 30minutes. Adsorption of zinc ions on the blank (un-doped) sol gel was found negligible. The maximum adsorption of Zn (II) ions onto the TAN doped sol-gel from single solutions were 2.33mg/g (0.035mmol/g). TAN doped sol gel can be regenerated through washing with a solution of 0.1M HCl solution. The maximum regeneration value was as high as 99.0. The TAN-doped sol gel silica is suitable at least for four adsorption-desorption cycles without experiencing considerable loss of adsorption capacity. The uptake route and the nature of the Zn-TAN complex have been discussed.
Electrochemical dissolution of simulated "white inclusions" in nitric acid. Linear voltammetry study with Mo, Re, Ru metals and their alloys electrodes
Authors: Maslennikov A. , Fourest B. , David F. , Masson M.
Published: December 2003

The process of electrochemical dissolution of pure Mo, Re and Ru metals, as well as their alloys 52.5 at. Mo – 47.5 at. Re and 90 at. Mo – 10 at. Ru in 0.5-6.0M HNO3 was studied using the linear voltammetry technique. The dissolution potentials of the pure metals were found to increase from 0.39 to 0.48V/SCE (Mo), from 0.7 to 0.81V/SCE (Re) and from 1.15 to 1.25V/SCE (Ru) with the augmentation of HNO3 concentration in the electrolyte. The dissolution potentials of the alloys 52.5 at. Mo + 47.5 at. Re and 90 at. Mo + 10 at. Ru were found to change from 0.49 to 0.58 (Mo-Re) and from 0.92 to 1.09 (Mo-Ru) when HNO3 concentration in the electrolyte increased from 0.5 to 6.0M. The secondary passivation of Mo-containing electrodes was observed in the solutions 2.0-6.0M HNO3 at the potentials from 1.4 to 1.9V/SCE, decreasing their dissolution rate in this range of potentials. The maximum electrochemical dissolution rate constants of pure Mo, Re, Ru metals and Mo-Re, Mo-Ru alloys have been estimated using the data of linear voltammetry. The obtained values (1.85-2.20g/cm2 h for Mo-Re and 0.58-0.64g/cm2 h for Mo-Ru alloys electrochemical dissolution) are found to be thousand times greater, than reported for the process of chemical dissolution of corresponding alloys in boiling HNO3.
Chemical identification and properties of element 112
Authors: Yakushev Alexander B. , Zvara I. , Oganessian Yu. Ts. , Belozerov A. V. , Dmitriev S. N. , Eichler B. , Hübener S. , Sokol E. A. , Türler A. , Yeremin A. V. , Buklanov G. V. , Chelnokov M. L. , Chepigin V. I. , Gorshkov V. A. , Gulyaev A. V. , Lebedev V. Ya. , Malyshev O. N. , Popeko A. G. , Soverna S. , Szeglowski Z. , Timokhin S. N. , Tretyakova S. P. , Vasko V. M. , Itkis M. G.
Published: December 2003

