bluuebunny/crossref_metadata_2025 huggingface dataset:
Osteostat/Tumor Necrosis Factor Superfamily 18 Inhibits Osteoclastogenesis and Is Selectively Expressed by Vascular Endothelial Cells
Authors: Nardelli Bernardetta , Zaritskaya Liubov , McAuliffe William , Ni Yansong , Lincoln Clint , Cho Yun Hee , Birse Charles E. , Halpern Wendy , Ullrich Stephen , Moore Paul A.
Published: September 2005

Vascular endothelial cells (EC) participate in the process of bone formation through the production of factors regulating osteoclast differentiation and function. In this study, we report the selective expression in primary human microvascular EC of Osteostat/TNF superfamily 18, a ligand of the TNF superfamily. Osteostat protein is detectable in human microvascular EC and is highly up-regulated by IFN-α and IFN-β. Moreover, an anti-Osteostat antibody strongly binds to the vascular endothelium in human tissues, demonstrating that the protein is present in the EC layers surrounding blood vessels. Functional in vitro assays were used to define Osteostat involvement in osteoclastogenesis. Both recombinant and membrane-bound Osteostat inhibit differentiation of osteoclasts from monocytic precursor cells. Osteostat suppresses the early stage of osteoclastogenesis via inhibition of macrophage colony-stimulating factor-induced receptor activator of NF-κB (RANK) expression in the osteoclast precursor cells. This effect appears to be specific for the differentiation pathway of the osteoclast lineage, because Osteostat does not inhibit lipopolysaccharide-induced RANK expression in monocytes and dendritic cells, or activation-induced RANK expression in T cells. These findings demonstrate that Osteostat is a novel regulator of osteoclast generation and substantiate the major role played by the endothelium in bone physiology.
Posttranslational, Reversible O-Glycosylation Is Stimulated by High Glucose and Mediates Plasminogen Activator Inhibitor-1 Gene Expression and Sp1 Transcriptional Activity in Glomerular Mesangial Cells
Authors: Goldberg Howard J. , Whiteside Catharine I. , Hart Gerald W. , Fantus I. George
Published: September 2005

Metabolic flux through the hexosamine biosynthetic pathway (HBP) is increased in the presence of high glucose (HG) and potentially stimulates the expression of genes associated with the development of diabetic nephropathy. A number of synthetic processes are coupled to the HBP, including enzymatic intracellular O-glycosylation (O-GlcNAcylation), the addition of single O-linked N-acetylglucosamine monosaccharides to serine or threonine residues. Despite much data linking flow through the HBP and gene expression, the exact contribution of O-GlcNAcylation to HG-stimulated gene expression remains unclear. In glomerular mesangial cells, HG-stimulated plasminogen activator inhibitor-1 (PAI-1) gene expression requires the HBP and the transcription factor, Sp1. In this study, the specific role of O-GlcNAcylation in HG-induced PAI-1 expression was tested by limiting this modification with a dominant-negative O-linked N-acetylglucosamine transferase, by overexpression of neutral β-N-acetylglucosaminidase, and by knockdown of O-linked β-N-acetylglucosamine transferase expression by RNA interference. Decreasing O-GlcNAcylation by these means inhibited the ability of HG to increase endogenous PAI-1 mRNA and protein levels, the activity of a PAI-1 promoter-luciferase reporter gene, and Sp1 transcriptional activation. Conversely, treatment with the β-N-acetylglucosaminidase inhibitor, O-(2-acetamido-2-deoxy-d-glucopyranosylidene)amino-N-phenylcarbamate, in the presence of normal glucose increased Sp1 O-GlcNAcylation and PAI-1 mRNA and protein levels. These findings demonstrate for the first time that among the pathways served by the HBP, O-GlcNAcylation, is obligatory for HG-induced PAI-1 gene expression and Sp1 transcriptional activation in mesangial cells.
Altered Glucose and Insulin Responses to Brain Medullary Thyrotropin-Releasing Hormone (TRH)-Induced Autonomic Activation in Type 2 Diabetic Goto-Kakizaki Rats
Authors: Ao Yan , Toy Natalie , Song Moon K. , Go Vay Liang W. , Yang Hong
Published: September 2005

Insulin secretion is impaired in type 2 diabetes (T2D). The insulin and glucose responses to central autonomic activation induced by excitation of brain medullary TRH receptors were studied in T2D Goto-Kakizaki (GK) rats. Blood glucose levels in normally fed, pentobarbital-anesthetized GK and nondiabetic Wistar rats were 193 and 119 mg/100 ml in males and 214 and 131 mg/100 ml in females. Intracisternal injection (ic) of the stable TRH analog RX 77368 (10 ng) induced significantly higher insulin response in both genders of overnight-fasted GK rats compared with Wistar rats and slightly increased blood glucose in female Wistar rats but significantly decreased it from 193 to 145 mg/100 ml in female GK rats. RX 77368 (50 ng) ic induced markedly greater glucose and relatively weaker insulin responses in male GK rats than Wistar rats. Bilateral vagotomy blocked ic RX 77368-induced insulin secretion, whereas adrenalectomy abolished its hyperglycemic effect. In adrenalectomized male GK but not Wistar rats, ic RX 77368 (50 ng) dramatically increased serum insulin levels by 6.5-fold and decreased blood glucose levels from 154 to 98 mg/100 ml; these changes were prevented by vagotomy. GK rats had higher basal pancreatic insulin II mRNA levels but a lower response to ic RX 77368 (50 ng) compared with Wistar rats. These results indicate that central-vagal activation-induced insulin secretion is susceptible in T2D GK rats. However, the dominant sympathetic-adrenal response to medullary TRH plays a suppressing role on vagal-mediated insulin secretion. This unbalanced vago-sympathetic activation by medullary TRH may contribute to the impaired insulin secretion in T2D.
Utilization of Different Aquaporin Water Channels in the Mouse Cervix during Pregnancy and Parturition and in Models of Preterm and Delayed Cervical Ripening
Authors: Anderson Judy , Brown Naoko , Mahendroo Mala S. , Reese Jeff
Published: September 2005

