bluuebunny/crossref_metadata_2025 huggingface dataset:
”Nonlinear Optical Materials & DoD Device Requirements”
Authors: Kushner Brian G. , Neff John A
Published: March 2011

Within the past several years, the development of advanced materials with large second and third order nonlinear (X2 and X3) effects has generated interest in developing devices to exploit these properties in military systems of the future. This interest has taken many forms, from the funding of basic research aimed at developing enhanced nonlinear optical effects in materials to the deployment of actual mil-spec devices. Two years ago, at this same forum, we delineated a series of materials performance requirements which, if achieved, would allow device developers to take maximum advantage of these nonlinear effects in such disciplines as optical computing, optoelectronic interconnects and sensor protection. In the interim, DoD requirements for advanced materials and devices have continued to accentuate the need for advanced nonlinear optical materials. This paper will discuss some of the most recent trends in nonlinear optical materials research from a device requirements perspective, including an overview of the results of the recent DARPA forum on nonlinear optical materials and a discussion of future directions. As in the previous paper, we will confine ourselves to three challenging areas: nonlinear optical materials for optical computing applications, materials for computer peripherals and internode communications, and materials for sensor protection.
Optically Nonlinear Films of Amphiphilic Polymers: Synthesis, Langmuir-Blodgett Deposition, and Optical Measurements
Authors: Hall Robert C. , Lindsay Geoffrey A. , Anderson Brian , Kowel Tephen T. , Higgins Brian G. , Stroeve Pieter
Published: March 2011

Novel polymers are synthesized by attaching amphiphilic dye groups along a hydrophilic polyether backbone. These polymers are fabricated into noncentrosymmetric films by the Langmuir-Blodgett (L/B) technique. Stacks of molecular bi-layers are assembled by γ-type deposition, interleaving two different dye-substituted polymers. One polymer has the dye's molecular dipole pointing toward the backbone, while in the other polymer, the dye points in the opposite direction. Light from a Nd:YAG laser is passed through these films and the second harmonic is detected.
New Method for the Measurement of Electro-optic Constant of Polycarbonate Films Doped with 4-Diethylamino-4′-Nitrostilbene Molecules
Authors: Uchiki Hisao , Kobayashi Takayoshi
Published: March 2011

We propose a new method for the determination of the electro-optic constant. Third-order nonlinear susceptibility (X(3)(-ω;ω,0, 0)) of polycarbonate films doped with 4-diethylamino-4′-nitrostilbene molecules was determined between 550 and 800 nm at room temperature by using this method. X(3)(-ω;ω0, 0) is (5-4i) × 10-12 esu at 600 nm.
Highly Oriented Unsubstituted Polydiacetylene
Authors: Jorgensen B. , Aldissi M. , Liepins R. , Agnew S.
Published: March 2011

Highly oriented, unsubstituted polydiacetylene was obtained by the polymerization of 1,3-butadiyne in perhydrotriphenylene (PHTP). The canal structure of PHTP induces a high degree of order in the polymer. Transparent orange crystals were formed which were shown by SEM to consist of structures oriented parallel to the long axis of the crystal. Resonance Raman and UV-visible spectroscopy indicate the polymer consists of seven to ten conjugated ene-yne type repeat units. Crystallization of the inclusion complex was induced inside glass capillaries so the crystals filled the entire space along the length of the capillary.
Nonlinear Optical Polymers for Electrooptical Devices
Authors: DeMartino R. , Haas D. , Khanarian G. , Leslie T. , Man H. T. , Riggs J. , Sansone M. , Stamatoff J. , Teng C. , Yoon H.
Published: March 2011

Although organic crystals may be used to experimentally verify the large nonlinearities and short response times of organics, such crystals are not acceptable for device applications due to significant fabrication difficulties. Further, the bulk material nonlinearity is a function of molecular orientation and symmetry which may not be controlled during the crystallization process.

Nonlinear optical polymers have been synthesized at Hoechst Celanese for which the active NLO unit is attached to the polymer backbone as a pendant side chain. Control of orientation and symmetry of the unit is achieved by poling in an external electric field at elevated temperatures resulting in second order susceptibilities larger than inorganic crystals. The polymers have attractive secondary properties (i.e., optical transparency, high glass transition temperatures which are controlled by adjusting the side chain length and nature of the polymer backbone, low dielectric constants, and flat frequency respose). Further, single mode waveguides may be fabricated by spin coating. Deposition of electrodes on the waveguide permits application of an external field which changes the material's index of refraction due to the linear electrooptical effect. Thus, a host of electrooptical waveguide devices may be constructed which operate at low voltages and very high frequencies.
Effect of a Moderate Blood Exchange with Fluosol-Da 20% on the Disposition of Digoxin in the Dog
Authors: Hoke John F. , Ravis William R.
Published: March 2011

The effect of a perfluorochemical blood substitute (Fluosol-DA 20%) on the disposition kinetics of digoxin in the dog was studied. An intravenous dose of digoxin was administered at either 0.25 or 24 hours following a 30% blood exchange with the dog's own blood (SHAM group) or Fluosol-DA (treatment group). A significant change in the initial volume of distribution and mean residence time in the serum was noted when digoxin was administered 0.25 hours after the Fluosol-DA blood exchange. This volume of distribution change was not observed when digoxin was administered 24 hours after the Fluosol-DA blood exchange. No change in the t1/2, total body clearance, or volume of distribution at steady-state was observed in any of the treatments. No change in the partitioning of digoxin in the blood was noted following Fluosol-DA administration.
A Perspective on the FDA Premarket Approval Process
Authors: Ely John L.
Published: March 2011

Premarket review processes as prescribed by the Medical Device Amendments of 1976 to the Food, Drug, and Cosmetic Act greatly affect the use of materials in medical products, especially for implantable devices. The premarket approval process can have a particularly important role in eventual commercial medical uses of materials. Managing the process properly is often critical to the success or failure of a product.

