bluuebunny/crossref_metadata_2025_split huggingface dataset:
U, Th, Eu and colloid mobility in a granite fracture under near-natural flow conditions
Authors: Schäfer Thorsten , Geckeis Horst , Bouby Muriel , Fanghänel Thomas 
Published: December 2004

Summary
Laboratory core migration experiments were performed in a granite fracture from the Grimsel Test Site (GTS, central Swiss Alps). The flow velocity was varied (46 m yr-1, 94 m yr-1, 187 m yr-1) and solutions with 10-6 mol L-1 U(VI), 10-8 mol L-1 Th(IV) and 10-8 mol L-1 Eu(III) without (cocktail I) and with addition of 2 mgL-1 bentonite colloids (cocktail II) have been injected. Results are compared with those obtained in a field study at the GTS. Flow field-flow fractionation and ultrafiltration measurements show that U(VI) is not colloid borne, different from Th(IV) and Eu(III) which are associated with colloids in both spiked natural groundwaters with and without bentonite colloid addition. The partly unretarded U(VI) migration observed at short contact times (1-2 h) diminished under near-natural groundwater velocities (∼46 m yr-1) and only a weak retardation (R
f=19.5) could be observed. Furthermore, the U(VI) mass recovery decreased with increasing contact time and was as expected unaffected by bentonite colloid addition. A groundwater colloid mediated Th(IV)/Eu(III) migration without bentonite colloid addition could be confirmed in the core experiments but only at fast groundwater flow rates. Experiments at a water flow rate of 94 m yr-1 with cocktail II demonstrated a partially bentonite colloid facilitated transport of Th(IV) and Eu(III) with 27% and 37% mass recovery, respectively. At long tracer residence times in the flow field, no breakthrough of colloidal Th(IV)/Eu(III) could be observed in both runs, indicating the strong dependence of reaction kinetics on their mobility. Reference colloid experiments using fluorescence dye labeled carboxylated polystyrene microspheres (25 nm, 50 nm and 100 nm) revealed in general a higher recovery of smaller colloid size classes increasing with groundwater velocity. Additionally, an earlier peak arrival time of colloids and colloid-associated Th(IV) and Eu(III) was observed with respect to the conservative tracer 3H in all experiments due to pore-size or charge exclusion effects. In general, the colloid recoveries found in the laboratory core experiments are lower than those obtained in the field studies. The decrease of colloid mobility with increasing residence time suggests the occurrence of colloid attachment to the rock surfaces even under the colloid stabilizing groundwater conditions.
In-situ diffusion of HTO, 22Na+, Cs+ and I- in Opalinus Clay at the Mont Terri underground rock laboratory
Authors: Van Loon Luc R. , Wersin P. , Soler J. M. , Eikenberg J. , Gimmi Th. , Hernán P. , Dewonck S. , Savoye S. 
Published: December 2004

Summary
The diffusion properties of the Opalinus Clay were studied in the underground research laboratory at Mont Terri (Canton Jura, Switzerland) and the results were compared with diffusion data measured in the laboratory on small-scale samples. The diffusion of HTO, 22Na+, Cs+ and I- were investigated for a period of 10 months. The diffusion equipment used in the field experiment was designed in such a way that a solution of tracers was circulated through a sintered metal screen placed at the end of a borehole drilled in the formation. The concentration decrease caused by the diffusion of tracers into the rock could be followed with time and allowed first estimations of the effective diffusion coefficient. After 10 months, the diffusion zone was overcored and the tracer profiles measured. From these profiles, effective diffusion coefficients and rock capacity factors could be extracted by applying a two-dimensional transport model including diffusion and sorption. The simulations were done with the reactive transport code CRUNCH. In addition, results obtained from through-diffusion experiments on small-sized samples with HTO, 36Cl- and 22Na+ are presented and compared with the in situ data. In all cases, excellent agreement between the two data sets exists. Results for Cs+ indicated five times higher diffusion rates relative to HTO. Corresponding laboratory diffusion measurements are still lacking. However, our Cs+ data are in qualitative agreement with through-diffusion data for Callovo–Oxfordian argillite rock samples, which also indicate significantly higher effective diffusivities for Cs+ relative to HTO.
Solubility constraints on uranium concentrations in groundwaters of the Tono uranium deposit, Japan
Authors: Iwatsuki T. , Arthur R. , Ota K. , Metcalfe R. 
Published: December 2004

