bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation of Differentiating Human Epidermal Cells on Basement Membrane Matrigel: Potential for use as Autografts in Recurrent Ulcerative Lesions
Authors: Walker-Jones Dorothy G. , Reindorf C. A. , Massac E. , Adekile A. D. , Hall M. G. , Nunez A. I.
Published: March 2011

The successful use of in vitro-generated skin autografts in the treatment of burns in humans (Green and O'Connor, 1984) has advanced the potential for application in the treatment of recurrent ulcerative lesions that occur in some patients with sickle cell disease and other disorders. Conventional grafts frequently break down in these patients, requiring repeated grafting that may eventually result in the lack of suitable donor sites. Preliminary studies show that Type I collagen (Collistat) promotes healing of sickle cell-lesions but with extensive scarring and loss of pigmentation (Adekile et al., 1987). Therefore, the primary aim of this study was the development of a culture procedure for the rapid generation of differentiating human epidermal cells on a biomatrix for use in conjunction with the Collistat, and later, the establishment of a frozen culture bank. Dispasefollowed by trypsin-dissociated inner epidermal cells from dermatome sections of skin of adult patients undergoing elective plastic surgery were cultured on basement membrane-derived Matrigel (Collaborative Research, Inc.) coated onto plastic coverslips. Growth was established in RPMI1640 or IMEM supplemented with insulin, transferrin, hydrocortisone and bovine pituitary extract or Keratinocyte Growth Medium (KGM)a nd from 0.5–2.0% fetal bovine serum. The epidermal cells exhibited active migration and the formation of bi- and tri-layered aggregates by day 3. Large multilayered aggregates were produced in KGM with 1.16 mM CaCl2 added. Electron microscopic observations revealed increased numbers of desmosomal junctions, interdigitations and apical-basal polarity in these aggregates. A distinguishing feature ofthese and other cells grown on Matrigel is the absence of the degree of spreading that is characteristic of cells grown on plastic. It is noteworthy that the epidermal cells did not invade through the Matrigel.
Dimac: A New Delivery System for Silver Sulfadiazine
Authors: Miller Linden M. , Hansbrough John F.
Published: March 2011

Wound care for burn victims is painful and tedious, but necessary to avoid the ever-present problem of infection. In an effort to circumvent daily dressing changes while ensuring optimal wound protection, DIMAC, a new drug delivery system for the commonly used topical antimicrobial silver sulfadlazine, has been developed. When incorporated into the delivery system, silver sulfadiazine is released in a sustained fashion. The results of an evaluation of the safety and efficacy of DIMAC in the treatment of full-and partial-thickness burn wounds are described here. DIMAC, left In place for up to 4 days, appears to be as effective as twice-daily cleansing and application of silver sulfadiazine cream.
The Feasibility of a Semiconductor-Laser Glucose-Detection System for Insulin-Pump Therapy
Authors: Arrieta I. C. , Burk D. E. , Batich C.
Published: March 2011

A potentially implantable semiconductor-laser-based sensor is demonstrated to be feasible for glucose detection at concentrations found in the human blood. In the system, the monochromatic, linearly polarized light from a diode laser is directed into an external cavity with a second diode laser at the far end. The cavity is filled with a glucose solution of varying physiological concentrations. The interference of the rotated, polarized light from the first diode laser with that of the second laser is monitored by a photodiode, forming an optoelectronic pair with the first diode laser. A variation in glucose concentration of 0.1 to 0.3 g/dl results in a 5% variation in the photodiode current. This variation is sufficient to provide feedback to an insulin pump.
A Review of Fracture Mechanics in Compact Bone
Authors: Moyle David D.
Published: March 2011

A review of the literature of the past twenty years on the measurements of fracture properties of compact bone, including measurements of critical stress intensity factors, critical strain energy release rates, measurements of “surface free energies” by impact tests, work of fracture tests and other methods, with an emphasis on the relation of fracture measurements to microstructure is presented. Recent results from the author's laboratory on the relation of work of fracture measurements to specimen size and microstructure are presented.
Finite Element Analysis in Orthopaedics
Authors: Koeneman James B.
Published: March 2011

Predicting the stress state in bones is important to the understanding of bone remodeling and the long-term reliability of total joint implants. Beam theory, 2-D and 3-D finite element analysis have been used to calculate stress distributions. These finite element analyses of bone structures are progressing from crude models for which the clinical relevance has been questioned to an important tool which is necessary to understand stress related bone changes.
The Study of Interface Bone Formation Resulting from the Use of Intraosseous Titanium Implants
Authors: Boyne Philip J.
Published: March 2011

The histopathologic characteristics of interface phenomena existing along the surfaces of intraosseous metallic implants has been the subject of much discussion in relating the composition and configuration of implant fixtures to maximal osteointegration. (1,2) The purpose of this study was to evaluate and characterize host bone changes to various types of intraosseous metal implants placed in the femurs of six Papio anubis baboons. We wished to evaluate changes in recipient site bone remodeling which could be related to the specifics of configuration and type of metal implant used.
Microstructure and Elastic Properties of Dental Resin and Resin-Based Glass-Reinforced Composites: XRD, SEM and Ultrasonic Methods
Authors: Singh Surendra , Katz J. Lawrence , Antonucci J. , Penn R. W. , Tesk J. A.
Published: March 2011