A review of the law and regulations as they pertain to premarket approval is presented. Subjects included in this overview are prediction of process time and costs, examination of potential pitfalls in the process, recommendations on organizing for successful completion of the process and handling the relationship with FDA.

Specific materials related issues that are likely to arise are noted.
Dental Materials and Technology Research at the National Bureau of Standards, a Model for Government-Private Sector Cooperation
Authors: Tesk John A.
Published: March 2011

Cooperation is one avenue being pursued among American industry, labor, and government to ensure a strong internationally competitive U.S. economy. At the National Bureau of Standards (NBS), we have a program which facilitates cooperative interaction. This article focusses on one of our longest running cooperative projects, dental materials research.
Development of a Resorbable Tricalcium Phosphate (TCP) Amine Antibiotic Composite
Authors: Morris Lisa M. , Bajpai Praphyilla K.
Published: March 2011

Calcium phosphate collagen composites are currently being used to rebuild bone. Commercial collagen preparations have been claimed to he hvpo-antigenic but none are non-antigenic. The collagen in calcium phosphate collagen composites is eventually degraded to its component amino acids. Two thirds of collagen consists of glvcine, hvdroxvproline, and proline. Since both tricalcium phosphate (TCP) and collagen are resorbable and both can he utilized to form bone, incorporation of amino acids into TCP-amino acid composites should nrovide the building blocks for formation of new bone. Stich composites should also be non-antigenic. Previous work conducted with composites of amino acids with aluminum calcium phosphorous oxide (ALCAP) ceramics, has shown that these composites can be uised to repair traumatized bone in rats. In our study, experiments conducted with TCP cysteine, Ivsine, or proline composites showed that the composites, after setting to hardness, degrade slowly and can he molded into different froms. Dissolution studies were conducted with composites of TCP with each of the above amino acids in Tris-MCl buffer (PH 7.4) at 37°C in vitro. Experiments conducted with antibiotics showed that antibiotics such as penicillin and ervthromvcin can be incorporated into the TCP amino acid composite. Subcutaneous implants of TCP amino acid composites in rats showed that most of the TCP-proline composite was degraded bv day 4, TCP-lvsine composite he day 7, and TCP-cysteine composite by day 21. Our results suggest that TCP amino acid composites are biocomnatible and can he used to repair experimentally traumatized bone.
Demonstration of the Bacterial-Biomaterial Interface in Implant Specimens
Authors: Dobbins J. J. , Giammara B. L. , Hanker J. S. , Yates P. E. , DeVries W. C.
Published: March 2011

Bacterial infection can be a problem associated with biomaterial implants especially with the total artificial heart or other cardiovascular prostheses such as ventricular assist devices, intravenous catheters, ventriculo-atrial shunts, pacemaker electrodes and, rarely, prosthetic heart valves. Bacterial commensals such as Staphylococcus epidermidis, which is ordinarily non-infective in human skin and mucous membranes, is now recognized as an opportunistic pathogen of biomaterial implants, particularly cardiovascular prostheses. In these implantations the S. epidermidis undergoes transformation to produce mucoid or polysaccharide extracellular coating substances. The latter promote bacterial adherence to biomaterial surfaces and protect the bacteria to some extent against antibiotics and host defense mechanisms. The result is increased virulence of the slime-producing strains. A number of techniques have been developed in our laboratories which facilitate identification of such bacterial pathogens on biopsy or postmortem specimens. These light and analytical electron microscopic methodologies include special cytochemical staining and rapid drying and embedding methods. Their efficacy and accuracy have been verified by studies on cultured and subcultured pathogens which are more time consuming. It is of interest that the microscopic methods showed the presence of macrophages as well as neutrophils on the specimens.
Analytical and Structural Electron Microscopy of Metal-Cell Interactions.
Authors: Coombs Neil A. , Pilliar Robert M. , Weatherly George C.
Published: March 2011

Human gingival fibroblasts have been grown in culture on thin (10–50nm) substrates of nickel, chromium and titanium and examined by structural and analytical transmission electron microscopy. Cells grown on titanium show no signs of metal uptake and have morphologies very similar to controls grown on carbon substrates. However, cells grown on nickel and chromium show significant metal uptake and some structural abnormalities. The majority of the ingested nickel and chromium appears to be associated with nucleic acids.
Low Voltage Sen for Unique Surface Analysis of Prosthetic Devices
Authors: Goldberg Eugene P. , Yalon Moshe , Longo William E.
Published: March 2011

