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To compare cardiopulmonary variables and blood gas analytes in guinea pigs (Cavia porcellus) during anesthesia with and without abdominal carbon dioxide (COProspective experimental trial.A total of six intact female Hartley guinea pigs.A crossover study with sequence randomization for IAP and intubation status was used. The animals were sedated with intramuscular midazolam (1.5 mg kgIntubated guinea pigs had significantly higher pH and lower partial pressure of COAlthough the oral anatomy of guinea pigs makes endotracheal intubation difficult, capnoperitoneum during anesthesia induces marked hypercapnia in the absence of mechanical ventilation. An IAP of 4 mmHg should be further evaluated for laparoscopic procedures in guinea pigs because hypercapnia may be less severe than with 6 mmHg.

OBJECTIVE To describe the clinical presentation, treatment, and treatment outcomes for companion rats (Rattus norvegicus) diagnosed with lymphoma. ANIMALS All rats that presented to the exotics service and underwent postmortem examination during the time period of 2008 through 2020 were evaluated. PROCEDURES The medical records of 35 rats were evaluated for an ante- or postmortem diagnosis of lymphoma. Cases with a diagnosis of lymphoma were further reviewed for signalment, presenting complaint, clinical signs observed on physical exam, diagnostic testing performed, and treatments administered. Postmortem gross and histologic findings were reviewed. RESULTS 7 out of 35 rats were diagnosed with lymphoma, either ante-mortem or postmortem. The most common presenting complaint that was present in all rats with lymphoma was respiratory abnormalities. Five out of 7 rats had radiographs performed, all of which had abnormalities noted in the thoracic cavity including pulmonary nodules, cranial mediastinal widening, or alteration to the cardiac silhouette. Diagnosis via cytologic aspirates was performed in 2 cases and each was diagnostic for lymphoma; however, even with treatment, survival time following initiation of chemotherapy was short (less than or equal to 24 days). The definitive diagnosis in the remainder of the cases was via necropsy. CLINICAL RELEVANCE Results suggest that lymphoma is a common neoplastic disease in rats and a thorough diagnostic work-up is indicated in any rat that presents for general malaise or respiratory signs.

OBJECTIVE To evaluate pneumoperitoneal volumes (laparoscopic working space) in guinea pigs (Cavia porcellus) undergoing pneumoperitoneum via carbon dioxide insufflation at different intra-abdominal pressures (IAPs) (4, 6, and 8 mm Hg) and recumbencies (dorsal, right lateral, and left lateral). ANIMALS Six 3- to 4-month-old sexually intact female Hartley guinea pigs. PROCEDURES Guinea pigs were anesthetized, intubated, and had an abdominal insufflation catheter placed. A baseline abdominal CT scan was performed. Guinea pigs underwent insufflation, with each IAP given in a random order for 10 to 15 minutes with a washout period of 5 minutes between pressures. Abdominal CT scans were acquired at each IAP and at each recumbency. Pneumoperitoneal volumes were calculated using software. RESULTS Increases in IAP increased working space significantly (P < .001). The 6- and 8-mm Hg pressures increased working space from 4 mm Hg by 7.3% and 19.8%, respectively. Recumbent positioning (P = .60) and body weight (P = .73) did not affect working space. Order of IAP had a significant (P = .006) effect on working space. One of the guinea pigs experienced oxygen desaturation and bradycardia at 6- and 8-mm Hg IAP. CLINICAL RELEVANCE Although an increased working space occurred at 6 and 8 mm Hg compared to 4 mm Hg, further research is needed concerning the cardiovascular effects of pneumoperitoneum in guinea pigs to determine whether those higher IAPs are safe in this species. An IAP of 6 mm Hg can be considered for laparoscopic cannula placement, followed by a lower IAP for laparoscopic procedures.

OBJECTIVE To compare stress markers, gastrointestinal motility, and behavioral indicators of pain between guinea pigs undergoing pneumoperitoneum with carbon dioxide (CO2) and control guinea pigs. ANIMALS Fourteen 4- to 5-month-old intact female Hartley guinea pigs. PROCEDURES Guinea pigs were randomized to receive insufflation or serve as controls (anesthesia and abdominal catheter placement without insufflation), with 7 animals/group. Insufflated animals underwent 6 mm Hg of CO2 pneumoperitoneum for 30 minutes. Afterward, results for vital signs, blood glucose, fecal cortisol, appetite, fecal output, and behaviors (via video recording) were compared between the 2 groups. RESULTS There was no difference between groups and over time for body temperature, heart rate, fecal output in grams, pellets consumed, blood glucose, and fecal cortisol. Guinea pigs that underwent insufflation had significantly more fecal pellets at 36 hours after the procedure. Several behaviors were expressed similarly between groups and over time, such as body turns, incomplete movement, rearing, lying down, drinking, and hiding. Coprophagy occurred less often in the insufflated versus noninsufflated group at 12 h postprocedure but was similar between groups at other time points. At 60 hours after the procedure, insufflated animals spent less time squinting compared to noninsufflated animals. Other behaviors were differentially expressed over time but not between treatments. CLINICAL RELEVANCE Overall, there were no major differences in appetite, stress markers, and behaviors between insufflated and control guinea pigs. CO2 insufflation did not appear to cause undue pain or stress in guinea pigs and may be a reasonable technique to use during laparoscopy.