The load-bearing ability of dental restorative materials under cyclic high-stress applications depends upon mechanical properties established by the composition and microstructure. The microstructure and the elastic properties of neat resin and two resin-based glass-reinforced composites have been studied. The microstructure of these materials has been examined using x-ray diffractometry (XRD), scanning electron microscopy (SEM) including energy dispersive spectrometry (EDS). The elastic properties, i.e., Young's, shear and bulk moduli and Poisson's ratio were determined from ultrasonic velocities and densities. The ultrasonic velocities were measured using a pulse-through transmission method; density was measured using a buoyant force method. These studies showed that: (1) these materials have amorphous structures; (2) these materials have Young's moduli of the order of 20 GPa, and (3) the silane couplant apparently did not significantly affect the elastic properties of these resin-based composites.
Electrochemical Charge and Protein Adsorption
Authors: Mueller Herbert J.
Published: March 2011

The amount of albumin adsorbed to three dental crown and bridge alloys (high- and low-gold content and silver-palladium), platinum, silver, and stainless steel was quantitated for the as-immersed conditions as well as with anodic and cathodic charge transfers in artifical saliva at a pH = 6.8. A methanolchloroform technique was utilized prior to protein assay which precipitated protein by phase separation. Amido black staining of protein on nitrocellulose filter paper was evaluated for optical density and compared to a standard curve of known quantities of protein. Cathodic charges decreased the quantity of adsorbed protein while anodic charges both increased and decreased adsorbed protein depending upon metal or alloy. Quantities adsorbed ranged from 0.5 to 8 μg/cm2. Interaction of positive oxidized species with the excess negative charges of the albumin molecules is thought to have increased protein adsorption. Formation of corrosion products with inorganic conponents is thought to have masked positive charges from protein thereby decreasing adsorption.
Phosphate Glass Dental/medical Cement
Authors: Chen Wei-Shi , Monroe E. A.
Published: March 2011

Current interest in the clinical application of alloplastic grafts for treating dental and orthopedic bone defects suggested this investigation on phosphate glasses. Particularly, the calcium phosphate ceramic materials of hydroxyapatite and tricalcium phosphate appear to be promising graft materials. Our interest in amorphous rather than crystalline ceramics centered on the potentially wide compositional variation that may be possible and their concomittant properties such as solubility.
Production of Highly Adherent Hydroxylapatite Coatings by Ion Beam and Plasma Techniques
Authors: Stevenson James R. , Solnick-Legg Hillary , Legg Keith O.
Published: March 2011

Starting with a pure hydroxylapatite sputter target, highly adherent coatings have been produced on metals and polymers by combining rf sputter deposition and ion implantation techniques. Reflection high energy electron diffraction (RHEED) scratch and adhesion tests have been done and more analysis is planned. Comparison of the RHEED data with HA and tricalcium phosphate standards shows the material to be polycrystalline hydroxylapatite rather than the amorphous, hydroxyl-free material usually produced by similar methods. Because of its structure this coating is expected to be nonresorbable. The coating is non-porous, hard and scratch-resistant. Data on the crystallography and mechanical properties of the coating will be presented.
Immunoadsorption and Absorptive Cell Separation
Authors: Yamazaki Z. , Kanai F. , Hiraishi M. , Idezuki Y. , Inoue N. , Tsuda N. , Katoh H. , Ide K. , Umegae M. , Ohno K.
Published: March 2011

As a means of selectively removing pathogenic macromolecular substances, an affinity adsorbent or immunoadsorbent has been investigated in experimental and clinical studies on blood purification in the treatment of immune diseases. There are several affinity adsorbents currently available for clinical application. The authors developed physicochemical affinity adsorbents Immusorba IM-TR and IM-PH, whose experimental and clinical evaluations have been satisfactory in several immune diseases, such as rheumatoid arthritis, myasthenia gravis, systemic lupus erythematosus and multiple sclerosis.

Absorptive cell separation, for leucocyte-free blood transfusion or for cytapheresis, has been developed using a leucocyte removal filter, whose container has fine, long fibers of polyester which are densely packed. The filters Sepacell and Cellsorba are used for erythrocyte transfusion and cytapheresis, respectively. In experimental and clinical trials, they provide efficient removal of leucocytes. Erythrocytes can be recovered virtually without loss. Clinical evaluation is now being conducted.

In conclusion, the above-mentioned new methods provide promising immunomodulations for the treatment and for the clearification of pathphysiology of immune diseases.
Effects of Nonspecific Cell/Surface Interactions on Cell Affinity Chromatographic Separations
Authors: Hammer Daniel A. , Lauffenburger Douglas A.
Published: March 2011

Exploitation of specific cell membrane receptor molecules is a promising avenue for the separation and purification of particular cell populations for biomedical and biotechnological purposes. Cell affinity chromatography is a technique which uses this principle to separate cells. In it, ligand molecules with a high binding affinity for specific receptors on targeted cell populations are immobilized on surfaces over which mixed cell populations are passed. These targeted populations are preferential retained, affecting a separation.