SummaryA key concept underpinning most safety assessments of geological disposal systems for high-level nuclear wastes is that the maximum aqueous concentrations of actinide elements released from the waste will be limited by the solubility of the corresponding tetravalent oxide or hydrous oxide. The validity of this concept for U is evaluated in the present study using hydrochemical and mineralogical data from the Tono uranium (U) deposit in Gifu Prefecture, Japan. In addition, the long-term stability of U mineralization in the Tono deposit is assessed in terms of plausible range of U solubilities in paleogroundwaters migrating through the deposit.A thermodynamic evaluation of the aqueous-speciation and solubility behaviour of U indicates that U concentrations in the coexisting groundwaters greatly exceed the solubility of both uraninite [UO2(c)] and coffinite [USiO4(c)]. The dissolved U concentrations appear instead to be controlled by the solubility of amorphous hydrous U(IV) oxide [UO2(am)], which is metastable with respect to uraninite. Mineralogical and microbiological investigations suggest that pH–Ehconditions similar to those observed presently in groundwaters of the lower Toki Lignite-bearing Formation (pH≈8-10;Eh≈-250--410 mV) have been buffered, possibly since the present geological structure formed about 5-0.7 Ma, by microbial sulphate reduction and precipitation/dissolution of calcite. If so, corresponding U concentrations controlled by UO2(am) solubility are calculated to have been in the range of 10-6.1and 10-8.7mol kg-1depending on the possible environmental conditions,i.e.,Eh, pH and carbonate concentration.
Mobility of uranium in tertiary argillaceous sediments – a natural analogue study
Authors: Noseck Ulrich , Brasser Thomas , Rajlich Petr , Laciok Ales , Hercik Mirek 
Published: December 2004

Summary
The aim of the Natural Analogue study at Ruprechtov site (CZ) is to investigate the potential mobility of uranium in tertiary argillaceous sediments under representative long-term conditions. Such sediments often build up the overburden of host rocks for deep geological waste repositories. The Ruprechtov site represents a tertiary basin with argillized volcano-detritic sediments, which is surrounded by granite and underlain by kaolin and granite. U-enrichment mainly occurs in distinct layers of limited thickness on top of the kaolin close to aquiferous horizons and the clay-lignite seams. After a general survey of the site a new set of drillings has been sunk in 2002 in order to investigate the hydraulic, geological and chemical conditions of the area, including detailed investigations of kaolin and granite.
Based on actual results new conceptual models for geological evolution and uranium transport pathways at Ruprechtov site have been developed. There is now strong evidence that U-migration at the site is mainly determined by three different processes: a) diffusion through kaolin, b) advection via fault zones across the kaolin and c) advection through aquiferous layers at the interface kaolin/Tertiary. Uranium source is the so-called Erzgebirgs- (Krušné hory) granite, underlying the Tertiary and kaolin and outcropping at the margins of the Tertiary basin.
Towards a common thermodynamic database for speciation models
Authors: van der Lee Jan , Lomenech Claire 
Published: December 2004

Summary
Bio-geochemical speciation models and reactive transport models are reaching an operational stage, allowing simulation of complex dynamic experiments and description of field observations. For decades, the main focus has been on model performance but at present, the availability and reliability of thermodynamic data is the limiting factor of the models. Thermodynamic models applied to real and complex geochemical systems require much more extended thermodynamic databases with many minerals, colloidal phases, humic and fulvic acids, cementitious phases and (dissolved) organic complexing agents. Here we propose a methodological approach to achieve, ultimately, a common, operational database including the reactions and constants of these phases. Provided they are coherent with the general thermodynamic laws, sorption reactions are included as well. We therefore focus on sorption reactions and parameter values associated with specific sorption models. The case of sorption on goethite has been used to illustrate the way the methodology handles the problem of inconsistency and data quality.
Geochemically derived non-gaseous radionuclide source term for the Asse salt mine – assessment for the use of a Mg(OH)2-based backfill material
Authors: Metz Volker , Schüßler W. , Kienzler B. , Fanghänel Thomas 
Published: December 2004