Radiation therapy (RT) is being utilized more commonly for rabbit thymomas due to high perioperative mortality rates with surgery. Median overall survival times reported for rabbit thymomas treated with a variety of RT protocols and techniques range from 6 months to greater than 2 years. As thymomas are radiation-responsive tumours and may shrink rapidly after RT, adaptive radiotherapy (ART) is often warranted. The purpose of this single-institution retrospective case series was to investigate the tumour volume reduction during RT, the frequency of replanning during RT, and survival time in rabbit thymomas treated using intensity-modulated/image-guided radiation therapy (IMRT/IGRT) and a weekly hypofractionated protocol delivering a total dose of 30 Gy. Ten rabbits met the inclusion criteria from October 2014 to October 2019. The median progression-free survival was 561 days and the median overall survival was 634 days (range: 322-1118 days). The tumour volume gradually decreased with each RT fraction. On post-hoc analysis, only the first RT fraction was associated with a significant GTV reduction (of more than 50% on average, p .001). All subsequent RT fractions did not further reduce the GTV significantly (p .06). Hypofractionated RT using a weekly protocol of 5 fractions of 6 Gy is a reasonable option to treat rabbit thymomas and replanning should be anticipated. The results of this study support the use of RT to rapidly relieve thymoma-induced dyspnoea in rabbits.

Cancer is a genetic disease resulting from germline or somatic genetic aberrations. Rapid progress in the field of genomics in recent years is allowing for increased characterization and understanding of the various forms of the disease. The Ontario-wide Cancer Targeted Nucleic Acid Evaluation (octane) clinical trial, open at cancer centres across Ontario, aims to increase access to genomic sequencing of tumours and to facilitate the collection of clinical data related to enrolled patients and their clinical outcomes. The study is designed to assess the clinical utility of next-generation sequencing (ngs) in cancer patient care, including enhancement of treatment options available to patients. A core aim of the study is to encourage collaboration between cancer hospitals within Ontario while also increasing international collaboration in terms of sharing the newly generated data. The single-payer provincial health care system in Ontario provides a unique opportunity to develop a province-wide registry of ngs testing and a repository of genomically characterized, clinically annotated samples. It also provides an important opportunity to use province-wide real-world data to evaluate outcomes and the cost of ngs for patients with advanced cancer. The octane study is attempting to translate knowledge to help deliver precision oncology in a Canadian environment. In this article, we discuss the background to the study and its implementation, current status, and future directions.

Multilayer thin film of Gd-doped ceria and zirconia have been grown by sputter-deposition on α-Al2O3 (0001) substrates. The films were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The Gd-doped ceria and zirconia layers had the fluorite structure and are highly textured such that the (111) plane of the films parallel to the (0001) plane of the α-Al2O3. The epitaxial relationship can be written as $$ ( 1 1 1)_{{{\text{ZrO}}_{ 2} /{\text{CeO}}_{ 2} }} //(000 1)_{{{\text{Al}}_{2} {\text{O}}_{3} }} $$ and $$ [ 1 1{-}2]_{{{\text{ZrO}}_{2} /{\text{CeO}}_{2} }} //[ - 2 1 10]_{{{\text{Al}}_{2} {\text{O}}_{3} }} $$ , respectively. The absence of Ce3+ features in the XPS spectra indicates that the Gd-doped ceria films are completely oxidized. The ionic conductivity of this structure shows great improvement as compared with that of the bulk crystalline material. This research provides insight on designing of material for low temperature electrolyte applications.

We examined the reduction of different size hematite (α-Fe2O3) nanoparticles (average diameter of 11, 12, 30, 43, and 99 nm) by the dissimilatory iron reducing bacteria (DIRB), Shewanella oneidensis MR-1, to determine how S. oneidensis MR-1 may utilize these environmentally relevant solid-phase electron acceptors. The surface-area-normalized-bacterial Fe(III) reduction rate for the larger nanoparticles (99 nm) was one order of magnitude higher than the rate observed for the smallest nanoparticles (11 nm). The Fe(III) reduction rates for the 12, 30, and 43 nm nanoparticles fell between these two extremes. Whole-cell TEM images showed that the mode of Fe2O3 nanoparticle attachment to bacterial cells was different for the aggregated, pseudo-hexagonal/irregular and platey 11, 12, and 99 nm nanoparticles compared to the non-aggregated 30 and 43 nm rhombohedral nanoparticles. Due to differences in aggregation, the 11, 12, and 99 nm nanoparticles exhibited less cell contact and less cell coverage than did the 30 and 43 nm nanoparticles. We hypothesize that S. oneidensis MR-1 employs both indirect and direct mechanisms of electron transfer to Fe(III)-oxide nanoparticles and that the bioreduction mechanisms employed and Fe(III) reduction rates depend on the nanoparticles’ aggregation state, size, shape and exposed crystal faces.

Reduced operating temperatures (600– 800 ∘ C ) of solid oxide fuel cells (SOFCs) may enable the use of inexpensive ferritic steels as interconnects. Due to the demanding SOFC interconnect operating environment, protective coatings are required to increase long-term stability. In this study, large area filtered arc deposition (LAFAD) and hybrid filtered arc-assisted electron beam physical vapor deposition (FA-EBPVD) technologies were used to deposit two-segment coatings with Cr–Al–Y–O nanocomposite bottom segments and Mn–Co–O spinel-based top segments. Coatings were deposited on ferritic steels and subsequently annealed in air for various times. Surface oxidation was investigated using SEM/EDS, XRD and RBS analyses. Cr-volatilization was evaluated by transpiration and ICP–MS analysis of the resultant condensate. Time-dependent area specific resistance (ASR) was studied using the four-point technique. The oxidation behavior, Cr volatilization rate, and ASR of coated and uncoated samples are reported. Significant long-term ( > 1000 h ) surface stability, low ASR, and dramatically reduced Cr-volatility were observed with the coated specimens. Improvement mechanisms, including the coating diffusion barrier properties and electrical conductivity are discussed.

