Synthesis and characterization of compositionally complex zirconate and phosphates

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Potential impacts of alternative fuels on the evolution and stability of turbine hot- section materials

This talk will provide an overview of a research program focused on evaluating the potential impacts of alternative fuels (coal-derived syngas, high-hydrogen content fuels, bio-derived synthetics) on the degradation of hot-section materials through accelerated attack of protective thermally grown oxides (TGOs) and thermal barrier coating (TBC) systems. A primary focus is the role of elevated water vapor levels, volatility, and vapor phase transport processes on the evolution of TGO and TBC systems. Materials exposure studies will be described that demonstrate that differing simulated combustion environments affect both the growth rate and the stability of the resulting thermally grown oxides. In systematic studies of oxide growth on MCrAlY bond coat materials in simulated combustion environments with varying pH2O, it is shown that the extent of spinel formation during transient oxidation is highly dependent upon the water vapor content in the exposure environment, and furthermore that the evolution of surface oxides is highly dependent upon volatilization and removal of spinel phases formed during transient oxidation periods. The pH2O dependence of spinel formation during transient oxidation, and evolution/removal during subsequent exposure to the simulated combustion environments, is found to be spatially-correlated with the underlying metal phase distributions, and hence is highly dependent upon the composition of the bond coat materials. These observations were verified by carrying out site-specific characterization of the growth and evolution of the surface spinels, with high-resolution imaging and characterization of the oxides that are formed (and spatially correlated with the initial microstructure). Observations of transient spinel volatilizing from TGO surfaces in high pH2O environments were supported by measurements of nickel volatilizing from pre-fabricated NiAl2O4 spinel pellets as a function of the simulated combustion environment. Additionally, this talk will discuss the role of high pH2O environments on TBC materials stability, as well as vapor-phase transport processes and mechanisms affecting TBC system lifetime

Factors affecting ceramic abradable coating damage accommodation

High temperature abradable coatings are based on thermal barrier coating compositions and play an integral role in not only providing thermal protection for turbine shrouds, but also in maintaining blade tip clearances for increased turbine efficiencies. As turbine material technologies advance, there is a push for the development of abradable coatings that can withstand more severe operating conditions and retain the optimum balance of abradability and durability. However, as abradable coating technologies are pushed to higher temperatures and greater capabilities, such as compatibility with ceramic matrix composites, there are significant challenges in understanding the underlying mechanisms that aid the design of these inherently brittle materials enabling them to accommodate damage in a controlled manner. This study will first discuss the theories for fracture mechanics and wear mechanisms in ceramics and how they can be related to abradable coatings. The influence of microstructural defects present in current technology ceramic abradable coatings on the preferred wear behavior of these systems will then be investigated. The coatings to be compared are air plasma sprayed dysprosia- or yttria- stabilized zirconia with varying fractions of pore former and secondary phases. The wear of both as-received and aged coatings will be tested, and deformation mechanisms will be reported. Links between different defects, their evolution with aging, and observed wear behavior will be compared with two competing definitions of desired abradable damage accommodation mechanisms, with one being energy dissipation through plastic deformation and the other depending on crack propagation and frictional sliding of the removed material to dissipate energy

On the CMAS Problem in Thermal Barrier Coatings%253A Benchmarking Thermochemical Resistance of Oxides Alternative to YSZ Through a Microscopic Standpoint