Biochemical changes of cervical connective tissue, including progressive disorganization of the collagen network and increased water content, occur during gestation to allow for cervical dilatation during labor, but the mechanisms that regulate cervical fluid balance are not fully understood. We examined whether aquaporins (AQPs), a family of membrane channel proteins that facilitate water transport, help mediate fluid balance in the mouse cervix during parturition. Of the 13 known murine AQPs, AQP0–2, 6, 7, 9, 11, and 12 were absent or at the limits of detection. By Northern blot and real-time PCR, AQP3 expression was low in nongravid and mid-pregnancy cervices with peak expression on d 19 and postpartum d 1 (PP1). AQP4 expression was generally low throughout pregnancy but showed a small upward trend at the time of parturition. AQP5 and AQP8 expression were significantly increased on d 12–15 but fell to nongravid/baseline by d 19 and PP1. By in situ hybridization and immunohistochemistry, AQP3 was preferentially expressed in basal cell layers of the cervical epithelium, whereas AQP4, 5, and 8 were primarily expressed in apical cell layers. Females with LPS-induced preterm labor had similar trends in AQP4, 5, and 8 expression to mice with natural labor at term gestation. Mice with delayed cervical remodeling due to deletion of the steroid 5α-reductase type 1 gene showed significant reduction in the levels of AQP3, 4, and 8 on d 19 or PP1. Together, these studies suggest that AQPs 3, 4, 5, and 8 regulate distinct aspects of cervical water balance during pregnancy and parturition.
Effects of a Fixed Meal Pattern on Ghrelin Secretion: Evidence for a Learned Response Independent of Nutrient Status
Authors: Drazen Deborah L. , Vahl Torsten P. , D’Alessio David A. , Seeley Randy J. , Woods Stephen C.
Published: September 2005

Circulating levels of the orexigenic peptide ghrelin increase during fasting and decrease with refeeding. Exogenous ghrelin administration is a potent stimulus for food intake in rodents and humans. In subjects on fixed feeding schedules, ghrelin increases before each meal, raising the possibility that anticipation of meals, in addition to effects of fasting and feeding, contributes to ghrelin secretion. To distinguish among these regulatory influences, plasma ghrelin profiles were generated in freely fed rats and in meal-fed rats trained to consume their daily calories over a 4-h period in the light phase. In freely feeding rats, plasma ghrelin levels increased to a peak of 778 ± 95 pg/ml just before the onset of the dark. Similarly, in meal-fed rats anticipating a large meal of either chow or Ensure at their usual feeding time, plasma ghrelin increased steadily over the 2 h preceding the meal to peaks of 2192 ± 218 and 2075 ± 92 pg/ml, respectively. When freely fed rats were food deprived for a time equivalent to meal-fed rats, there was no peak of plasma ghrelin. In addition, eating-induced suppression of the ghrelin response differed significantly between meal-fed rats and ad libitum-fed rats receiving meals of similar size. These findings indicate that anticipation of eating, as well as fasting/feeding status, influences pre- and postprandial plasma ghrelin levels in rats. Together, these data are consistent with a role for ghrelin in the regulation of anticipatory processes involved in food intake and nutrient disposition.
Identification of the Major Oxidative 3α-Hydroxysteroid Dehydrogenase in Human Prostate That Converts 5α-Androstane-3α,17β-diol to 5α-Dihydrotestosterone: A Potential Therapeutic Target for Androgen-Dependent Disease
Authors: Bauman David R. , Steckelbroeck Stephan , Williams Michelle V. , Peehl Donna M. , Penning Trevor M.
Published: September 2005

Androgen-dependent prostate diseases initially require 5α-dihydrotestosterone (DHT) for growth. The DHT product 5α-androstane-3α,17β-diol (3α-diol), is inactive at the androgen receptor (AR), but induces prostate growth, suggesting that an oxidative 3α-hydroxysteroid dehydrogenase (HSD) exists. Candidate enzymes that posses 3α-HSD activity are type 3 3α-HSD (AKR1C2), 11-cis retinol dehydrogenase (RODH 5), L-3-hydroxyacyl coenzyme A dehydrogenase , RODH like 3α-HSD (RL-HSD), novel type of human microsomal 3α-HSD, and retinol dehydrogenase 4 (RODH 4). In mammalian transfection studies all enzymes except AKR1C2 oxidized 3α-diol back to DHT where RODH 5, RODH 4, and RL-HSD were the most efficient. AKR1C2 catalyzed the reduction of DHT to 3α-diol, suggesting that its role is to eliminate DHT. Steady-state kinetic parameters indicated that RODH 4 and RL-HSD were high-affinity, low-capacity enzymes whereas RODH 5 was a low-affinity, high-capacity enzyme. AR-dependent reporter gene assays showed that RL-HSD, RODH 5, and RODH 4 shifted the dose-response curve for 3α-diol a 100-fold, yielding EC50 values of 2.5 × 10−9m, 1.5 × 10−9m, and 1.0 × 10−9m, respectively, when compared with the empty vector (EC50 = 1.9 × 10−7m). Real-time RT-PCR indicated that L-3-hydroxyacyl coenzyme A dehydrogenase and RL-HSD were expressed more than 15-fold higher compared with the other candidate oxidative enzymes in human prostate and that RL-HSD and AR were colocalized in primary prostate stromal cells. The data show that the major oxidative 3α-HSD in normal human prostate is RL-HSD and may be a new therapeutic target for treating prostate diseases.
Increased Plasma Pro-B-Type Natriuretic Peptide in Infants of Women with Type 1 Diabetes
Authors: Halse Karen G , Lindegaard Marie LS , Goetze Jens P , Damm Peter , Mathiesen Elisabeth R , Nielsen Lars B
Published: September 2005