Long-term historic spills of uranium at the 300 Area fuel fabrication site (58,000 kg of disposed uranium over 32 yr) and at the 200 East Area BX tank farm (7000 kg of spilled uranium in one event), both within the Hanford formation in the Hanford Site, Washington State, were investigated by subsurface sampling and subsequent microscale investigations of excavated samples. The 200 Area sediments contained uranyl silicate mineralization (sodium boltwoodite) in restrictive microfractures in granitic clasts, in the vadose zone over a narrow range in depth. Well logging and column experiments indicated that tank wastes migrated deeper than observed in core samples. The 300 Area sediments included metatorbernite and uranium at low concentrations associated with detrital aluminosilicates, along with other mineral phases that could accommodate uranyl, such as uranophane and calcium carbonate. The association of contaminant uranyl with Hanford formation sediments provided a persistent source of uranium to groundwater. The results of both studies suggest that the formation of secondary solid uranyl-bearing phases infl uences the subsequent release of uranium to the environment and that our understanding of these processes and individual waste sites is incomplete.

Thin film of silicon germanium (Si1-xGex) with tailored composition was grown on Si (100) substrate at 650oC in an ultrahigh vacuum molecular beam epitaxy system. The nominal x-value is ranged from 0 to 0.14. The quality of the film was investigated by Rutherford backscattering spectrometry (RBS) in random and channeling geometries, glancing angle x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy (EDX), and atomic force microscopy (AFM). RBS/Channeling measurements indicate that the strain associated with lattice mismatch is compressive in the film. Both RBS and EDX analyses indicate the compositional graded incorporation of Ge in the film with x ranging from 0 to 0.14. The film shows island growth with each island centering around an interface dislocation.

Shewanella oneidensis MR-1 is purported to express outer membrane cytochromes (e.g., MtrC and OmcA) that transfer electrons directly to Fe(III) in a mineral during anaerobic respiration. A prerequisite for this type of reaction would be the formation of a stable bond between a cytochrome and an iron oxide surface. Atomic force microscopy (AFM) was used to detect whether a specific bond forms between a hematite (Fe 2 O 3 ) thin film, created with oxygen plasma-assisted molecular beam epitaxy, and recombinant MtrC or OmcA molecules coupled to gold substrates. Force spectra displayed a unique force signature indicative of a specific bond between each cytochrome and the hematite surface. The strength of the OmcA-hematite bond was approximately twice that of the MtrC-hematite bond, but direct binding to hematite was twice as favorable for MtrC. Reversible folding/unfolding reactions were observed for mechanically denatured MtrC molecules bound to hematite. The force measurements for the hematite-cytochrome pairs were compared to spectra collected for an iron oxide and S. oneidensis under anaerobic conditions. There is a strong correlation between the whole-cell and pure-protein force spectra, suggesting that the unique binding attributes of each cytochrome complement one another and allow both MtrC and OmcA to play a prominent role in the transfer of electrons to Fe(III) in minerals. Finally, by comparing the magnitudes of binding force for the whole-cell versus pure-protein data, we were able to estimate that a single bacterium of S. oneidensis (2 by 0.5 μm) expresses ∼10 4 cytochromes on its outer surface.

Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)zinc [Zn(TMHD)2] is a relatively uninvestigated precursor that was used in this work to grow highly c-axis-oriented ZnO films on Si(100). X-ray photoelectron spectroscopy studies before and after Ar ion sputtering indicated that surface carbon on several samples was reduced from as much as 34 at.% to much less than 1 at.% within the first 5 nm, indicating very clean Zn(TMHD)2 precursor decomposition. Microstructural and compositional analysis revealed columnar ZnO grains with domain widths of approximately half the total film thickness and a Zn-to-O atomic percent ratio indicative of stoichometric ZnO.

Nanoporous, high-surface area films of TiO2 are synthesized by reactive ballistic deposition of titanium metal in an oxygen ambient. Auger electron spectroscopy (AES) is used to investigate the stoichiometric dependence of the films on growth conditions (surface temperature and partial pressure of oxygen). Scanning and transmission electron microscopies show that the films consist of arrays of separated filaments. The surface area and the distribution of binding site energies of the films are measured as functions of growth temperature, deposition angle, and annealing conditions using temperature programmed desorption (TPD) of N2. TiO2 films deposited at 50 K at 70° from substrate normal display the greatest specific surface area of ∼100 m2/g. In addition, the films retain greater than 70% of their original surface area after annealing to 600 K. The combination of high surface area and thermal stability suggests that these films could serve as supports for applications in heterogeneous catalysis.

We have explored the systematics of TiO2 polymorph nucleation during film growth by molecular beam epitaxy on perovskite substrates. The accidental lattice match between anatase (0 0 1) and LaAlO3(0 0 1) or SrTiO3(0 0 1) typically results in anatase nucleation at the interface. However, the growth conditions dictate whether or not rutile also nucleates, and the associated morphological and structural properties of the composite film. Four symmetry equivalent epitaxial orientations of rutile on anatase are observed when rutile nucleates as discrete particles on LaAlO3(0 0 1). Such films constitute model systems for studying the anatase/rutile interface, which is of considerable current interest in photochemistry.

In this work alpha-Cr(2)O(3)/alpha-Fe(2)O(3) core-shell polycrystalline nanostructures were synthesized by using alpha-Cr(2)O(3) nanoparticles as seed crystals during aqueous nucleation. The formation of alpha-Fe(2)O(3) polycrystallites on alpha-Cr(2)O(3) surfaces was confirmed by X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray analysis. The excited-state relaxation dynamics of as-grown core-shell structures and "pure" alpha-Fe(2)O(3) particles of the same size were measured with femtosecond transient absorption spectroscopy. The results show the carrier lifetimes decay within a few picoseconds regardless of sample. This is likely due to fast recombination/trapping of carriers to defects and iron d-states.