Surgical manipulation of plastic prostheses using metal instruments is likely to produce surface damage and surface roughness which may compromise biocompatibility of implants due to tissue irritation and increased cellular or bacterial adhesion. There are virtually no data in the literature concerning the clinical occurrence and consequences of manipulative surface damage to implants. We have found that conventional high voltage scanning electron microscopy techniques (HVSEM) obscure surface defects on plastics due in large measure to beam energy “healing” by local melting. This paper reports the use of low voltage SEM (LVSEN) at low beam voltages (<1.5keV) and without the need for conductive carbon or Au/Pd coatings for examination of plastic device surfaces before and after normal surgical manipulation. Results for intraocular lens implants, a major human prosthesis, clearly demonstrate that standard surgical procedures can produce significant implant surface damage which may not be observed by normal SEN analysis. LVSEN has been shown to readily visualize such previously unobserved surface defects in model surgical manipulation experiments. These results have important implications for more reliable polymer surface characterization and for development of improved prosthetic devices, instruments, and implant surgery.
Cryopreserved Dermis is an Ideal Substrate for the Engraftment and Maturation of Human Epidermal Keratinocyte Cultures
Authors: Langdon Robert C. , Cuono Charles B. , Birchall Nicholas , Moellmann Gisela E. , Madri Joseph A. , McGuire Joseph
Published: March 2011

The ideal replacement for skin damaged by full-thickness injury is the split-thickness autograft. In extensive burns, use of autograft is limited by the availability of uninjured donor skin. This limitation can be overcome by grafting viable cryopreserved cadaveric skin following escharectomy. To preclude immunologic rejection of the allograft, the epidermis is later removed by abrasion and replaced with autologous keratinocyte cultures. The cultures rapidly stratify and within 7 days form a differentiated epidermis of normal thickness. Over several weeks the basement membrane zone reconstitutes normally by several criteria including the presence of a lamina densa and of anchoring fibrils and immunohistochemical demonstration of type IV collagen and laminin. Melanocytes, which are present in small numbers in the keratinocyte cultures. assume their normal position and function in the epidermis of the composite graft. Langerhans cells migrate into the autologous cultured keratinocyte graft.

Autologous keratinocytes can be greatly expanded in cell culture and used as grafts to resurface large areas. The functional quality of such grafts however is dependent on the ability of the dermal substrate to support the permanent engraftment of keratinocyte cultures through reconstitution of a normal basement membrane zone.
Collagenous Materials Enhance Healing of Chronic Skin Ulcers
Authors: Silver Frederick H. , Doillon Charles J. , Rojo Blas , Olson Robert M. , Kamath Chandrakala Y. , Berg Richard A.
Published: March 2011

Type I collagen in a porous sponge form attracts fibroblasts in culture and accelerates repair of animal wounds. This study examines the effect of type I collagen sponge and flakes on healing of chronic skin ulcers. Patients included in this study had skin ulcers.

Patients included in this study had skin ulcers characterized by loss of dermis and epidermis without exposure of muscle, tendon or bone. Patients showing evidence of systemic infection or patients with ulcers that decreased in area during an initial three week observation period were excluded.

Three out of seven patients treated with a collagen sponge and twelve out of fourteen patients treated with collagen flakes showed a 40% decrease in wound area after six weeks of treatment. In comparison, eighteen control patients showed no change in wound area over the same time interval. These results suggest that collagen flakes are effective in initiating healing of chronic skin ulcers.
Polymers as Ophthalmic Lubricating Agents
Authors: Kalachandra S. , Shah D. O.
Published: March 2011

Physio-chemical properties such as coefficients of friction between low energy surfaces (PMMA/PMMA), surface tension, contact angle and viscosity of various water soluble polymer solutions ( 3–62cp) were measured at ambient temperature. The results showed that the surface tension and the contact angle are independent of viscosity of each polymer. The analysis of the data revealed that the system is operating in a region of “Boundary Lubrication”. It is seen, beyond 30 cp viscosity of almost all polymer solutions, the coefficient friction has been found to be independent of viscosity.

Polyvinyl alcohol appears to have better lubricity in the vicinity of 30 cp viscosity or lower values than the cellulose derivatives and dextran. Hydrophobic interaction between PMMA surface and vinyl backbone may be responsible for this observation.

It appears that the coefficient of friction of these polymer solutions depends on the structure, conformation and adsorption characteristics of polymers as well as surface characteristics of sliding surfaces, load, speed and viscosity.
The Elastic Properties of Osteoporotic and Osteopetrotic Bone
Authors: Katz J. Lawrence , Yoon H. S. , Meunier A. , Christel P.
Published: March 2011

We have been involved in using several ultrasonic wave propagation techniques to study the relationship between the structure and the elastic properties of bone, both normal and pathological. Pulse through ultrasonic techniques have been used to measure the ultrasonic velocities in human, normal, osteoporotic and osteopetrotic femoral bones in vitro at 5 MHz and room temperature. An ultrasonic right-angle reflector technique has also been used on the same specimens at room temperature and 15 MHz (the third harmonic of a 5 MHz immersion type transducer). In addition, microhardness measurements have been made on the same bones from which the specimens for ultrasonic measurements were obtained.
The Influence of Biomechanical Factors at the Tissue-Biomaterial Interface
Authors: Brunski John B. , Hipp J. A. , Cochran G. V. B.
Published: March 2011

When an implant is placed into bone, an interface is created. This interface has a critical biomechanical function: it must support the implant in bone. However, failure of implant fixation (i.e., implant “loosening”), continues to be a leading cause of implant failure [1,2]. While there are a number of factors involved in this problem, it is recognized that biomechanical factors play a role, and this paper reviews the more important factors, including relative motion and interfacial stresses and strains. Also, it presents results from a recent in vivo experiment on controlled loading of an interface.
Ion Beam Deposition of Calcium Hydroxyapatite
Authors: Barthell B. L. , Archuleta T. A. , Kossowsky Ram
Published: March 2011