Often, the resulting separation is not as selective or efficient as the receptor/ligand biochemistry would promise. We present a theoretical analysis which elucidates the role of physical factors, such as van der Waals, electrostatic, and fluid mechanical forces, in affecting cell adhesiveness and hence selectivity. We demonstrate that only fairly narrow ranges of parameters characterizing these forces permit the selectivity inherent in the receptor/ligand biochemistry.
Measurement of Thromboembolism: Application to Patients with a Jarvik Total Artificial Heart
Authors: Adams George A. , Labow Brian , Carmody Ian , Hallee Christiane , Keon Wilbert J.
Published: March 2011

There have been in excess of 90 implantations of several different types of artificial heart (TAH) into patients. The bulk of these implantations have been using the Jarvik TAH as a bridge to provide interim circulatory support for the failed heart while a donor heart is being located and transported. Attempt to use the Jarvik TAH as a permanent, long-term heart substitute were complicated by hemorrhaging, sepsis, peripheral-organ failure and strokes [1]. These latter sequelae are thought to be due to thromboembolism and this concept is supported by the examination of explanted TAH from Barney Clark, the first recipient of the Jarvik TAH, which revealed large thrombus formation around the valve seats and microthrombi on the diaphragm that may have been the sites of thromboemboli [2]. In the case of bridges, the implantation periods are shorter, averaging 10 to 14 days but still a significant number of these patients have had thromboembolic events and explanted TAH have had microscopic aggregations of platelets and thrombi [3,4]. The response of blood to the constituent biomaterials of all cardiovascular devices is highly variable [5]. The documentation of thrombus on a biomaterial surface does not prove it will detach nor does the lack of thrombus on a surface indicate that the surface is benign, as thrombus could have formed and embolized. We have used two approaches to study the dynamic process of thrombogenesis and thromboembolism, in vivo and in vitro. Whole arterial blood samples were analyzed for thromboemboli as an in vivo assessment and epifluorescent videomicroscopy was used to monitor the mechanism of thrombosis, in vitro. Microparticles were found in the arterial circulation of patients with a Jarvik TAB and platelet thrombi were observed to form and embolize from Biomer-coated surfaces during perfusion.
Synthesis of Artificial Models of Sickle Red Cells
Authors: Macgregor Roderick D. , Taylor Noel , Lubin Bertram , Hunt C. Anthony
Published: March 2011

The primary role of a red cell substitute is to deliver oxygen to cells eitherin vivo or in vitro. It seems reasonable to mimic evolution, which solved the problem of oxygen delivery in many species by encapsulating oxygen carrying proteins in cell-sized delivery systems. We have successfully synthesized and tested an artificial red cell (Neohemocytes: see Science 230, 1165, 1985). How many properties or functions of red cells can one mimic synthetically? Can these synthetic cells serve as useful models? Here we report the first successful synthesis of an artificial model sickle cell. No reproducible, model cell system was previously available for research. A procedure identical to that used to prepare normal neohemocytes (NHC) was employed using sickle hemoglobin (HbS). The starting material was O2or CO liganded HbS at a concentration of approximately 15g% in a 30 mOsm phosphate buffer; this solution was kept ultrahypotonic until the final stage of the process. The lipid bilayer membrane was formed during a prolonged adjustment of the osmolality to 300 mOsm. The final step was removal of unencapsulated HbS. Sickle NHC were examined in parallel with normal (HbA containing) NHC by scanning and thin section electron microscopy before and after deoxygenation. These synthetic cells do sickle! Some look remarkably like red blood cells, only much smaller. Our data suggests that polymerization of the HbS within sickle NHC may be initiated by a different mechanism than the polymerization of purified solutions of HbS. The typical lipid bilayer seen in HbA containing NBC was essentially absent in the sickle NHC: similar results have been reported for irreversibly sickled red cells. Sickle NHC thus have remarkable potential to function as model sickle cells.
For1ation of Zeolites: A Molecular Description
Authors: Dutta Prabir K. , Puri M. , Shieh D. C.
Published: March 2011

Raman spectroscopy of the solution, solid and gel phases present during crystallization of zeolite X was investigated. The vibrational data indicate that an amorphous aluminosilicate solid, composed primarily of four membered aluminosilicate rings is in contact with monomeric silicate ions during the prenucleation stages of the zeolite formation. No intermediate building blocks specific to zeolite X could be discerned from the vibrational spectra. The influence of a series of monovalent cations on the crystallization process was also examined, and a model of zeolite formation has been proposed.
Cocation Effects in Rhodium-Exchanged Y Zeolites
Authors: Shoemaker R. K. , Johnson R. A. , Apple T. M.
Published: March 2011

Magic-angle spinning13C NMR spectra of carbon monoxide adsorbed on rhodium/Y zeolites yield information about the proportioning of CO in the various possible adsorption states; linear, bridged and dicarbonyl. The relative amounts of these adsorbed types, particularly the ratio of bridged to linear CO is influenced by the nature of the majority cations present with the rhodium. Reduced Rh-Na(+) and Rh-Li(+) zeolites form all three CO surface species, while acidic Rh zeolites, formed by the introduction of the co-cations Ca(2+) and H(+), exhibit no bridged carbonyls. The suppression of the bridged moiety results from the withdrawal of electrons from rhodium by the acid centers making the metal electron deficient (more oxidized).

Rh(I) dicarbonyl species form on all samples studied, however these species are indistinguishable from the linear monocarbonyls based solely upon the isotropic chemical shift obtained from magic-angle spinning. The number of dicarbonyl species can be quantitatively determined by the Carr- Purcell-Meiboom-Gill sequence, the powder pattern or by selective exchange experiments. At room temperature the two CO molecules in the gemdicarbonyl appear to undergo a mutual hopping exchange. This motion is frozen out at 198K. The carbon-carbon internuclear separation in the gemdicarbonyl is 3.3 Å.