Cobalt silicide has emerged as a leading contact material in silicon technology due to its low resistivity, high stability and small lattice mismatch. In this study, 0.2-0.4 mu m thick Co films were deposited on Si(100) wafers by RF magnetron sputtering at room temperature, and annealed at temperatures from 600 to 900 degrees C in vacuum. As-deposited and annealed samples were characterized by Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Although the Si substrates were sputter cleaned before the deposition, all the samples showed a thin oxide layer at the Si/Co interfaces. Annealing up to 700 degrees C did not alter the composition at the interface except small amount Co diffusion into Si. Annealing at 800 degrees C promotes the evaporation of the oxides from the interface and, as a result, clean CoSi2 films were formed. Although the interface appeared to be sharp within the RBS resolution after high temperature annealing, the surface topography was relatively rough with varying size of crystal grains. (c) 2006 Elsevier B.V. All rights reserved. (Less)

Electronic energy loss of charged particles in materials is a fundamental process accountable for the unique response of materials in applications of advanced nuclear power, radiation detectors, and advanced processing of electronic devices. For over a century, the stopping of energetic ions in matter has been a subject of great experimental and theoretical interest. In spite of a long history of studies, the electronic stopping force is not adequately described over all ranges of ions, energies and targets, particularly in the case of heavy ions in compound targets. In this study, stopping powers for ions in ceramic oxides of SiO2, ZrO2, Ta2O5 and Nb2O5 have been determined using a time-of-flight energy elastic recoil detection analysis (ToF-E ERDA) set-up. In transmission geometry, the energy loss of heavy ions in the thin foils was measured over a continuous range of energies from a few 10 keV/nucleon to over a thousand keV/nucleon using the ToF data that was tagged by a Si detector with and without the stopping foils. Comparisons are made with the SRIM-2003 (The Stopping and Range of Ions in Matter) predictions, and deviations are discussed.

Gdolinia doped ZrO2 and CeO2 multi-layer films were deposited on α-Al2O3 (0001) using oxygen-plasma-assisted molecular-beam epitaxy. Oxygen vacancies and Gd dopant distributions were investigated in these multi-layer films using X-ray diffraction (XRD), conventional and high-resolution transmission electron microscopy (HRTEM), annular dark-field imaging in scanning transmission electron microscopy (STEM), X-ray energy dispersive spectroscopy (EDS) elemental mapping and X-ray photoelectron spectroscopy (XPS) depth profiling. EDS and XPS depth profiling reveal that the Gd concentration in the ZrO2 layer is lower than that in the CeO2 layer. As a result, a higher oxygen vacancy concentration exists in the CeO2 layers compared to that in the ZrO2 layers. In addition, Gd is found to segregate only at the interfaces formed during the deposition of CeO2 layers on ZrO2 layers. On the other hand, the interfaces formed during the deposition of ZrO2 layers on CeO2 layers did not show any Gd segregation. The Gd segregation behavior at every other interface is believed to be associated with the low solubility of Gd in ZrO2.

The thermal reaction of Co film deposited on Si(111) surfaces by a high current filter metal vacuum arc (FMEVAD) system has been studied. After deposition the films were annealed over the 400-900 degrees C temperature range for 30 min. Rutherford backscattering spectrometry (RBS) was used to characterize the elemental depth distributions in the films subjected to different annealing temperatures. Ordered chemical phases were determined by glancing-incidence X-ray diffraction (GIXRD) and the morphology was determined by cross section transmission electron microscopy (TEM). The results show that the phases formed are Co2Si at 400 degrees C, CoSi + Coo at 500 degrees C, CoSi + CoSi2 at 600 degrees C and CoSi2 at (700-800 degrees C). At 900 degrees C, CiSi(2) was formed with a mixture of cubic cobalt and probably an amorphous cobalt oxide surface layer. The interface morphology was a rough cusp-like crenelation at 600 degrees C which became less pronounced after annealing at 800 degrees C. (c) 2006 Elsevier B.V. All rights reserved. (Less)

Na8(AlSiO4)6(ReO4)2 sodalite was synthesized using a hydrothermal method and its crystal structure was determined from Rietveld refinement of experimental X-ray powder diffraction data. The refinement showed that this compound adopts the cubic sodalite structure (space group P 4 ¯ 3 n , #218) with a = 9.1528 (1) A. Raman spectroscopic measurements confirm the presence of tetrahedral ReO 4 - groups. Broadening of the asymmetric stretching and bending vibrational modes suggests the tetrahedra are slightly distorted from ideal Td symmetry in the sodalite lattice. MAS NMR of 29Si and 27Al nuclei showed single intense peaks at δiso = −92.4 ppm and δiso = 57.5 ppm, respectively, confirming the alternating Si, Al tetrahedral ordering in sodalite deduced from the structural data. Chemical shifts for 29Si and 27Al calculated using correlative structural parameters (56.6 ± 0.8 ppm and −92.3 ± 0.9 ppm) showed good agreement with measured data indicating the validity of data derived from the Rietveld structural refinement.

Zn2SiO4:Mn2+, Zn2SiO4:Eu3+ and Zn2SiO4:Mn2+ Eu3+ phosphors were prepared by a sol-gel process and their luminescence spectra were investigated. The emission bands from intra-ion transitions of Mn2+ and Eu3+ samples were studied as a function of pressure. The pressure coefficient of Mn2+ emission was found to be -25.3 +/- 0.5 and -28.5 +/- 0.9 meV/GPa for Zn2SiO4:Mn2+ and Zn2SiO4:Mn2+ Eu3+, respectively. The Eu3+ emission shows only weak pressure dependence. The pressure dependences of the Mn2+ and Eu3+ emissions in Zn2SiO4:Mn2+ Eu3+ are slightly different from that in Zn2SiO4:Mn2+ and Zn2SiO4:Eu3+ samples, which can be attributed to the co-doping of Mn2+ and Eu3+ ions. The Mn2+ emission in the two samples, however, exhibits analogous temperature dependence and similar luminescence lifetimes, indicating no energy transfer from Mn2+ to Eu3+ occurs. (c) 2005 Elsevier B.V. All rights reserved.