Background: Up to 40% of newborn infants of women with type 1 diabetes have echocardiographic signs of cardiomyopathy. Increased plasma concentrations of B-type natriuretic peptide (BNP) and its precursor (proBNP) are markers of cardiac failure and hypoxia in adults. In this study, we investigated whether plasma concentrations of proBNP and/or BNP are increased in infants of women with type 1 diabetes.

Methods: Plasma BNP and proBNP were measured with RIAs. The proBNP assay measures both intact proBNP and NH2-terminal fragments derived from this precursor, whereas the BNP assay measures only BNP-32 and not proBNP.

Results: Infants of women with diabetes and hemoglobin A1c (Hb A1c) ≥6.2% before delivery had a higher median plasma proBNP concentration (31 pmol/L; interquartile range, 21–47 pmol/L; n = 16) than infants of healthy women [16 (9–32) pmol/L; n = 21; P = 0.01]. Infants of women with diabetes and Hb A1c <6.2% (n = 15) had intermediate values. The plasma BNP and proBNP concentrations were closely associated (r2 = 0.80; P <0.0001); within the group of infants of women with diabetes and Hb A1c ≥6.2%, both correlated with the degree of fetal stress during labor.

Conclusions: Maternal diabetes and suboptimal metabolic control may affect the fetal heart and predominantly stimulate proBNP secretion in conjunction with perinatal stress.
Excitation functions of proton induced reactions on68Zn from threshold up to 71 MeV, with specific reference to the production of67Cu
Authors: Stoll T. , Kastleiner S. , Shubin Yu. N. , Coenen Heinz H. , Qaim Syed M.
Published: September 2005

The excitation function of the68Zn(p, 2p)67Cu reaction was measured radiochemically up to a proton energy of 71 MeV to obtain accurate data for production of the therapy related β−-emitting radioisotope67Cu (T1/2= 61.9 h). Investigations were also made on the (p, 2n) and (p, 3n) reactions on68Zn. The experimental cross sections of the68Zn(p, 2p)67Cu,68Zn(p, 2n)67Ga and68Zn(p, 3n)66Ga reactions were compared with published data and with theoretical predictions based on the hybrid-precompound model ALICE-IPPE. Thick target yields of67Cu,67Ga (T1/2= 78.3 h) and66Ga (T1/2= 9.4 h) were calculated. Production of67Cu is feasible only at proton energies above 50 MeV. For the target thicknessEp= 70 → 50 MeV, the yield of67Cu amounts to 16.9 MBq/µA·h.
Separation of neptunium and plutonium from acidic medium using 3-phenyl-4-benzoyl-5-isoxazolone
Authors: Mohapatra P. K. , Ruikar P.B. , Manchanda V.K.
Published: September 2005

The extraction behaviour of plutonium (IV) and neptunium (IV) was studied from nitric as well as hydrochloric acid employing 3-phenyl-4-benzoyl-5-isoxazolone (PBI) in toluene as the extractant. The forward extraction in hydrochloric acid medium was carried out in presence of several holding oxidants out of which ammonium meta vanadate was found to give the best results. The stripping behaviour of Np and Pu was studied employing a variety of reagents out of which 0.1 M hydroquinione in 1:1 HCl was the most promising. The separation of Np from Pu under simulated conditions was attempted from hydrochloric acid medium giving a decontamination factor value of >104 and ∼60% Pu recovery.
A statistical study of 238U and 234U/238U distributions in coral samples from the Egyptian shoreline of the north-western Red Sea and in fossil mollusk shells from the Atlantic coast of High Atlas in Morocco: Implications for 230Th/234U dating
Authors: Choukri A. , Reyss J.-L. , Hakam O.K. , Plaziat J. C.
Published: September 2005

In this work, radiochemical analysis results of 126 unrecrystallized coral samples from the Egyptian shoreline of northwestern Red Sea and 120 fossil mollusk shell samples from the Atlantic coast of Moroccan High Atlas at the North of Agadir City in Morocco are presented and discussed. The coral samples were collected in Egypt from the emerged coral reef terraces over 500 km from The Ras Gharib-Ras Shukeir depression (28°10') in the north to Wadi Lahami (north of Ras Banas, 24°10') in the south. The fossil mollusk shells were collected in Morocco from Agadir-Harbour in the south to Tamri village in the north extending over about 50 km. The statistical distributions of results (238U content, 234U/238U activity ratio and ages) obtained on the dated materials in the two different regions were compared for three fossil sea levels corresponding to three different climatic stages (Holocene, 5e, 7 and/or 9) in the aim to establish methodological criteria for judging validity of the measured ages.

For corals, 238U content varies in narrow interval around the same average value of 3 ppm for the three sea levels, the calculated initial 234U/238U values are in agreement with the actual sea water ratio (1.15) with some values slightly higher than for the older sea levels. The obtained ages are in good agreement with the ages reported previously for the three emerged fossil sea levels on unrecrystallized corals by alpha spectrometry and by mass spectrometry.