Catalysts pre-adsorbed with13CO undergo exchange of the dicarbonyl species upon exposure at 198 K to12CO, however they also react to form13CO2. When exposed to CO at room temperature no CO2formation is detected.
Colloidal Routes to Catalysts: Pt-Au
Authors: Sermon Paul A. , Keryou K. , Thomas J. M. , Millward G. R.
Published: March 2011

A colloidal route to particles of Pt100-xAux of. high dispersion is reported; their activities and selectivities in hydrocarbon conversion are consistent with alloy catalysts prepared by other routes.
Structure-Sensitive Vibrations in Zeolites as Studied by Raman Scattering
Authors: Buckley R. G. , Deckman H. W. , Newsam J. M. , McHenry J. A. , Persans P. D. , Witzke H.
Published: March 2011

In this paper we demonstrate the usefulness of a nearest neighbor force model for studying the structural dependence of the lattice dynamics of zeolites. Interpreting Raman scattering in the context of this model confirms earlier empirical vibrational assignments in zeolites and underlines the importance of short range forces in determining the frequencies of certain zeolite vibrational modes. The model describes fully the low frequency bond bending mode of A1 symmetry, although long range forces are shown to be required to model complete zeolite vibrational spectra.
The Reactions of C2H2 and CH3C2H on Ag Powder
Authors: Dorain Paul B. , Boggio Joseph E.
Published: March 2011

Ag powder is activated by pulsing it with NO2 gas which forms fresh Ag microclusters. This powder is then exposed to subsequent pulses of C2H2 or CH3C2H (3.7% in N2 ). The surface enhanced Raman scattering (SERS) spectra show dramatic intensity variations due to rapid changes in adatom concentration. Normalization of these time-dependent SERS spectra to the background scattering intensity, which is proportional to the adatom concentration, provides spectra which represent adsorbate coverage if major surface reconstruction does not occur. The temporal development of the SERS spectra of C2H2 shows rapid degradation with no evidence for adsorbed species. In contrast, propyne reacts more slowly, as evidenced by the behavior of the intensity at 1980cm−1 due to adsorbed -C2-. The reactions observed are in accord with the models developed by Barteau and Madix[1] and Vohs, Carney, and Barteau[2]. Exposure to both alkynes results in the appearance of SERS active NO, an adsorbant not previously observed at room temperature. Ellipsometric measurements are consistent with the presence of a carbon overlayer, which may stabilize the NO and render the system inert to further chemical reaction.
Small-Angle X-Ray Scattering of Carbon-Supported Metal Catalysts
Authors: Goodtsman J , Phillips M. G. , Brumberger H.
Published: March 2011

The slit-smeared intensity of X-radiation scattered from carbon-supported metal catalysts behaves as clh−1 + c2h−3 for higher h-values in the small-angle region (h+4πλ−1 sinθ, λ + X-ray wavelength,θ + half of scattering angle, c1, c2 are constants). For three-phase systems with sharp phase boundaries, uniform electron-densities in the metal and void phases, and lamellar electrondensity fluctuations in the carbon phase, the small-angle X-ray scattering (SAXS) can be described in terms of inter- and intraphase electron-density correlation functions, and can be shown to yield the observed behavior. Further assumptions are required to separate these contributions and calculate interfacial specific surfaces. SAXS measurements on Pt, Ru, Pd, and Rh/C are presented.
Pillared Clays and Micas
Authors: Johnson Jack W. , Brody John F.
Published: March 2011

The interest in the petroleum industry in converting heavier feeds to liquid fuels has led to a search for microporous materials with pore sizes larger than those found in the faujasitic zeolites which form the basis of many petroleum processing catalysts. Materials with zeolite-like pores in the 10 Å range can be synthesized by intercalating large polyoxocations between the layers of smectite clays. Subsequent calcination dehydrates the cations and converts them into oxide pillars that prop the clay layers apart, resulting in permanent microporosity in the interlayer region. Pillared clays have been studied extensively during the last decade due to their potential use in petroleum processing as cracking and hydrocracking catalysts. Previous workers have primarily utilized smectite clays such as montmorillonite and hectorite as the starting layered material for pillared clay. We now report that synthetic fluoromicas, clay-like materials of layer charge density higher than that of smectites, can also be pillared with polyoxoaluminum cations to form aluminapillared fluoromicas that are thermally stable up to 700°C.
VPI-5: A Novel Large Pore Molecular Sieve
Authors: Davis Mark E. , Saldarriaga Carlos , Montes Consuelo , Garces Juan , Crowder Cyrus
Published: March 2011

This paper reports a novel family of aluminophosphate based molecular sieves denoted as VPI-5. These molecular sieves are the first to contain pores larger than 10 Å. The large pores of the VPI-5 sieves consist of long channels circumscribed by eighteen membered rings and are capable of adsorbing molecules excluded from other molecular sieves.
High Dispersion Metal Oxide/Molecular Sieves: New Bifunctional Shape Selective Catalysts
Authors: Szostak R. , Nair V. , Shieh D. C. , Thomas T. L.
Published: March 2011