Solid-state 29 Si, 27 Al, and 23 Na magic angle spinning (MAS) NMR techniques in combination with X-ray powder diffraction (XRD) are used to characterize aluminosilicate gels as a function of composition, pH, and reaction times. These gels were prepared at 80 °C using initial solutions with low Si/Al ratios, high alkaline and salt concentrations that are characteristic of nuclear tank wastes. XRD data show that cancrinite and sodalite are the main crystalline phases in the aluminosilicate gels produced. It is found that the pH and the salt content have significant effects on the nature of the aluminosilicate gels. Higher pH appears to increase the rate of crystallization, the degree of overall crystallinity and the percentage of cancrinite phases in aluminosilicate gels, whereas the high-salt concentration promotes the formation of cancrinite and sodalite and prohibits the formation of other zeolites. Complementary to XRD, NMR is extremely useful for providing the information on the structure of amorphous intermediate gels with no long-range order.

Efficient green emission from ZnMgS:Mn2+ nanoparticles prepared by co-doping Mg2+ and Mn2+ ions into ZnS lattices has been observed. The synthesis is carried out in aqueous solution, followed by a post-annealing process, thus showing the features of less complexity, low cost, and easy incorporation of dopants. In comparison with the emission of ZnS:Mn2+ nanoparticles, which is located generally around 590 nm, the photoluminescence of ZnMgS:Mn2+ nanoparticles is blue-shifted by 14 nm in wavelength, leading to the enhanced green emission. The X-ray diffraction, electron spin resonance, and pressure dependent photoluminescence measurements suggest that the change of the crystal field caused by Mg2+ ionic doping and the lower symmetry in the nanoparticles may account for the blue-shift of the photoluminescence. The ZnMgS:Mn2+ nanoparticles with 1% Mn2+ doping exhibit the strongest luminescence, which could potentially meet the requirements for the construction of green light emitting diodes.

The objectives of this study were to address uncertainties in the solubility product of (UO2)3(PO4)2⋅4H2O(c) and in the phosphate complexes of U(VI), and more importantly to develop needed thermodynamic data for the Pu(VI)-phosphate system in order to ascertain the extent to which U(VI) and Pu(VI) behave in an analogous fashion. Thus studies were conducted on (UO2)3(PO4)2⋅4H2O(c) and (PuO2)3(PO4)2⋅4H2O(am) solubilities for long-equilibration periods (up to 870 days) in a wide range of pH values (2.5 to 10.5) at fixed phosphate concentrations of 0.001 and 0.01 M, and in a range of phosphate concentrations (0.0001–1.0 M) at fixed pH values of about 3.5. A combination of techniques (XRD, DTA/TG, XAS, and thermodynamic analyses) was used to characterize the reaction products. The U(VI)-phosphate data for the most part agree closely with thermodynamic data presented in Guillaumont et al.,(1) although we cannot verify the existence of several U(VI) hydrolyses and phosphate species and we find the reported value for formation constant of UO2PO−4 is in error by more than two orders of magnitude. A comprehensive thermodynamic model for (PuO2)3(PO4)2⋅4H2O(am) solubility in the H+-Na+-OH−-Cl−-H2PO−4-HPO2−4-PO3−4-H2O system, previously unavailable, is presented and the data shows that the U(VI)-phosphate system is an excellent analog for the Pu(VI)-phosphate system.

Multi-layer films of pure ZrO{sub 2} and CeO{sub 2} were grown using oxygen plasma assisted molecular beam epitaxy on yttria stabilized zirconia (YSZ) substrates. The microstructure of the film was analyzed using x-ray diffraction (XRD), conventional and high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), energy dispersive x-ray (EDX) elemental mapping, selected area electron diffraction, and dynamical electron diffraction calculations. The deposited pure CeO{sub 2} layers exist in the cubic fluorite structure, and the ZrO{sub 2} layers show a good epitaxial orientation with respect to the CeO{sub 2} layers. However, distinctive forbidden diffraction spots of (odd, odd, even) type were observed on the selected area electron diffraction patterns of the film. Dark-field imaging clearly reveals that these forbidden diffraction spots were contributed solely by the ZrO{sub 2} layers. Dynamical electron diffraction calculation based on the tetragonal phase of unity tetragonality (space group P4{sub 2}/nmc) with oxygen displaced along the c-axis does not match with the experimental pattern. Instead, a diffraction pattern calculated based on a cubic structure (space group P{bar 4}3m) for which the oxygen sub-lattice was displaced along the matches with the experimental data. It is further suggested that the displacement of the oxygen from the idealmore » (1/4, 1/4, 1/4) position was introduced during the film growth process.« less

A ~1:1 mixture of ferrihydrite and nanocrystalline akaganeite (β-FeOOH; 10-15 nm) was incubated with Shewanella putrefaciens (strain CN32) under anoxic conditions with lactate as an electron donor and anthraquinone-2,6-disulfonate (AQDS) as an electron shuttle. The incubation was carried out in a 1,4-piperazinediethanesulfonic acid (PIPES)-buffered medium, without PO³⁻₄ at circumneutral pH. Iron reduction was measured as a function of time (as determined by 0.5 N HCl extraction), and solids were characterized by X-ray diffraction (XRD), electron microscopy, and Mossbauer spectroscopy. The biogenic reduction of Fe3+ was rapid; with 60% of the total Fe (Feтот) reduced in one day. Only an additional 10% of Feтот was reduced over the next three years. A fine-grained (10 nm), cation-excess (CE) magnetite with a Fe²⁺/Feтот ratio of 0.5-0.6 was the sole biogenic product after one day of incubation. The CE magnetite was unstable and partially transformed to micron-sized ferrous hydroxy carbonate [FHC; Fe₂ (OH)₂CO3(s)], a rosasite-type mineral, with time. Ferrous hydroxy carbonate dominated the mineral composition of the three year incubated sample. The Fe²⁺/Feтот ratio of the residual CE magnetite after three years of incubation was lower than the day 1 sample and was close to that of stochiometric magnetite (0.33). To best of ourmore » knowledge, this is the first report of biogenic FHC, and only the third observation of this material in nature. Ferrous hydroxy carbonate appeared to form by slow reaction of microbially produced carbonate with Fe²⁺-excess magnetite. The FHC may be an overlooked mineral phase that explains the infrequent occurrence of fine-grained, biogenic magnetite in anoxic sediments.« less

