Science.gov

Sample records for adherent alumina scales

  1. The mechanical reliability of alumina scales and coatings

    SciTech Connect

    Alexander, K.B.; Pruebner, K.; Tortorelli, P.F.

    1996-08-01

    The mechanical integrity of oxide scales ultimately determines their ability to protect materials from corrosion and other environmental effects arising from deleterious reactions with gases and condensable products. The microstructure and mechanical behavior of alumina products thermally grown or deposited on Fe-28 at.% Al intermetallic alloys are being characterized in order to develop the knowledge and means to control the mechanical reliability of alumina scales by microstructural manipulation through design and processing. Mechanical characterization involved gravimetric data from cyclic oxidation experiments, in-situ observation of oxidized specimens undergoing flexural loading in a scanning electron microscope, and measurements of hardness, elastic modulus and cracking resistance by nanoindentation. Values of cracking thresholds for Al{sub 2}O{sub 3} scales were consistent with other measurements for surface and bulk alumina. The oxidation behavior of Fe{sub 3}Al alloys coated with a thin (0.5 - 1 {mu}m) alumina film deposited by plasma synthesis has been studied. During exposure in the oxidizing environment, new oxide was formed between the coating and the substrate. The presence of the deposited amorphous oxide inhibited the subsequent thermal oxidation of the metal. Because the thermally grown alumina forms under the deposit, the adherence of the coating is controlled by the strength of the metal/oxide interface that develops during oxidation.

  2. Moisture-Induced Alumina Scale Spallation: The Hydrogen Factor

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2009-01-01

    For some time our community has been concerned with interfacial spallation of protective alumina scales, not just upon immediate cooldown, but as a time-delayed phenomenon. Moisture-induced delayed spallation (MIDS) and desktop spallation (DTS) of TBC's refer to this process. It is most apparent for relatively adherent alumina scales that have survived cool down in a dry environment, built up considerable thickness and strain energy, and have been somewhat damaged, such as by cyclic oxidation cracking. Indeed, a "sweet zone" can be defined that maximizes the observed effect as a function of all the relevant factors. Moisture has been postulated to serve as a source of interfacial hydrogen embrittlement derived from reaction with aluminum in the alloy at an exposed interface. The purpose of this monograph is to trace the close analogy of this phenomenon to other hydrogen effects, such as embrittlement of aluminides and blistering of alloys and anodic alumina films. A formalized, top-down, logic tree structure is presented as a guide to this discussion. A theoretical basis for interfacial weakening by hydrogen is first cited, as are demonstrations of hydrogen as a reaction product or detected interfacial species. Further support is provided by critical experiments that produce the same moisture effect, but by isolating hydrogen from other potential causative factors. These experiments include tests in H2-containing atmospheres or cathodic hydrogen charging.

  3. Moisture-Induced Alumina Scale Spallation: The Hydrogen Factor

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2010-01-01

    For some time the oxidation community has been concerned with interfacial spallation of protective alumina scales, not just upon immediate cool down, but as a time-delayed phenomenon. Moisture-induced delayed spallation (MIDS) and desktop spallation (DTS) of thermal barrier coatings (TBCs) refer to this process. It is most apparent for relatively adherent alumina scales that have survived initial cool down in a dry environment, have built up considerable thickness and strain energy, and have been somewhat damaged, such as by cyclic oxidation cracking. Indeed, a "sensitive zone" can be described that maximizes the observed effect as a function of all the relevant factors. Moisture has been postulated to serve as a source of interfacial hydrogen embrittlement. Hydrogen is derived from reaction with aluminum in the alloy at an exposed interface. The purpose of this monograph is to trace the close analogy of this phenomenon to other hydrogen-induced effects, such as embrittlement of aluminides and blistering of alloys and anodic alumina films. A formalized, top-down, logic-tree structure is presented as a guide to this discussion. A theoretical basis for interfacial weakening by hydrogen is first cited, as are demonstrations of hydrogen detection as a reaction product or interfacial species. Further support is provided by critical experiments that recreate the moisture effect, but by isolating hydrogen from other potential causative factors. These experiments include tests in H 2-containing atmospheres or cathodic hydrogen charging. Accordingly, they strongly indicate that interfacial hydrogen, derived from moisture, is the key chemical species accounting for delayed alumina scale spallation.

  4. The microstructure and mechanical reliability of alumina scales and coatings

    SciTech Connect

    Alexander, K.B.; Pruessner, K.; Tortorelli, P.F.

    1997-09-01

    Alumina scales on iron-aluminides (Fe{sub 3}Al-based) and NiCrAl- based alloys were characterized in order to develop the knowledge to control the oxidation performance of alloys by controlling the microstructure and microchemistry of their scales. Plasma-deposited amorphous alumina coatings on iron-aluminides were used to study phase transformations, transport processes in the scales, and S segregation to the scale/metal interface. It was found that during heat treatment in absence of oxidation, amorphous coatings first transform to {gamma}-Al{sub 2}O{sub 3} and eventually {alpha}-Al{sub 2}O{sub 3} nucleates at the scale/metal interface. Sulfur from the Zr- free alloy segregates to the scale/metal interface during heat treatment. Thermally grown scales on Zr-doped iron-aluminides were compared to those formed after oxidation of a specimen with an alumina coating. Microstructural and gravimetric results showed that the primarily amorphous alumina coating promoted the nucleation and growth of metastable alumina phases, which resulted in more rapid oxidation. The thermally grown oxide was found on top of the coating. The NiCrAl-based alloys formed columnar alumina scales underneath a layer of mixed oxides. Segregation of alloying elements like Y, Hf, and At was found at both oxide grain boundaries and scale/metal interfaces.

  5. Sulfur and Moisture Effects on Alumina Scale and TBC Spallation

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2007-01-01

    cause is related to a hydrogen embrittlement reaction: Al alloy + 3 H2O = Al(OH)3 + 3H(+) + 3e(-). This mechanism is derived from an analogous moisture-induced hydrogen embrittlement mechanism originally shown for Ni3Al and FeAl intermetallics. Consequently, a cathodic hydrogen charging technique was used to demonstrate that electrolytic de-scaling occurs for these otherwise adherent alumina scales formed on Y-doped Rene'N5, in support of hydrogen effects. Finally, some TBC observations are discussed in light of all of the above. Plasma sprayed 8YSZ coatings, produced on PWA1484 without a bond coat, were found to survive more than 1000 1-hr cycles at 1100 C when desulfurized to below 0.1 ppmw. At higher sulfur (1.2 ppmw) levels, moisture sensitivity and delayed TBC failure, referred to as Desk Top Spallation, occurred at just 200 hr. Despite a large degree of scatter, a factor of 5 in life improvement is indicated for desulfurized samples in cyclic furnace tests, confirming the beneficial effect of low sulfur alloys on model TBC systems. (DTS and moisture effects are also observed on commercially applied PVD 7YSZ coatings on Rene'N5+Y with Pt-aluminide bond coats). These types of catastrophic failure were subverted on the model system by segmenting the substrate into a network of 0.010 high ribs, spaced in. apart, prior to plasma spraying. No failures occurred after 1000 cycles at 1150 C or after 2000 cycles at 1100 C, even after water immersion. The benefit is described in terms of elasticity models and a critical buckling stress.

  6. Dopant effect of yttrium and the growth and adherence of alumina on nickel-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Anderson, A. B.; Mehandru, S. P.; Smialek, J. L.

    1985-01-01

    The atom superposition and electron delocalization molecular orbital theory and large cluster models have been employed to study cation vacancy diffusion in alpha-Al2O3 and the bonding of alpha-Al2O3 to nickel, aluminum, and yttrium surfaces. Al(3+) diffusion barriers in alpha-Al2O3 by the vacancy mechanism are in reasonable agreement with experiment. The barrier to Y(3+) diffusion is predicted to be much higher. Since addition of yttrium to transition metal alloys is known to reduce the growth rate and stress convolutions in protective alumina scales, this result suggests the rate-limiting step in scale growth is cation vacancy diffusion. This may partially explain the beneficial effect of yttrium dopants on scale adhesion. The theory also predicts a very strong bonding between alumina and yttrium at the surface of the alloy. This may also be important to the adhesion phenomenon. It is also found that aluminum and yttrium atoms bond very strongly to nickel because of charge transfer from their higher lying valence orbitals to the lower lying nickel s-d band.

  7. Microstructural and mechanical characterization of alumina scales thermally developed on iron aluminide alloys

    SciTech Connect

    Natesan, K.; Renusch, D.; Veal, B.W.; Grimsditch, M.

    1996-11-01

    To understand the underlying phenomena when characterizing material performance, we must know the chemistry and physics of the early stages of oxidation, chemistry, and bonding at the substrate/oxide interface, effect of segregants on the strength of bonding, transport processes through the scale formed during corrosion, mechanisms of residual stress generation and relief, and fracture behavior at the oxide/substrate interface. Specific objectives of the program described here are to (a) systematically investigate the relationships among substrate composition and properties and scale/coating adherence, damage tolerance, and micromechanical properties; (b) use results from the investigation to prevent scale/coating failure at elevated temperatures; and (c) identify conditions that lead to coatings that are more damage tolerant and scales that are amenable to legitimate synthesis routes. This report presents experimental data on the microstructural characteristics of alumina scales that have been thermally developed on several Fe-based alumina-forming intermetallic alloys. In addition, data are presented on scale adhesion, along with determinations of strain from data obtained by ruby fluorescence.

  8. Conduction in alumina with atomic scale copper filaments

    SciTech Connect

    Xu, Xu; Liu, Jie; Anantram, M. P.

    2014-10-28

    The conductance of atomic scale filaments with three and seven Cu atoms in α-alumina are calculated using ab initio density functional theory. We find that the filament with 3 Cu atoms is sufficient to increase the conductance of 1.3 nm thick alumina film by more than 10{sup 3} times in linear response. As the applied voltage increases, the current quickly saturates and differential resistance becomes negative. Compared to the filament with three Cu atoms, while the conductance of the filament with seven Cu atoms is comparable in linear response, they carry as much as twenty times larger current at large biases. The electron transport is analyzed based on local density of states, and the negative differential resistance in the seven Cu filaments occurs due to their narrow bandwidth.

  9. Transient improvement of urticaria induces poor adherence as assessed by Morisky Medication Adherence Scale-8.

    PubMed

    Kaneko, Sakae; Masuda, Koji; Hiragun, Takaaki; Inomata, Naoko; Furue, Masutaka; Onozuka, Daisuke; Takeuchi, Satoshi; Murota, Hiroyuki; Sugaya, Makoto; Saeki, Hidehisa; Shintani, Yoichi; Tsunemi, Yuichiro; Abe, Shinya; Kobayashi, Miwa; Kitami, Yuki; Tanioka, Miki; Imafuku, Shinichi; Abe, Masatoshi; Hagihara, Akihito; Morisky, Donald E; Katoh, Norito

    2015-11-01

    Poor adherence to medication is a major public health challenge. Here, we aimed to determine the adherence to oral and topical medications and to analyze underlying associated factors using the translated Japanese version of Morisky Medication Adherence Scale-8 regarding urticaria treatment. Web-based questionnaires were performed for 3096 registered dermatological patients, along with a subanalysis of 751 registered urticaria patients in this study. The adherence to oral medication was significantly associated with the frequency of hospital visits. Variables that affected the adherence to topical medication included age and experience of drug effectiveness. The rate of responses that "It felt like the symptoms had improved" varied significantly among the dermatological diseases treated with oral medications. Dermatologists should be aware that adherence to the treatment of urticaria is quite low. Regular visits and active education for patients with urticaria are mandatory in order to achieve a good therapeutic outcome by increasing the adherence.

  10. Detection of Low Adherence in Rural Tuberculosis Patients in China: Application of Morisky Medication Adherence Scale

    PubMed Central

    Xu, Minlan; Markström, Urban; Lyu, Juncheng; Xu, Lingzhong

    2017-01-01

    The detection and analysis of cases of low medication adherence is important for helping to control tuberculosis (TB). The purpose of this study was to detect low adherence in rural TB patients by using the eight-item Morisky Medication Adherence Scale of Chinese version (C-MMAS-8) and to further analyze the adherence-related variables. A total of 358 rural TB patients recruited through multi-stage randomized sampling participated in the survey. Data were collected by the use of interviewer-led questionnaires. First, the reliability and validity of the C-MMAS-8 were determined. Second, the adherence level was assessed, and factors related to low adherence were analyzed by using Pearson’s chi-square test and then in multiple logistic regression model. Finally, the prediction of the logistic model was assessed with Receiver Operating Characteristic (ROC) curves. The C-MMAS-8 could be used to detect low adherence in TB patients with good reliability and validity. By using the referred cutoff points of MMAS-8, it was found that more than one-third of the participants had low medication adherence. Further analysis revealed the variables of being older, a longer treatment time, and being depressive were significantly related to low adherence. The ROC of the model was assessed as good using the cutoff point. We conclude that appropriately tailored strategies are needed for health-care providers to help rural TB patients cope with low medication adherence. PMID:28257075

  11. Delayed Alumina Scale Spallation on Rene'n5+y: Moisture Effects and Acoustic Emission

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Morscher, Gregory N.

    2001-01-01

    The single crystal superalloy Rene'N5 (with or without Y-doping and hydrogen annealing) was cyclically oxidized at 1150 C for 1000 hours. After considerable scale growth (>= 500 hours), even the adherent alumina scales formed on Y-doped samples exhibited delayed interfacial spallation during subsequent water immersion tests, performed up to one year after oxidation. Spallation was characterized by weight loss, the amount of spalled area, and acoustic emission response. Hydrogen annealing (prior to oxidation) reduced spallation both before and after immersion, but without measurably reducing the bulk sulfur content of the Y-doped alloys. The duration and frequency of sequential, co-located acoustic emission events implied an interfacial crack growth rate at least 10(exp -3) m/s, but possibly higher than 10(exp 2) m/s. This is much greater than classic moisture-assisted slow crack growth rates in bulk alumina (10(exp -6) to 10(exp -3) m/s), which may still have occurred undetected by acoustic emission. An alternative failure sequence is proposed: an incubation process for preferential moisture ingress leads to a local decrease in interfacial toughness, thus allowing fast fracture driven by stored strain energy.

  12. Chemical and microstructural characterization of thermally grown alumina scales

    SciTech Connect

    Natesan, K.; Richier, C.; Veal, B.W.

    1995-09-01

    An experimental program has been initiated to evaluate the chemical, microstructural, and mechanical integrity of thermally grown oxide scales to establish requirements for improved corrosion performance in terms of composition, structure, and properties. Iron aluminides of several compositions were selected for the study. Oxidation studies were conducted in air and oxygen environments at 1000{degrees}C. The results showed that the scaling kinetics followed a parabolic rate law but that the rates in early stages of oxidation were significantly greater than in later stages; the difference could be attributed to the presence of fast-growing transient iron oxides in the layer during the early stages. Further, scale failure occurred via gross spallation, scale cracking, and nodule formation and was influenced by alloy composition. Auger electron spectroscopy of Ar-exposed specimens of ternary Fe-Cr-Al alloy showed sulfur on the gas/scale side of the interface; the sulfur decreased as the exposure time increased. Raman spectroscopy and ruby fluorescence were used to examine the scale development as a function of oxidation temperature. Ruby-line shift is used to examine phase transformations in alumina and to calculate compressive strains in thermally grown scales.

  13. Corrosion performance of alumina scales in coal gasification environments

    SciTech Connect

    Natesan, K.

    1997-02-01

    Corrosion of metallic structural materials in complex gas environments of coal gasification is a potential problem. The corrosion process is dictated by concentrations of two key constituents: sulfur as H{sub 2}S and Cl as HCl. This paper examines the corrosion performance of alumina scales that are thermally grown on Fe-base alloys during exposure to O/S mixed-gas environments. The results are compared with the performance of chromia-forming alloys in similar environments. The paper also discusses the available information on corrosion performance of alloys whose surfaces were enriched with Al by the pack-diffusion process, by the electrospark deposition process, or by weld overlay techniques.

  14. Lightweight alumina refractory aggregate. Phase 2, Pilot scale development

    SciTech Connect

    Swansiger, T.G.; Pearson, A.

    1994-11-01

    Kilogram quantities of refractory aggregate were prepared from both a paste and a pelletized form of extruder feed material in both bench and pilot-scale equipment. The 99{sup +} % alumina aggregate exhibited a bulk density approaching 2.5 g/cm{sup 3} and a fired strength slightly lower than fused alumina. Based on initial evaluation by two refractory manufacturers in brick or castable applications, the new aggregate offered adequate strength with thermal conductivity reductions up to 34%, depending on the temperature and application of the new aggregate in these initial trials. The new aggregate was simply substituted for Tabular{trademark} in the refractory formulation. Thus, there is room for improvement through formulation optimization with the lightweight aggregate. The new aggregate offers a unique combination of density, strength, and thermal properties not available in current aggregate. To this point in time, technical development has led to a pelletized formulation with borderline physical form leaving the Eirich mixer. The formulation requires further development to provide more latitude for the production of pelletized material without forming paste, while still reducing the bulk density slightly to reach the 2.5 g/cm{sup 3} target. The preferred, pelletized process flowsheet was outlined and a preliminary economic feasibility study performed based on a process retrofit into Alcoa`s Arkansas tabular production facilities. Based on an assumed market demand of 20,000 mt/year and an assumed selling price of $0.65/lb (25% more than the current selling price of Tabular{trademark}, on a volume basis), economics were favorable. Decision on whether to proceed into Phase 3 (full- scale demonstration) will be based on a formal market survey in 1994 October.

  15. Sulfur Impurities and the Microstructure of Alumina Scales

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    1997-01-01

    The relationship between the microstructure of alumina scales, adhesion, and sulfur content was examined through a series of nickel alloys oxidized in 1100 to 1200 deg. C cyclic or isothermal exposures in air. In cyclic tests of undoped NiCrAl, adhesion was produced when the sulfur content was reduced, without any change in scale microstructure. Although interfacial voids were not observed in cyclic tests of NiCrAl, they were promoted by long-term isothermal exposures, by sulfur doping, and in most exposures of NiAl. Two single crystal superalloys, PWA 1480 and Rene' N5, were also tested, either in the as-received condition or after the sulfur content had been reduced to less than 1 ppmw by hydrogen annealing. The unannealed alloys always exhibited spalling to bare metal, but interfacial voids were not observed consistently. Desulfurized PWA 1480 and Rene' N5 exhibited remarkable adhesion and no voidage for either isothermal or cyclic exposures. The most consistent microstructural feature was that, for the cases where voids did form, the scale undersides exhibited corresponding areas with ridged oxide grain boundaries. Voids were not required for spallation nor were other microstructural features essential for adhesion. These observations are consistent with the model whereby scale spallation is controlled primarily by interfacial sulfur segregation and the consequent degradation of oxide-metal bonding.

  16. The mechanical reliability of alumina scales and coatings

    SciTech Connect

    Alexander, K.B.; Pruebner, K.; Tortorelli, P.F.

    1996-06-01

    In many high-temperature fossil energy systems, corrosion and deleterious reactions with gases and condensable products in the operating environment often compromise materials performance. The presence of a stable surface oxide (either as thermally-grown scales or deposited coatings) can effectively protect the materials from these reactions if the oxides are slow-growing, dense and adherent to the substrate. The protection these brittle oxide films provide has long been a critical issue, particularly for applications involving severe high-temperature thermal cycles or very aggressive (for example, sulfidizing) environments. The various factors which control the scale/coating integrity and adherence are not well understood. The present multilaboratory collaborative work is intended to define the relationships between substrate characteristics (composition, microstructure, and mechanical behavior) and the structure and protective properties of deposited oxide coatings and/or thermally grown scales. Through such studies, the ultimate goal is to assure environmental protection through effective processing and materials selection leading to the development of corrosion-resistant, high-temperature materials for improved energy and environmental control systems.

  17. Diffusivity in Alumina Scales Grown on Al-MAX Phases

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2014-01-01

    Ti3AlC2, Ti2AlC, and Cr2AlC are oxidation resistant MAX phase compounds distinguished by the formation of protective Al2O3 scales with well controlled kinetics. A modified Wagner treatment was used to obtain interfacial grain boundary diffusivity, deltaD(sub gb,O,int.), from scale growth rates and corresponding grain size. It is based on the p(O2)(exp -1/6) dependency of the double charged oxygen vacancy and oxygen diffusivity, coupled with the effective diffusion constant for short circuit grain boundary paths. Data from the literature for MAX phases was analyzed accordingly, and deltaD(sub gb,O,int.) was found to nearly coincide with the Arrhenius line developed for Zr-doped FeCrAl, where: deltaD(sub gb,O,int.) = 1.8x10(exp -10) exp(-375 kJ/RT) cubic meters/s. Furthermore, this oxidation relation suggests the more general format applicable to bulk samples under ambient conditions: deltaD(sub gb,O) = 7.567x10(exp -8) exp(-544 kJ/RT) p(O2)(exp -1/6) cubic meters/[s x Pa(exp -1/6)]. Data from many other FeCrAl(X) studies were similarly assessed to show general agreement with the relation for deltaD(sub gb,O,int.). This analysis reinforces the view that protective alumina scales grow by similar mechanisms for these Al-MAX phases and oxidation resistant FeCrAl alloys.

  18. Lightweight alumina refractory aggregate: Phase 3, Full-scale demonstration

    SciTech Connect

    Swansiger, T.G.; Pearson, A.

    1996-07-16

    Technical problems (higher than target fired density, and poor intermediate strength after burnout but before sintering) were addressed and solved; solution involved use of large loading of CP-5 alumina (controlled pore, rehydratable), increased loading of one of the binders, and a steam aging step. Resistance of the lightweight aggregate in a brick formulation to steel slag penetration was assessed in a preliminary test and found to be almost as good as that of T-64. Pelletized process economic feasibility study was updated, based on production levels of 10,000 and 20,000 mt/year, the most up- to-date raw material costs, and the assumption of a retrofit into the Arkansas plant tabular production facility. For the 10,000 mt/y production level, the required selling price of 35% more than the T- 64 selling price exceeds the {le}25% objective. The market survey will determine whether to proceed with the full scale demonstration that will produce at least 54.4 mt (120,000 lb) of the aggregate for incorporation into products, followed by end-user testing and evaluation.

  19. What are validated self-report adherence scales really measuring?: a systematic review

    PubMed Central

    Nguyen, Thi-My-Uyen; Caze, Adam La; Cottrell, Neil

    2014-01-01

    Aims Medication non-adherence is a significant health problem. There are numerous methods for measuring adherence, but no single method performs well on all criteria. The purpose of this systematic review is to (i) identify self-report medication adherence scales that have been correlated with comparison measures of medication-taking behaviour, (ii) assess how these scales measure adherence and (iii) explore how these adherence scales have been validated. Methods Cinahl and PubMed databases were used to search articles written in English on the development or validation of medication adherence scales dating to August 2012. The search terms used were medication adherence, medication non-adherence, medication compliance and names of each scale. Data such as barriers identified and validation comparison measures were extracted and compared. Results Sixty articles were included in the review, which consisted of 43 adherence scales. Adherence scales include items that either elicit information regarding the patient's medication-taking behaviour and/or attempts to identify barriers to good medication-taking behaviour or beliefs associated with adherence. The validation strategies employed depended on whether the focus of the scale was to measure medication-taking behaviour or identify barriers or beliefs. Conclusions Supporting patients to be adherent requires information on their medication-taking behaviour, barriers to adherence and beliefs about medicines. Adherence scales have the potential to explore these aspects of adherence, but currently there has been a greater focus on measuring medication-taking behaviour. Selecting the ‘right’ adherence scale(s) requires consideration of what needs to be measured and how (and in whom) the scale has been validated. PMID:23803249

  20. Finite element modeling of the effect of interface anomalies on thermal stresses in alumina scales

    SciTech Connect

    Wright, J.K.; Williamson, R.L.; Hou, P.Y.; Cannon, R.M.; Renusch, D.; Veal, B.; Grimsditch, M.

    1998-07-01

    The scales that grow from oxidation often develop a convoluted morphology or interface pores. High thermal stresses can develop locally and are potentially detrimental to the scale or interface integrity. Finite element simulations are used to examine residual thermal stresses and strains that result when these deviations from a flat interface have formed, and the resulting geometry is subsequently cooled to room temperature. A variety of geometries will be considered for alumina scales on a FeCrAl substrate.

  1. Finite element modeling of the effect of interface anomalies on thermal stresses in alumina scales.

    SciTech Connect

    Wright, J. K.

    1998-06-10

    The scales that grow from oxidation often develop a convoluted morphology or interface pores. High thermal stresses can develop locally and are potentially detrimental to the scale or interface integrity. Finite element simulations are used to examine residual thermal stresses and strains that result when these deviations from a flat interface have formed, and the resulting geometry is subsequently cooled to room temperature. A variety of geometries will be considered for alumina scales on a FeCrAl substrate.

  2. Effect of Impurities on O and Al Boundary Diffusion in Alumina: Application Alumina Scale Growth in Alloys

    DTIC Science & Technology

    2012-01-24

    uniform dispersion of Ni marker particles (0.5 vol%). The extent of the alumina spinel oxidation layer was measured as a function of the wedge...of Ni alone enhances transport by approximately a factor of 2 relative to undoped alumina. The diffusive transport of chromium in both pure and Y...doped fine-grained alumina has been investigated over the temperature range 1250 -1650 C. From a quantitative assessment of the chromium diffusion

  3. Development and Exploratory Scale-Up of Alumina-Forming Austenitic (AFA) Stainless Steels

    SciTech Connect

    Brady, Michael P; Magee, John H; Yamamoto, Yukinori; Maziasz, Philip J; Santella, Michael L; Pint, Bruce A; Bei, Hongbin

    2009-01-01

    This paper presents the results of the continued development of creep-resistant, alumina-forming austenitic (AFA) stainless steel alloys, which exhibit a unique combination of excellent oxidation resistance via protective alumina (Al2O3) scale formation and high-temperature creep strength through the formation of stable nano-scale MC carbides and intermetallic precipitates. Efforts in fiscal year 2009 focused on the characterization and understanding of long-term oxidation resistance and tensile properties as a function of alloy composition and microstructure. Computational thermodynamic calculations of the austenitic matrix phase composition and the volume fraction of MC, B2-NiAl, and Fe2(Mo,Nb) base Laves phase precipitates were used to interpret oxidation behavior. Of particular interest was the enrichment of Cr in the austenitic matrix phase by additions of Nb, which aided the establishment and maintenance of alumina. Higher levels of Nb additions also increased the volume fraction of B2-NiAl precipitates, which served as an Al reservoir during long-term oxidation. Ageing studies of AFA alloys were conducted at 750C for times up to 2000 h. Ageing resulted in near doubling of yield strength at room temperature after only 50 h at 750C, with little further increase in yield strength out to 2000 h of ageing. Elongation was reduced on ageing; however, levels of 15-25% were retained at room temperature after 2000 h of total ageing.

  4. Moisture-Induced Spallation and Interfacial Hydrogen Embrittlement of Alumina Scales

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2005-01-01

    Thermal expansion mismatch stresses and interfacial sulfur activity are the major factors producing primary Al2O3 scale spallation on high temperature alloys. However, moisture-induced delayed spallation appears as a secondary, but often dramatic, illustration of an additional mechanistic detail. A historical review of delayed failure of alumina scales and TBC s on superalloys is presented herein. Similarities with metallic phenomena suggest that hydrogen embrittlement from ambient humidity, resulting from the reaction Al+3H2O=Al(OH)3+3H(+)+3e(-), is the operative mechanism. This proposal was tested by standard cathodic hydrogen charging in 1N H2SO4, applied to Rene N5 pre-oxidized at 1150 C for 1000 1-hr cycles, and monitored by weight change, induced current, and microstructure. Here cathodic polarization at -2.0 V abruptly stripped mature Al2O3 scales at the oxide-metal interface. Anodic polarization at +2.0 V, however, produced alloy dissolution. Finally, with no applied voltage, the electrolyte alone produced neither scale spallation nor alloy dissolution. These experiments thus highlight the detrimental effects of hydrogen charging on alumina scale adhesion. It is proposed that interfacial hydrogen embrittlement is produced by moist air and is the root cause of both moisture-induced, delayed scale spallation and desktop TBC failures.

  5. Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

    PubMed Central

    Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2014-01-01

    Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices. PMID:25491282

  6. From Morisky to Hill-bone; self-reports scales for measuring adherence to medication.

    PubMed

    Culig, Josip; Leppée, Marcel

    2014-03-01

    There are a number of approaches to studying medication-taking behavior. Self-report measures have the benefits of being cheap, easy to administer, non-intrusive, and able to provide information on attitudes and beliefs about medication. Potential limitations to self-report are that the ability to understand the items, and willingness to disclose information, can affect response accuracy and, thus, questionnaire validity. A computerized systematic search of the PubMed databases identified articles on scales for medication adherence measuring using the MeSH terms medication adherence, compliance, and persistence combined with the terms questionnaire self-report. Adherence scales have identified mostly in the last few years (2005-2012). One of the main sources has been article (Lavsa et. al) which evaluated literature describing medication adherence surveys/scales to gauge patient behaviors at the point of care. Articles were included if they evaluated or reviewed self-reported adherence medication scale applicable to chronic diseases and with a good coefficient of internal consistency reliability (Cronbach's alpha (alpha)). Articles that contained data about self-report medication adherence scales use were included. A total of about one hundred articles were identified. Of those articles, 20% (20 of 100) were included in the review because of their relevance to the article topic. This article describes various self-report scales by which to monitor medication adherence, their advantages and disadvantages, and discusses the effectiveness of their application at different chronic diseases. There are many self-report scales for measuring medication adherence and their derivatives (or subscales). Due to the different nature of the diseases, there is no gold-standard scale for measuring medication adherence. It can be nevertheless concluded that the nearest to gold-standard is the Medication Adherence Questionnaire (MAQ) scale by Morisky et.al. but we found better

  7. Rapid fabrication of self-ordered porous alumina with 10-/sub-10-nm-scale nanostructures by selenic acid anodizing

    PubMed Central

    Nishinaga, Osamu; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

    2013-01-01

    Anodic porous alumina has been widely investigated and used as a nanostructure template in various nanoapplications. The porous structure consists of numerous hexagonal cells perpendicular to the aluminum substrate and each cell has several tens or hundreds of nanoscale pores at its center. Because the nanomorphology of anodic porous alumina is limited by the electrolyte during anodizing, the discovery of additional electrolytes would expand the applicability of porous alumina. In this study, we report a new self-ordered nanoporous alumina formed by selenic acid (H2SeO4) anodizing. By optimizing the anodizing conditions, anodic alumina possessing 10-nm-scale pores was rapidly assembled (within 1 h) during selenic acid anodizing without any special electrochemical equipment. Novel sub-10-nm-scale spacing can also be achieved by selenic acid anodizing and metal sputter deposition. Our new nanoporous alumina can be used as a nanotemplate for various nanostructures in 10-/sub-10-nm-scale manufacturing. PMID:24067318

  8. Influence of the Surface State on the Adherence of the Coating: Case of an Alumina Coating Plasma Sprayed on SiC Composites

    NASA Astrophysics Data System (ADS)

    Costil, S.; Lukat, S.; Verdy, C.; Coddet, C.

    2011-01-01

    In thermal spraying, adherence between the coating and the substrate appears as the fundamental point. To favor a good interaction between both, it is often necessary to clean and prepare the substrate surface. Conventionally, solvents and sand blasting are applied to remove the contaminants and increase the surface roughness for a mechanical anchorage. However, according to the substrate nature (ceramic) or the substrate morphology, it can be prejudicial to apply a mechanical treatment because of peeling of the surface or a decrease in the global properties. Then, to obtain an appropriate preparation, several techniques can be investigated, such as water jet, ice blasting, and heat treatment; as well, laser ablation can be an interesting technology to prepare the substrate surface. The aim of this work was to study the modifications induced by 10 ns single or cumulative pulses of a Q-switched Nd:YAG near-infrared laser and its influence on the interface adhesion. The case of an alumina coating sprayed on a ceramic matrix composite (CMC) was studied. In these conditions, the laser treatment seems favorable from the adherence viewpoint according to the mechanical effect (induced by a conelike structure) and the chemical effect.

  9. Moisture-Induced Delayed Alumina Scale Spallation on a Ni(Pt)Al Coating

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2009-01-01

    Delayed interfacial scale failure takes place after cooling for samples of a Ni(Pt)Al-coated CMSX4 single crystal superalloy, cycled at 1150 C for up to 2000 hr. One sample exhibited premature coating grain boundary wrinkling, alumina scale spallation to bare metal, and a final weight loss of 3.3 mg/cm2 . Spallation under ambient conditions was monitored with time after cooldown and was found to continue for 24 hr. This produced up to 0.05 mg/cm2 additional loss for each hold, accumulating 0.7 mg/cm 2 (20 percent of the total) over the course of the test. After test termination, water immersion produced an additional 0.15 mg/cm2 loss. (A duplicate sample produced much less wrinkling and time dependent spalling, maintaining a net weight gain.) The results are consistent with the general phenomena of moisture-induced delayed spallation (MIDS) of mature, distressed alumina scales formed on oxidation resistant M-Al alloys. Relative ambient humidity is discussed as the factor controlling adsorbed moisture, reaction with the substrate, and hydrogen effects on interface strength.

  10. Revisiting the internal consistency and factorial validity of the 8-item Morisky Medication Adherence Scale

    PubMed Central

    Zongo, Arsène; Guénette, Line; Moisan, Jocelyne; Guillaumie, Laurence; Lauzier, Sophie; Grégoire, Jean-Pierre

    2016-01-01

    Objective: To assess the internal consistency and factorial validity of the adapted French 8-item Morisky Medication Adherence Scale in assessing adherence to noninsulin antidiabetic drug treatment. Study Design and Setting: In a cross-sectional web survey of individuals with type 2 diabetes of the Canadian province of Quebec, self-reported adherence to the antidiabetes drug treatment was measured using the Morisky Medication Adherence Scale-8. We assessed the internal consistency of the Morisky Medication Adherence Scale-8 with Cronbach’s alpha, and factorial validity was assessed by identifying the underlying factors using exploratory factor analyses. Results: A total of 901 individuals completed the survey. Cronbach’s alpha was 0.60. Two factors were identified. One factor comprised five items: stopping medication when diabetes is under control, stopping when feeling worse, feeling hassled about sticking to the prescription, reasons other than forgetting and a cross-loading item (i.e. taking drugs the day before). The second factor comprised three other items that were all related to forgetfulness in addition to the cross-loading item. Conclusion: Cronbach’s alpha of the adapted French Morisky Medication Adherence Scale-8 was below the acceptable value of 0.70. This observed low internal consistency of the scale is probably related to the causal nature of the items of the scale but not necessarily a lack of reliability. The results suggest that the adapted French Morisky Medication Adherence Scale-8 is a two-factor scale assessing intentional (first factor) and unintentional (second factor) non-adherence to the noninsulin antidiabetes drug treatment. The scale could be used to separately identify these outcomes using scores obtained on each of the sub-scales. PMID:27895914

  11. Effect of edges and corners on stresses in thermally grown alumina scales

    SciTech Connect

    Renusch, D.; Muralidharan, G.; Uran, S.; Grimsditch, M.; Veal, B.W.; Wright, J.K.; Williamson, R.L.

    2000-02-01

    Residual stress near edges and corners of thermally grown alumina scales were investigated. In this study, an edge is the intersection of two orthogonal flat surfaces and a corner is the intersection of three such surfaces. Microfluorescence measurements, performed on alloys with composition Fe-28Al-5Cr (at.%, bal. Fe) oxidized at 900 C, showed a large (>50%) reduction in hydrostatic stress in the vicinity of edges and corners. Surprisingly, significant stress reduction persists out to distances twenty to fifty times the scale thickness from the edge. Finite-element analysis calculations confirm the experimental results and provide a considerably more detailed picture of the stress distribution and its components and show that much of the observed stress reduction near an edge, is due to plastic deformation of the underlying metal.

  12. Psychometric properties of three medication adherence scales in patients with rheumatoid arthritis.

    PubMed

    Salt, Elizabeth; Hall, Lynne; Peden, Ann R; Home, Rob

    2012-01-01

    Patient adherence to their health care protocols is important to encourage the best health outcomes in rheumatoid arthritis (RA); however, little attention has been given to assessing the psychometric properties of adherence measures in this patient population. The purpose of this study was to evaluate the psychometric properties of three existing self-report measures of medication adherence in a sample of patients with RA--the compliance-questionnaire-rheumatology (CQR), the Medication Adherence Report Scale (MARS), and the medication adherence scale (MAS). A cross-sectional study of 108 clinic patients with rheumatoid arthritis was conducted to evaluate the reliability and validity of the measures. Cronbach's alpha was .77 for both the CQR and a modified version of the MARS. For the MAS, the Kuder-Richardson 20 reliability was .25. Although not strong, test-retest reliability was adequate for all measures. Factor analysis indicated that both the MARS and the CQR measure two factors. All three instruments were moderately correlated with each other, with correlations ranging between .48 and .56. Although these scales were significantly correlated, moderate correlations among the scales indicate that they may not measure the same aspects of adherence. Among the three adherence measures, the modified MARS demonstrated the best evidence of reliability and validity and ease of administration in this sample of persons with RA.

  13. Moisture-Induced Delayed Spallation and Interfacial Hydrogen Embrittlement of Alumina Scales

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2008-01-01

    While interfacial sulfur is the primary chemical factor affecting Al2O3 scale adhesion, moisture-induced delayed spallation appears as a secondary, but impressive, mechanistic detail. Similarities with bulk metallic phenomena suggest that hydrogen embrittlement from ambient humidity, resulting from the reaction Al(sub alloy)+3(H2O)(sub air) = Al(OH)(-) (sub 3) +3H(+) may be the operative mechanism. This proposal was tested on pre-oxidized Rene N5 by standard cathodic hydrogen charging in 1N H2SO4, as monitored by weight change, induced current, and microstructure. Cathodic polarization at -2.0 V abruptly stripped mature Al2O3 scales at the oxide-metal interface. Anodic polarization at +2.0 V, however, produced alloy dissolution. Finally, with no applied voltage, the acid electrolyte produced neither scale spallation nor alloy dissolution. Thus, hydrogen charging was detrimental to alumina scale adhesion. Moisture-induced interfacial hydrogen embrittlement is concluded to be the cause of delayed scale spallation and desktop thermal barrier coating failures.

  14. Oxygen Permeability and Grain-Boundary Diffusion Applied to Alumina Scales

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Jacobson, Nathan S.; Gleeson, Brian; Hovis, David B.; Heuer, Arthur H.

    2013-01-01

    High-temperature oxygen permeability measurements had determined grain-boundary diffusivities (deltaD(sub gb)) in bulk polycrystalline alumina (Wada, Matsudaira, and Kitaoka). They predict that oxygen deltaD(sub gb,O) varies with oxygen pressure as P(O2)(sup -1/6) at low pressure whereas aluminum deltaD(sub gb),Al varies with P(O2)(sup +3/16) at high pressure. These relations were used to evaluate alumina scale growth in terms of diffusivity and grain size. A modified Wagner treatment for dominant inward oxygen growth produces the concise solution: ?(sub i) = k(sub p,i)×G(sub i) = 12 deltaD(sub gb,O,int), where ?(sub i) is a constant and k(sub p,i) and G(sub i) refer to instantaneous values of the scale parabolic growth constant and grain size, respectively. A commercial FeCrAl(Zr) alloy was oxidized at 1100 to 1400 degC to determine k(sub p,i), interfacial grain size, ?, and thus deltaD(sub gb,O,int). The deltaD(sub gb,O,int) values predicted from oxidation at (375 kJ/mole) were about 20 times less than those obtained above (at 298 kJ/mole), but closer than extrapolations from high-temperature bulk measurements. The experimental oxidation results agree with similar FeCrAl(X) studies, especially where both k(sub p,i) and G(sub i) were characterized. This complete approach accounts for temperature-sensitive oxidation effects of grain enlargement, equilibrium interface pressure variation, and grain-boundary diffusivity.

  15. Development of a Patient Adherence Scale for Exposure and Response Prevention Therapy

    PubMed Central

    Simpson, Helen Blair; Maher, Michael; Page, Jessica R.; Gibbons, Carly J.; Franklin, Martin E.; Foa, Edna B.

    2014-01-01

    Exposure and response prevention (EX/RP) is an evidence-based treatment for obsessive-compulsive disorder (OCD). For EX/RP to be maximally effective, it is believed that patients must adhere outside of sessions to the procedures they learn in therapy. To date, there is no standard measure of patient EX/RP adherence, despite the importance of accurately assessing EX/RP adherence in both clinical research and practice. This paper describes the development of the Patient EX/RP Adherence Scale (PEAS), which assesses the patient's between-session adherence to the therapist's EX/RP instructions, and presents initial data on the scale's reliability and validity. The scale was designed to focus on the key procedures of EX/RP and to be brief enough to be used at each treatment session. The scale demonstrates excellent interrater reliability and good face and content validity. The usefulness of the scale is considered in the context of being an important tool to researchers trying to understand and improve outcomes of EX/RP for OCD as well as to EX/RP therapists in clinical practice. Future research will need to test the scale's reliability and validity in a larger sample of patients over the course of treatment. PMID:20171325

  16. Wear degradation of long-term in vivo exposed alumina-on-alumina hip joints: linking nanometer-scale phenomena to macroscopic joint design.

    PubMed

    Takahashi, Yasuhito; Sugano, Nobuhiko; Zhu, Wenliang; Nishii, Takashi; Sakai, Takashi; Takao, Masaki; Pezzotti, Giuseppe

    2012-02-01

    The wear behavior of alumina femoral heads was examined at follow-up periods between 7.7 and 10.7 years. Four head retrievals of the same size (28 mm in diameter) were divided into two groups with different design characteristics. Systematically using scanning electron and atomic force microscopy procedures, wear characteristics could be classified on the entire heads according to five zones with increasing degrees of wear damage (Grade 1-5), in addition to one zone of stripe wear (Grade SW). The stripe wear zone showed quite different topographical features as compared to frictionally worn zones. Furthermore, hip implants designed with different clearances are shown to lead to different wear patterns on the femoral head surface, the smaller the clearance the wider the worn surface area. Cathodoluminescence piezo-spectroscopy provided information about the residual stress state in surfaces worn to different degrees and helped clarifying the wear mechanisms on the microscopic scale.

  17. Validation of the Adherence Determinants Questionnaire scale among women with breast and cervical cancer1

    PubMed Central

    Lessa, Paula Renata Amorim; Ribeiro, Samila Gomes; Aquino, Priscila de Souza; de Almeida, Paulo Cesar; Pinheiro, Ana Karina Bezerra

    2015-01-01

    Objectives: the aim was to translate and culturally adapt the Adherence Determinants Questionnaire scale for the Portuguese language in the Brazilian context, and to check its reliability and validity to analyze the elements of the adherence of patients to the clinical treatment for breast and cervical cancer. Method: this was a methodological study, carried out in two oncology reference centers. The sample consisted of 198 participants, with 152 being treated for breast cancer and 46 being treated for cervical cancer. The content validation was performed by a committee of experts. The construct validation was demonstrated through factor analysis and the reliability was analyzed using Cronbach's alpha. Results: the committee of experts made the necessary adjustments so that the scale was adapted to the Brazilian context. The factor analysis suggested a reduction from seven to five factors and the maintenance of 38 items similar to those of the original scale. The reliability, investigated through Cronbach's alpha, was .829, showing high internal consistency. Conclusion: it was concluded that the Brazilian version of the Adherence Determinants Questionnaire scale is a valid and reliable instrument that is able to measure the elements of adherence to the treatment for breast and cervical cancer. PMID:26487149

  18. Highly efficient and large-scale fabrication of superhydrophobic alumina surface with strong stability based on self-congregated alumina nanowires.

    PubMed

    Peng, Shan; Tian, Dong; Yang, Xiaojun; Deng, Wenli

    2014-04-09

    In this study, a large-area superhydrophobic alumina surface with a series of superior properties was fabricated via an economical, simple, and highly effective one-step anodization process, and subsequently modified with low-surface-energy film. The effects of the anodization parameters including electrochemical anodization time, current density, and electrolyte temperature on surface morphology and surface wettability were investigated in detail. The hierarchical alumina pyramids-on-pores (HAPOP) rough structure which was produced quickly through the one-step anodization process together with a low-surface-energy film deposition [1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDES) and stearic acid (STA)] confer excellent superhydrophobicity and an extremely low sliding angle. Both the PDES-modified superhydrophobic (PDES-MS) and the STA-modified superhydrophobic (STA-MS) surfaces present fascinating nonwetting and extremely slippery behaviors. The chemical stability and mechanical durability of the PDES-MS and STA-MS surfaces were evaluated and discussed. Compared with the STA-MS surface, the as-prepared PDES-MS surface possesses an amazing chemical stability which not only can repel cool liquids (water, HCl/NaOH solutions, around 25 °C), but also can show excellent resistance to a series of hot liquids (water, HCl/NaOH solutions, 30-100 °C) and hot beverages (coffee, milk, tea, 80 °C). Moreover, the PDES-MS surface also presents excellent stability toward immersion in various organic solvents, high temperature, and long time period. In particular, the PDES-MS surface achieves good mechanical durability which can withstand ultrasonication treatment, finger-touch, multiple fold, peeling by adhesive tape, and even abrasion test treatments without losing superhydrophobicity. The corrosion resistance and durability of the diverse-modified superhydrophobic surfaces were also examined. These fascinating performances makes the present method suitable for large-scale

  19. The Scale of Self-Efficacy Expectations of Adherence to Antiretroviral Treatment: A Tool for Identifying Risk for Non-Adherence to Treatment for HIV

    PubMed Central

    Drachler, Maria de Lourdes; Drachler, Carlos Wietzke; Teixeira, Luciana Barcellos; de Carvalho Leite, José Carlos

    2016-01-01

    Background Identification of risk for non-adherence to treatment is a challenge for personalized care for people living with HIV. Standardized questionnaires of patients’ expectations of their capability to overcome obstacles for treatment adherence may be used as a pre-screening for risk identification. A scale of self-efficacy expectations of adherence to antiretroviral treatment (SEA-ART scale) was previously developed. This study assesses the scale validity in predicting non-adherence to ART in adults living with HIV. Methods and Findings A prospective cohort study applied a 21-item SEA-ART scale to 275 adults in ART treatment at an outpatient public service for HIV in Southern Brazil. ART medications taken were assessed at one-month follow-up; ART adherence was devised as an intake of 95% and more of the prescribed medication. A SEA-ART score was calculated by adding up the scores of all items. Multivariable logistic regression and the Area Under the Receiver-Operating-Characteristic Curve (AUROC) were applied to examine the ability of the SEA-ART score to predict non-adherence at follow-up. The SEA-ART score varied from 21 to 105; mean 93.9; median 103.0. Non-adherence was 30.3% (n = 81/267). The odds of non-adherence was 8% lower for each unit increase of the SEA-ART score; after adjustment for age, sex, formal education and time in treatment (OR = 0.92; 95%CI 0.90–0.95; LRT for linear trend, p = 0.002). The AUROC was 0.80 (95%CI 0.73–0.87; p<0.001). The SEA-ART optimal cut-off value was 101, providing a sensitivity of 76.5%, a specificity of 73.1%, a positive predictive value of 55.4% and a negative predictive value of 87.7%. There was no evidence of difference in sensitivity, and specificity among groups organized by age, gender, formal education and time in treatment. Conclusions The SEA-ART scale appears to have a good capacity to discriminate between adherents and non-adherents at one-month follow-up. Further studies should confirm these results

  20. Adherent Al2O3 scales produced on undoped NiCrAl alloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    1986-01-01

    Repeated oxidation and polishing of high purity Ni-15Cr-13Al has dramatically changed its cyclic oxidation behavior from nonadherent to adherent. No apparent change in scale phase, morphology or interface structure occurred during this transition, dismissing any mechanism based on pegging, vacancy sink, or growth stress. The principle change that did occur was a reduction in the sulfur content from 10 ppmw to 3 ppmw after 25 cycles at 1120 C. These observations are used to support the model of Al2O3 scale adherence put forth by Smeggil et al. which claims that Al2O3 scale spallation occurs due to sulfur segregation and bond deterioration at the oxide-metal interface.

  1. Utility of the Morisky Medication Adherence Scale in gout: a prospective study

    PubMed Central

    Tan, CSL; Teng, GG; Chong, KJ; Cheung, PP; Lim, AYN; Wee, HL; Santosa, A

    2016-01-01

    Background The outcomes of any chronic illness often depend on patients’ adherence with their treatment. A tool is lacking to assess adherence in gout that is standardized, allows real-time feedback, and is easy to understand. Objective We set out to evaluate the utility of the 8-item Morisky Medication Adherence Scale (MMAS-8) in monitoring medication adherence in a multiethnic Asian gout cohort on urate-lowering therapy (ULT). Methods This cohort study recruited patients with gout where baseline and 6-monthly clinical data, self-report of adherence, and health status by Gout Impact Scale (GIS) and EuroQoL-5 dimension 3 levels were collected. Those who received at least 9 months of ULT were analyzed. Convergent and construct validities of MMAS-8 were evaluated against medication possession ratio (MPR) and known groups, clinical outcomes, and patient-reported outcomes. Internal consistency and test–retest reliability were assessed using Cronbach’s alpha and intraclass correlation coefficient (ICC), respectively. Results Of 91 patients, 92.3% were male, 72.5% Chinese with mean age 53.5 years. MMAS-8 (mean 6.17) and MPR (mean 96.3%) were poorly correlated (r=0.069, P=0.521). MMAS-8 did not differ between those who did or did not achieve target serum urate (SU) <360 µmol/L (P=0.852); or among those whose SU improved, stagnated, or worsened during follow-up (P=0.777). Adherence was associated with age (β=0.256, P=0.015) and education level (P=0.011) but not comorbidities, polypharmacy, or flare frequency. Concerns for medication side effects and anxiety or depression were associated with lower MMAS-8 (P<0.005). Internal consistency was acceptable (α=0.725) and test–retest reliability was satisfactory (ICC =0.70, 95% confidence interval [CI] 0.36–0.88). Conclusion MMAS-8 had limited construct validity in assessing medication adherence to ULT in our gout patients. Nevertheless, it identified patients bothered or worried about ULT side effects, and those with

  2. Verifying quantitative stigma and medication adherence scales using qualitative methods among Thai youth living with HIV/AIDS.

    PubMed

    Fongkaew, Warunee; Viseskul, Nongkran; Suksatit, Benjamas; Settheekul, Saowaluck; Chontawan, Ratanawadee; Grimes, Richard M; Grimes, Deanna E

    2014-01-01

    HIV/AIDS-related stigma has been linked to poor adherence resulting in drug resistance and the failure to control HIV. This study used both quantitative and qualitative methods to examine stigma and its relationship to adherence in 30 HIV-infected Thai youth aged 14 to 21 years. Stigma was measured using the HIV stigma scale and its 4 subscales, and adherence was measured using a visual analog scale. Stigma and adherence were also examined by in-depth interviews. The interviews were to determine whether verbal responses would match the scale's results. The mean score of stigma perception from the overall scale and its 4 subscales ranged from 2.14 to 2.45 on a scale of 1 to 4, indicating moderate levels of stigma. The mean adherence score was .74. The stigma scale and its subscales did not correlate with the adherence. Totally, 17 of the respondents were interviewed. Contrary to the quantitative results, the interviewees reported that the stigma led to poor adherence because the fear of disclosure often caused them to miss medication doses. The differences between the quantitative and the qualitative results highlight the importance of validating psychometric scales when they are translated and used in other cultures.

  3. Validation of the VERITAS-Pro treatment adherence scale in a Spanish sample population with hemophilia

    PubMed Central

    Cuesta-Barriuso, Rubén; Torres-Ortuño, Ana; Galindo-Piñana, Pilar; Nieto-Munuera, Joaquín; Duncan, Natalie; López-Pina, José Antonio

    2017-01-01

    Purpose We aimed to conduct a validation in Spanish of the Validated Hemophilia Regimen Treatment Adherence Scale – Prophylaxis (VERITAS-Pro) questionnaire for use in patients with hemophilia under prophylactic treatment. Patients and methods The VERITAS-Pro scale was adapted through a process of back translation from English to Spanish. A bilingual native Spanish translator translated the scale from English to Spanish. Subsequently, a bilingual native English translator translated the scale from Spanish to English. The disagreements were resolved by agreement between the research team and translators. Seventy-three patients with hemophilia, aged 13–62 years, were enrolled in the study. The scale was applied twice (2 months apart) to evaluate the test–retest reliability. Results Internal consistency reliability was lower on the Spanish VERITAS-Pro than on the English version. Test–retest reliability was high, ranging from 0.83 to 0.92. No significant differences (P>0.05) were found between test and retest scores in subscales of VERITAS-Pro. In general, Spanish patients showed higher rates of nonadherence than American patients in all subscales. Conclusion The Spanish version of the VERITAS-Pro has high levels of consistency and empirical validity. This scale can be administered to assess the degree of adherence of prophylactic treatment in patients with hemophilia.

  4. Validated adherence scales used in a measurement-guided medication management approach to target and tailor a medication adherence intervention: a randomised controlled trial

    PubMed Central

    Nguyen, Thi-My-Uyen; La Caze, Adam; Cottrell, Neil

    2016-01-01

    Objective To determine if a targeted and tailored intervention based on a discussion informed by validated adherence scales will improve medication adherence. Design Prospective randomised trial. Setting 2 community pharmacies in Brisbane, Australia. Methods Patients recently initiated on a cardiovascular or oral hypoglycaemic medication within the past 4–12 weeks were recruited from two community pharmacies. Participants identified as non-adherent using the Medication Adherence Questionnaire (MAQ) were randomised into the intervention or control group. The intervention group received a tailored intervention based on a discussion informed by responses to the MAQ, Beliefs about Medicines Questionnaire-Specific and Brief Illness Perception Questionnaire. Adherence was measured using the MAQ at 3 and 6 months following the intervention. Results A total of 408 patients were assessed for eligibility, from which 152 participants were enrolled into the study. 120 participants were identified as non-adherent using the MAQ and randomised to the ‘intervention’ or ‘control’ group. The mean MAQ score at baseline in the intervention and control were similar (1.58: 95% CI (1.38 to 1.78) and 1.60: 95% CI (1.43 to 1.77), respectively). There was a statistically significant improvement in adherence in the intervention group compared to control at 3 months (mean MAQ score 0.42: 95% CI (0.27 to 0.57) vs 1.58: 95% CI (1.42 to 1.75); p<0.001). The significant improvement in MAQ score in the intervention group compared to control was sustained at 6 months (0.48: 95% CI (0.31 to 0.65) vs 1.48: 95% CI (1.27 to 1.69); p<0.001). Conclusions An intervention that targeted non-adherent participants and tailored to participant-specific reasons for non-adherence was successful at improving medication adherence. Trial registration number ACTRN12613000162718; Results. PMID:27903564

  5. The Nursing Assessment of Medication Acceptance: the reliability and validity of a schizophrenia medication adherence scale

    PubMed Central

    Hori, Hikaru; Ueda, Nobuhisa; Shiozuka, Hideki; Igata, Ryohei; Miki, Tazuko; Atake, Kiyokazu; Takeuchi, Yuji; Shirozu, Hiroaki; Ohara, Naotoshi; Konishi, Yuki; Nagai, Hiroshi; Sakurai, Noriaki; Kubota, Takanori; Yoshimura, Reiji

    2016-01-01

    Background: Many patients with schizophrenia have low medication adherence. There is, however, no objective assessment scale that can be used by nurses or caregiver specialists. The Nursing Assessment of Medication Acceptance (NAMA) was developed to assess patients’ medication adherence. The aim of this study was to examine the validity and reliability of the NAMA in patients with schizophrenia. Methods: A total of 121 Japanese patients with schizophrenia were enrolled. All patients underwent evaluation using the NAMA and the Drug Attitude Inventory (DAI-10). Reliability was investigated using a test-retest method and a parallel-test method. To determine the test-retest reliability of the NAMA, we tested 101 schizophrenia patients twice, with the second assessment 2–4 weeks after the date of the first assessment. For validity verification, standard-related validity and the degree of concordance with the DAI-10 scores were measured. Results: The Cronbach’s alpha value of the NAMA in schizophrenia was 0.88. The test-retest correlation coefficients were all between 0.53–0.74. The total scores and all subscores for the NAMA were significantly correlated, and the NAMA total scores were significantly correlated with the DAI-10 total scores. Conclusions: The NAMA shows good reliability and validity in measuring medication adherence in schizophrenia. PMID:28101319

  6. Visual analogue scale (VAS) measurement of antiretroviral adherence in people living with HIV (PLWH): a meta-analysis.

    PubMed

    Finitsis, David J; Pellowski, Jennifer A; Huedo-Medina, Tania B; Fox, Matthew C; Kalichman, Seth C

    2016-12-01

    Effective treatment of HIV hinges upon maintaining adequate antiretroviral therapy adherence. Accurate, cost-effective measurement of medication adherence is needed to best respond to the HIV pandemic. The visual analogue scale (VAS) appears to be a simple and easy to use measure of adherence but the current literature on its use is mixed. This meta-analysis (1) describes VAS concordance with other measures of medication adherence and viral load; and (2) examines how research methods moderate the reported strength of the VAS-viral load relationship. Literature searches were conducted electronically and by hand with a total of 20 studies included in the present study. The VAS showed large strength associations with most other measures of adherence and a smaller association with viral load. More rigorous methodological quality significantly improved the VAS-viral load effect size. We conclude with optimization recommendations for VAS use in clinical practice and research design.

  7. Feasibility and process scale-up low cost alumina fibers for advanced Re-usable Surface Insulation (RSI)

    NASA Technical Reports Server (NTRS)

    Pearson, A.

    1975-01-01

    The objective of this program was to establish feasibility of a process to produce low cost aluminum oxide fibers having sufficient strength, flexibility, and thermal stability for multiple re-use at temperatures to 1480 C in advanced RSI type heat shields for reentry vehicles. Using bench-scale processing apparatus, the Alcoa 'Saphiber' process was successfully modified to produce nominally 8 microns diameter polycrystalline alpha-alumina fiber. Thermal stability was demonstrated in vacuum reheating tests to 1371 C and in atmospheric reheating to 1483 C. Individual fiber properties of strength, modulus, and flexibility were not determined because of friability and short length of the fiber. Rigidized tile produced from fiber of nominally 8, 20 and 40 micron diameter had thermal conductivities significantly higher than those of RSI SiO2 or mullite at relatively low temperature but became comparable above about 1000 C. Tile densities were high due to short fiber length, especially in the coarser diameter fiber. No significant effect of fiber diameter on thermal properties could be determined form the data. Mechanical properties of tiles deteriorated as fiber diameter increased.

  8. Psychometric properties of the Polish version of the eight-item Morisky Medication Adherence Scale in hypertensive adults.

    PubMed

    Jankowska-Polanska, Beata; Uchmanowicz, Izabella; Chudiak, Anna; Dudek, Krzysztof; Morisky, Donald E; Szymanska-Chabowska, Anna

    2016-01-01

    Low adherence to pharmacological treatment is often associated with poor blood pressure control, but identification of nonadherent patients in outpatient settings is difficult. The aim of the study was to translate and evaluate the psychometric properties of the Polish version of the structured self-report eight-item Morisky Medication Adherence Scale (MMAS-8) among patients with hypertension. The study was conducted in a family doctor practice between January and July 2015. After a standard "forward-backward" procedure to translate MMAS-8 into Polish, the questionnaire was administered to 160 patients with hypertension. Reliability was tested using a measure of internal consistency (Cronbach's α) and test-retest reliability. Validity was confirmed using known group validity. Three levels of adherence were considered based on the following scores: 0 to <6 (low); 6 to <8 (medium); and 8 (high). Complete questionnaires were returned by 110 respondents (mean age: 60.7 years ±12.6; 54.6% were female). The mean number of pills taken daily was 3.61±4.31. The mean adherence score was 6.42± 2.0. Moderate internal consistency was found (Cronbach's α=0.81), and test-retest reliability was satisfactory (r=0.461-0.905; P<0.001). Reproducibility expressed by Cohen's κ coefficient =0.61 was good. In high-adherent patients, the percentage of well-controlled blood pressure was higher than in low-adherent patients (33.3% vs 19.1%, χ (2)=0.87, P=0.648). Psychometric evaluation of the Polish version of the MMAS-8 indicates that it is a reliable and valid measure tool to detect nonadherent patients. The MMAS-8 may be routinely used to support communication about the medication-taking behavior in hypertensive patients.

  9. Psychometric properties of the Polish version of the eight-item Morisky Medication Adherence Scale in hypertensive adults

    PubMed Central

    Jankowska-Polanska, Beata; Uchmanowicz, Izabella; Chudiak, Anna; Dudek, Krzysztof; Morisky, Donald E; Szymanska-Chabowska, Anna

    2016-01-01

    Low adherence to pharmacological treatment is often associated with poor blood pressure control, but identification of nonadherent patients in outpatient settings is difficult. The aim of the study was to translate and evaluate the psychometric properties of the Polish version of the structured self-report eight-item Morisky Medication Adherence Scale (MMAS-8) among patients with hypertension. The study was conducted in a family doctor practice between January and July 2015. After a standard “forward–backward” procedure to translate MMAS-8 into Polish, the questionnaire was administered to 160 patients with hypertension. Reliability was tested using a measure of internal consistency (Cronbach’s α) and test–retest reliability. Validity was confirmed using known group validity. Three levels of adherence were considered based on the following scores: 0 to <6 (low); 6 to <8 (medium); and 8 (high). Complete questionnaires were returned by 110 respondents (mean age: 60.7 years ±12.6; 54.6% were female). The mean number of pills taken daily was 3.61±4.31. The mean adherence score was 6.42± 2.0. Moderate internal consistency was found (Cronbach’s α=0.81), and test–retest reliability was satisfactory (r=0.461–0.905; P<0.001). Reproducibility expressed by Cohen’s κ coefficient =0.61 was good. In high-adherent patients, the percentage of well-controlled blood pressure was higher than in low-adherent patients (33.3% vs 19.1%, χ2=0.87, P=0.648). Psychometric evaluation of the Polish version of the MMAS-8 indicates that it is a reliable and valid measure tool to detect nonadherent patients. The MMAS-8 may be routinely used to support communication about the medication-taking behavior in hypertensive patients. PMID:27672314

  10. Validation of the Persian Version of the 8-Item Morisky Medication Adherence Scale (MMAS-8) in Iranian Hypertensive Patients

    PubMed Central

    Moharamzad, Yashar; Saadat, Habibollah; Shahraki, Babak Nakhjavan; Rai, Alireza; Saadat, Zahra; Aerab-Sheibani, Hossein; Naghizadeh, Mohammad Mehdi; Morisky, Donald E.