Highly dispersed metal oxide/molecular sieve catalysts can be prepared through modification of metallosilicate molecular sieves. The resulting materials have been shown to exhibit enhanced catalytic activities for selected reactions. The metallosilicates examined include the gallosilicates, iron (ferri-) silicates and cobalt silicates. The size of the metal oxide particles as well as their location (in the pores or on the surface) can be controlled through post-synthesis methods. Thermal or mild hydrothermal treatment of the metallosilicate produces a highly dispersed metal oxide phase, while higher temperatures or longer treatment causes the metal oxide to migrate and form larger agglomerates of the metal oxide phase. The size of these agglomerates are strongly dependent on the conditions of hydrothermal treatment. Dispersion, location and agglomeration of the metal oxide phase have been characterized for the iron silicates using both physical and catalytic techniques. The magnetic properties of the iron silicates are described.
Theoretical Studies of Pt Chemisorption on γ Al2O3.
Authors: Low J. J. , Ellis D. E.
Published: March 2011

Generalized Valence Bond (GVB) and Local Density Functional (LDF) calculations were carried out to explore the influence of electronic structure on the metal-support interaction in Pt/γAl2O3. On the basis of GVB calculations it was found that ethylene can form either di-σ- or π complexes on Pt depending on the oxidation state of the metal. The LDF calculations showed that chemisorbed Pt transfers charge to γ-Al2O3. These results and experimental observations led us to propose a model of the metal-support interaction in which the Pt exists in two oxidation states for reduced Pt/ Al2O3 catalysts.
Structure and Reactivity of RH in the SMSI State
Authors: Braunschweig Ehrich J. , Logan A. David , Datye Abhaya K.
Published: March 2011

Hydrogenolysis of n-butane and CO hydrogenation were used to charac-terize the behavior of TiO2supported Rh in the SMSI state. The Rh was supported on a model support consisting of nonporous spherical particles of TiO2. The simple geometry of the support permits the metal crystallites to be imaged ‘edge-on’ in a transmission electron microscope. This allows detailed examination of the metal surface and the metal-oxide interface as a function of pretreatment. After high temperature reduction in H2, there is no significant change in the morphology of the Rh crystallites. However, the presence of amorphous overlayers 0.2–0.4 nm thick is clearly evident on the Rh surface. These overlayers can only be partially removed after oxidation at 473 K. The presence of these overlayers is well correlated with the drop in hydrogen chemisorption and altered reactivity. While the butane hydrogenolysis activity of Rh is considerably suppressed in the SMSI state, the CO hydrogenation activity is increased by a factor of 3. The H2uptake and the butane hydrogenolysis activity can be only partially restored after oxidation at 473 K. Treatment at 773 K in oxygen is necessary for restoring the pre-SMSI behavior.
Investigation of Novel Iron Oxide-Chromia on Alumina or Magnesia Aerogel Catalysts for the Selective Reduction of Nitric Oxide by Ammonia
Authors: Willey Ronald J. , Olmstead J. , Djuhadi V. , Teichner S. J.
Published: March 2011

A series of iron oxide-chromia on alumina and iron oxide on magnesia materials were made by the aerogel process. These materials had high surface areas (300 to 700 m2/g) and demonstrated good activity for the selective reduction of nitric oxide by ammonia.

A combination of 4 parts Fe to 1 Part Cr gave the best catalyst for the reaction. Fe-Cr to alumina ratios were varied from 0.1 to 0.4. Activity per unit weight increased with increasing Fe-Cr/A12O3ratios, however, activity per unit Fe-Cr favored the lower Fe-Cr to alumina ratios.

The fresh material from the autoclave was found reduced (Fe3O4) and initially had poor activity for the selective reduction of nitric oxide by ammonia (525 ppm NO & 525 ppm NH3in air feed conditions). However, after several testing cycles, in which the catalyst was in continuous contact with oxygen (as air), activity improved dramatically. Upon removal from the reactor the material had a distinct color change (from brown to reddish brown) and magnetic properties were lost. This suggests that Fe2O3is part of the active site for the selective reduction of nitric oxide by ammonia. At higher temperatures activity decreased because of a competing reaction, ammonia oxidation to nitric oxide.
51V NMR: A New Probe of Structure and Bonding in Catalysts
Authors: Eckert Hellmut , Wacjs Israel E.
Published: March 2011

Solid State 51V NMR spectra are sensitive to changes In the surface structure of V2O5 dispersed on Al2O3 and TiO2 supports. For V2O5 supported on alumina, wideline and magic-angle spinning experiments at 4.7 and 7.0 T reveal the presence of two vanadium species with different bonding environments. The relative proportions of these species change monotonically as a function of the vanadium concentration. In contrast, supported vanadium oxide on TiO2 substrates show a much more V2O5-like environment. Structural inferences are discussed In connection with solid state 51V NMR studies on model compounds with known crystal structures and site symmetries.
Mössbauer and Exafs Study of 57Fe Labelled Pt/SiO2 Catalysts
Authors: Sawicki J. A. , Rolston J. H. , Julian S. R. , Tyliszczak T. , McCrimmon K. D.
Published: March 2011