Calcium hydroxyapatite has been sputtered on glass and Ti-6Al-4V substrates using a 1.5-kV argon ion beam. The films have been examined by x-ray diffraction analysis, energy dispersive spectroscopy, scanning electron microscopy, and adhesion testing. Results of this experimentation are presented.
Glycocalyx Enhances Prosthetic Vascular Graft Infection
Authors: Evers B. Mark , Giammara Beverly L. , Jubenville Denise , Malangoni Mark A.
Published: March 2011

Coagulase-negative staphylococci are major pathogens in prosthetic implant infections, and the capability of certain strains to produce glycocalyx enhances their infectivity. We investigated the importance of glycocalyx in an animal model of prosthetic vascular graft infection. Coagulasenegative staphylococci (5×108) and 1 cm2pieces of Dacron or polytetrafluoroethylene (PTFE) grafts were placed in subcutaneous pockets of adult Sprague-Dawley rats. Two strains of bacteria were used, one producing and the other not producing glycocalyx. At 5 days, uninfected grafts were incorporated into the surrounding tissues whereas infected grafts were surrounded by fluid. Grafts were excised and adherent bacteria dislodged by sonication and quantitated. Scanning electron microscopy confirmed the presence of bacteria and glycocalyx, and the efficiency of bacterial dislodgement by sonication. The bacterial adherence (CFU/cm2mean ± SE) of glycocalyx-producing staphylococci was 3.7±1.1×107and 3.5±1.0×105to Dacron and PTFE, respectively (both < 0.05). Nonglycocalyx producing bacteria had decreased adherence to both Dacron (1.4±0.8×104) and PTFE (0.9±0.4±104). Antibiotic administration reduced the adherence of the nonglycocalyx producing strain by one log to both materials (p<0.05) but did not affect the glycocalyx-producing strain. These data demonstrate that glycocalyx production enhances the adherence of coagulase-negative staphylococci to prosthetic vascular graft materials. Prophylactic antibiotic administration does little to inhibit the adherence of glycocalyxproducing bacteria but does affect nonglycocalyx producing strains.
A Study of the Mass Transport Resistance of Glucose Across Rat Capsular Membranes
Authors: Freeman C. L. , Mayhan K. G. , Picha G. J. , Colton C. K.
Published: March 2011

The interaction between a polymer or other foreign surface and soft tissue is determined by a variety of materials and tissue factors. After failing to engulf the foreign body, the classical response is to wall it off. First the site is invaded by macrophages and giant cells and then fibrous connective tissue is laid down. This fibrous connective tissue gradually replaces the cellular matrix and forms the capsule. The composition is mostly collagen and mucopolysaccharides with few cells in the mature capsule. It contains 75–80% water.

When the implant surface represents a sensor and the transport of low molecular weight species across the capsule is necessary for meaningful measurement and response time, the mass transport resistance of the capsule may become a critical factor. This study represents an initial attempt to characterize the diffusion of glucose through fibrous capsules grown around silicone elastomer implants in a rat. Specifically, the study was designed to develop techniques to measure mass transport properties of tissue capsules, to use these techniques to determine effective glucose transport properties at two weeks, four weeks, and ten weeks after implant; and, to use these results along with histological examinations to gain an understanding of the factors which influence mass transport.
On the Propagation of Twin-Fault-Induced Stress in Platelet Fau-Framework Zeolites
Authors: Treacy M. M. J. , Newsam J. M. , Vaughan D. E. W. , Beyerlein R. A. , Rice S. B. , De Gruyter C. B.
Published: March 2011

A model describing the propagation of a rhombohedral distortion in platelet CSZ–1 zeolites is presented. It is proposed that internal stress gradients grown into CSZ–1 platelets at synthesis are responsible for this distortion of the cubic FAU framework, where the spacings of 111 planes parallel to the platelet surfaces are elongated relative to the {111} planes. The presence of inhomogeneities is suggested by the presence of thin bands of twin faults which are invariably observed near the central layers of each platelet. Elastic modelling confirms that the effects of any stress associated with such twin faults will be most pronounced in the thinnest platelets, where the effects of elastic relaxation are minimal, and where the width of the fault zone relative to the platelet thickness is maximal. Platelet CSZ–3 and Y-type zeolites, which are considerably thicker, are therefore not expected to show significant rhombohedral distortion despite the presence of similar twin fault bands.
Composition Variation Between Cu-Ni Crystallites using TEM and EDS
Authors: Sinha Pankaj K. , Cale Timothy S.
Published: March 2011

The distribution of nickel and copper between crystallites supported on high surface area silica (Cabosil HS5) has been studied using a Philips 400 series transmission electron microscope equipped with super twin lenses, a field emission gun and EDAX energy dispersive X-ray spectroscope. The same Ni-Cu catalysts have previously been characterized and used in cyclopropane hydrogenolysis kinetics. The good intercrystallite homogeneity found in a well reduced sample having 31% nominal copper validates a critical assumption made in these previous studies. Limited data on unreduced and partially reduced samples also highlight the need to carefully control the degree of reduction in kinetic and characterization studies.
Three-State Lattice-Gas Model of H-S on Pt(111)
Authors: Rikvold Per Arne , Collins Joseph B. , Hansen G. D. , Gunton J. D. , Gawlinski E. T.
Published: March 2011