    2015-01-01

    The reliability and validity of the 8-item Morisky Medication Adherence Scale (MMAS-8) was assessed in a sample of Iranian hypertensive patients. In this multi-center study which lasted from August to October 2014, a total of 200 patients who were suffering from hypertension (HTN) and were taking anti-hypertensive medication(s) were included. The cases were accessed through private and university health centers in the cities of Tehran, Karaj, Kermanshah, and Bafgh in Iran and were interviewed face-to-face by the research team. The validated Persian translation of the MMAS-8 was provided by the owner of this scale. This scale contains 7 questions with “Yes” or “No” response choices and an additional Likert-type question (totally 8 questions). The total score ranges from 0 to 8 with higher scores reflecting better medication adherence. Mean (±SD) overall MMAS-8 score was 5.57 (±1.86). There were 108 (54%), 62 (31%), and 30 (15%) patients in the low, moderate, and high adherence groups. Internal consistency was acceptable with an overall Cronbach’s α coefficient of 0.697 and test–retest reliability showed good reproducibility (r= 0.940); P< 0.001. Overall score of the MMAS-8 was significantly correlated with systolic BP (r= - 0.306) and diastolic BP (r= - 0.279) with P< 0.001 for both BP measurements. The Chi-square test showed a significant relationship between adherence level and BP control (P= 0.016). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the scale were 92.8%, 22.3%, 52.9%, and 76.7%, respectively. The Persian version of the MMAS had acceptable reliability and validity in Iranian hypertensive patients. This scale can be used as a standard and reliable tool in future studies to determine medication adherence of Persian-speaking patients with chronic conditions. PMID:25946926

  11. Effects of water vapor on the high temperature oxidation of alumina-forming coatings and nickel base superalloys

    NASA Astrophysics Data System (ADS)

    Maris-Sida, Monica C.

    Oxidation studies were performed at 1100°C, 900°C and 700°C in dry, air and air containing fixed partial pressures of water vapor on specimens of Ni base superalloys and coatings on these alloys that form alpha-alumina scales under oxidizing conditions. The materials studied included Rene N5, PWA1484, CMSX4, diffusion aluminide coatings (with or without Pt addition) on Rene N5, Thermal Barrier Coatings on Rene N5, and a Ni-8wt%Cr-6wt%Al model. All of these alloys and metallic coatings are normally alpha-alumina-formers under oxidization conditions. The observed important effects of water vapor include: (1) Increased severity of cracking and spalling of alpha-alumina scales in wet environments especially for those systems with alumina only moderately adherent in dry air; (2) Water vapor affects the nucleation and growth of alpha-alumina scales---the growth rate of alpha-alumina is increased in water vapor conditions; (3) Thicker oxides form during oxidation in wet air than dry air. The transient oxidation phenomenon is affected by the presence of water vapor due to more rapid growth of NiO during the transient period. The selective oxidation of aluminum is inhibited in water vapor conditions, even more adverse effects of water vapor are observed as the oxidation temperature is lowered; (4) Spinel phase forms on top of the alumina scales during long term oxidation. Current results indicate that nickel diffusion at alumina grain boundaries significantly contributes to the formation of new spinel phase at the oxide/gas interface and water vapor is found to enhance this process. Mechanisms for these observations are proposed.

  12. Adaptation and evaluation of the measurement properties of the Brazilian version of the Self-efficacy for Appropriate Medication Adherence Scale1

    PubMed Central

    Pedrosa, Rafaela Batista dos Santos; Rodrigues, Roberta Cunha Matheus

    2016-01-01

    Objectives: to undertake the cultural adaptation of, and to evaluate the measurement properties of, the Brazilian version of the Self-efficacy for Appropriate Medication Adherence Scale in coronary heart disease (CHD) patients, with outpatient monitoring at a teaching hospital. Method: the process of cultural adaptation was undertaken in accordance with the international literature. The data were obtained from 147 CHD patients, through the application of the sociodemographic/clinical characterization instrument, and of the Brazilian versions of the Morisky Self-Reported Measure of Medication Adherence Scale, the General Perceived Self-Efficacy Scale, and the Self-efficacy for Appropriate Medication Adherence Scale. Results: the Brazilian version of the Self-efficacy for Appropriate Medication Adherence Scale presented evidence of semantic-idiomatic, conceptual and cultural equivalencies, with high acceptability and practicality. The floor effect was evidenced for the total score and for the domains of the scale studied. The findings evidenced the measure's reliability. The domains of the Brazilian version of the Self-efficacy for Appropriate Medication Adherence Scale presented significant inverse correlations of moderate to strong magnitude between the scores of the Morisky scale, indicating convergent validity, although correlations with the measure of general self-efficacy were not evidenced. The validity of known groups was supported, as the scale discriminated between "adherents" and "non-adherents" to the medications, as well as to "sufficient dose" and "insufficient dose". Conclusion: the Brazilian version of the Self-efficacy for Appropriate Medication Adherence Scale presented evidence of reliability and validity in coronary heart disease outpatients. PMID:27192417

  13. Validation of the Medication Adherence Rating Scale in homeless patients with schizophrenia: Results from the French Housing First experience

    PubMed Central

    Zemmour, K.; Tinland, A.; Boucekine, M.; Girard, V.; Loubière, S.; Resseguier, N.; Fond, G.; Auquier, P.; Boyer, L.; Apostolidis, T.; Birmes, P.; Bossetti, T.; Bouloudnine, R.; Combes, B.; Debieve, J.; Falissard, B.; Greacen, T.; Laval, C.; Lancon, C.; Le Cardinal, P.; Mantovani, J.; Moreau, D.; Naudin, J.; Rhunter, P.; Videau, B.

    2016-01-01

    The Medication Adherence Rating Scale (MARS) is one of the most widely used measurements of adherence in schizophrenia (SZ), but there is no available data regarding its psychometric properties in homeless SZ patients (HSZ). The aim of this study was therefore to assess the psychometric properties of the MARS in a large multicenter sample of HSZ subjects. This multi-centre prospective study was conducted in the following 4 French cities: Lille, Marseille, Paris and Toulouse. Three hundred and fifty-three patients were included. The 3-factor structure of the MARS was confirmed using confirmatory factor analysis: RMSEA = 0.045, CFI = 0.98, TLI = 0.97 and WRMR = 0.76. The unidimensionality of each factor was supported by the satisfactory INFIT statistics. Item internal consistencies were all higher than 0.20 and the Kuder–Richardson were higher than to 0.6, except for factor 2, which was closed to 0.5. Significant associations with symptoms, functioning and quality of life showed satisfactory external validity. The acceptability was satisfactory with missing data lower than 5% for each dimension. The MARS is a short self-administered instrument with acceptable psychometric properties in homeless SZ patients that yields interesting information about medication adherence. PMID:27534796

  14. Developing a Small-scale De-fluoridation Filter for use in Rural Northern Ghana with Activated Alumina as the Sorbent

    NASA Astrophysics Data System (ADS)

    Craig, L.; Stillings, L. L.; Decker, D.; Thomas, J.

    2013-12-01

    reaction time). The F- loading onto activated alumina did not change with grain size. However time to equilibrium increased dramatically with a decrease in grain size - after one hour of reaction time, the larger grain size adsorbed only 59% of F-, while at the finer grain size 90% was adsorbed. Future work will determine the volume of high F- water that can be treated before activated alumina needs to be regenerated or changed. These data will be incorporated into the design of a small-scale F-1 adsorption filter in the study area, and will predict the longevity of activated alumina as the sorbent.

  15. Microstructure and Residual Stress of Alumina Scale Formed on Ti2AlC at High Temperature in Air

    SciTech Connect

    Byeon, J; Liu, j; Hopkins, m; Fischer, W; Park, K; Brady, Michael P; Radovic, Miladin; Sohn, Yong Ho

    2007-01-01

    Ti2AlC ternary carbide is being explored for various high temperature applications owing to its high strength at high temperatures, excellent thermal-shock resistance, and high electrical conductivity. In this study, isothermal oxidation at 1000 XC, 1200 XC, and 1400 XC for up to 25 hours, as well as 1,000 1-hour cyclic oxidation at 1200 XC were performed in air to examine the oxidation behavior of Ti2AlC. Characteristics of the oxide scale developed in air, including mass change, residual stress in the -Al2O3 scale, phase constituents and microstructure, were examined as functions of time and temperature by thermogravimetry, photostimulated luminescence, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy via focused ion beam in-situ lift-out. A continuous and adherent -Al2O3 scale underneath a discontinuous-transient rutile-TiO2 scale was identified in the oxide scale developed at 1000 XC and 1200 XC. At 1400 XC, Al2TiO5 was identified as the discontinuous-transient scale above the continuous and adherent -Al2O3 scale. The -Al2O3 scale thickened to more than 15 m after 25 hours of isothermal oxidation at 1400 XC, and after 1,000 1-hour cyclic oxidation at 1200 XC, yet remained adherent and protective. The compressive residual stress determined by photoluminescence for the -Al2O3 scale remained under 0.65 GPa for the specimens oxidized up to 1400 XC for 25 hours. The small magnitude of the compressive residual stress may impart the high spallation-resistance of the protective -Al2O3 scale developed on Ti2AlC.

  16. Developing a Small-Scale De-Fluoridation Filter for Use in Rural Northern Ghana with Activated Alumina As the Sorbent

    NASA Astrophysics Data System (ADS)

    Craig, L.; Stillings, L. L.

    2014-12-01

    reaction time, the larger grain size adsorbed only 59% of F-, while at the finer grain size 90% was adsorbed. Future work will determine the volume of high F- water that can be treated before activated alumina needs to be regenerated or changed. These data will aid in the design of a small-scale F- adsorption filter in the study area, and will predict the longevity of activated alumina as the sorbent.

  17. Effects of thermal cycling parameters on residual stresses in alumina scales of CoNiCrAlY and NiCoCrAlY bond coats

    DOE PAGES

    Nordhorn, Christian; Mücke, Robert; Unocic, Kinga A.; ...

    2014-08-20

    In this paper, furnace cycling experiments were performed on free-standing high-velocity oxygen-fuel bond coat samples to investigate the effect of material composition, surface texture, and cycling conditions on the average stresses in the formed oxide scales after cooling. The oxide scale thicknesses were determined by SEM image analyses and information about the stresses were acquired by photo-stimulated luminescence-spectroscopy. Additionally, the scale thickness dependent stress fields were calculated in finite-element analyses including approximation functions for the surface roughness derived on the basis of profilometry data. The evolution of the average residual stress as a function of oxide scale thickness was subjectmore » to stochastic fluctuations predominantly caused by local scale spallations. In comparison to the supplemental modeling results, thermal stresses due to mismatch of thermal expansion coefficients are identified as the main contribution to the residual stresses. Finally, the theoretical results emphasize that analyses of spectroscopic data acquired for average stress investigations of alumina scales rely on detailed information about microstructural features.« less

  18. Effects of thermal cycling parameters on residual stresses in alumina scales of CoNiCrAlY and NiCoCrAlY bond coats

    SciTech Connect

    Nordhorn, Christian; Mücke, Robert; Unocic, Kinga A.; Lance, Michael J.; Pint, Bruce A.; Vaßen, Robert

    2014-08-20

    In this paper, furnace cycling experiments were performed on free-standing high-velocity oxygen-fuel bond coat samples to investigate the effect of material composition, surface texture, and cycling conditions on the average stresses in the formed oxide scales after cooling. The oxide scale thicknesses were determined by SEM image analyses and information about the stresses were acquired by photo-stimulated luminescence-spectroscopy. Additionally, the scale thickness dependent stress fields were calculated in finite-element analyses including approximation functions for the surface roughness derived on the basis of profilometry data. The evolution of the average residual stress as a function of oxide scale thickness was subject to stochastic fluctuations predominantly caused by local scale spallations. In comparison to the supplemental modeling results, thermal stresses due to mismatch of thermal expansion coefficients are identified as the main contribution to the residual stresses. Finally, the theoretical results emphasize that analyses of spectroscopic data acquired for average stress investigations of alumina scales rely on detailed information about microstructural features.

  19. Development of a new diabetes medication self-efficacy scale and its association with both reported problems in using diabetes medications and self-reported adherence

    PubMed Central

    Sleath, Betsy; Carpenter, Delesha M; Blalock, Susan J; Davis, Scott A; Hickson, Ryan P; Lee, Charles; Ferreri, Stefanie P; Scott, Jennifer E; Rodebaugh, Lisa B; Cummings, Doyle M

    2016-01-01

    Background Although there are several different general diabetes self-efficacy scales, there is a need to develop a self-efficacy scale that providers can use to assess patient’s self-efficacy regarding medication use. The purpose of this study was to: 1) develop a new diabetes medication self-efficacy scale and 2) examine how diabetes medication self-efficacy is associated with patient-reported problems in using diabetes medications and self-reported adherence. Patients and methods Adult English-speaking patients with type 2 diabetes were recruited from a family medicine clinic and a pharmacy in Eastern North Carolina, USA. The patients were eligible if they reported being nonadherent to their diabetes medicines on a visual analog scale. Multivariable regression was used to examine the relationship between self-efficacy and the number of reported diabetes medication problems and adherence. Results The diabetes medication self-efficacy scale had strong reliability (Cronbach’s alpha =0.86). Among a sample (N=51) of mostly African-American female patients, diabetes medication problems were common (6.1±3.1) and a greater number of diabetes medications were associated with lower medication adherence (odds ratio: 0.35; 95% confidence interval: 0.13, 0.89). Higher medication self-efficacy was significantly related to medication adherence (odds ratio: 1.17; 95% confidence interval: 1.05, 1.30) and inversely related to the number of self-reported medication problems (β=−0.13; P=0.006). Conclusion Higher diabetes medication self-efficacy was associated with fewer patient-reported medication problems and better medication adherence. Assessing medication-specific self-efficacy may help to identify medication-related problems that providers can help the patients address, potentially improving adherence and patient outcomes. PMID:27354769

  20. Influence of small Pt additions on Al/sub 2/O/sub 3/ scale adherence

    SciTech Connect

    Allam, I.M.; Akuezue, H.C.; Whittle, D.P.

    1980-01-01

    The effects of small Pt additions (1 or 3 wt %) on the oxidation behavior of Co-10Cr-11Al and a similar alloy containing Hf have been studied. An intermetallic phase was present in the alloy containing Hf and Pt but not in that containing Pt alone. The size and distribution of the intermetallic was comparable to that of similar alloys containing oxide dispersions produced by a controlled internal oxidation treatment. As a consequence it promoted the formation of inwardly growing Al/sub 2/O/sub 3/ pegs that helped key the surface scale to the substrate and improve the scale-metal adhesion in both isothermal and cyclic oxidation tests. The improvement in overall oxidation resistance relative to an addition-free alloy was considerable, and similar to that of the best oxide dispersion-containing alloys.

  1. Reliability and validity of a new Medication Adherence Rating Scale (MARS) for the psychoses.

    PubMed

    Thompson, K; Kulkarni, J; Sergejew, A A

    2000-05-05

    Medication compliance is one of the foremost problems affecting neuroleptic efficacy in psychiatric patients. To date, compliancy has most commonly been assessed with the Drug Attitude Inventory (DAI) developed by Hogan et al. (Hogan, T.P., Awad, A.G., Eastwood, R., 1983. A self-report scale predictive of drug compliance in schizophrenics: reliability and discriminative validity. Psychol. Med. 13, 177-183). The present study identified several deficiencies in the DAI. Using the partial credit version of the Item Response Theory measurement model, the DAI was refined with the aim of greater validity and clinical utility. The new inventory was administered to 66 patients, the majority of whom were diagnosed with schizophrenia. When available, lithium levels and carer ratings of compliance were also recorded and used to verify compliancy. The new inventory appears to be a valid and reliable measure of compliancy for psychoactive medications.

  2. Reconciling in vivo and in vitro kinetics of the polymorphic transformation in zirconia-toughened alumina for hip joints: III. Molecular scale mechanisms.

    PubMed

    Pezzotti, Giuseppe; Bal, B Sonny; Zanocco, Matteo; Marin, Elia; Sugano, Nobuhiko; McEntire, Bryan J; Zhu, Wenliang

    2017-02-01

    Understanding the intrinsic reason(s) for the enhanced tetragonal to monoclinic (t→m) polymorphic phase transformation observed on metal-stained surfaces of zirconia-toughened alumina (ZTA) requires detailed knowledge of off-stoichiometry reactions at the molecular scale. In this context, knowledge of the mechanism(s) for oxygen vacancy creation or annihilation at the material surface is a necessary prerequisite. The crucial aspect of the surface destabilization phenomenon, namely the availability of electrons and holes that allow for vacancy creation/annihilation, is elucidated in this paper. Metal-enhanced alterations of the oxygen sublattice in both Al2O3 and ZrO2 of the ZTA composite play a decisive role in accelerating the polymorphic transformation. According to spectroscopic evidences obtained through nanometer-scale analyses, enhanced annihilation of oxygen vacancies triggers polymorphic transformation in ZrO2 near the metal stain, while the overall Al2O3 lattice tends to dehydroxylate by forming oxygen vacancies. A mechanism for chemically driven "reactive metastability" is suggested, which results in accelerating the polymorphic transformation. The Al2O3 matrix is found to play a key-role in the ZrO2 transformation process, with unambiguous confirmation of oxygen and hydrogen transport at the material surface. It is postulated that this transport is mediated by migration of dissociated O and H elements at the surface of the stained transition metal as they become readily available by the thermally activated surrounding.

  3. Reliability and validity of the Chinese version of the HIV Treatment Adherence Self-Efficacy Scale in mainland China.

    PubMed

    Sun, Liang; Yang, Shu-Min; Wu, Hui; Chen, Bing; Wang, Chong-Jian; Li, Xiao-Fang

    2016-10-12

    The aim of this study was to translate the HIV Treatment Adherence Self-Efficacy Scale (HIV-ASES) and evaluate its reliability and validity in people living with HIV (PLWHIV) in mainland China. The original HIV-ASES was translated from English into Chinese and adapted for cultural context according to cross-cultural adaptation guidelines. A cross-sectional survey investigating 1742 PLWHIV receiving antiretroviral treatment was conducted. Exploratory factor analysis with varimax rotation confirmed the presence of two factors with an accumulated contribution rate of 58.357%. Furthermore, confirmatory factor analysis revealed the model's goodness-of-fit index. The comparative fit index was greater than 0.9 and the overall efficacy of the model was satisfactory. The Cronbach α coefficient of the questionnaire was 0.876 (95% CI: 0.868-0.885), and the correlation coefficient of each item and the total was 0.536-0.660 (P < 0.01). The Chinese version of the HIV-ASES has high reliability and validity; however, the individual item requires some adjustment.

  4. Effect of mineral surface properties (alumina, kaolinite) on the sorptive fractionation mechanisms of soil fulvic acids: Molecular-scale ESI-MS studies

    NASA Astrophysics Data System (ADS)

    Fleury, Guillaume; Del Nero, Mirella; Barillon, Rémi

    2017-01-01

    We addressed the effects of mineral surface properties (kaolinite versus Al-oxide) on the sorption-driven fractionation of a soil fulvic acid (FA) at acidic pH, mainly by means of ESI(-)-FTMS analysis of initial and supernatant solutions of FA sorption batch experiments. The MS data provided clear molecular-scale evidence of distinct mechanisms and molecular parameters controlling the FA fractionation upon its sorption on clay and oxide surfaces, respectively. Identification of sorbing and not-sorbing FA compounds in kaolinite-solution systems revealed a weak fractionation among members of sbnd CO2 series of aliphatics or not-condensed aromatics (NCAs) at pH 3.8, and almost no sorption of poorly-oxygenated polycyclic aromatic compounds (PACs) and NCAs. This first molecular-scale description of a FA fractionation in a clay-solution system suggests that H-bonding with low affinity sites (aluminol/silanol) on the basal planes of the clay particles is the main mechanism of sorption. Due to the predominance of such weak and poorly-selective mechanism, the sorption of aliphatic and NCA molecules bearing oxygenated functionalities was prevented at pH 5, due to dissolved Al competing successfully for their coordination. In contrast, a strong FA fractionation was observed onto alumina, with a preferential retention of PACs and highly-oxygenated aliphatics and NCAs. The major part of the poorly oxygenated aliphatics was left in solution. The sorption degree of NCAs and aliphatics was strongly correlated with molecular acidity. For PACs and poorly-oxygenated NCAs, the sorption was driven by reactions of surface ligand exchange (for the most oxygenated compounds) or by hydrophobic interactions (for the least oxygenated compounds).

  5. Bauxite and alumina

    USGS Publications Warehouse

    Bray, E.L.

    2009-01-01

    The article provides information on bauxite and alumina mining. U.S. states like Alabama, Arkansas and Georgia produced small amounts of bauxite and bauxitic clays for nonmetallurgical uses. Total metallurgical-grade bauxite imports in 2008 is cited. The leading suppliers of bauxite to the U.S. are Jamaica, Guinea and Brazil. The estimated domestic production of alumina in 2008 is mentioned. It also discusses consumption and prices of both bauxite and alumina.

  6. Rethinking adherence.

    PubMed

    Steiner, John F

    2012-10-16

    In 2012, the Centers for Medicare & Medicaid Services (CMS) will introduce measures of adherence to oral hypoglycemic, antihypertensive, and cholesterol-lowering drugs into its Medicare Advantage quality program. To meet these quality goals, delivery systems will need to develop and disseminate strategies to improve adherence. The design of adherence interventions has too often been guided by the mistaken assumptions that adherence is a single behavior that can be predicted from readily available patient characteristics and that individual clinicians alone can improve adherence at the population level.Effective interventions require recognition that adherence is a set of interacting behaviors influenced by individual, social, and environmental forces; adherence interventions must be broadly based, rather than targeted to specific population subgroups; and counseling with a trusted clinician needs to be complemented by outreach interventions and removal of structural and organizational barriers. To achieve the adherence goals set by CMS, front-line clinicians, interdisciplinary teams, organizational leaders, and policymakers will need to coordinate efforts in ways that exemplify the underlying principles of health care reform.

  7. Large Scale Laser Crystallization of Solution-based Alumina-doped Zinc Oxide (AZO) Nanoinks for Highly Transparent Conductive Electrode

    PubMed Central

    Nian, Qiong; Callahan, Michael; Saei, Mojib; Look, David; Efstathiadis, Harry; Bailey, John; Cheng, Gary J.

    2015-01-01

    A new method combining aqueous solution printing with UV Laser crystallization (UVLC) and post annealing is developed to deposit highly transparent and conductive Aluminum doped Zinc Oxide (AZO) films. This technique is able to rapidly produce large area AZO films with better structural and optoelectronic properties than most high vacuum deposition, suggesting a potential large-scale manufacturing technique. The optoelectronic performance improvement attributes to UVLC and forming gas annealing (FMG) induced grain boundary density decrease and electron traps passivation at grain boundaries. The physical model and computational simulation developed in this work could be applied to thermal treatment of many other metal oxide films. PMID:26515670

  8. Large Scale Laser Crystallization of Solution-based Alumina-doped Zinc Oxide (AZO) Nanoinks for Highly Transparent Conductive Electrode.

    PubMed

    Nian, Qiong; Callahan, Michael; Saei, Mojib; Look, David; Efstathiadis, Harry; Bailey, John; Cheng, Gary J

    2015-10-30

    A new method combining aqueous solution printing with UV Laser crystallization (UVLC) and post annealing is developed to deposit highly transparent and conductive Aluminum doped Zinc Oxide (AZO) films. This technique is able to rapidly produce large area AZO films with better structural and optoelectronic properties than most high vacuum deposition, suggesting a potential large-scale manufacturing technique. The optoelectronic performance improvement attributes to UVLC and forming gas annealing (FMG) induced grain boundary density decrease and electron traps passivation at grain boundaries. The physical model and computational simulation developed in this work could be applied to thermal treatment of many other metal oxide films.

  9. Large Scale Laser Crystallization of Solution-based Alumina-doped Zinc Oxide (AZO) Nanoinks for Highly Transparent Conductive Electrode

    NASA Astrophysics Data System (ADS)

    Nian, Qiong; Callahan, Michael; Saei, Mojib; Look, David; Efstathiadis, Harry; Bailey, John; Cheng, Gary J.

    2015-10-01

    A new method combining aqueous solution printing with UV Laser crystallization (UVLC) and post annealing is developed to deposit highly transparent and conductive Aluminum doped Zinc Oxide (AZO) films. This technique is able to rapidly produce large area AZO films with better structural and optoelectronic properties than most high vacuum deposition, suggesting a potential large-scale manufacturing technique. The optoelectronic performance improvement attributes to UVLC and forming gas annealing (FMG) induced grain boundary density decrease and electron traps passivation at grain boundaries. The physical model and computational simulation developed in this work could be applied to thermal treatment of many other metal oxide films.

  10. Story-based scales: development and validation of questionnaires to measure subjective health status and cultural adherence in British Bangladeshis with diabetes.

    PubMed

    Greenhalgh, Trisha; Chowdhury, Mu'min; Wood, Gary W

    2006-11-01

    Questionnaires that measure subjective health status are increasingly used in clinical trials. But scales based on the quantification of subjective traits ("rate your feelings on a scale of 1 to 5") and initially developed in western population samples may not be valid for use in minority ethnic groups, even if accurately translated. The measurement of cultural adaptation and assimilation in immigrant groups is important for health research but has well documented methodological challenges. The aim of this study was to develop valid and reliable questionnaires to measure subjective health status and cultural adherence in a minority ethnic group, using the story as the unit of inquiry. The design was a multi-phase study involving (a) narrative interview, (b) vignette construction, (c) questionnaire development, and (d) questionnaire validation in relation to two scales (well-being and cultural adherence) in British Bangladeshis with diabetes. Using data from in-depth narrative interviews (i.e., a non-directive research technique in which the participant is invited to "tell me the story about your diabetes, starting with when you first noticed anything wrong", and the only prompts used are "tell me more about that" or "what happened next?"; Greenhalgh, Helman, & Chowdhury, 1998; Muller, 1999), we constructed culturally congruent vignettes to depict different subjective health states and behaviours. We refined these items in focus group interviews and validated the instruments on 98 Bangladeshi participants, randomly sampled from GP diabetes registers in inner London and interviewed by a Bangladeshi anthropologist. We used factor analysis to explore the underlying structure in the responses to questionnaire items, plus Cronbach alpha tests to measure internal consistency of scales. The questionnaires were acceptable and credible to Bangladeshi participants with diabetes. Ninety of 98 participants were able and willing to complete them with interviewer assistance

  11. Microporous alumina ceramic membranes

    DOEpatents

    Anderson, M.A.; Guangyao Sheng.

    1993-05-04

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  12. Microporous alumina ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  13. Reliability and known-group validity of the Arabic version of the 8-item Morisky Medication Adherence Scale among type 2 diabetes mellitus patients.

    PubMed

    Ashur, S T; Shamsuddin, K; Shah, S A; Bosseri, S; Morisky, D E

    2015-12-13

    No validation study has previously been made for the Arabic version of the 8-item Morisky Medication Adherence Scale (MMAS-8(©)) as a measure for medication adherence in diabetes. This study in 2013 tested the reliability and validity of the Arabic MMAS-8 for type 2 diabetes mellitus patients attending a referral centre in Tripoli, Libya. A convenience sample of 103 patients self-completed the questionnaire. Reliability was tested using Cronbach alpha, average inter-item correlation and Spearman-Brown coefficient. Known-group validity was tested by comparing MMAS-8 scores of patients grouped by glycaemic control. The Arabic version showed adequate internal consistency (α = 0.70) and moderate split-half reliability (r = 0.65). Known-group validity was supported as a significant association was found between medication adherence and glycaemic control, with a moderate effect size (ϕc = 0.34). The Arabic version displayed good psychometric properties and could support diabetes research and practice in Arab countries.

  14. Reuse of activated alumina

    SciTech Connect

    Hobensack, J.E.

    1991-12-31

    Activated alumina is used as a trapping media to remove trace quantities of UF{sub 6} from process vent streams. The current uranium recovery method employs concentrated nitric acid which destroys the alumina pellets and forms a sludge which is a storage and disposal problem. A recently developed technique using a distilled water rinse followed by three dilute acid rinses removes on average 97% of the uranium, and leaves the pellets intact with crush strength and surface area values comparable with new material. Trapping tests confirm the effectiveness of the recycled alumina as UF{sub 6} trapping media.

  15. Transcultural adaptation and initial validation of Brazilian-Portuguese version of the Basel assessment of adherence to immunosuppressive medications scale (BAASIS) in kidney transplants

    PubMed Central

    2013-01-01

    Background Transplant recipients are expected to adhere to a lifelong immunosuppressant therapeutic regimen. However, nonadherence to treatment is an underestimated problem for which no properly validated measurement tool is available for Portuguese-speaking patients. We aimed to initially validate the Basel Assessment of Adherence to Immunosuppressive Medications Scale (BAASIS®) to accurately estimate immunosuppressant nonadherence in Brazilian transplant patients. Methods The BAASIS® (English version) was transculturally adapted and its psychometric properties were assessed. The transcultural adaptation was performed using the Guillemin protocol. Psychometric testing included reliability (intraobserver and interobserver reproducibility, agreement, Kappa coefficient, and the Cronbach’s alpha) and validity (content, criterion, and construct validities). Results The final version of the transculturally adapted BAASIS® was pretested, and no difficulties in understanding its content were found. The intraobserver and interobserver reproducibility variances (0.007 and 0.003, respectively), the Cronbach’s alpha (0.7), Kappa coefficient (0.88) and the agreement (95.2%) suggest accuracy, preciseness and reliability. For construct validity, exploratory factorial analysis demonstrated unidimensionality of the first three questions (r = 0.76, r = 0.80, and r = 0.68). For criterion validity, the adapted BAASIS® was correlated with another self-report instrument, the Measure of Adherence to Treatment, and showed good congruence (r = 0.65). Conclusions The BAASIS® has adequate psychometric properties and may be employed in advance to measure adherence to posttransplant immunosuppressant treatments. This instrument will be the first one validated to use in this specific transplant population and in the Portuguese language. PMID:23692889

  16. Reliability and validity of Arabic translation of Medication Adherence Report Scale (MARS) and Beliefs about Medication Questionnaire (BMQ)–specific for use in children and their parents

    PubMed Central

    Alsous, Mervat; Alhalaiqa, Fadwa; Abu Farha, Rana; Abdel Jalil, Mariam; McElnay, James; Horne, Robert

    2017-01-01

    Objectives to evaluate the reliability and discriminant validity of Arabic translation of the Medication Adherence Report Scale (MARS) and the Beliefs about Medication Questionnaire-specific (BMQ-specific). Methods Having developed Arabic translations of the study instruments, a cross-sectional study was carried out between March and October 2015 in two multidisciplinary governmental hospitals in Jordan. An expert panel monitored the forward and backward translation of the MARS and BMQ. Standard Arabic was used (with no specific dialect inclusion) to allow greater generalisability across Arabic speaking countries. Once the Arabic translations of the questionnaires were developed they were tested for consistency, validity and reliability on a group of children with chronic diseases and their parents. Results A total of 258 parents and 208 children were included in the study. The median age of participated children and parents was 15 years and 42 years respectively. Principle component analysis of all questionnaires indicated that all had good construct validity as they clearly measured one construct. The questionnaires were deemed reliable based on the results of Cronbach alpha coefficient. Furthermore, reliability of the questionnaires was demonstrated by test-retest intraclass correlation coefficients (ICC) which ranged from good to excellent for all scales (ICC>0.706). The Pearson correlation coefficient ranged from 0.546–0.805 for the entire sample which indicated a significant moderate to strong positive correlation between MARS and BMQ items at time 1 and 2. Reported adherence was greater than 59% using MARS-children and MARS-parents scales, and was correlated with beliefs in necessity and independent of the concerns regarding medications. Conclusion The Arabic translations of both BMQ and MARS for use in children and their parents have good internal consistency and proved to be valid and reliable tools that can be used by researchers in clinical practice to

  17. Characterization of Alumina Interfaces in TBC Systems

    SciTech Connect

    Pint, Bruce A; More, Karren Leslie

    2009-01-01

    Interfacial segregants in thermally grown {alpha}-Al{sub 2}O{sub 3} scales formed during high temperature exposure of thermal barrier coating systems reflect the oxygen-active dopants present in the bond coating and substrate, such as Y and Hf. These dopants diffuse outward and segregate to the substrate-alumina interface and the alumina grain boundaries. Related studies suggest that these segregants affect the growth and mechanical properties of the alumina-scale; however, the characterization of segregation in alumina formed on coated superalloy systems has been limited. Segregation examples evaluated using analytical transmission electron microscopy are given from traditional Pt-modified aluminide coatings and newer Pt diffusion coatings. Model systems are used to illustrate that grain boundary segregants on the columnar alumina boundaries are not because of the reverse diffusion of cations from the Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} top coating, and that interstitial elements in the substrate likely affect the outward flux of cation dopants. The dynamic nature of this segregation and oxygen-potential gradient-driven diffusion is discussed in light of observations of substrate dopant and interstitial contents affecting coating performance.

  18. Alumina fiber strength improvement

    NASA Technical Reports Server (NTRS)

    Pepper, R. T.; Nelson, D. C.

    1982-01-01

    The effective fiber strength of alumina fibers in an aluminum composite was increased to 173,000 psi. A high temperature heat treatment, combined with a glassy carbon surface coating, was used to prevent degradation and improve fiber tensile strength. Attempts to achieve chemical strengthening of the alumina fiber by chromium oxide and boron oxide coatings proved unsuccessful. A major problem encountered on the program was the low and inconsistent strength of the Dupont Fiber FP used for the investigation.

  19. Bauxite and alumina

    USGS Publications Warehouse

    Bray, E.L.

    2011-01-01

    The article discusses the latest developments in the bauxite and alumina industry, particularly in the U.S., as of June 2011. It claims that the U.S. mainly relies on imports for its bauxite consumption. Several states, including Alabama, Arkansas and Georgia, however, produce small amounts of bauxite and bauxitic clays for nonmetallurgical purposes. The major exporters of alumina to the U.S. include Australia, Brazil and Jamaica.

  20. Laser Surface Treatment of Sintered Alumina

    NASA Astrophysics Data System (ADS)

    Hagemann, R.; Noelke, C.; Kaierle, S.; Wesling, V.

    Sintered alumina ceramics are used as refractory materials for industrial aluminum furnaces. In this environment the ceramic surface is in permanent contact with molten aluminum resulting in deposition of oxidic material on its surface. Consequently, a lower volume capacity as well as thermal efficiency of the furnaces follows. To reduce oxidic adherence of the ceramic material, two laser-based surface treatment processes were investigated: a powder- based single-step laser cladding and a laser surface remelting. Main objective is to achieve an improved surface quality of the ceramic material considering the industrial requirements as a high process speed.

  1. Adherence to antiepilepsy drug therapy.

    PubMed

    Faught, Edward

    2012-11-01

    Adherence to antiepilepsy drug (AED) therapy is critical for effective disease management, yet adherence and persistence rates are low due to several barriers. The definitions of adherence (80% rate of total pills taken, medication possession ratio, and days covered by prescriptions filled) and methods of measurement (patient self-reports, serum drug levels, pill counts, electronic bottle tops, and reviews of pharmacy records) are not without limitations, and their applicability to epilepsy is not clear. The use of simple adherence scales during office visits can provide an overall impression of a patient's adherence and can serve as a basis for practitioner-patient dialog. Efforts to improve adherence should focus on provider and healthcare system determinants versus those focused only on the patient. These interventions include non-judgmental communication, patient education, simplification of the dosage regimen with once-daily therapies, and the use of patient reminders.

  2. Yttrium influence on the alumina growth mechanism on an FeCr23Al5 alloy

    NASA Astrophysics Data System (ADS)

    Huntz, A. M.; Abderrazik, G. Ben; Moulin, G.; Young, E. W. A.; De Wit, J. H. W.

    1987-07-01

    The mechanism by which yttrium modifies alumina growth was studied by comparing the behaviour of a high purity FeCr23Al5 alloy, either undoped or Y doped by implantation. By combining several techniques, in particular XPS, nuclear reaction analyses and electrochemical measurements, it is shown that the growth of Al2O3 scales on pure samples is mainly ensured by aluminum short-circuit diffusion. The presence of yttrium promotes the oxygen diffusion along grain boundaries, while retarding Al short-circuit diffusion and increasing Al lattice diffusion. From this growth mechanism with both cationic amd anionic diffusion along different paths, suggestions for the improvement of scale adherence due to yttrium are proposed. The simultaneous study of C- and Y-doped samples indicates that synergetic effects occur.

  3. Optimizing adherence to antiretroviral therapy

    PubMed Central

    Sahay, Seema; Reddy, K. Srikanth; Dhayarkar, Sampada

    2011-01-01

    HIV has now become a manageable chronic disease. However, the treatment outcomes may get hampered by suboptimal adherence to ART. Adherence optimization is a concrete reality in the wake of ‘universal access’ and it is imperative to learn lessons from various studies and programmes. This review examines current literature on ART scale up, treatment outcomes of the large scale programmes and the role of adherence therein. Social, behavioural, biological and programme related factors arise in the context of ART adherence optimization. While emphasis is laid on adherence, retention of patients under the care umbrella emerges as a major challenge. An in-depth understanding of patients’ health seeking behaviour and health care delivery system may be useful in improving adherence and retention of patients in care continuum and programme. A theoretical framework to address the barriers and facilitators has been articulated to identify problematic areas in order to intervene with specific strategies. Empirically tested objective adherence measurement tools and approaches to assess adherence in clinical/ programme settings are required. Strengthening of ART programmes would include appropriate policies for manpower and task sharing, integrating traditional health sector, innovations in counselling and community support. Implications for the use of theoretical model to guide research, clinical practice, community involvement and policy as part of a human rights approach to HIV disease is suggested. PMID:22310817

  4. Psychosocial Predictors of Non-Adherence and Treatment Failure in a Large Scale Multi-National Trial of Antiretroviral Therapy for HIV: Data from the ACTG A5175/PEARLS Trial

    PubMed Central

    Safren, Steven A.; Biello, Katie B.; Smeaton, Laura; Mimiaga, Matthew J.; Walawander, Ann; Lama, Javier R.; Rana, Aadia; Nyirenda, Mulinda; Kayoyo, Virginia M.; Samaneka, Wadzanai; Joglekar, Anjali; Celentano, David; Martinez, Ana; Remmert, Jocelyn E.; Nair, Aspara; Lalloo, Umesh G.; Kumarasamy, Nagalingeswaran; Hakim, James; Campbell, Thomas B.

    2014-01-01

    Background PEARLS, a large scale trial of antiretroviral therapy (ART) for HIV (n = 1,571, 9 countries, 4 continents), found that a once-daily protease inhibitor (PI) based regimen (ATV+DDI+FTC), but not a once-daily non-nucleoside reverse transcriptase inhibitor/nucleoside reverse transcriptase inhibitor (NNRTI/NRTI) regimen (EFV+FTC/TDF), had inferior efficacy compared to a standard of care twice-daily NNRTI/NRTI regimen (EFV+3TC/ZDV). The present study examined non-adherence in PEARLS. Methods Outcomes: non-adherence assessed by pill count and by self-report, and time to treatment failure. Longitudinal predictors: regimen, quality of life (general health perceptions  =  QOL-health, mental health  =  QOL-mental health), social support, substance use, binge drinking, and sexual behaviors. “Life-Steps” adherence counseling was provided. Results In both pill-count and self-report multivariable models, both once-a-day regimens had lower levels of non-adherence than the twice-a-day standard of care regimen; although these associations attenuated with time in the self-report model. In both multivariable models, hard-drug use was associated with non-adherence, living in Africa and better QOL-health were associated with less non-adherence. According to pill-count, unprotected sex was associated with non-adherence. According to self-report, soft-drug use was associated with non-adherence and living in Asia was associated with less non-adherence. Both pill-count (HR = 1.55, 95% CI: 1.15, 2.09, p<.01) and self-report (HR = 1.13, 95% CI: 1.08, 1.13, p<.01) non-adherence were significant predictors of treatment failure over 72 weeks. In multivariable models (including pill-count or self-report nonadherence), worse QOL-health, age group (younger), and region were also significant predictors of treatment failure. Conclusion In the context of a large, multi-national, multi-continent, clinical trial there were variations in adherence over time, with more

  5. Alumina Technology Roadmap

    SciTech Connect

    none,

    2002-02-01

    The Alumina Technology Roadmap outlines a comprehensive long-term research and development plan that defines the industry's collective future and establishes a clear pathway forward. It emphasizes twelve high-priority R&D areas deemed most significant in addressing the strategic goals.

  6. Solid Lubricant For Alumina

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Pepper, Stephen V.; Honecy, Frank S.

    1993-01-01

    Outer layer of silver lubricates, while intermediate layer of titanium ensures adhesion. Lubricating outer films of silver deposited on thin intermediate films of titanium on alumina substrates found to reduce sliding friction and wear. Films provide effective lubrication for ceramic seals, bearings, and other hot sliding components in advanced high-temperature engines.

  7. Prediction of alumina penetration

    SciTech Connect

    Mandell, D A

    1993-02-01

    The MESA hydrocode was used to predict two-dimensional tests of L/D 10 and L/D 15 tungsten rods impacting AD 90 alumina with a steel backing. The residual penetration into the steel is the measured quantity in these experiments conducted at the Southwest Research Institute (SWR). The interface velocity as a function of time between an alumina target and a lithium fluoride window, impacted by an alumina disk at velocities between 544 m/s and 2329 m/s, was also predicted. These one-dimensional flyer plate experiments were conducted at Sandia National Laboratories using Coors AD 995 alumina. The material strength and fracture models are important in the prediction of ceramic experiments. The models used in these predictions are discussed. The penetrations in the two-dimensional tests were predicted to 11.4 percent or better. In five of the six experiments, the predicted penetration depth was deeper than the measured value. This trend is expected since the calculation is based on ideal conditions. The results show that good agreement between the 1-D flyer plate data and the MESA predictions exists at the lower impact velocities, but the maximum velocity is overpredicted as the flyer plate velocity increases. At a flyer plate velocity of 2329 m/s the code overpredicted the data by 12.3 percent.

  8. Bauxite and alumina

    USGS Publications Warehouse

    Bray, E.L.

    2010-01-01

    The article reports on the global market performance of bauxite and alumina in 2009 and presents an outlook for their 2010 performance. There were only several U.S. states that could produce bauxite and bauxitic clays including Georgia, Arkansas, and Alabama. The prices for imported refractory-grade calcined bauxite ranged between 426 U.S. dollars and 554 dollars per ton.

  9. Measurement of Psychiatric Treatment Adherence

    PubMed Central

    Sajatovic, Martha; Velligan, Dawn; Weiden, Peter J.; Valenstein, Marcia; Ogedegbe, Gbenga

    2014-01-01

    Objective Nonadherence to medications for mental disorders substantially limits treatment effectiveness and results in higher rates of relapse, hospitalization, and disability. Accurate measurement of medication adherence is important not only in adherence research, but also in clinical trials in which medications are being evaluated, and in clinical practice where failure to detect nonadherence results in premature medication changes, unnecessary polypharmacy, and greater likelihoods of functional deteriorations and hospitalizations. This is a review of psychiatric treatment adherence methods and measures arising from a meeting on “Methodological Challenges in Psychiatric Treatment Adherence Research” held on September 27-28, 2007 in Bethesda, MD and organized by the National Institute of Mental Health (NIMH). Methods This paper reviews the range of modalities currently available for assessing adherence behavior including pill counts, pharmacy records, technology-assisted monitoring, biological assays, and a range of self-report and interviewer-rated scales. Measures of adherence attitudes are also reviewed. Results Each of the adherence measures described are imperfect estimates of actual medication ingestion but each provides informative estimates of adherence or the attitudinal factors associated with adherence. Measure selection depends on a range of factors including the patient sample, the context in which the measure is being used, and the clinical outcomes expected from various levels of nonadherence. The use of multiple measures of adherence is encouraged to balance the limitations of individual measures. Conclusion While adherence assessment has become increasingly sophisticated in recent years there remains a need for refinement and expansion on currently available methods and measures. PMID:21109048

  10. Screen-Cage Ion Plating Of Silver On Polycrystalline Alumina

    NASA Technical Reports Server (NTRS)

    Spalvins, Talivaldis; Sliney, Harold E.; Deadmore, Daniel L.

    1995-01-01

    Screen-cage ion plating (SCIP) cost-effective technique offering high throwing power for deposition of adherent metal films on ceramic substrates. Applies silver films to complexly shaped substrates of polycrystalline alumina. Silver adheres tenaciously and reduces friction. SCIP holds promise for applying lubricating soft metallic films to high-temperature ceramic components of advanced combustion engines. Other potential uses include coating substrates with metal for protection against corrosion, depositing electrical conductors on dielectric substrates, making optically reflective or electrically or thermally conductive surface layers, and applying decorative metal coats to ceramic trophies or sculptures.

  11. [Treatment adherence: a key element].

    PubMed

    Bastida, Guillermo; Sánchez Montes, Cristina; Aguas, Mariam

    2011-12-01

    A substantial percentage of patients fail to follow health professionals' recommendations, which affects the management of chronic diseases, reducing the effectiveness of therapeutic interventions and increasing the costs of the disease. Lack of adherence is a multidimensional phenomenon and is influenced by numerous factors that should be identified. A multiplicity of measures is available to improve adherence, such as simplifying treatment administration, but none of these measures is effective when used alone. One way of tackling lack of adherence is by identifying patients' barriers to medication and involving them in decision making. Ulcerative colitis (UC) poses a risk for lack of treatment adherence. In this disease, poor adherence correlates with poor disease control (drug effectiveness) and with higher costs. As in other chronic diseases, the causes associated with poor adherence are multiple, including psychosocial factors, the physician-patient relationship and patients' prejudices toward medication. A single dose of aminosalycylates (5-ASA) should be recommended, as this dose is as safe and effective as other regimens. However, by itself, this recommendation does not seem to improve adherence. Identifying the scale of the problem and developing strategies to involve the patient in decision making is crucial to improve treatment adherence.

  12. Alumina forming iron base superalloy

    DOEpatents

    Yamamoto, Yukinori; Muralidharan, Govindarajan; Brady, Michael P.

    2014-08-26

    An austenitic stainless steel alloy, consists essentially of, in weight percent 2.5 to 4 Al; 25 to 35 Ni; 12 to 19 Cr; at least 1, up to 4 total of at least one element selected from the group consisting of Nb and Ta; 0.5 to 3 Ti; less than 0.5 V; 0.1 to 1 of at least on element selected from the group consisting of Zr and Hf; 0.03 to 0.2 C; 0.005 to 0.1 B; and base Fe. The weight percent Fe is greater than the weight percent Ni. The alloy forms an external continuous scale including alumina, and contains coherent precipitates of .gamma.'-Ni.sub.3Al, and a stable essentially single phase FCC austenitic matrix microstructure. The austenitic matrix is essentially delta-ferrite-free and essentially BCC-phase-free.

  13. Deformation Behaviour of Coarse Grain Alumina under Shock Loading

    NASA Astrophysics Data System (ADS)

    Gupta, Satish

    2013-06-01

    To develop better understanding of the shock wave induced deformation behavior of coarse grain alumina ceramics, and for measurement of its Hugoniot Elastic Limit (HEL), in-situ and recovery gas gun experiments have been carried out on coarse grain alumina (grain size ~ 10 μm), prepared in the form of discs (>99.9% TMD) by pressure-less sintering of alpha alumina powder at 1583 K. The HEL value of 1.9 GPa has been determined from the kink in the pressure history recorded using piezoresistance gauge and also from the free surface velocity history of the sample shocked to 9 GPa. The nano-indentation measurements on the alumina samples shocked to 6.5 GPa showed hardness value 15% lower than 21.3 GPa for unshocked alumina, and strong Indentation Size Effect (ISE); the hardness value was still lower and the ISE was stronger for the sample shocked to 12 GPa. The XRD measurements showed reduced particle size and increased microstrains in the shocked alumina fragments. SEM, FESEM and TEM measurements on shock treated samples showed presence of grain localized micro- and nano-scale deformations, micro-cleavages, grain-boundary microcracks, extensive shear induced deformations, and localized micro-fractures, etc. These observations led to the development of a qualitative model for the damage initiation and its subsequent growth mechanisms in shocked alumina. The work performed in collaboration with K.D. Joshi of BARC and A.K. Mukhopadhyay of CGCRI.

  14. [Cross-cultural adaptation and psychometric tests of a self-efficacy scale and an adherence scale for French adolescents with Type 1 diabetes

    PubMed

    Colson, Sébastien; Coté, José; Collombier, Madeleine; Debout, Christophe; Bonnel, Galadriel; Reynaud, Rachel; Lagouanelle-Simeoni, Marie-Claude

    2016-12-01

    Introduction : many structured educational programs, using the concept of self-efficacy, have been studied in English-speaking countries. Background : tools were developed in English to assess this concept along with treatment adherence. However, there seems to be no French version of these tools in scientific literature. Aim : to adapt the tools to the French language and to test the psychometric properties of the Self-Efficacy for Diabetes Self-Management (SEDM) and the Diabetes Self-Management Profile (DSMP). Methods : a cross-cultural adaptation of the SEDM and DSMP in French was performed. The psychometric properties were tested in a pilot study that took place between January 1st and December 31st, 2015. Results : Cronbach’s alpha coefficient of SEDM in French was 0.84, test-retest reliability 0.80 and sensitivity to change was moderate. The Cronbach’s alpha and sensitivity to change of the French DSMP were low, and the test-retest was 0.71. Discussion and conclusions : the first results of the psychometric properties of French SEDM were rather encouraging. The use of the French version of DSMP seems compromised in terms of psychometric properties and the opinion of the participants.

  15. Validation of Malaysian Versions of Perceived Diabetes Self-Management Scale (PDSMS), Medication Understanding and Use Self-Efficacy Scale (MUSE) and 8-Morisky Medication Adherence Scale (MMAS-8) Using Partial Credit Rasch Model

    PubMed Central

    Al Abboud, Safaa Ahmed; Ahmad, Sohail; Bidin, Mohamed Badrulnizam Long

    2016-01-01

    Introduction The Diabetes Mellitus (DM) is a common silent epidemic disease with frequent morbidity and mortality. The psychological and psychosocial health factors are negatively influencing the glycaemic control in diabetic patients. Therefore, various questionnaires were developed to address the psychological and psychosocial well-being of the diabetic patients. Most of these questionnaires were first developed in English and then translated into different languages to make them useful for the local communities. Aim The main aim of this study was to translate and validate the Malaysian versions of Perceived Diabetes Self-Management Scale (PDSMS), Medication Understanding and Use Self-Efficacy Scale (MUSE), and to revalidate 8-Morisky Medication Adherence Scale (MMAS-8) by Partial Credit Rasch Model (Modern Test Theory). Materials and Methods Permission was obtained from respective authors to translate the English versions of PDSMS, MUSE and MMAS-8 into Malay language according to established standard international translation guidelines. In this cross-sectional study, 62 adult DM patients were recruited from Hospital Kuala Lumpur by purposive sampling method. The data were extracted from the self-administered questionnaires and entered manually in the Ministeps (Winsteps) software for Partial Credit Rasch Model. The item and person reliability, infit/outfit Z-Standard (ZSTD), infit/outfit Mean Square (MNSQ) and point measure correlation (PTMEA Corr) values were analysed for the reliability analyses and construct validation. Results The Malay version of PDSMS, MUSE and MMAS-8 found to be valid and reliable instrument for the Malaysian diabetic adults. The instrument showed good overall reliability value of 0.76 and 0.93 for item and person reliability, respectively. The values of infit/outfit ZSTD, infit/outfit MNSQ, and PTMEA Corr were also within the stipulated range of the Rasch Model proving the valid item constructs of the questionnaire. Conclusion The

  16. Computational modeling of adherent cell growth in a hollow-fiber membrane bioreactor for large-scale 3-D bone tissue engineering.

    PubMed

    Mohebbi-Kalhori, Davod; Behzadmehr, Amin; Doillon, Charles J; Hadjizadeh, Afra

    2012-09-01

    The use of hollow-fiber membrane bioreactors (HFMBs) has been proposed for three-dimensional bone tissue growth at the clinical scale. However, to achieve an efficient HFMB design, the relationship between cell growth and environmental conditions must be determined. Therefore, in this work, a dynamic double-porous media model was developed to determine nutrient-dependent cell growth for bone tissue formation in a HFMB. The whole hollow-fiber scaffold within the bioreactor was treated as a porous domain in this model. The domain consisted of two interpenetrating porous regions, including a porous lumen region available for fluid flow and a porous extracapillary space filled with a collagen gel that contained adherent cells for promoting long-term growth into tissue-like mass. The governing equations were solved numerically and the model was validated using previously published experimental results. The contributions of several bioreactor design and process parameters to the performance of the bioreactor were studied. The results demonstrated that the process and design parameters of the HFMB significantly affect nutrient transport and thus cell behavior over a long period of culture. The approach presented here can be applied to any cell type and used to develop tissue engineering hollow-fiber scaffolds.

  17. High Temperature Stability of Potassium Beta Alumina

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Kisor, A.; Ryan, M. A.

    1996-01-01

    None. From Objectives section: Evaluate the stability of potassium beta alumina under potassium AMTEC operating conditions. Evaluate the stability regime in which potassium beta alumina can be fabricated.

  18. Mesoscale Modelling of the Response of Aluminas

    SciTech Connect

    Bourne, N. K.

    2006-07-28

    The response of polycrystalline alumina to shock is not well addressed. There are several operating mechanisms that only hypothesized which results in models which are empirical. A similar state of affairs in reactive flow modelling led to the development of mesoscale representations of the flow to illuminate operating mechanisms. In this spirit, a similar effort is undergone for a polycrystalline alumina. Simulations are conducted to observe operating mechanisms at the micron scale. A method is then developed to extend the simulations to meet response at the continuum level where measurements are made. The approach is validated by comparison with continuum experiments. The method and results are presented, and some of the operating mechanisms are illuminated by the observed response.

  19. Bauxite Mining and Alumina Refining

    PubMed Central

    Frisch, Neale; Olney, David

    2014-01-01

    Objective: To describe bauxite mining and alumina refining processes and to outline the relevant physical, chemical, biological, ergonomic, and psychosocial health risks. Methods: Review article. Results: The most important risks relate to noise, ergonomics, trauma, and caustic soda splashes of the skin/eyes. Other risks of note relate to fatigue, heat, and solar ultraviolet and for some operations tropical diseases, venomous/dangerous animals, and remote locations. Exposures to bauxite dust, alumina dust, and caustic mist in contemporary best-practice bauxite mining and alumina refining operations have not been demonstrated to be associated with clinically significant decrements in lung function. Exposures to bauxite dust and alumina dust at such operations are also not associated with the incidence of cancer. Conclusions: A range of occupational health risks in bauxite mining and alumina refining require the maintenance of effective control measures. PMID:24806720

  20. HIV Medication Adherence

    MedlinePlus

    HIV Treatment HIV Medication Adherence (Last updated 3/2/2017; last reviewed 3/2/2017) Key Points Medication adherence means sticking firmly to ... Before and After Starting HIV Medicines . What is medication adherence? Adherence means “to stick firmly.” So for ...

  1. Branchy alumina nanotubes

    NASA Astrophysics Data System (ADS)

    Zou, Jianping; Pu, Lin; Bao, Ximao; Feng, Duan

    2002-02-01

    Branchy alumina nanotubes (bANTs) have been shown to exist in aluminum oxide. Electron-beam evaporated 400 nm Al film on Si substrate is stepwise anodized in dilute sulfuric acid under the constant dc voltage 40 V at 10.0 °C. This electrochemical-anodizing route resulted in the formation of individual bANTs. Transmission electron microscopy showed that the length of the bANTs was around 450 nm, and the inner diameter was around 10-20 nm. We deduced that the bANTs, the completely detached multibranchy cells of anodic porous alumina (APA) film, should be evolved from the stagnant cells of the APA mother film. The bANTs may be used as templates in fabrication of individual branchy nanoscale cables, jacks, and heterojunctions. The proposed formation mechanisms of the bANTs and the stagnant cells should give some insights into the long-standing problem of APA film, i.e., the self-ordering mechanism of the cells arrangement in porous anodization of aluminum.

  2. Production and characterization of alumina-titania biocomposite

    NASA Astrophysics Data System (ADS)

    Cetiner, B. N.; Erkmen, Z. E.

    2015-03-01

    Alumina is a biomaterial of choice for more than 20 years due to its high hardness accompanied by low friction, wear and inertness to in vivo environment. It has been reported that titanium oxidized to the rutile phase is bioactive. This is a property discovered for certain ceramics such as Bioglass and sintered hydroxylapatite (HA). But the combination of alumina and titania forming tialite (Aluminium titanate-50 mol % Al2O3 and 50 mol % TiO2) is a new challenge. In this work we made firstly the beneficiation of the Seydişehir alumina by leaching it in the acidic solution "the Aqua Regia" followed by preparation of batches containing 2,5 wt %, 3,5 wt % and 4,5 wt % of MgO as the sintering aid, 1 wt % of SiO2 and the balance; the alumina and titania powder mixture (1:1 mole). After sintering these batches at 1600°C for about 12 h, their mechanical properties (the compression and hardness testings) and phase ratios (the XRD analysis) were analyzed and compared with the control group containing the laboratory scale alumina instead of the Seydişehir alumina. Following the characterization (the SEM and the EDS analysis) of the substrate material, the comparison of two different materials was carried out.

  3. Osseointegration of alumina bioceramic granules: A comparative experimental study

    NASA Astrophysics Data System (ADS)

    Rerikh, V. V.; Avetisyan, A. R.; Zaydman, A. M.; Anikin, K. A.; Bataev, V. A.; Nikulina, A. A.; Sadovoy, M. A.; Aronov, A. M.; Semantsova, E. S.

    2016-08-01

    To perform a comparative analysis of osseointegration of bioceramic alumina-based granules, hydroxyapatite-based granules, and deproteinized bone granules. The experiment was conducted on 52 adult male Kyoto-Wistar rats weighing 350 to 520 g. The animals were divided into five matched groups that differed only in the type of an implanted material. The granules were implanted in the lumbar vertebral bodies and in the distal right femur of each laboratory animal. Two months after surgery, the animals were euthanized, followed by tissue sampling for morphological studies. An examination of specimens from the groups with implanted alumina granules revealed the newly formed trabecular bone with remodeling signs. The bone tissue filled the intragranular space, tightly adhering to the granule surface. There was no connective tissue capsule on the border between bone tissue and alumina granules. Cylindrical bioceramic alumina-based granules with an open internal channel have a higher strength surpassing than that of analogs and the osseointegration ability close to that of hydroxyapatite and deproteinized bone granules.

  4. Adsorptive desulfurization by activated alumina.

    PubMed

    Srivastav, Ankur; Srivastava, Vimal Chandra

    2009-10-30

    This study reports usage of commercial grade activated alumina (aluminum oxide) as adsorbent for the removal of sulfur from model oil (dibenthiophene (DBT) dissolved in n-hexane). Bulk density of alumina was found to be 1177.77 kg/m(3). The BET surface area of alumina was found to decrease from 143.6 to 66.4 m(2)/g after the loading of DBT at optimum conditions. The carbon-oxygen functional groups present on the surface of alumina were found to be effective in the adsorption of DBT onto alumina. Optimum adsorbent dose was found to be 20 g/l. The adsorption of DBT on alumina was found to be gradual process, and quasi-equilibrium reached in 24 h. Langmuir isotherm best represented the equilibrium adsorption data. The heat of adsorption and change in entropy for DBT adsorption onto alumina was found to be 19.5 kJ/mol and 139.2 kJ/mol K, respectively.

  5. Gelcasting Polycrystalline Alumina

    SciTech Connect

    Janney, M.A.; Zuk, K.J.; Wei, G.C.

    2000-01-01

    OSRAM SYLVANIA INC. is a major U.S. manufacturer of high-intensity lighting. Among its products is the Lumalux TM line of high-pressure sodium vapor arc lamps, which are used for industrial, highway, and street lighting. The key to the performance of these lamps is the polycrystalline alumina (PCA) tube that is used to contain the plasma that is formed in the electric arc. That plasma consists of ionized sodium, mercury, and xenon vapors. The key attributes of the PCA tubes are their transparency ({approximately}97% total transmittance in the visible), their refractoriness (inner wall temperature can reach l2OOC), and their chemical resistance (sodium and mercury vapor are extremely corrosive). The current efficiency of the lamps is very high, up to 100 initial lumens per watt. (Compare incandescent lamps 10-20 lumens per watt, fluorescent lamps 25-90 lumens per watt.)

  6. On the Loss of Protective Scale Formation in Creep-Resistant, Alumina-Forming Austenitic Stainless Steels at 900?aC in Air

    SciTech Connect

    Brady, Michael P; Yamamoto, Yukinori; Pint, Bruce A; Santella, Michael L; Maziasz, Philip J; Walker, Larry R

    2008-01-01

    A family of creep-resistant, Al2O3-forming austenitic (AFA) stainless steels was recently developed. The alloys exhibit excellent oxidation resistance up to 800 aC, but are susceptible to internal attack of Al at higher temperatures. In the present work, higher levels of Ni, Cr, Al, and Nb additions were found to correlate with improved oxidation behavior at 900 aC in air. The alloys generally appeared to be initially capable of external Al2O3 scale formation, with a subsequent transition to internal attack of Al (internal oxidation and internal nitridation) that is dependent on alloy composition. Compositional profiles at the alloy/scale interface suggest that the transition to internal oxidation is preceded by subsurface depletion of Al. Alloy design directions to increase the upper-temperature limit of protective Al2O3 scale formation in these alloys are discussed

  7. Patient perceptions of voice therapy adherence.

    PubMed

    van Leer, Eva; Connor, Nadine P

    2010-07-01

    Patient perspectives of behavioral voice therapy, including perspectives of treatment adherence, have not been formally documented. Because treatment adherence is, to a large extent, determined by patient beliefs, assessment of patient perspectives is integral to the study of adherence. Fifteen patients who had undergone at least two sessions of direct voice therapy for a variety of voice disorders/complaints were interviewed about their perspectives on voice therapy, with a particular focus on adherence. Interviews were transcribed and analyzed for content according to qualitative methods. Three common content themes emerged from the transcripts: Voice Therapy is Hard, Make it Happen, and The Match Matters. Findings were compared with reports of patient experiences in other behavioral interventions, such as diet and exercise, and related to existing theoretical models of behavior change and therapeutic process. This study yields information toward the development of scales to measure adherence-related constructs and strategies to improve treatment adherence in voice therapy.