This study focuses on experimental modelling of the failure of Thermal Barrier Coatings (TBCs) due to attack of CMAS (Calcia-Magnesia-Alumina-Silicate), which is often found in harsh environments, via glassy phase infiltration. Volcanic ash and dust, sand particles, and fly ash, which contain CMAS, are imminent threats impeding predictable lifetimes of TBCs. Such incurrence directly affects the geometry and clinging to bond coat, and intrinsic material properties such as thermal conductivity and crystal structure of TBC are modified after exposure to CMAS, which ultimately results in delamination, spallation and failure of the coating material. The scope of this work is to survey the reactivity of CMAS with various oxide systems, and evaluate possible oxide systems that can be replaced and%252For used with Yttria-stabilized Zirconia (YSZ) by investigating the penetration depth and reactivity after sintering with CMAS. A cost-effective method to observe the reaction of candidate oxides with CMAS is suggested and administired%253B understanding the main mechanism that causes the failure of top coat in the wake of CMAS infiltration, and seeking solutions for the problem is performed by taking advantage of Scanning Electron Microscopy (SEM). Recently suggested ceramic oxide systems that form in pyrochlore structure, some perovskite structures in various compositions, monazite, mullite and YSZ are studied. The possible outcome consequent upon CMAS infiltration are concluded and course for designing novel material systems that are expected to withstand the CMAS attacks better than the state-of-the-art 4mole%25 YSZ is defined. 5%25 mole Yb-doped SrZrO3(5Yb-SZ) and favored pyrochlores such as Gd2r2O7 and GdYbZr2O7 are found to be better mitigating CMAS attacks

Microstructural evaluation with type i hot corrosion degradation of gas turbine alloys during burner-rig testing

The hot corrosion resistance of selected gas turbine alloys was evaluated, as a baseline for assessing candidate new hot-section materials. The alloys were tested under burner rig exposures, using ASTM standard seawater for the salt contaminant and combustion conditions that provide representative materials evolution and degradation behavior relative to what is observed with marine gas turbines under service environments. Modern characterization techniques were utilized to evaluate the hot corrosion behavior and resistance of the evaluated material systems, to observe the degradation of the alloys and to study the underlying degradation mechanisms active during hot corrosion attack. Please click Additional Files below to see the full abstract

Validation of the Human Activity Profile Questionnaire in Patients after Allogeneic Hematopoietic Stem Cell Transplantation

Chronic graft-versus-host disease (cGVHD) associated morbidity and mortality remain major barriers for successful allogeneic hematopoietic stem cell transplantation (alloHSCT). Currently, no reliable measures are established to monitor cGVHD activity changes for use in clinical trials. The Human Activity Profile (HAP) patient self-report was proposed by the National Institutes of Health (NIH) cGVHD consensus project as an independent measure of patients' functional status that could also indirectly reflect improvement of cGVHD, but that has not been validated in an alloHSCT patient population. One hundred seventy-six patients (median age 44 years [range: 18-72 years] after alloHSCT were evaluated with a German translation of the HAP, the NIH criteria-based cGVHD activity assessment, the Lee cGVHD Symptom-Scale, FACT-BMT, SF36, Berlin Social Support Scale, 24-Item Adjective Measure (24-AM), Hospital Anxiety and Depression Scale, and the NCCN-Distress-Thermometer. Enrollment occurred a median of 286 (range: 85-4003) days after alloHSCT. Follow-up surveys were conducted at 1, 2, 3, 5, 8, and 12 months after the baseline survey. Although 117 patient had cGVHD at time of enrollment (mild n = 33, moderate n = 50, or severe n = 34), 59 patients were included into the study in the absence of cGVHD between days 85 and 395 after transplantation. The maximum activity score (MAS) and adjusted activity score (AAS) of the HAP correlated inversely with grading of cGVHD severity (mild, moderate, or severe) (r = −0.25 for MAS and −0.24 for AAS). Lung manifestations of cGVHD correlated with AAS (r = 0.17), but not with MAS. HAP scores correlated with subscales from other instruments measuring physical domains, especially the physical functioning scale of the SF36. Performance was improved by use of an HSCT-modified HAP scoring system that excluded activities prohibited within the first year after alloHSCT. No significant correlation of the HAP was found with personality, age, sex, symptom burden, or social functioning or social well-being. Moreover, the HAP displayed a higher sensitivity to change of cGVHD activity compared to the SF36 and the FACT-BMT. In addition, steroid myopathy correlated with both HAP scores, but not the SF36. The HAP is a simple and valid questionnaire for the evaluation of the physical activity in patients after alloHSCT, with the advantage of detecting changes in cGVHD status independently of other quality-of-life measures and with a superior sensitivity compared to the SF36