Specimens of highly dispersed Pt/Silicalite catalyst, decorated with 57Fe by impregnation in aqueous ferric nitrate solution, have been studied after decoration, and various pretreatments including exposure to carbon monoxide, by in situ Mössbauer spectroscopy. The form of Pt was followed by EXAFS analysis near the Pt LIII edge. The microstructural studies were combined with CO chemisorption and infrared absorption measurements. It is observed that iron in Pt clusters is very reactive even at ambient temperatures and that the interaction of Fe with CO is strongly accelerated by platinum.
Fixation of Cesium by Calcium Aluminosilicate Hydrates
Authors: Hoyle Susan L. , Grutzeck Michael W.
Published: March 2011

Recent work by the authors has demonstrated that cesium was being incorporated in a hydrated phase as their cement-based waste forms cured. The objective of the present study was to identify the hydrated phases responsible for the observed cesium incorporation. Four calcium aluminosilicate glasses having a 1:2 Al2O3/CaO ratio and a 25–70 mole % silica content were mixed with ˜0.3 molar CsOH or CsCl solutions (water/solid ratio = 10) and allowed to hydrate at 38° and 90°C for periods up to 90 days. Paste equivalent samples, having a water/solid ratio of 1.0 were also prepared to gauge the cementing properties of these mixtures. Solutions were analyzed for Ca, Al, Si, and Cs while solids were characterized using x-ray powder diffraction and scanning electron microscopy.

Glasses exposed to the CsOH solution were more reactive than their counterparts exposed to the CsCl solution. In addition, reactivity as well as crystallinity seemed to be higher at 90° than at 38°C. At least two cesium-containing zeolites were identified in the 90°C CsOH solution experiment: A cesium-containing wairarkite analogue and possibly another cesium-containing zeolite unidentified at this time. The relatively complete removal of cesium from the solution, in one case, as well as the fact that the mixtures are self-cementing suggests that the glasses may be “engineered” to serve as overpack material in a deep-seated geologic repository.
Diffusion in the Matrix of Granitic Rock Field Test in the Stripa Mine
Authors: Birgersson Lars , Neretnieks Ivars
Published: March 2011

Three similar migration experiments in the matrix of granitic rock are presented. The experiments have been carried out in “undisturbed” rock, that is rock under its natural stress environment. Since the experiments were performed at the 360 m level (in the Stripa Mine), the rock was subjected to nearly the same conditions as the rock surrounding a nuclear waste repository as proposed in the Swedish concept (SKB).

A mixture of three non-sorbing (conservative) tracers, Uranine, Cr-EDTA and I−, were injected into the granitic rock matrix for time periods of months up to years. The subsequent overcorings of the injection holes showed that the tracers had in some cases migrated at least ≈ 400 mm (measuring limit) into the rock matrix for the experiment with the longest injection time. It could also be seen that there were large differences in migration distance into the rock matrix for samples taken fairly close to each other. One example where the tracers have diffused through fissure coating (filling) material located in “undisturbed” rock is also presented.

The results from all three experiments show that all three tracers have migrated through the disturbed zone close to the injection hole, through the fissure coating material and a distance into the “undisturbed” rock matrix.

These results therefore indicate that dissolved compounds may migrate into the rock matrix. This migration into the rock matrix will increase the area available for sorption of radionuclides significantly and may therefore increase the migration times for radionuclides by order(s) of magnitude.

Diffusivities and hydraulic conductivities obtained in this in-situ experiment compare well with those obtained in laboratory experiments.
3–-D Migration Experiment in Sparsely Fractured Crystalline Rock
Authors: Abelin Harald , Birgersson Lars , Gidlund Jard , Moreno Luis , Ågren Thomas , Widén Hans , Neretnieks Iivrs
Published: March 2011

A large scale tracer experiment has been performed in sparsely fractured granitic rock at 360 m depth. Nine different conservative tracers were injected at distances ranging between 10 and 56 m from a drift excavated for this experiment. The upper part of the test site was covered completely with plastic sheets. All the water entering into the drift could be collected. Water flow monitoring shows that water flow takes place in small areas with large dry areas in between. Of the nine injected tracers six reached the test site during the experiment. The fitting of the breakthrough curves to different models could not satisfactorily explain the actual processes involved in the tracer migration. The results of the tracer experiments and the Tritium measurements gave strong support to the notion that a non–negligible portion of the flow takes place in more or less isolated channels.
Sensitivity Surfaces for the Assessment of Waste Package Performance
Authors: Leneveu D. M. , Garisto N. C.
Published: March 2011

Sensitivity surfaces have been developed to analyse the performance of engineered barriers of an underground nuclear fuel waste disposal vault. The major engineered barriers are the waste form, the containers and the buffer surrounding the containers. A modular computer code has been developed that calculates the release rate from each barrier. The modules are linked together through the use of time-series-management routines. By systematic variation of the model input parameters, sensitivity surfaces are constructed that illustrate the behaviour of an objective function such as maximum fractional release rate in response to the changes in the input parameters.
Validation of a Nuclear Waste Repository Performance Assessment Model:Comparison of Theory With Experiment
Authors: Geldart R. W. , Mcgrail B. P. , Rhoads K. C. , Apted M. J.
Published: March 2011