  8. Global Mechanical Response and Its Relation to Deformation and Failure Modes at Various Length Scales Under Shock Impact in Alumina AD995 Armor Ceramic

    DTIC Science & Technology

    2008-03-01

    Computed Tomography: scale 0.1 mm – 1 cm: X-ray computed tomography (XCT) may be applied to any material through which a beam of penetrating... DRAWER 28510 SAN ANTONIO TX 78284 2 UNIV OF DELAWARE DEPT OF MECH ENGR J GILLESPIE NEWARK DE 19716 3 SRI INTERNATIONAL D

  9. Alumina-Reinforced Zirconia Composites

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Bansal, Narottam P.

    2003-01-01

    Alumina-reinforced zirconia composites, used as electrolyte materials for solid oxide fuel cells, were fabricated by hot pressing 10 mol percent yttria-stabilized zirconia (10-YSZ) reinforced with two different forms of alumina particulates and platelets each containing 0 to 30 mol percent alumina. Major mechanical and physical properties of both particulate and platelet composites including flexure strength, fracture toughness, slow crack growth, elastic modulus, density, Vickers microhardness, thermal conductivity, and microstructures were determined as a function of alumina content either at 25 C or at both 25 and 1000 C. Flexure strength and fracture toughness at 1000 C were maximized with 30 particulate and 30 mol percent platelet composites, respectively, while resistance to slow crack growth at 1000 C in air was greater for 30 mol percent platelet composite than for 30 mol percent particulate composites.

  10. Gelcast zirconia-alumina composites

    SciTech Connect

    Omatete, O.O.; Bleier, A.; Westmoreland, C.G.; Young, A.C.

    1991-01-01

    Near net-shaped parts of zirconia-alumina composites have been successfully formed by gelcasting, a technique which utilizes in situ polymerization of acrylamide monomers. The high solids loading required for gelcasting ({approximately}50 vol %) was obtained by controlling the pH-dependent stability of the aqueous zirconia-alumina suspensions. A strong correspondence was found among the surface charges on the particles, colloidal stability, and the maximum solids loading. 14 refs., 3 figs., 2 tabs.

  11. Enigmatic Moisture Effects on Al2O3 Scale and TBC Adhesion

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2008-01-01

    Alumina scale adhesion to high temperature alloys is known to be affected primarily by sulfur segregation and reactive element additions. However adherent scales can become partially compromised by excessive strain energy and cyclic cracking. With time, exposure of such scales to moisture can lead to spontaneous interfacial decohesion, occurring while the samples are maintained at ambient conditions. Examples of this Moisture-Induced Delayed Spallation (MIDS) are presented for NiCrAl and single crystal superalloys, becoming more severe with sulfur level and cyclic exposure conditions. Similarly, delayed failure or Desk Top Spallation (DTS) results are reviewed for TBC s, culminating in the water drop failure test. Both phenomena are discussed in terms of moisture effects on bulk alumina and bulk aluminides. A mechanism is proposed based on hydrogen embrittlement and is supported by a cathodic hydrogen charging experiment. Hydroxylation of aluminum from the alloy interface appears to be the relevant basic reaction.

  12. Enigmatic Moisture Effects on Al2O3 Scale and TBC Adhesion

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    2008-01-01

    Alumina scale adhesion to high temperature alloys is known to be affected primarily by sulfur segregation and reactive element additions. However, adherent scales can become partially compromised by excessive strain energy and cyclic cracking. With time, exposure of such scales to moisture can lead to spontaneous interfacial decohesion, occurring while the samples are maintained at ambient conditions. Examples of this Moisture-Induced Delayed Spallation (MIDS) are presented for NiCrAl and single crystal superalloys, becoming more severe with sulfur level and cyclic exposure conditions. Similarly, delayed failure or Desk Top Spallation (DTS) results are reviewed for thermal barrier coatings (TBCs), culminating in the water drop failure test. Both phenomena are discussed in terms of moisture effects on bulk alumina and bulk aluminides. A mechanism is proposed based on hydrogen embrittlement and is supported by a cathodic hydrogen charging experiment. Hydroxylation of aluminum from the alloy interface appears to be the relevant basic reaction.

  13. Influence of Alumina Reaction Tube Impurities on the Oxidation of Chemically-Vapor-Deposited Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth

    1995-01-01

    Pure coupons of chemically vapor deposited (CVD) SiC were oxidized for 100 h in dry flowing oxygen at 1300 C. The oxidation kinetics were monitored using thermogravimetry (TGA). The experiments were first performed using high-purity alumina reaction tubes. The experiments were then repeated using fused quartz reaction tubes. Differences in oxidation kinetics, scale composition, and scale morphology were observed. These differences were attributed to impurities in the alumina tubes. Investigators interested in high-temperature oxidation of silica formers should be aware that high-purity alumina can have significant effects on experiment results.

  14. Gelcasting polycrystalline alumina

    SciTech Connect

    Janney, M.A.

    1997-04-01

    This work is being done as part of a CRADA with Osram-Sylvania, Inc. (OSI) OSI is a major U.S. manufacturer of high-intensity lighting. Among its products is the Lumalux{reg_sign} line of high-pressure sodium vapor arc lamps, which are used for industrial, highway, and street lighting. The key to the performance of these lamps is the polycrystalline alumina (PCA) tube that is used to contain the plasma that is formed in the electric arc. That plasma consists of ionized sodium, mercury, and xenon vapors. The key attributes of the PCA tubes are their transparency (95% total transmittance in the visible region), their refractoriness (inner wall temperature can reach 1400{degrees}C), and their chemical resistance (sodium and mercury vapor are extremely corrosive). The current efficiency of the lamps is very high, on the order of several hundred lumens / watt. (Compare - incandescent lamps -13 lumens/watt fluorescent lamps -30 lumens/watt.) Osram-Sylvania would like to explore using gelcasting to form PCA tubes for Lumalux{reg_sign} lamps, and eventually for metal halide lamps (known as quartz-halogen lamps). Osram-Sylvania, Inc. currently manufactures PCA tubes by isostatic pressing. This process works well for the shapes that they presently use. However, there are several types of tubes that are either difficult or impossible to make by isostatic pressing. It is the desire to make these new shapes and sizes of tubes that has prompted Osram-Sylvania`s interest in gelcasting. The purpose of the CRADA is to determine the feasibility of making PCA items having sufficient optical quality that they are useful in lighting applications using gelcasting.

  15. Development of Cast Alumina-Forming Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Muralidharan, G.; Yamamoto, Y.; Brady, M. P.; Walker, L. R.; Meyer, H. M., III; Leonard, D. N.

    2016-11-01

    Cast Fe-Ni-Cr chromia-forming austenitic stainless steels with Ni levels up to 45 wt.% are used at high temperatures in a wide range of industrial applications that demand microstructural stability, corrosion resistance, and creep strength. Although alumina scales offer better corrosion protection at these temperatures, designing cast austenitic alloys that form a stable alumina scale and achieve creep strength comparable to existing cast chromia-forming alloys is challenging. This work outlines the development of cast Fe-Ni-Cr-Al austenitic stainless steels containing about 25 wt.% Ni with good creep strength and the ability to form a protective alumina scale for use at temperatures up to 800-850°C in H2O-, S-, and C-containing environments. Creep properties of the best alloy were comparable to that of HK-type cast chromia-forming alloys along with improved oxidation resistance typical of alumina-forming alloys. Challenges in the design of cast alloys and a potential path to increasing the temperature capability are discussed.

  16. Medication adherence in schizophrenia.

    PubMed

    Acosta, Francisco Javier; Hernández, José Luis; Pereira, José; Herrera, Judit; Rodríguez, Carlos J

    2012-10-22

    Non-adherence is a major problem in the treatment of schizophrenia. Its high prevalence, potentially severe consequences and associated costs make the study of this phenomenon a priority issue. In this article, basic non-adherence concepts of prevalence, consequences, evaluation methods, methodological restrictions of available studies, risk factors and intervention strategies, are reviewed. Studying non-adherence risk factors is a necessary step toward designing adequately oriented intervention strategies. An operative definition of adherence and good knowledge of its evaluation methods are essential to study this phenomenon. Unfortunately, most available studies contain methodological restrictions, especially concerning the evaluation methods, and an agreed operative definition of adherence has only very recently been reached. Knowing non-adherence risk factors, intervention strategies and available evidence on their effectiveness is essential in making treatment decisions in daily clinical practice.

  17. Precursor decay in several aluminas

    NASA Astrophysics Data System (ADS)

    Murray, N. H.; Bourne, N. K.; Rosenberg, Z.

    1996-05-01

    Plate impact experiments were performed on three ceramics with alumina content varying from 88 to 99.9% using a 50 mm single stage gas gun. Tiles of ceramic with thicknesses varying from 2 to 12 mm were impacted above their Hugoniot Elastic Limits (HELs) and the rate dependent strength was investigated by monitoring the variation in amplitude of the elastic precursor with propagation distance. Stress levels in the target were recorded using manganin stress transducers and a 1 GS s-1 storage oscilloscope. All grades of alumina were found to exhibit some elastic precursor decay indicating strain rate sensitivity.

  18. Attrition resistant gamma-alumina catalyst support

    DOEpatents

    Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

    2006-03-14

    A .gamma.-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate .gamma.-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated .gamma.-alumina.

  19. Transport properties of alumina nanofluids.

    PubMed

    Wong, Kau-Fui Vincent; Kurma, Tarun

    2008-08-27

    Recent studies have showed that nanofluids have significantly greater thermal conductivity compared to their base fluids. Large surface area to volume ratio and certain effects of Brownian motion of nanoparticles are believed to be the main factors for the significant increase in the thermal conductivity of nanofluids. In this paper all three transport properties, namely thermal conductivity, electrical conductivity and viscosity, were studied for alumina nanofluid (aluminum oxide nanoparticles in water). Experiments were performed both as a function of volumetric concentration (3-8%) and temperature (2-50 °C). Alumina nanoparticles with a mean diameter of 36 nm were dispersed in water. The effect of particle size was not studied. The transient hot wire method as described by Nagaska and Nagashima for electrically conducting fluids was used to test the thermal conductivity. In this work, an insulated platinum wire of 0.003 inch diameter was used. Initial calibration was performed using de-ionized water and the resulting data was within 2.5% of standard thermal conductivity values for water. The thermal conductivity of alumina nanofluid increased with both increase in temperature and concentration. A maximum thermal conductivity of 0.7351 W m(-1) K(-1) was recorded for an 8.47% volume concentration of alumina nanoparticles at 46.6 °C. The effective thermal conductivity at this concentration and temperature was observed to be 1.1501, which translates to an increase in thermal conductivity by 22% when compared to water at room temperature. Alumina being a good conductor of electricity, alumina nanofluid displays an increasing trend in electrical conductivity as volumetric concentration increases. A microprocessor-based conductivity/TDS meter was used to perform the electrical conductivity experiments. After carefully calibrating the conductivity meter's glass probe with platinum tip, using a standard potassium chloride solution, readings were taken at

  20. Gas chromatographic separation of hydrogen isotopes on columns packed with alumina, modified alumina and sol-gel alumina.

    PubMed

    Naik, Y P; Gupta, N K; Pillai, K T; Rao, G A Rama; Venugopal, V

    2012-01-06

    The stationary phase of alumina adsorbents, prepared by different chemical processes, was used to study the separation behaviour of hydrogen isotopes. Three types of alumina, obtained by conventional hydroxide route alumina coated with silicon oxide and alumina prepared by internal gelation process (IGP), were used as packing material to study the separation of HT and T(2) in a mixture at various temperatures. The conventional alumina and silicon oxide coated alumina resolved HT and T(2) at 77K temperature with different retention times. The retention times on SiO(2) coated columns were found to be higher than those of other adsorbents. However, the column filled with IGP alumina was found to be ideal for the separation of HT and T(2) at 240 K. The peaks were well resolved in less than 5 min on this column.

  1. Alumina-Enhanced Thermal Barrier

    NASA Technical Reports Server (NTRS)

    Smith, Marnell; Leiser, Dan; Goldstein, Howard

    1989-01-01

    Rigid, fibrous ceramic tile material called "alumina-enhanced thermal barrier" (AETB) extends temperature capability of insulating materials. Material has obvious potential for terrestrial use in kilns, furnaces, heat engines, and other applications in which light weight and high operating temperature are specified. Three kinds of ceramic fibers are blended, molded, and sintered to make refractory tiles.

  2. Impact of adherence to GOLD guidelines on 6-minute walk distance, MRC dyspnea scale score, lung function decline, quality of life, and quality-adjusted life years in a Shanghai suburb.

    PubMed

    Jiang, Y Q; Zhu, Y X; Chen, X L; Xu, X; Li, F; Fu, H J; Shen, C Y; Lu, Y Y; Zhuang, Q J; Xu, G; Cai, Y Y; Zhang, Y; Liu, S S; Zhu, M Y; Li, S H

    2015-08-03

    We performed a 1-year cluster-randomized field trial to assess the effect of standardized management of chronic obstructive pulmonary disease (COPD) on lung function and quality of life (QOL) measures in patients in China. We used the Global Initiative for Chronic Obstructive Lung Disease (GOLD) treatment guidelines and assessed indexes including pulmonary function, QOL, quality-adjusted life years (QALY), Medical Research Council (MRC) dyspnea scale, 6-min walk distance (6-MWD), number of emergency visits, and frequency of hospitalization. Of a total of 711 patients with chronic cough and asthma, 132 were diagnosed as having COPD and 102 participated in this study [intervention group (N = 47); control group (N = 55)]. We found that adherence to GOLD guidelines had a perceivable impact on 6-MWD, MRC dyspnea scale score, and QOL. The average QALY increased by 1.42/person/year in the intervention group, but declined by 0.95/person/year in the control group. We conclude that standardized management improves disease severity, QOL, and QALY in COPD patients when treatment protocols adhere to GOLD guidelines.

  3. Adherence to Antihypertensive Medications in Iranian Patients.

    PubMed

    Behnood-Rod, Azin; Rabbanifar, Omid; Pourzargar, Pirouz; Rai, Alireza; Saadat, Zahra; Saadat, Habibollah; Moharamzad, Yashar; Morisky, Donald E

    2016-01-01

    Introduction. Appropriate adherence to medication is still a challenging issue for hypertensive patients. We determined adherence to antihypertensive(s) and its associated factors among 280 Iranian patients. Methods. They were recruited consecutively from private and university health centers and pharmacies in four cities. The validated Persian version of the 8-item Morisky Medication Adherence Scale (MMAS-8) was administered to measure adherence. Results. Mean (±SD) overall MMAS-8 score was 5.75 (±1.88). About half of the sample (139 cases, 49.6%) showed low adherence (MMAS-8 score < 6). There was a negative linear association between the MMAS-8 score and systolic BP (r = -0.231, P < 0.001) as well as diastolic BP (r = -0.280, P < 0.001). In linear regression model, overweight/obesity (B = -0.52, P = 0.02), previous history of admission to emergency services due to hypertensive crisis (B = -0.79, P = 0.001), and getting medication directly from drugstore without refill prescription in hand (B = -0.51, P = 0.04) were factors recognized to have statistically significant association with the MMAS-8 score. Conclusion. Antihypertensive adherence was unsatisfactory. We suggest that health care providers pay special attention and make use of the aforementioned findings in their routine visits of hypertensive patients to recognize those who are vulnerable to poor adherence.

  4. Adherence to Antihypertensive Medications in Iranian Patients

    PubMed Central

    Behnood-Rod, Azin; Rabbanifar, Omid; Pourzargar, Pirouz; Rai, Alireza; Saadat, Zahra; Saadat, Habibollah; Moharamzad, Yashar; Morisky, Donald E.

    2016-01-01

    Introduction. Appropriate adherence to medication is still a challenging issue for hypertensive patients. We determined adherence to antihypertensive(s) and its associated factors among 280 Iranian patients. Methods. They were recruited consecutively from private and university health centers and pharmacies in four cities. The validated Persian version of the 8-item Morisky Medication Adherence Scale (MMAS-8) was administered to measure adherence. Results. Mean (±SD) overall MMAS-8 score was 5.75 (±1.88). About half of the sample (139 cases, 49.6%) showed low adherence (MMAS-8 score < 6). There was a negative linear association between the MMAS-8 score and systolic BP (r = −0.231, P < 0.001) as well as diastolic BP (r = −0.280, P < 0.001). In linear regression model, overweight/obesity (B = −0.52, P = 0.02), previous history of admission to emergency services due to hypertensive crisis (B = −0.79, P = 0.001), and getting medication directly from drugstore without refill prescription in hand (B = −0.51, P = 0.04) were factors recognized to have statistically significant association with the MMAS-8 score. Conclusion. Antihypertensive adherence was unsatisfactory. We suggest that health care providers pay special attention and make use of the aforementioned findings in their routine visits of hypertensive patients to recognize those who are vulnerable to poor adherence. PMID:27069676

  5. Wettability of Aluminum on Alumina

    NASA Astrophysics Data System (ADS)

    Bao, Sarina; Tang, Kai; Kvithyld, Anne; Tangstad, Merete; Engh, Thorvald Abel

    2011-12-01

    The wettability of molten aluminum on solid alumina substrate has been investigated by the sessile drop technique in a 10-8 bar vacuum or under argon atmosphere in the temperature range from 1273 K to 1673 K (1000 °C to 1400 °C). It is shown that the reduction of oxide skin on molten aluminum is slow under normal pressures even with ultralow oxygen potential, but it is enhanced in high vacuum. To describe the wetting behavior of the Al-Al2O3 system at lower temperatures, a semiempirical calculation was employed. The calculated contact angle at 973 K (700 °C) is approximately 97 deg, which indicates that aluminum does not wet alumina at aluminum casting temperatures. Thus, a priming height is required for aluminum to infiltrate a filter. Wetting in the Al-Al2O3 system increases with temperature.

  6. Alumina as a Thermoluminescent Material

    SciTech Connect

    Uzun, Erdem; Yarar, Yasemin

    2007-04-23

    Thermoluminescence dosimeters are extensively used for quantitative dose measurements in various irradiation fields. They are also important for environmental monitoring after nuclear accident and weapon tests. In this work, the principles of TLD dosimeter and characteristics of several TLD materials are presented. Besides, taken into account the importance as a raw material, the utilization of domestic alumina (Al2O3) in TLDs as a thermoluminescent material is discussed.

  7. Bacteria repelling on highly-ordered alumina-nanopore structures

    NASA Astrophysics Data System (ADS)

    Kim, Sunghan; Zhou, Yan; Cirillo, Jeffrey D.; Polycarpou, Andreas A.; Liang, Hong

    2015-04-01

    Bacteria introduce diseases and infections to humans by their adherence to biomaterials, such as implants and surgical tools. Cell desorption is an effective step to reduce such damage. Here, we report mechanisms of bacteria desorption. An alumina nanopore structure (ANS) with pore size of 35 nm, 55 nm, 70 nm, and 80 nm was used as substrate to grow Escherichia coli (E. coli) cells. A bacteria repelling experimental method was developed to quantitatively evaluate the area percentage of adherent bacterial cells that represent the nature of cell adhesion as well as desorption. Results showed that there were two crucial parameters: contact angle and contact area that affect the adhesion/desorption. The cells were found to be more easily repelled when the contact angle increased. The area percentage of adherent bacterial cells decreased with the decrease in the contact area of a cell on ANS. This means that cell accessibility on ANS depends on the contact area. This research reveals the effectiveness of the nanopored structures in repelling cells.

  8. Hypervelocity impact damage in alumina

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng

    2007-12-01

    Ceramics are important engineering materials for their outstanding hardness. One of the most widely used ceramics is alumina, a candidate for armor in defense and aerospace industry. Deformation and fracture mechanisms in alpha-alumina under hypervelocity impact up to 18km/s are investigated using molecular dynamics (MD) simulations containing 540-million atoms. Impacting projectile causes melting and local amorphization of the substrate in a spherical surrounding region. Away from the impact face, a wide range of deformations emerge and disappear under the influence of local stress fields, e.g., basal and pyramidal slips, basal and rhombohedral twins, which show good agreement with the experimental and theoretical results. Furthermore, new deformation modes such as twin along {01¯11} are observed, and the relation between deformation patterns and local stress levels are probed. During unloading, micro-cracks nucleate extensively at the intersections of previous deformations. These micro-cracks grow and coalesce to form fractures under tensile stresses by the unloading wave. The substrate eventually fails along the surface of an hourglass-shaped region, when spallation ejects clusters of substrate material into the vacuum. We also carried out planar shock simulations of alpha-alumina single crystal and nanophase systems. The results show correlations between the atomistic deformation mechanisms and the elastic-plastic response of ceramic material observed in shock loading experiments.

  9. Method for preparing Pb-. beta. ''-alumina ceramic

    DOEpatents

    Hellstrom, E.E.

    1984-08-30

    A process is disclosed for preparing impermeable, polycrystalline samples of Pb-..beta..''-alumina ceramic from Na-..beta..''-alumina ceramic by ion exchange. The process comprises two steps. The first step is a high-temperature vapor phase exchange of Na by K, followed by substitution of Pb for K by immersing the sample in a molten Pb salt bath. The result is a polycrystalline Pb-..beta..''-alumina ceramic that is substantially crack-free.

  10. Structural Effects of Lanthanide Dopants on Alumina

    NASA Astrophysics Data System (ADS)

    Patel, Ketan; Blair, Victoria; Douglas, Justin; Dai, Qilin; Liu, Yaohua; Ren, Shenqiang; Brennan, Raymond

    2017-01-01

    Lanthanide (Ln3+) doping in alumina has shown great promise for stabilizing and promoting desirable phase formation to achieve optimized physical and chemical properties. However, doping alumina with Ln elements is generally accompanied by formation of new phases (i.e. LnAlO3, Ln2O3), and therefore inclusion of Ln-doping mechanisms for phase stabilization of the alumina lattice is indispensable. In this study, Ln-doping (400 ppm) of the alumina lattice crucially delays the onset of phase transformation and enables phase population control, which is achieved without the formation of new phases. The delay in phase transition (θ → α), and alteration of powder morphology, particle dimensions, and composition ratios between α- and θ-alumina phases are studied using a combination of solid state nuclear magnetic resonance, electron microscopy, digital scanning calorimetry, and high resolution X-ray diffraction with refinement fitting. Loading alumina with a sparse concentration of Ln-dopants suggests that the dopants reside in the vacant octahedral locations within the alumina lattice, where complete conversion into the thermodynamically stable α-domain is shown in dysprosium (Dy)- and lutetium (Lu)-doped alumina. This study opens up the potential to control the structure and phase composition of Ln-doped alumina for emerging applications.

  11. Physical chemistry of carbothermic reduction of alumina

    SciTech Connect

    Frank, Robert A.

    1985-09-01

    Production of aluminium, by means of carbothermic reduction of alumina, is discussed. By employing a solvent metal bath to absorb the alumina metal, carbothermic reduction of alumina was accomplished at temperatures 300/degree/C lower than the temperatures reported in the literature. Reduction occurred without the formation of intermediate compounds and without the high volatilization of aluminum bearing species. Reduction of alumina immersed in a solvent bath appeared to be rate limited by chemical reaction control. The rates seemed to be a function of the activity of aluminum in the solvent metal bath. Reduction of alumina particles, above the surface of the bath, seemed to occur via vapor transport with carbon in the particles or in the crucible walls. Mass transport in the gas phase appeared to be rate limiting. The rates seemed to be a function of the distance separating the alumina and carbon sources. With both submerged alumina and alumina particles, increasing the surface area of the alumina increased the rate of reduction. 58 refs., 65 figs., 9 tabs.

  12. Structural Effects of Lanthanide Dopants on Alumina

    DOE PAGES

    Patel, Ketan; Blair, Victoria; Douglas, Justin; ...

    2017-01-06

    Lanthanide (Ln3+) doping in alumina has shown great promise for stabilizing and promoting desirable phase formation to achieve optimized physical and chemical properties. However, doping alumina with Ln elements is generally accompanied by formation of new phases (i.e. LnAlO3, Ln2O3), and therefore inclusion of Ln-doping mechanisms for phase stabilization of the alumina lattice is indispensable. In this study, Ln-doping (400 ppm) of the alumina lattice crucially delays the onset of phase transformation and enables phase population control, which is achieved without the formation of new phases. In addition, the delay in phase transition (θ → α), and alteration of powdermore » morphology, particle dimensions, and composition ratios between α- and θ-alumina phases are studied using a combination of solid state nuclear magnetic resonance, electron microscopy, digital scanning calorimetry, and high resolution X-ray diffraction with refinement fitting. Loading alumina with a sparse concentration of Ln-dopants suggests that the dopants reside in the vacant octahedral locations within the alumina lattice, where complete conversion into the thermodynamically stable α-domain is shown in dysprosium (Dy)- and lutetium (Lu)-doped alumina. Lastly, this study opens up the potential to control the structure and phase composition of Ln-doped alumina for emerging applications.« less

  13. Structural Effects of Lanthanide Dopants on Alumina

    PubMed Central

    Patel, Ketan; Blair, Victoria; Douglas, Justin; Dai, Qilin; Liu, Yaohua; Ren, Shenqiang; Brennan, Raymond

    2017-01-01

    Lanthanide (Ln3+) doping in alumina has shown great promise for stabilizing and promoting desirable phase formation to achieve optimized physical and chemical properties. However, doping alumina with Ln elements is generally accompanied by formation of new phases (i.e. LnAlO3, Ln2O3), and therefore inclusion of Ln-doping mechanisms for phase stabilization of the alumina lattice is indispensable. In this study, Ln-doping (400 ppm) of the alumina lattice crucially delays the onset of phase transformation and enables phase population control, which is achieved without the formation of new phases. The delay in phase transition (θ → α), and alteration of powder morphology, particle dimensions, and composition ratios between α- and θ-alumina phases are studied using a combination of solid state nuclear magnetic resonance, electron microscopy, digital scanning calorimetry, and high resolution X-ray diffraction with refinement fitting. Loading alumina with a sparse concentration of Ln-dopants suggests that the dopants reside in the vacant octahedral locations within the alumina lattice, where complete conversion into the thermodynamically stable α-domain is shown in dysprosium (Dy)- and lutetium (Lu)-doped alumina. This study opens up the potential to control the structure and phase composition of Ln-doped alumina for emerging applications. PMID:28059121

  14. Characterisation of dynamic behaviour of alumina ceramics: evaluation of stress uniformity

    NASA Astrophysics Data System (ADS)

    Wang, Zhiyong; Li, Peifeng

    2015-10-01

    Accurate characterisation of dynamic behaviour of ceramics requires the reliable split-Hopkinson pressure bar (SHPB) technique and the condition of uniaxial homogeneous specimen deformation. In this study, an experimentally validated 3D finite element model of the full scale SHPB experiment was developed to quantitatively evaluate the wave propagation in the bars and the stress distribution/evolution in the alumina specimen. Wave signals in both the SHPB experiments and the finite element model were analysed to characterise the dynamic behaviour of alumina. It was found that the equilibrium of both stresses within the specimen and forces at the specimen ends can be established in the intermediate stage of deformation. The validity of stress uniformity in the alumina specimen supports the assumption of uniaxial homogeneous specimen deformation in the SHPB and validates the characterisation of dynamic behaviour of alumina ceramics.

  15. Stability of trapped charges in sapphires and alumina ceramics: Evaluation by secondary electron emission

    NASA Astrophysics Data System (ADS)

    Zarbout, K.; Si Ahmed, A.; Moya, G.; Bernardini, J.; Goeuriot, D.; Kallel, A.

    2008-03-01

    The stability of trapped charges in sapphires and alumina ceramics is characterized via an experimental parameter expressing the variation of the secondary electron emission yield between two electron injections performed in a scanning electron microscope. Two types of sapphires and polycrystalline alumina, which differ mainly by their impurity content, are investigated in the temperature range 300-663K. The stable trapping behavior in sapphires is attributed to trapping in different defects, whose nature depends on the purity level. In alumina ceramics, the ability to trap charges in a stable way is stronger in samples of high impurity content. In the low impurity samples, stable trapping is promoted when the grain diameter decreases, whereas the reverse is observed in high impurity materials. These behaviors can stem from a gettering effect occurring during sintering. The strong dependence of the variation of the secondary electron emission yield on the grain diameter and impurities enables a scaling of the stable trapping ability of alumina materials.

  16. Microbicide clinical trial adherence: insights for introduction

    PubMed Central

    Woodsong, Cynthia; MacQueen, Kathleen; Amico, K Rivet; Friedland, Barbara; Gafos, Mitzy; Mansoor, Leila; Tolley, Elizabeth; McCormack, Sheena

    2013-01-01

    After two decades of microbicide clinical trials it remains uncertain if vaginally- delivered products will be clearly shown to reduce the risk of HIV infection in women and girls. Furthermore, a microbicide product with demonstrated clinical efficacy must be used correctly and consistently if it is to prevent infection. Information on adherence that can be gleaned from microbicide trials is relevant for future microbicide safety and efficacy trials, pre-licensure implementation trials, Phase IV post-marketing research, and microbicide introduction and delivery. Drawing primarily from data and experience that has emerged from the large-scale microbicide efficacy trials completed to-date, the paper identifies six broad areas of adherence lessons learned: (1) Adherence measurement in clinical trials, (2) Comprehension of use instructions/Instructions for use, (3) Unknown efficacy and its effect on adherence/Messages regarding effectiveness, (4) Partner influence on use, (5) Retention and continuation and (6) Generalizability of trial participants' adherence behavior. Each is discussed, with examples provided from microbicide trials. For each of these adherence topics, recommendations are provided for using trial findings to prepare for future microbicide safety and efficacy trials, Phase IV post-marketing research, and microbicide introduction and delivery programs. PMID:23561044

  17. Perfluoropolyalkylether decomposition on catalytic aluminas

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo

    1994-01-01

    The decomposition of Fomblin Z25, a commercial perfluoropolyalkylether liquid lubricant, was studied using the Penn State Micro-oxidation Test, and a thermal gravimetric/differential scanning calorimetry unit. The micro-oxidation test was conducted using 440C stainless steel and pure iron metal catalyst specimens, whereas the thermal gravimetric/differential scanning calorimetry tests were conducted using catalytic alumina pellets. Analysis of the thermal data, high pressure liquid chromatography data, and x-ray photoelectron spectroscopy data support evidence that there are two different decomposition mechanisms for Fomblin Z25, and that reductive sites on the catalytic surfaces are responsible for the decomposition of Fomblin Z25.

  18. Development of Alumina-Forming Austenitic Stainless Steels

    SciTech Connect

    Brady, Michael P; Yamamoto, Yukinori; Bei, Hongbin; Santella, Michael L; Maziasz, Philip J

    2009-01-01

    This paper presents the results of the continued development of creep-resistant, alumina-forming austenitic (AFA) stainless steel alloys, which exhibit a unique combination of excellent oxidation resistance via protective alumina (Al2O3) scale formation and high-temperature creep strength through the formation of stable nano-scale MC carbides and intermetallic precipitates. Efforts in fiscal year 2009 focused on the characterization and understanding of long-term oxidation resistance and tensile properties as a function of alloy composition and microstructure. Computational thermodynamic calculations of the austenitic matrix phase composition and the volume fraction of MC, B2-NiAl, and Fe2(Mo,Nb) base Laves phase precipitates were used to interpret oxidation behavior. Of particular interest was the enrichment of Cr in the austenitic matrix phase by additions of Nb, which aided the establishment and maintenance of alumina. Higher levels of Nb additions also increased the volume fraction of B2-NiAl precipitates, which served as an Al reservoir during long-term oxidation. Ageing studies of AFA alloys were conducted at 750 C for times up to 2000 h. Ageing resulted in near doubling of yield strength at room temperature after only 50 h at 750 C, with little further increase in yield strength out to 2000 h of ageing. Elongation was reduced on ageing; however, levels of 15-25% were retained at room temperature after 2000 h of total ageing.

  19. Formation of alumina-nickel-molybdenum catalysts

    SciTech Connect

    Erofeev, V.I.; Basov, V.G.; Vagin, A.I.; Kalechits, I.V.

    1982-06-01

    On the basis of the results obtained in physical and chemical studies of alumina-nickel-molybdenum oxide catalysts as well as binary system and the individual oxides, the conclusions show that the commercial catalyst consists mainly of nickel and aluminium molybdates, aluminium molybdates, molybdenum oxide, and the alumina support. 4 figures.

  20. Hydrogen and the structure of transition aluminas

    SciTech Connect

    Sohlberg, K.; Pennycook, S.J.; Pantelides, S.T.

    1999-08-25

    {alpha}-Alumina results from the complete dehydration of several minerals of the form Al{sub 2}O{sub 3}{center{underscore}dot}nH{sub 2}O. The ``transition'' aluminas, {gamma}-alumina, {eta}-alumina, and {delta}-alumina are known to have a spinel structure but the possibility that they contain hydrogen (H) has been the subject of debate. The authors present a series of density-functional theory calculations which, together with available experimental data, show that the spinel aluminas exist over a range of hydrogen content captured by the empirical formula H{sub 3m}Al{sub 2{minus}m}O{sub 3}, with a different greek-letter phases corresponding to different distributions of the Aluminum (Al) ions on the two cation sublattices. Calculations of densities and vibrational frequencies of bulk OH bonds are in excellent agreement with available data. The theory reconciles seemingly inconsistent data and reveals a remarkable property of the spinel aluminas: They are ``reactive sponges'' in that they can store and release water in a reactive way. This chemical activity offers a basis for understanding long-standing puzzles in the behavior of aluminas in catalytic systems.

  1. Effects of Impurities on Alumina-Niobium InterfacialMicrostructures

    SciTech Connect

    McKeown, Joseph T.; Sugar, Joshua D.; Gronsky, Ronald; Glaeser,Andreas M.

    2005-06-20

    Optical microscopy, scanning electron microscopy, and transmission electron microscopy were employed to examine the interfacial microstructural effects of impurities in alumina substrates used to fabricate alumina-niobium interfaces via liquid-film-assisted joining. Three types of alumina were used: undoped high-purity single-crystal sapphire; a high-purity, high-strength polycrystalline alumina; and a lower-purity, lower-strength polycrystalline alumina. Interfaces formed between niobium and both the sapphire and high-purity polycrystalline alumina were free of detectable levels of impurities. In the lower-purity alumina, niobium silicides were observed at the alumina-niobium interface and on alumina grain boundaries near the interface. These silicides formed in small-grained regions of the alumina and were found to grow from the interface into the alumina along grain boundaries. Smaller silicide precipitates found on grain boundaries are believed to form upon cooling from the bonding temperature.

  2. ARSENIC REMOVAL FROM DRINKING WATER BY ACTIVATED ALUMINA AND ANION EXCHANGE TREATMENT

    EPA Science Inventory

    This paper discusses the results of a one year performance evaluation study of two full scale ion exchange plants and two full scale activated alumina plant that were designed and operated for the removal of arsenic from well water. All the plants were shown to be capable of red...

  3. Adherence to Antihypertensives in Patients With Comorbid Condition

    PubMed Central

    Saadat, Zahra; Nikdoust, Farahnaz; Aerab-Sheibani, Hossein; Bahremand, Mostafa; Shobeiri, Elham; Saadat, Habibollah; Moharramzad, Yashar; Morisky, Donald E.

    2015-01-01

    Background: Comorbidity has been noted as a potential barrier to proper adherence to antihypertensive medications. Objectives: We decided to investigate whether comorbidity could significantly affect adherence of Iranian patients with hypertension to their medication regimen. Patients and Methods: Two hundred and eighty consecutive hypertensive patients were interviewed in 4 cities of Iran. The 8-item Morisky medication adherence scale (MMAS-8) (validated in Persian) was used to assess medication adherence. This scale determines adherence by scores as lower than 6 (low adherence), 6 or 7 (moderate adherence), and 8 (high adherence). Comorbidity was considered as any concomitant medical condition, which necessitates the patient to take medicine for a minimum of 6 months prior to the interviews. Results: The most common comorbid conditions were ischemic heart disease (65 patients, 23.2%), diabetes mellitus (55 patients, 19.6%), and dyslipidemia (51 patients, 18.2%). Mean (± SD) MMAS-8 score in comorbid group was 5.68 (± 1.85) and in non-comorbid hypertensive patients, it was 5.83 (± 1.91) (P = 0.631). Mean (± SD) number of comorbidities was 1.53 (± 0.75) in low adherence group compared to 1.54 (± 0.77) in moderate/high adherers (P = 0.98). With increasing the number of comorbid diseases, the proportion of patients with high adherence decreased successively from 20% in those with no comorbid disease to 14.1% in those with one or two comorbid conditions, and finally 11.1% in those with 3 to 5 comorbid conditions. Conclusions: With increasing the number of comorbid conditions, the proportion of patients with high adherence decreases. In our opinion, this finding is a useful clinical note for healthcare providers when managing patients with hypertension who have other medical problems at the same time. PMID:26539419

  4. Fabrication of dense α-alumina layer on Ti-6Al-4V alloy hybrid for bearing surfaces of artificial hip joint.

    PubMed

    Khanna, Rohit; Kokubo, Tadashi; Matsushita, Tomiharu; Takadama, Hiroaki

    2016-12-01

    Recent advances in hip replacements are focused towards producing reliable bearing surfaces to enhance their longevity. In this perspective, progressive attempts have been made to improve the wear resistance of polyethylene to eliminate osteolysis and mechanical reliability of brittle alumina ceramics, but in vain. It is proposed that both high wear resistance and mechanical reliability can be retained if a thin layer of dense alumina is formed onto high toughness Ti-6Al-4V alloy. For this purpose, we devised a unique methodology in which a layer of Al metal was deposited onto the Ti alloy substrate by cold spraying (CS), followed by a heat treatment to form Al3Ti reaction layer at their interface to improve adhesion and subsequent micro-arc oxidation (MAO) treatment to transform Al to alumina layer. An optimal MAO treatment of cold sprayed Al formed an adherent and dense α-alumina layer with high Vickers hardness matching with that of sintered alumina used as a femoral head. Structure-phase-property relationships in dense α-alumina layer have been revealed and discussed in the light of our research findings. The designed alumina/Ti alloy hybrid might be a potential candidate for reliable bearing surfaces of artificial hip joint.

  5. Characterization and application of electrospun alumina nanofibers

    PubMed Central

    2014-01-01

    Alumina nanofibers were prepared by a technique that combined the sol–gel and electrospinning methods. The solution to be electrospun was prepared by mixing aluminum isopropoxide (AIP) in ethanol, which was then refluxed in the presence of an acid catalyst and polyvinylpyrolidone (PVP) in ethanol. The characterization results showed that alumina nanofibers with diameters in the range of 102 to 378 nm were successfully prepared. On the basis of the results of the XRD and FT-IR, the alumina nanofibers calcined at 1,100°C were identified as comprising the α-alumina phase, and a series of phase transitions such as boehmite → γ-alumina → α-alumina were observed from 500°C to 1,200°C. The pore size of the obtained γ-alumina nanofibers is approximately 8 nm, and it means that they are mesoporous materials. The kinetic study demonstrated that MO adsorption on alumina nanofibers can be seen that the pseudo-second-order kinetic model fits better than the pseudo-first-order kinetic model. PMID:24467944

  6. Size-controlled Synthesis and Evaluation of Optical Properties of Alumina Nanoparticles

    NASA Astrophysics Data System (ADS)

    Gangwar, J.; Srivastava, A. K.; Tripathi, S. K.

    2011-12-01

    We report the synthesis of nano-scaled alumina of varied dimensions through an optimized processing of aluminum nitrate. The X-ray diffractometry confirmed the formation of α-phase of alumina particles in the nano region, depending on the annealing conditions during processing. Subsequently, a detailed electron microscopy revealed the morphological alterations and crystallographic information even at lattice scale. The band energies were investigated by employing photoluminescence spectrometry. The evolution of fascinating microstructure, phase formations and optical bands has been presented and discussed.

  7. Noise in Sodium Beta Alumina Crystals.

    DTIC Science & Technology

    1985-09-01

    Washington, D.C. 20375 .I- 7. 7- NOISE INI SODIUM r ALUMINA SINGLE CRYSTALS James J. Brophy and Steven W. Smith University of Utah Salt Lake City, Utah 84112...RD-Ai56 025 NOISE IN SODiUN BETA ALUMINA CRYSTALS(U) UTAH UNIV SALT II LAKE CITY DEPT OF PHYSICS J J BROPHY ET AL. SEP 85 TR-7 N88814-82-K-e603...h.0- "bf’ ; -28242 ’ITLE (andSubsist&) S. TYPE OF REPORT & PERIOD COVERED L Noise in Sodium B" Alumina Crystals Technical Report #7 CJ S. PERFORMING

  8. Fabrication of thin layer beta alumina

    NASA Technical Reports Server (NTRS)

    Tennenhouse, G. J.

    1977-01-01

    Beta alumina tubes having walls 700 microns, 300 microns, and 140 microns were processed by extrusion and sintering utilizing Ford proprietary binder and fabrication systems. Tubes prepared by this method have properties similar to tubes prepared by isostatic pressing and sintering, i.e. density greater than 98% of theoretical and a helium leak rate less than 3 x 10 to the -9th power cc/sq cm/sec. Ford ultrasonic bonding techniques were used for bonding beta alumina end caps to open ended beta -alumina tubes prior to sintering. After sintering, the bond was hermetic, and the integrity of the bonded area was comparable to the body of the tube.

  9. Dissolution Kinetics of Alumina Calcine

    SciTech Connect

    Batcheller, Thomas Aquinas

    2001-09-01

    Dissolution kinetics of alumina type non-radioactive calcine was investigated as part of ongoing research that addresses permanent disposal of Idaho High Level Waste (HLW). Calcine waste was produced from the processing of nuclear fuel at the Idaho Nuclear Technology and Engineering Center (INTEC). Acidic radioactive raffinates were solidified at ~500°C in a fluidized bed reactor to form the dry granular calcine material. Several Waste Management alternatives for the calcine are presented in the Idaho High Level Waste Draft EIS. The Separations Alternative addresses the processing of the calcine so that the HLW is ready for removal to a national geological repository by the year 2035. Calcine dissolution is the key front-end unit operation for the separations alternative.

  10. Ethical considerations in adherence research

    PubMed Central

    Patel, Nupur U; Moore, Blake A; Craver, Rebekah F; Feldman, Steven R

    2016-01-01

    Poor adherence to treatment is a common cause of medical treatment failure. Studying adherence is complicated by the potential for the study environment to impact adherence behavior. Studies performed without informing patients about adherence monitoring must balance the risks of deception against the potential benefits of the knowledge to be gained. Ethically monitoring a patient’s adherence to a treatment plan without full disclosure of the monitoring plan requires protecting the patient’s rights and upholding the fiduciary obligations of the investigator. Adherence monitoring can utilize different levels of deception varying from stealth monitoring, debriefing after the study while informing the subject that some information had been withheld in regard to the use of adherence monitoring (withholding), informed consent that discloses some form of adherence monitoring is being used and will be disclosed at the end of the study (authorized deception), and full disclosure. Different approaches offer different benefits and potential pitfalls. The approach used must balance the risk of nondisclosure against the potential for confounding the adherence monitoring data and the potential benefits that adherence monitoring data will have for the research subjects and/or other populations. This commentary aims to define various methods of adherence monitoring and to provide a discussion of the ethical considerations that accompany the use of each method and adherence monitoring in general as it is used in clinical research. PMID:27980394

  11. Ethical considerations in adherence research.

    PubMed

    Patel, Nupur U; Moore, Blake A; Craver, Rebekah F; Feldman, Steven R

    2016-01-01

    Poor adherence to treatment is a common cause of medical treatment failure. Studying adherence is complicated by the potential for the study environment to impact adherence behavior. Studies performed without informing patients about adherence monitoring must balance the risks of deception against the potential benefits of the knowledge to be gained. Ethically monitoring a patient's adherence to a treatment plan without full disclosure of the monitoring plan requires protecting the patient's rights and upholding the fiduciary obligations of the investigator. Adherence monitoring can utilize different levels of deception varying from stealth monitoring, debriefing after the study while informing the subject that some information had been withheld in regard to the use of adherence monitoring (withholding), informed consent that discloses some form of adherence monitoring is being used and will be disclosed at the end of the study (authorized deception), and full disclosure. Different approaches offer different benefits and potential pitfalls. The approach used must balance the risk of nondisclosure against the potential for confounding the adherence monitoring data and the potential benefits that adherence monitoring data will have for the research subjects and/or other populations. This commentary aims to define various methods of adherence monitoring and to provide a discussion of the ethical considerations that accompany the use of each method and adherence monitoring in general as it is used in clinical research.

  12. Factors influencing adherence among older people with osteoarthritis.

    PubMed

    Loew, Laurianne; Brosseau, Lucie; Kenny, Glen P; Durand-Bush, Natalie; Poitras, Stéphane; De Angelis, Gino; Wells, George A

    2016-09-01

    This study aims to identify potential factors that could affect adherence and influence the implementation of an evidence-based structured walking program, among older adults diagnosed with knee osteoarthritis. A total of 69 participants with mild to moderate osteoarthritis of the knee fulfilled an online survey on potential factors that could affect their adherence to an evidence-based structured walking program. Adherence with regard to the influencing factors was explored using a logistic regression model. Results tend to show higher odds of adhering to the evidence-based walking program if the participants were supervised (more than 2.9 times as high), supported by family/friends (more than 3.7 times as high), and not influenced by emotional involvement (more than 11 times as high). The odds of adhering were 3.6 times lower for participants who indicated a change in their medication intake and 3.1 times lower for individuals who considered themselves as less physically active (95 % confidence interval (CI)). Our exploratory findings identified and defined potential adherence factors that could guide health professionals in their practice to better identify positive influences and obstacles to treatment adherence, which would lead to the adoption of a more patient-centered approach. A large-scale study is required to clearly delineate the key factors that would influence adherence. We addressed a new knowledge gap by identifying the main strategies to promote the long-term adherence of community-based walking program.

  13. Cast alumina forming austenitic stainless steels

    DOEpatents

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P

    2013-04-30

    An austenitic stainless steel alloy consisting essentially of, in terms of weight percent ranges 0.15-0.5C; 8-37Ni; 10-25Cr; 2.5-5Al; greater than 0.6, up to 2.5 total of at least one element selected from the group consisting of Nb and Ta; up to 3Mo; up to 3Co; up to 1W; up to 3Cu; up to 15Mn; up to 2Si; up to 0.15B; up to 0.05P; up to 1 total of at least one element selected from the group consisting of Y, La, Ce, Hf, and Zr; <0.3Ti+V; <0.03N; and, balance Fe, where the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale comprising alumina, and a stable essentially single phase FCC austenitic matrix microstructure, the austenitic matrix being essentially delta-ferrite free and essentially BCC-phase-free. A method of making austenitic stainless steel alloys is also disclosed.

  14. Medication adherence: process for implementation

    PubMed Central

    Mendys, Phil; Zullig, Leah L; Burkholder, Rebecca; Granger, Bradi B; Bosworth, Hayden B

    2014-01-01

    Improving medication adherence is a critically important, but often enigmatic objective of patients, providers, and the overall health care system. Increasing medication adherence has the potential to reduce health care costs while improving care quality, patient satisfaction and health outcomes. While there are a number of papers that describe the benefits of medication adherence in terms of cost, safety, outcomes, or quality of life, there are limited reviews that consider how best to seamlessly integrate tools and processes directed at improving medication adherence. We will address processes for implementing medication adherence interventions with the goal of better informing providers and health care systems regarding the safe and effective use of medications. PMID:25114513

  15. Joining of alumina ceramics and nickel alloy

    SciTech Connect

    Ariga, Tadashi; Nitta, Yuji; Miyazawa, Yasuyuki

    1994-12-31

    Joining of alumina ceramics to nickel alloy was made using the various types of Ag-Cu-Ti brazing filler metal. Ti-containing brazing filler metal was produced by physical vapor deposition (PVD) method on the joining area of the alumina ceramics. The joinability of the brazing filler metal was estimated by its mechanical properties. And the composition and structure of the ceramic-metal bond zone in the alumina ceramics-nickel alloy joints were analyzed by SEM, EPMA and X-ray diffraction examinations. Some of brazing filler metal achieved the highest shear strength 100 MPa at room temperature. The elemental distributions of the interface between alumina ceramics and Ag-Cu-Ti brazing filler metal was shown to form the reaction layer consisting titanium oxide.

  16. Electrical Properties of Thin Films of Alumina.

    DTIC Science & Technology

    The report consists of a literature survey on the electrical properties of alumina and aluminum oxide thin films . A bibliographic listing of reports is included along with abstracts from most of them.

  17. Loss tangent measurements on unirradiated alumina

    SciTech Connect

    Zinkle, S.J.; Goulding, R.H.

    1996-04-01

    Unirradiated room temperature loss tangent for sapphire and several commercial grades of polycrystalline alumina are complied for frequencies between 10{sup 5} and 4x10{sup 11} Hz. Sapphire exhibits significantly lower values for the loss tangent at frequencies up to 10{sup 11} Hz. The loss tangents of 3 different grades of Wesgo alumina (AL300, AL995, AL998) and 2 different grades of Coors alumina (AD94, AD995) have typical values near {approx}10{sup -4} at a frequency of 10{sup 8} Hz. On the other hand, the loss tangent of Vitox alumina exhibits a large loss peak tan d{approx} 5x10{sup -3} at this frequency.

  18. Processing of Alumina-Toughened Zirconia Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Choi, Sung R.

    2003-01-01

    Dense and crack-free 10-mol%-yttria-stabilized zirconia (10YSZ)-alumina composites, containing 0 to 30 mol% of alumina, have been fabricated by hot pressing. Release of pressure before onset of cooling was crucial in obtaining crack-free material. Hot pressing at 1600 C resulted in the formation of ZrC by reaction of zirconia with grafoil. However, no such reaction was observed at 1500 C. Cubic zirconia and -alumina were the only phases detected from x-ray diffraction indicating no chemical reaction between the composite constituents during hot pressing. Microstructure of the composites was analyzed by scanning electron microscopy and transmission electron microscopy. Density and elastic modulus of the composites followed the rule-of-mixtures. Addition of alumina to 10YSZ resulted in lighter, stronger, and stiffer composites by decreasing density and increasing strength and elastic modulus.

  19. Preparation and Characterization of Electrospun Alumina Nanofibers

    NASA Astrophysics Data System (ADS)

    Pinti, Marie J.; Tacastacas, Stephen N.; Stojilovic, Nenad; O'Brien, John P.; Pischera, Anna; Espe, Matthew P.

    2008-10-01

    Alumina nanofibers are promising materials for use in high- temperature applications since they are chemically inert up to very high temperatures. Applications include use as catalyst support in high-temperature chemical reactions, fire protection materials, and as a high-temperature insulator. Electrospinning is a relatively simple and inexpensive method for obtaining nanometer-size fibers and has become a popular technique for producing metal-oxide nanofibers in recent years. The electrospinning mixture for the production of alumina nanofibers typically contains aluminum acetate stabilized with boric acid as the alumina precursor; but the observed presence of boron and sodium on the surface of these nanofibers may affect their use as catalytic supports. We have produced alumina nanofibers from an aluminum reagent devoid of the boric acid stabilizer and calcined the fibers at different temperatures to produce nanofibers with different phases of alumina. Characterization of the fibers by TGA, FE-SEM equipped with the XEDS, powder XRD, DRIFTS, and SSNMR methods to determine the fate of the precursors, fiber morphology and the composition and structure of the calcined alumina nanofibers.

  20. Oxidation of Alumina-Forming MAX Phases in Turbine Environments

    NASA Technical Reports Server (NTRS)

    Smialek, James; Garg, Anita; Harder, Bryan; Nesbitt, James; Gabb, Timothy; Gray, SImon

    2017-01-01

    Protective coatings for high temperature turbine components are based on YSZ thermal barriers and oxidation resistant, alumina-forming NiAl or NiCoCrAlY bond coats. Ti2AlC and Cr2AlC MAX phases are thus of special interest because of good oxidation resistance and CTE that can match Al2O3 and YSZ. Their alumina scales grow according to cubic kinetics due to grain growth in the scale, with initial heating dominated by fast TiO2 growth. Protective cubic kinetics are also found in high pressure burner rig tests of MAXthal 211 Ti2AlC, but with reduced rates due to volatile TiO(OH)2 formation in water vapor. YSZ-coatings on bulk Ti2AlC exhibit remarkable durability up to 1300C in furnace tests and at least a 25x life advantage compared to superalloys. At another extreme, Cr2AlC is resistant to low temperature Na2SO4 hot corrosion and exhibits thermal cycling stability bonded to a superalloy disk material. Accordingly, sputtered Cr2AlC coatings on disk specimens prevented hot corrosion detriments on LCF. Breakaway oxidation (Ti2AlC), scale spallation (Cr2AlC), interdiffusion, and processing as coatings still present serious challenges. However the basic properties of MAX phases provide some unusual opportunities for use in high temperature turbines.

  1. Development of Alumina-Forming Austenitic Stainless Steels

    SciTech Connect

    Yamamoto, Yukinori; Brady, Michael P; Santella, Michael L; Bei, Hongbin; Maziasz, Philip J; Pint, Bruce A

    2008-01-01

    Work in fiscal year 2008 focused on the development of creep-resistant, alumina-forming austenitic (AFA) stainless steel alloys, which exhibit a unique combination of an excellent oxidation resistance via protective alumina (Al2O3) scale formation and high-temperature creep strength through the formation of stable nano-scale MC carbides [1-8]. High levels of Nb additions (> 1 wt.% Nb) and/or Ni additions (25-30 wt.%), at Al levels of 2.5-4 wt.%, were found to correlate with increased upper-temperature limit for Al2O3 scale formation in air ( 900 aC) and air with 10% water vapor ( 800 aC). Creep resistance also showed a strong dependence on the level of Nb additions, and was correlated with volume fraction of MC-type carbides using thermodynamic computational tools. A trial heat of a 50 lb AFA alloy ingot was made using conventional single-melt vacuum techniques, and the alloy was successfully hot-rolled without any cracking [2]. This heat showed good weldability, using filler material of the same alloy.

  2. Correlates of Pediatric CPAP Adherence

    PubMed Central

    Hawkins, Stephen M.M.; Jensen, Emily L.; Simon, Stacey L.; Friedman, Norman R.

    2016-01-01

    Study Objectives: Obstructive sleep apnea (OSA) is a common pediatric condition characterized by recurrent partial or complete cessation of airflow during sleep, typically due to inadequate upper airway patency. Continuous positive airway pressure (CPAP) is a therapeutic option that reduces morbidity. Despite efforts to promote use, CPAP adherence is poor in both pediatric and adult populations. We sought to determine whether demographics, insurance status, OSA severity, therapeutic pressure, or comorbid conditions were associated with pediatric CPAP adherence. Methods: A retrospective review of adherence download data was performed on all pediatric patients with initiation or adjustment of CPAP treatment over a one-year period with documented in-laboratory CPAP titration. Patients were grouped as CPAP adherent or non-adherent, where adherence was defined as > 70% nightly use and average usage ≥ 4 hours per night. Differences between the groups were analyzed by χ2 test. Results: Overall, nearly half of participants were CPAP adherent (49%, 69/140). Of the demographic data collected (age, ethnicity, sex, insurance status), only female sex was associated with better adherence (60.9% vs 39.5% of males adherent; odds ratio [OR] = 2.41, 95%CI = 1.20–4.85; p = 0.01). Severity of OSA (diagnostic apnea-hypopnea index [AHI] and degree of hypoxemia), therapeutic pressure, and residual AHI did not impact CPAP adherence (p > 0.05). Patients with developmental delay (DD) were more likely to be adherent with CPAP than those without a DD diagnosis (OR = 2.55, 95%CI = 1.27–5.13; p = 0.007). Female patients with trisomy 21 tended to be more adherent, but this did not reach significance or account for the overall increased adherence associated with female sex. Conclusions: Our study demonstrates that adherence to CPAP therapy is poor but suggests that female sex and developmental delay are associated with better adherence. These findings support efforts to understand the

  3. Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes

    NASA Astrophysics Data System (ADS)

    Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

    2016-08-01

    New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas.

  4. Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes

    PubMed Central

    Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

    2016-01-01

    New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas. PMID:27498607

  5. Concordance of adherence measurement using self-reported adherence questionnaires and medication monitoring devices.

    PubMed

    Shi, Lizheng; Liu, Jinan; Koleva, Yordanka; Fonseca, Vivian; Kalsekar, Anupama; Pawaskar, Manjiri

    2010-01-01

    The primary objective of this review was to identify and examine the literature on the association between medication adherence self-reported questionnaires (SRQs) and medication monitoring devices. The primary literature search was performed for 1980-2009 using PubMed, PubMed In Process and Non-Indexed, Ovid MEDLINE, Ovid MEDLINE In-Process, PsycINFO (EBSCO), CINAHL (EBSCO), Ovid HealthStar, EMBASE (Elsevier) and Cochrane Databases and using the following search terms: 'patient compliance', 'medication adherence', 'treatment compliance', 'drug monitoring', 'drug therapy', 'electronic', 'digital', 'computer', 'monitor', 'monitoring', 'drug', 'drugs', 'pharmaceutical preparations', 'compliance' and 'medications'. We identified studies that included SRQs and electronic monitoring devices to measure adherence and focused on the SRQs that were found to be moderately to highly correlated with the monitoring devices. Of the 1679 citations found via the primary search, 41 full-text articles were reviewed for correlation between monitoring devices and SRQs. A majority (68%) of articles reported high (27%), moderate (29%) or significant (12%) correlation between monitoring devices (37 using Medication Event Monitoring System [MEMS®] and four using other devices) and SRQs (11 identified and numerous other unnamed SRQs). The most commonly used SRQs were the Adult/Pediatric AIDS Clinical Trial Group (AACTG/PACTG; 24.4%, 10/41) followed by the 4-item Morisky (9.8%, 4/41), Brief Medication Questionnaire (9.8%, 4/41) and visual analogue scale (VAS; 7.3%, 3/41). Although study designs differed across the articles, SRQs appeared to report a higher rate of medication adherence (+14.9%) than monitoring devices. In conclusion, several medication adherence SRQs were validated using electronic monitoring devices. A majority of them showed high or moderate correlation with medication adherence measured using monitoring devices, and could be considered for measuring patient

  6. Synthesis of high thermally-stable mesoporous alumina particles.

    PubMed

    Song, Lee-Hwa; Park, Seung Bin

    2010-01-01

    The mesoporous undoped and Si-doped alumina were prepared with an ultrasonic spray process, and found to have well-developed mesopore structures and large surface areas. The mesoporous Si-doped alumina has a high thermal stability up to 1473 K. Its surface area and pore volume were found to slowly decrease with increasing temperature. Mesoporous undoped alumina is transformed to gamma-alumina at 1073 K, whereas the amorphous nature of the pore walls of the Si-doped alumina is maintained up to 1073 K. When heat treatment was carried out at 1473 K for 2 h, the mesopore-networks of the undoped alumina collapsed, and then all the pore walls were converted into the alpha-alumina phase. In contrast, the mesoporosity of the Si-doped alumina persisted during heat treatment, and its pore walls were transformed to gamma-alumina. The decreases in the pore volume of the undoped alumina at 1073 K and 1473 K were found to be 36% and 99% respectively, but for the Si-doped alumina were only 24% and 36% respectively. The surface area of the undoped alumina at 1473 K was found to be 11 m2/g but that of the Si-doped samples at the same temperature is higher than 100 m2/g. Thus this mesoporous Si-doped alumina can be used as a catalytic support in reactions at high temperatures.

  7. Adherence as a language game.

    PubMed

    Kolberg, Espen Skarstein

    2017-03-02

    Non-adherence, i.e. medication intake behavior not corresponding with agreed recommendations, is associated with increased morbidity and death, and it has been estimated that as many as 50% of patients in developed countries are not taking their medications as prescribed. But even as efforts in improving medication adherence over the years have increased, results are inconsistent, with only a minority of clinical trials showing any improvement in both adherence and clinical outcome. Since patient education is central to promoting good medication adherence, and language is integral to education, perhaps an exploration of the meaning and use of language, using the philosophy of Ludwig Wittgenstein, is in order.