Single crystal 4H-SiC was irradiated with 2 MeV Au ions at 165 K. Ion-induced defect configurations and damage accumulation were studied by ion-channeling techniques along the , > < 3 40 4 and > < 1 20 2 directions. A nonlinear dependence of damage accumulation is observed for both the Si and C sublattices along all three directions, and the relative disorder observed along the > < 3 40 4 and > < 1 20 2 directions is much higher than that along the direction. The damage accumulation can be described by a disorder accumulation model, which indicates that defect-stimulated amorphization is the primary amorphization mechanism in SiC, and the high disorder level for the large off-axis angles is attributed to particular defect configurations. Molecular dynamics (MD) simulations demonstrate that most single interstitial configurations are shielded by Si and C atoms on the lattice sites along the direction, which significantly reduces their contribution to the backscattering/reaction yield along the direction.

Layer-by-layer epitaxial structures of gadolinia-doped ceria and zirconia have been synthesized on Al 2 O 3 (0001) using oxygen plasma-assisted molecular beam epitaxy. Increase in oxygen ion conductivity is observed with an increasing number of layers compared to bulk polycrystalline yttria-stabilized zirconia and gadolinia doped ceria electrolytes. The conductivity enhancement in these layered electrolytes is interesting, yet the exact cause for the enhancement remains unknown. For example, the space charge effects that are responsible for analogous conductivity increases in undoped layered halides are suppressed by the much shorter Debye screening length in layered oxides. Therefore, it appears that a combination of lattice strain and extended defects due to lattice mismatch between the heterogeneous structures may contribute to the enhancement of oxygen ionic conductivity in this layered oxide system.

A laboratory study performed on three waste streams with high metal content (between 20 and 60 wt%) showed that waste form durability was strongly influenced by processing conditions and waste form compositions. The study involved varying the waste loading, melting conditions, and heat treatment of a total of 15 waste forms. The normalized sodium release obtained from the product consistency test (PCT) was the main criterion used for durability comparisons between each waste form. It was found that a reducing melt condition had no effect on the durability of some waste forms, yet it decreased the durability of others up to 700% when compared to the oxidized melts. One waste form composition tested showed a 140% increase in durability when devitrified (crystallized) relative to its glassy form. Some compositions showed no change in durability after devitrification, while others showed a 200% decrease. Increased waste loading was also found to have varying effects dependent on the composition of the waste form and the processing atmosphere. These responses to processing and composition variations were dictated by fundamental glass chemistry and can be adjusted to achieve maximum waste loading, acceptable durability, and desirable processing characteristics with optimized formulations.

Both Nuclear reaction analysis and non-Rutherford elastic scattering have been widely used for analysis of light elements in solids; these two ion-beam methods complement more traditional analysis by Rutherford backscattering spectrometry. In this study, the reaction/scattering cross-sections for 12C(p,p)12C, 12C(d,p)13C, and 12C(a,a)12C at an angle of 150 (degrees) are measured over relevant energy regions using thin films of carbon (5.8 ug/cm2) on silicate glass. The results are plotted and tabulated as a function of ion energy, with typical uncertainties of 4% for the cross section data. In addition, the angular distribution of the cross sections for the reaction 12C(d,p)13C at an ion energy of 0.94 MeV has also been determined from 100 (degrees) to 170 (degrees). An example for the application of this reaction to SiC is given.

The growth of exchange-biased MnPd/Fe bilayers has been investigated using x-ray diffraction. The bilayers were deposited on MgO(001) substrates in an ultrahigh-vacuum ion-beam sputter system. It was found that the orientation of the MnPd unit cell and the crystalline quality could be controlled as a function of the deposition temperature. Twinned a-axis oriented MnPd films are obtained below 100 °C while single-crystalline c-axis films are obtained above 450 °C. Intermediate temperatures yield a mixture of both orientations with a poor crystalline quality. Moreover, the interface quality depends strongly on the deposition temperature and also the order in which MnPd and Fe are deposited. The results clearly show that interdiffusion is initiated at the Fe/MnPd interface at a lower temperature as compared to the MnPd/Fe interface. The close relationship between the structural and magnetic properties is also discussed.

Damage accumulation in Sm2Ti2O7 single crystals irradiated with Au2+ ions at 170, 300 and 700 K was studied by Rutherford backscattering spectrometry using a 2.0 MeV He+ beam along the 〈0 0 1〉 channeling direction. The relative disorder on the Sm sublattice follows a nonlinear dependence on ion fluence. The nonlinear behavior is described well by a disorder accumulation model that indicates a predominant role of a defect-stimulated amorphization process. The critical dose for amorphization at 300 K is ∼0.14 dpa, which is in good agreement with in situ transmission electron microscopy results for polycrystalline Sm2Ti2O7 irradiated with 600 keV Bi+ ions and with Gd2Ti2O7 doped with 244Cm. Despite the six orders of magnitude difference in damage rates, the good agreement between the amorphization doses in Sm2Ti2O7 at 300 K and 244Cm-doped Gd2Ti2O7 at 340 K indicates that damage accumulation at these temperatures is relatively independent of dose rate.

Multilayer films of pure ZrO2 and CeO2 were grown using molecular beam epitaxy on a yttria-stabilized zirconia (YSZ) substrate. Distinctive forbidden diffraction spots of (odd, odd, even) type were observed on the selected-area electron-diffraction patterns of the film. Dark-field imaging clearly revealed that these forbidden diffraction spots were solely due to the ZrO2 layers. Comparison of the electron diffraction pattern with that simulated by dynamical calculations suggest that the pure ZrO2 layers possess a cubic structure of space with the group P4 3m oxygen sublattice being displaced diagonally, rather than along the c axis as suggested for YSZ. Our results further suggest that the displacement of the oxygen from the ideal (¼, ¼, ¼) position might have been introduced during the film growth process.