Laboratory tests were conducted to validate a radionuclide mass transfer model. During the experiments, cesium and uranium releases from a simulated waste form embedded in an isotropic medium of quartz sand were measured. A 0.01 M NaH2PO4 buffer solution flowed past the waste form. Downstream concentrations obtained from computer simulations were compared with experimentally measured concentrations of cesium and uranium. Uranium release was found to be controlled by solubility-limited mass transfer, while cesium release was controlled by waste form dissolution kinetics. It was also found that the effects of dissolution on groundwater chemistry must be coupled with solubility-limited mass transfer models to defensibly predict radionuclide release rates under realistic repository conditions.
Application And Results Of A Reinjection Technique For Hydrothermal Experiments In Dickson Autoclaves
Authors: Gardiner M. A. , Kacandes G. H. , Ulmer G. C. , Grandstaff D. E.
Published: March 2011

Cohassett basalt was reacted with synthetic Hanford groundwater in a Dickson rocking autoclave at 300°C and 30 MPa for ca. 7600 hours. During the experiment fresh solution was twice reinjected into the reaction cell, raising the nominal water:rock mass ratio from 50:1 to 140:1. The reinjection experiment is intermediate between closed-system Dickson experiments and flow-through tests in that the fluid and solids can remain in contact for extended periods of time before the solution is replaced. This allows more time for equilibrium to be approached. Data from this experiment suggest:

(1) After reinjection many solution parameters quickly (hrs-days) returned to near preinjection values. (2) The redox buffer capacity of the basalt was not exceeded, i.e. fO2 values remained near magnetite-hematite values, although the nominal water:rock mass ratio was raised to ca. 140 during the experiment. (3) After reinjection the stable high-temperature pH value was only slightly less than the initial pH value. (4) The silica concentration stabilized near apparent quartz saturation rather than the cristobalite saturation value found in closed-system experiments. (5) Short-term relationships between cations appear to be controlled by ionexchange between the solutions and clay minerals.

Reaction products identified from the experiment include: Fesmectite, illite, hematite, minor cristobalite and possibly Ti-maghemite.
Experimental Interaction of Basalt, Bentonite, and Water: Implications for Groundwater Chemistry in Waste Package Packing Material in a Nuclear Waste Repository
Authors: McKeon Gail L. , Thornton E. C. , Halko D. J. , Wood M. I.
Published: March 2011

Experiments have been conducted by the Basalt Waste Isolation Project (BWIP) to assess changes in solution chemistry in the near-field environment of a nuclear waste repository in basalt. These Dickson autoclave experiments were carried out using Grande Ronde basalt ± bentonite and synthetic groundwater or deionized water at 300°C, 30 MPa, and solution-to-solid mass ratio of 10 for up to two years. Groundwater solution changes during reaction of the basalt and basalt/bentonite included initial decreases in pH and sodium concentration presumably due to smectite formation. This initial trend subsequently reversed in the basalt system with pH rising to ca. 7.5 and sodium increasing to the starting value. Steady state pH values for the basalt/bentonite system were ca. 6.4. The basalt + deionized water test exhibited a constant rise in pH to ca. 7.9 and release of sodium to solution in response to basalt dissolution. Slightly oxidizing conditions characterized the early part of all of the experiments followed by a decrease in fO2 to 10−31 to 10−32 These results are consistent with other work at similar and lower temperatures, suggesting that the packing material will react in the waste package environment to produce slightly alkaline, reducing conditions.
Spent UO2 Fuel Corrosion in Water; Release Mechanisms
Authors: Werme Lars O. , Forsyth Roy S.
Published: March 2011

An update of the status of the joint SKB/Studsvik fuel leaching programme is given. High burnup BWR fuel has been leached for up to 5.5 years cumulated contact time. Data for leaching of PWR fuel are also presented. The present results confirm earlier results from the programme, i.e., in groundwater and deionized water under oxidizing conditions uranium rapidly attains saturation at about 1 mg/l and 10 μg/l, respectively.

Under reducing conditions, the uranium saturation levels are below 1μg/l. The plutonium saturation level under oxidizing conditions is at about 0.3 μg/l. Under reducing conditions, the plutonium concentrations in solution appear to be controlled by the solubility of the fuel matrix.

Most of the detected fission products appear to be released through selective leaching of fuel/cladding gap, fuel cracks and fissures, and grain boundaries.
Radionuclide Release Behavior of Light Water Reactor Spent Fuel Under Hydrothermal Conditions
Authors: Neal William L. , Rawson Shirley A. , Murphy William M.
Published: March 2011

The Basalt Waste Isolation Project has performed initial characterization of the release behavior of radionuclides from ATM-101 spent fuel reacted under hydrothermal conditions. Results to date indicate that 1) 14C, 90Sr, 129I, and 137Cs exhibit preferential release to solution relative to the actinides, 2) 239+240Pu, 241Am, and 244Cm ratios in solution are consistent with stoichiometric dissolution of the spent fuel matrix, whereas uranium concentrations are higher than those predicted for stoichiometric dissolution, 3) 137Cs release varies as a function of the fluid to solid mass ratio, and 4) 14C, 129I, and 137Cs release is affected by fuel particle size and/or fuel washing.
Analytical Electron Microscopy of Leached Layers on Synthetic Basalt Glass
Authors: Murakami T. , Ewing R. C. , Bunker B. C.
Published: March 2011