For mollusk shells, except for Holocene sea level, 238U and initial 234U/238U activity ratios vary for the older levels in wide intervals, independent of species and calcite contents of samples. The high 238U contents and 234U/238U activity ratio are due eventually to a post-incorporation of secondary uranium from sea water or from continental waters drained away rivers. This incorporation leads to a rejuvenation of mollusk shell ages and is responsible for the wide dispersion of their apparent ages according to the mode and the timing of uranium introduction.
Radiochemical neutron activation analysis of total trace tin and determination of its differentiated compounds in aquatic biota
Authors: Amer H. A. , Shawky S.
Published: September 2005

The optimization of extraction and determination of trace tin using radiochemical neutron activation analysis (RNAA) in selected aquatic specimen (algae, fish, mussels) is described. Neutron activation analysis (NAA) using the induced 117mSn (13.6 days) or 113Sn (115 day) nuclides is in principle a sensitive method for determination of total trace tin. However, due to the high contents of arsenic (As) in most marine matrices, neutron irradiation induces high levels of 76As (26.3 h) in comparison to weak 117mSn activities. Selective removal of As by absorption on Acidic Aluminum Oxide (AAO) would be advantageous and reduce the activities required to be handled during tin purification. It was found that perchloric acid medium is the best eluent for separating Sn from As, whereas sulfuric acid and a mixture of the two were not as effective. The standard radiochemical separation procedure based on solvent extraction and purification of tin iodide in toluene from sulfuric acid-potassium iodide (KI) medium with recoveries ranging between 90%–95% is applied. Interferences from the 47Ca/47Sc decay and 199Au with similar gamma energies were effectively removed by the liquid/liquid separation. Comparing the total tin content in freeze-dried samples with the total organotin content in fresh samples shows that the drying process has changed the tin species pattern of the material. The total butyltin content represents 60% and 90% of the total tin content in eel-pout and bream muscles, while it represents about 76%–83% and 58%–88% in mussels and algae, respectively.
Production and radiochemical separation of rhodium-105 for radiopharmaceutical applications
Authors: Unni P. R. , Pillai M.R.A.
Published: September 2005

Production of no carrier added105Rh by thermal neutron irradiation of natural Ru target and ist radiochemical separation to obtain radionuclidically and radiochemically pure species is described. Irradiation planning, post irradiation chemical separation of105Rh from ruthenium and irridium radionuclidic contaminants are discussed in detail. 100 mg of natural Ru was irradiated in a thermal neutron flux of 3 × 1013 neutrons/cm2/s for 7 days. Irradiated target was disolved in an mixture of KIO4and KOH in presence of water. Solvent extraction with CCI4was used for removal of97Ru and103Ru, whereas solvent extraction with TBP was used for the removal of traces of192Ir impurity. Different radiochemical separation techniques were tested for the recovery of105Ru and ist final purification from the accompanying radionuclidic impurities. The salts associated with the product were subsequently removed by fractional precipitation and by cation exchange chromatography. The radionuclidic purity of the105Rh separated was estimated by gamma ray spectrometry; no radionuclidic contamination was observed. The radiochemical purity of the105RhCI3was acsertained bx paper chromatography and paper electrophoresis. Production of no carrier added105Rh by thermal neutron irradiation of natural Ru target and ist radiochemical separation to obtain radionuclidically and radiochemically pure species is described. Irradiation planning, post irradiation chemical separation of105Rh from ruthenium and irridium radionuclidic contaminants are discussed in detail. 100 mg of natural Ru was irradiated in a thermal neutron flux of 3 x 1013 neutrons / cm2/ s for 7 days. Irradiated target was disolved in an mixture of KIO4and KOH in presence of water. Solvent extraction with CCI4was used for removal of97Ru and103Ru, whereas solvent extraction with TBP was used for the removal of traces of192Ir impurity. Different radiochemical separation techniques were tested for the recovery of105Ru and ist final purification from the accompanying radionuclidic impurities. The salts associated with the product were subsequently removed by fractional precipitation and by cation exchange chromatography. The radionuclidic purity of the105Rh separated was estimated by gamma ray spectrometry; no radionuclidic contamination was observed. The radiochemical purity of the105RhCI3was acsertained bx paper chromatography and paper electrophoresis.
Transmutation of239Pu and other nuclides using spallation neutrons produced by relativistic protons reacting with massive U- and Pb-targets
Authors: Brandt R. , Westmeier Wolfram , Odoj R. , Adam J. , Adloff J. C. , Balabekyan A. , Barabanov M. Y. , Bradnova V. , Chaloun P. , Debeauvais M.
Published: September 2005

Experimental studies on the transmutation of some long-lived radioactive waste nuclei, such as129I,237Np, and239Pu, as well as on natural uranium and lanthanum were carried out at the Synchrophastron of the Laboratory for High Energies at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The radioactive targets (I, Np and Pu) were contained in weld-sealed aluminium holders produced by the Institute of Physics and Power Engineering, Obninsk, Russia. Spallation neutrons were produced by relativistic protons with energies in the range of 0.5 GeV≤Ep≤1.5 GeV interacting with 20 cm long uranium or lead target stacks. The metallic targets were surrounded by 6 cm thick paraffin moderators. The uranium and lanthanum samples were positioned on the outside of the moderator surface and typically contained approximately 0.5 to 1.0 gram of uranium or lanthanum. The highest fluence of spallation neutrons was observed in the region of 5 to 10 cm downstream the entrance of the primary beam into the metallic target, rather independent of the target material or the proton energy. The results obtained by nuclear chemistry methods were supplemented by SSNTD (Solid State Nuclear Track Detector) studies. Consistent and systematic results ofB-values and spectral distributions for neutrons have been found. From the experimentally observed transmutation rates one can extrapolate that in a subcritical nuclear power assembly (or "energy amplifier") using a 10 mA proton beam of 1 GeV onto a Pb-target as used here, one can transmute within one month in one gram of sample about 3 mg129I, 21 mg237Np, 3.3 mg238U, and 200 mg239Pu. Rather similar results have been found by another group for129I and239Pu. Observations show that the transmutation rates increase almost linearly with the proton energy in the energy interval 0.5 GeV up to 7.4 GeV. These findings are largely confirmed by model calculations using the LAHET- and DCM/CEM-codes.
Sample preparation methods for the determination of plutonium and strontium in environmental samples by low level liquid scintillation counting and α-spectrometry
Authors: Solatie D. , Carbol P. , Hrnecek E. , Jaakkola T. , Betti M.
Published: September 2005