We consider a three-state lattice-gas with nearest-neighbor interactions on a triangular lattice as a model for multicomponent chemi- and physisorption. By varying the lateral interaction constants between the adsorbate particles, this model can be made to exhibit either enhanced adsorption or poisoning (inhibited adsorption). We discuss here the conditions on the interaction constants that lead to poisoning. We present the results of a ground-state calculation and detailed numerical study of the phase diagram for a set of interactions that exhibits poisoning. We calculate the phase diagrams and adsorption isotherms by the finite-size scaling transfer-matrix method. We consider the result as a simple model for the coadsorption of Sulphur and Hydrogen on a Platinum (111) surface, with interaction constants estimated from experimental data. The resulting adsorption isotherms are in good agreement with experimental results.
Characterization by XRD High Resolution Electron Microscopy of Hydrodesulfuration Catalysts
Authors: Cruz J. , Avalos-Borja M. , Fuentes S. , Diaz G.
Published: March 2011

Recently a lot of work has attempted to correlate the activity of Co and Mo sulfide catalysts with observations of high resolution electron microscopy. Hydrodesulfuration (HDS) bulk sulfide catalysts are specially suited for this type of study. We prepared unsupported molybdenum sulfide by three methods: the homogeneous sulfide precipitation (HSP) (1), co-maceration (CM) (2), and impregnated thiosalt decomposition (ITD) (3). Pure cobalt sulfide was prepared only by HSP, and two Co-Mo sulfides in the ratios of 0.3 and 0.5 at. % were prepared by HSP and ITD. The samples were treated with a mixture of 20% H2S/H2 for 4 hrs. at 400 C. In all Co/Co+Mo mixtures the presence of Co9S8 and MoS2 was identified in both, ESP and ITD treatments. Characterization was done by high resolutibn electron microscopy. The ITD method can be considered a better method, as opposed to ESP for the preparation of mixed catalysts. This method produces poorly crystalline specimens that are usually associated to higher chemical activity.
Characterization of HDS and Syngas Catalysts Derived from Heterobimetallic Clusters
Authors: Curtis M. D. , Schwank J. , Penner-Hahn J. , Thompson L. , Baralt O. , Waldo G.
Published: March 2011

Discrete, organometallic clusters containing S, Mo, and Fe or Co have been deposited intact on metal oxide supports. These supported clusters are subjected to temperature programmed decomposition (TPDE) which causes loss of the organic ligands and produces catalysts active for CO hydrogenation and thiophene hydrodesulfurization (HDS). In-situ Mossbauer spectra reveal that the surface is remarkably uniform and that high spin ferrous iron is the predominate species (ca. 90%) under catalytic reaction conditions. EXAFS and XANES spectra show that the clusters are irreversibly oxidized by the surface at ca. 400 K under H2.
Adsorption and Reaction Mechanisms of Thiophene over Sulfided Ruthenium Catalysts
Authors: Cocco Ray A. , Tatarchuk Bruce J.
Published: March 2011

Adjustable (hydrogenolysis/hydrogenation) ratios (i.e., selectivity) of thiophene over sulfided ruthenium catalysts have been observed to depend on the method of presulfidization. Sulfidization in 10% H2S/H2 at 300–800K yielded a selectivity greater than 100, whereas a ratio of ca. 1 was noted after presulfidization in 100% H2S. The transition from one selectivity regime to another is reversible and can be changed via subsequent annealing or resulfidization procedures. X-Ray photoelectron spectroscopy shows similar results where sulfidization in 100% H2S yields: (i) a higher sulfur uptake with a corresponding 0.5 eV shift of the S 2P1/2–3/2 peaks to higher binding energy; (ii) multilayer sulfur incorporation at lower temperatures; and (iii) similar reversible behavior following subsequent annealing or resulfidization. Secondary ion mass spectroscopy and temperature programmed desorption studies also reveal that sulfur coverages affect thiophene adsorption, orientation and cracking on ruthenium surfaces.
Surface Chemical Characterization of Internal Interfaces Generated Within Thin-Film Fe-Ti Hydrides
Authors: Sanders Jeffrey H. , Tatarchuk Bruce J.
Published: March 2011

FeTi is considered an excellent candidate for the reversible storage of hydrogen and has been studied extensively in an attempt to understand the bulk activation needed for this material before use. Segregation of TiO2 to the surface has been noted to occur during activation explaining a slight loss of efficiency per hydride cycle, however, characterization by a host of bulk and surface sensitive techniques has not revealed the cause of this decomposition process.