Rapid adaptive optical recovery of optimal resolution over large volumes

Using a descanned, laser-induced guide star and direct wavefront sensing, we demonstrate adaptive correction of complex optical aberrations at high numerical aperture (NA) and a 14-ms update rate. This correction permits us to compensate for the rapid spatial variation in aberration often encountered in biological specimens and to recover diffraction-limited imaging over large volumes (>240 mm per side). We applied this to image fine neuronal processes and subcellular dynamics within the zebrafish brain

Characterization of the lying and rising sequence in lame and non-lame sows

peer-reviewedThis study aimed to identify possible differences in the lying and standing sequence between lame and non-lame gestating sows. A total of 85 stall-housed sows (average parity 0.9 ± 1.14; range 0–4) were scored for walking lameness on a 3-point scale (1 = normal to 3=severely lame) while moving to a separate gestation stall for recording of one lying-standing event on days 30, 60 and 90 of gestation. A video camera was positioned on the adjacent stall so sows’ profiles were visible. Observations ceased when the sow laid-down and stood-up, or 2.5 h elapsed from recording commencement. From videos, postures and movements that occurred during lying-standing sequences were identified. Time (seconds) from kneeling to shoulder rotation (KSR), shoulder rotation to lying (SRHQ), total time to lie (TLIE); latency to lie (LATENCY; minutes) and number of attempts to successfully lie were recorded. Also, time taken from first leg fold to sit (TLS), time from sit to rise (TSR), and total time to rise (TRISE) were recorded. Sows were re-classified as non-lame (score 1) and lame (scores ≥ 2). Data were analyzed using mixed model methods with gestation day, and lameness as fixed effects and sow the random effect. On average, sows took 14.3 ± 1.39 s for KSR, 7.7 ± 0.79 s for SRHQ, 21.0 ± 1.37 s for TLIE and 63.6 ± 5.97 min for LATENCY. Furthermore, sows took 8.8 ± 2.80 s for TLS, 5.95 ± 1.73 s for TSR, and 10.3 ± 2.02 s for TRISE. There were no associations between lameness status or gestation day with time required for or the likelihood of performing the different movements of the lying and standing sequences (P >  0.05). Except for lame sows tending to sit more while transitioning from lying to standing than non-lame sows (P =  0.09). Seven different lying and 4 different standing combination deviation from the normal sequences, albeit each combination was infrequent and did not allow for statistical analysis. However, all together, deviations from the normal lying and standing sequence accounted for 22.7 % and 35 % of total observations; respectively. Under the conditions of this study, lameness did not influence the time taken or the likelihood of performing different movements and/or postures during normal lying-standing sequences. However, this could be due to lameness recorded here not being severe enough to affect the sequences. The observed deviations suggest that there is variation in the way sows lie and stand although more research is necessary to understand which factors contribute to such variation.National Pork Boar

Volatile Analysis by Pyrolysis of Regolith for Planetary Resource Exploration

The extraction and identification of volatile resources that could be utilized by humans including water, oxygen, noble gases, and hydrocarbons on the Moon, Mars, and small planetary bodies will be critical for future long-term human exploration of these objects. Vacuum pyrolysis at elevated temperatures has been shown to be an efficient way to release volatiles trapped inside solid samples. In order to maximize the extraction of volatiles, including oxygen and noble gases from the breakdown of minerals, a pyrolysis temperature of 1400 C or higher is required, which greatly exceeds the maximum temperatures of current state-of-the-art flight pyrolysis instruments. Here we report on the recent optimization and field testing results of a high temperature pyrolysis oven and sample manipulation system coupled to a mass spectrometer instrument called Volatile Analysis by Pyrolysis of Regolith (VAPoR). VAPoR is capable of heating solid samples under vacuum to temperatures above 1300 C and determining the composition of volatiles released as a function of temperature