Two different methods – leaching and microwave assisted total dissolution – have been exploited for the treatment of environmental samples for the determination of plutonium and strontium. Leaching applied to reference materials demonstrated the procedure to be applicable for the recovery of technogenic Pu and Sr from environmental samples.

For the measurement of the alpha emitters of plutonium, co-precipitation with calcium oxalate and ferric hydroxide and separation with anion exchange has been used. For preparation of α-spectrometry sources, co-precipitation with NdF3on a membrane filter or electro-deposition using the (NH4)2C2O4/HCl method have been tested. The beta emitter241Pu was measured by liquid scintillation counting. Pu isotope concentrations determined in the reference materials agreed well with the certified concentrations.

90Sr was measured in the leachate solutions from environmental samples collected close to a nuclear facility and from reference materials, after separation from the other leached elements, by liquid scintillation counting and Cherenkov counting. The90Sr-concentrations determined in the reference materials agreed well with the certified concentrations. In the samples collected close a nuclear facility (soil, grass and sheep faeces),90Sr was found at higher levels, which could also be correlated with the location of the sampling.
Studies on the extraction of uranium by N-octanoyl-N-phenylhydroxamic acid
Authors: Saha B. , Venkatesan K. A. , Natarajan R. , Antony M. P. , Vasudeva Rao P. R.
Published: September 2005

N-octanoyl-N-phenylhydroxamic acid (OHA) has been prepared by partial reduction of nitrobenzene with Zn dust/NH4Cl, followed by acylation with n-octanoyl chloride. Structure of OHA was confirmed by 1H NMR, IR spectra and CHNS microanalysis. The extraction of uranium by OHA has been studied as a function of pH, temperature and concentration of OHA. The extraction of uranium was found to increase with increase in pH. Uranium forms a 1:2 complex with OHA. IR Spectra & NMR Spectra of the uranium-OHA complex and slope analysis obtained from extraction studies indicated that the extraction of uranium was due to the formation of a chelate. The enthalpy change accompanied by the extraction of uranium by OHA has been obtained by temperature variation method. The extraction process was found to be endothermic at pH 2 and exothermic at pH 6.
Transport of U(VI), Th(IV) and lanthanides through cation exchange membrane impregnated with HDEHP-kerosene using electric field
Authors: Gasser M. S. , Zaki E. E.
Published: September 2005

Electrodialysis has been investigated as a method to enhance the transport of U(VI), Th(IV) and lanthanides through Nafion cation exchange membrane I and impregnated with HDEHP-kerosene II. The recovery factor of U(VI) through Nafion cation exchange membrane with and without the applied electric field was 0.8 and 0.14, respectively. The transport process of U(VI) through ion exchange membrane was studied as a function of variation of nitric acid concentration in the feed solution, HDEHP concentration in the membrane stripping solution concentration, pH of the feed solution and effect of electric field. From this study the cationic flux of U(VI) through Nafion I and impregnated with HDEHP-kerosene II was 5.2 × 10−8 and 8.7 × 10−8 g eq cm−1, respectively. The technique of electrodialysis is efficient in preconcentration of U(VI) to 2.8 fold of the initial concentration. The recovery factors of lanthanide elements La(III), Eu(III) and Er(III) through the systems I and II were 0.8 in system I and 0.86, 0.8 and 0.73 in system II, respectively. The recovery factors of La(III), Eu(III), Er(III) and U(VI) through the system II were 0.82, 0.75, 0.71 and 0.27, respectively. The recovery factor of Th(IV) and U(VI) at pH = 1.5 was found to be 0.99 and 0.3, respectively.
Partial and total thermal neutron capture cross sections for non-destructive assay and transmutation monitoring of 99Tc
Authors: Molnár G. L. , Belgya T. , Révay Zs. , Qaim Syed M.
Published: September 2005

Accurate partial gamma-ray production cross sections were determined for the prompt and radioactive product decay gamma rays following cold neutron capture in 99Tc. They can be used for non-destructive assay of technetium by prompt gamma activation analysis (PGAA) and neutron activation analysis (NAA), offering orders of magnitude higher analytical sensitivities than passive gamma-ray counting. A lower limit of 21.21 ± 0.17 b was also deduced for the thermal-neutron-capture cross section.
Control of plutonium dioxide solubility by amorphous tetrahydroxide: A critical review of the model
Authors: Haschke J. M. , Bassett R. L.
Published: September 2005

Solubility data for dissolution of plutonium dioxide and tetrahydroxide in laboratory and natural waters are compared with results of modeling calculations. Evaluation shows that selection of metastable Pu(OH)4as the solubility-controlling solid results in predicted steady-state plutonium concentrations that are not conservative and oxidation-state distributions that are inconsistent with observation. Although only the presence of Pu(III) and Pu(IV) is predicted at measured solution potentials, Pu(V) and Pu(VI) predominate (>95%) in steady-state solutions at pH 1–9. Behavior is inconsistent with thermodynamic and kinetic constraints of the conceptual chemical model and a strong dependence of experimental equilibrium expressions on the amount of solid hydroxide in the steady-state solution suggests that dissolution of plutonium oxide is not an equilibrium process.
Technetium migration in fluoroapatite during thermal annealing
Authors: Gaillard C. , Chevarier N. , Millard-Pinard N.
Published: September 2005