We present results of the second experiment on the chemical identification of element 112. Similar to the first test in 2000, we aimed at the production of the spontaneously fissioning 283112 nuclei with T
1/2≈3min. A natU3O8 (with some Nd) target, 2mg of U/cm2 thick, was bombarded with 233-MeV 48Ca ions (the energy in the middle of the target layer). The nuclei recoiling from the target were thermalized in flowing helium. The target chamber was connected through a 25m long capillary to detectors of α-particles and fission fragments. All the equipment and detectors were kept at ambient temperature. According to the test experiments, of all the heavy elements produced in the bombardment, only Hg, Rn and At could be transported to the detectors. The first detecting device was similar to that used earlier – an assembly of 8 pairs of PIPS detectors coated with gold. Here one would observe the decay of element 112 atoms if they like Hg adsorbed on gold. The atoms which were not retained and freely passed through the PIPS detectors entered a new, flow-through ionization chamber, 5000 cm3 in volume, optimized for detecting fission fragments. The PIPS detectors and the ionization chamber were placed inside a large assembly of 3He – filled neutron counters to detect prompt neutrons from the fission events. In 22.5 days, a beam dose of 2.8×1018 ions was accumulated. More than 95 of the simultaneously produced α-active 185Hg (T
1/2=49 s) were found deposited already on the first pair of PIPS detectors; meanwhile, all the PIPSs did not detect any fission event. In the ionization chamber, eight fission events were observed in coincidence with neutron counts while the expected background was insignificant. Hence, the spontaneous fissions of the volatile activity can be conclusively attributed to the decay of element 112 produced in the fusion reaction 48Ca+ 238U, and formerly observed in Dubna physical experiments. Evaluation of the experimental data in terms of the adsorption enthalpies indicates much weaker interaction of element 112 with Au than that of Hg. One can conclude that in the given chemical environment, element 112 behaves like Rn rather than like Hg. The formation cross section of 283112 estimated from the data amounts to several pb. The experiments were carried out at the Flerov Laboratory of Nuclear Reactions at JINR in November–December 2001.
Temperature dependence and effect of oxide anion on the americium chemistry in the molten LiCl-KCl eutectic
Authors: Lambertin David , Sanchez Sylvie , Picard Gérard S. , Lacquement Jérôme
Published: December 2003

The chemical properties of americium chlorides have been studied in the fused eutectic LiCl-KCl as a function of temperature ranging from 743K to 943K. Titration of Am(III) chlorocomplex by O2- demonstrated the existence of soluble AmO+ species as well as the precipitation of AmOCl and Am2O3 solid compounds. The corresponding solubility products of AmOCl and Am2O3 have been determined. Calculated Am(II) disproportionation equilibrium constant indicates that the stability of Am(II) chlorocomplex increases with the increase of temperature.
Limiting transport properties of lanthanide and actinide ions in pure water
Authors: Mauerhofer E. , Zhernosekov K. P. , Rösch Frank
Published: December 2003

The limiting transport properties,i.e. the limiting ionic conductivity (λ°) and the limiting diffusion coefficient (D°), of lanthanide and actinide ions at 298.15K have been calculated by means of the microscopic version of the Stokes–Einstein law involving (i) the effective charge and the ionic radius of the ions and (ii) the ion micro-viscosity,i.e. the viscosity of the hydrated water molecules in the vicinity of the ion. The latter quantity was derived from the variation of the dynamic properties of the water molecules in the first hydration shell with the surface charge density of common mono-atomic cations of various charges. The obtained results were found to be consistent with the experimental data given in the literature.
Application of microanalytical techniques to the study of aqueous ion sorption phenomena on mineral surfaces
Authors: Badillo-Almaraz V. E. , Toulhoat N. , Trocellier P. , Jullien M.
Published: December 2003

Nuclear microprobe analysis has been used to study the aqueous sorption of cadmium and selenium at different solution pH values onto hydroxyapatite. By coupling Particle Induced X-ray Emission (PIXE) and Rutherford Backscattering (RBS) microanalyses, we have quantified the concentration and modeled the depth distribution of Cd and Se in particles of calcium hydroxyapatites (HAP). No cadmium precipitation was observed for those experiments in which the initial concentration was greater than the solubility of Cd(OH)2and CdCO3at solution pH=9 and 12. The observation of the solid by transmission and scanning electron microscopies, SEM and TEM, showed the polycrystalline nature of the particles; these particles were constituted by aggregated nanocrystals. This additional information allowed us to interpret the incorporation of Cd and Se into the apatitic substrate as a penetration in the intra-particle porosity generated by this aggregation of crystals and probably not as diffusion in the solid structure.
Preparation of a stable tracer solution of plutonium(IV)
Authors: Bajo Sixto , Eikenberg J.
Published: December 2003

A method is given for the preparation of a Pu tracer solution in 0.10M NaHSO4 containing only Pu(IV). This solution is stable for several years.
Heterogeneous catalytic oxidation of neptunium(IV) in nitric acid solutions
Authors: Ananiev A. V. , Shilov V.P. , Moisy Ph. , Madic Charles
Published: December 2003