Through the use of a metal catalyst, gasification of wet biomass can be accomplished with high levels of carbon conversion to gas at relatively low temperature (350 °C). In a pressurized-water environment (20 MPa), near-total conversion of the organic structure of biomass to gases has been achieved in the presence of a ruthenium metal catalyst. The process is essentially steam reforming, as there is no added oxidizer or reagent other than water. In addition, the gas produced is a medium heating value gas due to the synthesis of high levels of methane, as dictated by thermodynamic equilibrium. While good gas production was demonstrated, biomass trace components caused some processing difficulties in the fixed catalyst bed tubular reactor system used for the catalytic gasification process. Results are described for tests using both bench-scale and scaled-up reactor systems.

Using a thin amorphous layer of SiO 2 (5.2 μg/cm 2 ) on Si, cross sections for the nuclear reactions 16 O(d,p 1 ) 17 O, 16 O(d,α) 14 N and 16 O(α,α) 16 O at a laboratory angle of 150° are determined over energies ranging from 0.701 to 1.057 MeV for D + ions and from 2.949 to 3.049 MeV for He + ions. The results are plotted and tabulated as a function of ion energy, with typical uncertainties of 4% for the cross section data and of ±5 keV for the resonance energy. An example for the analysis of atomic displacements on the O sublattice in a Au 2+ -irradiated SrTiO 3 single crystal is given.

Cubic-CeO 2 and α-Fe 2 O 3 thin films have been epitaxially grown on yttria-stabilized ZrO 2 and α-Al 2 O 3 substrates, respectively, by oxygen plasma assisted molecular beam epitaxy. The interface structural features between the films and the substrates were characterized by Rutherford backscattering spectrometry (RBS), high resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). RBS channeling spectra for both CeO 2 /ZrO 2 and Fe 2 O 3 /Al 2 O 3 show interface disorder-related scattering peaks. It is believed that the observed interface disorder-related scattering peaks in the RBS spectra are due to interface misfit dislocations. Cross sectional HRTEM reveals that interfaces of both systems are similarly characterized by coherent regions that are separated by misfit dislocations periodically distributed along the interface. The experimentally observed dislocation spacings are approximately consistent with those calculated from the lattice mismatch, implying that the lattice mismatch is accommodated mainly by interface misfit dislocations.

Internal motions of d-ribose selectively 2H-labeled at the 2′ position were measured using solid state 2H NMR experiments. A sample of d-ribose-2′-d was prepared in a hydrated, non-crystalline state to eliminate effects of crystal-packing. Between temperatures of −74 and −60 °C the C2′–H2′ bond was observed to undergo two kinds of motions which were similar to those of C2′–H2′/H2′′ found previously in crystalline deoxythymidine (Hiyama et al. (1989) J. Am. Chem. Soc., 111, 8609–8613): (1) Nanosecond motion of small angular displacement with an apparent activation energy of 3.6 ± 0.7 kcal mol−1, and (2) millisecond to microsecond motion of large amplitude with an apparent activation energy ≥4 kcal mol−1. At −74 °C, the slow, large-amplitude motion was best characterized as a two-site jump with a correlation time on the millisecond time scale, whereas at −60 °C it was diffusive on the microsecond time scale. The slow, large-amplitude motions of the C2′–H2′ bond are most likely from interconversions between C2′-endo and C3′-endo by way of the O4′-endo conformation, whereas the fast, small-amplitude motions are probably librations of the C2′–H2′ bond within the C2′-endo and C3′-endo potential energy minima.

The Formation of Strontium Silicates at Low Temperature and the Solubility Product of Tobermorite like Sr5Si6O16(OH)2 5H20

We describe here studies aimed at the identification of optimum parameters for the epitaxial growth of the mixed-oxide films, Ce 1− x Zr x O 2 with x =0.1, 0.2 and 0.3, by oxygen-plasma-assisted MBE on single crystal Y-stabilized ZrO 2 (YSZ) substrates. The resulting films were characterized by RHEED, LEED, XPS/XPD, XRD, and RBS/C in order to determine their bulk and surface structures and compositions. Pure-phase, epitaxial Ce 1− x Zr x O 2 films readily grew on YSZ(111) without showing any contamination of yttria from the substrate. The resulting epitaxial film surfaces are unreconstructed and exhibit the structure of bulk CeO 2 (111). XPS data indicate that both Ce and Zr cations are formally in the +4 oxidation state for all films prepared here. Small differences in the photoemission results for Zr-doped ceria films as compared to those obtained for pure ZrO 2 may be explained by changes in electronic structure when Zr is added to ceria that, in turn, results from longer Zr–O bond distances in the mixed oxides. The minimum yields obtained from the random and channeling spectra of these films also provide evidence that high quality single crystal CeO 2 and Ce 0.7 Zr 0.3 O 2 materials were grown. For the Zr-doped films, Zr atoms are shown to occupy the lattice sites of Ce in the bulk structure of CeO 2 (111). Indeed, based on minimum yield values, the fraction of Zr substitution for Ce cations in the film was estimated to be 88%.

We have investigated the heteroepitaxial growth and materials properties of pure and Co-doped TiO2 anatase on SrTiO3(001) and LaAlO3(001), grown by oxygen plasma assisted molecular beam epitaxy. This material is a promising new diluted magnetic semiconductor that shows large magnetization and a Curie temperature well above room temperature. We have found that epitaxial films with the highest crystalline quality and most uniform distribution of Co result when a rather slow growth rate (∼0.01 nm/s) is used over a substrate temperature range of 550–600 °C on LaAlO3(001). These conditions result in layer-by-layer growth of single-crystal films and a very low density of extremely small nanocrystalline inclusions. In contrast, growth at a higher rate (∼0.04 nm/s) leads to extensive formation of secondary-phase rutile nanocrystals to which Co diffuses and segregates. The rutile nanocrystals nucleate on the evolving anatase film surface in such a way that lattice strain between the two phases is minimized. Cobalt appears to substitute for Ti in the lattice and exhibits a +2 formal oxidation state. Both pure and Co-doped films can be grown as n-type semiconductors by controlled incorporation of oxygen atom vacancies. Free electrons are required to couple the Co(II) spin to a ferromagnetic state.