10 nm FeTi samples were prepared in a UHV evaporator both with and without palladium coatings. Post treatment characterization was performed with backscatter conversion electron Mossbauer spectroscopy (CEMS), XPS and SIMS. CEMS is a powerful tool for providing stoichiometric, electronic, magnetic, chemical, and particle size information of iron at depths down to 100 nm. XPS and SIMS are useful to gain quantitative and chemical state information from the topmost 2 nm and the topmost monolayer, respectively. Activation treatments consisted of annealing at 573K and 623K followed by reduction at 573K. Results indicate that ppm levels of H2O in H2 are sufficient to decompose the FeTi alloy and produce TiO2 and Fe metal domains at the surface. Also, at 573K in vacuum, a solid-state reaction was found to occur between Fe oxides and FeTi to produce Fe metal and TiO2. The Pd-FeTi interface was probed with CEMS and the results demonstrate hydrogen dissociation and migration in the absence of alloy decomposition. Our approach uses nondestructive-depth profiling of non-Pd coated FeTi samples along with interfacial information from Pd-FeTi specimens to obtain unique insight into the decomposition process.
The Characterization of Hydrocarbon Intermediates in H-ZSM-5
Authors: Kofke T. J. Gricus , Gorte R. J. , Farneth W. E.
Published: March 2011

We have examined the adsorption of simple alcohols and 2-propanamine on H-ZSM-5 zeolites with Si/Al2 ratios between 38 and 520. Thermogravimetric analysis (TGA) demonstrated that most of the molecules display a clearly defined adsorption state corresponding to a coverage of one molecule per Al site. Temperature programmed desorption (TPD) and transmission infrared spectroscopy results for each of the molecules in this 1:1 adsorption state are consistent with adsorption being due to the transfer of a proton from the zeolite to the adsorbed molecule. These results provide additional evidence that carefully prepared H-ZSM-5 is a Bronsted acid, with one acid site per framework Al atom, in which all of the acid sites are identical in strength.
Brine Transport in the Bedded Salt of the Waste Isolation Pilot Plant (wipp): Field Measurements and a Darcy Flow Model
Authors: Mctigue David F. , Nowak E. James
Published: March 2011

Brine flow has been measured to unheated boreholes for periods of a few days and to heated holes for two years in the WIPP facility. It is proposed that Darcy flow may dominate the observed influx of brine. Exact solutions to a linearized model for one-dimensional, radial flow are evaluated for conditions approximating the field experiments. Flow rates of the correct order of magnitude are calculated for permeabilities in the range 10−21–1020 m2 (1–10 nanodarcy) for both the unheated and heated cases.
Modelling approach to the prediction of Equilibrium Phase Distribution in Slag-Cement Blends and their Solubility Properties.
Authors: Glasser Frederik P. , Macphee Donald E. , Lachowski Eric E.
Published: March 2011

Blended cements containing mixtures of granulated blast-furnace slag (BFS) and Portland cement give low permeability matrices with initially favourable leach characteristics. Their retention arises from a combination of physical and chemical effects which include high pH and sorption. It is not practical though, in either laboratory or site-based experimentation, to determine changes in matrix chemistry over long timescales and the development of realistic models for long-term property predictions therefore becomes increasingly important. This paper pursues the development of such a model enabling changes in chemical and mineralogical balances during ageing to be predicted.

Phase development is assessed in the system CaO-Al2O3-SiO2-MgO-H2O. In the relevant composition range, the phases occurring include crystalline hydrates: portlandite, (Ca(OH)2); gehlenite hydrate, (2CaO.Al2O3.SiO2.8H2O); a hydrotalcite-structured phase (nominally 6MgO.Al2O3.(OH)x.yH2O). an AFm type phase, (nominally 4CaO.Al2O3 SO3.12H2O); and a poorly crysiallised c~lcium silicate hydrogel, C-S-H. All five phases are observed to occur together in slag-cements which are still hydrating. Given, as input, the chemical analyses of both the slag and the cement, and the initial blending proportions, the model predicts the equilibrium distribution between the five components and additionally, the Ca/Si ratio of the C-S-H. The aqueous chemistry in the system is predicted from the calculated phase distribution and appropriate solubility products.
Effect of Ionizing Radiation on Moist Air Systems
Authors: Reed Donald T. , Van Konynenburg Richard A.
Published: March 2011

The radiation chemistry of nitrogen/oxygen/water systems is reviewed. General radiolytic effects in dry nitrogen/oxygen systems are relatively well characterized. Irradiation results in the formation of steady state concentrations of ozone, nitrous oxide and nitrogen dioxide. In closed systems, the concentration observed depends on the total dose, temperature and initial gas composition. Only three studies have been published that focus on the radiation chemistry of nitrogen/oxygen/water homogeneous gas systems. Mixed phase work that is relevant to the gaseous system is also summarized. The presence of water vapor results in the formation of nitric acid and significantly changes the chemistry observed in dry air systems. Mechanistic evidence from the studies reviewed are summarized and discussed in relation to characterizing the gas phase during the containment period of a repository in tuff.
Evolution of the Groundwater Chemistry Around a Nuclear Waste Repository.
Authors: Haworth A. , Sharland S. M. , Tasker P. W. , Tweed C. J.
Published: March 2011

Perturbations to the natural chemistry of the geology surrounding a nuclear waste repository may affect the overall nuclide release rates through properties such as their solubilities and sorption characteristics. In this paper, we develop some of the necessary techniques to construct a detailed research model of the evolution of the groundwater under the influence of the backfill material. These techniques involve various extensions to the coupled ionic migration and chemical equilibria code, CHEQMATE and are used in the first stages of such a model. Although the design and location of a deep low- and intermediate-level nuclear waste repository have not yet been finalised in the U.K., we have considered a concrete backfill material embedded in a clay geology. Preliminary results suggest that over timescales of about a thousand years the natural buffering action of the clay against changes in pH has a significant effect on the scale of perturbation by the ingress of highly alkaline porewater. It seems likely therefore that this type of modelling will have considerable relevance to the safety assessment models.
Xps and Xrd Studies of Uranium Rich Minerals from Cigar Lake, Saskatchewan
Authors: Sunder S. , Taylor P. , Cramer J. J.
Published: March 2011