Neptunium(IV), being quite stable in 0.5–3M HNO3, undergoes quick oxidation in the presence of 1 Pt/SiO2 catalyst. It was found that the catalytic oxidation of neptunium(IV) in nitric acid solutions proceeds even in the presence of anti-nitrous agent (such as NH2SO3H), though the rate of the reaction decreases to some extent. The kinetics of the heterogeneous catalytic oxidation of neptunium(IV) in nitric acid were studied for the following conditions: [HNO3] = 0.5–4.0M; [NH2SO3H] = 0 and 0.1M; T = 4070°C; S/L = 0.025–0.1g/mL 1 Pt/SiO2. It was proposed that the mechanism of the neptunium(IV) oxidation is a result of the heterogeneous interaction of the Np(IV) aqua-ion with the nitronium ion NO2
+ on the surface of the catalyst. The reaction deceleration and the increase of the apparent activation energy with the increase of the nitric acid concentration is explained by the complex formation of neptunium(IV) with nitrate ion.
Complexation of U(VI) with iodate ions: determination of stability constants by using spectroscopic methods and capillary zone electrophoresis
Authors: Karbowiak M. , Fourest B. , Hubert S. , Moulin Christophe
Published: December 2003

The uranyl iodate system has been studied by using three speciation methods: laser-induced time-resolved fluorescence spectroscopy (TRLIFS), UV-visible spectrophotometry and capillary zone electrophoresis with direct UV detection (CZE). Two uranyl iodate complexes were found: UO2IO3-and UO2(IO3)2in 0.05M NaClO4solutions of pH 2.6, depending on the iodate concentration. The three methods are convenient and efficient for determining the complex formation constants of the two complexes. The variation of the uranyl mobility as a function of the ligand concentration is very simple to analyse and its fitting leads to accurate thermodynamic data. The values obtained for logβ11(1.6±0.1) and logβ12(3.05±0.1) are in good agreement with the previously published values. Both complexes were also characterized by their fluorescence spectra and fluorescence lifetime. From the analysis of the fluorescence spectra, taking into account the dynamic quenching, the complex formation constants were calculated, in reasonable agreement with the ones obtained by capillary electrophoresis: logβ11(1.5±0.2) and logβ12(3.6±0.2).
Investigation of sorption of Hg(II) ions onto coconut husk from aqueous solution using radiotracer technique
Authors: Hasany Syed Moosa , Ahmed Rashid , Chaudhary Munawar Hussain
Published: December 2003

The sorption of Hg(II) ions onto coconut (Cocos nucifera) husk has been studied using radiotracer technique. Maximum sorption (96) of Hg(II) ions (7.39×10-6M) onto sorbent surface is achieved from 10-3M HNO3 solution in 30min agitation time using 100mg of coconut husk. The sorption data follow the Freundlich and Dubinin–Radushkevich (D–R) isotherms. Sorption capacity (6.84 ± 0.45 mmol g-1) and sorption energy (10.6 ± 0.13 kJ mol-1) have been evaluated using these isotherms. Among the ions tested to monitor their influence on the sorption, Ba(II), fluoride and tartarate increased the sorption, while thiosulfate, bromide and thiocyanate reduced (< 63 > 26) the sorption. The cations K(I), Ce(III), Cr(III), Fe(III) and Zr(IV) partially suppressed the sorption. The variation of sorption with temperature yields thermodynamic parameters ΔH = -37.42 kJ mol-1 ΔS = -1057J mol-1K-1 and ΔG = -2.58 ± 0.05 kJ mol-1 at 298 K. The negative values of enthalpy and free energy reflect the spontaneous and exothermic nature of sorption, respectively. The selectivity studies of sorbent show that the coconut husk column can be used to separate Hg(II) ions from Se(IV), Zn(II), I(I) and Tc (VII). The sorbent has a potential in radiochemistry to separate gamma energies of 203Hg (279 keV) from 75Se (265 and 280 keV).
Evaluation of novel getters for adsorption of radioiodine from groundwater and waste glass leachates
Authors: Mattigod S. V. , Fryxell G. E. , Serne R. J. , Parker K. E.
Published: December 2003

