The Henry's law type constants of OH and HO{sub 2} have not been experimentally determined for obvious reasons: it is extremely difficult to measure the concentrations of these reactive species in either the gas phase or the aqueous phase, let alone simultaneously in both phases. At a more fundamental level, because these radicals react rapidly in both phases, compared with mass-transfer rates characterizing typical laboratory multi-phase systems, the gas-liquid equilibrium which is necessary for such measurements to be feasible is typically not attainable. Consequently, the Henry's law constants of these radicals are traditionally evaluated from the free energy of solution, {Delta}{sub sol}G{sup 0}(X) accompanying the process of transferring a molecule X from the gas phase, denoted g, to the aqueous phase, a, i.e. X{sub g} {rightleftharpoons} X{sub a} (9.10); using the equation {Delta}{sub sol}G{sup o}(X) = -RT ln k{sub H} (9.11); {Delta}{sub sol}G{sup o}(X) is defined as {Delta}{sub sol}G{sup o}(X) = {Delta}{sub f}G{sup o}(X){sub a} - {Delta}{sub f}G{sup o}(X){sub g} (9.12) where the free energies of formation of X in the gas phase and in the aqueous phase are typically evaluated using thermochemical cycles.

High-pressure, high-temperature scanning tunneling microscopy (HPHTSTM) was used to study adsorbate structures and reactions on single crystal model catalytic systems. Studies of the automobile catalytic converter reaction [CO + NO {yields} 1/2 N{sub 2} + CO{sub 2}] on Rh(111) and ethylene hydrogenation [C{sub 2}H{sub 4} + H{sub 2} {yields} C{sub 2}H{sub 6}] on Rh(111) and Pt(111) elucidated information on adsorbate structures in equilibrium with high-pressure gas and the relationship of atomic and molecular mobility to chemistry. STM studies of NO on Rh(111) showed that adsorbed NO forms two high-pressure structures, with the phase transformation from the (2 x 2) structure to the (3 x 3) structure occurring at 0.03 Torr. The (3 x 3) structure only exists when the surface is in equilibrium with the gas phase. The heat of adsorption of this new structure was determined by measuring the pressures and temperatures at which both (2 x 2) and (3 x 3) structures coexisted. The energy barrier between the two structures was calculated by observing the time necessary for the phase transformation to take place. High-pressure STM studies of the coadsorption of CO and NO on Rh(111) showed that CO and NO form a mixed (2 x 2) structure …

In this reporting period, a milestone was achieved by commencement of testing and operation of the sub-scale hybrid direct fuel cell/turbine (DFC/T{reg_sign}) power plant. The operation was initiated subsequent to the completion of the construction of the balance-of-plant (BOP) and implementation of process and control tests of the BOP for the subscale DFC/T hybrid system. The construction efforts consisted of finishing the power plant insulation and completion of the plant instrumentation including the wiring and tubing required for process measurement and control. The preparation work also included the development of procedures for facility shake down, conditioning and load testing of the fuel cell, integration of the microturbine, and fuel cell/gas turbine load tests. At conclusion of the construction, the process and control (PAC) tests of BOP, including the microturbine, were initiated.

OAK B135 The formation of metastable crystalline phases in lithium disilicate glass has been a subject of controversy for decades. Here, one aspect of this problem relating to the stability of these non-equilibrium phases when glasses are heated for extended time periods in the nucleation regime is addressed. The results of a systematic experimental investigation on the persistence of metastable phases and the factors that may influence the appearance of such phases, e.g., water content, impurities, glass composition, and glass preparation procedure are presented. Growth rates of lithium disilicate crystals in lithium disilicate glass are measured as a function water concentration in the glass and of temperature in the deeply undercooled regime. The growth rate data obtained in this work are combined with data reported in the literature and used to assess the applicability of standard models of crystal growth for the description of experimental results over a very broad temperature range. The reduced growth rate versus undercooling graph is found to consist of three regimes. For undercoolings less than 140°C, the reduced growth rate curve is suggestive of either 2-D surface nucleation or screw dislocation growth. For undercoolings greater than 400°C, the reduced growth rate plot suggests the operative …

In this program the teams at Penn State University (PSU), Sandia National Laboratories (SNL), DCH Technology (DCHT), and Air Products and Chemicals Inc. (APCI), have aggressively pursued engineering solutions to eliminate barriers to solid-state chemiresistor hydrogen sensor technology. The metallurgical effects of alloying palladium with nickel have been shown to prevent phase transitions in the thin films at high H2 overpressures, making the devices more suitable for IOF process conditions. We investigated the use of thin, semi-permeable membranes that protect the catalytic surface from poisoning or other undesirable surface reactions that would otherwise reduce sensitivity or operability in harsh IOF process environments. The results of this project have provided new insight into the effects of metallurgy and protective coatings on device behavior, and open new avenues for research in this field. Commercialization of this sensor technology could be easily achieved, although not yet realized. The benefits to society, once this technology is commercialized, is a dramatic cost and energy savings to the industry, which employs these sensors. In addition, the fundamental understandings gained in this program could have an impact on both cost and safety in the future hydrogen economy utilizing hydrogen fuel cells and hydrogen storage.

About 1.5 x 10{sup 12} positive ions are predicted to be required to disrupt the focusing (for 0.25 cm radius and 0.2 electric neutralization fraction). Beam electron collisions are predicted to produce this number in 20 ns with 6 x 10{sup 15} water molecules/cm{sup 2}. Electron avalanching is predicted to be intense at time zero in a gas layer about 10{sup -3} cm thick with 1.4 x 10{sup 16} cm{sup -2}. With increasing time, space charge reduces the E-field and so the avalanching decreases. With 0.25 cm radius, 1.9 x 10{sup 11} are predicted in 0.6 ns and with 1 cm radius, 7.4 x 10{sup 11} are predicted in 1.5 ns.