Samples of uranium ore from the 1,300 million year old Cigar Lake deposits in northern Saskatchewan have been investigated using X ray Photoelectron Spectroscopy (XPS) and X ray Diffraction (XRD). The XPS spectra showed the peaks for U, Pb, 0, C, Si, Ca and Mg. Analysis of highresolution XPS spectra showed that the oxidation state of uranium in these minerals is equal to, or lower than, that of U3O7. The XRD data confirm the presence of an oxidized phase, most likely α U3O7., in addition to UO2. The low U(VI)/U(IV) ratio in these minerals is consistent with the low uranium concentration found in groundwater in contact with these uranium minerals. The relevance of these results to the disposal concept of used nuclear fuel in the Canadian Nuclear Fuel Waste Management Program is discussed.
An Annealing Study of Alpha-Decay Damage in Natural UO2 and ThO2
Authors: Stout P. J. , Lumpkin G. R. , Ewing R. C. , Eyal Y.
Published: March 2011

Isochronal annealing (100°–1200°C) of alpha-decay damage was performed on UO2 and ThO2 and isothermal annealing (400°C and 750°C) of UO2 was done to determine the change in unit cell parameter (UO2: ao = 5.501Å to 5.458Å ± 0.001; ThO2: ao = 5.548Å to 5.523Å ± 0.001), strain, and crystallite size (data inconclusive). Two recovery stages (UO2: Stage I at ≈225°C, Stage II at ≈675°C; ThO2: Stage I at ≈250°C, Stage II at ≈550°C) were observed for each. Strain decreased with temperature for both, but never completely recovered in either (UO2 final value: ≈2.37 × 10−3; ThO2 final value: ≈2.06 × 10−3).
Performance Assessment of Glass As A Long-Term Barrier To The Release of Radionuclides Into The Environment
Authors: Grambow B. , Lutze W. , Ewing R. C.
Published: March 2011

Performance assessment of high-level nuclear waste forms in a repository must cover periods of time on the order of hundreds of thousands of years. There has rarely been a need to extrapolate the properties of a material over such long periods of time (except in the geologic sciences, e.g., the evaluation of long-term weathering effects based on results from laboratory experiments) and there has never been a more important need to make accurate and -verifiable “predictions” of the long-term materials performance. The results of such extrapolations could affect decisions concerning the selection of a repository and the number and types of barriers that are required to insure isolation over long periods of time. In typical safety analyses [1,2] waste form corrosion is described by a single constant rate, and no effort is made to evluate whther the modal of the “source term” can be substantiated or verified by comparison similar or analogous processes [3].
Leaching Tc-99 from SRP Glass in Simulated Tuff and Salt Groundwaters
Authors: Bibler N. E. , Jurgensen A. R.
Published: March 2011

Results of leach tests with Tc-99 doped SRP borosilicate waste glass are presented. The glass was prepared by melting a mixture of SRP 165 powdered frit doped with a carrier free solution of Tc-99 at 1150°C. Dissolution of portions of the resulting glass indicated that the Tc-99 was distributed homogeneously throughout the glass. Static leach tests up to 90 days were performed at 90°C in J-13 tuff groundwater or WIPP brine A at a SA/V of 100m−1. Normalized mass losses were calculated for Tc-99 as well as all the major elements in the glass. Results indicated that under ambient oxidizing conditions Tc-99 leached no faster than the glass-forming elements of the glass. In J-13 water, Tc-99 leached congruently with B. In WIPP brine A, it leached congruently with Si. Leach rates for Li were higher in both groundwaters, probably due to a contribution from an ion exchange mechanism. Leach tests were performed under reducing conditions in J-13 water by adding Zn/Hg amalgam to the leachate. In these tests the pH increased significantly, probably because of the reaction of the amalgam with the water. In a 21-day test, the pH Increased to 13 and leach rates for the glass were very high. Even though there was significant dissolutiop of the glass, the normalized mass loss based on Tc-99 was only 0.02g/m2. This result and the fact that reducing conditions at normal pH values do not significantly affect the dissolution of the glass, indicate that the low concentrations for Tc-99 obtained under reducing conditions are due to its solubility and not due to an increased durability of the glass.
Influence of Groundwater Composition on Glass Leaching and Actinide Speciation
Authors: Bidoglio G. , Offermann P. , De Plano A. , Lazzari G. P.
Published: March 2011

Flow-leaching studies were conducted using borosilicate glass beads containing 241-Am, 237-Np and 238-Pu. The leachates were a bicarbonate groundwater and a brine. Tests were carried out unger oxidizing and reducing conditions. In bicarbonate groundwater (2.6 × 10−3M NaHCO3, pH 8.4) under oxic conditions, steady-state leach-rates were found to increase in the order Pu∼Am<Np, with Np species leached congruently with sodium. Direct identification of Np carbonate complexes in the leachate was carried out by. electromigration. A reversed order of leachability was obtained in a reducing environment. In this case, Pu was found to be associated with particulate matter. In a salt brine leachate (5.4 M NaCl, pH∼6) a periodic cycle of increasing-decreasing concentrations was observed under reducing conditions. This was found to be dependent upon the redox state of actinides. Radionuclide adsorption into an unstable gel layer was postulated.
The Long-Term Corrosion and Modelling of Two Simulated Belgian Reference High-Level Waste Glasses
Authors: Van Iseghem P. , Grambow B.
Published: March 2011