Performance tests were conducted using novel getter materials that can immobilize or delay the transport of radioiodine that would be released during physical and chemical degradation of solidified low-level waste packages. The results showed that metal-capped novel getters such as Hg-thiol and Ag-thiol Self-Assembled Monolayers on Mesoporous Silica (SAMMS), designed specifically to adsorb soft anions such as I-, had very high affinities for adsorption of radioiodine (K
d ∼ 1×104 – 4×105 ml/g). The iodide adsorption performance of these novel getters was from one to two orders of magnitude better than many natural mineral and modified mineral getters. These data indicate that the novel getter materials are capable of significantly retarding the mobility of radioiodine leaching from physically and chemically weathered low-level waste glass packages during various physical and chemical weathering reactions expected during long-term disposal in the vadose zone.
Radiochemical neutron activation analysis for trace elements evaluation of human milk
Authors: Gill K. P. , Zaidi Jamshed H. , Ahmad S.
Published: December 2003

The principal objective pursued in this study is to establish the base-line data on the status of elemental composition in human milk from Pakistani subjects of Rawalpindi/Islamabad area. Radiochemical neutron activation analysis (RNAA) methodology was developed and successfully employed to determine the concentration of 18 minor and trace elements (essential, toxic and nonessential) in human milk. This methodology has significantly improved the detection limits of most of these elements due to suppression of Compton background. The data provide the base-line values of these elements in human milk of low- and medium-income group subjects of the region. The results obtained show good compatibility with the data reported by the WHO on elemental composition of human milk from different geological regions.
Absolut messendes Diodenlaserinterferometer (Diode Laser Interferometer for Absolute Distance Measurement)
Authors: Burgarth V. , Zhang C. , Abou-Zeid A.
Published: December 2003

Absolut messende Interferometer werden für die Bestimmung größerer Längen bei praktischen Anwendungen selten genutzt. Die Vorteile überwiegen die Kosten bei vielen Anwendungen nicht. Es wird ein absolut messendes Interferometer vorgestellt, das geringere Anforderungen an Laser, Längenreferenz und Umgebungsbedingungen stellt. Das Messprinzip, die Komponenten und Untersuchungen zur Messunsicherheit des Interferometers werden beschrieben.
Simultane Erfassung von 3D-Form und Farbe komplexer Objekte (Simultaneous Measurement of Shape and Color of Complex Objects)
Authors: Notni G. H. , Kühmstedt P. , Heinze M. , Notni G.
Published: December 2003

Methoden zum Erfassen der 3D-Form von Objekten sind seit vielen Jahren bekannt. In verschiedenen Anwendungen ist es jedoch notwendig, die Objektform und -farbe komplex geformter Objekte vollständig zu erfassen. Die Verwendung von Farbkameras hat den Nachteil niedriger Auflösung, niedriger Bildraten und kann Formmessfehler verursachen. Die hier vorgestellte Messmethode ermöglicht die simultane Erfassung von Form und Farbe unter ausschließlicher Verwendung von Monochromkameras.
Neue Konzepte für ein faserbasiertes Messsystem zur absoluten Abstandsmessung (New Concepts for a Fiber Based System for Absolute Distance Measurements)
Authors: Bosbach C. , Pfeifer T. , Depiereux F.
Published: December 2003

Der Einsatz und die Nutzung von miniaturisierten Bauteilen oder Produkten ist seit Jahren etabliert, sei es in der Telekommunikation oder Automobilbranche. Jedoch ist die Frage nach geeigneten Produktionsverfahren und -mitteln immer aktuell und ist in vielen Fällen noch nicht ausreichend gelöst bzw. es stehen noch Lösungen aus. Gerade Bereiche der Prozesskontrolle bzw. -regelung mittels Messtechnik bergen Entwicklungspotentiale. Der vorliegende Artikel zeigt die Entwicklung eines faserbasierten Abstandsmesssystems und dessen Einsatzmöglichkeiten.
Erzeugung und Auswertung von objektangepassten inversen Projektionsmustern (Generation and Evaluation of Object Adapted Inverse Patterns for Projection)
Authors: Bothe T. , Li W. , Kopylow C. von , Jüptner W.
Published: December 2003