SummaryThe solubility of synthetic becquerelite (Ca(UO2)6O4(OH)6·8H2O) was determined in 0.02, 0.1, and 0.5 M CaCl2solutions and at pCH+values ranging from approximately 4 to 11. The presence of becquerelite in equilibrated samples was confirmed by a combination of techniques involving X-ray diffraction, total chemical composition, and analyses of solubility data. The solubility data were interpreted using Pitzer's aqueous thermodynamic model and the thermodynamic data for U(VI) species available in the literature. The log of the solubility product for becquerelite [Ca(UO2)6O4(OH)6·8H2O + 14H+⇌ Ca2++ 6UO22++ 18H2O] was determined to be 41.4 ± 0.2. This value is similar to the values previously reported for other synthetic becquerelites, but is drastically different from a value reported for a natural sample.

The lean NO x performance and catalytic properties of In 2 O 3 /Al 2 O 3 catalysts were investigated. High lean NO x activity was observed when propene was used as a reductant in the presence of 9% O 2 and 7% H 2 O at a space velocity of 30,000 h −1 . The optimum lean NO x activity of In 2 O 3 /Al 2 O 3 catalysts was observed at a loading of 2.5 wt% indium on γ-Al 2 O 3 which was prepared by a sol–gel technique (230 m 2 /g). When propane was used as a reductant, the In 2 O 3 /Al 2 O 3 catalyst did not promote NO x reduction compared to the alumina substrate. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and temperature-programmed reduction (TPR) have been used to characterize a series of In 2 O 3 /Al 2 O 3 catalysts to increase understanding of the surface structure of indium oxide species on the alumina support. The XRD data indicated that crystalline In 2 O 3 was present at In 2 O 3 loadings >5 wt% and the quantity of the crystalline phase increased as a function of indium loading. XPS results suggested that indium oxide existed as a well-dispersed phase up to 10 wt% indium. The well-dispersed or reducible indium oxide species below 400°C in TPR experiments were assigned as the sites which activate propene to oxygenated hydrocarbons such as acetaldehyde and acrolein. Alumina sites readily utilize the oxygenated hydrocarbons to reduce NO x . A bifunction mechanism was proposed to explain high NO x reduction over In 2 O 3 /Al 2 O 3 catalysts.

α-Fe2O3(0001) films of thickness equal to ∼7 nm and ∼70 nm were epitaxially grown on α-Al2O3(0001) by oxygen plasma-assisted molecular beam epitaxy. The interfaces were characterized using high resolution transmission electron microscopy, electron energy-loss spectroscopy, and X-ray diffraction. The interface exhibited coherent regions separated by equally-spaced misfit dislocations. When imaged from the [2110] direction, the dislocation spacing is 7.0±1.1 nm for the 70-nm-thick specimen, and 7.2±0.1 nm for the 7-nm-thick specimen. When imaged from the [0110] direction, the dislocation spacing is 4.5±0.1 nm for the 7-nm-thick specimen. The experimentally observed dislocation spacings are approximately consistent with those calculated from the lattice mismatch between α-Al2O3 and α-Fe2O3, implying that the lattice mismatch is accommodated mainly by interface misfit dislocations above the critical thickness, which is less than 7 nm. This conclusion is also corroborated by the measured residual strain of ∼0.5% determined from X-ray diffraction for the 70 nm film. Electron-energy-loss-spectroscopy analysis reveals that the Fe L2,3-edge shows no measurable chemical shift relative to the L2,3-edge of structural Fe+3, indicating complete oxidation of Fe in the as-grown film.

The Gd2(Ti1-yZry)2O7 pyrochlore series undergoes a structural phase transition from pyrochlore (Fd3m) to defect fluorite (Fm3m) that can be driven compositionally by increasing the Zr content or thermally by sintering Zr-rich compositions at temperatures above 1550 °C. Our results demonstrate that ion-beam irradiation can also drive the structural phase transition for Zr-rich compositions. In an effort to understand the effects of composition and ion-beam irradiation on this phase transition, powder X-ray diffraction, polarized Raman, reflection infrared, and X-ray absorption spectroscopy experiments were conducted on Gd2(Ti1-yZry)2O7 pyrochlores prior to and following irradiation with 2 MeV Au2+ ions to a fluence of 5 ions/nm2. Analysis of the vibrational and X-ray absorption data suggests that the structural integrity of the pyrochlore structure is based on distorted corner-shared TiO6 or ZrO6 octahedra. The vibrational spectra indicate that both anion and cation disorder precede the compositionally d...

Highly porous (∼ 90%), high-surface area (∼1000 m2/g), thermally stable (1200 K) crystalline films of MgO are synthesized using a novel reactive ballistic deposition technique. The film consists of a tilted array of porous nanoscale crystalline filaments. Surprisingly, the individual filaments exhibit a high degree of crystallographic order with respect to each other. These films have chemical binding sites analogous to those on MgO(100). However, the fraction of chemically active, high energy binding sites is greatly enhanced on the nanoporous film. This unique collection of properties makes these materials attractive candidates for chemical applications such as sensors and heterogeneous catalysts.

This chapter is an overview of the book. It provides a general introduction to the book’s content and motivates some of the theoretical moves made there. As it says, the main theme is how judgements about reliability manifest in the semantics and pragmatics of natural language, focusing on the experiential basis for judging cooperativity and the likelihood that a given information source will give accurate information. It also gives a road map to reading the book, a brief statement of chapter dependencies, and a bit of background.