Technetium migration was investigated apatite a possible nuclear wastes conditioning materials.99mTc was introduced into fluoroapatite by ion implantation. The analysis of implanted profile evolution under samples treatment allows to identify the migration process as a bulk diffusion. The observed Tc release is correlated to the oxidation of Tc by interaction with air at the sample surface.
Uranium release from boom clay in bicarbonate media
Authors: Wang L. , Dierckx A. , De Cannière P. , Maes A.
Published: September 2005

The release of natural uranium from Boom Clay was studied to better understand the mechanisms governing the solid-liquid partitioning of uranium. Batch leaching experiments suggested that the portion of natural uranium released from clay is associated with colloids at a low bicarbonate concentration prevailing in Boom Clay. At increased bicarbonate concentrations, uranium was present predominantly as dissolved species indicating a formation of uranium carbonate complexes. Thein situaqueous uranium concentration,i.e., the concentration in the pore waters collected by piezometers was found to be 2 to 3 orders of magnitudes lower than the one measured by the batch techniques. These results illustrated that the batch techniques may cause a remobilization of uranium containing colloids from clay surfaces into solution when clay is suspended, agitated, and mechanically perturbed. These colloids are attributed to artefacts and are not considered to existin situbecause of the high compaction of Boom Clay. Due to the presence of colloids, a laboratory derived solid-liquid partitioning coefficient is not equivalent to and cannot simply be converted to the distribution coefficientKdcurrently used in performance assessment calculations.
Formation of secondary phases after long-term corrosion of simulated HLW glass in brine solutions at 190 °C
Authors: Zimmer P. , Bohnert E. , Bosbach Dirk , Kim Jae-Il , Althaus E.
Published: September 2005

The behavior of rare earth elements (REE) as chemical analogues for actinides during glass corrosion was studied with static long-term batch experiments (7.5 years) at 190 °C. Corrosion tests were carried out using a simulated inactive high level waste (HLW) glass powder. Two different highly concentrated salt solutions (NaCl-rich and MgCl2-rich) have been used to simulate the potential corrosion by aqueous solutions in geological salt formations. Samples with surface-to-volume ratios (S/V) of 1000 m−1and 10000 m−1were investigated. The chemical composition of the aqueous solution and the formation of secondary phases at the glass/solution interface as well as their elemental composition, especially with respect to the behavior of REE was studied. The glass corrosion behavior and secondary phase formation was significantly different in the two brines. In the MgCl2-rich salt solution, with a final pH < 3.5, hydrous Mg-silicates and (Ba,Sr)SO4solid solutions with considerable amounts of Sr (up to 15 wt.%) have been observed. Further, REE-sulfates and REE-molybdates with an indication of dissolution (etch pits) as secondary phases could be identified. In the NaCl-rich solution with a final high pH, REE-containing hydrous silicates (up to 35 wt.%) and (Ba,Sr)SO4solid solutions with small amounts of Ce (up to 5 wt.%) have been observed. Frequently observed Ca-molybdates (powellite) did not contain detectable amounts of REE.
Sorption behaviour of Am on precorroded HLW glass in water and brines
Authors: Luckscheiter B. , Nesovic M.
Published: September 2005

In the alteration layer of HLW glasses corroded in aqueous solutions, less soluble elements like REE, actinides and other elements are retained by sorption or by formation of secondary alteration products controlling the solution concentrations. In order to quantify the sorption effect on the retention of metal ions, first sorption tests with U, Th and Eu have been performed using precorroded, simulated HLW glass as substrate.

To demonstrate that the sorption behaviour of Eu is also representative for homologue trivalent actinides additional sorption tests were performed with Am241 in deionized water, NaCl and MgCl2 brine. Distribution ratios R
s (R
s=Amsorb/ Amsol× V/m) for Am were found independent of the starting concentration in the pH range 2 to 6. At higher pH, a high amount of Am-containing colloidal particles were detected. The R
s values of Am show a strong increase with pH, quite similar to the R
s values of Eu. In general, the sorption behaviour of Eu and Am is very similar in deionized water and in brines. Clay minerals formed in the gel layer as secondary phases during long-term glass corrosion are assumed to act primilary as strong sorbents. Therefore, the sorption of REE and Am onto synthetic poor crystalline smectite precursors and a "well crystallized" natural smectite is compared with the findings obtained from precorroded glass. The sorption of Am on the precorroded glass is found to be much stronger than the retention on the investigated pure clay phases, indicating a different number of active sites or occurance of a different sorption mechanism.
Molecular fluorescence spectroscopy and mixture analysis for the evaluation of the complexation between humic acid and UO2
2+
Authors: Saito Takumi , Nagasaki S. , Tanaka S.
Published: September 2005

Humic acid (HA) was fractionated by gel permeation chromatography and the complexation of the obtained three fractions with UO2
2+ was examined by synchronous fluorescence spectroscopy combined with SIMPLISMA, which is one of the mixture analysis methods. Most of the fluorescence of HA resulted from the lowest molecular weight fraction, and the quenching behavior of this fraction was similar to that of unfractionated HA. After the spectral resolution by SIMPLISMA, two components, which were differently quenched with UO2
2+, were extracted for both cases. The complexing parameters, the apparent stability constant and the concentration of complexing sites, were evaluated for each component and compared between unfractionated HA and the lowest molecular weight fraction.
Investigation on uranyl interaction with bioactive ligands. Synthesis and structural studies of the uranyl complexes with glycine and N-(2-mercaptopropionyl)glycine
Authors: Keramidas A. D. , Rikkou M. P. , Drouza C. , Raptopoulou C.P. , Terzis A. , Pashalidis I.
Published: September 2005