SummaryThe Asse salt mine was used as a test site for radioactive waste disposal from 1967 to 1978. Low- and intermediate-level waste forms (LLW/ILW) were emplaced, containing a total radionuclide inventory of 3×1015Bq, estimated for reference date January 1, 2005. It is expected that MgCl2-rich brine will enter the emplacement rooms and react with the cemented waste products. Possible microbal degradation of organic waste components in MgCl2-rich brine could produce significant quantities of CO2, resulting in an acidification and consequently in an increase of element solubilities. Application of buffering backfill materials is discussed for closure of the mine. Selection of backfill materials is based on geochemical modeling taking into account the corrosion of the cemented LLW/ILW and degradation of organic waste components. In the present study the evolving geochemical milieu and respective solubilities of Am, Np, Pu, U, Th, Tc, Sr, Cs and I were modeled for each emplacement room. Laboratory experiments were undertaken to selectively verify the modeling predictions.Geochemical modeling leads to the conclusion that Portland cement, a Mg(OH)2-based material and crushed salt can be used in different combinations as backfill materials. According to the predictions Mg(OH)2-based backfill material controls the pH and concentration of dissolved inorganic carbon within ranges that are favorable with respect to actinide solubilities. A source term for radioelements and fission products is derived from a comparison of the respective solubilities and the radionuclide inventories. Calculated solubilities of Th, Pu and U are lower than their inventories. These are controlled by the thermodynamic solubility therefore. Maximum solution concentrations of all other elements are controlled by their inventory.
Simulation of remediation alternatives for a137Cs contaminated soil
Authors: Bea Sergio A. , Carrera Jesús , Soler J. M. , Ayora Carlos , Saaltink Maarten 
Published: December 2004

SummaryWe analyze remediation alternatives for a soil contaminated with137Cs, which sorbs strongly to clay aggregates where water flux is negligible. The mobile portion of the soil (macropores) retains little water and cesium. Some of the remediation alternatives involve infiltration of seawater enriched with KCl, to promote mobilization of Cs through exchange with K. Therefore, a fully coupled reactive transport model is used to test these alternatives. We conclude that flushing is a viable alternative, provided that some recommendations, derived from the modelling exercise are followed. These include high rate periodic infiltration and draining, as well as performing infiltration from independent cells to limit the effect of preferential flowpaths.
Reactive transport modelling of a spent fuel repository in a stiff clay formation considering excavation damaged zones
Authors: De Windt Laurent , Pellegrini Delphine , van der Lee Jan 
Published: December 2004

Summary
The near-field evolution of a spent fuel disposal in a deep stiff clay formation is studied with the coupled chemistry-transport code HYTEC. The study gives an example that such models can be currently used for geometries (2D and 3D) and time scales (100000 y) relevant for performance assessment. The repository consists of short tunnels with MX80 bentonite barriers and cementitious materials for mechanical support. Cesium, iodine and uranium are released from the waste packages considering instant release fractions and congruent dissolution of the fuel pellets. The calculations are carried out with special focus on the excavation damaged zone (EDZ) comparing diffusion process and different advection scenarios in this zone. Cement represents a source of alkaline perturbations but, under the pure diffusion scenario, the alteration of the multi-barrier system remains limited. The presence of the EDZ does not significantly modify radionuclide migration in the pure diffusion case. The advection scenarios, even with very slow flow velocities, illustrate the possibility of preferential pathways through the EDZ for iodine but show almost no effect on the alkaline plume and cesium migration.
AC and DC Conductivity in Nano- and Microcrystalline Li2O : B2O3 Composites: Experimental Results and Theoretical Models
Authors: Indris Sylvio , Heitjans Paul , Ulrich Markus , Bunde Armin 
Published: December 2004

Abstract
We report on impedance measurements of nano- and microcrystalline composites of the Li ion conductor Li2O and the ionic insulator B2O3 as well as their interpretation in the frame of percolation models. In the experimental part, besides the dc conductivity and its dependence on composition and temperature (i.e. its activation energy) also the ac conductivity and its dependence on composition, temperature and frequency (i.e. the conductivity exponent) are presented. Striking differences between the nanocrystalline and the corresponding microcrystalline composites were found. Deviations of the ac from the dc results can be explained by the fact that the experiments probe ion dynamics on different time and thus length scales. In the theoretical part, a continuum percolation model, a brick-layer type bond percolation approach and a Voronoi construction are alternatively used to model the dc behaviour. Based merely on the largely different volume fractions of the interfaces between ionic conductor and insulator grains in the nano- and microcrystalline composites, good overall agreement with the experimental dc results is obtained. The high critical insulator content above which the experimental conductivity vanishes in the nanocrystalline composites suggests the presence of an additional Li diffusion passageway of nanometer length in the interface between nanocrystalline insulator grains.
The Connecting Sea: History, Anthropology, and the Mediterranean
Authors: Driessen Henk 
Published: December 2004