  8. Dermatology patients’ and their doctors’ representations about adherence

    PubMed Central

    Kemény, Lajos; Csabai, Márta

    2015-01-01

    The aim of our study was to identify representations about patient adherence among dermatologists (N=40) and their patients (N=153). A combined qualitative-quantitative methodology was applied. Dermatologists identified good doctor-patient relationship, information from the doctor, and background information as the most important determinants of adherence. In patients’ rankings, information from the doctor and understandable communication received the highest scores. Multidimensional scaling arranged patients’ results into four content groups which helped to reveal the structure of the representations. Our results may contribute to the evidence-based confirmation that transparency of views and expectations in doctor-patient communication is a basic determinant of successful adherence. PMID:28352698

  9. Evaluation of Alumina-Forming Austenitic Foil for Advanced Recuperators

    SciTech Connect

    Pint, Bruce A; Brady, Michael P; Yamamoto, Yukinori; Santella, Michael L; Maziasz, Philip J; Matthews, Wendy

    2011-01-01

    A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. By optimizing the Al and Cr contents, the alloy is fully austenitic for creep strength while allowing the formation of a chemically stable external alumina scale at temperatures up to 900 C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. As a first step in producing foil for primary surface recuperators, three commercially cast heats have been rolled to 100 m thick foil in the laboratory to evaluate performance in creep and oxidation testing. Results from initial creep testing are presented at 675 C and 750 C, showing excellent creep strength compared with other candidate foil materials. Laboratory exposures in humid air at 650 800 C have shown acceptable oxidation resistance. A similar oxidation behavior was observed for sheet specimens of these alloys exposed in a modified 65 kW microturbine for 2871 h. One composition that showed superior creep and oxidation resistance has been selected for the preparation of a commercial batch of foil. DOI: 10.1115/1.4002827

  10. Dielectric Performance of a High Purity HTCC Alumina at High Temperatures - a Comparison Study with Other Polycrystalline Alumina

    NASA Technical Reports Server (NTRS)

    Chen, Liangyu

    2014-01-01

    A very high purity (99.99+%) high temperature co-fired ceramic (HTCC) alumina has recently become commercially available. The raw material of this HTCC alumina is very different from conventional HTCC alumina, and more importantly there is no glass additive in this alumina material for co-firing processing. Previously, selected HTCC and LTCC (low temperature co-fired ceramic) alumina materials were evaluated at high temperatures as dielectric and compared to a regularly sintered 96% polycrystalline alumina (96% Al2O3), where 96% alumina was used as the benchmark. A prototype packaging system based on regular 96% alumina with Au thickfilm metallization successfully facilitated long term testing of high temperature silicon carbide (SiC) electronic devices for over 10,000 hours at 500 C. In order to evaluate this new high purity HTCC alumina for possible high temperature packaging applications, the dielectric properties of this HTCC alumina substrate were measured and compared with those of 96% alumina and a previously tested LTCC alumina from room temperature to 550 C at frequencies of 120 Hz, 1 KHz, 10 KHz, 100 KHz, and 1 MHz. A parallel-plate capacitive device with dielectric of the HTCC alumina and precious metal electrodes were used for measurements of the dielectric constant and dielectric loss of the co-fired alumina material in the temperature and frequency ranges. The capacitance and AC parallel conductance of the capacitive device were directly measured by an AC impedance meter, and the dielectric constant and parallel AC conductivity of the dielectric were calculated from the capacitance and conductance measurement results. The temperature and frequency dependent dielectric constant, AC conductivity, and dissipation factor of the HTCC alumina substrate are presented and compared to those of 96% alumina and a selected LTCC alumina. Other technical advantages of this new co-fired material for possible high packaging applications are also discussed.

  11. Clonogenic Assay: Adherent Cells

    PubMed Central

    Rafehi, Haloom; Orlowski, Christian; Georgiadis, George T.; Ververis, Katherine; El-Osta, Assam; Karagiannis, Tom C.

    2011-01-01

    The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. Apart from documenting the method, the initial landmark study generated the first radiation-dose response curve for X-ray irradiated mammalian (HeLa) cells in culture1. Basically, the clonogenic assay enables an assessment of the differences in reproductive viability (capacity of cells to produce progeny; i.e. a single cell to form a colony of 50 or more cells) between control untreated cells and cells that have undergone various treatments such as exposure to ionising radiation, various chemical compounds (e.g. cytotoxic agents) or in other cases genetic manipulation. The assay has become the most widely accepted technique in radiation biology and has been widely used for evaluating the radiation sensitivity of different cell lines. Further, the clonogenic assay is commonly used for monitoring the efficacy of radiation modifying compounds and for determining the effects of cytotoxic agents and other anti-cancer therapeutics on colony forming ability, in different cell lines. A typical clonogenic survival experiment using adherent cells lines involves three distinct components, 1) treatment of the cell monolayer in tissue culture flasks, 2) preparation of single cell suspensions and plating an appropriate number of cells in petri dishes and 3) fixing and staining colonies following a relevant incubation period, which could range from 1-3 weeks, depending on the cell line. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cell lines with the use of an immortalized human keratinocyte cell line (FEP-1811)2. Also, our aims are to describe common features of clonogenic assays including calculation of the plating efficiency and survival fractions after exposure of cells to radiation, and to exemplify modification of radiation-response with the use of a natural antioxidant

  12. Iron films deposited on porous alumina substrates

    NASA Astrophysics Data System (ADS)

    Yamada, Yasuhiro; Tanabe, Kenichi; Nishida, Naoki; Kobayashi, Yoshio

    2016-12-01

    Iron films were deposited on porous alumina substrates using an arc plasma gun. The pore sizes (120 - 250 nm) of the substrates were controlled by changing the temperature during the anodic oxidation of aluminum plates. Iron atoms penetrated into pores with diameters of less than 160 nm, and were stabilized by forming γ-Fe, whereas α-Fe was produced as a flat plane covering the pores. For porous alumina substrates with pore sizes larger than 200 nm, the deposited iron films contained many defects and the resulting α-Fe had smaller hyperfine magnetic fields. In addition, only a very small amount of γ-Fe was obtained. It was demonstrated that the composition and structure of an iron film can be affected by the surface morphology of the porous alumina substrate on which the film is grown.

  13. Factors affecting medication adherence in elderly people

    PubMed Central

    Jin, Hyekyung; Kim, Yeonhee; Rhie, Sandy Jeong

    2016-01-01

    Background Little is known about the functional health literacy (FHL) associated with medication adherence in elderly patients. The aim of this study was to examine the FHL among older adults and identify influencing factors that can predict medication adherence. Methods This was a cross-sectional survey. Participants (n=160) aged 65 years and older were selected from outpatient clinics of 3 tertiary care hospitals, 6 community pharmacies, and 2 senior centers between November 1 and 30, 2014. The participants’ FHL was measured using the Korean Functional Health Literacy Test, which consists of 15 items including 8 numeracy and 7 reading comprehension items. Medication adherence was measured by the Adherence to Refills and Medication Scale. Descriptive statistics, chi-square or Fisher’s exact test, and multiple regression analyses were used to analyze the data. Results The mean score of the total FHL was 7.72±3.51 (range 0–15). The percentage of the total number of correct answers for the reading comprehension subtest and numeracy subtest were 48.1% and 54.4%, respectively. Among 160 participants, 52.5% showed low adherence to medication. The factors affecting medication adherence included the patient’s degree of satisfaction with the service (β=−0.215, P=0.022), sufficient explanation of medication counseling (β=−0.335, P=0.000), education level (β=−0.153, P=0.045), health-related problems (β=−0.239, P=0.004), and dosing frequency (β=0.189, P=0.018). Conclusion In this study, we found medication adherence of elderly patients was associated with education level, health-related problems, dosing frequency, satisfaction with patient counseling, and explanation of medication, but no association was found with FHL. Pharmacists should consider elderly patients’ individual characteristics such as educational background and specific patient-related health problems, provide sufficient information and explanation of medication, and ensure patient

  14. Biologic Influences on Exercise Adherence.

    ERIC Educational Resources Information Center

    Dishman, Rod K.

    1981-01-01

    Diagnostic profiles of 362 male participants in an exercise program were analyzed to determine the biological variables between exercise adherence and symptoms of coronary disease. Findings indicated that individuals with lower metabolic capacity tended to adhere longer, to be less fit, were leaner, and began with more symptoms related to coronary…

  15. Antidepressant adherence after psychiatric hospitalization

    PubMed Central

    Zivin, Kara; Ganoczy, Dara; Pfeiffer, Paul N.; Miller, Erin M.; Valenstein, Marcia

    2010-01-01

    Objective Depressed patients discharged from psychiatric hospitalizations face increased risks for adverse outcomes including suicide, yet antidepressant adherence rates during this high-risk period are unknown. Using Veterans Affairs (VA) data, we assessed antidepressant adherence and predictors of poor adherence among depressed veterans following psychiatric hospitalization. Method We identified VA patients nationwide with depressive disorders who had a psychiatric hospitalization between April 1, 1999 and September 30, 2003, received antidepressant medication, and had an outpatient appointment following discharge. We calculated medication possession ratios (MPRs), a measure of medication adherence, within three and six months following discharge. We assessed patient factors associated with having lower levels of adherence (MPRs <0.8) after discharge. Results 20,931 and 23,182 patients met criteria for three and six month MPRs. The mean three month MPR was 0.79 (s.d.=0.37). The mean six month MPR was 0.66 (s.d.=0.40). Patients with poorer adherence were male, younger, non-white, and had a substance abuse disorder, but were less likely to have PTSD or other anxiety disorders. Conclusion Poor antidepressant adherence is common among depressed patients after psychiatric hospitalization. Efforts to improve adherence at this time may be critical in improving the outcomes of these high-risk patients. PMID:19609666

  16. Treatment adherence in multiple sclerosis: a survey of Belgian neurologists

    PubMed Central

    Decoo, Danny; Vokaer, Mathieu

    2015-01-01

    Background Poor treatment adherence is common among patients with multiple sclerosis (MS). This survey evaluated neurologists’ perception of treatment adherence among MS patients. Materials and methods This questionnaire-based survey of Belgian neurologists treating MS patients was conducted between June and July 2014. Face-to-face interviews with the neurologists were based on a semistructured questionnaire containing questions regarding the perception of the treatment-adherence level. Results A total of 41 neurologists participated in the survey. Of these, 88% indicated frequent discussions about treatment adherence as beneficial for treatment efficacy. The mean time spent on the treatment-adherence discussion during the initial consultation was 11 minutes, with 24% of doctors spending 5 minutes and 24% of doctors spending 10 minutes discussing this issue. The majority of neurologists (56%) perceived the adherence level in MS as good, and 12% perceived it as excellent. The majority of neurologists (64%) indicated intolerance as a main cause of poor adherence, and all neurologists reported insufficient efficacy as a consequence of nonadherence. The importance of adherence in the neurologists’ practice was evaluated on a scale of 1–10, with 1= “not very important” and 10= “very important”: 44% of doctors indicated a score of 10, and the mean score was 9.0. Conclusion Belgian neurologists consider treatment adherence in MS as essential for the benefits of therapies. However, although neurologists are aware of the consequences of nonadherence, they generally spend limited time discussing the importance of treatment adherence with their patients. PMID:26640373

  17. Interface Engineering in Alumina/Glass Composites

    DTIC Science & Technology

    1992-02-29

    BN coating applied to the fibers disappeared during the fabrication process. Coating thicknesses as much as 0.3 jim was found to be assimilated during...E-200 Alumina Fiber Tin Dioxide ’ -300 - PD - 166 coating,30 -1(0.8 un) -400 00, -600 " 9.4 9.6 9.S 10.0 10.2 r ( jim ) Fig. 2. Fracture surface of...of the specimens Chemical composition’(wt.%) were polished, with 0.5 jim alumina powder, to mini- .i. 71 mize surface flaw effects. Strengih

  18. Contact Noise in Sodium Beta Alumina.

    DTIC Science & Technology

    1987-05-01

    AD-Al~i 128 CONTACT NOISE IN SODIUM BETA ALUMINA(U) UTANHUNIV SALT i/i LAKE CITY DEPT OF PHYSICS C K KUD ET AL MAY 87 UN SLR55IF IED FG 1,b2 NL UN...by Chu Kun Kuo* and James J. Brophy Physics Department University of Utah Salt Lake City, Utah 84112 ABSTRACT/ Contact noise in sodium 0alumina cells...ZIPCo*I) UNIVERSITY OF UTAH UNIVERISTY OF NEW MEXICO SALT LAKE CITY UT 84112 Bandelier Hall West Alhkq..u u. m (1 71-11 so NAME of FUNDING /SPONSORING Sb

  19. Current Noise in Sodium Beta Alumina Ceramic.

    DTIC Science & Technology

    1983-11-01

    7 ’FD-i49 549 CURRENT NOISE IN SODIUM BET ALUMINA CERAIC(U) UTAH i/iUNIV SALT LAKE CITY DEPT OF PHYSICS J J BROPHY ET AL.NOV 83 TR-5 N08814-82-K...REPORT NO. 5 CURRENT NOISE IN SODIUM 0" ALUMINA CERAMIC ID by James J. Brophy and Steven W. Smith * Prepared for Publication in the Journal of Applied...Physics D T IC ELECTE JAIN 1 Department of Physics $ ) University of Utah Salt Lake City, Utah 84112 November 1983 Reproduction in whole or in part is

  20. Chlorination of alumina in kaolinitic clay

    NASA Astrophysics Data System (ADS)

    Grob, B.; Richarz, W.

    1984-09-01

    The chlorination of alumina in kaolinitic clay with Cl2 and CO gas mixtures was studied gravimetrically. The effects of the calcination method and of NaCl addition on the reactivity of the clay were examined. Fast reaction rates were achieved only with samples previously exposed to a sulfating treatment. Optimum conditions, with maximum yield and selectivity to A1C13 and minimum SiO2 conversion, were found between 770 and 970 K. At higher temperatures the SiCl4 formed poisons the reactive alumina surface by selective chemisorption with a marked decrease of the reaction rate.

  1. REMOVING RADIUM FROM WATER BY PLAIN AND TREATED ACTIVATED ALUMINA

    EPA Science Inventory

    The research determined the feasibility of using BaSO4-impregnated activated alumina and plain activated alumina for radium removal from groundwater by fixed-bed adsorption. The major factors influencing radium adsorption onto the two types of alumina were identified. The radium ...

  2. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white,...

  3. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white,...

  4. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white,...

  5. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white,...

  6. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Alumina (dried aluminum hydroxide). 73.1010... GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried aluminum hydroxide). (a) Identity. (1) The color additive alumina (dried aluminum hydroxide) is a white,...

  7. [Strategies to improve medication adherence].

    PubMed

    Laufs, U; Böhm, M; Kroemer, H K; Schüssel, K; Griese, N; Schulz, M

    2011-08-01

    Up to 50 % of patients with chronic diseases do not take their medication regularly. Poor adherence to drug therapy is associated with higher morbidity and mortality. A selective literature search using the terms adherence, compliance, concordance, persistence, medication management, and pharmaceutical care was performed. Evidence for improving adherence has been provided for the following principles: individual counselling of patients and care givers, medication management including simplifying dosing and use of combination tablets as well as the use of individual unit doses, e. g. blister cards. The effectiveness has only been shown for the duration of the interventions. The improvement of medication adherence represents an area of research with high impact on outcomes and cost. Measures to improve adherence may be as important as the development of novel therapies. However, prospective clinical evaluations with clinical endpoints are missing especially for the German health care system in order to develop recommendations for clinical practice. Joint efforts of physicians and pharmacists are needed.

  8. The effects of water vapor on the oxidation behavior of alumina forming austenitic stainless steels

    DOE PAGES

    Yanar, N. M.; Lutz, B. S.; Garcia-Fresnillo, L.; ...

    2015-08-19

    The isothermal oxidation behavior of three alumina forming austenitic (AFA) stainless steels with varying composition was studied at 650 and 800 °C in dry air and gases which contained water vapor. The AFA alloys exhibited better oxidation resistance than a “good chromia former” at 650 °C, particularly in H2O-containing atmospheres by virtue of alumina-scale formation. Although the AFA alloys were more resistant than chromia formers, their oxidation resistance was degraded at 650 °C in the presence of water vapor. In dry air the AFA alloys formed, thin continuous alumina scales, whereas in Ar–4%H2–3%H2O the areas of continuous alumina were reducedmore » and Fe oxide-rich nodules and regions of Cr, Mn-rich oxides formed. In some regions internal oxidation of the aluminum occurred in the H2O-containing gas. The alloy OC8 had slightly better resistance than OC4 or OC5 in this atmosphere. The alumina-forming capability of the AFA alloys decreases with increasing temperature and, at 800 °C, they are borderline alumina formers, even in dry air. The oxidation resistance of all three alloys was degraded at 800 °C in atmospheres, which contained water vapor (Air–10%H2O, Ar–3%H2O and Ar–4%H2–3%H2O). The areas, which formed continuous alumina, were reduced in these atmospheres and areas of internal oxidation occurred. However, as a result of the borderline alumina-forming capability of the AFA alloys it was not possible to determine which of the H2O-containing atmospheres was more severe or to rank the alloys in terms of their performance. The experimental results indicate that the initial microstructure of the AFA alloys also plays a role in their oxidation performance. Less protective oxides formed at 800 °C when alloy OC8 was equilibrated before exposure rather than being exposed in the as-processed condition. As a result, the reason for this is the presence of different phases in the bulk of the two specimens.« less

  9. The effects of water vapor on the oxidation behavior of alumina forming austenitic stainless steels

    SciTech Connect

    Yanar, N. M.; Lutz, B. S.; Garcia-Fresnillo, L.; Brady, Michael P.; Meier, G. H.

    2015-08-19

    The isothermal oxidation behavior of three alumina forming austenitic (AFA) stainless steels with varying composition was studied at 650 and 800 °C in dry air and gases which contained water vapor. The AFA alloys exhibited better oxidation resistance than a “good chromia former” at 650 °C, particularly in H2O-containing atmospheres by virtue of alumina-scale formation. Although the AFA alloys were more resistant than chromia formers, their oxidation resistance was degraded at 650 °C in the presence of water vapor. In dry air the AFA alloys formed, thin continuous alumina scales, whereas in Ar–4%H2–3%H2O the areas of continuous alumina were reduced and Fe oxide-rich nodules and regions of Cr, Mn-rich oxides formed. In some regions internal oxidation of the aluminum occurred in the H2O-containing gas. The alloy OC8 had slightly better resistance than OC4 or OC5 in this atmosphere. The alumina-forming capability of the AFA alloys decreases with increasing temperature and, at 800 °C, they are borderline alumina formers, even in dry air. The oxidation resistance of all three alloys was degraded at 800 °C in atmospheres, which contained water vapor (Air–10%H2O, Ar–3%H2O and Ar–4%H2–3%H2O). The areas, which formed continuous alumina, were reduced in these atmospheres and areas of internal oxidation occurred. However, as a result of the borderline alumina-forming capability of the AFA alloys it was not possible to determine which of the H2O-containing atmospheres was more severe or to rank the alloys in terms of their performance. The experimental results indicate that the initial microstructure of the AFA alloys also plays a role in their oxidation performance. Less protective oxides formed at 800 °C when alloy OC8 was equilibrated before exposure rather than being exposed in the as-processed condition. As a result, the reason for this is the presence of different

  10. Dielectric breakdown of polycrystalline alumina: A weakest-link failure analysis

    NASA Astrophysics Data System (ADS)

    Block, Benjamin

    The effects of varying electrode geometry (ball and ring) and size (radius), dielectric media (castor oil and DialaRTM oil), specimen thickness, and concentration of defects on the dielectric breakdown strength of commercial-grade alumina and high-purity fine-grained (HPFG) alumina were investigated. The breakdown strength was expressed in terms of the maximum electric field in the ceramic at the breakdown voltage calculated by finite element analysis (FEA). The breakdown strength decreased systematically with increasing electrode radius and specimen thickness. The breakdown strength increased with decreasing concentration of defects. The breakdown strength was higher in the Diala RTM oil (dielectric constant, epsilonr = 2.3 +/- 0.12) as compared to the castor oil (epsilonr = 4.59 +/- 0.06). The breakdown strength was higher for the HPFG alumina as compared to the commercial- grade alumina. These effects of the electrode geometry, specimen thickness, concentration of defects, and of the dielectric media were analyzed with a weakest-link failure model employing the Laplace and Weibull distributions for a population of defects in the material. The measured size or scaling effects of the electrodes, specimen thickness, concentration of defects, and of the liquid media on breakdown strength were in better agreement with the Laplace distribution for the population. The measured concentration of surface defects was in good agreement with the concentration of surface defects estimated from the surface area scaling of the breakdown field with the Laplace distribution.

  11. Morbidly adherent placenta.

    PubMed

    Abuhamad, Alfred

    2013-10-01

    Morbidly adherent placenta, which describes placenta accreta, increta, and percreta, implies an abnormal implantation of the placenta into the uterine wall. The incidence of placenta accreta has increased significantly over the past several decades, with the main risk factors include prior cesarean section and placental previa. Sonographic markers of placenta accreta can be present as early as the first trimester and include a low uterine implantation of a gestational sac, multiple vascular lacunae within the placenta, loss of the normal hypoechoic retroplacental zone, and abnormality of the uterine serosa-bladder interface, among others. Ultrasound has high sensitivity and specificity for the diagnosis of placenta accreta and MRI should be reserved for rare cases in which the ultrasound is non-diagnostic. The optimum time for planned delivery for a patient with placenta accreta is around 34-35 weeks following a course of corticosteroid injection. The successful management of placenta accreta includes a multidisciplinary care team approach with the successful management relying heavily on the prenatal diagnosis of this entity and preparing for the surgical management in a multidisciplinary approach by assuring the most skilled team is available for those patients.

  12. Thermal Conductivity of Alumina-Toughened Zirconia Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Zhu, Dong-Ming

    2003-01-01

    10-mol% yttria-stabilized zirconia (10YSZ)-alumina composites containing 0 to 30 mol% alumina were fabricated by hot pressing at 1500 C in vacuum. Thermal conductivity of the composites, determined at various temperatures using a steady-state laser heat flux technique, increased with increase in alumina content. Composites containing 0, 5, and 10-mol% alumina did not show any change in thermal conductivity with temperature. However, those containing 20 and 30-mol% alumina showed a decrease in thermal conductivity with increase in temperature. The measured values of thermal conductivity were in good agreement with those calculated from simple rule of mixtures.

  13. Reinforcing adherence to antihypertensive medications.

    PubMed

    Petry, Nancy M; Alessi, Sheila M; Byrne, Shannon; White, William B

    2015-01-01

    This pilot study evaluated a reinforcement intervention to improve adherence to antihypertensive therapy. Twenty-nine participants were randomized to standard care or standard care plus financial reinforcement for 12 weeks. Participants in the reinforcement group received a cell phone to self-record videos of adherence, for which they earned rewards. These participants sent videos demonstrating on-time adherence 97.8% of the time. Pill count adherence differed significantly between the groups during treatment, with 98.8%±1.5% of pills taken during treatment in the reinforcement condition vs 92.6%±9.2% in standard care (P<.002). Benefits persisted throughout a 3-month follow-up, with 93.8%±9.3% vs 78.0%±18.5% of pills taken (P<.001). Pill counts correlated significantly (P<.001) with self-reports of adherence, which also differed between groups over time (P<.01). Systolic blood pressure decreased modestly over time in participants overall (P<.01) but without significant time-by-group effects. These results suggest that reinforcing medication adherence via cellular phone technology and financial reinforcement holds potential to improve adherence.

  14. Dielectric Performance of High Purity HTCC Alumina at High Temperatures - A Comparison Study with Other Polycrystalline Alumina

    NASA Technical Reports Server (NTRS)

    Chen, Liang-Yu

    2012-01-01

    A very high purity (99.99+) high temperature co-fired ceramic (HTCC) alumina has recently become commercially available. The raw material of this HTCC alumina is very different from conventional HTCC alumina, and more importantly there is no glass additive in this co-fired material. Previously, selected HTCC and LTCC (low temperature co-fired ceramic) alumina materials were evaluated at high temperatures as dielectric and compared to a regularly sintered 96 polycrystalline alumina (96 Al2O3), where 96 alumina was used as the benchmark. A prototype packaging system based on regular 96 alumina with Au thick-film metallization successfully facilitated long term testing of high temperature silicon carbide (SiC) electronic devices for over 10,000 hours at 500C. In order to evaluate this new HTCC alumina for possible high temperature packaging applications, the dielectric properties of this HTCC alumina substrate were measured and compared with those of 96 alumina and a LTCC alumina from room temperature to 550C at frequencies of 120 Hz, 1 KHz, 10 KHz, 100 KHz, and 1 MHz. A parallel-plate capacitive device with dielectric of the HTCC alumina and precious metal electrodes were used for measurements of the dielectric constant and dielectric loss of the co-fired alumina material in the temperature and frequency ranges. The capacitance and AC parallel conductance of the capacitive device were directly measured by an AC impedance meter, and the dielectric constant and parallel AC conductivity of the dielectric were calculated from the capacitance and conductance measurement results. The temperature and frequency dependent dielectric constant, AC conductivity, and dissipation factor of the HTCC alumina substrate are presented and compared to those of 96 alumina. Other technical advantages of this new co-fired material for possible high packaging applications are also discussed.

  15. Study of alumina-trichite reinforcement of a nickel-based matric by means of powder metallurgy

    NASA Technical Reports Server (NTRS)

    Walder, A.; Hivert, A.

    1982-01-01

    Research was conducted on reinforcing nickel based matrices with alumina trichites by using powder metallurgy. Alumina trichites previously coated with nickel are magnetically aligned. The felt obtained is then sintered under a light pressure at a temperature just below the melting point of nickel. The halogenated atmosphere technique makes it possible to incorporate a large number of additive elements such as chromium, titanium, zirconium, tantalum, niobium, aluminum, etc. It does not appear that going from laboratory scale to a semi-industrial scale in production would create any major problems.

  16. Measuring insulin adherence among adults with type 2 diabetes.

    PubMed

    Osborn, Chandra Y; Gonzalez, Jeffery S

    2016-08-01

    Non-adherence to insulin is common and associated with suboptimal health. We adapted the Morisky Medication Adherence Scale to specify insulin adherence (MIAS) and compared it to the Adherence to Refills and Medication Scale for Diabetes (ARMS-D) and the Summary of Diabetes Self-Care Activities medications subscale (SDSCA-MS) and an insulin-specific (SDSCA-IS) version. A sample of 144 insulin-treated adults (58 % African American/Black, 34 % Caucasian/White, 8 % Other/Mixed race; 6.9 % Hispanic) completed these measures along with a HbA1C test. The internal consistency and factor structure of the MIAS were adequate; 59 % of participants forgot to take insulin and 46 % reported non-adherence. The MIAS was associated with the ARMS-D, SDSCA-MS, and SDSCA-IS (p < 0.001), and higher MIAS scores were marginally associated with better self-rated health (p = 0.057), but significantly associated with fewer emergency room visits (p = 0.001), and better HbA1C (p = 0.001). The MIAS is a valid and reliable insulin adherence assessment tool for practice and research applications.

  17. Proton-conducting beta"-alumina via microwave-assisted synthesis and mechanism of enhanced corrosion prevention of a zinc rich coating with electronic control

    NASA Astrophysics Data System (ADS)

    Kirby, Brent William

    . The barrier layer is denser and more adherent with the ECU in place. A mechanism is proposed in which the characteristic time constant of the ECU is roughly matched to the time scale of ionic motion within the coating. The capacitive nature of the ECU retards the motion of ions, and affects the formation of denser corrosion products.

  18. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    SciTech Connect

    Li, Chuanping

    2004-01-01

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the 17O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles

  19. Medication Adherence Measures: An Overview.

    PubMed

    Lam, Wai Yin; Fresco, Paula

    2015-01-01

    WHO reported that adherence among patients with chronic diseases averages only 50% in developed countries. This is recognized as a significant public health issue, since medication nonadherence leads to poor health outcomes and increased healthcare costs. Improving medication adherence is, therefore, crucial and revealed on many studies, suggesting interventions can improve medication adherence. One significant aspect of the strategies to improve medication adherence is to understand its magnitude. However, there is a lack of general guidance for researchers and healthcare professionals to choose the appropriate tools that can explore the extent of medication adherence and the reasons behind this problem in order to orchestrate subsequent interventions. This paper reviews both subjective and objective medication adherence measures, including direct measures, those involving secondary database analysis, electronic medication packaging (EMP) devices, pill count, and clinician assessments and self-report. Subjective measures generally provide explanations for patient's nonadherence whereas objective measures contribute to a more precise record of patient's medication-taking behavior. While choosing a suitable approach, researchers and healthcare professionals should balance the reliability and practicality, especially cost effectiveness, for their purpose. Meanwhile, because a perfect measure does not exist, a multimeasure approach seems to be the best solution currently.

  20. Medication Adherence Measures: An Overview

    PubMed Central

    Lam, Wai Yin; Fresco, Paula

    2015-01-01

    WHO reported that adherence among patients with chronic diseases averages only 50% in developed countries. This is recognized as a significant public health issue, since medication nonadherence leads to poor health outcomes and increased healthcare costs. Improving medication adherence is, therefore, crucial and revealed on many studies, suggesting interventions can improve medication adherence. One significant aspect of the strategies to improve medication adherence is to understand its magnitude. However, there is a lack of general guidance for researchers and healthcare professionals to choose the appropriate tools that can explore the extent of medication adherence and the reasons behind this problem in order to orchestrate subsequent interventions. This paper reviews both subjective and objective medication adherence measures, including direct measures, those involving secondary database analysis, electronic medication packaging (EMP) devices, pill count, and clinician assessments and self-report. Subjective measures generally provide explanations for patient's nonadherence whereas objective measures contribute to a more precise record of patient's medication-taking behavior. While choosing a suitable approach, researchers and healthcare professionals should balance the reliability and practicality, especially cost effectiveness, for their purpose. Meanwhile, because a perfect measure does not exist, a multimeasure approach seems to be the best solution currently. PMID:26539470

  1. Scales

    MedlinePlus

    Scales are a visible peeling or flaking of outer skin layers. These layers are called the stratum ... Scales may be caused by dry skin, certain inflammatory skin conditions, or infections. Eczema , ringworm , and psoriasis ...

  2. Suboptimal treatment adherence in bipolar disorder: impact on clinical outcomes and functioning

    PubMed Central

    Montes, Jose Manuel; Maurino, Jorge; de Dios, Consuelo; Medina, Esteban

    2013-01-01

    Background The primary aim of this study was to assess drug treatment adherence in patients with bipolar disorder and to identify factors associated with adherence. The secondary aim was to analyze the impact of suboptimal adherence on clinical and functional outcomes. Methods A cross-sectional study was conducted in a sample of outpatients receiving an oral antipsychotic drug. Medication adherence was assessed combining the 10-item Drug Attitude Inventory, the Morisky Green Adherence Questionnaire, and the Compliance Rating Scale. Logistic regression was used to determine significant variables associated with suboptimal adherence to medication. Results Three hundred and three patients were enrolled into the study. The mean age was 45.9 ± 12.8 years, and 59.7% were females. Sixty-nine percent of patients showed suboptimal adherence. Disease severity and functioning were significantly worse in the suboptimal group than in the adherent group. Multivariate analysis showed depressive polarity of the last acute episode, presence of subsyndromal symptoms, and substance abuse/dependence to be significantly associated with suboptimal treatment adherence (odds ratios 3.41, 2.13, and 1.95, respectively). Conclusion A high prevalence of nonadherence was found in an outpatient sample with bipolar disorder. Identification of factors related to treatment adherence would give clinicians the opportunity to select more adequately patients who are eligible for potential adherence-focused interventions. PMID:23378745

  3. Adherence to highly active antiretroviral therapy in Hyderabad, India: barriers, facilitators and identification of target groups.

    PubMed

    Dworkin, Mark S; Douglas, G W; Sabitha Rani, G P; Chakraborty, Apurba

    2016-03-01

    We assessed the barriers and facilitators to highly active antiretroviral therapy adherence and determined their prevalence among HIV/AIDS patients in Hyderabad, India. We conducted a cross-sectional study among HIV-infected adults prescribed highly active antiretroviral therapy and receiving care from nine clinics. Depression was screened using Patient Health Questionnaire 9 and facilitators of HIV medication adherence were assessed using an 11-item scale which yielded a total positive attitude to disease score. Prevalence ratios of non-adherence between different categories of potential risk factors were calculated. We compared mean 'facilitators to adherence' scores between the adherent and non-adherent population. Multivariable Poisson regression with robust variance was used to identify independent risk factors. Among the 211 respondents, nearly 20% were non-adherent, approximately 8% had either moderately severe or severe depression and mean score for combined facilitators to medication adherence was 33.35 (±7.88) out of a possible 44 points. Factors significantly associated with non-adherence included older age, female sex worker, moderate-to-severe depression and the combined facilitators to medication adherence score. These data from a broad range of clinical settings in Hyderabad reveal that key groups to focus on for adherence intervention are female sex workers, older persons and those with depression.

  4. Microwave joining of high-purity alumina

    SciTech Connect

    Cozzi, A.D.; Clark, D.E.; Ferber, M.K.

    1996-12-31

    Microwave hybrid heating (MHH) was used to join 99.5% pure alumina pieces 25 mm diameter and 25 mm long using 94% pure alumina as the interlayer material. The interlayer material was cut from a rod into discs approximately 2 mm thick. Joining was performed in a home model microwave oven. Temperatures for joining ranged from 1450{degrees}C to 1550{degrees}C and pressures from 1-3 MPa. For comparison, similar joints were made in a conventional furnace. Joined specimens were tested using four-point bend at room temperature. Statistical analysis was utilized to determine the relative effect of the different processing parameters on the strength of the joint.

  5. Li + ion diffusion in nanoscale alumina coatings

    NASA Astrophysics Data System (ADS)

    Johannes, Michelle; Bernstein, Noam

    Nanoscale coatings of alumina are used to stabilize surfaces for a variety of technologies. Diffusion of ions through these coatings is of primary importance: in some cases, diffusion is unwanted (e.g. corrosion) and in others (e.g. electrode materials), it is necessary. In this work DFT and AIMD calculations are used to investigate Li+ ion diffusion through a nano-layer of alumina, examining the phase (alpha, gamma, and amorphous), ion concentration, and electron count dependence. We look at the role of the surface itself in promoting diffusion. One of our main findings is that as the number of ions or charge increases, the diffusivity rises. We show how our data can explain electrochemical data from coated LiCoO2 cathodes and may point toward better and more efficient coatings for stabilizing electrodes.

  6. Silica containing highly porous alumina ceramic

    NASA Astrophysics Data System (ADS)

    Svinka, R.; Svinka, V.; Zake, I.

    2011-04-01

    Porous alumina ceramic were produced by slip casting of aqueous alumina slurry with added small amount of metallic aluminium powder. Pores form in result of chemical reaction of aluminum with water by hydrogen gas evolution reaction and solidification of suspension. Porosity of such materials sintered at a temperature of 1600 - 1750°C varies from 60 to 90%. Pore size distribution and mechanical strength of these materials depend largely on the grain size of used raw materials. The major part of pores in the materials produced without additive of silica are larger than 10 ±m, but with 5 - 10 wt.% additive of silica in the raw mix pore size decreases considerably. The sintering shrinkage decreases to 2.5%. Coefficient of thermal expansion equally decreases from 8.9-10-6 K-1 to 7.1 10-6 K-1 and classification temperature increases to 1600°C, while deformation at high temperature decreases considerably.

  7. Activation of consolidation processes of alumina ceramics

    NASA Astrophysics Data System (ADS)

    Matrenin, S. V.; Zenin, B. S.; Tayukin, R. V.

    2016-02-01

    The methods for activating sintering ceramics based on Al2O3 by mechanical activation in the planetary mill, by adding in the mixture of nanopowders (NP) Al, Al2O3, and submicron powder TiO2, and by applying the technology of spark plasma sintering (SPS) are developed. It has been shown that adding the nanopowder up to 20 wt. % Al2O3 in a coarse powder α-Al2O3 activates the sintering process resulting in increased density and hardness of the sintered alumina ceramics. Substantial effect of increasing density of alumina ceramics due to adding the submicron powder TiO2 in the compound of initial powder mixtures has been established.

  8. Tribology of alumina-graphite composites

    NASA Astrophysics Data System (ADS)

    Yu, Chih-Yuan

    Alumina-graphite composites, which combine high wear resistance and self-lubricity, are a potential and promising candidate for advanced tribological applications. The processing, mechanical properties and tribology of alumina-graphite composites are discussed. Full density is difficult to achieve by a pressureless sintering route. Porosity of the composites increases with graphite content which causes the strength, modulus of elasticity, and hardness of the composites to decrease. The increased porosity does cause the fracture toughness to slightly increases. Tribology of alumina-graphite composites was studied with a pin-on-disk tribometer with emphasis on the following aspects: the graphite content in both pin and disk, the graphite flake size and the orientation of the graphite flakes. Scan electronic microscopy (SEM) and X-ray diffraction are utilized to examine and characterize the wear debris and the worn surface. Results confirmed that it is necessary to optimize the structure and the supply of lubricant to improve the tribological behavior and that the arrangements of sliding couples also affect the tribology of self-lubricated ceramic composites. Continuous measurements of the friction coefficients were collected at high frequency in an attempt to correlate the tribology of alumina-graphite composites to vibrations introduced by friction. While these measurements indicate that the time frequency behavior of tribology is an important area of study, conclusions regarding the frequency response of different sliding couples could not be definitively stated. Finally, a new concept connecting instantaneous wear coefficient and instantaneous contact stress is proposed for prediction of wear behavior of brittle materials.

  9. Decay of elastic waves in alumina

    NASA Astrophysics Data System (ADS)

    Marom, H.; Sherman, D.; Rosenberg, Z.

    2000-11-01

    The dynamic response of alumina under shock compression was studied using planar impact experiments with different tile thicknesses. Stress-time measurements were made with manganin gauges backed by different backing materials in order to optimize gauge response. The results show an apparent decay in the Hugoniot elastic limit with propagation distance. However, further analysis reveals that this phenomenon is probably a measurement artifact, resulting from the relatively slow response times of manganin gauges.

  10. Luminescence of Cu+ Beta’ Alumina.

    DTIC Science & Technology

    1987-07-01

    the ion exchange procedure using melts of pure cuprous salts often resulted in crystals which were discolored and which lumi- nesced only weakly...importance is the stabil- ity of the cuprous ions in the fil-alumina host. We have begun to explore some of these questions. Very high intensity UV radia...SCHEDULE dis tribut ion is unlimited 4. PERFORMING ORGANIZATION REPORT NUMBER(S) S. MONITORING ORGANIZATION REPORT NUMBER(S) Technical Report No. 12 Ga

  11. First principles study of oxygen diffusion in a α-alumina ? twin grain boundary

    NASA Astrophysics Data System (ADS)

    Tohei, Tetsuya; Watanabe, Yuito; Takahashi, Nobuaki; Nakagawa, Tsubasa; Shibata, Naoya; Ikuhara, Yuichi

    2015-12-01

    We have investigated atomistic scale behaviour of oxygen diffusion along the ? twin grain boundary in α-Al2O3 (alumina) using molecular dynamics simulation and first principles total energy calculations. Based on the GB structure model which is verified by atomic-scale STEM observations on the bicrystal sample, quantitative evaluation of migration energies for dominant migration paths were performed by atomistic calculations. The preset calculation results confirmed fast oxygen diffusion behaviour along the GB. Our analysis shows that the dominant migration path or difference in the migration energies can be well correlated with the geometry of local atomic coordination around the migrating oxygen; lower migration energies are generally expected for paths with less change in coordination environment on migration. This trend holds both among gain boundary paths and bulk paths in α-alumina examined in the present study.

  12. Compression Testing of Alumina Fiber Insulation

    NASA Technical Reports Server (NTRS)

    Vaughn, Wallace L.

    2006-01-01

    A series of tests were conducted to measure the response of alumina fiber insulation to compression loading. The alumina fiber insulation is a candidate gasket material for the Space Shuttle Government Furnished Equipment (GFE) Tile Overlay Repair. Tests were conducted at room temperature and 2300 F. The alumina fiber insulation is a fibrous insulation blanket which was supplied to Langley in two forms, a nominal 3 lb/ft3 version and a nominal 9 lb/ft3 version. The 3 lb/ft3 material was tested as sheets 0.15 and 0.25 inches thick and the 9 lb/ft3 material in sheets 1 inch thick. The material showed very non-linear compression behavior with the compressive resistance of the material increasing as the material was compressed. The 3 lb/ft3 0.15-inch thick material required 4.1 psi to reach the nominal installation thickness of 0.045 inches and retain a load of 2.1 lbs during unloading. Testing at 2300 F resulted in a stiffer more board-like material. The 3 lb/ft3 0.15-inch thick material retained 1 psi of compressive resistance after a 10 minute hold at 2300 F and 0.045 inches thickness.

  13. High contrast laser marking of alumina

    NASA Astrophysics Data System (ADS)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; del Val, J.; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-05-01

    Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks.

  14. The challenge of patient adherence

    PubMed Central

    Martin, Leslie R; Williams, Summer L; Haskard, Kelly B; DiMatteo, M Robin

    2005-01-01

    Quality healthcare outcomes depend upon patients' adherence to recommended treatment regimens. Patient nonadherence can be a pervasive threat to health and wellbeing and carry an appreciable economic burden as well. In some disease conditions, more than 40% of patients sustain significant risks by misunderstanding, forgetting, or ignoring healthcare advice. While no single intervention strategy can improve the adherence of all patients, decades of research studies agree that successful attempts to improve patient adherence depend upon a set of key factors. These include realistic assessment of patients' knowledge and understanding of the regimen, clear and effective communication between health professionals and their patients, and the nurturance of trust in the therapeutic relationship. Patients must be given the opportunity to tell the story of their unique illness experiences. Knowing the patient as a person allows the health professional to understand elements that are crucial to the patient's adherence: beliefs, attitudes, subjective norms, cultural context, social supports, and emotional health challenges, particularly depression. Physician–patient partnerships are essential when choosing amongst various therapeutic options to maximize adherence. Mutual collaboration fosters greater patient satisfaction, reduces the risks of nonadherence, and improves patients' healthcare outcomes. PMID:18360559

  15. Role of alumina phase and size in tungsten CMP

    SciTech Connect

    STEIN,DAVID J.; HER,ROBERT Y.-S.

    2000-02-01

    The role of the alumina particle phase and size on polish rate and process temperature was studied to elucidate removal mechanisms involved in tungsten CMP using potassium iodate-based slurries. Additional work including polishing of blanket PETEOS and titanium films, and polishing of M1 to V1 to M2 electrical test structures was performed to determine the performance of the various aluminas in production CMP. The polish rate of tungsten was highest with alpha alumina. Delta/theta and gamma alumina showed lower polish rates. Tungsten and PETEOS polish rates increased with particle size. Only alpha alumina was able to clear the titanium barrier stack. The size of the alpha alumina did not effect the electrical characteristics of short loop electrical test structures.

  16. A simple procedure to prepare spherical {alpha}-alumina powders

    SciTech Connect

    Liu Hongyu; Ning Guiling Gan Zhihong; Lin Yuan

    2009-04-02

    Spherical {alpha}-alumina powders were prepared by the controlled hydrolysis of aluminum isopropoxide in a hydrolysis system consisting of octanol and acetonitrile. Diverse solvents to dissolve reactant formed diverse hydrolysis systems and affected particle shape of {alpha}-alumina powders. The precursors crystallized to {gamma}-alumina at 1000 deg. C and converted to {alpha}-alumina at 1150 deg. C without intermediate phases. The particle morphology of precursor was retained after it crystallized to {alpha}-alumina. The heating rate influenced the particle shape and the state of agglomeration during calcination process. The thermal properties of the precursors were characterized by thermal gravimetric and differential thermal analysis. X-ray diffraction technique was used to confirm the conversion of crystalline phase of alumina powders from amorphous to {alpha}-phase. Transmission electron microscopy was used to investigate the morphologies and size of the precursors and products.

  17. Free-standing alumina nanobottles and nanotubes pre-integrated into nanoporous alumina membranes

    NASA Astrophysics Data System (ADS)

    Fang, Jinghua; Levchenko, Igor; (Ken Ostrikov, Kostya

    2014-08-01

    A novel interfacial structure consisting of long (up to 5 μm), thin (about 300 nm), highly-ordered, free-standing, highly-reproducible aluminum oxide nanobottles and long tubular nanocapsules attached to a rigid, thin (less than 1 μm) nanoporous anodic alumina membrane is fabricated by simple, fast, catalyst-free, environmentally friendly voltage-pulse anodization. A growth mechanism is proposed based on the formation of straight channels in alumina membrane by anodization, followed by neck formation due to a sophisticated voltage control during the process. This process can be used for the fabrication of alumina nanocontainers with highly controllable geometrical size and volume, vitally important for various applications such as material and energy storage, targeted drug and diagnostic agent delivery, controlled drug and active agent release, gene and biomolecule reservoirs, micro-biologically protected platforms, nano-bioreactors, tissue engineering and hydrogen storage.

  18. Free-standing alumina nanobottles and nanotubes pre-integrated into nanoporous alumina membranes

    PubMed Central

    Fang, Jinghua; Levchenko, Igor; Ostrikov, Kostya (Ken)

    2014-01-01

    A novel interfacial structure consisting of long (up to 5 μm), thin (about 300 nm), highly-ordered, free-standing, highly-reproducible aluminum oxide nanobottles and long tubular nanocapsules attached to a rigid, thin (less than 1 μm) nanoporous anodic alumina membrane is fabricated by simple, fast, catalyst-free, environmentally friendly voltage-pulse anodization. A growth mechanism is proposed based on the formation of straight channels in alumina membrane by anodization, followed by neck formation due to a sophisticated voltage control during the process. This process can be used for the fabrication of alumina nanocontainers with highly controllable geometrical size and volume, vitally important for various applications such as material and energy storage, targeted drug and diagnostic agent delivery, controlled drug and active agent release, gene and biomolecule reservoirs, micro-biologically protected platforms, nano-bioreactors, tissue engineering and hydrogen storage. PMID:27877705

  19. Role of Hf4+ Doping on Oxygen Grain Boundary Diffusion in Alumina

    DTIC Science & Technology

    2014-09-01

    Normal alloying elements presented in Ni-based superalloys [84] 8 Figure 1.2: Cross section view of thermal barrier coating system [3] 9...Schematic plot for Fisher’s model [109] 28 Figure 2.3: O concentration profile plot against depth x (cm) (68) 31 Figure 2.4: Oxygen grain...values of the parabolic rate constants for different samples xvui Abstract The growth of protective alumina scales in Al203-fonning alloys can be

  20. Change in organic molecule adhesion on α-alumina (sapphire) with change in NaCl and CaCl2 solution salinity.

    PubMed

    Juhl, K M S; Bovet, N; Hassenkam, T; Dideriksen, K; Pedersen, C S; Jensen, C M; Okhrimenko, D V; Stipp, S L S

    2014-07-29

    We investigated the adhesion of two functional groups to α-alumina as a model for the adsorption of organic molecules on clay minerals. Interactions between organic compounds and clay minerals play an important role in processes such as drinking water treatment, remediation of contaminated soil, oil recovery, and fabricating complicated nanomaterials, and there have been claims that organic compound-clay mineral interaction created the ordering that is necessary for the genesis of life. In many organisms, interaction between organic molecules and biominerals makes it possible to control the growth of bones, teeth, and shells. Adhesion of carboxylic acid, -COO(H), and pyridine, -C5H5N(H(+)), on the {0001} plane of α-alumina wafers has been investigated with atomic force microscopy (AFM) in chemical force mapping (CFM) mode. Both functional groups adhered to α-alumina in deionized water at pH < 5, and adhesion decreased as NaCl or CaCl2 concentration increased. X-ray photoelectron spectroscopy (XPS) showed that Na(+) and Ca(2+) adsorbed to the α-alumina surface at pH < 5, decreasing surface interaction with the carboxylic acid and pyridine groups. We interpret the results as evidence that the tips adhere to alumina through hydrogen bonding when only water is present. In solutions containing NaCl and CaCl2, cations are adsorbed but Cl(-) is not. When NaCl solutions are replaced by CaCl2, Ca(2+) replaces Na(+), but rinsing with ultrapure deionized water (pH 5.6) could not restore the original protonated surface. The results demonstrate that the alumina surface at pH 3 has a higher affinity for inorganic cations than for -COO(H) or -C5H5N(H(+)), in spite of the known positive surface charge of α-alumina {0001} wafers. These results demonstrate that solution salinity plays an important role in surface properties, controlling surface tension (i.e., contact angle) and adsorption affinity on α-alumina and, by analogy, on clay minerals.

  1. Method for preparing Pb-.beta."-alumina ceramic

    DOEpatents

    Hellstrom, Eric E.

    1986-01-01

    A process is disclosed for preparing impermeable, polycrystalline samples of Pb-.beta."-alumina ceramic from Na-.beta."-alumina ceramic by ion exchange. The process comprises two steps. The first step is a high-temperature vapor phase exchange of Na by K, followed by substitution of Pb for K by immersing the sample in a molten Pb salt bath. The result is a polycrystalline Pb-.beta."-alumina ceramic that is substantially crack-free.

  2. Plasma sintering of beta″-alumina

    NASA Astrophysics Data System (ADS)

    Henrichsen, Matthew

    Sintering and phase conversion of beta″-alumina were investigated with static and ultra-rapid passthrough plasma firing. Ultra-rapid passthrough induction firing was used to differentiate the effects of rapid heating rates from plasma effects. Static plasma sintering at low pressures resulted in excessive sodium loss which prohibited the use of dilatometry. Sintering was characterized using the diameter profiles of partially fired tubes. Phase conversion was examined with x-ray diffraction of powdered sections of partially fired tubes. Ultra-rapid passthrough firing speeds ranged from 8 to ˜240 mm/min. Instantaneous shrinkage rates as large as 8%/sec were measured. Phase conversion and sintering were both rapid, and were complete in seconds. Tubes with densities above 97%, beta″-phase content above 98%, and ionic resistivity as low as 13.8 Ocm were produced. Two modes of cracking were identified for tubes in ultra-rapid firing. Both were related to the thickness of the tube wall and sinterability of the powder being fired. A finite element model of sintering and heat transfer was developed to aid in determining the causes of cracking. Cracks formed because of mechanical stress rather than thermal shock. Low levels of cobalt in the precursor materials greatly reduced specimen heating in the plasma. The surface of beta″-alumina, like that of alpha-alumina, is catalytic for recombination of ions and radical components from the plasma. Induction furnace firing produced heating rates lower than those in plasma heating. Fired tubes were oversintered and had duplex microstructures. Some specimens fired in the induction furnace were contaminated by carbon from the graphite susceptor. Two peaks were observed in shrinkage rate profiles of some tubes. A model of dimensional change from simultaneous sintering and phase conversion was constructed. The model produced shrinkage rate profiles similar to those observed in both plasma and induction firing. The multiple peaks

  3. Sintering of beta-type alumina bodies using alpha-alumina encapsulation

    DOEpatents

    McEntire, Bryan J.; Virkar, Anil V.

    1981-01-01

    A method of sintering a shaped green, beta-type alumina body comprising: (A) inserting said body into an open chamber prepared by exposing the interior surface of a container consisting essentially of at least about 50 weight percent of alpha-alumina and a remainder of other refractory material to a sodium oxide or sodium oxide producing environment; (B) sealing the chamber; and heating the chamber with the shaped body encapsulated therein to a temperature and for a time necessary to sinter said body to the desired density. The encapsulation chamber prepared as described above is also claimed.

  4. Samarium and europium beta”-alumina derivatives characterized by XPS

    DOE PAGES

    Myhre, Kristian; Meyer, Harry; Du, Miting

    2017-01-04

    Characterization of sodium, samarium and europium beta -alumina derivatives has been carried out using X-ray photoelectron spectroscopy. Beta -alumina has been widely studied as a material capable of incorporating many different cations into its lattice structure, such as sodium and many of the lanthanide elements. The X-ray photoelectron spectra of samarium and europium in the beta -alumina structure are reported here. Additionally, the spectra of the precursor sodium beta -alumina as well as the europium and samarium trichloride starting materials are presented.

  5. First-principles study of hydrogen diffusion in α-Al2O3 and liquid alumina

    NASA Astrophysics Data System (ADS)

    Belonoshko, A. B.; Rosengren, A.; Dong, Q.; Hultquist, G.; Leygraf, C.

    2004-01-01

    We have studied the energetics and mobility of neutral hydrogen in alumina Al2O3 using ab initio density-functional calculations. The mobility of hydrogen was studied in corundum (α-Al2O3) as well as in liquid alumina. Using both static as well as molecular-dynamics calculations, and applying classical transition state theory, we derive the temperature-dependent diffusivity of hydrogen in α-Al2O3 as D(T)=(21.7×10-8 m2/s)exp(-1.24 eV/kT). The corresponding diffusivity of hydrogen in liquid/amorphous alumina, derived directly from ab initio molecular dynamics calculations, is D(T)=(8.71×10-7 m2/s)exp(-0.91 eV/kT). The computed diffusivity compares very well to experimental data. We conclude that diffusion of neutral hydrogen through the bulk of alumina is a good approximation of the mechanism for hydrogen mobility in corrosion scales. The representation of grain-boundary structures by amorphous alumina is, probably, realistic at higher temperatures.

  6. The effect of different powder particle size on mechanical properties of sintered alumina, resin- and glass-infused alumina.

    PubMed

    Chaiyabutr, Yada; Giordano, Russell; Pober, Richard

    2009-02-01

    In this study, the compaction and sintering behavior of fine alumina powders of different particle sizes and the effect of matrix particle size on biaxial strength and fracture toughness of infused matrices were investigated. Three different alumina powders, In-Ceram alumina, A16SG, and RC172 were selected, representing a range of particle size and shape. RC172 and A16SG were dry-pressed. In-Ceram alumina was slip-cast following manufacturer's recommendations. Dry-pressed ceramic blocks were sectioned into disks with a thickness of 1.5-mm. Uninfused disks were sintered at four temperatures between 1250 degrees C and 1400 degrees C. For glass or resin infused specimens, alumina disks were sintered at 1250 degrees C for 2 h and separated into two groups for glass infusion and resin (UDMA/TEGDMA) infusion. Disks were tested for biaxial flexural strength with a universal testing machine (Instron) at 0.5-mm/min crosshead speeds. One-way ANOVA and Duncan's multiple range tests revealed that alumina disks with different smaller particle sizes have significantly higher biaxial strength (p < 0.05). The strength of the alumina matrix was greatly increased by glass and resin infusion. The biaxial strength of resin-infused alumina increased as particle size decreased, whereas strength of glass-infused alumina was constant.

  7. Damping Behavior of Alumina Epoxy Nano-Composites

    NASA Astrophysics Data System (ADS)

    Katiyar, Priyanka; Kumar, Anand

    2016-10-01

    Polymer nano composites, consisting of a polymer matrix with nanoparticle filler, have been predicted to be one of the most beneficial applications of nanotechnology. Addition of nano particulates to a polymer matrix enhances its performance by capitalizing on the nature and properties of the nano-scale fillers. The damping behavior of composites with nano structured phases is significantly different from that of micro structured materials. Viscoelastic homopolymer exhibit a high material damping response over a relatively narrow range of temperature and frequencies. In many practical situations, a polymeric structure is required to possess better strength and stiffness properties together with a reasonable damping behavior. Viscoelastic polymers show higher loss factor beyond the glassy region which comes with a significant drop in the specific modulus. Addition of nano alumina particles to epoxy leads to improved strength and stiffness properties with an increase in glass transition temperature while retaining its damping capability. Experimental investigations are carried out on composite beam specimen fabricated with different compositions of alumina nano particles in epoxy to evaluate loss factor, tan δ. Impact damping method is used for time response analysis. A single point Laser is used to record the transverse displacement of a point on the composite beam specimen. The experimental results are compared with theoretical estimation of loss factor using Voigt estimation. The effect of inter phase is included in theoretical estimation of loss factor. The result reveals that the study of interface properties is very important in deriving the overall loss factor of the composite since interface occupies a significant volume fraction in the composite.

  8. Suboptimal inhaler medication adherence and incorrect technique are common among chronic obstructive pulmonary disease patients.

    PubMed

    Sriram, Krishna B; Percival, Matthew

    2016-02-01

    Patients with chronic obstructive pulmonary disease (COPD) are routinely prescribed one or more inhaled medications. Adherence to inhaler medications and correct inhaler device technique are crucial to successful COPD management. The goals of this study were to estimate adherence and inhaler technique in a cohort of COPD patients. This was an observational study conducted on a sample of 150 COPD patients. Medication adherence was assessed using the Medication Adherence Report Scale (MARS). Inhaler technique was assessed using standardized checklists. Clinical data were collected using a proforma. Of the 150 patients (mean age 70.3 years, 52% male), 58% reported suboptimal adherence (MARS ≤ 24). High adherence to therapy (MARS = 25) was associated with older age (p = 0.001), but not any of the other studied variables. Medication non-adherence was not associated with COPD exacerbations. Errors (≥ 1) in inhaler technique were common across all of the types of inhaler devices reportedly used by patients, with the highest proportion of errors among Turbuhaler users (83%) and the least proportion of errors among Handihaler users (50%). No clinical variables were associated with errors in inhaler technique. Suboptimal adherence and errors in inhaler technique are common among COPD patients. No clinical variables to assist in the prediction of medication non-adherence and poor inhaler technique were identifiable. Consequently, regular assessment of medication adherence and inhaler technique should be incorporated into routine clinical practice to facilitate improved health outcomes among patients with COPD.

  9. ADHERENCE AND QUALITY OF LIFE IN PATIENTS WITH TYPE II DIABETES MELLITUS IN NORTHERN GREECE

    PubMed Central

    Zioga, Efrosini; Kazakos, Kyriakos; Dimopoulos, Evagelos; Koutras, Christos; Marmara, Kalliopi; Marmara, Eleni-Efrosini; Marmaras, Athanasios; Lavdaniti, Maria

    2016-01-01

    Introduction: Adherence as a concept includes various types of health-related behavior. Better medical adherence leads to improved disease control and fewer diabetes–related complications. Quality of life and medication adherence are interrelated. Patients with diabetes who adhere to their treatment can experience an improvement in quality of life and vice versa. Aim: To assess treatment adherence in patients with type II diabetes, as well as the connection between adherence and quality of life. Methodology: A descriptive non-experimental study was conducted in a provincial hospital in Northern Greece. The sample examined was a convenience sample consisting of 108 patients with type II diabetes mellitus. They completed the “Diabetes Self-Care Activities Questionnaire” and SF-36 “Quality of Life Questionnaire”. Results: Participants demonstrated good adherence to diet and blood test / blood glucose test routines, but did not experience high levels of quality of life. The type of treatment affected the adherence to blood tests with a statistically significant difference (p=0,000). Also, marital status affected mental health with a statistically significant difference (p=0,032). The adherence sub scales are correlated with the all domains of quality of life. Conclusions: According to our findings, it is important to plan interventions to enhance adherence to other types of treatment and to help patients to further improve their quality of life. PMID:27698597

  10. Therapist Adherence to Good Psychiatric Practice in a Short-Term Treatment for Borderline Personality Disorder.

    PubMed

    Kolly, Stéphane; Despland, Jean-Nicolas; de Roten, Yves; Marquet, Pierre; Kramer, Ueli

    2016-07-01

    Therapist adherence describes the quality of interventions according to the imperatives of a treatment model. We examined the relationship between therapist adherence and symptom change in the context of a short-term treatment with respect good psychiatric management (GPM) principles. Based on a parent trial, borderline personality disorder patients (N = 40) benefited from a 10-session intervention. Adherence to GPM was assessed using a GPM Adherence Scale (GPMAS). The psychometric properties of the GPMAS were excellent, and the adherence to GPM explained 16% of the general symptom improvement (t(1) = 2.38, β = 0.40, p = 0.02) and 23% of the borderline symptom improvement (t(1) = 2.46, β = 0.48, p = 0.02). Because GPM adherence predicts the outcome after only 10 sessions, GPMAS is a valuable measure early on in psychiatric practice as part of an initial step to longer-term treatment, to quickly detect problems and correct them.

  11. Segregation phenomena at growing alumina/alloy interfaces

    SciTech Connect

    Hou, Peggy Y.

    2005-03-30

    The chemistry and structure at the scale/alloy interface are important factors governing scale adhesion. The chemical changes can occur from segregation of impurities in the alloy, such as sulphur and carbon, or alloying elements such as chromium, aluminium and reactive elements. This paper reviews studies of the changes of interfacial composition with oxidation time for Al{sub 2}O{sub 3} formed on several model alumina-forming alloys, and tries to relate that to the interfacial strength. Results show that sulphur segregation to oxide/metal interfaces can indeed occur, but the type and amount of segregants at the interface depend on the alloy composition and the interface structure. Co-segregation of impurities with alloying elements can also occur, resulting in multi-layer segregants at the interface. Sulphur-containing interfaces are indeed weaker, but the major role of sulphur is to enhance interfacial void formation. Reactive elements in the alloy not only gather sulfur but also exert an additional positive effect on scale adhesion.

  12. Current Concepts for PrEP Adherence

    PubMed Central

    Haberer, Jessica E.

    2016-01-01

    Purpose of review This review describes 1) the current understanding of adherence to oral PrEP, 2) methods for adherence measurement, 3) approaches to supporting PrEP adherence, and 4) guidance for defining PrEP adherence goals within the larger context of HIV prevention. Recent findings PrEP adherence has generally been higher in recent trials, open-label extensions, and demonstration projects compared to the initial clinical trials; potential explanations include known PrEP efficacy and different motivations to take PrEP. Recent studies have explored adherence monitoring through electronic pill containers, short message service (SMS), and drug concentrations in hair and dried blood spots. The few PrEP adherence interventions developed to date include combinations of enhanced counseling, feedback of objective adherence measurement, and SMS. Conceptualization of PrEP adherence is evolving. The goal is not 100% adherence indefinitely, as it was in clinical trials. PrEP adherence should be defined with respect to HIV exposure, which varies over time by sexual behavior and use of other prevention strategies. Summary PrEP adherence beyond clinical trials has generally been high enough to achieve reliable HIV prevention. Future efforts to measure and support PrEP adherence should focus on the context of risk for HIV acquisition, accounting for dynamic behaviors and choices among HIV prevention options. PMID:26633638

  13. Improved Synthesis Of Potassium Beta' '-Alumina

    NASA Technical Reports Server (NTRS)

    Williams, Roger M.; Jeffries-Nakamura, Barbara; Ryan, Margaret A.; O'Connor, Dennis E.; Kisor, Adam; Underwood, Mark

    1996-01-01

    Improved formulations of precursor materials synthesize nearly-phase-pure potassium beta' '-alumina solid electrolyte (K-BASE) powder. Materials are microhomogeneous powders (or, alternatively, gels) containing K(+,) Mg(2+), and Al(3+). K-BASE powder produced used in potassium-working-fluid alkali-metal thermal-to-electric conversion (K-AMTEC), in which heat-input and heat-rejection temperatures lower than sodium-working-fluid AMTEC (Na-AMTEC). Additional potential use lies in purification of pottassium by removal of sodium and calcium.

  14. On the inelastic shock profile in alumina

    NASA Astrophysics Data System (ADS)

    Marom, H.; Sherman, D.; Rosenberg, Z.; Murray, N.