The corrosion behaviour in distilled water of two simulated candidate high level waste borosilicate glasses (SAN602519L3C2 and SM58LW11) his been investigated at 90°C for different SA/V condition's 10, 100, 7800 m−1). The experimental data were modelled using the PHREEQE and GLASSOL computer codes. The model is quite successful for describing the corrosion behaviour, using experimentally derived values for the forward rate, silica saturation and the final rate. GWss SAN60 is more stable than glass SM58 at SA/V values of 10 and 100 m−1, but in the long term the relative performance is inverse. Indeed, the high Al content of SAN60 induces the creation of analcime crystals after SiO2 has reached its saturation concentration in solution, which cause an enhancement of the final rate of dissolution of the glass; for SM58 on the contrary the SiO2 solution is a stable condition.
Borosilicate HLW Glass Leaching in Silica Saturated Solution
Authors: Lanza F. , Manara A. , Mammarella L. , Blasi P. , Ceccone G.
Published: March 2011

The aim of these measurements is to study how a silica saturated solution influences leaching from a HLW glass matrix. Cylindrical samples of I117 borosilicate glasses were suspended in polycarbonate vials containing a SiO2 saturated solution and leached at temperature of 50 or 80°C for different times (from 1/2 to 28 days). Mass loss, X-ray photoelectron spectroscopy (XPS) and nuclear reaction techniques were applied for post leaching tests on the glass samples.

Analysis of boron and sodium released from the glass were performed in the leachate. Sodium and boron release followed a square root time dependence at all the observed leaching times.

XPS measurements revealed a surface increase of silicon content with respect to unleached samples, with aluminium showing the same behaviour as silicon. The presence of the layer enriched in silicon and aluminium does not stop the release of sodium and boron, whereas the mass loss does slow down because of the formation of aluminio-silicate compounds.
Corrosion Studies of A216 Grade WCA Steel in Hydrothermal Magnesium-Containing Brines
Authors: Haberman J. H. , Frydrych D. J.
Published: March 2011

The U.S. Department of Energy's Salt Repository Project (SRP) is investigating the general corrosion resistance of cast mild steel as a candidate material for waste package containers. Evaluation of this material is being performed at the Pacific Northwest Laboratory in environments simulating expected repository conditions.

General corrosion studies of mild steel (ASTM A216 grade WCA) in the as-cast and normalized conditions were conducted in hydrothermal halitesaturated (saturated at ambient temperature) brine environments simulating a “dissolution” and an “inclusion” brine. Corrosion tests were also performed in brines similar to the inclusion brine but containing magnesium concentrations ranging from 1000 to 30,000 ppm to investigate the effect of magnesium on the corrosion behavior.

Corrosion rates of the cast mild steel were found to increase with increasing temperature and with increasing magnesium concentration. Some possible mechanisms that explain the observed behavior are presented.
Characterization of Fly Ash Reactivity by Isothermal Conduction Calorimetry
Authors: Cook David J. , Cao H. Trinh , Baweja Daksh
Published: March 2011

The reactivity of fly ash is generally difficult to determine because neither a single physical nor chemical property nor any combination of these can be used characterize a particular sample completely. A direct reflection of this is the range of pozzolanicity tests proposed by standards worldwide and the applicability and relevance of such tests is currently being debated.

In many countries, codes of practice and standards relating to fly ashes are currently under review. Some work has been carried out in countries including Australia, United Kingdom, and the United States on commercial fly ashes with a view to possible classification and implementation into standards [1-2]. It is generally recognized that current standards on fly ash do have some inadequacies with regard to performance prediction when included in concrete. Fineness requirements for fly ash for use in structural concrete (BS3892: Part 1) in the United Kingdom are currently being debated [2] with many workers suggesting that it would be possible to produce durable concrete with ashes which would not comply with the requirements of the standard [3].
Phase Characterization of Coal-Fueled Turbine Engine Deposits
Authors: Schields Paul J. , Spiro Clifford L. , Koch Edward F.
Published: March 2011

A major consideration in the development of a coal-fueled turbine engine is to minimize the deleterious effect of products of combustion (POC) on the engine components. Characterization of the POC phases is important for understanding and regulating combustion, emissions, deposition, corrosion and erosion behavior. POC phases deposited from the combustion of beneficiated bituminous coal in turbine simulators were characterized using x-ray techniques and electron microscopy. The phase assemblages include plagioclase feldspars, feldspathoids, spinels, anhydrite, hematite and noncrystalline material. The deposits had the form of a partially sintered powder and a slag. Differences in the phase composition of the powder and slag were determined by xray analysis and observed in the feldspar/spinel lattice parameters. The morphology, phase associations, compositional differences of the powder and slag, and heat treatment experiments indicate that the slag is largely formed by fusion of the powder. The hypothetical fusion process decomposes the CaSO4 in the powder and the released calcia is incorporated into the plagioclase solid solution powder phase. The additional alumina required for charge neutrality in the plagioclase comes from the powder's Al-rich spinel which transforms to an Al-poor spinel. These phase characterization results are useful for assessing and optimizing deposit remediation methods.