The Corrupting Sea:. Study of Mediterranean History. Peregrine Horden and Nicholas Purcell. Maiden, MA: Blackwell Publishers, 2000. 761 pp.Mediterranean:. Cultural Landscape. Predrag Matvejević. Michael Henry Heim. trans. Berkeley: University of California Press, 1999. 218 pp.. Mediterranean Society. An Abridgment in One Volume. Shlomo D. Goitein. Jacob Lassner. ed. Berkeley: University of California Press, 1999. 503 pp.
"Our" Anthropology of Technoscience?
Authors: Hakken David 
Published: December 2004

The Machine in Me: An Anthropologist Sits among Computer Engineers. Gary Downey. New York: Routledge, 1998. 288 pp.Cyborg Babies: From Techno‐Sex to Techno‐Tots. Robbie Davis‐Floyd and Joseph Dumit. eds. New York: Routledge, 1998. 358 pp.Modest_Witness. Second_Millennium. FemaleMan©_Meets_OncoMouse™. Feminism and Technoscience. Donna Haraway. New York: Routledge, 1996 361 pp.Silicon Second Nature: Culturing Artificial Life in. Digital World. Stefan Helmreich. Berkeley: University of California Press, 1998. 314 pp.
The Pleasure of the Crown: Anthropology, Law and First Nations; Incorporating the Familiar: An Investigation into Legal Sensibilities in Nunavik
Authors: Fiske Jo‐Anne 
Published: December 2004

The Pleasure of the Crown: Anthropology, Law and First Nations. Dara Culhane. Burnaby, BC. Talon Books, 1998.406 pp.Incorporating the Familiar: An Investigation into Legal Sensibilities in Nunavik. Susan G. Drummond. Montreal, Quebec: McGill‐Queen's University Press, 1997.189 pp.
Managing the Historic Rural Landscape; Managing Historic Sites and Buildings: Reconciling Presentation and Preservation
Authors: Hardesty Donald 
Published: December 2004

Managing the Historic Rural Landscape. Jane Grenville. ed. New York: Routledge, 1999.179 pp.Managing Historic Sites and Buildings: Reconciling Presentation and Preservation. Gill Chitty and David Baker. eds. New York: Routledge, 1999.193 pp.
The Stigma of New Guinea — Reflections of Anthropology and Anthropologists
Authors: Iamo Warilea 
Published: December 2004

This examination of Margaret Mead, by an anthropologist from Papua New Guinea, whose people have been the focus of Dr. Mead's research, provides a sorely needed indigenous viewpoint that will benefit western anthropologists.Rising scholars in Papua New Buinea regard Margaret Mead's published studies, and those of most western anthropologists, as being more a reflection of western culture than of the people under study. The distortions created by anthropologists have stripped the indigenous people of their dignity and right to determine their own future.
The Role of Hypoxia-Induced Factors in Tumor Progression
Authors: Vaupel Peter 
Published: December 2004

Abstract

Learning Objectives
After completing this course, the reader will be able to:
Describe hypoxia-induced mechanisms for cell survival. Discuss hypoxia-induced gene expression. Relate hypoxia and glucose metabolism.
Access and take the CME test online and receive 1 hour of AMA PRA category 1 credit atCME.TheOncologist.com
Hypoxia is a common characteristic of locally advanced solid tumors that has been associated with diminished therapeutic response and, more recently, with malignant progression, that is, an increasing probability of recurrence, locoregional spread, and distant metastasis. Emerging evidence indicates that the effect of hypoxia on malignant progression is mediated by a series of hypoxia-induced proteomic and genomic changes activating angiogenesis, anaerobic metabolism, and other processes that enable tumor cells to survive or escape their oxygendeficient environment. The transcription factor hypoxia-inducible factor 1 (HIF-1) is a major regulator of tumor cell adaptation to hypoxic stress. Tumor cells with proteomic and genomic changes favoring survival under hypoxic conditions will proliferate, thereby further aggravating the hypoxia. The selection and expansion of new (and more aggressive) clones, which eventually become the dominant tumor cell type, lead to the establishment of a vicious circle of hypoxia and malignant progression.
The Erythropoietin Receptor and Its Expression in Tumor Cells and Other Tissues
Authors: Farrell Francis , Lee Adrian 
Published: December 2004