Analytical electron microscopy was used to characterize leached layers formed on a synthetic basalt glass after 300 days in deionized water, sodium chloride solutions, or sodium chloride solutions containing magnesium chloride. Ultramicrotomed cross-sections show that the leached layers consist of a mixture of amorphous and crystalline phases whose composition and microstructure are sensitive to solution chemistry. In general, Na, Ca and Mg are selectively leached in all solutions, leaving behind surface alteration products which are rich in Fe, Ti, and Al. In deionized water and the NaCl solution, gibbsite (AI(OH)3) is a major phase; in the Mg-containing solution, Si and Al are retained as smectite clays. Results are compared to the alteration of natural basalt glasses in marine environments, particularly as they relate to the use of basalt glass alteration as a means of verifying the long-term leaching behavior of nuclear waste form borosilicate glasses.
Mass Transfer from Penetrations in Waste Containers
Authors: Pescatore C. , Sastre C.
Published: March 2011

Recent studies have indicated that localized corrosion of a relatively small area of a waste container may impair the containment function to such an extent that larger releases may be possible than from the bare waste form. This would take place when a large number of holes coexist on the container while their concentration fields do not interact significantly with each other. After performing a steady state analysis of the release from a hole, it is shown that much fewer independent holes can coexist on a container surface than previously estimated. The calculated radionuclide release from multiple independent holes must be changed accordingly. Previous analyses did not proceed to a correct application of the linear superposition principle. This resulted in unacceptable physical conclusions and undue strain on the performance assessment necessary for a container licensing procedure. The paper also analyzes the steady state release from penetrations of finite length and whose concentration fields interact with one another. The predicted release from these penetrations is lower than the previously calculated release from holes of zero thickness. It is concluded here that the steady-state release from multiple holes on a waste container can not exceed the release from the bare waste form and that multiple perforations need not be a serious liability to container performance.
Predicting the Long Term Corrosion of Metal Containers for Nuclear Waste Disposal
Authors: Marsh G. P.
Published: March 2011

The prediction of the long term corrosion of metal containers for nuclear waste under geological disposal conditions requires the extrapolation of corrosion data over several hundred years. There is a general trend to use either simulation or ‘worst case’ experiments as a means of materials selection, but neither really addresses the problem of long term extrapolation. It is proposed that such an extrapolation can only be done convincingly if it is based on a sound and generally accepted mechanistic understanding of the processes involved. If such knowledge does not exist the first step must be to acquire it through experimental mechanistic studies. Subsequently such knowledge should be formulated into mathematical models, which can be used to make long term predictions, and which can be validated by comparison with short term experimental results. The application of this combined mathematical modelling/experimental approach is illustrated for three corrosion processes which may affect carbon steel containers, namely general corrosion, localised attack and stress corrosion cracking.
Spent Fuel: Characterization Studies and Dissolution Behaviourunder Disposal Conditions
Authors: Johnson L. H. , Shoesmith D. W. , Stroes-Gascoyne S.
Published: March 2011

The concept of disposal of unreprocessed spent fuel has now been under study internationally for over ten years. Considerable progress has been made in understanding the factors that will control radionuclide release from spent fuel in an underground disposal vault. This progress is reviewed and the research areas of significance in providing further data for source term models are discussed. Key areas for future research are identified; these include improved characterization of spent fuel to determine the inventories of fission products at grain boundaries, together with their release kinetics; and a better understanding of the effects of solution chemistry on spent fuel dissolution, in particular the effects of salinity, redox chemistry, and radiolysis of groundwater. Approaches to modelling the dissolution of spent fuel are discussed, and a possible approach for developing an oxidative dissolution model is outlined.
Electron Microscopical Studies of Tricalcium Silicate - Fly Ash Blended Pastes
Authors: Rodger S. A. , Groves G. W.
Published: March 2011

Fly ash (FA) is becoming a common addition to ordinary portland cement (OPC) both in Europe and in the USA. Although a great deal of work has been carried out to characterize fly ashes from different sources, less work has been reported in the literature as to the exact nature of the reaction products when fly ash blends are hydrated. Microstructural studies carried out using scanning electron microscopy (SEM) of fracture surfaces have been summarized by Diamond [1]. The results often show a shell of reaction product around the fly ash residues. Some authors have postulated the formation of a duplex film of calcium hydroxide (CH) and calcium silicate hydrate (C-S-H) around the particles. However SEM alone cannot reveal the composition of features in the microstructure and interpretation on the basis of the morphology of the features may be misleading. Some analytical electron microscopy has been carried out using crushed particles of blended pastes [2] but this technique results in a loss of information about the location of analyzed areas.
Sulfate-Resistant Portland Cement from Lime-Soda Sinter Process Residue
Authors: Chesley J. A. , Burnet G.
Published: March 2011

A by-product (residue) from the Ames Lime-Soda Sinter Process for recovering alumina from power plant fly ash consists largely of dicalcium silicate and can be used as a raw material for the manufacture of sulfate-resistant (Type V) portland cement. Utilization of the residue will eliminate the need for its disposal and will improve the economic feasibility of the lime-soda sinter process. Laboratory burnability tests were used to identify optimum cement mixes and burning temperatures from both clinker quality and economic perspectives. At a typical kiln temperature of 1450°C, cements that formed concrete that exceeded ASTM specifications for strength were obtained for a limited range of lime-saturation factors and silica ratios. A highly conservative cost estimate for a combined alumina recovery and cement manufacturing facility for a 1000 MWe coal-fired power station gave a 4.7% internal rate of return.