In this paper, we report on the halo formation and emittance growth driven by a parametric resonance during mismatched beam-beam collisions. In the regime of the weak-strong beam-beam interaction, if two beams have the same machine tunes, on-axis head-on collisions between a mismatched strong beam and a weak beam will not cause the formation of halo. However, if the two beams collide with an initial offset, the beam-beam force from the mismatched strong beam can cause halo formation and emittance growth in the weak beam. Meanwhile, if two beams have different machine tunes, for opposite charged colliding beams, when the machine tune of the weak beam is smaller than that of strong beam, there is emittance growth in the weak beam. When the machine tune of the weak beam is larger than that of the strong beam, there is little emittance growth. In the regime of strong-strong beam-beam interaction, halo is formed in both beams even when the two beams collide head-on on the axis with equal machine tunes. This puts a strong requirement for a good beam match during the injection to colliders in order to avoid the emittance growth.

This report summarizes the activities and major accomplishments for the Idaho National Engineering and Environmental Laboratory (INEEL) Advanced Radiotherapy Research Program for calendar year 2002. Topics covered include computational dosimetry and treatment planning software development, medical neutron source development and characterization, and boron analytical chemistry.

This report summarizes the work done during the entire project period, between October 1, 1999 and March 31, 2003, which includes a six-month no-cost extension. During the project, eight research papers have, either been, published, accepted for publication, or submitted for publication. In addition, several presentations have been made in technical meetings and workshops. The project also has provided support for four graduate students working towards advanced degrees. The principal technical objective of the project was to analyze the role of electrode microstructure on solid oxide fuel cell performance. Prior theoretical work conducted in our laboratory demonstrated that the particle size of composite electrodes has a profound effect on cell performance; the finer the particle size, the lower the activation polarization, the better the performance. The composite cathodes examined consisted of electronically conducting perovskites such as Sr-doped LaMnO{sub 3} (LSM) or Sr-doped LaCoO{sub 3} (LSC), which is also a mixed conductor, as the electrocatalyst, and yttria-stabilized zirconia (YSZ) or rare earth oxide doped CeO{sub 2} as the ionic conductor. The composite anodes examined were mixtures of Ni and YSZ. A procedure was developed for the synthesis of nanosize YSZ by molecular decomposition, in which unwanted species were removed by leaching, …

Multiple access (MA) in UWB communication is an area of active research. In this paper we introduce and study the performance of a new MA scheme in the context of multiple transmitted-reference short duration (nsec) chirp pulses in the presence of additive white Gaussian noise (AWGN). The transmitted-reference (T-R) receiver is extended using multiple orthogonal pulses. The proposed UWB receiver samples the receiver autocorrelation function (ACF) at both zero- and non-zero lags, thus sampling and matching the shape of ACFs rather than just the shape of the received pulses. Sampling of non-zero ACF lags is a significant new approach. The scheme proposed in this paper is a step towards combining the multi-pulse approach and T-R modulation in a multiple access ultra wideband (MA-UWB) communications system. Improved bit error rate performance over a conventional zero-lag receiver (i.e. energy detection receiver) is demonstrated by simulation. Analytical expressions for the system BER are also derived and confirmed through simulations for the system.

The solubility of gases in water and other aqueous media such as seawater and more concentrated solutions is central to the description of the uptake and reactions of these gases in aerosols, precipitation, surface water and other aqueous media such as the intracellular fluids of plants and animals. It is also pertinent to sampling of soluble atmospheric gases in aqueous medium for analytical purposes. This book presents evaluated summaries of data pertinent to the solubility of gases in aqueous media. This chapter introduces the terminology by which this solubility is described and the pertinent units and presents examples of applications pertinent to atmospheric chemistry. As is seen below, a variety of units have been and continue to be employed for gas solubility data, so some attention must be given to this subject. As this is an IUPAC publication, every effort is made to employ units that are consistent with the International System of Units (Systeme International, SI). However, in IUPAC publications of solubility data it is usual to publish data in the original units in addition to SI units. The consistency of SI makes this system of units convenient for application in atmospheric chemistry and related disciplines. However, as elaborated …

Three decades ago John Cowley and his group at ASU achieved high-resolution electron microscope images showing the crystal unit cell contents at better than 4Angstrom resolution. Over the years, this achievement has inspired improvements in resolution that have enabled researchers to pinpoint the positions of heavy atom columns within the cell. More recently, this ability has been extended to light atoms as resolution has improved. Sub-Angstrom resolution has enabled researchers to image the columns of light atoms (carbon, oxygen and nitrogen) that are present in many complex structures. By using sub-Angstrom focal-series reconstruction of the specimen exit surface wave to image columns of cobalt, oxygen, and lithium atoms in a transition metal oxide structure commonly used as positive electrodes in lithium rechargeable batteries, we show that the range of detectable light atoms extends to lithium. HRTEM at sub-Angstrom resolution will provide the essential role of experimental verification for the emergent nanotech revolution. Our results foreshadow those to be expected from next-generation TEMs with Cs-corrected lenses and monochromated electron beams.

Polycrystalline SiC samples hot-pressed with aluminum, boron, and carbon sintering additions (ABC-SiC) were characterized using transmission electron microscopy. The study focused on the effects of high temperature treatment on microstructure.