    2002-11-01

    The dynamic response of alumina specimens, above their elastic limits, was studied using planar impact experiments with different tile thickness. Stress-time measurements with manganin gauges show a steady spreading of the inelastic portion of the shock profile with increasing tile thickness. Such behavior is typical of elastic waves moving at a constant speed that depends on their amplitude. This finding supports recent interpretations of the failure ramp, by which the elastic response of these materials should be extended to higher stresses than the initial jump. However, further analysis of these profiles raises some questions regarding the exact determination of the Hugoniot elastic limit.

  15. Anisotropic shrinkage characteristics of tape cast alumina

    NASA Astrophysics Data System (ADS)

    Patwardhan, Jaideep Suresh

    Dimensional control during sintering is a major issue in ceramics processing to avoid high post-sintering costs associated with machining of the fired ceramic part to desired tolerances and dimensions. Ceramic forming processes such as tape casting, injection molding, and extrusion involve shear of anisotropic particles resulting in preferential alignment of the particles in the green body. This preferential alignment causes directionality in mechanical, electrical, optical, and magnetic properties and most importantly warpage or distortion during sintering. A large effort has been devoted to synthesizing ceramic green bodies with minimal density gradients and uniform packing and modeling the sintering behavior evolution but little effort has been devoted to characterizing orientation of particles and the effect of preferential alignment on sintering shrinkage anisotropy. A systematic study was initiated to study the effect of processing variables such as shear rate, solids loading, temperature, and binder content on aqueous tape cast alumina. Three different alumina systems: A16-SG, Baikowski RC-UFX DBM and RC-LS DBM were investigated. Aqueous tapes of high solids loading alumina (56 vol. %) were tape cast at various speeds and thicknesses and assuming plane Couette flow a shear rate regime of 21--270 s-1 was investigated. Higher shear rates and high solids loading resulted in higher in-plane anisotropy whereas the anisotropy in the thickness direction was higher for low solids loading systems. The anisotropy was found to be fairly constant above a certain critical shear rate (˜100 s-1) irrespective of the temperature and the solids loading and this correlated with the viscosity-shear rate relationship of the cast slips. The higher shrinkage anisotropy in the thickness direction for the low solids loading systems (35 and 45 vol. %) was attributed to the higher amount of organics in the slip required to sustain the suitable viscosity for tape casting and

  16. Intercalation of water into lithium. beta. -alumina

    SciTech Connect

    Dudney, N J; Bates, J B; Wang, J C; Brown, G M; Larson, B C; Engstrom, H

    1981-01-01

    Infrared absorption, neutron diffraction and weight loss techniques have been used to investigate the hydration of single crystals of Li ..beta..-alumina. The hydration is a reversible intercalation reaction. Up to approximately two water molecules per formula unit can penetrate the conduction plane. Other protonated species are formed from the dissociation of the molecular water. The rate of hydration is controlled by the diffusion of water in the conduction plane. A likely diffusion mechanism requires dissociation of the water and an interstitialcy motion of the oxygen.

  17. Quantum dots confined in nanoporous alumina membranes

    NASA Astrophysics Data System (ADS)

    Xu, Jun; Xia, Jianfeng; Wang, Jun; Shinar, Joseph; Lin, Zhiqun

    2006-09-01

    CdSe /ZnS core/shell quantum dots (QDs) were filled into porous alumina membranes (PAMs) by dip coating. The deposition of QDs induced changes in the refractive index of the PAMs. The amount of absorbed QDs was quantified by fitting the reflection and transmission spectra observed experimentally with one side open and freestanding (i.e., with two sides open) PAMs employed, respectively. The fluorescence of the QDs was found to be retained within the cylindrical nanopores of the PAMs.

  18. Conduction mechanism of single-crystal alumina

    NASA Technical Reports Server (NTRS)

    Will, Fritz G.; Delorenzi, Horst G.; Janora, Kevin H.

    1992-01-01

    The fully guarded three-terminal technique was used to perform conductivity measurements on single-crystal alumina at temperatures of 400-1300 C. The conductivity was also determined as a function of time at various temperatures and applied fields. Further, the fractions of the current carried by Al and O ions (ionic transference numbers) were determined from long-term transference experiments in the temperature range 1100-1300 C. A mathematical model of the conduction mechanism is proposed, and model predictions are compared with experimental results.

  19. Association between adherence, treatment satisfaction and illness perception in hypertensive patients.

    PubMed

    Saarti, S; Hajj, A; Karam, L; Jabbour, H; Sarkis, A; El Osta, N; Rabbaa Khabbaz, L

    2016-05-01

    The relationship between adherence to antihypertension medications, treatment satisfaction and illness perception has not been studied so far. The primary objective of this study was to examine the association between adherence to medication, treatment satisfaction and illness perception in Lebanese hypertensive patients. The relation between medication adherence and blood pressure (BP) control was also assessed. In this cross-sectional study, patients were recruited from the physician's practice offices and community pharmacies in Beirut. Patients who had been treated for hypertension for at least 3 months were invited to participate in the study; they completed three questionnaires: the 8-item Morisky Medication Adherence Scale (MMAS-8), the Treatment Satisfaction Questionnaire for Medication (TSQM-4) and the Brief Illness Perception Questionnaire (BIPQ). BP was also measured and recorded. A total of 117 subjects were included, of whom 29.1% had poor adherence to their antihypertension treatment (MMAS-8 scores<6). The odds of having well-controlled hypertension was 3.5 times higher in patients with high adherence compared with patients with poor adherence (P=0.010). Treatment satisfaction was significantly greater in patients with good adherence (P<0.001). Neither socio-demographic, disease- nor drug-related characteristics of the participants were significantly associated with medication adherence. As for illness perception, even though the mean BIPQ score of adherent participants was lower than the mean score of non-adherent participants, this difference did not reach statistical significance. In conclusion, treatment satisfaction was found to be a predictor of adherence. Studies are needed to determine whether interventions to increase satisfaction can improve adherence and BP control.

  20. Issues in nanocomposite ceramic engineering: focus on processing and properties of alumina-based composites.

    PubMed

    Palmero, Paola; Kern, Frank; Sommer, Frank; Lombardi, Mariangela; Gadow, Rainer; Montanaro, Laura

    2014-12-30

    Ceramic nanocomposites, containing at least one phase in the nanometric dimension, have received special interest in recent years. They have, in fact, demonstrated increased performance, reliability and lifetime with respect to monolithic ceramics. However, a successful approach to the production of tailored composite nanostructures requires the development of innovative concepts at each step of manufacturing, from the synthesis of composite nanopowders, to their processing and sintering.This review aims to deepen understanding of some of the critical issues associated with the manufacturing of nanocomposite ceramics, focusing on alumina-based composite systems. Two case studies are presented and briefly discussed. The former illustrates the benefits, in terms of sintered microstructure and related mechanical properties, resulting from the application of an engineering approach to a laboratory-scale protocol for the elaboration of nanocomposites in the system alumina-ZrO2-YAG (yttrium aluminium garnet). The latter illustrates the manufacturing of alumina-based composites for large-scale applications such as cutting tools, carried out by an injection molding process. The need for an engineering approach to be applied in all processing steps is demonstrated also in this second case study, where a tailored manufacturing process is required to obtain the desired results.

  1. Microstructural and Mechanical Characterization of Actively Brazed Alumina Specimens

    SciTech Connect

    Hosking, F.M.; Cadden, C.H.; Stephens, J.J.; Glass, S.J.; Yang, N.Y.C.; Vianco, P.V.; Walker, C.A.

    1999-08-26

    Alumina (94 and 99.8% grade compositions) was brazed directly to itself with gold-based active brazing alloys (ABA's) containing vanadium additions of 1,2 and 3 weight percent. The effects of brazing conditions on the joint properties were investigated. Wetting behavior, interfacial reactions, microstructure, hermeticity and tensile strength were determined. Wetting was fair to good for the ABA and base material combinations. Microanalysis identified a discontinuous Al-V-O spinel reaction product at the alumina-braze interface. Tensile strength results for 94% alumina were uniformly good and generally not sensitive to the vanadium concentration, with tensile values of 85-105 MPa. There was more variability in the 99.8% alumina strength results, with values ranging from 25-95 MPa. The highest vanadium concentration (3 wt. %) yielded the highest joint strength for the brazed 99.8% alumina. Failures in the 99.8% alumina samples occurred at the braze-alumina interface, while the 94% alumina specimens exhibited fracture of the ceramic substrate.

  2. Dynamic compressive and tensile strengths of spark plasma sintered alumina

    SciTech Connect

    Girlitsky, I.; Zaretsky, E.; Kalabukhov, S.; Dariel, M. P.; Frage, N.

    2014-06-28

    Fully dense submicron grain size alumina samples were manufactured from alumina nano-powder using Spark Plasma Sintering and tested in two kinds of VISAR-instrumented planar impact tests. In the first kind, samples were loaded by 1-mm tungsten impactors, accelerated to a velocity of about 1 km/s. These tests were aimed at studying the Hugoniot elastic limit (HEL) of Spark Plasma Sintering (SPS)-processed alumina and the decay, with propagation distance, of the elastic precursor wave. In the tests of the second kind, alumina samples of 3-mm thickness were loaded by 1-mm copper impactors accelerated to 100–1000 m/s. These tests were aimed at studying the dynamic tensile (spall) strength of the alumina specimens. The tensile fracture of the un-alloyed alumina shows a monotonic decline of the spall strength with the amplitude of the loading stress pulse. Analysis of the decay of the elastic precursor wave allowed determining the rate of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced inelastic deformation and to clarify the mechanisms responsible for the deformation. The 1-% addition of Cr{sub 2}O{sub 3} decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.

  3. Process for the recovery of alumina from fly ash

    DOEpatents

    Murtha, M.J.

    1983-08-09

    An improvement in the lime-sinter process for recovering alumina from pulverized coal fly ash is disclosed. The addition of from 2 to 10 weight percent carbon and sulfur to the fly ash-calcium carbonate mixture increase alumina recovery at lower sintering temperatures.

  4. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... nanoparticles (generic). 721.10120 Section 721.10120 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical... as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this...

  5. Dynamic compressive and tensile strengths of spark plasma sintered alumina

    NASA Astrophysics Data System (ADS)

    Girlitsky, I.; Zaretsky, E.; Kalabukhov, S.; Dariel, M. P.; Frage, N.

    2014-06-01

    Fully dense submicron grain size alumina samples were manufactured from alumina nano-powder using Spark Plasma Sintering and tested in two kinds of VISAR-instrumented planar impact tests. In the first kind, samples were loaded by 1-mm tungsten impactors, accelerated to a velocity of about 1 km/s. These tests were aimed at studying the Hugoniot elastic limit (HEL) of Spark Plasma Sintering (SPS)-processed alumina and the decay, with propagation distance, of the elastic precursor wave. In the tests of the second kind, alumina samples of 3-mm thickness were loaded by 1-mm copper impactors accelerated to 100-1000 m/s. These tests were aimed at studying the dynamic tensile (spall) strength of the alumina specimens. The tensile fracture of the un-alloyed alumina shows a monotonic decline of the spall strength with the amplitude of the loading stress pulse. Analysis of the decay of the elastic precursor wave allowed determining the rate of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced inelastic deformation and to clarify the mechanisms responsible for the deformation. The 1-% addition of Cr2O3 decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.

  6. Treatment of chrome plating wastewater (Cr+6) using activated alumina.

    PubMed

    Sarkar, Sudipta; Gupta, Anirban

    2003-01-01

    Suitability of activated alumina for removal of hexavalent chromium from electroplating wastewater has been investigated. Activated alumina exhibited good sorption capacity for hexavalent chromium and pH has no pronounced effect on the sorption capacity. Both batch and column adsorption studies have been carried out and an adsorption column design indicated reasonable depth of column for practical application.

  7. Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ

    PubMed Central

    Firlar, Emre; Çınar, Simge; Kashyap, Sanjay; Akinc, Mufit; Prozorov, Tanya

    2015-01-01

    Rheological behavior of aqueous suspensions containing nanometer-sized powders is of relevance to many branches of industry. Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models. Formation of so-called hydration layer on alumina nanoparticles in water was hypothesized, but never observed experimentally. We report here on the direct visualization of aqueous suspensions of alumina with the fluid cell in situ. We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions. We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions. Our findings elucidate the source of high viscosity observed for nanoparticle suspensions and are of direct relevance to many industrial sectors including materials, food, cosmetics, pharmaceutical among others employing colloidal slurries with nanometer-scale particles. PMID:25996055

  8. Decisional capacity and medication adherence among youth with HIV.

    PubMed

    Chenneville, Tiffany; Clutter, Michiko Otsuki; Hintz, Stephanie; Walsh, Audra; Emmanuel, Patricia; Lujan-Zilberman, Jorge; Rodriguez, Carina

    2015-01-01

    This exploratory study examined the degree to which decisional capacity (DC) is associated with measures of self-reported medication adherence. We hypothesized that youth with higher levels of DC would report greater levels of antiretroviral medication adherence. Seventy-two (72) youth with HIV aged 13-24 participated in this study. Data collection included administration of the MacArthur Competence Tool for Treatment and measures of adherence (i.e., seven-day self-report interview, visual analog scale, and biological indicators). Data were analyzed using descriptive statistics, intercorrelations, and multiple and Poisson regression analyses. Youth with HIV who exhibited greater understanding of their disease were more likely to report fewer missed doses in the last seven days. Findings build upon literature in the areas of DC and health literacy and highlight the potential utility of enhancing HIV disease understanding among youth with HIV.

  9. Experimental study of 248nm excimer laser etching of alumina

    NASA Astrophysics Data System (ADS)

    Hu, Hongtao; Shao, Jingzhen; Wang, Xi; Fang, Xiaodong

    2016-10-01

    The 248 nm excimer laser etching characteristic of alumina ceramic and sapphire had been studied using different laser fluence and different number of pulses. And the interaction mechanism of 248 nm excimer laser with alumina ceramic and sapphire had been analyzed. The results showed that when the laser fluence was less than 8 J/cm2, the etching depth of alumina ceramic and sapphire were increased with the increase of laser fluence and number of pulses. At the high number pulses and high-energy, the surface of the sapphire had no obvious melting phenomenon, and the alumina ceramic appeared obvious melting phenomenon. The interaction mechanism of excimer laser with alumina ceramics and sapphire was mainly two-photon absorption. But because of the existence of impurities and defects, the coupling between the laser radiation and ceramic and sapphire was strong, and the thermal evaporation mechanism was also obvious.

  10. Thermal Conductivity of Alumina-reinforced Zirconia Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    2005-01-01

    10-mol% yttria-stabilized zirconia (10SZ) - alumina composites containing 0-30 mol% alumina were fabricated by hot pressing at 1500 C in vacuum. Thermal conductivity was determined at various temperatures using a steady-state laser heat flux technique. Thermal conductivity of the composites increased with increase in alumina content. Composites containing 0, 5, and 10-mol% alumina did not show any change in thermal conductivity with temperature. However, those containing 20 and 30-mol% alumina showed a decrease in thermal conductivity with increase in temperature. The measured values of thermal conductivity were in good agreement with those calculated from the Maxwell-Eucken model where one phase is uniformly dispersed within a second major continuous phase.

  11. Adherence issues related to sublingual immunotherapy as perceived by allergists

    PubMed Central

    Scurati, Silvia; Frati, Franco; Passalacqua, Gianni; Puccinelli, Paola; Hilaire, Cecile; Incorvaia, Cristoforo

    2010-01-01

    Objectives: Sublingual immunotherapy (SLIT) is a viable alternative to subcutaneous immunotherapy to treat allergic rhinitis and asthma, and is widely used in clinical practice in many European countries. The clinical efficacy of SLIT has been established in a number of clinical trials and meta-analyses. However, because SLIT is self-administered by patients without medical supervision, the degree of patient adherence with treatment is still a concern. The objective of this study was to evaluate the perception by allergists of issues related to SLIT adherence. Methods: We performed a questionnaire-based survey of 296 Italian allergists, based on the adherence issues known from previous studies. The perception of importance of each item was assessed by a VAS scale ranging from 0 to 10. Results: Patient perception of clinical efficacy was considered the most important factor (ranked 1 by 54% of allergists), followed by the possibility of reimbursement (ranked 1 by 34%), and by the absence of side effects (ranked 1 by 21%). Patient education, regular follow-up, and ease of use of SLIT were ranked first by less than 20% of allergists. Conclusion: These findings indicate that clinical efficacy, cost, and side effects are perceived as the major issues influencing patient adherence to SLIT, and that further improvement of adherence is likely to be achieved by improving the patient information provided by prescribers. PMID:20622914

  12. Adsorption of carboxymethyl cellulose on alumina particles.

    PubMed

    Zhivkov, Alexandar M; Hristov, Rosen P

    2015-06-01

    The polyelectrolyte adsorption on colloid particles is often used for stabilization or flocculation of water suspensions. The aim of this work is to study the adsorption of carboxymethyl cellulose (CMC) on alumina (γ-Al2O3) colloid particles. The particles and polymer are chosen because of the capability of the metal-oxide ampholyte surface and the weak polyelectrolytes to alter their charge by pH. The measurements are done at pH 6.0 where the CMC carboxylic gropes are almost fully dissociated and the alumina surface is positively charged. The high linear charge density of the polyelectrolyte chain provides Na(+) counterions condensation on the COO(-) groups. The main employed method is the electric light scattering based on particle orientation in sinusoidal electric field. The electric polarizability and the relaxation time after field switching off (both depending on the particle charge and size) are used as criteria for polymer adsorption and particle aggregation. Micro-electrophoresis is applied as additional techniques indicating the sign and density of the surface charge. The results obtained give the conditions (time dependence, particle and polymer concentrations) where the CMC adsorption is complete and the suspension is stable.

  13. Combination for electrolytic reduction of alumina

    DOEpatents

    Brown, Craig W.; Brooks, Richard J.; Frizzle, Patrick B.; Juric, Drago D.

    2002-04-30

    An electrolytic bath for use during the electrolytic reduction of alumina to aluminum. The bath comprises molten electrolyte having the following ingredients: AlF.sub.3 and at least one salt selected from the group consisting of NaF, KF, and LiF; and about 0.004 wt. % to about 0.2 wt. %, based on total weight of the molten electrolyte, of at least one transition metal or at least one compound of the metal or both. The compound is, a fluoride; oxide, or carbonate. The metal is nickel, iron, copper, cobalt, or molybdenum. The bath is employed in a combination including a vessel for containing the bath and at least one non-consumable anode and at least one dimensionally stable cathode in the bath. Employing the instant bath during electrolytic reduction of alumina to aluminum improves the wetting of aluminum on a cathode by reducing or eliminating the formation of non-metallic deposits on the cathode.

  14. Properties of Transition Metal Doped Alumina

    NASA Astrophysics Data System (ADS)

    Nykwest, Erik; Limmer, Krista; Brennan, Ray; Blair, Victoria; Ramprasad, Rampi

    Crystallographic texture can have profound effects on the properties of a material. One method of texturing is through the application of an external magnetic field during processing. While this method works with highly magnetic systems, doping is required to couple non-magnetic systems with the external field. Experiments have shown that low concentrations of rare earth (RE) dopants in alumina powders have enabled this kind of texturing. The magnetic properties of RE elements are directly related to their f orbital, which can have as many as 7 unpaired electrons. Since d-block elements can have as many as 5 unpaired electrons the effects of substitutional doping of 3d transition metals (TM) for Al in alpha (stable) and theta (metastable) alumina on the local structure and magnetic properties, in addition to the energetic cost, have been calculated by performing first-principles calculations based on density functional theory. This study has led to the development of general guidelines for the magnetic moment distribution at and around the dopant atom, and the dependence of this distribution on the dopant atom type and its coordination environment. It is anticipated that these findings can aid in the selection of suitable dopants help to guide parallel experimental efforts. This project was supported in part by an internship at the Army Research Laboratory, administered by the Oak Ridge Institute for Science and Education, along with a grant of computer time from the DoD High Performance Computing Modernization Program.

  15. Enhancing Adherence in Clinical Exercise Trials.

    ERIC Educational Resources Information Center

    O'Neal, Heather A.; Blair, Steven N.

    2001-01-01

    Discusses exercise adherence from the perspective of adhering to an exercise treatment in a controlled trial, focusing on: adherence (to intervention and measurement); the development of randomized clinical trials; exemplary randomized clinical trials in exercise science (exercise training studies and physical activity interventions); and study…

  16. Parsing abnormal grain growth in specialty aluminas

    NASA Astrophysics Data System (ADS)

    Lawrence, Abigail Kremer

    Grain growth in alumina is strongly affected by the impurities present in the material. Certain impurity elements are known to have characteristic effects on abnormal grain growth in alumina. Specialty alumina powders contain multiple impurity species including MgO, CaO, SiO2, and Na 2O. In this work, sintered samples made from alumina powders containing various amounts of the impurities in question were characterized by their grain size and aspect ratio distributions. Multiple quantitative methods were used to characterize and classify samples with varying microstructures. The grain size distributions were used to partition the grain size population into subpopulations depending on the observed deviation from normal behavior. Using both grain size and aspect ratio a new visual representation for a microstructure was introduced called a morphology frequency map that gives a fingerprint for the material. The number of subpopulations within a sample and the shape of the distribution on the morphology map provided the basis for a classification scheme for different types of microstructures. Also using the two parameters a series of five metrics were calculated that describe the character of the abnormal grains in the sample, these were called abnormal character values. The abnormal character values describe the fraction of grains that are considered abnormal, the average magnitude of abnormality (including both grain size and aspect ratio), the average size, and variance in size. The final metric is the correlation between grain size and aspect ratio for the entire population of grains. The abnormal character values give a sense of how different from "normal" the sample is, given the assumption that a normal sample has a lognormal distribution of grain size and a Gaussian distribution of aspect ratios. In the second part of the work the quantified measures of abnormality were correlated with processing parameters such as composition and heat treatment conditions. A

  17. Final report on the application of chaos theory to an alumina sensor for aluminum reduction cells

    SciTech Connect

    Williford, R.E.; Windisch, C.F. Jr.

    1992-03-01

    Four chaos-related digital signal analysis (DSA) methods were applied to the analysis of voltage and current signals collected from aluminum electrolysis cells. Two separate data bases were analyzed: bench-scale laboratory experiments and a pilot-scale test. The objective was to assess the feasibility of using these types of data and analysis methods as the basis for a non-intrusive sensor to measure the alumina content in the electrolysis bath. This was the first time chaos theory approaches have been employed to analyze aluminum electrolysis cells.

  18. Cryopreservation of adherent neuronal networks.

    PubMed

    Ma, Wu; O'Shaughnessy, Thomas; Chang, Eddie

    2006-07-31

    Neuronal networks have been widely used for neurophysiology, drug discovery and toxicity testing. An essential prerequisite for future widespread application of neuronal networks is the development of efficient cryopreservation protocols to facilitate their storage and transportation. Here is the first report on cryopreservation of mammalian adherent neuronal networks. Dissociated spinal cord cells were attached to a poly-d-lysine/laminin surface and allowed to form neuronal networks. Adherent neuronal networks were embedded in a thin film of collagen gel and loaded with trehalose prior to transfer to a freezing medium containing DMSO, FBS and culture medium. This was followed by a slow rate of cooling to -80 degrees C for 24 h and then storage for up to 2 months in liquid nitrogen at -196 degrees C. The three components: DMSO, collagen gel entrapment and trehalose loading combined provided the highest post-thaw viability, relative to individual or two component protocols. The post-thaw cells with this protocol demonstrated similar neuronal and astrocytic markers and morphological structure as those detected in unfrozen cells. Fluorescent dye FM1-43 staining revealed active recycling of synaptic vesicles upon depolarizing stimulation in the post-thaw neuronal networks. These results suggest that a combination of DMSO, collagen gel entrapment and trehalose loading can significantly improve conventional slow-cooling methods in cryopreservation of adherent neuronal networks.

  19. An observational study of health literacy and medication adherence in adult kidney transplant recipients

    PubMed Central

    Demian, Maryam N.; Shapiro, R. Jean

    2016-01-01

    Background There is a high prevalence of non-adherence to immunosuppressants in kidney transplant recipients. Although limited health literacy is common in kidney recipients and is linked to adverse outcomes in other medical populations, its effect on medication adherence in kidney transplant recipients remains poorly understood. The objective was to investigate the effect of lower health literacy on immunosuppressant adherence. Methods Kidney recipients who were at least 6 months post-transplant and outpatients of Vancouver General Hospital in B.C., Canada were recruited through invitation letters. A total of 96 recipients completed the Health Literacy Questionnaire, which provides a multifactorial profile of self-reported health literacy and the Transplant Effects Questionnaire-Adherence subscale measuring self-reported immunosuppressant adherence. Hierarchical linear regression was used to analyze the association between health literacy and adherence after controlling for identified risk factors of non-adherence. Results Our sample was on average 53 years old, 56% male and 9 years post-transplant. Kidney recipients reported low levels of health literacy on scales measuring active health management and critical appraisal of information and 75% reported non-perfect adherence. Worse adherence was associated with poorer overall health literacy (ΔR2 = 0.08, P = 0.004) and lower scores on six of nine of the health literacy factors. Conclusions Poorer health literacy is associated with lower immunosuppressant adherence in adult kidney transplant recipients suggesting the importance of considering a recipient's level of health literacy in research and clinical contexts. Medication adherence interventions can target the six factors of health literacy identified as being risk factors for lower medication adherence. PMID:27994867

  20. Chronic Obstructive Pulmonary Disease Illness and Medication Beliefs are Associated with Medication Adherence.

    PubMed

    Krauskopf, Katherine; Federman, Alex D; Kale, Minal S; Sigel, Keith M; Martynenko, Melissa; O'Conor, Rachel; Wolf, Michael S; Leventhal, Howard; Wisnivesky, Juan P

    2015-04-01

    Almost half of patients with COPD do not adhere to their medications. Illness and medication beliefs are important determinants of adherence in other chronic diseases. Using the framework of the Common Sense Model of Self-Regulation (CSM), we determined associations between potentially modifiable beliefs and adherence to COPD medications in a cohort of English- and Spanish-speaking adults with COPD from New York and Chicago. Medication adherence was assessed using the Medication Adherence Report Scale. Illness and medication beliefs along CSM domains were evaluated using the Brief Illness Perception Questionnaire (B-IPQ) and the Beliefs about Medications Questionnaire (BMQ). Unadjusted analysis (with Cohen's d effect sizes) and multiple logistic regression were used to assess the relationship between illness and medication beliefs with adherence. The study included 188 participants (47% Black, 13% Hispanics); 109 (58%) were non-adherent. Non-adherent participants were younger (p < 0.001), more likely to be Black or Hispanic (p = 0.001), to have reported low income (p = 0.02), and had fewer years of formal education (p = 0.002). In unadjusted comparisons, non-adherent participants reported being more concerned about their COPD (p = 0.011; Cohen's d = 0.43), more emotionally affected by the disease (p = 0.001; Cohen's d = 0.54), and had greater concerns about COPD medications (p < 0.001, Cohen's d = 0.81). In adjusted analyses, concerns about COPD medications independently predicted non-adherence (odds ratio: 0.52, 95% confidence interval: 0.36-0.75). In this cohort of urban minority adults, concerns about medications were associated with non-adherence. Future work should explore interventions to influence patient adherence by addressing concerns about the safety profile and long-term effects of COPD medications.

  1. Scales

    ScienceCinema

    Murray Gibson

    2016-07-12

    Musical scales involve notes that, sounded simultaneously (chords), sound good together. The result is the left brain meeting the right brain — a Pythagorean interval of overlapping notes. This synergy would suggest less difference between the working of the right brain and the left brain than common wisdom would dictate. The pleasing sound of harmony comes when two notes share a common harmonic, meaning that their frequencies are in simple integer ratios, such as 3/2 (G/C) or 5/4 (E/C).

  2. Scales

    SciTech Connect

    Murray Gibson

    2007-04-27

    Musical scales involve notes that, sounded simultaneously (chords), sound good together. The result is the left brain meeting the right brain — a Pythagorean interval of overlapping notes. This synergy would suggest less difference between the working of the right brain and the left brain than common wisdom would dictate. The pleasing sound of harmony comes when two notes share a common harmonic, meaning that their frequencies are in simple integer ratios, such as 3/2 (G/C) or 5/4 (E/C).

  3. Fabrication of Alumina Nanowires from Porous Alumina Membranes by Etching in Phosphoric Acid Solution

    NASA Astrophysics Data System (ADS)

    Wang, Xuehua; Li, Chengyong; Ma, Lianjiao; Cao, Hong; Zhang, Baohua

    Alumina nanowires (ANWs) with high aspect ratios were synthesized by the chemical etching of porous alumina membranes (PAMs) in phosphoric acid solution. The morphology and structure of ANWs were analyzed by SEM and XRD, respectively. The results showed that the typical features of ANWs are around 35 nm in diameter and around 20 μm in length, the crystalline structure of the ANWs was amorphous, which was in accordance with that of the PAMs. Furthermore, the morphology of the PAMs was characterized by AFM and SEM in detail. On the basis of AFM and SEM observations, a possible formation mechanism of ANWs was discussed, and the inhomogeneous of the dissolution between the triple points and the side walls was considered to be the essential factor deciding the formation of ANWs.

  4. Terbium luminescence in alumina xerogel fabricated in porous anodic alumina matrix under various excitation conditions

    SciTech Connect

    Gaponenko, N. V.; Kortov, V. S.; Orekhovskaya, T. I.; Nikolaenko, I. A.; Pustovarov, V. A.; Zvonarev, S. V.; Slesarev, A. I.; Prislopski, S. Ya.

    2011-07-15

    Terbium-doped alumina xerogel layers are synthesized by the sol-gel method in pores of a porous anodic alumina film 1 {mu}m thick with a pore diameter of 150-180 nm; the film is grown on a silicon substrate. The fabricated structures exhibit terbium photoluminescence with bands typical of trivalent terbium terms. Terbium X-ray luminescence with the most intense band at 542 nm is observed for the first time for such a structure. Morphological analysis of the structure by scanning electron microscopy shows the presence of xerogel clusters in pore channels, while the main pore volume remains unfilled and pore mouths remain open. The data obtained confirm the promising applications of fabricated structures for developing matrix converters of X-rays and other ionizing radiations into visible light. The possibilities of increasing luminescence intensity in the matrix converter are discussed.

  5. Processing and mechanical characterization of alumina laminates

    NASA Astrophysics Data System (ADS)

    Montgomery, John K.

    2002-08-01

    Single-phase ceramics that combine property gradients or steps in monolithic bodies are sought as alternatives to ceramic composites made of dissimilar materials. This work describes novel processing methods to produce stepped-density (or laminated) alumina single-phase bodies that maintain their mechanical integrity. One arrangement consists of a stiff, dense bulk material with a thin, flaw tolerant, porous exterior layer. Another configuration consists of a lightweight, low-density bulk material with a thin, hard, wear resistant exterior layer. Alumina laminates with strong interfaces have been successfully produced in this work using two different direct-casting processes. Gelcasting is a useful near-net shape processing technique that has been combined with several techniques, such as reaction bonding of aluminum oxide and the use of starch as a fugative filler, to successfully produced stepped-density alumina laminates. The other direct casting process that has been developed in this work is thermoreversible gelcasting (TRG). This is a reversible gelation process that has been used to produce near-net shape dense ceramic bodies. Also, individual layers can be stacked together and heated to produce laminates. Bilayer laminate samples were produced with varied thickness of porous and dense layers. It was shown that due to the difference in modulus and hardness, transverse cracking is found upon Hertzian contact when the dense layer is on the exterior. In the opposite arrangement, compacted damage zones formed in the porous material and no damage occurred in the underlying dense layer. Flaw tolerant behavior of the porous exterior/dense underlayer was examined by measuring biaxial strength as a function of Vickers indentation load. It was found that the thinnest layer of porous material results in the greatest flaw tolerance. Also, higher strength was exhibited at large indentation loads when compared to dense monoliths. The calculated stresses on the surfaces

  6. Adherence to cardiovascular medications in the South Asian population: A systematic review of current evidence and future directions

    PubMed Central

    Akeroyd, Julia M; Chan, Winston J; Kamal, Ayeesha K; Palaniappan, Latha; Virani, Salim S

    2015-01-01

    AIM: To review methods of assessing adherence and strategies to improve adherence to cardiovascular disease (CVD) medications, among South Asian CVD patients. METHODS: We conducted a systematic review of English language studies that examined CVD medication adherence in South Asian populations from 1966 to April 1, 2015 in SCOPUS and PubMed. Working in duplicate, we identified 61 studies. After exclusions, 26 studies were selected for full text review. Of these, 17 studies were included in the final review. We abstracted data on several factors including study design, study population, method of assessing adherence and adherence rate. RESULTS: These studies were conducted in India (n = 11), Pakistan (n = 3), Bangladesh (n = 1), Nepal (n = 1) and Sri Lanka (n = 1). Adherence rates ranged from 32%-95% across studies. Of the 17 total publications included, 10 focused on assessing adherence to CVD medications and 7 focused on assessing the impact of interventions on medication adherence. The validated Morisky Medication Adherence Scale (MMAS) was used as the primary method of assessing adherence in five studies. Three studies used validated questionnaires similar to the MMAS, and one study utilized Medication Event Monitoring System caps, with the remainder of the studies utilizing pill count and self-report measures. As expected, studies using non-validated self-report measures described higher rates of adherence than studies using validated scale measurements and pill count. The included intervention studies examined the use of polypill therapy, provider education and patient counseling to improve medication adherence. CONCLUSION: The overall medication adherence rates were low in the region, which suggest a growing need for future interventions to improve adherence. PMID:26730300

  7. Fabrication of alumina films with laminated structures by ac anodization.

    PubMed

    Segawa, Hiroyo; Okano, Hironaga; Wada, Kenji; Inoue, Satoru

    2014-02-01

    Anodization techniques by alternating current (ac) are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50-200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials.

  8. Porous alumina based ordered nanocomposite coating for wear resistance

    NASA Astrophysics Data System (ADS)

    Yadav, Arti; Muthukumar, M.; Bobji, M. S.

    2016-08-01

    Uniformly dispersed nanocomposite coating of aligned metallic nanowires in a matrix of amorphous alumina is fabricated by pulsed electrodeposition of copper into the pores of porous anodic alumina. Uniform deposition is obtained by controlling the geometry of the dendritic structure at the bottom of pores through stepwise voltage reduction followed by mild etching. The tribological behaviour of this nanocomposite coating is evaluated using a ball on flat reciprocating tribometer under the dry contact conditions. The nanocomposite coating has higher wear resistance compared to corresponding porous alumina coating. Wear resistant nanocomposite coating has wide applications especially in protecting the internal surfaces of aluminium internal combustion engines.

  9. Self-diffusion of oxygen in single crystal alumina

    NASA Astrophysics Data System (ADS)

    Oishi, Y.; Ando, Ken; Kubota, Y.

    1980-08-01

    The self-diffusion coefficient of oxygen in (polished slices of a Verneuil) single-crystal alumina was determined in the temperature range 1500-1770 °C by means of the gas-solid isotope exchange technique. The results were represented by D=1.12×103 exp (-155×103/RT) cm2/s. The activation energy was interpreted to be for intrinsic diffusion. By comparison of the results with the oxygen self-diffusion coefficients previously reported for crushed particles of a Verneuil alumina and a vapor-grown alumina, the extrinsic diffusion exhibited by the crushed particles was confirmed to be due to a dislocation enhancement process.

  10. Fabrication of alumina films with laminated structures by ac anodization

    NASA Astrophysics Data System (ADS)

    Segawa, Hiroyo; Okano, Hironaga; Wada, Kenji; Inoue, Satoru

    2014-02-01

    Anodization techniques by alternating current (ac) are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50-200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials.

  11. Processing of silicon nitride and alumina nanosize powders

    SciTech Connect

    Gonzalez, E.J.; Piermarini, G.; Hockey, B.; Malghan, S.G.

    1995-08-01

    The effects of pressure on the compaction and subsequent processing of nanosize {gamma} alumina powders were studied. A 3 mm diameter piston/cylinder die was used to compact the nanosize powders to pressures of 1 and 2.5 GPa. The green bodies were sintered at temperatures up to 1600{degrees}C. Results show that green body density can be increased by higher compaction pressures. It appears that as a result of the {gamma}-to-{alpha} transformation in alumina, higher green density does not necessarily produce a higher density sintered alumina body. The microstructures of the sintered bodies are described in terms of porosity and phase content.

  12. Effects of long term inhalation of alumina fibres in rats.

    PubMed Central

    Pigott, G. H.; Gaskell, B. A.; Ishmael, J.

    1981-01-01

    Groups of rats were exposed by inhalation to atmospheres containing a refractory alumina fibre (Saffil Fibres, I.C.I.) either as manufactured or in a thermally aged form. Similar groups were exposed to UICC chrysotile A asbestos or clean air to serve as positive and negative controls respectively. Exposures continued for 86 weeks after which the animals were maintained to 85% mortality. Pulmonary reaction to both forms of alumina fibre was minimal; chrysotile asbestos provoked the expected progressive fibrosis. Pulmonary tumours (both benign and malignant) were confined to rats dosed with asbestos. The results support the predicted inert nature of these alumina fibres. Images Fig. 2 PMID:7248173

  13. Boria modified alumina probed by methanol dehydration and IR spectroscopy

    NASA Astrophysics Data System (ADS)

    de Farias, Andréa M. Duarte; Esteves, Angela M. Lavogade; Ziarelli, Fabio; Caldarelli, Stefano; Fraga, Marco A.; Appel, Lucia G.

    2004-04-01

    Al 2O 3·B 2O 3 catalysts were synthesized by co-precipitation and impregnation methods applying two calcination temperatures and boria loadings. Catalysts were analyzed by IR spectroscopy of pyridine and CO 2 adsorption and were evaluated in methanol dehydration. Results showed that boron addition to alumina causes a decrease of the number of basic and Lewis acid sites on alumina surface. It could also be observed an enhancement in acid strength of Lewis sites for impregnated samples. The results of methanol dehydration show that strong Brönsted sites are not formed on borate alumina.

  14. Alumina Paste Sublimation Suppression Barrier for Thermoelectric Device

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah (Inventor); Caillat, Thierry (Inventor)

    2014-01-01

    Alumina as a sublimation suppression barrier for a Zintl thermoelectric material in a thermoelectric power generation device operating at high temperature, e.g. at or above 1000K, is disclosed. The Zintl thermoelectric material may comprise Yb.sub.14MnSb.sub.11. The alumina may be applied as an adhesive paste dried and cured on a substantially oxide free surface of the Zintl thermoelectric material and polished to a final thickness. The sublimation suppression barrier may be finalized by baking out the alumina layer on the Zintl thermoelectric material until it becomes substantially clogged with ytterbia.

  15. Preparation ways and photoluminescence of mesoporous alumina

    NASA Astrophysics Data System (ADS)

    Zhang, P.; Liu, J.; Zhao, X.; Wu, G.

    2010-12-01

    High specific surface area (SSA) mesoporous alumina (MA) is synthesized by a sol-gel method using pelagic clay as the raw material. The MA synthesized with a (1-hexadecyl) trimethylammonium bromide (CTAB): utea mixed template shows a SSA of 385.56 m2/g and a mean pore size of 3.6 nm. And the SSA of the MA synthesized with the mixed template is increased compared with the MA synthesized with a CTAB single template. Simultaneously, the MA exhibits a blue photoluminescence which come from the defect F+ and F centers, and the higher PL emission of the MA synthesized with a CTAB: utea mixed template is attributed to the high defect center density in the MA.

  16. Tensile creep behavior of polycrystalline alumina fibers

    NASA Technical Reports Server (NTRS)

    Yun, H. M.; Goldsby, J. C.

    1993-01-01

    Tensile creep studies were conducted on polycrystalline Nextel 610 and Fiber FP alumina fibers with grain sizes of 100 and 300 nm, respectively. Test conditions were temperatures from 800 to 1050 C and stresses from 60 to 1000 MPa. For both fibers, only a small primary creep portion occurred followed by steady-state creep. The stress exponents for steady-state creep of Nextel 610 and Fiber FP were found to be about 3 and 1, respectively. At lower temperatures, below 1000 C, the finer grained Nextel 610 had a much higher 0.2 percent creep strength for 100 hr than the Fiber FP; while at higher temperatures, Nextel 610 had a comparable creep strength to the Fiber FP. The stress and grain size dependencies suggest Nextel 610 and Fiber FP creep rates are due to grain boundary sliding controlled by interface reaction and Nabarro-Herring mechanisms, respectively.

  17. Crystallography of Alumina-YAG-Eutectic

    NASA Technical Reports Server (NTRS)

    Farmer, Serene C.; Sayir, Ali; Dickerson, Robert M.; Matson, Lawrence E.

    2000-01-01

    Multiple descriptions of the alumina-YAG eutectic crystallography appear in the ceramic literature. The orientation between two phases in a eutectic system has direct impact on residual stress, morphology, microstructural stability, and high temperature mechanical properties. A study to demonstrate that the different crystallographic relationships can be correlated with different growth constraints was undertaken. Fibers produced by Laser-Heated Float Zone (LHFZ) and Edge-defined Film-fed Growth (EFG) were examined. A map of the orientation relationship between Al2O3 and Y3Al5O12 and their relationship to the fiber growth axis as a function of pull rate are presented. Regions in which a single orientation predominates are identified.

  18. Optimized alumina coagulants for water treatment

    DOEpatents

    Nyman, May D [Albuquerque, NM; Stewart, Thomas A [Albuquerque, NM

    2012-02-21

    Substitution of a single Ga-atom or single Ge-atom (GaAl.sub.12 and GeAl.sub.12 respectively) into the center of an aluminum Keggin polycation (Al.sub.13) produces an optimal water-treatment product for neutralization and coagulation of anionic contaminants in water. GaAl.sub.12 consistently shows .about.1 order of magnitude increase in pathogen reduction, compared to Al.sub.13. At a concentration of 2 ppm, GaAl.sub.12 performs equivalently to 40 ppm alum, removing .about.90% of the dissolved organic material. The substituted GaAl.sub.12 product also offers extended shelf-life and consistent performance. We also synthesized a related polyaluminum chloride compound made of pre-hydrolyzed dissolved alumina clusters of [GaO.sub.4Al.sub.12(OH).sub.24(H.sub.2O).sub.12].sup.7+.

  19. Electrostatic-based model for alumina surfaces

    NASA Astrophysics Data System (ADS)

    Streitz, F. H.; Mintmire, J. W.

    1994-12-01

    As most technologically important metals will form oxides readily, any complete study of adhesion at real metal surfaces must include the metal-oxide interface. The role of this ubiquitous oxide layer cannot be overlooked, as the adhesive properties of the oxide or oxide-metal system can be expected to differ profoundly from the adhesive properties of a bare metal surface. We report on the development of a novel computational method for molecular dynamics simulations which explicitly includes variable charge transfer between anions and cations. This method is found to be capable of describing the elastic properties, surface energies, and surface relaxation of crystalline metal-oxides accurately. We discuss in detail results using this method of alpha-alumina and several of its low index faces.

  20. Compositional characterization of atomic layer deposited alumina

    SciTech Connect

    Philip, Anu; Thomas, Subin; Kumar, K. Rajeev

    2014-01-28

    As the microelectronic industry demands feature size in the order of few and sub nanometer regime, the film composition and other film properties become critical issues and ALD has emerged as the choice of industry. Aluminum oxide is a material with wide applications in electronic and optoelectronic devices and protective and ion barrier layers. Al{sub 2}O{sub 3} is an excellent dielectric because of its large band gap (8.7eV), large band offsets with silicon. We have deposited thin layers of alumina on silicon wafer (p-type) for gate dielectric applications by ALD technique and compositional characterizations of the deposited thin films were done using EDS, XPS and FTIR spectra.

  1. Microstructure and creep properties of alumina.

    SciTech Connect

    Moreno, J. M. C.; Lopez, A. R.; Rodriguez, A. D.; Routbort, J. L.; Materials Science Division; Univ. of Seville

    1995-01-01

    High temperature creep of two zirconia toughened alumina ceramics, fabricated by powder processing and sol-gel precursors processing, has been studied in order to determine plastic deformation mechanisms. Compressive creep tests were carried out between 1300 and 1450 C, under stresses from 10 to 150 MPa. For the sample fabricated from powders, a stress exponent of 1.4 and an activation energy of 580 kJ/mol were found below a critical stress of 40 MPa. For larger stresses, accelerated creep rates developed. In the specimens processed from precursors, values of 1.8 for the stress exponent and 540 kJ/mol for the activation energy, over the entire range of stresses have been determined. Creep parameters and microstructural evolution of the samples during the experiments have been correlated with models to establish the dominant creep mechanism.

  2. Quantum Dots Confined in Nanoporous Alumina Membranes

    NASA Astrophysics Data System (ADS)

    Xu, Jun; Xia, Jianfeng; Wang, Jun; Shinar, Joseph; Lin, Zhiqun

    2007-03-01

    Precise control over the dispersion and lateral distribution of quantum dots (QDs) within nanoscopic porous media provides a unique route to manipulate the optical and/or electronic properties of QDs in a very simple and controllable manner for applications related to light emitting, optoelectronic, and sensor devices. Here we filled nanoporous alumina membranes (PAMs) with CdSe/ZnS core/shell QDs by dip coating. The deposition of QDs induced changes in the refractive index of PAMs. The amount of absorbed QDs was quantified by fitting the reflection and transmission spectra observed experimentally with one side open and freestanding (i.e., with two sides open) PAMs employed, respectively. The fluorescence of the QDs was found to be retained within the cylindrical nanopores of PAMs.

  3. Nanoporous alumina as templates for multifunctional applications

    NASA Astrophysics Data System (ADS)

    Sousa, C. T.; Leitao, D. C.; Proenca, M. P.; Ventura, J.; Pereira, A. M.; Araujo, J. P.

    2014-09-01

    Due to its manufacturing and size tailoring ease, porous anodic alumina (PAA) templates are an elegant physical-chemical nanopatterning approach and an emergent alternative to more sophisticated and expensive methods currently used in nanofabrication. In this review, we will describe the ground work on the fabrication methods of PAA membranes and PAA-based nanostructures. We will present the specificities of the electrochemical growth processes of multifunctional nanomaterials with diversified shapes (e.g., nanowires and nanotubes), and the fabrication techniques used to grow ordered nanohole arrays. We will then focus on the fabrication, properties and applications of magnetic nanostructures grown on PAA and illustrate their dependence on internal (diameter, interpore distance, length, composition) and external (temperature and applied magnetic field intensity and direction) parameters. Finally, the most outstanding experimental findings on PAA-grown nanostructures and their trends for technological applications (sensors, energy harvesting, metamaterials, and biotechnology) will be addressed.

  4. Aluminum-Alloy-Matrix/Alumina-Reinforcement Composites

    NASA Technical Reports Server (NTRS)

    Kashalikar, Uday; Rozenoyer, Boris

    2004-01-01

    Isotropic composites of aluminum-alloy matrices reinforced with particulate alumina have been developed as lightweight, high-specific-strength, less-expensive alternatives to nickel-base and ferrous superalloys. These composites feature a specific gravity of about 3.45 grams per cubic centimeter and specific strengths of about 200 MPa/(grams per cubic centimeter). The room-temperature tensile strength is 100 ksi (689 MPa) and stiffness is 30 Msi (206 GPa). At 500 F (260 C), these composites have shown 80 percent retention in strength and 95 percent retention in stiffness. These materials also have excellent fatigue tolerance and tribological properties. They can be fabricated in net (or nearly net) sizes and shapes to make housings, pistons, valves, and ducts in turbomachinery, and to make structural components of such diverse systems as diesel engines, automotive brake systems, and power-generation, mining, and oil-drilling equipment. Separately, incorporation of these metal matrix composites within aluminum gravity castings for localized reinforcement has been demonstrated. A composite part of this type can be fabricated in a pressure infiltration casting process. The process begins with the placement of a mold with alumina particulate preform of net or nearly net size and shape in a crucible in a vacuum furnace. A charge of the alloy is placed in the crucible with the preform. The interior of the furnace is evacuated, then the furnace heaters are turned on to heat the alloy above its liquidus temperature. Next, the interior of the furnace is filled with argon gas at a pressure about 900 psi (approximately equal to 6.2 MPa) to force the molten alloy to infiltrate the preform. Once infiltrated, the entire contents of the crucible can be allowed to cool in place, and the composite part recovered from the mold.

  5. The Effect of Fine Alumina Type on Composition of in Situ Spinel Formation in Alumina-Magnesia Castables

    NASA Astrophysics Data System (ADS)

    Paghandeh, M.; Monshi, A.; Emadi, R.

    Three types of low cement castables (LCC) were prepared from 5% reactive alumina (R5), 5% calcined alumina (A5) and equal proportions of 2.5% (AR). The nest of the composition was fine bauxite (0-1 mm, 57%), coarse bauxite (1-3 mm, 20%), calcined magnesia (5%), secar 71 refractory cemet (7%) and microsilica (1%). By the addition of 5% water, castables were moulded, aged, dried and fired to 1400°C for 2 h. XRD studies showed higher amount of in situ spinel formation in A5. The lattice constants of spinels in A5, AR and R5 were, respectively, 8.0348, 8.0688 and 8.0847 Å. This accounted for respectively alumina rich, stochiometry and magnesia rich spinels. Since calcined alumina is cheaper, produce higher amounts of spinel with the aid of alumina from the aggregate of bauxite and the binder of cement, and alumina rich spinel has better corrosion resistance properties, use of calcined alumina is recommended in LCC.

  6. Depression and medication adherence among older Korean patients with hypertension: Mediating role of self-efficacy.

    PubMed

    Son, Youn-Jung; Won, Mi Hwa

    2017-02-13

    Many studies have reported the negative effects of depression on adherence to antihypertensive medication. However, little is known about the mechanism underlying this relationship in elderly patients with hypertension. The aim of this cross-sectional study is to examine the mediating role of self-efficacy in the relationship between depression and medication adherence among older patients with hypertension. The data were collected from October to December 2014. A total of 255 older patients with hypertension were assessed using the Geriatric Depression Scale, the Self-efficacy for Appropriate Medication Use Scale, and the Morisky Medication Adherence Scale. Hierarchical linear regression analysis and the Sobel test were used to examine the mediating role of self-efficacy in the relationship between depression and medication adherence. Depression and self-efficacy were statistically significant predictors of medication adherence in older patients with hypertension. Self-efficacy partially mediated the relationship between depression and medication adherence. Interventions targeting self-efficacy could increase the confidence of patients in their ability to actively take their medicines. Moreover, health care providers should be aware of the importance of early detection of depression in older patients with hypertension. Future studies with longitudinal data are warranted to clarify the multidirectional relationships between depression, self-efficacy, and medication adherence.

  7. Adherence of Pseudomonas aeruginosa to contact lenses

    SciTech Connect

    Miller, M.J.

    1988-01-01

    The purpose of this research was to examined the interactions of P. aeruginosa with hydrogel contact lenses and other substrata, and characterize adherence to lenses under various physiological and physicochemical conditions. Isolates adhered to polystyrene, glass, and hydrogel lenses. With certain lens types, radiolabeled cells showed decreased adherence with increasing water content of the lenses, however, this correlation with not found for all lenses. Adherence to rigid gas permeable lenses was markedly greater than adherence to hydrogels. Best adherence occurred near pH 7 and at a sodium chloride concentration of 50 mM. Passive adhesion of heat-killed cells to hydrogels was lower than the adherence obtained of viable cells. Adherence to hydrogels was enhanced by mucin, lactoferrin, lysozyme, IgA, bovine serum albumin, and a mixture of these macromolecules. Adherence to coated and uncoated lenses was greater with a daily-wear hydrogel when compared with an extended-wear hydrogel of similar polymer composition. Greater adherence was attributed to a higher concentration of adsorbed macromolecules on the 45% water-content lens in comparison to the 55% water-content lens.

  8. Effects of ball milling and sintering on alumina and alumina-boron compounds

    NASA Astrophysics Data System (ADS)

    Cross, Thomas

    Alumina has a wide variety of applications, but the processing of alumina based materials can be costly. Mechanically milling alumina has been shown to enhance the sintering properties while decreasing the sintering temperature. Additions of boron have also proven to increase sintering properties of alumina. These two processes, mechanical milling and boron additions, will be combined to test the sintering properties and determine if they are improved upon even further compared to the individual processes. Multiple samples of pure alumina, 0.2 weight percent boron, and 1.0 weight percent boron are batched and processed in a ball mill for different time intervals. These samples are then characterized to observe the structure and properties of the samples after milling but before sintering. Pellets are dry pressed from the milled powders, sintered at 1200°C for one to 10 hours, and characterized to determine the impact of processing. X-ray diffractometry (XRD) was used on each sample to determine crystallite size and lattice parameters at different stages throughout the experiment. XRD was also used to identify any samples with an aluminum borate phase. Scanning electron microscopy (SEM) was used to observe the powder and pellet morphology and to measure bulk chemical composition. Samples were sputter coated with an Au-Pd coating observed in the SEM to characterize the topography as a function of variables such as milling time, boron composition, and sintering time. Additionally, porosity and change in diameter were measured to track the sintering process. Milling sample for longer periods of time would be unnecessary due to the crystallite size leveling off between 10 and 12 hours of milling time. Samples of alumina with 0.2 weight percent boron prove to have very little effect on the sintering properties. At 1.0 weight percent boron, there are changes in diffraction patterns and topography after being sintered for one hour. The porosities of all of the sintered

  9. Alumina Inlay Failure in Cemented Polyethylene-backed Total Hip Arthroplasty

    PubMed Central

    Iwaki, Hiroyoshi; Minoda, Yukihide; Ohashi, Hirotsugu; Takaoka, Kunio

    2008-01-01

    Alumina-on-alumina bearings for THA have markedly improved in mechanical properties through advances in technology; however, alumina fracture is still a concern. We retrospectively reviewed 77 patients (82 hips) with cemented alumina-on-alumina THAs to identify factors relating to alumina failure. The mean age of the patients at surgery was 63 years. The prostheses had a cemented polyethylene-backed acetabular component with an alumina inlay and a 28-mm alumina head. Revision surgery was performed because of alumina inlay failure in four hips (three fractures and one dissociation; 5.6%), deep infection in two, and recurrent dislocation in one. The 8-year survival rate was 90.7% with revision for any reason and 94.4% with revision for alumina failure as the end point. There were no differences in age, body mass index, gender, mobility, function, abduction angle, or size of component among the four hips with alumina failure and the remaining 68 hips without it; however, radiolucent lines in the sockets were more apparent in four cases with alumina inlay failure. This alumina-on-alumina THA thus yielded unsatisfactory medium-term results because we observed a high rate of catastrophic alumina inlay failure. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18288546

  10. Alumina-Forming MAX Phases in Turbine Material Systems

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Harder, Bryan J.; Garg, Arnita; Nesbitt, James A.

    2015-01-01

    Coatings for high temperature turbine components are based on low conductivity YSZ thermal barriers and protective NiAl, NiCoCrAlY bond coats. Good oxidation hot corrosion resistance, intermediate CTE, and strain tolerance of Ti2AlC and Cr2AlC MAX phases are thus of special interest. Their alumina scale growth follows a cubic law in accord with FeCrAlY alloys, with oxygen grain boundary diffusivity: Dgb 1.8 x 10-10 exp(-375 kJmole) m3s. Protective cubic kinetics are also found in high pressure burner rig (6 atm., 25 ms) and TGA tests of MAXthal 211Ti2AlC. The initial portion (0.1 hr) is dominated by fast TiO2 growth (with little evidence of scale volatility in high pressure water vapor, as found for SiO2 scales). Bulk Ti2AlC and Cr2AlC substrates show promise as potential bond coats for YSZ TBCs in 1000-1200 C furnace life (500 h) tests. Cr2AlC is proving to be very resistant to 700-900 C Na2SO4 hot corrosion and is of interest for disk alloys. Preliminary diffusion bonded Cr2AlC-superalloy hybrid couples have survived 1000 hr interrupted furnace tests at 800C with no indication of cracking or debonding. Diffusion zones of -NiAl+Cr7C3 were produced in these above 1000 C, but did not grow to any great extent after 1000 hr at 800 C. Processing as coatings presents challenges, however the basic properties of MAX phases provide novel opportunities for high temperature turbine components.

  11. Fabrication of whisker-toughened alumina tubes. Final report

    SciTech Connect

    Loutfy, R.O.

    1993-09-01

    A process has been developed to fabricate whisker toughened alumina composites by slip casting dense colloidal suspensions of Al{sub 2}O{sub 3}-15% SiC{sub w}. Optimum processing parameters for slip casting we developed with slip viscosity of 60--70 centipoise and solids content 78--79 wt %. Slip-cast parts with green densities 65 to 68% theoretical were achieved. Composite parts were pressureless sintered to 96--97% theoretical density with <1% open porosity. The composites exhibited strengths of 500 MPa, toughness of 6.5 MPa m{sup 1/2}, and hardness of 17.26 GPa (1765 kg/mm{sup 2}). High temperature strength retention was maintained up to 1200C. Good thermal shock resistance with {Delta}T{sub cr} = 500C was also achieved. The process technology was transferred into pilot scale for producing prototype heat exchanger tubing up to 4 inches in diameter at the facilities of Vesuvius/McDanel.

  12. Removing Fluoride Ions with Continously Fed Activated Alumina.

    ERIC Educational Resources Information Center

    Wu, Yeun C.; Itemaking, Isara Cholapranee

    1979-01-01

    Discussed is the mathematical basis for determining fluoride removal during water treatment with activated alumina. The study indicates that decreasing particle size decreases the pore diffusion effect and increases fluoride removal. (AS)

  13. Growth of Zircone on Nanoporous Alumina Using Molecular Layer Deposition

    NASA Astrophysics Data System (ADS)

    Hall, Robert A.; George, Steven M.; Kim, Yeongae; Hwang, Woonbong; Samberg, Meghan E.; Monteiro-Riviere, Nancy A.; Narayan, Roger J.

    2014-04-01

    Molecular layer deposition (MLD) is a sequential and self-limiting process that may be used to create hybrid organic/inorganic thin films from organometallic precursors and organic alcohol precursors. In this study, films of a zirconium-containing hybrid organic/inorganic polymer known as zircone were grown on nanoporous alumina using MLD. Scanning electron microscopy data showed obliteration of the pores in zircone-coated nanoporous alumina. An in vitro cell viability study indicated that the growth of human epidermal keratinocytes was the greatest on zircone-coated nanoporous alumina than on uncoated nanoporous alumina. Our results suggest that MLD may be used to create biocompatible coatings for use in many types of medical devices.

  14. Potassium Beta-Alumina/Molybdenum/Potassium Electrochemical Cells

    NASA Technical Reports Server (NTRS)

    Williams, R.; Kisor, A.; Ryan, M.; Nakamura, B.; Kikert, S.; O'Connor, D.

    1994-01-01

    potassium alkali metal thermal-to-electric converter (K-AMTEC) cells utilizing potassium beta alumina solid electrolyte (K-BASE) are predicted to have improved properties for thermal to electric conversion at somewhat lower temperatures than sodium AMTEC's.

  15. Fabrication method produces high-grade alumina crucibles

    NASA Technical Reports Server (NTRS)

    Palmour, H.

    1965-01-01

    Alumina-binder mixture, which has been dry pressed in a die using a mating punch, forms crucibles of various configurations and after firing results in a ceramic structure for use in diffusion experiments.

  16. Soil adherence to human skin

    SciTech Connect

    Driver, J.H.; Konz, J.J.; Whitmyre, G.K. )

    1989-12-01

    Dermal exposure to soils contaminated with toxic chemicals represents a potential public health hazard. These soils, contaminated with chemicals such as PCBs and dioxins, may be found at various locations throughout the US. Furthermore, dermal contact with pesticide-containing particles and contaminated soil particles is of importance for exposures to agricultural workers who reenter fields after pesticide application. With respect to dermal exposure to pesticide-contaminated particulate matter, several occurrences of human toxicity to ethyl parathion in citrus groves have been reported. These exposures resulted from dermal contact with high concentrations of the toxic transformation product paraoxon in soil dust contaminated as a result of application of pesticide to the overhead foliage of trees. To assess dermal exposure to chemically-contaminated soil at sites of concern, dermal adherence of soil must be determined prior to the assessment of dermal absorption. The purpose of the experiment reported herein was to determine the amount of soil (mg/cm{sup 2}) that adheres to adult hands under various soil conditions. These conditions include the type of soil, the organic content of the soil, and the particle size of the soil.

  17. Explaining Adherence Success in Sub-Saharan Africa: An Ethnographic Study

    PubMed Central

    Ware, Norma C; Idoko, John; Kaaya, Sylvia; Biraro, Irene Andia; Wyatt, Monique A; Agbaji, Oche; Chalamilla, Guerino; Bangsberg, David R

    2009-01-01

    Background Individuals living with HIV/AIDS in sub-Saharan Africa generally take more than 90% of prescribed doses of antiretroviral therapy (ART). This number exceeds the levels of adherence observed in North America and dispels early scale-up concerns that adherence would be inadequate in settings of extreme poverty. This paper offers an explanation and theoretical model of ART adherence success based on the results of an ethnographic study in three sub-Saharan African countries. Methods and Findings Determinants of ART adherence for HIV-infected persons in sub-Saharan Africa were examined with ethnographic research methods. 414 in-person interviews were carried out with 252 persons taking ART, their treatment partners, and health care professionals at HIV treatment sites in Jos, Nigeria; Dar es Salaam, Tanzania; and Mbarara, Uganda. 136 field observations of clinic activities were also conducted. Data were examined using category construction and interpretive approaches to analysis. Findings indicate that individuals taking ART routinely overcome economic obstacles to ART adherence through a number of deliberate strategies aimed at prioritizing adherence: borrowing and “begging” transport funds, making “impossible choices” to allocate resources in favor of treatment, and “doing without.” Prioritization of adherence is accomplished through resources and help made available by treatment partners, other family members and friends, and health care providers. Helpers expect adherence and make their expectations known, creating a responsibility on the part of patients to adhere. Patients adhere to promote good will on the part of helpers, thereby ensuring help will be available when future needs arise. Conclusion Adherence success in sub-Saharan Africa can be explained as a means of fulfilling social responsibilities and thus preserving social capital in essential relationships. PMID:19175285

  18. Voltage Fluctuations at Sodium Beta Alumina/Mercury Electrodes.

    DTIC Science & Technology

    1987-06-01

    008 VOLTAGE FLUCTUATIONS AT SODIUM 0" ALUMINA/MERCURY ELECTRODES by Chu Kun Kuo* and James J. Brophy Physics Department University of Utah Salt Lake...ADDRESS (Cty. State, and ZIP Code) 7b. ADDRESS (City. State, and ZIP Code) UNIVERSITY OF UTAH UNIVERSITY OF NEW MEXICO SALT LAKE CITY, UTAH 84112...Include Security Classification) VOLTAGE FLUCTUATIONS AT SODIUM BETA" ALUMINA/MERCURY ELECTRODES -, J l.. 0 12 PERSONAL AUTHOR(S) Chu Kun Kuo and James

  19. Superhydrophobic surfaces fabricated by surface modification of alumina particles

    NASA Astrophysics Data System (ADS)

    Richard, Edna; Aruna, S. T.; Basu, Bharathibai J.