Three new uranium(VI) compounds have been prepared with glycine (Hgly), N-(2-mercaptopropionyl)glycine (Hmpg) and 2,2′-dithiobis(N-propionylglycine) (tpg). The crystal structure of [UO2(Hgly)2Cl2] has been solved, revealing the uranium atom to be seven-co-ordinated. The two zwitterionic glycines are coordinated to uranium atom by the carboxylate groups, one in a monodentate and the other in a bidentate mode. Solid state studies and low temperature 1H, 13C, 2D COSY and HMQC solution NMR spectra of the [UO2(mpg)(CH3COO)], show that mpg coordinates uranium atom by the carboxylate group.
Complex formation of Eu(III) with humic acid and polyacrylic acid
Authors: Kubota Takumi , Tochiyama Osamu , Tanaka K. , Niibori Yuichi
Published: September 2005

With the intention of estimating the effect of the heterogeneous composition in the humic acid separately from its polyelectrolyte effect, comparative study on the interaction of Eu(III) with humic acid and polyacrylic acid has been carried out by the solvent extraction method with 10−3M TTA and 10−3M TBP in xylene at various total concentrations of Eu(III) (10−8M to 10−5M), pcH(5.0 to 5.5) and ionic strengths (0.02 to 1.0 M NaClO4). The interaction has been discussed in terms of the apparent complex formation constants, βα= [ML]/([M][R]), where [M] and [ML] are the concentrations of free and bound Eu3+ion and [R] is the concentration of dissociated proton exchanging site. For both humate and polyacrylate, logβαincreased with pcHor the degree of ionization and decreased with ionic strength. The Eu3+ion concentration had no appreciable influence on the complex formation of Eu(III)-polyacrylate, and the values of logβαwere obtained to be 7.57 ± 0.05 (I= 0.1, pcH= 5.53), 7.13 ± 0.04 (I= 0.1, pcH= 5.20), 6.68 ± 0.04 (I= 1.0, pcH= 5.54) and 5.61 ± 0.09 (I= 1.0, pcH= 4.73). On the other hand, logβαof humate remarkably decreased with the Eu3+ion concentration; from 9.32 ([Eu3+] = 10−11.9M) to 7.20 ([Eu3+] = 10−7.5M) at pcH= 5.53 in 0.02 M NaClO4, from 8.63 ([Eu3+] = 10−12.5M) to 6.35 ([Eu3+] = 10−7.2M) at pcH= 5.53 in 0.1 M and from 7.59 ([Eu3+] = 10−10.7M) to 5.20 ([Eu3+] = 10−7.0M) at pcH= 5.52 in 1.0 M. The observed dependence of logβαof humate on the concentration of metal ion strongly suggests the heterogeneity of the complexing sites (the coexistence of weak and strong binding sites) in the humic acid.
XAS study of technetium(IV) polymer formation in mixed sulphate/chloride media
Authors: Vichot L. , Ouvrard G. , Montavon G. , Fattahi Massoud , Musikas C. , Grambow Bernd
Published: September 2005

X-ray absorption spectroscopy has been used to establish polymer formation of Tc(IV) in aqueous solutions of Na+SO42−and Na+Cl−/SO42−.

As the molybdenum chemistry show similarities to that of technetium, we used MoO2as a reference to model our technetium species. Fitting of TcO2·xH2O with this model led to a good correlation with the literature data: (Tc-Tc=2.53 Å, Tc-O=1.87-1.98 Å).

In aqueous solution, some polymers are formed regardless to the nature of the media composition: Tc-Tc=2.50 ± 0.02 Å. The general structure is in agreement with a first coordination shell containing 6 O. The modelling shows that, in the first coordination shell, there is no chloride ligand. The observed geometries are close to those found for TcO2·xH2O, hence the unknown aqueous species must be considered as a precursor of the solid technetium dioxide.

Combination of these results with XANES led to attribute TcnIVOp(4n-2p)+(H2O)qwith n>2 to the species.
The effects of alpha-radiolysis on UO2 dissolution determined from electrochemical experiments with 238Pu-doped UO2
Authors: Stroes-Gascoyne S. , King F. , Betteridge J. S. , Garisto F.
Published: September 2005

The long-term stability of spent nuclear fuel under deep geologic repository conditions will be determined mostly by the influence of α-radiolysis, since the dose-rate for α-radiolysis will exceed that for γ/β-radiolysis beyond a fuel age of ∼100 years and will persist for more than 10000 years. Dissolution rates derived from studies with currently available spent fuel include radiolysis effects from γ/β- as well as α-radiolysis. The use of external α-sources and chemically added H2O2 in UO2 studies has provided much information on the basic chemistry/electrochemistry of α-radiolysis effects on UO2 fuel dissolution. Here, alpha-radiolysis effects were measured directly by performing electrochemical experiments with α-doped UO2. The 238Pu-doped UO2 pellets, produced by milling, pressing and sintering, had activities of approximately 0.01 and 0.1 Ci/g. Discs cut from these pellets were fabricated into electrodes. Corrosion potentials (Ecorr) were measured for these electrodes, in glass cells containing de-aerated 0.1 M NaClO4 (pH 9.5) for periods up to 1600 h. The effects of carbonate and Fe(II) on Ecorr values were also investigated. Preliminary results showed that Ecorr values correlated with doping levels, and were slightly higher than Ecorr values obtained with UO2 electrodes in the presence of external α-sources. The presence of carbonate reduced Ecorr values considerably. Addition of Fe(II) caused generally small reductions in Ecorr values, suggesting that Fe(II) affects the dissolution process, either by scavenging radiolytic oxidants, reducing oxidized surface states, or reducing dissolved U(VI). These effects were often transient due to depletion of the added Fe(II). Accurate dissolution rates could not be determined from measured solution and surface concentrations because of material entering the solutions during the electro-reduction procedure, probably due to the dissolution of fines present on the electrode surface after polishing. Experiments are continuing in order to confirm the preliminary findings, with greater attention being paid to determining accurate dissolution rates.
Radiation-chemical effects in the near-field of a final disposal site: role of bromine on the radiolytic processes in NaCl-solutions
Authors: Ershov B. G. , Kelm M. , Janata E. , Gordeev A. V. , Bohnert E.
Published: September 2005