Abstract

Learning Objectives
After completing this course, the reader will be able to:
Describe the structure of the erythropoietin receptor. Describe the function of the erythropoietin receptor. Describe the distributions of erythropoietin receptors in normal and tumor tissues.
Access and take the CME test online and receive one hour of AMA PRA category 1 credit atCME.TheOncologist.com
Erythropoietin (EPO) is the primary regulator of erythropoiesis, stimulating growth, preventing apoptosis, and promoting differentiation of red blood cell progenitors. The EPO receptor belongs to the cytokine receptor superfamily. Although the primary role of EPO is the regulation of red blood cell production, EPO and its receptor have been localized to several nonhematopoietic tissues and cells, including the central nervous system (CNS), endothelial cells, solid tumors, the liver, and the uterus. The presence of EPO receptors and the possibility of EPO signaling in these tissues and cells have led to numerous studies of the effects of EPO at these sites. In particular, expression of EPO and the EPO receptor in cancer cells has generated much interest because of concern that administration of recombinant human erythropoietin (rHuEPO) to patients with breast and other cancer cells expressing the EPO receptor may promote tumor growth via the induction of cell proliferation or angiogenesis. However, evidence supporting a growth-promoting effect has been inconclusive. Moreover, several preclinical studies have shown a beneficial effect of EPO on delaying tumor growth. Further, it is conceivable that increased expression of EPO could reduce tumor hypoxia and ameliorate the deleterious effects of hypoxia on tumor growth, metastasis, and treatment resistance. On the other hand, EPO has also been shown to produce an angiogenic effect in vascular endothelial cells in vitro. However, there is no evidence that these effects occur in vivo to promote tumor growth. EPO and EPO receptors are expressed in neural tissue, and they are upregulated there by hypoxia. Animal studies have shown that administration of epoetin alfa (an rHuEPO) reduces tissue injury due to ischemic stroke, blunt trauma, and experimental autoimmune encephalomyelitis. These findings suggest that epoetin alfa may provide a therapeutic benefit in patients with stroke, trauma, epilepsy, and other CNS-related disorders. Clearly, further study of EPO and the EPO receptor in nonhematopoietic tissue is warranted to determine the potential therapeutic usefulness of rHuEPO as well as to determine the signaling pathway responsible for its effect in vivo.
Tumor Hypoxia: Causative Factors, Compensatory Mechanisms, and Cellular Response
Authors: Vaupel Peter , Harrison Louis 
Published: December 2004

Abstract

Learning Objectives
After completing this course, the reader will be able to:
Explain the effect of hypoxia on resistance to treatment. Describe the causes of tumor hypoxia. Characterize cellular response to hypoxia.
Access and take the CME test online and receive 1 hour of AMA PRA category 1 credit at CME.TheOncologist.com
Hypoxia is a characteristic feature of locally advanced solid tumors resulting from an imbalance between oxygen (O2) supply and consumption. Major causative factors of tumor hypoxia are abnormal structure and function of the microvessels supplying the tumor, increased diffusion distances between the nutritive blood vessels and the tumor cells, and reduced O2 transport capacity of the blood due to the presence of disease- or treatment-related anemia. Tumor hypoxia is a therapeutic concern since it can reduce the effectiveness of radiotherapy, some O2-dependent cytotoxic agents, and photodynamic therapy. Tumor hypoxia can also negatively impact therapeutic outcome by inducing changes in the proteome and genome of neoplastic cells that further survival and malignant progression by enabling the cells to overcome nutritive deprivation or to escape their hostile environment. The selection and clonal expansion of these favorably altered cells further aggravate tumor hypoxia and support a vicious circle of increasing hypoxia and malignant progression while concurrently promoting the development of more treatment-resistant disease. This pattern of malignant progression, coupled with the demonstration of a relationship between falling hemoglobin level and worsening tumor oxygenation, highlights the need for effective treatment of anemia as one approach for correcting anemic hypoxia in tumors, and in so doing, possibly improving therapeutic response.