    2012-10-01

    The fabrication of superhydrophobic surfaces has attracted intense interest because of their widespread potential applications in various industrial fields. Recently, some attempts have been carried out to prepare superhydrophobic surfaces using metal oxide nanoparticles. In the present work, superhydrophobic surfaces were fabricated with low surface energy material on alumina particles with different sizes. It was found that particle size of alumina is an important factor in achieving stable superhydrophobic surface. It was possible to obtain alumina surface with water contact angle (WCA) of 156° and a sliding angle of <2°. Superhydrophobicity of the modified alumina is attributed to the combined effect of the micro-nanostructure and low surface energy of fatty acid on the surface. The surface morphology of the alumina powder and coatings was determined by FESEM. The stability of the coatings was assessed by conducting water immersion test. Effect of heat treatment on WCA of the coating was also studied. The transition of alumina from hydrophilic to superhydrophobic state was explained using Wenzel and Cassie models. The method is shown to have potential application for creating superhydrophobic surface on cotton fabrics.

  20. Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

    DOEpatents

    Gaffney, T.R.; Golden, T.C.; Mayorga, S.G.; Brzozowski, J.R.; Taylor, F.W.

    1999-06-29

    A pressure swing adsorption process for absorbing CO[sub 2] from a gaseous mixture containing CO[sub 2] comprises introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100 C and 500 C to adsorb CO[sub 2] to provide a CO[sub 2] laden alumina adsorbent and a CO[sub 2] depleted gaseous mixture and contacting the CO[sub 2] laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO[sub 2] from the CO[sub 2] laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100 C and 600 C, is not degraded by high concentrations of water under process operating conditions. 1 fig.

  1. Carbon dioxide pressure swing adsorption process using modified alumina adsorbents

    DOEpatents

    Gaffney, Thomas Richard; Golden, Timothy Christopher; Mayorga, Steven Gerard; Brzozowski, Jeffrey Richard; Taylor, Fred William

    1999-01-01

    A pressure swing adsorption process for absorbing CO.sub.2 from a gaseous mixture containing CO.sub.2 comprising introducing the gaseous mixture at a first pressure into a reactor containing a modified alumina adsorbent maintained at a temperature ranging from 100.degree. C. and 500.degree. C. to adsorb CO.sub.2 to provide a CO.sub.2 laden alumina adsorbent and a CO.sub.2 depleted gaseous mixture and contacting the CO.sub.2 laden adsorbent with a weakly adsorbing purge fluid at a second pressure which is lower than the first pressure to desorb CO.sub.2 from the CO.sub.2 laden alumina adsorbent. The modified alumina adsorbent which is formed by depositing a solution having a pH of 3.0 or more onto alumina and heating the alumina to a temperature ranging from 100.degree. C. and 600.degree. C., is not degraded by high concentrations of water under process operating conditions.

  2. Porous alumina and zirconia ceramics with tailored thermal conductivity

    NASA Astrophysics Data System (ADS)

    Gregorová, E.; Pabst, W.; Sofer, Z.; Jankovský, O.; Matějíček, J.

    2012-11-01

    The thermal conductivity of porous ceramics can be tailored by slip casting and uniaxial dry pressing, using either fugitive pore formers (saccharides) or partial sintering. Porous alumina and zirconia ceramics have been prepared using appropriate powder types (ungranulated for casting, granulated for pressing) and identical firing regimes (but different maximum temperatures in the case of partial sintering). Thermal diffusivities have been measured by the laser- and xenon-flash method and transformed into relative thermal conductivities, which enable a temperature-independent comparison between different materials. While the porosity can be controlled in a similar way for both materials when using pore formers, partial sintering exhibits characteristic differences between alumina and zirconia (for alumina porosities below 45 %, full density above 1600 °C, for zirconia porosities below 60 %, full density above 1300 °C). The different compaction behavior of alumina and zirconia (porosity after pressing 0.465 and 0.597, respectively) is reflected in the fact that for alumina the relative conductivity data of partially sintered materials are below the exponential prediction, while for zirconia they coincide with the latter. Notwithstanding these characteristic differences, for both alumina and zirconia it is possible to tailor the thermal conductivity from 100 % down to approx. 15 % of the solid phase value.

  3. Dynamic yield and tensile strengths of spark plasma sintered alumina

    NASA Astrophysics Data System (ADS)

    Girlitsky, I.; Zaretsky, E.; Kalabukhov, S.; Dariel, M.; Frage, N.

    2014-05-01

    Fully dense alumina samples with 0.6 μm grain size were produced from alumina powder using Spark Plasma Sintering and tested in two types of VISAR-instrumented planar impact tests. In the tests of the first type the samples of 0.28 to 6-mm thickness were loaded by 1-mm tungsten impactors accelerated up to a velocity of about 1 km/s. These tests were aimed to study the Hugoniot elastic limit (HEL) of the SPS-processed alumina and the decay of the elastic precursor wave with propagation distance. In the second type of test the samples of ~3-mm thickness were loaded by 1-mm copper impactors accelerated up to velocities 100-1000 m/s. These tests were aimed to study the dynamic tensile (spall) strength of the alumina. The data on tensile fracture of the alumina demonstrate a monotonic decline of the spall strength with the amplitude of the loading stress pulse. The data on the decay of the elastic precursor wave allows for determining the rates of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of shock-induced inelastic deformation and, thus, to derive some conclusions concerning the mechanisms responsible of the deformation.

  4. Dynamic yield and tensile strengths of spark plasma sintered alumina

    NASA Astrophysics Data System (ADS)

    Girlitsky, Inna; Zaretsky, E.; Kalabukhov, S.; Dariel, M.; Frage, N.

    2013-06-01

    Fully dense alumina samples with 0.6- μ grain size were produced from alumina powder using Spark Plasma Sintering and tested in two types of VISAR-instrumented planar impact tests.. In the tests of the first type the samples of 0.28 to 6-mm thickness were loaded by 1-mm tungsten impactors accelerated up to velocity of about 1 km/s. These tests were aimed to study of the Hugoniot elastic limit (HEL) of the SPS-processed alumina and the decay of the elastic precursor wave with the propagation distance. In the second type of the tests the samples of ~ 3-mm thickness were loaded by 1-mm copper impactors accelerated up to velocities 100-1000 m/s was. These tests were aimed to the study of the dynamic tensile (spall) strength of the alumina. The data on the decay of the elastic precursor wave allow determining the rates of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced plastic deformation and, thus, to derive some conclusions concerning the mechanisms responsible of the deformation. The data on the tensile fracture of the alumina demonstrate a monotonous decline of the spall strength with the amplitude of the loading stress pulse.

  5. Wetting and strength issues at Al/alpha-alumina interfaces

    SciTech Connect

    Saiz, Eduardo; Tomsia, Antoni P.; Suganuma, Katsuaki

    2003-04-15

    The wetting behavior and strength at aluminum/alumina interfaces has been an active subject of research. Al/alumina applications include ceramic-metal composites and several applications for electronic industries. In this paper the interface strength and microstructure of Al/alpha-alumina was investigated. We discovered that in a solid-state joining, the strength of the joint increases with increasing joining temperature. In a liquid-state joining, the strength of the joint gradually decreases due to the formation of unbonded areas. The strength, sigma sub b, is expressed by the following equation as a function of unbonded area, A: sigma sub b = 2.22 A + 143 (70 percent {le} A {le} 100 percent). The highest strength reached 400 MPa when the interface was formed at around the melting temperature of aluminum. An aluminum layer close to the interface became a single crystal when it was bonded to a sapphire. The following crystallographic orientation relationship is established: (1{bar 1}1){sub Al}//(001){sub {alpha}}-Al{sub 2} O{sub 3}, (110){sub Al}//<100>{sub {alpha}}-Al{sub 2}O{sub 3}. Amorphous alumina islands were formed at the interface. In the amorphous alumina, gamma-alumina nanocrystals grew from the sapphire, with the same orientation relationship to sapphire as above.

  6. Factors influencing bacterial adherence to biomaterials.

    PubMed

    Merritt, K; Chang, C C

    1991-01-01

    The adherence of bacteria to implanted medical devices is believed to be important in the development of implant associated infections. Measures which reduce bacterial adherence should reduce the incidence of these infections. However, in order to assess the importance of adherence, the effectiveness of methods to reduce adherence, and compare data from different laboratories, the conditions of the in vitro studies on adherence need to be specified. There are currently no correct and incorrect methods, however, methods used need to be carefully described. The studies reported here indicate that the definition of adherence needs to be established, with the use of polystyrene as the reference material recommended. Since the adherent organisms lose adherence traits with culture, cultures must be selected for adherence regularly. It is important to control the number of organisms/ml but the volume used is not important. The medium used to grow the organisms and the use of stationary, rocking or flow conditions will alter adherence and need to be specified and be consistent within a set of experiments. Culture conditions, methods of rinsing the material, methods of elution and counting, or direct counting of organisms on the material need to be specified. Finally, as much information as possible on the bulk and surface properties of the material should be provided. The handling of the material for the experiments should be careful and defined. Fingerprints, contact with protein, wet surfaces vs dry surfaces, etc., will all affect the subsequent adherence. The materials should not be re-used since the removal of the adherent proteins or the biofilm is very difficult. Progress can be made in this important area if the details of procedures are specified.

  7. Geriatric syndromes are potential determinants of the medication adherence status in prevalent dialysis patients

    PubMed Central

    Chao, Chia-Ter

    2016-01-01

    Background. Geriatric syndromes (GS) exhibit high prevalence in patients with end-stage renal disease (ESRD) under chronic dialysis irrespective of age. We sought to determine whether GS influences medication adherence in ESRD patients. Methods. A prospective cohort of chronic dialysis patients was assembled. The presence of GS components, including frailty/prefrailty, polypharmacy, and malnutrition, were ascertained through a validated questionnaire, electronic records and chart abstraction, and laboratory tests. The severity of medication non-adherence was defined using the eight-item Morisky Medication Adherence Scale (MMAS). Multiple logistic regression analysis was performed targeting MMAS results and incorporating relevant clinical features and GS. Results. The prevalence of frailty/pre-frailty, polypharmacy, and hypoalbuminemia/ malnutrition among the enrolled participants was 66.7%, 94%, and 14%, respectively. The average MMAS scores in these dialysis patients were 2 ± 1.7 (range, 0–6), with only 15.7% exhibiting high medication adherence. Multiple regression analyses showed that the absence of frailty/pre-frailty (P = 0.01) were significantly associated with poorer medication adherence, while the presence of polypharmacy (P = 0.02) and lower serum albumin, a potential sign of malnutrition (P = 0.03), were associated with poor adherence in another model. Conclusion. This study is among the very few reports addressing GS and medication adherence, especially in ESRD patients. Interventions targeting frailty, polypharmacy, and malnutrition might potentially improve the medication non-adherence and symptom control in these pill-burdened patients. PMID:27326380

  8. Medication Adherence: A Call for Action

    PubMed Central

    Bosworth, Hayden B.; Granger, Bradi B.; Mendys, Phil; Brindis, Ralph; Burkholder, Rebecca; Czajkowski, Susan M.; Daniel, Jodi G.; Ekman, Inger; Ho, Michael; Johnson, Mimi; Kimmel, Stephen E.; Liu, Larry Z; Musaus, John; Shrank, William H.; Buono, Elizabeth Whalley; Weiss, Karen; Granger, Christopher B.

    2013-01-01

    Poor adherence to efficacious cardiovascular related medications has led to considerable morbidity, mortality, and avoidable health care costs. This paper provides results of a recent think tank meeting in which various stakeholder groups representing key experts from consumers, community health providers, the academic community, decision-making government officials (FDA, NIH, etc), and industry scientists met to evaluate the current status of medication adherence and provide recommendations for improving outcomes. Below, we review the magnitude of the problem of medication adherence, prevalence, impact, and cost. We then summarize proven effective approaches and conclude with a discussion of recommendations to address this growing and significant public health issue of medication non adherence. PMID:21884856

  9. Selected factors affecting adherence in the pharmacological treatment of arterial hypertension

    PubMed Central

    Jankowska-Polańska, Beata; Chudiak, Anna; Uchmanowicz, Izabella; Dudek, Krzysztof; Mazur, Grzegorz

    2017-01-01

    Background Low adherence to hypertension (HT) management is one of the major contributors to poor blood pressure (BP) control. Approximately 40%–60% of patients with HT do not follow the prescribed treatment. The aim of the study was to analyze the relationship between selected variables and adherence to hypotensive pharmacological treatment. Besides socioclinical variables, the study focused on the role of illness acceptance. Participants and methods The study included 602 patients with HT. Adherence and acceptance of illness were assessed using the following validated instruments: the Acceptance of Illness Scale (AIS) and the Morisky Medication Adherence Scale (MMAS). Results The high-adherence group comprised a significantly higher percentage of patients with high illness acceptance scale scores than that of patients with low-to-moderate scores (42.4 vs 31.8%; P=0.008<0.01). The odds ratio (OR) showed that high adherence to pharmacological treatment was >1.5 times as likely to occur in the high acceptance group as in the low-to-moderate acceptance group (OR =1.58, 95% CI 1.14–2.19). Spearman’s rank correlation coefficients showed statistically significant correlations between adherence and sex (men ρ=−0.101; P=0.012), age >45–66 years (ρ=0.098; P=0.015), higher education level (ρ=0.132; P=0.001), grade ESC of HT (ρ=−0.037; P=0.057), receiving one-tablet polytherapy (ρ=0.131; P=0.015), and illness acceptance (ρ=0.090; P=0.024). Conclusion Acceptance of illness is correlated with adherence to pharmacological treatment, and consideration should be given to more widespread assessment of illness acceptance in daily practice. Male sex, age >45–66 years, duration of illness grade ESC of HT, and receiving one-tablet polytherapy are significant determinants of adherence to pharmacological treatment in HT. PMID:28280309

  10. Edge-defined film-fed growth of beta-alumina and Mg-substituted beta-alumina

    NASA Technical Reports Server (NTRS)

    Morrison, A. D.; Stormont, R. W.; Cocks, F. H.

    1975-01-01

    High Na vapor pressure, peritectic decomposition, and high reactivity of the melt complicate the growth of beta-alumina crystals. These difficulties were overcome by using a high-pressure (300 psig) growth chamber, Na2O-rich melts, and Ir for all surfaces in contact with the melt. These procedures were combined with the edge-defined film-fed growth technique to produce single-crystal beta-alumina tubes and ribbons.

  11. Effect of alumina composition and surface integrity in alumina/epoxy composites on the ultrasonic attenuation properties.

    PubMed

    Cho, Eikhyun; Park, Gwanwoo; Lee, Jae-Wan; Cho, Sung-Min; Kim, Taekyung; Kim, Joongeok; Choi, Wonjoon; Ohm, Won-Suk; Kang, Shinill

    2016-03-01

    We report a method of fabricating backing blocks for ultrasonic imaging transducers, using alumina/epoxy composites. Backing blocks contain scatterers such as alumina particles interspersed in the epoxy matrix for the effective scattering and attenuation of ultrasound. Here, the surface integrity can be an issue, where the composite material may be damaged during machining because of differences in strength, hardness and brittleness of the hard alumina particles and the soft epoxy matrix. Poor surface integrity results in the formation of air cavities between the backing block and the piezoelectric element upon assembly, hence the increased reflection off the backing block and the eventual degradation in image quality. Furthermore, with an issue of poor surface integrity due to machining, it is difficult to increase alumina as scatterers more than a specific mass fraction ratio. In this study, we increased the portion of alumina within epoxy matrix by obtaining an enhanced surface integrity using a net shape fabrication method, and verified that this method could allow us to achieve higher ultrasonic attenuation. Backing blocks were net-shaped with various mass fractions of alumina to characterize the formability and the mechanical properties, including hardness, surface roughness and the internal micro-structure, which were compared with those of machined backing blocks. The ultrasonic attenuation property of the backing blocks was also measured.

  12. Adherence of sputtered titanium carbides

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Wheeler, D. R.

    1979-01-01

    The study searches for interface treatment that would increase the adhesion of TiC coating to nickel- and titanium-base alloys. Rene 41 (19 wt percent Cr, 11 wt percent Mo, 3 wt percent Ti, balance Ni) and Ti-6Al-4V (6 wt percent Al, 4 wt percent V, balance Ti) are considered. Adhesion of the coatings is evaluated in pin-and disk friction tests. The coatings and interface regions are examined by X-ray photoelectron spectroscopy. Results suggest that sputtered refractory compound coatings adhere best when a mixed compound of coating and substrate metals is formed in the interfacial region. The most effective type of refractory compound interface appears to depend on both substrate and coating material. A combination of metallic interlayer deposition and mixed compound interface formation may be more effective for some substrate coating combinations than either alone.

  13. Microstructure evolution and densification of alumina in liquid phase sintering

    NASA Astrophysics Data System (ADS)

    Dong, Weimin

    The microstructure evolution and densification of alumina during liquid phase sintering were quantified. Quantification included the evolution of pore-size distribution, the redistribution of liquid phase, the densification kinetics, and the fraction of closed and open pores. The results revealed that the small and large pores were filled simultaneously. This is inconsistent with Shaw's model in which liquid fills preferentially the smaller low-coordination-number pores in order to reach a low-energy configuration. The results also recommended that the pressure build-up of the trapped gases in pores due to the closure of open pores might have a significantly negative contribution to the driving force, and consequently cause the termination of the densification of alumina. To demonstrate whether the trapped gases played an important role in the microstructure evolution and the densification of alumina during liquid phase sintering, the following two experiments have been conducted. First, alumina preforms containing artificial pores were penetrated by glass. The results indicated that the trapped gases in pores had a considerable influence on the pore filling process, and ultimately caused the termination of the densification of the alumina preforms. Second, alumina compacts containing different amount of glass were sintered in vacuum. The alumina compact containing 20 vol. % reached full density during vacuum sintering, indicating that the pressure build-up of the trapped gases in pores was the main factor causing the termination of the densification of alumina in the final stage of liquid phase sintering. The limiting relative densities of compacts were calculated theoretically on the basis of a comprehensive analysis of the variation of the capillary pressure and gas pressure in pores with pore size and pore number. The capillary pressure and gas pressure in alumina compact during liquid phase sintering were analyzed on the basis of the above theoretical models

  14. Adherence in ulcerative colitis: an overview

    PubMed Central

    Testa, Anna; Castiglione, Fabiana; Nardone, Olga Maria; Colombo, Giorgio L

    2017-01-01

    Medication adherence is an important challenge while treating chronic illnesses, such as ulcerative colitis (UC), that require a long-term management to induce and maintain clinical remission. This review provides an overview of the role that medication adherence plays in the routine management of UC, with a focus on the results of a recent Italian study reporting the perception of patients with UC regarding adherence to treatment. A literature analysis was conducted on topics, such as measurement of adherence in real practice, causes, risk factors and consequences of non-adherence and strategies, to raise patients’ adherence. Most of the data refer to adherence to 5-aminosalicylic acid, and standard of care for the induction and maintenance of remission in UC. The adherence rate to 5-aminosalicylic acid is low in clinical practice, thus resulting in fivefold higher risk of relapse, likely increased risk of colorectal cancer, reduced quality of life and higher health care costs for in- and outpatient settings. There are various causes affecting non-adherence to therapy: forgetfulness, high cost of drugs, lack of understanding of the drug regimen – which are sometimes due to insufficient explanation by the specialist – anxiety created by possible adverse events, lack of confidence in physicians’ judgment and complex dosing regimen. The last aspect negatively influences adherence to medication both in clinical trial settings and in real-world practice. Regarding this feature, mesalamine in once-daily dosage may be preferable to medications with multiple doses per day because the simplification of treatment regimens improves adherence. PMID:28260866

  15. Joining of alumina by vacuum brazing

    NASA Astrophysics Data System (ADS)

    Heikinheimo, Liisa; Siren, Mika; Kauppinen, Pentti

    1993-08-01

    The active brazing method for diffusion bonding of ceramics to metals is addressed. This method is very flexible compared to the traditional Mo-manganese coating with subsequent brazing that includes four process steps: in active brazing the process is done in one step. The joint properties are favorable, the residual stress build up is limited if the braze is correctly selected and the thermal cycle is controlled, and the resulting strength and leak tightness are good. In experimental work the joinability of alumina to titanium and Ni superalloys was studied by wetting experiments, nondestructive test and shear strength measurements. The spreading of the braze is affected not only by the surface conditions of mating materials but also by the type of the brazing alloy. The Ag-Cu base alloys give better wetting, strength and leak tightness properties than the Ag base alloys. A shear test method was developed for the mechanical testing of metal-ceramic joints. However, the sample geometry affects the measured values, namely a smaller specimen size provides better results. The correlation between the C-SAM results, which describe the ratio between the true bonded area and unbonded area, and measured shear strength values is presented. The dependence between the measured strength and the area of the joint defects becomes obvious and should be studied in more detail.

  16. Thermal Conductivity of Alumina and Silica Nanofluids

    NASA Astrophysics Data System (ADS)

    Castellanos, Julian G. Bernal

    This thesis studies the effects of the base fluid, particle type/size, and volumetric concentration on the thermal conductivity of Alumina and Silica nanofluids. The effects of base fluid were observed by preparing samples using ethylene glycol (EG), water, and mixtures of EG/water as the base fluid and Al2O3 (10 nm) nanoparticles. The particles type/size and volumetric concentration effects were tested by preparing samples of nanofluids using Al2O3 (10nm), Al2O3 (150nm), SiO2 (15 nm), and SiO2 (80 nm) nanoparticles and ionized water as base fluid at different volumetric concentrations. All samples were mixed using a sonicator for 30 minutes and a water circulator to maintain the sample at room temperature. The thermal conductivity was measured using a Thermtest Transient Plane Source TPS 500S. The effects of gravity, Brownian motion and thermophoresis were also studied. EG produced the highest thermal conductivity enhancement out of all base fluids tested. Smaller particle size produced a higher enhancement of thermal conductivity, while the volumetric concentration did not have a significant effect in the thermal conductivity enhancement. Finally, gravity, Brownian diffusion and thermophoresis effects played a role in the total enhancement of the thermal conductivity. The nanoparticles were observed to settle rapidly after sonication suggesting gravity effects may play a significant role.

  17. Annealing Would Improve beta" - Alumina Solid Electrolyte

    NASA Technical Reports Server (NTRS)

    Williams, Roger; Homer, Margie; Ryan, Margaret; Cortez, Roger; Shields, Virgil; Kisor, Adam

    2003-01-01

    A pre-operational annealing process is under investigation as a potential means of preventing a sudden reduction of ionic conductivity in a Beta"-alumina solid electrolyte (BASE) during use. On the basis of tests, the sudden reduction of ionic conductivity, followed by a slow recovery, has been found to occur during testing of the solid electrolyte and electrode components of an alkali metal thermal-to-electric converter (AMTEC) cell. At this time, high-temperature tests of limited duration have indicated the superiority of the treated BASE, but reproducible tests over thousands of hours are necessary to confirm that microcracking has been eliminated. The ionic conductivity of the treated BASE is also measured to be higher than untreated BASE at 1,073 K in low-pressure sodium vapor. Microcracking resulting in loss of conductivity was not observed with treated BASE in one high-temperature experiment, but this result must be duplicated over very long testing times to be sure of the effect. Shorter annealing times (10 to 20 hours) were found to result in significantly less loss of mass; it may be necessary for the packed powder mixture to evolve some Na2O before the Na2O can leave the ceramic.

  18. Mechanical properties of alumina porcelain during heating

    NASA Astrophysics Data System (ADS)

    Šín, Peter; Podoba, Rudolf; ŠtubÅa, Igor; Trník, Anton

    2014-11-01

    The mechanical strength and Young's modulus of green alumina porcelain (50 wt. % of kaolin, 25 wt. % of Al2O3, and 25 wt. % of feldspar) were measured during heating up to 900 °C and 1100 °C, respectively. To this end, we used the three point-bending method and modulated force thermomechanical analysis (mf-TMA). The loss liberation - of the physically bound water (20 - 250 °C) strengthens the sample and Young's modulus increases its values significantly. The dehydroxylation that takes place in the range of 400 - 650 °C causes a slight decrease in Young's modulus. On the other hand, the mechanical strength slightly increases in this temperature range, although it has a sudden drop at 420 °C. Beyond the dehydroxylation range, above 650 °C, both Young's modulus and mechanical strength increase. Above 950 °C, a sharp increase of Young's modulus is caused by the solid-state sintering and the new structure created by the high-temperature reactions in metakaolinite.

  19. Effect of Zirconia and Alumina Fillers on the Microstructure and Mechanical Strength of Dental Glass Ionomer Cements

    PubMed Central

    Souza, Júlio C. M.; Silva, Joel B.; Aladim, Andrea; Carvalho, Oscar; Nascimento, Rubens M.; Silva, Filipe S.; Martinelli, Antonio E.; Henriques, Bruno

    2016-01-01

    Background: Glass-ionomer cements perform a protective effect on the dentin-pulp complex considering the F ions release and chemical bonding to the dental structures. On the other hand, those materials have poor physic-mechanical properties in comparison with the restorative resin composite. The main aim of this work was to evaluate the influence of zirconia and/or alumina fillers on the microstructure and strength of a resin modified glass-ionomer cement after thermal cycling. Methods: An in vitro experimental study was carried out on 9 groups (n = 10) of cylindrical samples (6 x 4 mm) made from resin modified glass-ionomer (Vitremer, 3M, USA) with different contents of alumina and/or zirconia fillers. A nano-hybrid resin composite was tested as a control group. Samples were mechanically characterized by axial compressive tests and electron scanning microscopy (SEM) coupled to energy dispersive X-ray spectrophotometry (EDS), before and after thermal cycling. Thermal cycling procedures were performed at 3000, 6000 and 10000 cycles in Fusayama´s artificial saliva at 5 and 60 oC. Results: An improvement of compressive strength was noticed on glass-ionomer reinforced with alumina fillers in comparison with the commercial glass ionomer. SEM images revealed the morphology and distribution of alumina or zirconia in the microstructure of glass-ionomers. Also, defects such as cracks and pores were detected on the glass-ionomer cements. The materials tested were not affected by thermal cycling in artificial saliva. Conclusion: Addition of inorganic particles at nano-scale such as alumina can increase the mechanical properties of glass-ionomer cements. However, the presence of cracks and pores present in glass-ionomer can negatively affect the mechanical properties of the material because they are areas of stress concentration. PMID:27053969

  20. Ion polarization behavior in alumina under pulsed gate bias stress

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Diallo, Abdou Karim; Katz, Howard E.

    2015-03-01

    Alkali metal ion incorporation in alumina significantly increases alumina capacitance by ion polarization. With high capacitance, ion-incorporated aluminas become promising high dielectric constant (high-k) gate dielectric materials in field-effect transistors (FETs) to enable reduced operating voltage, using oxide or organic semiconductors. Alumina capacitance can be manipulated by incorporation of alkali metal ions, including potassium (K+), sodium (Na+), and lithium (Li+), having different bond strengths with oxygen. To investigate the electrical stability of zinc tin oxide-based transistors using ion incorporated alumina as gate dielectrics, pulsed biases at different duty cycles (20%, 10%, and 2% representing 5 ms, 10 ms, and 50 ms periods, respectively) were applied to the gate electrode, sweeping the gate voltage over series of these cycles. We observed a particular bias stress-induced decrease of saturation field-effect mobility accompanied by threshold voltage shifts (ΔVth) in potassium and sodium-incorporated alumina (abbreviated as PA and SA)-based FETs at high duty cycle that persisted over multiple gate voltage sweeps, suggesting a possible creation of new defects in the semiconductor. This conclusion is also supported by the greater change in the mobility-capacitance (μC) product than in capacitance itself. Moreover, a more pronounced ΔVth over shorter times was observed in lithium-incorporated alumina (abbreviated as LA)-based transistors, suggesting trapping of electrons in existing interfacial states. ΔVth from multiple gate voltage sweeps over time were fit to stretched exponential forms. All three dielectrics show good stability using 50-ms intervals (20-Hz frequencies), corresponding to 2% duty cycles.

  1. Ion polarization behavior in alumina under pulsed gate bias stress

    SciTech Connect

    Liu, Yu; Diallo, Abdou Karim; Katz, Howard E.

    2015-03-16

    Alkali metal ion incorporation in alumina significantly increases alumina capacitance by ion polarization. With high capacitance, ion-incorporated aluminas become promising high dielectric constant (high-k) gate dielectric materials in field-effect transistors (FETs) to enable reduced operating voltage, using oxide or organic semiconductors. Alumina capacitance can be manipulated by incorporation of alkali metal ions, including potassium (K{sup +}), sodium (Na{sup +}), and lithium (Li{sup +}), having different bond strengths with oxygen. To investigate the electrical stability of zinc tin oxide-based transistors using ion incorporated alumina as gate dielectrics, pulsed biases at different duty cycles (20%, 10%, and 2% representing 5 ms, 10 ms, and 50 ms periods, respectively) were applied to the gate electrode, sweeping the gate voltage over series of these cycles. We observed a particular bias stress-induced decrease of saturation field-effect mobility accompanied by threshold voltage shifts (ΔV{sub th}) in potassium and sodium-incorporated alumina (abbreviated as PA and SA)-based FETs at high duty cycle that persisted over multiple gate voltage sweeps, suggesting a possible creation of new defects in the semiconductor. This conclusion is also supported by the greater change in the mobility-capacitance (μC) product than in capacitance itself. Moreover, a more pronounced ΔV{sub th} over shorter times was observed in lithium-incorporated alumina (abbreviated as LA)-based transistors, suggesting trapping of electrons in existing interfacial states. ΔV{sub th} from multiple gate voltage sweeps over time were fit to stretched exponential forms. All three dielectrics show good stability using 50-ms intervals (20-Hz frequencies), corresponding to 2% duty cycles.

  2. A Review of Treatment Adherence Measurement Methods

    ERIC Educational Resources Information Center

    Schoenwald, Sonja K.; Garland, Ann F.

    2013-01-01

    Fidelity measurement is critical for testing the effectiveness and implementation in practice of psychosocial interventions. Adherence is a critical component of fidelity. The purposes of this review were to catalogue adherence measurement methods and assess existing evidence for the valid and reliable use of the scores that they generate and the…

  3. Current Situation of Medication Adherence in Hypertension

    PubMed Central

    Vrijens, Bernard; Antoniou, Sotiris; Burnier, Michel; de la Sierra, Alejandro; Volpe, Massimo

    2017-01-01

    Despite increased awareness, poor adherence to treatments for chronic diseases remains a global problem. Adherence issues are common in patients taking antihypertensive therapy and associated with increased risks of coronary and cerebrovascular events. Whilst there has been a gradual trend toward improved control of hypertension, the number of patients with blood pressure values above goal has remained constant. This has both personal and economic consequences. Medication adherence is a multifaceted issue and consists of three components: initiation, implementation, and persistence. A combination of methods is recommended to measure adherence, with electronic monitoring and drug measurement being the most accurate. Pill burden, resulting from free combinations of blood pressure lowering treatments, makes the daily routine of medication taking complex, which can be a barrier to optimal adherence. Single-pill fixed-dose combinations simplify the habit of medication taking and improve medication adherence. Re-packing of medication is also being utilized as a method of improving adherence. This paper presents the outcomes of discussions by a European group of experts on the current situation of medication adherence in hypertension. PMID:28298894

  4. Adherence to Pharmacotherapy and Medication-Related Beliefs in Patients with Hypertension in Lima, Peru

    PubMed Central

    Miranda, J. Jaime; Diez-Canseco, Francisco; Malaga, German

    2014-01-01

    Objective To characterize adherence to pharmacological medication and beliefs towards medication in a group of patients with hypertension in a large national hospital. Materials and Methods Cross-sectional survey among patients with hypertension attending the outpatient clinic of a large national hospital. Exposure of interest was the patient's beliefs towards general medication and antihypertensive drugs, i.e. beliefs of harm, overuse, necessity and concern, measured using the Beliefs about Medication questionnaire. Main outcome was adherence measured using the Morisky Medication Adherence Scale-8. Multivariate analysis was conducted using Poisson distribution logistic regression, prevalence ratios and 95% confidence intervals were calculated. Results Data from 115 participants, 67% females and mean age 62.7 years were analyzed. Low adherence was found in 57.4%. Highest scores were on the ideas of necessity and one of the most rated statements was “physicians would prescribe less medication if they spent more time with patients”. Beliefs of harm about medications and concerns about antihypertensive drugs were higher in the low adherence group (p<0.01). Those who scored higher on ideas of harm were 52% less likely of being high adherents (PR 0.48; 95% CI 0.25–0.93) and those with higher scores on concerns were 41% less likely of being high adherents (PR 0.59; 95% CI 0.39–0.91). Patients whose ideas of necessity outweighed their concerns were more likely to be adherent (PR 2.65; 95% CI 1.21–5.81). Conclusions Low adherence to antihypertensive medication is common. High scores on ideas of harm, concern and a high necessity-concern differential were predictors of medication adherence. PMID:25470372

  5. The influence of frailty syndrome on medication adherence among elderly patients with hypertension

    PubMed Central

    Jankowska-Polańska, Beata; Dudek, Krzysztof; Szymanska-Chabowska, Anna; Uchmanowicz, Izabella

    2016-01-01

    Background Hypertension affects about 80% of people older than 80 years; however, diagnosis and treatment are difficult because about 55% of them do not adhere to treatment recommendations due to low socioeconomic status, comorbidities, age, physical limitations, and frailty syndrome. Aims The purposes of this study were to evaluate the influence of frailty on medication adherence among elderly hypertensive patients and to assess whether other factors influence adherence in this group of patients. Methods and results The study included 296 patients (mean age 68.8±8.0) divided into frail (n=198) and non-frail (n=98) groups. The Polish versions of the Tilburg Frailty Indicator (TFI) for frailty assessment and 8-item Morisky Medication Adherence Scale for adherence assessment were used. The frail patients had lower medication adherence in comparison to the non-frail subjects (6.60±1.89 vs 7.11±1.42; P=0.028). Spearman’s rank correlation coefficients showed that significant determinants with negative influence on the level of adherence were physical (rho =−0.117), psychological (rho =−0.183), and social domain (rho =−0.163) of TFI as well as the total score of the questionnaire (rho =−0.183). However, multiple regression analysis revealed that only knowledge about complications of untreated hypertension (β=0.395) and satisfaction with the home environment (β=0.897) were found to be independent stimulants of adherence level. Conclusion Frailty is highly prevalent among elderly hypertensive patients. Higher level of frailty among elderly patients can be considered as a determinant of lower adherence. However, social support and knowledge about complications of untreated hypertension are the most important independent determinants of adherence to pharmacological treatment. PMID:27994444

  6. Factors influencing medication knowledge and beliefs on warfarin adherence among patients with atrial fibrillation in China

    PubMed Central

    Zhao, Shujuan; Zhao, Hongwei; Wang, Xianpei; Gao, Chuanyu; Qin, Yuhua; Cai, Haixia; Chen, Boya; Cao, Jingjing

    2017-01-01

    Objectives Warfarin is often used for ischemic stroke prevention in patients with atrial fibrillation (AF), but the factors affecting patient adherence to warfarin therapy have not been fully understood. Methods A cross-sectional survey was conducted in AF patients undergoing warfarin therapy at least 6 months prior to the study. The clinical data collected using questionnaires by phone interviews included the following: 1) self-reported adherence measured by the Morisky Medication Adherence Scale-8©; 2) beliefs about medicines surveyed by Beliefs about Medicines Questionnaire (BMQ); and 3) drug knowledge as measured by the Warfarin Related Knowledge Test (WRKT). Demographic and clinical factors associated with warfarin adherence were identified using a logistic regression model. Results Two hundred eighty-eight patients completed the survey and 93 (32.3%) of them were classified as nonadherent (Morisky Medication Adherence Scale-8 score <6). Major factors predicting warfarin adherence included age, cardiovascular disorders, WRKT, and BMQ; WRKT and BMQ were independently correlated with adherence to warfarin therapy by multivariate logistic regression analysis. Adherents were more likely to have greater knowledge scores and stronger beliefs in the necessity of their specific medications ([odds ratio {OR} =1.81, 95% confidence interval {CI} =1.51–2.15] and [OR =1.17, 95% CI =1.06–1.29], respectively). Patients with greater concerns about adverse reactions and more negative views of general harm were more likely to be nonadherent ([OR =0.76, 95% CI =0.69–0.84] and [OR =0.82, 95% CI =0.73–0.92], respectively). Conclusion BMK and WRKT are related with patient behavior toward warfarin adherence. BMQ can be applied to identify patients at increased risk of nonadherence. PMID:28223782

  7. Adherence to Treatment and Factors Affecting Adherence of Epileptic Patients at Yirgalem General Hospital, Southern Ethiopia: A Prospective Cross-Sectional Study

    PubMed Central

    Hasiso, Temesgen Yohannes; Desse, Tigestu Alemu

    2016-01-01

    Background Non adherence of epileptic patients to antiepileptic medication often leads to an increased risk of seizures and worsening of disease, death and increased health care costs. Objective to assess adherence to treatment and factors affecting adherence of epileptic patients at Yirgalem General Hospital, Southern Ethiopia. Methods and Materials We conducted a cross-sectional study on epileptic patients from February 9 to 22, 2015. Data were collected from patients ≥18 years old. Adherence was measured using the eight-item Morisky’s medication adherence scale. All consecutive patients coming to epilepsy clinic during the study period were interviewed until the calculated sample size (210) was obtained. We collected patient demographics, perception about epilepsy and adherence to medication(s). We used chi-square tests and a binary logistic regression model for statistical analysis. Statistical significance was considered at P<0.05. Results out of a total of 210 participants, 194 were willing to participate and were studied. Of the 194 participants, 109 (56.2%) were males. The mean age of the participants was 33.62±11.44 years; range 18 to 66 years. The majority, 123(63.41%), of the participants were taking two antiepileptic medications. Sixty two (32%) of the participants were adherent to their treatment. The most common reported reasons for non-adherence were forgetfulness 49(75.4%) and run out of pills 7(10.8%). Factors that affect medication adherence are epilepsy treatment for <1 year (P = 0.011), epilepsy treatment for 1–3 years (P = 0.002), epilepsy treatment for 3–5 years (P = 0.007), being married (P = 0.006), grade 9–12 education (P = 0.028), college or university education (P = 0.002) and absence of co-morbidity (P = 0.008). Conclusions The rate of adherence observed in this study was low. The most common reason for non- adherence was forgetfulness. Therefore, the hospital should devise strategies to improve adherence of epileptic patients

  8. Motivating patient adherence to allergic rhinitis treatments.

    PubMed

    Bender, Bruce G

    2015-03-01

    Patient nonadherence significantly burdens the treatment of allergic rhinitis (AR). Fewer than half of prescribed doses of intranasal corticosteroid medication are taken. The challenges for immunotherapies are even greater. While sustained treatment for 3 to 5 years is required for full benefit, most patients receiving immunotherapy, either subcutaneous or sublingual, stop treatment within the first year. Although research into interventions to improve AR adherence is lacking, lessons learned from adherence interventions in other chronic health conditions can be applied to AR. Two well-established, overriding models of care-the chronic care model and patient-centered care-can improve adherence. The patient-centered care model includes important lessons for allergy providers in their daily practice, including understanding and targeting modifiable barriers to adherence. Additionally, recent studies have begun to leverage health information and communication technologies to reach out to patients and promote adherence, extending patient-centered interventions initiated by providers during office visits.

  9. An evaluation of factors affecting adherence to antiepileptic drugs in patients with epilepsy: a cross-sectional study

    PubMed Central

    Gurumurthy, Ranjana; Chanda, Kulkarni; Sarma, GRK

    2017-01-01

    INTRODUCTION Adherence to antiepileptic drug (AED) therapy is important for controlling seizures in patients with epilepsy (PWE). It is vital to identify the factors influencing adherence to AED therapy using validated tools. This study aimed to evaluate the pattern and extent of AED adherence among PWE and to identify the factors that influence adherence. METHODS This was a cross-sectional study involving PWE who had a confirmed diagnosis. Treatment adherence was assessed using the four-item Morisky Medication Adherence Scale. Univariate analysis with chi-square test was used to observe the association between different variables and AED adherence. Binary logistic regression analysis was used to identify the predictors of adherence. RESULTS 451 PWE (mean age 27.3 ± 8.1 years) were enrolled in the study; 251 (55.7%) were male and 198 (43.9%) were from the lower socioeconomic class. 326 (72.3%) patients had high adherence to AED therapy, while 125 (27.7%) had low adherence. AED adherence was significantly associated with socioeconomic status (p = 0.043) and type of epilepsy (p = 0.033). However, no significant difference was observed between adherence and age, gender, marital status, epilepsy duration, number and type of AEDs, and occurrence of adverse drug reactions. Patients with focal epilepsy and those from the middle/lower-middle socioeconomic classes were less likely to be nonadherent. The primary reason for nonadherence was forgetfulness. CONCLUSION This study found that a majority of PWE have optimal rates of AED adherence and that forgetfulness is the primary reason for nonadherence among PWE. PMID:26805666

  10. A Self-Reported Adherence Measure to Screen for Elevated HIV Viral Load in Pregnant and Postpartum Women on Antiretroviral Therapy

    PubMed Central

    Brittain, Kirsty; Mellins, Claude A.; Zerbe, Allison; Remien, Robert H.; Abrams, Elaine J.; Myer, Landon; Wilson, Ira B.

    2016-01-01

    Maternal adherence to antiretroviral therapy (ART) is a concern and monitoring adherence presents a significant challenge in low-resource settings. We investigated the association between self-reported adherence, measured using a simple three-item scale, and elevated viral load (VL) among HIV-infected pregnant and postpartum women on ART in Cape Town, South Africa. This is the first reported use of this scale in a non-English speaking setting and it achieved good psychometric characteristics (Cronbach α = 0.79). Among 452 women included in the analysis, only 12 % reported perfect adherence on the self-report scale, while 92 % had a VL <1000 copies/mL. Having a raised VL was consistently associated with lower median adherence scores and the area under the curve for the scale was 0.599, 0.656 and 0.642 using a VL cut-off of ≥50, ≥1000 and ≥10000 copies/mL, respectively. This simple self-report adherence scale shows potential as a first-stage adherence screener in this setting. Maternal adherence monitoring in low resource settings requires attention in the era of universal ART, and the value of this simple adherence scale in routine ART care settings warrants further investigation. PMID:27278548

  11. Synthesis and characterization of high-T(c) screen-printed Y-Ba-Cu-O films on alumina

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Simons, Rainee N.; Farrell, D. E.

    1988-01-01

    Thick films of YBa2Cu3O(sub 7-x) have been deposited on highly polished alumina substrates by the screen printing technique. To optimize the post-printing heat treatment, the films were baked at various temperatures for different lengths of time and oxygen-annealed at a lower temperature. The resulting films were characterized by electrical resistivity measurements, X-ray diffraction, and optical and scanning electron microscopy. Properties of the films were found to be highly sensitive to the post-printing thermal treatment. Films baked for 15 min at 1000 C in oxygen were hard, adherent, near single phase, and superconducting with T(sub c) (onset) approx 96 KK, T(sub c) (zero) approx 66 K and Delta T sub c (10 to 90 percent) approx 10 K.

  12. Corrosion resistance characterization of porous alumina membrane supports

    SciTech Connect

    Dong Yingchao; Lin Bin; Zhou Jianer; Zhang Xiaozhen; Ling Yihan; Liu Xingqin; Meng Guangyao; Hampshire, Stuart

    2011-04-15

    Tubular porous alumina ceramic membrane supports were fabricated by an extrusion-drying-sintering process and then characterized in detail in terms of corrosion resistance in both H{sub 2}SO{sub 4} and NaOH aqueous solutions. Variations in the properties of the alumina supports such as mass loss percent, mechanical strength, open porosity and pore size distribution were studied before and after corrosion under different conditions. In addition, the microstructures were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction before and after corrosion. The fabricated porous alumina supports offer possibilities for some potential applications as micro-filtration or ultra-filtration membrane supports, as well as in the pre-treatment of strongly acidic industrial waste-liquids. - Research highlights: {yields} Porous alumina membrane supports fabricated by extrusion-drying-sintering process. {yields} Corrosion resistance in 20 wt.% H{sub 2}SO{sub 4} and 1, 5, 10 wt.% NaOH aqueous solutions. {yields} Rapid mass loss and loss of flexural strength occurred in hot NaOH solution. {yields} Resistant to strong acid corrosion with low mass loss, low flexural strength loss. {yields} Porous alumina supports have potential for treatment of strong acid waste liquids.

  13. Enriched fluoride sorption using alumina/chitosan composite.

    PubMed

    Viswanathan, Natrayasamy; Meenakshi, S

    2010-06-15

    Alumina possesses an appreciable defluoridation capacity (DC) of 1566 mg F(-)/kg. In order to improve its DC, it is aimed to prepare alumina polymeric composites using the chitosan. Alumina/chitosan (AlCs) composite was prepared by incorporating alumina particles in the chitosan polymeric matrix, which can be made into any desired form viz., beads, candles and membranes. AlCs composite displayed a maximum DC of 3809 mg F(-)/kg than the alumina and chitosan (52 mg F(-)/kg). The fluoride removal studies were carried out in batch mode to optimize the equilibrium parameters viz., contact time, pH, co-anions and temperature. The equilibrium data was fitted with Freundlich and Langmuir isotherms to find the best fit for the sorption process. The calculated values of thermodynamic parameters indicate the nature of sorption. The surface characterisation of the sorbent was performed by FTIR, AFM and SEM with EDAX analysis. A possible mechanism of fluoride sorption by AlCs composite has been proposed. Suitability of AlCs composite at field conditions was tested with a field sample taken from a nearby fluoride-endemic village. This work provides a potential platform for the development of defluoridation technology.

  14. Biocompatibility of atomic layer-deposited alumina thin films.

    PubMed

    Finch, Dudley S; Oreskovic, Tammy; Ramadurai, Krishna; Herrmann, Cari F; George, Steven M; Mahajan, Roop L

    2008-10-01

    Presented in this paper is a study of the biocompatibility of an atomic layer-deposited (ALD) alumina (Al2O3) thin film and an ALD hydrophobic coating on standard glass cover slips. The pure ALD alumina coating exhibited a water contact angle of 55 degrees +/- 5 degrees attributed, in part, to a high concentration of -OH groups on the surface. In contrast, the hydrophobic coating (tridecafluoro-1,1,2,2-tetrahydro-octyl-methyl-bis(dimethylamino)silane) had a water contact angle of 108 degrees +/- 2 degrees. Observations using differential interference contrast microscopy on human coronary artery smooth muscle cells showed normal cell proliferation on both the ALD alumina and hydrophobic coatings when compared to cells grown on control substrates. These observations suggested good biocompatibility over a period of 7 days in vitro. Using a colorimetric assay technique to assess cell viability, the cellular response between the three substrates can be differentiated to show that the ALD alumina coating is more biocompatible and that the hydrophobic coating is less biocompatible when compared to the control. These results suggest that patterning a substrate with hydrophilic and hydrophobic groups can control cell growth. This patterning can further enhance the known advantages of ALD alumina, such as conformality and excellent dielectric properties for bio-micro electro mechanical systems (Bio-MEMS) in sensors, actuators, and microfluidics devices.

  15. The nature of hydrogen in γ-alumina

    SciTech Connect

    Li, Yunguo Lousada, Cláudio M. Korzhavyi, Pavel A.

    2014-05-28

    Gibbs free energy models are derived from the calculated electronic and phonon structure of two possible models of γ-alumina, a defective spinel phase and a hydrogenated spinel phase. The intrinsic vacancies and hydrogen in the two structural models give rise to a considerable configurational (residual) entropy and significantly contribute to thermodynamic stability and physical-chemical properties of γ-alumina, which was neglected in previous studies but considered in this work. The electronic densities of states, calculated using a hybrid functional for the two structural models of γ-alumina, are presented. The dynamic stability of the two phases is confirmed by full-spectrum phonon calculations. The two phases share many similarities in their electronic structure, but can be distinguished by their vibrational spectra and specific heat. The defective spinel is found to be the ground state of γ-alumina, while the hydrogenated spinel to be a metastable phase. However, dehydration of the metastable phase into the ground state is expected to be slow due to the low diffusion rate of H, which leaves hydrogen as a locked-in impurity in γ-alumina.

  16. Effect of humic acid on sorption of technetium by alumina.

    PubMed

    Kumar, S; Rawat, N; Kar, A S; Tomar, B S; Manchanda, V K

    2011-09-15

    Sorption of technetium by alumina has been studied in absence as well as in presence of humic acid using (95)Tc(m) as a tracer. Measurements were carried out at fixed ionic strength (0.1M NaClO(4)) under varying pH (3-10) as well as redox (aerobic and reducing anaerobic) conditions. Under aerobic conditions, negligible sorption of technetium was observed onto alumina both in absence and in presence of humic acid. However, under reducing conditions (simulated with [Sn(II)] = 10(-6)M), presence of humic acid enhanced the sorption of technetium in the low pH region significantly and decreased at higher pH with respect to that in absence of humic acid. Linear additive as well as surface complexation modeling of Tc(IV) sorption in presence of humic acid indicated the predominant role of sorbed humic acid in deciding technetium sorption onto alumina.

  17. The surface reaction kinetics of salicylate on alumina

    SciTech Connect

    Wang, Z.; Ainsworth, C.C.; Friedrich, D.M.; Joly, A.G.; Gassman, P.L.

    1997-12-31

    The kinetics of reaction of salicylate with colloidal alumina in aqueous suspension and with Al(III) in homogeneous aqueous solution were studied by stopped-flow laser fluorescence spectroscopy. The emission spectra confirmed the formation of both monodentate complexes and more stable bidentate chelates. Temporal evolution of the spectra indicated that the reaction was fast (within first few minutes) for both the homogeneous and heterogeneous reactions but slowed down afterwards for the latter. Reactions completed within 10 minutes in homogeneous phase at pH 3.3 but took more than 12 hours in alumina suspension. Analysis of the fluorescence intensity within first four minutes showed that in homogeneous phase the reaction followed a single pseudo-first-order kinetics. In alumina suspension log plots were nonlinear and characteristic of multiple heterogeneous reaction paths. The kinetics are interpreted in terms of the simultaneous formation of multiple species as well as subsequent conversion between species.

  18. Alumina composites for oxide/oxide fibrous monoliths

    SciTech Connect

    Cruse, T. A.; Polzin, B. J.; Picciolo, J. J.; Singh, D.; Tsaliagos, R. N.; Goretta, K. C.

    2000-03-01

    Most work on ceramic fibrous monoliths (FMs) has focused on the Si{sub 3}N{sub 4}/BN system. In an effort to develop oxidation-resistant FMs, several oxide systems have recently been examined. Zirconia-toughened alumina and alumina/mullite appear to be good candidates for the cell phase of FMs. These composites offer higher strength and toughness than pure alumina and good high-temperature stability. By combining these oxides, possibly with a weaker high-temperature oxide as the cell-boundary phase, it should be possible to product a strong, resilient FM that exhibits graceful failure. Several material combinations have been examined. Results on FM fabrication and microstructural development are presented.

  19. Origin of High-Alumina Basalt, Andesite, and Dacite Magmas.

    PubMed

    Hamilton, W

    1964-10-30

    The typical volcanic rocks of most island arcs and eugeosynclines, and of some continental environments, are basalt, andesite, and dacite, of high alumina content. The high-alumina basalt differs from tholeiitic basalt primarily in having a greater content of the components of calcic plagioclase. Laboratory data indicate that in the upper mantle, below the level at which the basaltic component of mantle rock is transformed by pressure to eclogite or pyroxenite, the entire basaltic portion probably is melted within a narrow temperature range, but that above the level of that transformation plagioclase is melted selectively before pyroxene over a wide temperature range. The broad spectrum of high-alumina magmas may represent widely varying degrees of partial melting above the transformation level, whereas narrow-spectrum tholeiite magma may represent more complete melting beneath it.

  20. Plastic deformation and sintering of alumina under high pressure

    SciTech Connect

    Liu, Fangming; Liu, Pingping; Wang, Haikuo; Xu, Chao; Yin, Shuai; Yin, Wenwen; Li, Yong; He, Duanwei

    2013-12-21

    Plastic deformation of alumina (Al{sub 2}O{sub 3}) under high pressure was investigated by observing the shape changes of spherical particles, and the near fully dense transparent bulks were prepared at around 5.5 GPa and 900 °C. Through analyzing the deformation features, densities, and residual micro-strain of the Al{sub 2}O{sub 3} compacts prepared under high pressures and temperatures (2.0–5.5 GPa and 600–1200 °C), the effects of plastic deformation on the sintering behavior of alumina have been demonstrated. Under compression, the microscopic deviatoric stress caused by grain-to-grain contact could initiate the plastic deformation of individual particles, eliminate pores of the polycrystalline samples, and enhance the local atomic diffusion at the grain boundaries, thus produced transparent alumina bulks.

  1. Molecular dynamics studies of interfacial water at the alumina surface.

    SciTech Connect

    Argyris, Dr. Dimitrios; Ho, Thomas; Cole, David

    2011-01-01

    Interfacial water properties at the alumina surface were investigated via all-atom equilibrium molecular dynamics simulations at ambient temperature. Al-terminated and OH-terminated alumina surfaces were considered to assess the structural and dynamic behavior of the first few hydration layers in contact with the substrates. Density profiles suggest water layering up to {approx}10 {angstrom} from the solid substrate. Planar density distribution data indicate that water molecules in the first interfacial layer are organized in well-defined patterns dictated by the atomic terminations of the alumina surface. Interfacial water exhibits preferential orientation and delayed dynamics compared to bulk water. Water exhibits bulk-like behavior at distances greater than {approx}10 {angstrom} from the substrate. The formation of an extended hydrogen bond network within the first few hydration layers illustrates the significance of water?water interactions on the structural properties at the interface.

  2. Fabrication of alumina films with laminated structures by ac anodization

    PubMed Central

    Segawa, Hiroyo; Okano, Hironaga; Wada, Kenji; Inoue, Satoru

    2014-01-01

    Anodization techniques by alternating current (ac) are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50–200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials. PMID:27877636

  3. Modifying alumina red mud to support a revegetation cover

    NASA Astrophysics Data System (ADS)

    Xenidis, A.; Harokopou, A. D.; Mylona, E.; Brofas, G.

    2005-02-01

    Alumina red mud, a fine-textured, iron-rich, alkaline residue, is the major waste product of bauxite digestion with caustic soda to remove alumina. The high alkalinity and salinity as well as the poor nutrient status are considered to be the major constraints of red mud revegetation. This research was conducted to evaluate the ameliorating effect of gypsum, sewage sludge, ferrous sulfate, ammonium sulfate, ammonium nitrate, and calcium phosphate on alumina red mud. The effectiveness of the mixtures was evaluated by applying extraction tests and performing experiments using six plant species. Gypsum amendment significantly reduced the pH, electrical conductivity, and sodium and aluminum content of red mud. Sewage sludge application had an extended effect in improving both the soil structure and the nutrient status of the gypsum-amended red mud. Together with the gypsum and sewage sludge, calcium phosphate application into red mud enhanced plant growth and gave the most promising results.

  4. Characteristics of alumina particles in dispersion-strengthened copper alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Xue-hui; Li, Xiao-xian

    2014-11-01

    Two types of alumina dispersion-strengthened copper (ADSC) alloys were fabricated by a novel in-situ reactive synthesis (IRS) and a traditional internal oxidation (IO) process. The features of alumina dispersoids in these ADSC alloys were investigated by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. It is found that nano-sized γ-Al2O3 particles of approximately 10 nm in diameter are homogeneously distributed in the IRS-ADSC composites. Meanwhile, larger-sized, mixed crystal structure alumina with rod-shaped morphology is embedded in the IO-ADSC alloy. The IRS-ADSC composites can obtain better mechanical and physical properties than the IO-ADSC composites; the tensile strength of the IRS-ADSC alloy can reach 570 MPa at room temperature, its electrical conductivity is 85% IACS, and the Rockwell hardness can reach 86 HRB.

  5. Medication Adherence in the General Population

    PubMed Central

    Glombiewski, Julia A.; Nestoriuc, Yvonne; Rief, Winfried; Glaesmer, Heide; Braehler, Elmar

    2012-01-01

    Background Adherence to medication is low in specific populations who need chronic medication. However, adherence to medication is also of interest in a more general fashion, independent of specific populations or side effects of particular drugs. If clinicians and researchers expect patients to show close to full adherence, it is relevant to know how likely the achievement of this goal is. Population based rates can provide an estimate of efforts needed to achieve near complete adherence in patient populations. The objective of the study was to collect normative data for medication nonadherence in the general population. Methods and Findings We assessed 2,512 persons (a representative sample of German population). Adherence was measured by Rief Adherence Index. We also assessed current medication intake and side effects. We found that at least 33% of Germans repeatedly fail to follow their doctor's recommendations regarding pharmacological treatments and only 25% of Germans describe themselves as fully adherent. Nonadherence to medication occurs more often in younger patients with higher socioeconomic status taking short-term medications than in older patients with chronic conditions. Experience with medication side effects was the most prominent predictor of nonadherence. Conclusions The major strengths of our study are a representative sample and a novel approach to assess adherence. Nonadherece seems to be commonplace in the general population. Therefore adherence cannot be expected per se but needs special efforts on behalf of prescribers and public health initiatives. Nonadherence to medication should not only be considered as a drug-specific behaviour problem, but as a behaviour pattern that is independent of the prescribed medication. PMID:23272064

  6. Medication Adherence Interventions That Target Subjects with Adherence Problems: Systematic Review and Meta-analysis

    PubMed Central

    Conn, Vicki S.; Ruppar, Todd M.; Enriquez, Maithe; Cooper, Pam

    2015-01-01

    Background Inadequate medication adherence is a pervasive, under-recognized cause of poor health outcomes. Many intervention trials designed to improve medication adherence have targeted adults with adherence problems. No previous reviews have synthesized the effectiveness of medication adherence interventions focused on subjects with medication adherence difficulties. Objective This systematic review and meta-analysis synthesized findings from medication adherence intervention studies conducted among adults with medication adherence difficulties. Methods Primary research studies were eligible for inclusion if they tested an intervention designed to increase medication adherence among adults with documented adherence difficulties and reported medication adherence behavior outcomes. Comprehensive search strategies of 13 computerized databases, author and ancestry searches, and hand searches of 57 journals were used to locate eligible primary research. Participant demographics, intervention characteristics, and methodological features were reliably coded from reports along with medication adherence outcomes. Effect sizes for outcomes were calculated as standardized mean differences, and random effects models were used to estimate overall mean effects. Exploratory dichotomous and continuous variable moderator analyses were employed to examine potential associations between medication adherence effect size and sample, intervention, and methodological characteristics. Results Data were extracted from 53 reports of studies involving 8,243 individual primary study participants. The overall standardized mean difference effect size for treatment vs. control subjects was 0.301. For treatment pre- vs. post-intervention comparisons, the overall effect size was 0.533. Significantly larger effect sizes were associated with interventions incorporating prompts to take medications than interventions lacking medication prompts (0.497 vs. 0.234). Larger effect sizes were also found

  7. Acoustic response from adherent targeted contrast agents

    PubMed Central

    Zhao, Shukui; Kruse, Dustin E.; Ferrara, Katherine W.; Dayton, Paul A.

    2006-01-01

    In ultrasonic molecular imaging, encapsulated micron-sized gas bubbles are tethered to a blood vessel wall by targeting ligands. A challenging problem is to detect the echoes from adherent microbubbles and distinguish them from echoes from non-adherent agents and tissue. Echoes from adherent contrast agents are observed to include a high amplitude at the fundamental frequency, and significantly different spectral shape compared with free agents (p < 0.0003). Mechanisms for the observed acoustical difference and potential techniques to utilize these differences for molecular imaging are proposed. PMID:17225437

  8. Factors contributing to the breakdown of sodium beta-alumina

    SciTech Connect

    Buechele, A.C.

    1982-05-01

    Clarification of the breakdown process occurring during charge transfer in sodium beta alumina solid electrolytes was derived from: (1) studying the effects of molten sodium contact at 350/sup 0/C on single crystal sodium beta alumina and polycrystalline sodium beta alumina; (2) determination of critical current density by monitoring acoustic emissions accompanying crack growth in sodium/sodium beta alumina/sodium cells subjected to linear current ramping at 1 mA cm/sup -2/ sec/sup -1/; (3) failure analysis conducted on cycled electrolytes, some from commercial sodium/sulfur cells, which had been subjected to up to 703 Ahr cm/sup -2/ of charge transfer. Gray coloration developing in beta aluminas in contact with molten sodium was found to be a consequence of formation, through reduction by sodium, of oxygen vacancies charge compensated by electrons. Electronic conductivity of the electrolyte increases as a result. No second phase formation was detected. Colored electrolytes from sodium/sulfur cells show evidence of a newly recognized degradation mechanism in which fracture occurs when sodium is reduced and deposited internally under pressure as metal in regions where an electronic conductivity gradient exists. Heating colored beta aluminas in air produces reoxidation and bleaching. Kinetics and other properties of the coloration and bleaching processes were determined. Critical current density was found to bear an inverse relation to average electrolyte grain size. Evidence was found in the cycled electrolytes for a slow crack growth mechanism and a progressive mode of degradation advancing from the sulfur electrode interface. Implications of the findings for the construction and operation of sodium/sulfur battery systems are discussed.