Die inverse Streifen- und Muster-Projektionstechnik wird vorgestellt und mit Anwendungsbeispielen verknüpft. Die Technik erlaubt eine schnelle und robuste 3D-Qualitätskontrolle sowie eine schnelle Formprüfung, da nur ein Kamerabild zur Auswertung jeweils eines Zustandes benötigt wird. Beliebige Muster können unabhängig von der Objekthöhenstruktur an das Objekt angepasst werden. Beliebige (gemessene) Bilddaten können für den Experimentator direkt auf dem Objekt an den korrespondierenden Positionen markiert werden (Augmented Reality).
Messung der Funkstörfeldstärke mit GTEM-Zellen (Measurements of Disturbance Field Strength using GTEM Cells)
Authors: Karsten U.
Published: December 2003

GTEM-Zellen sind seit über 10 Jahren weltweit im Einsatz. Voraussetzung für die Anwendung von Wellenleitern für Emissionsmessungen ist ein spezieller Algorithmus zur Umrechnung der Messergebnisse. Durch zahlreiche Messungen unterschiedlicher Prüflinge wurde die Vergleichbarkeit dieser Ergebnisse mit Messungen auf Freifeldern nachgewiesen. Die Anordnung der Anschlussleitungen hat einen großen Einfluss auf das Ergebnis.
Emissionsmessung in Modenverwirbelungskammern (Radiated Emission Measurement in Mode-tuned Reverberation Chambers)
Authors: Kürner W.
Published: December 2003

In diesem Beitrag wird die Verwendung von Modenverwirbelungskammern (MVK) für gestrahlte Emissionsmessungen beschrieben. Die Grundlage für solche Messungen bildet die Norm IEC 61000-4-21, die bisher als CVD vorliegt. Ebenfalls werden Vergleiche zu Messergebnissen in Absorberkammern gezogen und die Vor- und Nachteile von MVK diskutiert.
Untersuchung eines hybriden EMV-Simulationsverfahrens anhand eines virtuellen Komponententests (Detailed Analysis of a Hybrid EMC-Simulation Tool)
Authors: Rinkleff T. , Hillgärtner M.
Published: December 2003

Bei der zunehmenden Komplexität und Elektrifizierung von Fahrzeugen wird es immer wichtiger, im frühen Entwicklungsstadium elektromagnetische Problemstellen aufzudecken und zu beseitigen. In diesem Zusammenhang können hybride Simulationsverfahren einen wichtigen Beitrag liefern. In diesem Artikel wird ein Vergleich von Messung und hybrider Simulation am Beispiel einer Störfestigkeitsuntersuchung einer Bordnetzkomponente gezogen.
Emissionsmessungen mit Antennen (Antenna-based Emission Measurements)
Authors: Mönich G.
Published: December 2003

Die Betrachtung von Antennen zur Messung von Störstrahlung erfordert ein Grundverständnis für die beim Empfang ablaufenden Vorgänge. Dieses wird anhand von Stabdipolen zunächst für transiente, dann für zeitharmonische Vorgänge geliefert. Der Umsetzungsfaktor von E-Feldstärke in Leerlaufspannung wird zunächst für Empfangsdipole angegeben. Um diesen für beliebige Antennen zu erhalten, wird das Reziprozitätsgesetz benötigt. Darauf aufbauend wird mittels der Referenzantenne Hertz'scher Dipol dann für die ganze Palette der in der EMV-Messtechnik gebräuchlichen Sendeantennen die Effektivhöhe der Empfangsantenne abgeleitet. Als einzige nur in der Emissionsmesstechnik einsetzbare Antennen werden die sog. Schnüffelsonden dargestellt. Der Darstellung von Hallen- und Freifeldmessplatz folgt eine kurze Diskussion der Eignungskriterien. Abschließend wird auf die Beziehung zwischen antennengestützten und alternativen Messverfahren eingegangen.