The oxidation of Br−by Cl2−is investigated by gamma pulse radiolysis in aqueous solutions of NaCl and NaBr. Depending on the ratio of the concentration of Br−to Cl−, the main product being observed is either Cl2−, ClBr−or Br2−. The mixed radical anion ClBr−exhibits a broad absorption band at 350 nm with ε350=9300 dm3mol−1cm−1. The rate constants of the equilibrium Cl2−+ Br− ClBr−+Cl−are determined to be kf=4×109dm3mol−1s−1and kb=1.1×102dm3mol−1s−1. The formation of the Cl3−(λmax=220 nm), Cl2Br−(λmax=230 nm) and ClBr2−(λmax=245 nm) ions in the radiation-chemical oxidation of Cl−and Br−ions in an aqueous solution was observed by pulse radiolysis, and its mechanisms of appearance and the equilibrium constants were determined.
Structure of uranium sorption complexes at montmorillonite edge sites
Authors: Hennig C. , Reich T. , Dähn R. , Scheidegger A. M.
Published: September 2005

Extended X-ray absorption fine structure (EXAFS) spectroscopy at the uranium LIII-edge was used for determining the structural environment of aqueous uranyl sorbed onto montmorillonite. The study reveals that uranyl uptake at pH ∼5-∼7 and at an initial uranyl concentration of 5×10−5M takes place at amphoteric surface hydroxyl sites as inner-sphere complex. The measured bond distances between uranium and the equatorial oxygen atoms are in the range of 2.34 Å and 2.37 Å indicating an inner-sphere coordination. At ∼3.4 Å the presence of a U-Al backscattering pair was determined. This backscattering pair indicates that the binding of the uranyl unit to amphoteric surface hydroxyl sites occurs preferred as a bidentate inner-sphere complex on aluminol groups.
Sorption of several safety relevant radionuclides on granite and diorite – a potential repository host rock in the Taiwan area
Authors: Hsu C.-N. , Wei Y.-Y. , Chuang J.-T. , Tseng C.-L. , Yang J.-Y. , Ke C.-H. , Cheng H.-P. , Teng S.-P.
Published: September 2005

The geological survey of natural barriers plays a critical role in determining the suitability of a site for the final disposal of high-level radwaste. This study focused on the characterization of sorption and the determination of distribution coefficients of several safety relevant radionuclides. Both batch tests and polar-microscopy/autoradiography were employed for analyzing and estimating of the sorption of nuclides on one potential host rock in the Taiwan area, which is composed of mostly granite and little diorite. Nuclides investigated were Co, Sr, Cs, U, I, and Am. De-ionized water and synthetic seawater were applied to study nuclide sorption at various concentrations. The distribution coefficients obtained based on the two-week batch tests indicated that the sorption of Co, Sr, Cs, and U on each rock sample was greater in de-ionized water than in synthetic seawater. In addition, sorption onto a specific host rock depended on microscopic heterogeneity. The photos obtained from polar-microscopy/autoradiography showed that biotite is the principal mineral component that is responsible for the sorption of137Cs and90Sr onto granite and diorite.
Sorption behaviour of caesium on a bentonite sample
Authors: Hurel C. , Marmier N. , Sèby F. , Giffaut E. , Bourg A. C. M. , Fromage F.
Published: September 2005

Sorption of elements like Cs on clay is one of the principal processes delaying their release from deep repositories of nuclear wastes into the environment. The sorption processes taking place between non-purified natural clay material (bentonite) and synthetic groundwater (containing Ca, Mg, Na, K and carbonates) were therefore studied experimentally and modelled for Cs to determine whether thermodynamic computer codes capable of predicting the behaviour of this element in natural systems might be developed. The model used, based on the properties of a pure montmorillonite phase, incorporates the surface reactions for natural major ions and sorbing cations but does not have any adjustable parameters. The weight of each parameters used in the model is assessed. Surface reactions are classified as either major or minor, and a simplified model of Cs sorption that considers only the major processes is proposed. This simplified model might correspond to the less sophisticated thermodynamic model included in coupled geochemistry-transport models.
Specific interaction of cesium with the surface of calcium silicate hydrates
Authors: Viallis-Terrisse H. , Nonat A. , Petit J.-C. , Landesman Catherine , Richet C.
Published: September 2005

The sorption of cesium at the calcium silicate hydrates (CSH) surface was investigated, both through sorption isotherm data and by solid-state NMR experiments. The sorption ability of CSH towards cesium is favored for low solid Ca/Si molar ratios, in agreement with the negative surface charge they develop then. A significant proportion of these sorbed cesium cations remains tightly bound to the surface sites forming, in dehydrated CSH, inner-sphere complexes, which can not be removed by alcohol washing. Chloride seems to present a lower affinity for CSH, even for high Ca/Si molar ratios, where the surface charge becomes positive.