  9. Effects of atmospheres on bonding characteristics of silver and alumina

    SciTech Connect

    Kim, Jin Yong; Engelhard, Mark H.; Choi, Jung-Pyung; Weil, K. Scott

    2008-03-12

    Joints prepared using a silver-copper oxide based reactive air brazing (RAB) technique is known to experience a significant decrease in joint strength when exposed in a reducing atmosphere at high temperature. To investigate the effects of atmospheres on the bonding characteristics of ceramic joints brazed with Ag-CuO braze filler metals, alumina joints prepared using a series of Ag-CuO compositions were exposed to a reducing atmosphere in hydrogen and also reoxidized in air at 800°C. All the brazed joints exposed to hydrogen revealed significant reduction in flexural strength and exhibited debonding of the interface between the braze filler and the alumina substrate. In the case of the joints brazed with a braze filler containing a high copper content of 8 mol%, the formation of interfacial porosity caused by the reduction of interfacial oxide phases led to an extremely weak interface, which was not recovered after subsequent reoxidation in air at 800°C. However, no significant microstructural change or interfacial porosity formation was observed in the braze filler metals containing no or low copper contents, and the interface remained intact even though interfacial strength was weak. Subsequent reoxidation of the joints with these filler materials resulted in the recovery of interfacial strength and flexural strength. This result clearly indicates that the bonding characteristics of the silver/alumina interface are by and large influenced by atmospheres of high temperature exposure. XPS analysis conducted on the in-situ¬ fractured surfaces of as-brazed and hydrogen-treated samples prepared using a braze filler with 2 mol% Cu indicated that oxygen in the silver matrix plays a critical role in bond strength between silver and alumina. The sample exposed in inert atmosphere also revealed low flexural strength and debonding of the silver/alumina interface, confirming the role of oxygen on the bond strength between silver and alumina.

  10. Quantifying Alumina Nanoparticle Dispersion in Hybrid Carbon Fiber Composites Using Photoluminescent Spectroscopy.

    PubMed

    Hanhan, Imad; Selimov, Alex; Carolan, Declan; Taylor, Ambrose C; Raghavan, Seetha

    2017-02-01

    Composites modified with nanoparticles are of interest to many researchers due to the large surface-area-to-volume ratio of nano-scale fillers. One challenge with nanoscale materials that has received significant attention is the dispersion of nanoparticles in a matrix material. A random distribution of particles often ensures good material properties, especially as it relates to the thermal and mechanical performance of composites. Typical methods to quantify particle dispersion in a matrix material include optical, scanning electron, and transmission electron microscopy. These utilize images and a variety of analysis methods to describe particle dispersion. This work describes how photoluminescent spectroscopy can serve as an additional technique capable of quickly and comprehensively quantifying particle dispersion of photoluminescent particles in a hybrid composite. High resolution 2D photoluminescent maps were conducted on the front and back surfaces of a hybrid carbon fiber reinforced polymer containing varying contents of alumina nanoparticles. The photoluminescent maps were analyzed for the intensity of the alumina R1 fluorescence peak, and therefore yielded alumina particle dispersion based on changes in intensity from the embedded nanoparticles. A method for quantifying particle sedimentation is also proposed that compares the photoluminescent data of the front and back surfaces of each hybrid composite and assigns a single numerical value to the degree of sedimentation in each specimen. The methods described in this work have the potential to aid in the manufacturing processes of hybrid composites by providing on-site quality control options, capable of quickly and noninvasively providing feedback on nanoparticle dispersion and sedimentation.

  11. Sex Differences in Barriers to Antihypertensive Medication Adherence: Findings From the Cohort Study of Medication Adherence Among Older Adults (CoSMO)

    PubMed Central

    Holt, Elizabeth; Joyce, Cara; Dornelles, Adriana; Morisky, Donald; Webber, Larry S.; Muntner, Paul; Krousel-Wood, Marie

    2013-01-01

    Objectives We assessed whether socio-demographic, clinical, health care system, psychosocial, and behavioral factors are differentially associated with low antihypertensive medication adherence scores among older men and women. Design / Setting A cross-sectional analysis using baseline data from the Cohort Study of Medication Adherence in Older Adults (CoSMO, n=2,194). Measurements Low antihypertensive medication adherence was defined as a score <6 on the 8-item Morisky Medication Adherence Scale. Risk factors for low adherence were collected using telephone surveys and administrative databases. Results The prevalence of low medication adherence scores did not differ according to sex (15.0% in women and 13.1% in men p=0.208). In sex-specific multivariable models, having issues with medication cost and practicing fewer lifestyle modifications for blood pressure control were associated with low adherence scores among both men and women. Factors associated with low adherence scores in men but not women included reduced sexual functioning (OR = 2.03; 95% CI: 1.31, 3.16 for men and OR = 1.28; 95% CI: 0.90, 1.82 for women), and BMI ≥25 (OR = 3.23; 95% CI: 1.59, 6.59 for men and 1.23; 95% CI: 0.82, 1.85 for women). Factors associated with low adherence scores in women but not men included dissatisfaction with communication with their healthcare provider (OR = 1.75; 95% CI: 1.16, 2.65 for women and OR =1.16 95% CI: 0.57, 2.34 for men) and depressive symptoms (OR = 2.29; 95% CI: 1.55, 3.38 for women and OR = 0.93; 95% CI: 0.48, 1.80 for men). Conclusion Factors associated with low antihypertensive medication adherence scores differed according to sex. Interventions designed to improve adherence in older adults should be tailored to account for the sex of the target population. PMID:23528003

  12. Influence of the First Consultation on Adherence to Antiretroviral Therapy for HIV-infected Patients

    PubMed Central

    Peyre, Marion; Gauchet, Aurélie; Roustit, Matthieu; Leclercq, Pascale; Epaulard, Olivier

    2016-01-01

    Background: Physician attitude influences the way patients cope with diagnosis and therapy in chronic severe diseases such as cancer. Previous studies showed that such an effect exists in HIV care; it is likely that it begins with the first contact with a physician. Objective: We aimed to explore in HIV-infected persons their perception of the first consultation they had with an HIV specialist (PFC-H), and whether this perception correlates with adherence to antiretroviral therapy. Method: The study was conducted in Grenoble University Hospital, France, a tertiary care center. Every antiretroviral-experienced patient was asked to freely complete a self-reported, anonymous questionnaire concerning retrospective PFC-H, present adherence (Morisky scale), and present perceptions and beliefs about medicine (BMQ scale). Results: One hundred and fifty-one questionnaires were available for evaluation. PFC-H score and adherence were correlated, independently from age, gender, and numbers of pill(s) and of pill intake(s) per day. BMQ score also correlated with adherence; structural equation analysis suggested that the effect of PFC-H on adherence is mediated by positive beliefs. Conclusion: These results suggest that for HIV-infected persons, the perceptions remaining from the first consultation with an HIV specialist physician influence important issues such as adherence and perception about medicine. Physicians must be aware of this potentially long-lasting effect. PMID:27708747

  13. Current Noise in Sodium Beta Alumina Ceramics and Single Crystals.

    DTIC Science & Technology

    1986-08-01

    AD-Ai7O 412 CURRENT NOISE IN SODIUM BETA ALUMINA CERAMICS AIND t/l SINGLE CRYSTALS(U) UTAH UNIV SALT LAKE CITY DEPT OF PHYSICS J J BROPHY’ 81 AUG 86...ZIP C-0- UNIVERSITY OF UTAH UNIVERSITY OF NEW MEXICO SALT LAKE CITY, UTAH 84112 Bandelier Hall West Albuquerque, NM 87131 go NAME OF FUNDING...bloeS nIumbe Conductivity fluctuations and contact noise observed in ceramic and single crystal silver 811 alumina are very pilar to those in sodium 8

  14. Atomistic force field for alumina fit to density functional theory

    SciTech Connect

    Sarsam, Joanne; Finnis, Michael W.; Tangney, Paul

    2013-11-28

    We present a force field for bulk alumina (Al{sub 2}O{sub 3}), which has been parametrized by fitting the energies, forces, and stresses of a large database of reference configurations to those calculated with density functional theory (DFT). We use a functional form that is simpler and computationally more efficient than some existing models of alumina parametrized by a similar technique. Nevertheless, we demonstrate an accuracy of our potential that is comparable to those existing models and to DFT. We present calculations of crystal structures and energies, elastic constants, phonon spectra, thermal expansion, and point defect formation energies.

  15. Fabrication and characterization of alumina tube by thermal spray forming

    NASA Astrophysics Data System (ADS)

    Mohammed, M. A.; Zaidan, Sh. A.; Smich, H. E.

    2017-02-01

    In the present study spray forming of alumina tube with a wall thickness of 0.4-0.6 mm and the diameter of 38-62 mm on graphite substrate with two different sizes of alumina feedstock powders was used for flame spraying to form matrix of Al2O3 structures which have been fabricated. A detailed characterization of the spray-formed Al2O3 structure has been performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), (AFM) and Micro Hardness measurements. This study proves that a variety of structured materials and their combinations can be fabricated to near net shapes.

  16. The influence of aluminum grain size on alumina nanoporous structure

    SciTech Connect

    Feil, A. F.; Costa, M. V. da; Amaral, L.; Teixeira, S. R.; Migowski, P.; Dupont, J.; Machado, G.; Peripolli, S. B.

    2010-01-15

    An approach to control the interpore distances and nanopore diameters of 150-nm-thick thin aluminum films is reported here. The Al thin films were grown by sputtering on p-type silicon substrate and anodized with a conventional anodization process in a phosphoric acid solution. It was found that interpore distance and pore diameter are related to the aluminum grain size and can be controlled by annealing. The grain contours limit the sizes of alumina cells. This mechanism is valid for grain sizes supporting only one alumina cell and consequently only one pore.

  17. Mechanical properties of tricalcium phosphate-alumina composites

    NASA Astrophysics Data System (ADS)

    Sakka, S.; Ben Ayed, F.; Bouaziz, J.

    2012-02-01

    Tricalcium phosphate and alumina powder were mixed in order to elaborate biphasic ceramics composites. This study deals to produce bioceramics composites sintered at various temperatures for differents times. The characterization of samples, before and after the sintering process was investigated, using X-Ray diffraction, scanning electronic microscopy, 31P and 27Al nuclear magnetic resonance and differential thermal analysis. Mechanical properties of biphasic composites were studied using Brazilian test. The tricalcium phosphate - 75 wt% alumina composites mechanical resistance increased with sintered temperature. The mechanical resistance reach it's optimum value (8.6 MPa) at 1550°C for two hours.

  18. Study on surface properties of gamma-alumina catalytic membrane

    SciTech Connect

    Mengchenu Lu; Guoxing Xiong; Bauser, H.

    1994-12-31

    In recent years, preparation and separation applications of gamma-alumina membranes have been extensively studied. In catalysis research field, this membrane can be used not only as a separating medium but also as a catalyst or catalyst support. In this paper, a gamma-alumina catalytic membrane was prepared by a sol-gel technique, then special attention was paid to its surface properties related to catalysis, its surface acidity, hydroxyl, microstructure and pore properties was studied by IR with pyridine adsorption, XRD and N{sub 2} adsorption at low temperature, 1-butanol dehydration as a probe reaction was used to study its reaction property.

  19. Interplay between Oral Hypoglycemic Medication Adherence and Quality of Life among Elderly Type 2 Diabetes Mellitus Patients

    PubMed Central

    Manan, Mohamed Mansor; Husin, Akhma Radzuanna; Alkhoshaiban, Ali Saleh; Al-Worafi, Yaser Mohammed Ali

    2014-01-01

    Background: Adherence to medications is an important factor that contributes to therapeutic success. With the current increase in the elderly population, information relating to adherence to treatment and quality of life (QoL) of diabetic elderly patients will help the healthcare provider to improve their treatment. Thus, this study aims to determine the factors affecting adherence to medications and the consequence of non adherence to QoL. Materials and Methods: This was a cross-sectional study using validated Morisky Medication Adherence Scale (MMAS) Questionnaire. This study was conducted to assess the level of adherence on oral hypoglycemic medications (OHM) and quality of life of the Type 2 diabetes mellitus (T2DM) elderly patients in an urban health centre in Malaysia. A retrospective medication record review was also conducted to collect and confirm data on patients’ demographics, diagnosis, treatments, and outcomes. Results: One hundred and seventy nine patients were recruited in this study. Median adherence score was 7.75 (IQR 6.50- 8.00). Good adherer was observed in 48.00% of the participants. A Chi-square test indicated significant correlation between adherence and HbA1c (p= 0.010). The mean elderly diabetes mellitus Problem Areas in Diabetes (PAID) score was 6.30 ±SD 8.50. A significant inversed association was observed between PAID score and the level of adherence (r = - 0.175, p< 0.05). A highly significant difference in the low adherence group (p = 0.002). PAID score significantly correlated with age (years), female gender and HbA1c (p <0.05). A negative association between HbA1c levels and adherence was identified where a 1% increase in HbA1c was associated with a 30% decrease in the likelihood of being adherent. Conclusion: A medication adherence rate of 48% was obtained among elderly T2DM patients treated in the primary care clinic. This study showed that HbA1c is a relevant tool to assess patient glycemic control and adherence

  20. The association between Self-Reported Medication Adherence scores and systolic blood pressure control: a SPRINT baseline data study.

    PubMed

    Haley, William E; Gilbert, Olivia N; Riley, Robert F; Newman, Jill C; Roumie, Christianne L; Whittle, Jeffrey; Kronish, Ian M; Tamariz, Leonardo; Wiggers, Alan; Morisky, Donald E; Conroy, Molly B; Kovalik, Eugene; Kressin, Nancy R; Muntner, Paul; Goff, David C

    2016-11-01

    We examined baseline data from the Systolic Blood Pressure Intervention Trial (SPRINT) to investigate whether medication adherence, measured by the 8-item Morisky Medication Adherence Scale (MMAS-8), was associated with systolic blood pressure (SBP) and whether MMAS-8 score and number of antihypertensive medications interacted in influencing SBP. A total of 8435 SPRINT participants were included: 21.2% had low adherence (MMAS-8: <6); 40.0% had medium adherence (6 to <8); and 38.8% had high adherence (8). SBP was <140 mm Hg in 54.6%; 140-160 mm Hg in 36.6%; and >160 mm Hg in 8.8%. In multivariable regression, medium vs. low adherence weakly associated with lower SBP (odds ratio: 1.17; confidence interval: 1.04, 1.31). SPRINT eligibility criteria should be considered when interpreting results. Efforts to understand and enhance adherence are crucial to improve population health, and using self-report instruments might be considered for predicting treatment adherence and response in future efficacy trials and for identifying patients for adherence support in clinical practice.

  1. Preliminary validity of the barriers to treatment adherence questionnaire in fibromyalgia: combining quantitative and focus group data.

    PubMed

    Dobkin, Patricia L; De Civita, Mirella; Bernatsky, Sasha; Filipski, Marta; Sita, Aurelio; Baron, Murray

    2009-10-01

    The goals of this study were to (1) provide preliminary reliability and validity of the Barriers to Treatment Adherence Questionnaire, developed for patients with fibromyalgia, and (2) examine barriers to adherence and general adherence to multimodal treatment during a 3-mo. period. A secondary goal was to explore in a focus discussion group format patients' perceptions of the adherence process and ways of managing the treatment program. 39 fibromyalgia patients were followed while participating in a combined outpatient program of physiotherapy, occupational therapy, nursing, and cognitive behavioral therapy. The Barriers to Treatment Adherence Questionnaire demonstrated good reliability. Construct validity of the Barriers to Treatment Adherence Questionnaire was supported through significant positive correlations with the General Adherence Scale at Months 1 and 3. In addition, a significant change was observed in scores on the Barriers to Treatment Adherence Questionnaire for the physiotherapy component of treatment, with scores decreasing between Months 2 and 3. Addressing barriers to improve adherence may maximize the benefit of treatment programs.

  2. Association between addressing antiseizure drug side effects and patient-reported medication adherence in epilepsy

    PubMed Central

    Moura, Lidia M V R; Carneiro, Thiago S; Cole, Andrew J; Hsu, John; Vickrey, Barbara G; Hoch, Daniel B

    2016-01-01

    Background and aim Adherence to treatment is a critical component of epilepsy management. This study examines whether addressing antiepileptic drug (AED) side effects at every visit is associated with increased patient-reported medication adherence. Patients and methods This study identified 243 adults with epilepsy who were seen at two academic outpatient neurology settings and had at least two visits over a 3-year period. Demographic and clinical characteristics were abstracted. Evidence that AED side effects were addressed was measured through 1) phone interview (patient-reported) and 2) medical records abstraction (physician-documented). Medication adherence was assessed using the validated Morisky Medication Adherence Scale-4. Complete adherence was determined as answering “no” to all questions. Results Sixty-two (25%) patients completed the interviews. Participants and nonparticipants were comparable with respect to demographic and clinical characteristics; however, a smaller proportion of participants had a history of drug-resistant epilepsy than nonparticipants (17.7% vs 30.9%, P=0.04). Among the participants, evidence that AED side effects were addressed was present in 48 (77%) medical records and reported by 51 (82%) patients. Twenty-eight (45%) patients reported complete medication adherence. The most common reason for incomplete adherence was missed medication due to forgetfulness (n=31, 91%). There was no association between addressing AED side effects (neither physician-documented nor patient-reported) and complete medication adherence (P=0.22 and 0.20). Discussion and conclusion Among patients with epilepsy, addressing medication side effects at every visit does not appear to increase patient-reported medication adherence. PMID:27826186

  3. Infection Control Practice in the Operating Room: Staff Adherence to Existing Policies in a Developing Country

    PubMed Central

    Cawich, Shamir O; Tennant, Ingrid A; McGaw, Clarence D; Harding, Hyacinth; Walters, Christine A; Crandon, Ivor W

    2013-01-01

    Context: Infection control interventions are important for containing surgery-related infections. For this reason, the modern operating room (OR) should have well-developed infection control policies. The efficacy of these policies depends on how well the OR staff adhere to them. There is a lack of available data documenting adherence to infection control policies. Objective: To evaluate OR staff adherence to existing infection control policies in Jamaica. Methods: We administered a questionnaire to all OR staff to assess their training, knowledge of local infection control protocols, and practice with regard to 8 randomly selected guidelines. Adherence to each guideline was rated with fixed-choice items on a 4-point Likert scale. The sum of points determined the adherence score. Two respondent groups were defined: adherent (score > 26) and nonadherent (score ≤ 26). We evaluated the relationship between respondent group and age, sex, occupational rank, and time since completion of basic medical training. We used χ2 and Fisher exact tests to assess associations and t tests to compare means between variables of interest. Results: The sample comprised 132 participants (90 physicians and 42 nurses) with a mean age of 36 (standard deviation ± 9.5) years. Overall, 40.1% were adherent to existing protocols. There was no significant association between the distribution of adherence scores and sex (p = 0.319), time since completion of basic training (p = 0.595), occupational rank (p = 0.461), or age (p = 0.949). Overall, 19% felt their knowledge of infection control practices was inadequate. Those with working knowledge of infection control practices attained it mostly through informal communication (80.4%) and self-directed research (62.6%). Conclusion: New approaches to the problem of nonadherence to infection control guidelines are needed in the Caribbean. Several unique cultural, financial, and environmental factors influence adherence in this region, in contrast to

  4. Dietary adherence and acceptability of five different diets, including vegan and vegetarian diets, for weight loss: The New DIETs study.

    PubMed

    Moore, Wendy J; McGrievy, Michael E; Turner-McGrievy, Gabrielle M

    2015-12-01

    The goal of the present study was to examine dietary adherence and acceptability among participants from the New DIETs study who were randomized to one of four plant-based diets (vegan, vegetarian, pesco-vegetarian, semi-vegetarian) or an omnivore diet. Primary outcomes at two- and six months included dietary adherence (24-hour dietary recalls), weight loss and changes in animal product intake (mg cholesterol) by adherence status, Three-Factor Eating Questionnaire (TFEQ), Power of Food Scale (PFS), dietary acceptability (Food Acceptability Questionnaire), and impact of diet preference on adherence. No differences were found in dietary adherence or changes in FAQ, TFEQ, or PFS among the groups. At six months, non-adherent vegan and vegetarian participants (n=16) had a significantly greater decrease in cholesterol intake (-190.2 ± 199.2 mg) than non-adherent pesco-vegetarian/semi-vegetarian (n=15, -2.3 ± 200.3 mg, P=0.02) or omnivore participants (n=7, 17.0 ± 36.0, P=0.04). Non-adherent vegan/vegetarian participants lost significantly more weight at six months (-6.0 ± 6.7%) than non-adherent omnivore participants (-0.4 ± 0.6%, P=0.04). Dietary preference had no impact on adherence at six months. Due to equal rates of adherence and acceptability among the diet groups, instructing participants to follow vegan or vegetarian diets may have a greater impact on weight loss and animal product intake than providing instruction in more moderate approaches even among non-adherent participants.

  5. Final report on the application of chaos theory to an alumina sensor for aluminum reduction cells. Inert Electrodes Program

    SciTech Connect

    Williford, R.E.; Windisch, C.F. Jr.

    1992-03-01

    Four chaos-related digital signal analysis (DSA) methods were applied to the analysis of voltage and current signals collected from aluminum electrolysis cells. Two separate data bases were analyzed: bench-scale laboratory experiments and a pilot-scale test. The objective was to assess the feasibility of using these types of data and analysis methods as the basis for a non-intrusive sensor to measure the alumina content in the electrolysis bath. This was the first time chaos theory approaches have been employed to analyze aluminum electrolysis cells.

  6. Medication adherence behaviors of Medicare beneficiaries

    PubMed Central

    Carr-Lopez, Sian M; Shek, Allen; Lastimosa, Janine; Patel, Rajul A; Woelfel, Joseph A; Galal, Suzanne M; Gundersen, Berit

    2014-01-01

    Background Medication adherence is crucial for positive outcomes in the management of chronic conditions. Comprehensive medication consultation can improve medication adherence by addressing intentional and unintentional nonadherence. The Medicare Part D prescription drug benefit has eliminated some cost barriers. We sought to examine variables that impact self-reported medication adherence behaviors in an ambulatory Medicare-beneficiary population and to identify the factors that influence what information is provided during a pharmacist consultation. Methods Medicare beneficiaries who attended health fairs in northern California were offered medication therapy management (MTM) services during which demographic, social, and health information, and responses to survey questions regarding adherence were collected. Beneficiaries were also asked which critical elements of a consultation were typically provided by their community pharmacist. Survey responses were examined as a function of demographic, socioeconomic, and health-related factors. Results Of the 586 beneficiaries who were provided MTM services, 575 (98%) completed the adherence questions. Of responders, 406 (70%) reported taking medications “all of the time”. Of the remaining 169 (30%), the following reasons for nonadherence were provided: 123 (73%) forgetfulness; 18 (11%) side effects; and 17 (10%) the medication was not needed. Lower adherence rates were associated with difficulty paying for medication, presence of a medication-related problem, and certain symptomatic chronic conditions. Of the 532 who completed survey questions regarding the content of a typical pharmacist consultation, the topics included: 378 (71%) medication name and indication; 361 (68%) administration instructions; 307 (58%) side effects; 257 (48%) missed-dose instructions; and 245 (46%) interactions. Subsidy recipients and non-English speakers were significantly less likely to be counseled on drug name, indication, and side

  7. Antiplatelet resistance in outpatients with monitored adherence.

    PubMed

    Walter, Philipp N; Tsakiris, Dimitrios A; Romanens, Michel; Arnet, Isabelle; Hersberger, Kurt E

    2014-01-01

    Antiplatelet resistance with aspirin and clopidogrel has been associated with clinical, cellular and pharmacogenetic factors; and non-adherence has been considered as a major contributor to resistance in outpatients. We aimed at assessing factors to resistance when adherence to the antiplatelet drugs and all other oral solid drugs was controlled for. In a pilot study, we tested arachidonic acid and/or ADP-induced in vitro platelet aggregation of 82 outpatients with chronic aspirin and/or clopidogrel treatment before and after a one-week period of measuring the patient's adherence with the polymedication electronic monitoring system (POEMS). Resistance was found in 20% (aspirin; n = 69) and 25% (clopidogrel; n = 32) of the patients after monitored adherence. Mean platelet aggregation was not (aspirin) or non-significantly (clopidogrel) lowered when compared to baseline. Diabetes mellitus and inflammation were consistently associated with resistance to both drugs, but CYP2C19 polymorphisms could not be confirmed as predictors of clopidogrel response. Electronically compiled multidrug dosing histories allowed the concomitant intake of high-dose lipophilic statins to be identified as a risk factor of impaired response to clopidogrel and revealed that exposure to further potential drug-drug interactions (DDIs) was too low for analysis. Multidrug adherence monitoring allowed thus dismissing non-adherence as a major contributor to resistance and inter-individual response variability in an outpatient setting. Additionally, it allowed analysing the impact of DDIs according to the actual exposure to the potentially interfering drugs. Further studies based on this methodology are essential to prevent misleading results due to incomplete adherence and gain additional insight into the impact of timing adherence on antiplatelet drug response.

  8. Interventions to increase adherence to acne treatment

    PubMed Central

    Moradi Tuchayi, Sara; Alexander, Tiffany M; Nadkarni, Anish; Feldman, Steven R

    2016-01-01

    Background Adherence to acne medication is poor and is a major reason why treatment plans are ineffective. Recognizing solutions to nonadherence is critical. Objective The purpose of this study is to describe the hurdles associated with acne nonadherence and to provide mechanisms on how to ameliorate them. Methods PubMed database was searched. Of the 419 search results, 29 articles were reviewed to identify hurdles to adherence and corresponding solutions. Results Hurdles to primary nonadherence where the medication is not even started, include lack of knowledge, confusion about usage, weak physician–patient relationship, fear of adverse reactions, and cost. Secondary nonadherence hurdles where the medication is started but is not taken as directed include lack of results, complex regimens, side effects, busy lifestyle, forgetfulness, inconvenience, and psychiatric comorbidity. Solutions to these hurdles include treatment simplification, technology, and dynamic education. Limitations Adherence is affected by numerous factors, but available literature analyzing acne adherence and interventions to improve adherence to treatment is limited. Conclusion There are several hurdles in adhering to acne treatment. Recognition of these hurdles and finding appropriate solutions may be as important to treatment outcomes as choosing the right medication to prescribe. PMID:27784999

  9. Effective extraction of Arabidopsis adherent seed mucilage by ultrasonic treatment

    PubMed Central

    Zhao, Xianhai; Qiao, Lijun; Wu, Ai-Min

    2017-01-01

    The Arabidopsis seed coat is composed of two layers of mucilage, a water-soluble non-adherent outer layer and an adherent inner layer. The non-adherent mucilage can easily be extracted by gentle shaking. However, adherent mucilage is extremely difficult to dissociate from the seed coat. Despite various treatments to extract the adherent mucilage, including EDTA, ammonium oxalate, dilute alkali or acid washes, most of it remains on the seed coat. Here, we show for the first time the extraction of almost all of the adherent mucilage from the Arabidopsis seed coat. Our results demonstrate that ultrasonic treatment was able to extract the adherent mucilage effectively within 20 seconds. Adherent mucilage, like non-adherent mucilage, is mainly composed of rhamnogalacturonan I (RG I). The crystalline cellulose content in adherent mucilage was measured as 3.7 mg g−1 of dry seed. Compared with non-adherent mucilage, the adherent mucilage exhibits relatively stable levels of sugar under various environmental conditions. In all cases, adherent mucilage showed higher levels of sugar than non-adherent mucilage. The cell wall remnant could associate with the adherent mucilage, which could prevent the extraction of the adherent mucilage. Our results show that ultrasonic treatment is an effective method for the quick extraction of Arabidopsis adherent mucilage with little effort. PMID:28091592

  10. Structure factor changes in supercooled yttria-alumina

    SciTech Connect

    Wilding, Martin C.; Greaves, G. Neville; Quang Vu Van; Majerus, Odile; Hennet, Louis

    2009-01-29

    Changes in the structure factor of yttria-alumina liquids have been identified in the supercooled range. Different inter-polyhedral configurations between AlO{sub 4} and YO{sub 6} groups distinguish low density and high density liquid phases. The coexistence of phases at high temperatures have been identified in simultaneous measurements of small angle x-ray scattering.

  11. Formation of {gamma}-alumina nanorods in presence of alanine

    SciTech Connect

    Dabbagh, Hossein A.; Rasti, Elham; Yalfani, Mohammad S.; Medina, Francesc

    2011-02-15

    Graphical abstract: Nanorod aluminas with a possible hexagonal symmetry, high surface area and relatively narrow pore size distribution were obtained. Research highlights: {yields} Research highlights {yields} Boehmite was prepared using a green sol-gel process in the presence of alanine. {yields} Nanorod aluminas with a high surface area were obtained. {yields} Addition of alanine would shape the size of the holes and crevices. {yields} The morphologies of the nanorods were revealed by transmission electron microscope. -- Abstract: Boehmite and alumina nanostructures were prepared using a simple green sol-gel process in the presence of alanine in water medium at room temperature. The uncalcined (dried at 200 {sup o}C) and the calcined materials (at 500, 600 and 700 {sup o}C for 4 h) were characterized using XRD, TEM, SEM, N{sub 2} physisorption and TGA. Nanorod aluminas with a possible hexagonal symmetry, high surface area and relatively narrow pore size distribution were obtained. The surface area was enhanced and crystallization was retarded as the alanine content increased. The morphologies of the nanoparticles and nanorods were revealed by a transmission electron microscope (TEM).

  12. Synthesis and textural evolution of alumina particles with mesoporous structures

    SciTech Connect

    Liu Xun; Peng Tianyou; Yao Jinchun; Lv Hongjin; Huang Cheng

    2010-06-15

    Alumina particles with mesostructures were synthesized through a chemical precipitation method by using different inorganic aluminum salts followed by a heterogeneous azeotropic distillation and calcination process. The obtained mesoporous {gamma}-alumina particles were systematically characterized by the X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption measurement. Effects of the aluminum salt counter anion, pH value and the azeotropic distillation process on the structural or textural evolution of alumina particles were investigated. It is found that Cl{sup -} in the reaction solution can restrain the textural evolution of the resultant precipitates into two-dimensional crystallized pseudoboehmite lamellae during the heterogeneous azeotropic distillation, and then transformed into {gamma}-Al{sub 2}O{sub 3} particles with mesostructures after further calcination at 1173 K, whereas coexisting SO{sub 4}{sup 2-} can promote above morphology evolution and then transformed into {gamma}-Al{sub 2}O{sub 3} nanofibers after calcination at 1173 K. Moreover nearly all materials retain relatively high specific surface areas larger than 100 m{sup 2} g{sup -1} even after calcinations at 1173 K. - Graphical abstract: Co-existing Cl{sup -} is beneficial for the formation of {gamma}-alumina nanoparticles with mesostructures during the precipitation process. Interparticle and intraparticle mesopores can be derived from acidic solution and near neutral solution, respectively.

  13. Nanocomposite formed by titanium ion implantation into alumina

    SciTech Connect

    Spirin, R. E.; Salvadori, M. C. Teixeira, F. S.; Sgubin, L. G.; Cattani, M.; Brown, I. G.

    2014-11-14

    Composites of titanium nanoparticles in alumina were formed by ion implantation of titanium into alumina, and the surface electrical conductivity measured in situ as the implantation proceeded, thus generating curves of sheet conductivity as a function of dose. The implanted titanium self-conglomerates into nanoparticles, and the spatial dimensions of the buried nanocomposite layer can thus be estimated from the implantation depth profile. Rutherford backscattering spectrometry was performed to measure the implantation depth profile, and was in good agreement with the calculated profile. Transmission electron microscopy of the titanium-implanted alumina was used for direct visualization of the nanoparticles formed. The measured conductivity of the buried layer is explained by percolation theory. We determine that the saturation dose, φ{sub 0}, the maximum implantation dose for which the nanocomposite material still remains a composite, is φ{sub 0} = 2.2 × 10{sup 16 }cm{sup −2}, and the corresponding saturation conductivity is σ{sub 0} = 480 S/m. The percolation dose φ{sub c}, below which the nanocomposite still has basically the conductivity of the alumina matrix, was found to be φ{sub c} = 0.84 × 10{sup 16 }cm{sup −2}. The experimental results are discussed and compared with a percolation theory model.

  14. Tritiated alumina serves as reagent for self-labeling analysis

    NASA Technical Reports Server (NTRS)

    Erenrich, E. H.; Klein, P. D.

    1967-01-01

    Tritiated alumina, prepared by exchange of the surface hydroxyl groups with tritiated water, is a suitable reagent for exchange-labeling of specific compounds in low concentrations prior to chromatographic analysis. In a chromatographic column, it detects and measures submicrogram quantities of material.

  15. Template synthesis of gold nanotubes in an anodic alumina membrane.

    PubMed

    Kohli, Punit; Wharton, John E; Braide, Otonye; Martin, Charles R

    2004-07-01

    Nanotube-containing membranes prepared by the template method show promise for use as highly selective filters for membrane-based chemical and biological separations. Most of the work to date has been done on gold nanotubes prepared by electroless deposition of Au within the pores of polymeric filtration membranes. These polymeric filters have very low porosities (< 1%), and, as a result, the flux through Au nanotube membranes based on these templates is very low. In contrast, the other popular template membranes-anodic aluminas-have high porosities-30% to 50%. In spite of this potential advantage of anodic alumina templates, there have been no reports of electrolessly plated Au nanotubes within the pores of these templates. This is because the electroless plating method used to deposit Au nanotubes in polymeric templates does not work in aluminas. We have developed a modified electroless plating strategy that can be used to deposit high-quality Au nanotubes within the pores of the alumina templates. We describe this new plating method here.

  16. On the electrical conductivity of Ti-implanted alumina

    SciTech Connect

    Salvadori, M. C.; Teixeira, F. S.; Cattani, M.; Nikolaev, A.; Savkin, K. P.; Oks, E. M.; Park, H.-K.; Phillips, L.; Yu, K. M.; Brown, I. G.

    2012-03-15

    Ion implantation of metal species into insulators provides a tool for the formation of thin, electrically conducting, surface layers with experimenter-controlled resistivity. High energy implantation of Pt and Ti into alumina accelerator components has been successfully employed to control high voltage surface breakdown in a number of cases. In the work described here we have carried out some basic investigations related to the origin of this phenomenon. By comparison of the results of alumina implanted with Ti at 75 keV with the results of prior investigations of polymers implanted with Pt at 49 eV and Au at 67 eV, we describe a physical model of the effect based on percolation theory and estimate the percolation parameters for the Ti-alumina composite. We estimate that the percolation dose threshold is about 4 x 10{sup 16} cm{sup -2} and the maximum dose for which the system remains an insulator-conductor composite is about 10 x 10{sup 16} cm{sup -2}. The saturation electrical conductivity is estimated to be about 50 S/m. We conclude that the observed electrical conductivity properties of Ti-implanted alumina can be satisfactorily described by percolation theory.

  17. Viscosity of alumina nanoparticles dispersed in car engine coolant

    SciTech Connect

    Kole, Madhusree; Dey, T.K.

    2010-09-15

    The present paper, describes our experimental results on the viscosity of the nanofluid prepared by dispersing alumina nanoparticles (<50 nm) in commercial car coolant. The nanofluid prepared with calculated amount of oleic acid (surfactant) was tested to be stable for more than 80 days. The viscosity of the nanofluids is measured both as a function of alumina volume fraction and temperature between 10 and 50 C. While the pure base fluid display Newtonian behavior over the measured temperature, it transforms to a non-Newtonian fluid with addition of a small amount of alumina nanoparticles. Our results show that viscosity of the nanofluid increases with increasing nanoparticle concentration and decreases with increase in temperature. Most of the frequently used classical models severely under predict the measured viscosity. Volume fraction dependence of the nanofluid viscosity, however, is predicted fairly well on the basis of a recently reported theoretical model for nanofluids that takes into account the effect of Brownian motion of nanoparticles in the nanofluid. The temperature dependence of the viscosity of engine coolant based alumina nanofluids obeys the empirical correlation of the type: log ({mu}{sub nf}) = A exp(BT), proposed earlier by Namburu et al. (author)

  18. Experiments on individual alumina-supported adatoms and clusters

    NASA Astrophysics Data System (ADS)

    Nilius, N.; Cörper, A.; Bozdech, G.; Ernst, N.; Freund, H.-J.

    2001-08-01

    To contribute to an understanding of growth conditions and electronic properties of metal clusters on technologically relevant oxides we have examined the mobility of individual, alumina-supported Pt-adatoms and the optical properties of single supported Ag-clusters. Using field-ion microscopy (FIM) we have prepared and imaged an individual Pt-adatom at approximately 40 K, both on the apex plane of a [1 1 0]-oriented NiAl tip and on a thin alumina film, grown on the same NiAl specimen by oxidation. On the alumina film, the onset temperature for Pt surface diffusion approaches 100 K being distinctively lower than the value 165 K measured on NiAl(1 1 0). Employing the tip of a scanning tunneling microscope (STM) as a local electron source, photon emission from individual, alumina-supported Ag-clusters was spectroscopically analyzed. The occurrence of a distinct emission line is explained by the decay of a collective electron oscillation (Mie-plasmon resonance). For decreasing Ag-cluster diameter, the emission lines (i) shift to higher energies and (ii) their widths increase. To explain these observations, we discuss (i) the reduced screening of the plasmon oscillation due to the Ag 4d electrons and (ii) an enhanced electron surface scattering rate in small clusters.

  19. [Aluminum coordination and active sites on aluminas, Y-zeolites and pillared layered silicates]. Progress report

    SciTech Connect

    Fripiat, J.J.

    1994-02-01

    This report is organized in four sections. In the first the authors will outline structural features which are common to all fine grained alumina, as well as to non-framework alumina in zeolites. This section will be followed by a study of the surface vs. bulk coordination of aluminum. The third section will deal with measurement of the number of acid sites and the scaling of their strength. The fourth and last section will describe three model reactions: the isomerization of 1-butene and of 2 cis-butene; the isomerization and disproportionation of oxtho-xylene; and the transformation of trichloroethane into vinyl chloride followed by the polymerization of the vinyl chloride. The relationship between chemical activity and selectivity and what is known of the local structure of the active catalytic sites will be underlined. Other kinds of zeolites besides Y zeolite have been studied. Instead of the aluminum pillared silicates they found it more interesting to study the substitution of silicon by aluminum in a layered structure containing a permanent porosity (aluminated sepiolite).

  20. Direct visualization of the hydration layer on alumina nanoparticles with the fluid cell STEM in situ

    DOE PAGES

    Firlar, Emre; Çınar, Simge; Kashyap, Sanjay; ...

    2015-05-21

    Rheological behavior of aqueous suspensions containing nanometer-sized powders is of relevance to many branches of industry. Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models. Formation of so-called hydration layer on alumina nanoparticles in water was hypothesized, but never observed experimentally. We report here on the direct visualization of aqueous suspensions of alumina with the fluid cell in situ. We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions.more » We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions. As a result, our findings elucidate the source of high viscosity observed for nanoparticle suspensions and are of direct relevance to many industrial sectors including materials, food, cosmetics, pharmaceutical among others employing colloidal slurries with nanometer-scale particles.« less

  1. Influence of Alumina Additions on the Physical and Chemical Properties of Lithium-iron-phosphate Glasses

    NASA Astrophysics Data System (ADS)

    Liu, Huali; Yang, Ruijuan; Wang, Yinghui; Liu, Shiquan

    Alumina improves the properties and depresses the devitrification of soda-lime-silicate glasses. Herein, the influence of alumina on the glass transition temperature, density, chemical durability, crystallization of lithium-iron-phosphate (LIP) glass has been investigated. As alumina was added to replace the iron oxide in a base LIP glass with the molar composition of Li2O:Fe2O3:P2O5=30:20:50, the alumina-containing glasses have increased Tg, densities and chemical stabilities than the base glass. When the amount of alumina is increased from 2 to 6 mol, the Tg value slightly increases, whereas the density decreases. However, the smallest weight loss is shown for the glass containing 3.2 mol of alumina. The variations of the properties with alumina are explained based on the infrared structure analysis results. In addition, it is found the either the base or the alumina-containing glasses have surface crystallization upon heat-treatments. Under the same treatment conditions, the base glass exhibits a thin layer of crystallization with LiFeP2O7 as the main phase. In contrast, alumina-containing glasses show much higher degree of crystallization, which is further increased with the amount of alumina. This trend is opposite to that of silicate glass. Besides the LiFeP2O7 main phase, Fe7(PO4) phase is also identified in the crystallized alumina-containing glasses.

  2. Processing and Mechanical Properties of Various Zirconia/Alumina Composites for Fuel Cell Applications

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Bansal, Narottam P.

    2002-01-01

    Various electrolyte materials for solid oxide fuel cells were fabricated by hot pressing 10 mol% yttria-stabilized zirconia (10-YSZ) reinforced with two different forms of alumina, particulates and platelets, each containing 0 to 30 mol% alumina. Flexure strength and fracture toughness of both particulate and platelet composites at ambient temperature increased with increasing alumina content, reaching a maximum at 30 mot% alumina. For a given alumina content, strength of particulate composites was greater than that of platelet composites, whereas, the difference in fracture toughness between the two composite systems was negligible. No virtual difference in elastic modulus and density was observed for a given alumina content between particulate and platelet composites. Thermal cycling up to 10 cycles between 200 to 1000 C did not show any effect on strength degradation of the 30 mol% platelet composites, indicative of negligible influence of CTE mismatches between YSZ matrix and alumina grains.

  3. Advanced morphological analysis of patterns of thin anodic porous alumina

    SciTech Connect

    Toccafondi, C.; Stępniowski, W.J.; Leoncini, M.; Salerno, M.

    2014-08-15

    Different conditions of fabrication of thin anodic porous alumina on glass substrates have been explored, obtaining two sets of samples with varying pore density and porosity, respectively. The patterns of pores have been imaged by high resolution scanning electron microscopy and analyzed by innovative methods. The regularity ratio has been extracted from radial profiles of the fast Fourier transforms of the images. Additionally, the Minkowski measures have been calculated. It was first observed that the regularity ratio averaged across all directions is properly corrected by the coefficient previously determined in the literature. Furthermore, the angularly averaged regularity ratio for the thin porous alumina made during short single-step anodizations is lower than that of hexagonal patterns of pores as for thick porous alumina from aluminum electropolishing and two-step anodization. Therefore, the regularity ratio represents a reliable measure of pattern order. At the same time, the lower angular spread of the regularity ratio shows that disordered porous alumina is more isotropic. Within each set, when changing either pore density or porosity, both regularity and isotropy remain rather constant, showing consistent fabrication quality of the experimental patterns. Minor deviations are tentatively discussed with the aid of the Minkowski measures, and the slight decrease in both regularity and isotropy for the final data-points of the porosity set is ascribed to excess pore opening and consequent pore merging. - Highlights: • Thin porous alumina is partly self-ordered and pattern analysis is required. • Regularity ratio is often misused: we fix the averaging and consider its spread. • We also apply the mathematical tool of Minkowski measures, new in this field. • Regularity ratio shows pattern isotropy and Minkowski helps in assessment. • General agreement with perfect artificial patterns confirms the good manufacturing.

  4. The reactive element effect of ceria particle dispersion on alumina growth: A model based on microstructural observations

    PubMed Central

    Wang, X.; Peng, X.; Tan, X.; Wang, F.

    2016-01-01

    The oxidation kinetics of alumina-forming metals can be affected by adding a small amount of a reactive (normally rare earth) element oxide (RExOy) and the segregation of the reactive element (RE) ions to the growing alumina grain boundaries (GBs) has been considered as a responsible reason. However, this interpretation remains a controversial issue as to how RE ions are produced by RExOy which is thermodynamically and chemically stable in metals. The question is answered by a model that is based on transmission electron microscopy (TEM) investigation of a CeO2-dispersed nickel aluminide oxidized in air at 1100 °C. The CeO2 dispersion is incorporated into the alumina scale by the inward growth of inner α-Al2O3, where it partially dissolves producing tetravalent Ce cations which then transform to trivalent cations by trapping electrons. The trivalent cations segregate to the α-Al2O3 GBs and diffuse outward along first the GBs and later the twin boundaries (TBs) in the outer γ-Al2O3 layer, being precipitated as Ce2O3 particles near surface. PMID:27406938

  5. Effect of silicate and aluminate ion adsorption on the reaction of quartz and alumina with caustic solution

    SciTech Connect

    Thornton, S.D.

    1986-05-01

    Caustic consumption is recognized as a problem in enhanced oil recovery by alkaline flooding. Chemical reactions which cause caustic consumption are governed by equilibria between reservoir minerals and alkaline solution. Identification of the individual dissolving and precipitating minerals in a given brine and rock system is a critical step in predicting caustic consumption and scale formation in oil recovery by alkaline flooding. This work demonstrates that ion adsorption may have a significant effect on mineral/alkali equilibria. Powdered quartz and alumina were mixed with alkaline solutions containing 0.01 to 0.1 molar hydroxide ion and added silicate or aluminate ion. Each suspension was sealed in a Teflon bottle and shaken continuously for approximately 1 week at 24/sup 0/ or 70/sup 0/C. Samples of the supernatant were removed periodically and analyzed for the elements silicon and aluminum. The solubilities of quartz and alumina in caustic solutions were found to be reduced significantly by added aluminate and silicate ion, respectively. Adsorption of these ions onto the minerals was also measured. It is postulated that these ions form a protective aluminosilicate layer when they are adsorbed onto the mineral surface. Such an aluminosilicate layer will reduce mineral reactions during alkaline flooding. Two major conclusions result from this work. Adsorbed aluminate and silicate ions can reduce the solubilities of quartz and alumina, respectively. The effect of adsorption on mineral equilibria should be included in a mineral reaction model for alkaline flooding. 18 refs., 5 figs., 8 tabs.

  6. The reactive element effect of ceria particle dispersion on alumina growth: A model based on microstructural observations

    NASA Astrophysics Data System (ADS)

    Wang, X.; Peng, X.; Tan, X.; Wang, F.

    2016-07-01

    The oxidation kinetics of alumina-forming metals can be affected by adding a small amount of a reactive (normally rare earth) element oxide (RExOy) and the segregation of the reactive element (RE) ions to the growing alumina grain boundaries (GBs) has been considered as a responsible reason. However, this interpretation remains a controversial issue as to how RE ions are produced by RExOy which is thermodynamically and chemically stable in metals. The question is answered by a model that is based on transmission electron microscopy (TEM) investigation of a CeO2-dispersed nickel aluminide oxidized in air at 1100 °C. The CeO2 dispersion is incorporated into the alumina scale by the inward growth of inner α-Al2O3, where it partially dissolves producing tetravalent Ce cations which then transform to trivalent cations by trapping electrons. The trivalent cations segregate to the α-Al2O3 GBs and diffuse outward along first the GBs and later the twin boundaries (TBs) in the outer γ-Al2O3 layer, being precipitated as Ce2O3 particles near surface.

  7. Weight loss intervention adherence and factors promoting adherence: a meta-analysis

    PubMed Central

    Lemstra, Mark; Bird, Yelena; Nwankwo, Chijioke; Rogers, Marla; Moraros, John

    2016-01-01

    Background Adhering to weight loss interventions is difficult for many people. The majority of those who are overweight or obese and attempt to lose weight are simply not successful. The objectives of this study were 1) to quantify overall adherence rates for various weight loss interventions and 2) to provide pooled estimates for factors associated with improved adherence to weight loss interventions. Methods We performed a systematic literature review and meta-analysis of all studies published between January 2004 and August 2015 that reviewed weight loss intervention adherence. Results After applying inclusion and exclusion criteria and checking the methodological quality, 27 studies were included in the meta-analysis. The overall adherence rate was 60.5% (95% confidence interval [CI] 53.6–67.2). The following three main variables were found to impact adherence: 1) supervised attendance programs had higher adherence rates than those with no supervision (rate ratio [RR] 1.65; 95% CI 1.54–1.77); 2) interventions that offered social support had higher adherence than those without social support (RR 1.29; 95% CI 1.24–1.34); and 3) dietary intervention alone had higher adherence than exercise programs alone (RR 1.27; 95% CI 1.19–1.35). Conclusion A substantial proportion of people do not adhere to weight loss interventions. Programs supervising attendance, offering social support, and focusing on dietary modification have better adherence than interventions not supervising attendance, not offering social support, and focusing exclusively on exercise. PMID:27574404

  8. Health care providers' support of patients' autonomy, phosphate medication adherence, race and gender in end stage renal disease.

    PubMed

    Umeukeje, Ebele M; Merighi, Joseph R; Browne, Teri; Wild, Marcus; Alsmaan, Hafez; Umanath, Kausik; Lewis, Julia B; Wallston, Kenneth A; Cavanaugh, Kerri L

    2016-12-01

    This study was designed to assess dialysis subjects' perceived autonomy support association with phosphate binder medication adherence, race and gender. A multi-site cross-sectional study was conducted among 377 dialysis subjects. The Health Care Climate (HCC) Questionnaire assessed subjects' perception of their providers' autonomy support for phosphate binder use, and adherence was assessed by the self-reported Morisky Medication Adherence Scale. Serum phosphorus was obtained from the medical record. Regression models were used to examine independent factors of medication adherence, serum phosphorus, and differences by race and gender. Non-white HCC scores were consistently lower compared with white subjects' scores. No differences were observed by gender. Reported phosphate binder adherence was associated with HCC score, and also with phosphorus control. No significant association was found between HCC score and serum phosphorus. Autonomy support, especially in non-white end stage renal disease subjects, may be an appropriate target for culturally informed strategies to optimize mineral bone health.

  9. Aqueous-Phase Preparation of Model HDS Catalysts on Planar Alumina Substrates: Support Effect on Mo Adsorption and Sulfidation.

    PubMed

    Bara, Cédric; Plais, Lucie; Larmier, Kim; Devers, Elodie; Digne, Mathieu; Lamic-Humblot, Anne-Félicie; Pirngruber, Gerhard D; Carrier, Xavier

    2015-12-23

    The role of the oxide support on the structure of the MoS2 active phase (size, morphology, orientation, sulfidation ratio, etc.) remains an open question in hydrotreating catalysis and biomass processing with important industrial implications for the design of improved catalytic formulations. The present work builds on an aqueous-phase surface-science approach using four well-defined α-alumina single crystal surfaces (C (0001), A (112̅0), M (101̅0), and R (11̅02) planes) as surrogates for γ-alumina (the industrial support) in order to discriminate the specific role of individual support facets. The reactivity of the various surface orientations toward molybdenum adsorption is controlled by the speciation of surface hydroxyls that determines the surface charge at the oxide/water interface. The C (0001) plane is inert, and the R (11̅02) plane has a limited Mo adsorption capacity while the A (112̅0) and M (101̅0) surfaces are highly reactive. Sulfidation of model catalysts reveals the highest sulfidation degree for the A (112̅0) and M (101̅0) planes suggesting weak metal/support interactions. Conversely, a low sulfidation rate and shorter MoS2 slabs are found for the R (11̅02) plane implying stronger Mo-O-Al bonds. These limiting cases are reminiscent of type I/type II MoS2 nanostructures. Structural analogies between α- and γ- alumina surfaces allow us to bridge the material gap with real Al2O3-supported catalysts. Hence, it can be proposed that Mo distribution and sulfidation rate are heterogeneous and surface-dependent on industrial γ-Al2O3-supported high-surface-area catalysts. These results demonstrate that a proper control of the γ-alumina morphology is a strategic lever for a molecular-scale design of hydrotreating catalysts.

  10. Predictors and impact of non-adherence in adults with attention-deficit/hyperactivity disorder receiving OROS methylphenidate: results from a randomized, placebo-controlled trial

    PubMed Central

    2013-01-01

    Background Medication non-adherence has an important impact on treatment efficacy and healthcare burden across a range of conditions and therapeutic areas. The aim of this analysis was to determine predictors of non-adherence and impact of non-adherence on treatment response in adults with attention-deficit/hyperactivity disorder (ADHD). Methods Post-hoc analysis of a 13-week randomized, double-blind placebo-controlled study of OROS methylphenidate (MPH) 54 and 72 mg/day. Primary efficacy variable was the Conners’ Adult ADHD Rating Scale – Screening Version (CAARS:O-SV). Daily adherence was calculated as average daily adherence (100 × capsules taken/2), with overall adherence calculated as the average daily adherence. Predictors of adherence were assessed using mixed-effects logistic regression. Descriptive statistics were generated for change in CAARS:O-SV score for adherent (> 95% adherence) and non-adherent subjects. Predictors of change were analyzed using a mixed model. Results Subjects were allocated to OROS MPH (54 mg, n = 87; 72 mg, n = 92) or placebo (n = 97). Mean adherence was 92.6% and 93.3% (OROS MPH 54 and 72 mg/day, respectively), versus 97.5% (placebo). Adherence was higher and less variable in completers. Factors significantly associated with non-adherence included female sex, shorter time since ADHD diagnosis, higher education level (completion of university) and score on the Drug Use Screening Inventory psychiatric disorders subscale. Improvements from baseline in CAARS:O-SV score were numerically greater in subjects defined as adherent than in those who were non-adherent. Significant predictors of CAARS:O-SV change in patients who completed the study included percentage adherence up to the point of assessment (p < 0.0001), baseline score (p < 0.0001) and family history of ADHD (p = 0.0003). Conclusion The results of this analysis suggest that newly diagnosed patients, those with a high score on the DUSI-R psychiatric disorder scale, women

  11. Relationship of Youth Involvement in Diabetes-Related Decisions to Treatment Adherence

    PubMed Central

    Miller, Victoria A.; Jawad, Abbas F.

    2014-01-01

    The aim of this study was to examine the relationship of youth’s involvement in diabetes-related decisions to adherence. Children and adolescents (8–19 years) and their parents (N = 89) completed the Decision Making Involvement Scale (DMIS) and the Self Care Inventory, a self-report measure of adherence. After controlling for youth age, the degree to which youth expressed an opinion and information to parents was associated with better parent- and youth- reported adherence. The degree to which parents expressed an opinion and information to youth was associated with worse parent-reported adherence. Joint decision-making behaviors (e.g., negotiation; provision of options) also were associated with better youth-reported adherence. Encouraging youth to express opinions and share illness-related information with parents during illness management discussions may improve adherence. Additional research is needed to identify mechanisms of effect and determine associations between decision making involvement and health behaviors and outcomes over time. PMID:24659299

  12. Adherence to a Mediterranean diet and Alzheimer's disease risk in an Australian population

    PubMed Central

    Gardener, S; Gu, Y; Rainey-Smith, S R; Keogh, J B; Clifton, P M; Mathieson, S L; Taddei, K; Mondal, A; Ward, V K; Scarmeas, N; Barnes, M; Ellis, K A; Head, R; Masters, C L; Ames, D; Macaulay, S L; Rowe, C C; Szoeke, C; Martins, R N

    2012-01-01

    The Mediterranean diet (MeDi), due to its correlation with a low morbidity and mortality for many chronic diseases, has been widely recognised as a healthy eating model. We aimed to investigate, in a cross-sectional study, the association between adherence to a MeDi and risk for Alzheimer's disease (AD) and mild cognitive impairment (MCI) in a large, elderly, Australian cohort. Subjects in the Australian Imaging, Biomarkers and Lifestyle Study of Ageing cohort (723 healthy controls (HC), 98 MCI and 149 AD participants) completed the Cancer Council of Victoria Food Frequency Questionnaire. Adherence to the MeDi (0- to 9-point scale with higher scores indicating higher adherence) was the main predictor of AD and MCI status in multinominal logistic regression models that were adjusted for cohort age, sex, country of birth, education, apolipoprotein E genotype, total caloric intake, current smoking status, body mass index, history of diabetes, hypertension, angina, heart attack and stroke. There was a significant difference in adherence to the MeDi between HC and AD subjects (P<0.001), and in adherence between HC and MCI subjects (P<0.05). MeDi is associated with change in Mini-Mental State Examination score over an 18-month time period (P<0.05) in HCs. We conclude that in this Australian cohort, AD and MCI participants had a lower adherence to the MeDi than HC participants. PMID:23032941

  13. Factors Influencing Antiretroviral Adherence and Virological Outcomes in People Living with HIV in the Highlands of Papua New Guinea.

    PubMed

    Gare, Janet; Kelly-Hanku, Angela; Ryan, Claire E; David, Matthew; Kaima, Petronia; Imara, Ulato; Lote, Namarola; Crowe, Suzanne M; Hearps, Anna C

    2015-01-01

    Adherence to antiretroviral therapy (ART) is paramount for virological suppression and positive treatment outcomes. ART has been rapidly scaled up in Papua New Guinea (PNG) in recent years, however clinical monitoring of HIV+ individuals on ART is limited. A cross-sectional study was conducted at two major sexual health clinics in high HIV prevalence provinces in the Highlands Region of PNG to assess ART adherence, factors affecting adherence and the relationship between ART adherence and virological outcomes. Ninety-five HIV+ individuals were recruited and administered a questionnaire to gather demographic and ART adherence information whilst clinical data and pill counts were extracted from patient charts and blood was collected for viral load testing. Bivariate analysis was performed to identify independent predictors of ART adherence. Fourteen percent (n = 12) of participants showed evidence of virological failure. Although the majority of participants self-reported excellent ART adherence in the last seven days (78.9%, 75/91), pill count measurements indicated only 40% (34/84) with >95% adherence in the last month. Taking other medications while on ART (p = 0.01) and taking ART for ≥1 year (p = 0.037) were positively associated with adherence by self-report and pill count, respectively. Participants who had never heard of drug resistance were more likely to show virological failure (p = 0.033). Misconception on routes of HIV transmission still persists in the studied population. These findings indicate that non-adherence to ART is high in this region of PNG and continued education and strategies to improve adherence are required to ensure the efficacy of ART and prevent HIV drug resistance.

  14. Psychological perspective of medication adherence in transplantation

    PubMed Central

    De Pasquale, Concetta; Veroux, Massimiliano; Fornaro, Michele; Sinagra, Nunzia; Basile, Giusi; Gozzo, Cecilia; Santini, Roberta; Costa, Alessandra; Pistorio, Maria Luisa

    2016-01-01

    AIM To identify the risk factors and the post-transplant psychological symptoms that affect adherence to therapy in a population of kidney transplant recipients. METHODS The study examined the psychological variables likely responsible for the non-adherent behavior using a psychological-psychiatric assessment, evaluation of the perception of patients’ health status, and an interview regarding the anti-rejection drug therapy assumption. The study included 74 kidney transplant recipients. RESULTS Individuals with a higher level of education and more years since transplantation showed better mental balance. Regarding gender, women appeared to be less adherent to therapy. Further, the years since transplantation adversely affected the proper pharmacological assumption. Adherence to therapy did not significantly change with the mental health index. CONCLUSION The biopsychosocial illness model provides a conceptual frame of reference in which biological, psychological, and social aspects take on the same importance in the adherence to treatment protocols. For effective management, it is necessary to understand the patients’ personal experiences, their assumptions about the disease, health status perception, and mood, and to identify any “barriers” that could cause them to become noncompliant. PMID:28058225

  15. Adherence to Glycemic Monitoring in Diabetes

    PubMed Central

    Patton, Susana R.

    2015-01-01

    Glucose monitoring either by self-monitoring of blood glucose (SMBG) or continuous glucose monitoring (CGM) plays an important role in diabetes management and in reducing risk for diabetes-related complications. However, despite evidence supporting the role of glucose monitoring in better patient health outcomes, studies also reveal relatively poor adherence rates to SMBG and CGM use and numerous patient-reported barriers. Fortunately, some promising intervention strategies have been identified that promote at least short-term improvements in patients’ adherence to SMBG. These include education, problem solving, contingency management, goal setting, cognitive behavioral therapy, and motivational interviewing. Specific to CGM, interventions to promote greater use among patients are currently under way, yet one pilot study provides data suggesting better maintenance of CGM use in patients showing greater readiness for behavior change. The purpose of this review is to summarize the literature specific to glucose monitoring in patients with diabetes focusing specifically on current adherence rates, barriers to monitoring, and promising intervention strategies that may be ready to deploy now in the clinic setting to promote greater patient adherence to glucose monitoring. Yet, to continue to help patients with diabetes adhere to glucose monitoring, future research is needed to identify the treatment strategies and the intervention schedules that most likely lead to long-term maintenance of optimal glycemic monitoring levels. PMID:25591853

  16. The association between adherence to the New Nordic Diet and diet quality

    PubMed Central

    Bjørnarå, Helga Birgit; Øverby, Nina Cecilie; Stea, Tonje Holte; Torstveit, Monica Klungland; Hillesund, Elisabet Rudjord; Andersen, Lene Frost; Berntsen, Sveinung; Bere, Elling

    2016-01-01

    Background Previous studies have reported a positive association between scoring on healthy Nordic diet scales and the intake of healthy foods and nutrients, and also with higher intake of meat, sweets, cakes, and energy in general. These studies have used the same food frequency questionnaire (FFQ) responses for constructing the diet score as for calculating intakes of foods and nutrients. Thus, it is not clear whether the coexistence of healthy and less healthy dietary aspects among adherers to Nordic diets would occur even though separate methods were applied for exploring these relations. Objective To assess the association between adherence to the New Nordic Diet (NND), derived from an FFQ, and diet quality, determined from two 24-h dietary recall interviews. Design In total, 65 parents of toddlers in Southern Norway answered the NND FFQ and two 24-h dietary recall interviews. NND adherence was determined from the FFQ and categorized into low, medium, and high adherence. The two 24-h recalls provided data for the intake of specific foods and nutrients, selected on the basis of the Norwegian food-based guidelines as an indicator of a healthy diet. The Kruskal–Wallis test was used for assessing differences in food and nutrient intake across NND groups. Results High NND adherence derived from FFQ was associated with a high intake of fruits (p=0.004) and fiber (p=0.02), and a low intake of meat (p=0.004) and margarines (p=0.05), derived from recalls. A larger proportion of high NND adherers (68%) complied with the national dietary recommendation targeting meat intake compared with low NND adherers (29%) (p=0.04). Conclusion The present study showed that higher NND adherence measured with FFQ was associated with a higher intake of selected healthy foods and nutrients, measured with recalls. However, a higher intake of meat, sweets, and energy, as earlier reported, was not observed. PMID:27257844

  17. Unoxidized Graphene/Alumina Nanocomposite: Fracture- and Wear-Resistance Effects of Graphene on Alumina Matrix

    PubMed Central

    Kim, Hyo Jin; Lee, Sung-Min; Oh, Yoon-Suk; Yang, Young-Hwan; Lim, Young Soo; Yoon, Dae Ho; Lee, Changgu; Kim, Jong-Young; Ruoff, Rodney S.

    2014-01-01

    It is of critical importance to improve toughness, strength, and wear-resistance together for the development of advanced structural materials. Herein, we report on the synthesis of unoxidized graphene/alumina composite materials having enhanced toughness, strength, and wear-resistance by a low-cost and environmentally benign pressure-less-sintering process. The wear resistance of the composites was increased by one order of magnitude even under high normal load condition (25 N) as a result of a tribological effect of graphene along with enhanced fracture toughness (KIC) and flexural strength (σf) of the composites by ~75% (5.60 MPa·m1/2) and ~25% (430 MPa), respectively, compared with those of pure Al2O3. Furthermore, we found that only a small fraction of ultra-thin graphene (0.25–0.5 vol%, platelet thickness of 2–5 nm) was enough to reinforce the composite. In contrast to unoxidized graphene, graphene oxide (G-O) and reduced graphene oxide (rG-O) showed little or less enhancement of fracture toughness due to the degraded mechanical strength of rG-O and the structural defects of the G-O composites. PMID:24898792

  18. Investigating factors associated with adherence behaviour in patients with chronic myeloid leukemia: an observational patient-centered outcome study

    PubMed Central

    Efficace, F; Baccarani, M; Rosti, G; Cottone, F; Castagnetti, F; Breccia, M; Alimena, G; Iurlo, A; Rossi, A R; Pardini, S; Gherlinzoni, F; Salvucci, M; Tiribelli, M; Vignetti, M; Mandelli, F

    2012-01-01

    Background: Optimal adherence to imatinib therapy is of paramount importance to maximise treatment effectiveness in patients with chronic myeloid leukaemia (CML). The main objective of this study was to investigate patient-reported personal factors associated with adherence behaviour. Methods: Analysis was conducted on 413 CML patients receiving long-term therapy with imatinib. Adherence behaviour was measured with the Morisky Medication Adherence Scale and personal factors investigated included: quality of life, perceived social support, fatigue, symptom burden, psychological wellbeing and desire for additional information. Key socio-demographic and treatment-related factors were also taken into account. Univariate and multivariate logistic regression analyses were used to investigate factors associated with optimal adherence to therapy. Results: In all, 53% of patients reported an optimal adherence behaviour. The final multivariate model retained the following variables as independent predictors of optimal adherence to therapy: desire for more information (ref. no), odds ratio (OR)=0.43 (95% confidence interval (CI), 0.29–0.66; P<0.001), social support (higher score representing greater support), OR=1.29 (95% CI, 1.11–1.49; P<0.001) and concomitant drug burden (ref. no), OR=1.82 (95% CI, 1.18–2.80; P=0.006). Conclusion: This study suggests that a higher level of social support, satisfaction with information received and concomitant drug burden are the main factors associated with greater adherence to long-term imatinib therapy. PMID:22871884

  19. Adolescents in southern regions of Italy adhere to the Mediterranean diet more than those in the northern regions.

    PubMed

    Noale, Marianna; Nardi, Mariateresa; Limongi, Federica; Siviero, Paola; Caregaro, Lorenza; Crepaldi, Gaetano; Maggi, Stefania

    2014-09-01

    There is a large amount of literature regarding the benefits of the Mediterranean diet in the adult population; however, there is growing curiosity about the individuals who naturally adhere to those principles early in life. The "Evaluation of Dietary Habits in Adolescents," carried out by the National Research Council of Italy in 2009, is a survey that aimed to assess the dietary habits and lifestyles of Italian adolescents and their adherence to the Mediterranean diet. We hypothesized that there would be differences across regions, with a higher adherence in Southern Italy compared with Northern Italy based on geography. The survey was conducted in 3 different geographic locations in Italy and included a convenience sample of adolescents who attended either a middle or high school. The participants were asked to fill out a questionnaire concerning demographic data, lifestyle factors, and eating patterns, and scores were assigned according to adherence to the Mediterranean diet, as calculated using Trichopoulou's Mediterranean diet scale. The final sample included 565 adolescents, between 12 and 19 years old, who attended school in the northeastern, northwestern, or southern regions of Italy in 2009. According to the findings, 38.6% of the respondents had scores indicating a low adherence to the Mediterranean diet, whereas only 14% had scores showing a high adherence. Teenagers from the Southern region showed the highest adherence. Those with a high adherence to the Mediterranean diet consumed higher quantities of fiber, iron, vitamin B6, vitamin C, folic acid, vitamin A, vitamin D, and monounsaturated fats.

  20. Self-Assessment of Adherence to Medication: A Case Study in Campania Region Community-Dwelling Population

    PubMed Central

    Menditto, Enrica; Guerriero, Francesca; Orlando, Valentina; Crola, Catherine; Di Somma, Carolina; Illario, Maddalena; Morisky, Donald E.; Colao, Annamaria

    2015-01-01

    Objectives. The aim of the study was to assess self-reported medication adherence measure in patients selected during a health education and health promotion focused event held in the Campania region. The study also assessed sociodemographic determinants of adherence. Methods. An interviewer assisted survey was conducted to assess adherence using the Italian version of the 8-item Morisky Medication Adherence Scale (MMAS-8). Participants older than 18 years were interviewed by pharmacists while waiting for free-medical checkup. Results. A total of 312 participants were interviewed during the Health Campus event. A total of 187 (59.9%) had low adherence to medications. Pearson's bivariate correlation showed positive association between the MMAS-8 score and gender, educational level and smoking (P < 0.05). A multivariable analysis showed that the level of education and smoking were independent predictors of adherence. Individuals with an average level of education (odds ratio (OR), 2.21, 95% confidence interval (CI), 1.08–4.52) and nonsmoker (odds ratio (OR) 1.87, 95% confidence interval (CI), 1.04–3.35) were found to be more adherent to medication than those with a lower level of education and smoking. Conclusion. The analysis showed very low prescription adherence levels in the interviewed population. The level of education was a relevant predictor associated with that result. PMID:26346487

  1. Blood Pressure Treatment Adherence and Control after Participation in the ReHOT

    PubMed Central

    de Jesus, Nathália Silva; Nogueira, Armando da Rocha; Pachu, Cacilda Oliveira; Luiz, Ronir Raggio; de Oliveira, Glaucia Maria Moraes

    2016-01-01

    Background Lack of adherence to pharmacological treatment is one of the main causes of low control rates in hypertension. Objective To verify treatment adherence and associated factors, as well as blood pressure (BP) control in participants of the Resistant Hypertension Optimal Treatment (ReHOT) clinical trial. Method Cross-sectional study including all 109 patients who had completed the ReHOT for at least 6 months. We excluded those participants who failed to respond to the new recruitment after three phone contact attempts. We evaluated the BP control by ambulatory BP monitoring (ABPM; controlled levels: 24-hour systolic and diastolic BP < 130 x 80 mmHg) and analyzed the patients' treatment adherence using the Morisky Medication Adherence Scale (MMAS) questionnaire validated by Bloch, Melo, and Nogueira (2008). The statistical analysis was performed with the software IBM SPSS statistics 21.0. We tested the normality of the data distribution with kurtosis and skewness. The variables tested in the study are presented with descriptive statistics. Comparisons between treatment adherence and other variables were performed with Student's t test for independent variables and Pearson's chi-square or Fisher's exact test. To conduct analyses among patients considering adherence to treatment and BP control, we created four groups: G0, G1, G2, and G3. We considered a 5% significance level in all tests. Results During the ReHOT, 80% of the patients had good BP control and treatment adherence. Of 96 patients reevaluated in the present study, only 52.1% had controlled hypertension when assessed by ABPM, while 31.3% were considered adherent by the MMAS. Regarding other ABPM measures, we observed an absence of a nocturnal dip in 64.6% of the patients and a white-coat effect and false BP control in 23% and 12.5%, respectively. Patients' education level showed a trend towards being a determinant factor associated with lack of adherence (p = 0.05). Resistant hypertension and number

  2. Bipolar disorder: medication adherence and life contentment.

    PubMed

    Darling, Carol Anderson; Olmstead, Spencer B; Lund, Victoria E; Fairclough, Jaime F

    2008-06-01

    Using family stress theory, we examined the influence of family and health stress, level of coping, and internal health locus of control upon the life contentment of individuals diagnosed with bipolar disorder (BPD) who were either adherent or nonadherent to their medication regimens. A survey-interview design was used with a sample of 100 individuals diagnosed with BPD; 50 participants were adherent to their medication and 50 were considered nonadherent. The results indicated that the adherent group had fewer health problems and more resources for coping with stress, possessed a stronger belief that their own behaviors controlled their health status, and had higher life contentment compared to nonadherent participants. For the participants in this study, internal health locus of control had the greatest total effect on life contentment followed by family coping. Implications included the need to comprehensively assess each individual regarding the multiple factors in one's life that influence an effective treatment regimen.

  3. Factors influencing adherence in CML and ways to improvement: Results of a patient-driven survey of 2546 patients in 63 countries.

    PubMed

    Geissler, Jan; Sharf, Giora; Bombaci, Felice; Daban, Mina; De Jong, Jan; Gavin, Tony; Pelouchova, Jana; Dziwinski, Euzebiusz; Hasford, Joerg; Hoffmann, Verena Sophia

    2017-03-13

    Optimal adherence to CML therapy is of key importance to maximize treatment effectiveness. Two clinical studies (ADAGIO and Hammersmith) have proven a clear correlation between adherence and achieving optimal treatment response and have revealed that non-adherence is common in CML patients (Marin et al. in J Clin Oncol 28(24):2381-2388, 2010, Noens et al. in Haematologica 99(33):437-447, 2014). The aim of this study is to assess the extent of suboptimal adherence and to investigate motivations and behavioural patterns of adherence in a worldwide patient sample. Questionnaires were provided by the CML Advocates Network and were filled in by patients online and offline. Patient characteristics, treatment and motivations were collected. Adherence was assessed by the 8-item Morisky Medication Adherence scale. Logistic regression models were fitted to investigate the influence of different factors on adherence. Overall, 2 546 questionnaires from 63 countries and 79 CML patient organisations were evaluable. 32.7% of participants were highly adherent, 46.5% were in the medium and 20.7% in the low adherence group. Factors increasing the probability of being in the high adherence group are older age, male sex, management of side effects, only one tablet per day and feeling well informed about CML by the doctor. More than 2 years since diagnosis were significantly lowering the chance as was the use of reminding tools. Living arrangements, multiple medication and personal payment obligations increased the probability to be at least in the medium adherent group. This is the most comprehensive study conducted to date to gain knowledge about factors causing non-adherence in CML. Better information on the disease, medication and management of side effects, supported by haematologists, is key to improve adherence.

  4. Cell Phone Intervention to Improve Adherence

    PubMed Central

    Marciel, Kristen K.; Saiman, Lisa; Quittell, Lynne M.; Dawkins, Kevin; Quittner, Alexandra L.

    2010-01-01

    Summary Background Treatment regimens for patients with cystic fibrosis (CF) are time-consuming and complex, resulting in consistently low adherence rates. To date, few studies have evaluated innovative technologies to improve adherence in this population. Current infection control guidelines for patients with CF seek to minimize patient-to-patient transmission of potential pathogens. Thus, interventions must avoid face-to-face contact and be delivered individually, limiting opportunities for peer support. This study aimed to develop and assess a web-enabled cell phone, CFFONE™, designed to provide CF information and social support to improve adherence in adolescents with CF. Methods The acceptability, feasibility, and utility of CFFONE™ were evaluated with health care professionals (n = 17) adolescents with CF aged 11–18 years old (n = 12), adults with CF aged 21–36 years old (n = 6), parents of adolescents with CF (n = 12), and technology experts (n = 8). Adolescents also tested a prototype of CFFONE™ (n = 9). Qualitative and quantitative data were collected. Results Focus group data with health care = professionals indicated a need for this intervention, and indicated that CFFONE™ would be likely to improve knowledge and social support, and somewhat likely to improve adherence. Adolescent, adults, and parents all rated CFFONE™ as likely to improve adherence. Technology experts rated the prototype design and format as appropriate. Conclusions The current study provided some support from key stakeholders for this intervention to improve adherence in adolescents with CF. Next steps include a multi-center trial of the efficacy and safety of CFFONE™. PMID:20054860

  5. A Review of Treatment Adherence Measurement Methods

    PubMed Central

    Schoenwald, Sonja K.; Garland, Ann F.

    2013-01-01

    Fidelity measurement is critical for testing the effectiveness and implementation in practice of psychosocial interventions. Adherence is a critical component of fidelity. The purposes of this review were to catalogue adherence measurement methods and assess existing evidence for the valid and reliable use of scores they generate and feasibility of use in routine care settings. Method A systematic literature search identified articles published between 1980–2008 reporting studies of evidence-based psychosocial treatments for child or adult mental health problems, and including mention of adherence or fidelity assessment. Coders abstracted data on the measurement methods and clinical contexts of their use. Results 341 articles were reviewed in which 249 unique adherence measurement methods were identified. These methods assessed many treatment models, although more than half (59%) assessed Cognitive Behavioral Treatments. The measurement methods were used in studies with diverse clientele and clinicians. The majority (71.5%) of methods were observational. Information about psychometric properties was reported for 35% of the measurement methods, but adherence-outcomes relationships were reported for only ten percent. Approximately one third of the measures were used in community- based settings. Conclusions Many adherence measurement methods have been used in treatment research; however, little reliability and validity evidence exists for the use of these methods. That some methods were used in routine care settings suggests the feasibility of their use in practice; however, information about the operational details of measurement, scoring, and reporting is sorely needed to inform and evaluate strategies to embed fidelity measurement in implementation support and monitoring systems. PMID:22888981

  6. The Effect of Group Psychoeducation Program on Medication Adherence in Patients with Bipolar Mood Disorders: a Randomized Controlled Trial

    PubMed Central

    Rahmani, Farnaz; Ebrahimi, Hossein; Ranjbar, Fatemeh; Razavi, Seyed Sajjad; Asghari, Elnaz

    2016-01-01

    Introduction: Medication nonadherence is highly prevalent in patients with bipolar disorders and often results in worsening disease prognosis. The purpose of this study was to investigate the effect of group psychoeducation on medication adherence in female patients with bipolar mood disorder type I. Methods: This randomized controlled trial was conducted on 76 patients with bipolar mood disorder admitted in female psychiatric wards of Razi teaching hospital, Tabriz, Iran. The participants were selected by convenience sampling method and were randomly assigned to experimental and control groups. Patients in experimental group received 10 continuous 90 minutes sessions of psychoeducation, two times a week. Medication adherence was measured using the medicine check list and medication adherence rating scale (MARS) before and after intervention. Data analysis was performed with SPSS ver.13. Results: There was no significant difference between two groups regarding medication adherence before the intervention. After the study intervention, the mean scores of medication adherence check list and medication adherence rating scale in the experimental group were significantly higher than the control group. Conclusion: Since group psychoeducation was effective in improving patients' medication adherence, it could be recommended for psychiatric nurses to apply this intervention in the clinical setting. PMID:28032073

  7. Adherence to Cardiovascular Medications: Lessons Learned and Future Directions

    PubMed Central

    Kronish, Ian M; Ye, Siqin

    2013-01-01

    Approximately 50% of patients with cardiovascular disease and/or its major risk factors have poor adherence to their prescribed medications. Finding novel methods to help patients improve their adherence to existing evidence-based cardiovascular drug therapies has enormous potential to improve health outcomes while potentially reducing health care costs. The goal of this report is to provide a review of the current understanding of adherence to cardiovascular medications from the point of view of prescribing clinicians and cardiovascular researchers. Key topics addressed include: 1) definitions of medication adherence; 2) prevalence and impact of non-adherence; 3) methods for assessing medication adherence; 4) reasons for poor adherence; and 5) approaches to improving adherence to cardiovascular medications. For each of these topics, the report seeks to identify important gaps in knowledge and opportunities for advancing the field of cardiovascular adherence research. PMID:23621969

  8. Adherence discourse among African-American women taking HAART

    PubMed Central

    Sankar, A.; Luborsky, M.; Schuman, P.; Roberts, G.

    2014-01-01

    Low adherence is the single most important challenge to controlling HIV through the use of high acting anti-retrovirals (HAART). Non-adherence poses an immediate threat to individuals who develop resistant forms of the virus as well as a public health threat if those individuals pass on treatment-resistant forms of the virus. To understand the concerns and perceptions that promote or deter adherence to antiretroviral medication by HIV-positive African-American women, we conducted in-depth interviews with 15 African-American women taking HAART. We focused on the discourse and narratives women use in talking about their adherence practice. Discourse analysis was utilized to identify and explore the sources of influence used by these women in describing their adherence practice. Roughly a third of the sample fell into each of the three self-assessed adherence categories: always adherent, mostly adherent and somewhat adherent. Among the ‘always adherent’, 80% of the sources of influence cited supported adherence, while only 48% and 47% of the authoritative sources cited by women in the ‘mostly’ and ‘somewhat’ categories supported adherence. Each self-assessed adherence group was characterized by its own distinctive discourse style. Findings suggest that adherence to HAART among African-American HIV-positive women would be improved by identifying those influences undermining adherence. Focused study of the ‘always adherent’ types is recommended. PMID:11940279

  9. Alumina lightweight ceramics modified with plasma synthesized nanopowders

    NASA Astrophysics Data System (ADS)

    Zake, I.; Svinka, R.; Svinka, V.; Palcevskis, E.

    2011-12-01

    The aim of this study is to clarify possibilities of using plasma synthesized Al2O3 and SiC nanopowders as additives in alumina lightweight ceramics prepared by slip casting. Each plasma synthesized nanopowder (PSNP) was incorporated in the material by a different method, because of their diverse influence on the properties of slip. Al2O3 PSNP was introduced in the matrix in form of aqueous suspension. SiC nanopowder was added directly to raw materials. Bending strength, bulk density, apparent porosity and thermal shock resistance were determined to evaluate the influence of these additives. The effect of Al2O3 PSNP addition on the properties of material depends on the initial sintering temperature. SiC particles during sintering oxidize into SiO2 and then in the reaction with alumina form mullite. Addition of SiC considerably improves bending strength and thermal shock resistance.

  10. Measurements of prompt radiation induced conductivity of alumina and sapphire

    SciTech Connect

    Hartman, E. Frederick; Zarick, Thomas Andrew; Sheridan, Timothy J.; Preston, Eric F.

    2011-04-01

    We performed measurements of the prompt radiation induced conductivity in thin samples of Alumina and Sapphire at the Little Mountain Medusa LINAC facility in Ogden, UT. Five mil thick samples were irradiated with pulses of 20 MeV electrons, yielding dose rates of 1E7 to 1E9 rad/s. We applied variable potentials up to 1 kV across the samples and measured the prompt conduction current. Analysis rendered prompt conductivity coefficients between 1E10 and 1E9 mho/m/(rad/s), depending on the dose rate and the pulse width for Alumina and 1E7 to 6E7 mho/m/(rad/s) for Sapphire.

  11. Adsorption of copper on a γ-alumina support

    NASA Astrophysics Data System (ADS)

    Papas, Brian N.; Whitten, Jerry L.

    2016-09-01

    The interaction of a Cu atom with two model γ-alumina surfaces was examined using configuration interaction theory. These two surfaces are centered on Td and Oh coordinated Al atoms near the surface, with both surfaces fully hydroxylated. Copper was found to bind to non-hydrogenated oxygen atoms in the surface by 25 kcal/mol, with the possibility that an under coordinated aluminum site may bind copper much more strongly. Vacancies formed by the removal of hydrogen atoms, or by removal of OH groups, were found to bind Cu by values ranging from 40 to 98 kcal/mol. The interaction of a planar Cu7 particle with an exposed Td coordinated Al atom at an OH vacancy site was found to lead to decomposition of the particle and partial absorption of the Cu into the alumina surface.

  12. Deterministic processing of alumina with ultra-short laser pulses

    SciTech Connect

    Furmanski, J; Rubenchik, A M; Shirk, M D; Stuart, B C

    2007-06-27

    Ultrashort pulsed lasers can accurately ablate materials which are refractory, transparent, or are otherwise difficult to machine by other methods. The typical method of machining surfaces with ultrashort laser pulses is by raster scanning, or the machining of sequentially overlapping linear trenches. Experiments in which linear trenches were machined in alumina at various pulse overlaps and incident fluences are presented, and the dependence of groove depth on these parameters established. A model for the machining of trenches based on experimental data in alumina is presented, which predicts and matches observed trench geometry. This model is then used to predict optimal process parameters for the machining of trenches for maximal material removal rate for a given laser.

  13. Real-time polarimetric biosensing using macroporous alumina membranes

    NASA Astrophysics Data System (ADS)

    Álvarez, Jesús; Sola, Laura; Platt, Geoff; Cretich, Marina; Swann, Marcus; Chiari, Marcella; Hill, Daniel; Martínez-Pastor, Juan

    2013-05-01

    We report the first demonstration of real-time biosensing in free standing macroporous alumina membranes. The membranes with their 200 nm diameter pores are ideal candidates for biosensing applications where fast response times for small sample volumes are needed as they allow analytes to flow through the pores close to the bioreceptors immobilized on the pores walls. A bulk refractive index sensitivity of 5.2x10-6 refractive index units was obtained from signal responses to different concentrations of NaCl solutions flowing through the pores. Finally, after functionalizing the alumina pore surfaces with an epoxysilane and then spotting it with β-Lactoglobulin protein, the interactions between the β-lactoglobulin and rabbit anti-β-lactoglobulin, as well as the interaction between the rabbit anti-β-lactoglobulin and a secondary antibody anti-rabbit Immunoglobulin G were monitored in real-time.

  14. Melt processing of Bi--2212 superconductors using alumina

    DOEpatents

    Holesinger, Terry G.

    1999-01-01

    Superconducting articles and a method of forming them, where the superconducting phase of an article is Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.y (Bi-2212). Alumina is combined with Bi-2212 powder or Bi-2212 precursor powder and, in order to form an intimate mixture, the mixture is melted and rapidly cooled to form a glassy solid. The glassy solid is comminuted and the resulting powder is combined with a carrier. An alternative to melting is to form the mixture of nanophase alumina and material having a particle size of less than about 10 microns. The powder, with the carrier, is melt processed to form a superconducting article.

  15. Diffusion bonding of titanium-titanium aluminide-alumina sandwich

    SciTech Connect

    Wickman, H.A.; Chin, E.S.C.; Biederman, R.R.

    1995-12-31

    Diffusion bonding of a metallic-intermetallic-ceramic sandwich is of interest for potential armor applications. Low cost titanium, titanium diboride reinforced titanium aluminide (Ti-48at.%Al), and aluminum oxide are diffusion bonded in a vacuum furnace between 1,000 C and 1,400 C. Metallographic examination of the prior bonding interface showed excellent metallurgical coupling between the Ti-48at.%Al composite and the low cost Ti. A series of microstructures representative of phases consistent with a hypothetical Ti-Al-B phase diagram is visible. The alumina-Ti-48at.%Al interfacial bond is achieved through penetration of titanium-aluminum phases into the existing alumina porosity. A detailed microstructural analysis identifying mechanisms of interfacial bonding will be presented for each interfacial zone.

  16. A sodium/beta-alumina/nickel chloride secondary cell

    NASA Astrophysics Data System (ADS)

    Galloway, R. C.

    1987-01-01

    Nickel chloride has been studied in a cell system, sodium/beta alumina/sodium tetrachloroaluminate/nickel chloride, which is analogous to two existing rechargeable high energy density cells based on iron chloride and sodium sulfur. The cell reaction can be written as: 2Na + NiCl2 yields on discharge Ni + 2NaCl. The positive electrode, conveniently assembled in the discharged state, was a nickel/sodium choride sinter. Molten sodium tetrachloroaluminate electrolyte (NaAlCl4) acted as intermediate between electrode and beta alumina tube. Encouraging results were obtained in terms of low resistances and rates of discharge for cells up to 20-Ah capacity. Cells were operated over the temperature range from 230 to 400 C where the OCV of the cell reaction varied from 2.60 V to 2.56 V.

  17. Strain-Induced Deformation in Magnesia-Alumina Layered Composites

    SciTech Connect

    Kim, Chang Soo; Lombardo, Stephen J; Winholtz, Robert A

    2008-06-18

    Ceramic beams are induced in situ to form complex shapes at elevated temperature without the application of an external stress. This process has been demonstrated for thin alumina substrates coated with a layer of magnesia. The internal strain causing the substrates to deform at elevated temperature arises as a consequence of strain mismatch accompanying the penetration of the coating into the substrate. The magnitude of the deformation depends on the amount of coating applied, on the thickness of the substrate, on the density of the substrate, and on the temperature. During exposure of the beams to elevated temperature, the magnesia coating reacts with the alumina substrate to form the spinel phase; the resulting volume change accompanying the phase transformation is likely the predominant driving force for deformation.

  18. Process for High-Rate Fabrication of Alumina Nanotemplates

    NASA Technical Reports Server (NTRS)

    Myung, Nosang; Fleurial, Jean-Pierre; Yun, Minhee; West, William; Choi, Daniel

    2007-01-01

    An anodizing process, at an early stage of development at the time of reporting the information for this article, has shown promise as a means of fabricating alumina nanotemplates integrated with silicon wafers. Alumina nanotemplates are basically layers of alumina, typically several microns thick, in which are formed approximately regular hexagonal arrays of holes having typical diameters of the order of 10 to 100 nm. Interest in alumina nanotemplates has grown in recent years because they have been found to be useful as templates in the fabrication of nanoscale magnetic, electronic, optoelectronic, and other devices. The present anodizing process is attractive for the fabrication of alumina nanotemplates integrated with silicon wafers in two respects: (1) the process involves self-ordering of the holes; that is, the holes as formed by the process are spontaneously arranged in approximately regular hexagonal arrays; and (2) the rates of growth (that is, elongation) of the holes are high enough to make the process compatible with other processes used in the mass production of integrated circuits. In preparation for fabrication of alumina nanotemplates in this process, one first uses electron-beam evaporation to deposit thin films of titanium, followed by thin films of aluminum, on silicon wafers. Then the alumina nanotemplates are formed by anodizing the aluminum layers, as described below. In experiments in which the process was partially developed, the titanium films were 200 A thick and the aluminum films were 5 m thick. The aluminum films were oxidized to alumina, and the arrays of holes were formed by anodizing the aluminum in aqueous solutions of sulfuric and/or oxalic acid at room temperature (see figure). The diameters, spacings, and rates of growth of the holes were found to depend, variously, on the composition of the anodizing solution, the applied current, or the applied potential, as follows: In galvanostatically controlled anodizing, regardless of the

  19. Protective coating for alumina-silicon carbide whisker composites

    DOEpatents

    Tiegs, Terry N.

    1989-01-01

    Ceramic composites formed of an alumina matrix reinforced with silicon carbide whiskers homogenously dispersed therein are provided with a protective coating for preventing fracture strength degradation of the composite by oxidation during exposure to high temperatures in oxygen-containing atmospheres. The coating prevents oxidation of the silicon carbide whiskers within the matrix by sealing off the exterior of the matrix so as to prevent oxygen transport into the interior of the matrix. The coating is formed of mullite or mullite plus silicon oxide and alumina and is formed in place by heating the composite in air to a temperature greater than 1200.degree. C. This coating is less than about 100 microns thick and adequately protects the underlying composite from fracture strength degradation due to oxidation.

  20. Capillarity in isothermal infiltration of alumina fiber preforms with aluminum

    SciTech Connect

    Michaud, V.J.; Mortensen, A. . Dept. of Materials Science); Compton, L.M. )

    1994-10-01

    Models derived in petroleum engineering and soil science for flow of two immiscible fluids in a porous medium are extended to the infiltration of ceramic preforms by a liquid metal. SAFFIL alumina fiber preforms are infiltrated with an aluminum matrix in a series of interrupted unidirectional and isothermal experiments at various low applied pressures, to measure profiles of the volume fraction of metal along the length of the preforms. Comparison of experimental data with theory reveals the existence of a pressure-dependent incubation time for wetting of the alumina preforms by molten aluminum at 973 K. If this incubation time is taken into account, experimental curves of metal distribution are well predicted by theory, confirming the validity of the models after initiation of flow.

  1. Medication Adherence Pattern and Factors affecting Adherence in Helicobacter Pylori Eradication Therapy.

    PubMed

    Shakya Shrestha, S; Bhandari, M; Thapa, S R; Shrestha, R; Poudyal, R; Purbey, B; Gurung, R B

    2016-01-01

    Background Helicobacter pylori (H. pylori) infection is the most common chronic bacterial infection worldwide affecting approximately half of the world's population. A number of screening tests as well as complex multi-drug therapies are available for the detection and treatment of H. pylori infection. However, the optimum eradication rates of H. pylori infection can only be achieved if adherence to drug therapy is higher. Therefore, it is of utmost importance to determine the factors leading to poor adherence to obtain successful treatment outcomes. Objective To determine the medication adherence pattern in patients with H. pylori infection and assess the factors associated with non-adherence to the prescribed drug therapy. Method Patients meeting the inclusion criteria who were confirmed as H. pylori positive by rapid urease test (histopathology) and/ or stool antigen test and those under H. pylori eradication therapy were considered. Informed consent was taken from the patients or from the patient party in incapacitated patients. They were then interviewed using structured questionnaire. Statistical analysis was done using SPSS version 20 and a p-value < 0.05 was considered as statistically significant. Result Among the 70 participants included in this study, 57.10% (n=40) of them were males. The mean (±SD) age of the patients was 42.36 years (±17.93). Higher number (85.70% (n=60)) of the patients were adherent to the recommended medication. Forgetfulness was the reason for missing dose in a majority (80% (n=8)) of the nonadherent patients. A highly significant association (p<0.05) was observed between adherence and absence of symptomatic relief. However, there was no statistically significant association (p>0.05) between patients' adherence to gender, age, literacy, and the prescribed treatment regimen. Conclusion Majority of the patients with H. pylori infection were adherent to medication. Forgetfulness was the major reason for missing dose in the non-adherent

  2. Interfacial characterization of alumina-to-alumina joints fabricated using silver–copper–titanium interlayers

    SciTech Connect

    Lin, Kun-Lin; Singh, Mrityunjay; Asthana, Rajiv

    2014-04-01

    Two Ag–Cu–Ti interlayers with different compositions (Ag–35.3Cu–1.75Ti and Ag–26.7Cu–4.5Ti) were used to join sintered polycrystalline Al{sub 2}O{sub 3} having different amounts of porosity to investigate the effect of titanium and porosity contents on evolution of interfacial chemistry and microstructures. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) were used to characterize the interfacial microstructure. Two reaction layers, Ti{sub 2}O and Cu{sub 3}Ti{sub 3}O, were found at the interface of Ag–Cu–Ti interlayers and Al{sub 2}O{sub 3} using a series of simulated and experimental selected area diffraction patterns (SADP) of TEM and EDS. The total thickness of Ti{sub 2}O and Cu{sub 3}Ti{sub 3}O reaction layers at the interfaces increases with increasing amounts of Ti in the Ag–Cu–Ti interlayers but is independent of the porosity content in the Al{sub 2}O{sub 3}. Two possible formation mechanisms of Ti{sub 2}O and Cu{sub 3}Ti{sub 3}O reaction layers at the interface of Ag–Cu–Ti interlayers and Al{sub 2}O{sub 3} have been proposed based on the interfacial characterization performed in the present study. - Highlights: • Effect of alumina porosity and % Ti in interlayer on interface structure delineated • SEM, EDS, XRD, TEM with SADP used to delineate phases, compositions, crystallography • Ti{sub 2}O and Cu{sub 3}Ti{sub 3}O reaction layers identified and their formation mechanisms proposed.

  3. The multiple applications of hydrocyclones in alumina production

    SciTech Connect

    Oeberg, N.; Kelton, G.P.; Rawlins, C.H.

    1996-10-01

    Hydrocyclones are used in many alumina refineries to enhance efficiency. A partial list of applications includes bauxite grinding, bauxite refinement sands separations from red muds, sand washing, hydrate classification and product size control, seed size control, hydrate thickening and deliquoring, agglomeration, preferential separation/reduction of oxalates, spent liquor solids recovery, cooling tower water clean-up, and lime slurry degritting. This paper reviews these applications including viable flowsheets and operating experience; and summarizes basic hydrocyclone selection including the main factors affecting performance.

  4. Increasing productivity during grinding of high-alumina ceramics

    SciTech Connect

    Belous, K.P.; Leptukha, V.P.

    1984-01-01

    The grinding of high-alumina ceramics involves specific problems as the effectiveness of the grinding is affected by the rate of material removal to ensure high productivity, the surface roughness, and the wear of the diamond tool. This study of the cutting processes in cylindrical and internal grinding was done to determine the optimum cutting parameters and specifications of the diamond grinding wheels, and the results helped increase productivity and reduce wheel consumption.

  5. Probing the improbable: imaging carbon atoms in alumina

    SciTech Connect

    Marquis, E A; Yahia, Noor; Larson, David J.; Miller, Michael K; Todd, Richard

    2010-01-01

    Atom-probe tomography has proven very powerful to analyze the detailed structure and chemistry of metallic alloys and semiconductor structures while ceramic materials have remained outside its standard purview. In the current work, we demonstrate that bulk alumina can be quantitatively analyzed and microstructural features observed. The analysis of grain boundary carbon segregation - barely achievable by electron microscopy - opens the possibility of understanding the mechanistic effects of dopants on mechanical properties, fracture and wear properties of bulk oxides.

  6. Conditions to obtain reliable high strength alumina via centrifugal casting

    SciTech Connect

    Huisman, W.; Graule, T.; Gauckler, L.J.

    1995-09-01

    Electrostatically stabilized alumina suspensions with high solids content of up to 58 vol% were consolidated into near-net-shape parts via centrifugal casting. High density green bodies showed excellent sintering kinetics leading to {ge} 99.5% of theoretical density (TD) at lowered temperatures compared to isostatic pressing. Four point bend strengths of 540 MPa with Weibull moduli of up to 24 were achieved using commercial {alpha}-alurnina powders.

  7. Directional solidification of the alumina-zirconia ceramic eutectic system

    SciTech Connect

    Boldt, Christopher

    1994-07-27

    It is possible to produce alumina-zirconia ceramic samples through existing solidification techniques. The resulting microstructures typically consist of rods of zirconia in an alumina matrix, although a lamellar structure has been noted in some cases. In nearly all cases, colony growth was present which may possibly result from grain size, repeated nucleation events, and lamellar oscillations. In the same vein, it appears that the amount of impurities within the system might be the underlying cause for the colony growth. Colony growth was diminished through impurity control as the higher purity samples exhibited colony free behavior. In addition to colony formations, faceted alumina dendrites or nonfaceted zirconia dendrites may result in the ceramic if the sample is solidified out of the coupled zone. In all cases, for larger-sized Bridgman samples, a lower limit in the eutectic spacing was noted. The solidification model which includes the kinetic effect has been developed, although the effect appears to be negligible under present experimental conditions. A spacing limit might also occur due to the result of heat flow problems. Heat flow out of the ceramic is difficult to control, often causing radial and not axial growth. This behavior is exaggerated in the presence of impurities. Thus, higher purity powders should always be used. Higher purity samples, in addition to yielding a more microstructurally uniform ceramic, also showed increased directionality. In the future, the kinetic model needs to be examined in more detail, and further research needs to be accomplished in the area of molten ceramics. Once better system constants are in place, the kinetic model will give a better indication of the behavior in the alumina-zirconia system.

  8. Proton adsorption onto alumina: extension of multisite complexation (MUSIC) theory

    SciTech Connect

    Nagashima, K.; Blum, F.D.

    1999-09-01

    The adsorption isotherm of protons onto a commercial {gamma}-alumina sample was determined in aqueous nitric acid with sodium nitrate as a background electrolyte. Three discrete regions could be discerned in the log-log plots of the proton isotherm determined at the solution pH 5 to 2. The multisite complexation (MUSIC) model was modified to analyze the simultaneous adsorption of protons onto various kinds of surface species.

  9. Single Crystal Structure Determination of Alumina to 1 Mbar

    NASA Astrophysics Data System (ADS)

    Dong, H.; Zhang, L.; Prakapenka, V.; Mao, H.

    2014-12-01

    Aluminum oxide (Al2O3) is an important ceramic material and a major oxide in the earth. Additionally, alumina is a widely used pressure standard in static high-pressure experiments (Cr3+-bearing corundum, ruby). The changes of its crystal structure with pressure (P) and temperature (T) are important for its applications and understanding its physical properties in the deep Earth. There have been numerous reports on the high P-T polymorphs of alumina. Previous theoretical calculations and experiments suggest that the crystal structure of Al2O3 evolves greatly at high P-T. In this study, we used the newly developed multigrain crystallography method combined with single-crystal x-ray diffraction analysis technique for the structure determination of alumina at high P-T to provide single-crystal structure refinement for high-pressure phases of Al2O3. Alumina powder was mixed with ~10% Pt and Ne was used as both pressure transmitting media and thermal insulating layers during laser-heating. Coarse-grained aggregates of Al2O3 were synthesized in a laser-heated diamond anvil cell. The structure change of Al2O3 was monitored by in situ x-ray diffraction at ~1 Mbar and 2700 K. The results allow us to distinguish the structural differences between the Rh2O3 (II) structure (space group Pbcn) and perovskite structure (space group Pbnm) for the first high-pressure phase of Al2O3. More detailed results will be discussed in the later work.

  10. Advances in Zirconia Toughened Alumina Biomaterials for Total Joint Replacement

    PubMed Central

    Kurtz, Steven M.; Kocagöz, Sevi; Arnholt, Christina; Huet, Roland; Ueno, Masaru; Walter, William L.

    2014-01-01

    The objective of this article is to provide an up-to-date overview of zirconia-toughened alumina (ZTA) components used in total hip arthroplasties. The structure, mechanical properties, and available data regarding the clinical performance of ZTA are summarized. The advancements that have been made in understanding the in vivo performance of ZTA are investigated. This article concludes with a discussion of gaps in the literature related to ceramic biomaterials and avenues for future research. PMID:23746930

  11. Mechanically reliable scales and coatings

    SciTech Connect

    Tortorelli, P.F.; Alexander, K.B.

    1995-07-01

    As the first stage in examining the mechanical reliability of protective surface oxides, the behavior of alumina scales formed on iron-aluminum alloys during high-temperature cyclic oxidation was characterized in terms of damage and spallation tendencies. Scales were thermally grown on specimens of three iron-aluminum composition using a series of exposures to air at 1000{degrees}C. Gravimetric data and microscopy revealed substantially better integrity and adhesion of the scales grown on an alloy containing zirconium. The use of polished (rather than just ground) specimens resulted in scales that were more suitable for subsequent characterization of mechanical reliability.

  12. Alumina Based 500 C Electronic Packaging Systems and Future Development

    NASA Technical Reports Server (NTRS)

    Chen, Liang-Yu

    2012-01-01

    NASA space and aeronautical missions for probing the inner solar planets as well as for in situ monitoring and control of next-generation aeronautical engines require high-temperature environment operable sensors and electronics. A 96% aluminum oxide and Au thick-film metallization based packaging system including chip-level packages, printed circuit board, and edge-connector is in development for high temperature SiC electronics. An electronic packaging system based on this material system was successfully tested and demonstrated with SiC electronics at 500 C for over 10,000 hours in laboratory conditions previously. In addition to the tests in laboratory environments, this packaging system has more recently been tested with a SiC junction field effect transistor (JFET) on low earth orbit through the NASA Materials on the International Space Station Experiment 7 (MISSE7). A SiC JFET with a packaging system composed of a 96% alumina chip-level package and an alumina printed circuit board mounted on a data acquisition circuit board was launched as a part of the MISSE7 suite to International Space Station via a Shuttle mission and tested on the orbit for eighteen months. A summary of results of tests in both laboratory and space environments will be presented. The future development of alumina based high temperature packaging using co-fired material systems for improved performance at high temperature and more feasible mass production will also be discussed.

  13. Liquid permeation and chemical stability of anodic alumina membranes

    PubMed Central

    Buldakov, Dmitrii A; Tishkin, Alexey A; Lukashin, Alexey V; Eliseev, Andrei A

    2017-01-01

    A study on the chemical stability of anodic alumina membranes and their performance in long-term water and organic solvent permeation experiments is reported. Anodic alumina possesses high stability for both protonic and aprotonic organic solvents. However, serious degradation of the membrane occurs in pure water, leading to a drastic decrease of permeance (over 20% of the initial value after the passing of 0.250 m3/m2 of pure water). The drying of the membrane induces further permeance drop-off. The rate of membrane degradation strongly depends on the pH of the penetrant solution and increases in basic media. According to 27Al NMR and thermogravimetry results, the degradation of the membranes is associated with the dissolution of water-soluble [Al13O4(OH)24(H2O)12]7+ polyhydroxocomplexes and their further redeposition in the form of [Al(OH)4]−, resulting in channels blocking. This process intensifies in basic pH due to the high positive charge of the anodic alumina surface. An approach for improving anodic aluminum oxide stability towards dissolution in water by carbon CVD coating of the membrane walls is suggested. PMID:28382245

  14. Thermochemical Analysis of Molybdenum Thin Films on Porous Alumina.

    PubMed

    Lee, Kyoungjin; de Lannoy, Charles-François; Liguori, Simona; Wilcox, Jennifer

    2017-01-12

    Molybdenum (Mo) thin films (thickness <100 nm) were physically deposited by e-beam evaporation on a porous alumina substrate and were analyzed for their stability and reactivity under various thermal and gas conditions. The Mo thin-film composites were stable below 300 °C but had no reactivity toward gases. Mo thin films showed nitrogen incorporation on the surface as well as in the subsurface at 450 °C, as confirmed by X-ray photoelectron spectroscopy. The reactivity toward nitrogen was diminished in the presence of CO2, although no carbon species were detected either on the surface or in the subsurface. The Mo thin films have a very stable native oxide layer, which may further oxidize to higher oxidation states above 500 °C due to the reaction with the porous anodized alumina substrate. The oxidation of Mo thin films was accelerated in the presence of oxidizing gases. At 600 °C in N2, the Mo thin film on anodized alumina was completely oxidized and may also have been volatilized. The results imply that choosing thermally stable and inactive porous supports and operating in nonoxidizing conditions below 500 °C will likely maintain the stability of the Mo composite. This study provides key information about the chemical and structural stability of a Mo thin film on a porous substrate for future membrane applications and offers further insights into the integrity of thin-film composites when exposed to harsh conditions.

  15. EFFECT OF GRAIN SIZE ON DYNAMIC SCRATCH RESPONSE IN ALUMINA

    SciTech Connect

    Wang, Hong; Wereszczak, Andrew A; Lance, Michael J

    2006-01-01

    The machining and wear of ceramics and ceramic components are obviously influenced by abrasive damage. One parameter that can affect the abrasion process is the grain size of the ceramic material. To investigate this, single-grit pendulum scratch testing was used to investigate the dynamic scratch response in three 99.9% aluminas that each had a tight size distribution about mean grain sizes of 2, 15, or 25 m, respectively. The scratch speeds generated had an order of magnitude of ~ 1 m/s and the maximum scratch depths were several tens of micrometers. Tangential and normal scratch forces were monitored during each test and interpreted in conjunction with postmortem SEM and profilometry results. It was observed that both plastic deformation and brittle fracture participated in the scratching process and the relative activity of each was dependent on depth of penetration. At a specific depth of penetration, the material removal of alumina prevailingly relies on the generation and interaction of oblique radial and lateral cracks. Chip formation is greatly enhanced when the created cracks interact and that interaction itself depends on grain size. Larger grain size gives rise to larger lateral cracks, more severe fracture at the groove's bottom, and larger amplitude of scratch force oscillation. Lastly, the cutting pressure and the scratch hardness of alumina exhibit sensitivity to both grain size and the groove depth.

  16. Removing Bacillus subtilis from fermentation broth using alumina nanoparticles.

    PubMed

    Mu, Dashuai; Mu, Xin; Xu, Zhenxing; Du, Zongjun; Chen, Guanjun

    2015-12-01

    In this study, an efficient separation technology using Al2O3 nanoparticles (NPs) was developed for removing Bacillus subtilis from fermentation broth. The dosage of alumina nanoparticles used for separating B. subtilis increased during the culture process and remained stable in the stationary phase of the culture process. The pH of the culture-broth was also investigated for its effects on flocculation efficiency, and showed an acidic pH could enhance the flocculation efficiency. The attachment mechanisms of Al2O3 NPs to the B. subtilis surface were investigated, and the zeta potential analysis showed that Al2O3 NPs could attach to B. subtilis via electrostatic attachment. Finally, the metabolite content and the antibacterial effect of the fermentation supernatants were detected and did not significantly differ between alumina nanoparticle separation and centrifugation separation. Together, these results indicate a great potential for a highly efficient and economical method for removing B. subtilis from fermentation broth using alumina nanoparticles.

  17. Mechanics in alumina ceramics modified by ultradispersed diamonds

    NASA Astrophysics Data System (ADS)

    Kireitseu, Maksim V.; Yerakhavets, Sergey G.; Basenuk, Vladimir L.; Jornik, Victor

    2003-10-01

    Alumina coating modified by ultra-dispersed diamonds (UDD) have been produced by combination of thermal flame spraying and micro arc oxidizing technologies on sprayed aluminum substrate was. Structures of alumina-based ultra dispersed diamond particles composite coatings were investigated in detail by transmission electron microscopy and SEM imaging. The particles were deposited with alumina layer on aluminum substrates under various conditions and have different levels of strength, hardness and internal stresses. It was revealed that by UDD strengthening the coating is to have high microhardness of 22 - 26 GPa, fine structure and smooth surface. Diamonds was found to be conglomerated in clusters along the interface obtained with high current density, but it disappeared when deposited with lower current regimes of alternating pulse current. On the other hand, the failure of crystal diamonds became smaller with decreasing current density concentrations. From the correspondence between the structures and the hardness of the composite, it was suggested that the effect of ultra dispersed diamonds resulted in the complicated trend of hardness, strength and fine structure with respect to current density and diamonds concentration in the electrolyte. In view of technological setup pulse current regime at high current frequency improve microhardness and roughness of the coatings. Potential application of the coating is sliding bearings, insulators, aerospace units.

  18. Zirconia-alumina-nanodiamond composites with gemological properties

    NASA Astrophysics Data System (ADS)

    Díaz, Luis A.; Montes-Morán, Miguel A.; Peretyagin, Pavel Y.; Vladimirov, Yuriy G.; Okunkova, Anna; Moya, José S.; Torrecillas, Ramón

    2014-02-01

    Nanodiamonds have excellent mechanical and optical properties with a wide range of potential applications as a filler material for nanocomposites. Here, we present a new family of zirconia-alumina-nanodiamond composites using two main processing routes: (1) a colloidal method, and (2) power mixing homogenization. Composites with detonation nanodiamonds quantities ranging within 0.3-5 vol.% followed by a pulsed electrical current sintering at a temperature range from 1,200 to 1,500 °C have been analyzed, and a significant enhancement in mechanical properties, i.e., indentation hardness (16.17 GPa), fracture toughness (15.5 MPa m1/2), and bending strength (1,600 MPa), could be observed. To support these excellent properties, TEM, color, reflectivity, and Raman spectroscopy measurements were also carried out. The microstructure of the composites is very homogeneous with average grain sizes between 200 and 500 nm depending on the processing temperature. Two morphologies are present: (a) intergranular dispersion of alumina grains and nanodiamonds distributed along the grain boundaries of the ZrO2 matrix, and (b) intragranular nano-dispersion of ZrO2 particles with sizes 20-80 nm located inside the alumina grains. In the present article, we show, for the first time in the scientific literature, a continuous palette of gray color gradation of new ceramic materials of metalized colors (white index L* 98-40) for gemological applications.

  19. Adherence to Exercise and Physical Activity: Preface.

    ERIC Educational Resources Information Center

    Morgan, William P.; Dishman, Rod K.

    2001-01-01

    Introduces a collection of papers on adherence to exercise programs and physical activity from the 2000 American Academy of Kinesiology and Physical Education conference, which included research on middle school boys and girls, college men and women, and men and women in the later years, as well as on the more traditional subject of middle aged…

  20. Adherence to Sports-Injury Rehabilitation Programs.

    ERIC Educational Resources Information Center

    Fisher, A. Craig; And Others

    1988-01-01

    Analysis of 41 injured college athletes' responses to a questionnaire revealed that those athletes who adhered to their rehabilitation program were more self-motivated, tolerated pain better, perceived that they worked harder at their rehabilitation, and were less bothered by scheduling of sessions and athletic training environmental conditions.…

  1. E-health strategies to support adherence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adherence to healthy behaviors and self-care strategies is a concern among clinicians. E-health applications, such as the internet, personal communication devices, electronic health records and web portals, and electronic games, may be a way to provide health information in a way that is reliable, c...

  2. Funhaler spacer: improving adherence without compromising delivery

    PubMed Central

    Watt, P; Clements, B; Devadason, S; Chaney, G

    2003-01-01

    A novel asthma spacer device, the "Funhaler", incorporates incentive toys which are isolated from the main inspiratory circuit by a valve. Here we show that its use does not compromise drug delivery. Improved adherence combined with satisfactory delivery characteristics suggest that the Funhaler may be useful for management of young asthmatics. PMID:12818901

  3. Non-adherence in difficult asthma and advances in detection.

    PubMed

    Lindsay, John T; Heaney, Liam G

    2013-12-01

    Non-adherence to anti-inflammatory therapies is common in patients referred for specialist assessment at difficult-to-treat asthma services. In the difficult asthma setting, non-adherence to treatment is associated with poor baseline asthma control, increased frequency of exacerbations and asthma-related hospitalizations, as well as increased risk of death. Here, we present a review of the current literature surrounding the prevalence and risks of non-adherence in difficult asthma and we report on current methods of measuring treatment adherence and advances in the detection of non-adherence. We will also explore methods by which non-adherence in difficult asthma can be addressed.

  4. Formation process of a strong water-repellent alumina surface by the sol-gel method

    NASA Astrophysics Data System (ADS)

    Feng, Libang; Li, Hui; Song, Yongfeng; Wang, Yulong

    2010-03-01

    A novel strong water-repellent alumina thin film is fabricated by chemically adsorbing stearic acid (STA) layer onto the porous and roughened aluminum film coated with polyethyleneimine (PEI). The formation process and the structure of the strong water-repellent alumina film are investigated by means of contact angle measurement and atomic force microscope (AFM). Results show that the water contact angles for the alumina films increase with the increase of the immersion time in the boiling water, and meanwhile, the roughness of the alumina films increases with the dissolution of the boehmite in the boiling water. Finally, the strong water-repellent film with a high water contact angle of 139.1° is obtained when the alumina films have distinct roughened morphology with some papillary peaks and porous structure. Moreover, both the roughened structure and the hydrophobic materials of the STA endow the alumina films with the strong water-repellence.

  5. Role of metal oxides in chemical evolution: interaction of ribose nucleotides with alumina.

    PubMed

    Arora, Avnish Kumar; Kamaluddin

    2009-03-01

    Interaction of ribonucleotides--namely, 5'-AMP, 5'-GMP, 5'-CMP, and 5'-UMP--with acidic, neutral, and basic alumina has been studied. Purine nucleotides showed higher adsorption on alumina in comparison with pyrimidine nucleotides under acidic conditions. Adsorption data obtained followed Langmuir adsorption isotherm, and X(m) and K(L) values were calculated. On the basis of infrared spectral studies of ribonucleotides, alumina, and ribonucleotide-alumina adducts, we propose that the nitrogen base and phosphate moiety of the ribonucleotides interact with the positive charge surface of alumina. Results of the present study may indicate the importance of alumina in concentrating organic molecules from dilute aqueous solutions in primeval seas in the course of chemical evolution on Earth.

  6. The relationship between beliefs about sleep and adherence to behavioral treatment combined with meditation for insomnia.

    PubMed

    Cvengros, Jamie A; Crawford, Megan R; Manber, Rachel; Ong, Jason C

    2015-01-01

    This study examined beliefs about sleep, as measured by the Dysfunctional Beliefs and Attitudes about Sleep (DBAS) scale, as predictors of adherence to 3 specific insomnia treatment recommendations: restriction of time spent in bed, maintenance of a consistent rise time, and completion of daily meditation practice. Higher DBAS scores predicted poorer adherence to restriction of time spent in bed and to maintenance of a prescribed rise time. DBAS scores were not associated with completion of daily meditation. These preliminary findings suggest that pre-treatment beliefs about sleep may impact patient engagement with behavioral recommendations regarding time in bed and consistent rise time during treatment for insomnia.

  7. Quality of life associated with treatment adherence in patients with type 2 diabetes: a cross-sectional study

    PubMed Central

    Martínez, Yolanda V; Prado-Aguilar, Carlos A; Rascón-Pacheco, Ramón A; Valdivia-Martínez, José J

    2008-01-01

    Background Despite certain contradictions, an association has been identified between adherence to drug treatment and the quality of life in patients with type 2 diabetes. The contradictions observed emphasize the importance of using different methods to measure treatment adherence, or the association of psychological precursors of adherence with quality of life. For this reason, we have used an indirect method to measure adherence (pill count), as well as two adherence behaviour precursors (attitude and knowledge), to assess the association between adherence and the quality of life in type 2 diabetes patients. Methods A cross-sectional comparative study on a random sample of 238 type 2 diabetic patients was carried out over one year in four family medicine units of the Mexican Institute of Social Security (IMSS) in Aguascalientes, Mexico. Treatment adherence was measured using the indirect method of pill count to assess adherence behaviour, obtaining information at two home visits. In the first we recorded the medicine prescribed and in the second, we counted the medicine remaining to determine the proportion of the medicine taken. We also assessed two adherence behaviour precursors: the patients' knowledge regarding their medical prescription measured through a structured questionnaire; and attitudes to treatment adherence using a Likert scale. Quality of life was measured through the WHOQOL-100 (the WHO Quality of Life questionnaire). Information concerning both knowledge and attitude was obtained through interviews with the patients. A multiple linear regression model was constructed to establish the relationship between each quality of life domain and the variables related to adherence, controlling for covariates. Results There was no association between quality of life and treatment adherence behaviour. However, the combination of strong knowledge and a positive attitude was associated with five of the six quality of life domains. Conclusion The results

  8. IMPROVED CORROSION RESISTANCE OF ALUMINA REFRACTORIES

    SciTech Connect

    John P. Hurley; Patty L. Kleven

    2001-09-30

    The initial objective of this project was to do a literature search to define the problems of refractory selection in the metals and glass industries. The problems fall into three categories: Economic--What do the major problems cost the industries financially? Operational--How do the major problems affect production efficiency and impact the environment? and Scientific--What are the chemical and physical mechanisms that cause the problems to occur? This report presents a summary of these problems. It was used to determine the areas in which the EERC can provide the most assistance through bench-scale and laboratory testing. The final objective of this project was to design and build a bench-scale high-temperature controlled atmosphere dynamic corrosion application furnace (CADCAF). The furnace will be used to evaluate refractory test samples in the presence of flowing corrodents for extended periods, to temperatures of 1600 C under controlled atmospheres. Corrodents will include molten slag, steel, and glass. This test should prove useful for the glass and steel industries when faced with the decision of choosing the best refractory for flowing corrodent conditions.

  9. Reported Racial Discrimination, Trust in Physicians, and Medication Adherence Among Inner-City African Americans With Hypertension

    PubMed Central

    Hargraves, J. Lee; Rosal, Milagros; Briesacher, Becky A.; Schoenthaler, Antoinette; Person, Sharina; Hullett, Sandral; Allison, Jeroan

    2013-01-01

    Objectives. We sought to determine if reported racial discrimination was associated with medication nonadherence among African Americans with hypertension and if distrust of physicians was a contributing factor. Methods. Data were obtained from the TRUST project conducted in Birmingham, Alabama, 2006 to 2008. All participants were African Americans diagnosed with hypertension and receiving care at an inner city, safety net setting. Three categories of increasing adherence were defined based on the Morisky Medication Adherence Scale. Trust in physicians was measured with the Hall General Trust Scale, and discrimination was measured with the Experiences of Discrimination Scale. Associations were quantified by ordinal logistic regression, adjusting for gender, age, education, and income. Results. The analytic sample consisted of 227 African American men and 553 African American women, with a mean age of 53.7 ±9.9 years. Mean discrimination scores decreased monotonically across increasing category of medication adherence (4.1, 3.6, 2.9; P = .025), though the opposite was found for trust scores (36.5, 38.5, 40.8; P < .001). Trust mediated 39% (95% confidence interval = 17%, 100%) of the association between discrimination and medication adherence. Conclusions. Within our sample of inner city African Americans with hypertension, racial discrimination was associated with lower medication adherence, and this association was partially mediated by trust in physicians. Patient, physician and system approaches to increase “earned” trust may enhance existing interventions for promoting medication adherence. PMID:24028222

  10. Bacterial adherence to anodized titanium alloy

    NASA Astrophysics Data System (ADS)

    Pérez-Jorge Peremarch, C.; Pérez Tanoira, R.; Arenas, M. A.; Matykina, E.; Conde, A.; De Damborenea, J. J.; Gómez Barrena, E.; Esteban, J.

    2010-11-01

    The aim of this study was to evaluate Staphylococcus sp adhesion to modified surfaces of anodized titanium alloy (Ti-6Al-4V). Surface modification involved generation of fluoride-containing titanium oxide nanotube films. Specimens of Ti-6Al-4V alloy 6-4 ELI-grade 23- meets the requirements of ASTM F136 2002A (AMS 2631B class A1) were anodized in a mixture of sulphuric/hydrofluoric acid at 20 V for 5 and 60 min to form a 100 nm-thick porous film of 20 nm pore diameter and 230 nm-thick nanotube films of 100 nm in diameter. The amount of fluorine in the oxide films was of 6% and of 4%, respectively. Collection strains and six clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis were studied. The adherence study was performed using a previously published protocol by Kinnari et al. The experiments were performed in triplicates. As a result, lower adherence was detected for collection strains in modified materials than in unmodified controls. Differences between clinical strains were detected for both species (p<0.0001, Kruskal-Wallis test), although global data showed similar results to that of collection strains (p<0.0001, Kruskal-Wallis test). Adherence of bacteria to modified surfaces was decreased for both species. The results also reflect a difference in the adherence between S. aureus and S. epidermidis to the modified material. As a conclusion, not only we were able to confirm the decrease of adherence in the modified surface, but also the need to test multiple clinical strains to obtain more realistic microbiological results due to intraspecies differences.

  11. Divalent Beta’ Aluminas: High Conductivity Solid Electrolytes for Divalent Cations.

    DTIC Science & Technology

    1982-10-13

    results indicated that divalent ions diffuse very slowly in beta alumina, they discouraged interest in its divalent derivatives. After their work...using polycrystalline Na+ beta alumina to separate two NiCl2-NaCl melts at 800-10000C. After several days’ exposure, they found that the beta alumina...samples were exchanged in a nitrogen or argon atmosphere. After exchange, crystals were soaked in a suitable solvent (usually methanol), washed in

  12. Lifetime of Sodium Beta-Alumina Membranes in Molten Sodium Hydroxide

    DTIC Science & Technology

    2008-07-01

    Report 3. DATES COVERED (From – To) 1 April 2007 – 01 April 2008 4. TITLE AND SUBTITLE Lifetime of Sodium Beta-alumina Membranes in Molten Sodium ...ABSTRACT Summary: Sodium metal can be made by electrolysis of molten sodium hydroxide in sodium beta-alumina membrane electrolysis cells...However, there are some uncertainties about the lifetime of the sodium beta-alumina membranes in contact with molten sodium hydroxide. The main objective

  13. The Effect of Alumina Dispersant Powder on the Workability of Chromia Based Refractory for IGCC Application

    NASA Astrophysics Data System (ADS)

    Ming, Zhao Jing; Xun, Yang Zheng; Hong, Hwang Kyu; Hwan, Park Sang

    2011-10-01

    The quality of refractory applied on IGCC is a key factor that affects the cost of production. The workability and microstructure of chromia based castable are varied by introducing different type of alumina dispersant powder, such as active alumina powder. In this study, three types of active alumina powder are added to improve the workability. It's proved that the specific surface area and particle size distribution of fine powders in matrix part greatly affect the flow values and microstructures.

  14. Structural and Acidic Properties of Niobia-Silica and Niobia-Alumina Aerogels

    DTIC Science & Technology

    1991-05-06

    objective is to develop a comparative set of samples of known structure for chemical characterization . Bulk oxide aerogels of niobia, alumina, and silica ...objective is to develop a comparative set of samples of known structure for chemical characterization . Bulk oxide aerogels of niobia, alumina, and silica were...properties and the developed structures caused by the thermal treatment or increased concentration of niobia on the silica and alumina aerogel

  15. Variation in medication adherence across patient behavioral segments: a multi-country study in hypertension

    PubMed Central

    Sandy, Robert; Connor, Ulla

    2015-01-01

    Objectives This study determines the following for a hypertensive patient population: 1) the prevalence of patient worldview clusters; 2) differences in medication adherence across these clusters; and 3) the adherence predictive power of the clusters relative to measures of patients’ concerns over their medication’s cost, side effects, and efficacy. Methods Members from patient panels in the UK, Germany, Italy, and Spain were invited to participate in an online survey that included the Medication Adherence Report Scale-5 (MARS-5) adherence instrument and a patient segmentation instrument developed by CoMac Analytics, Inc, based on a linguistic analysis of patient talk. Subjects were screened to have a diagnosis of hypertension and treatment with at least one antihypertensive agent. Results A total of 353 patients completed the online survey in August/September 2011 and were categorized against three different behavioral domains: 1) control orientation (n=176 respondents [50%] for I, internal; n=177 respondents [50%] for E, external); 2) emotion (n=100 respondents [28%] for P, positive; n=253 respondents [72%] for N, negative); and 3) agency or ability to act on choices (n=227 respondents [64%] for H, high agency; n=126 [36%] for L, low agency). Domains were grouped into eight different clusters with EPH and IPH being the most prevalent (88 respondents [25%] in each cluster). The prevalence of other behavior clusters ranged from 6% (22 respondents, INH) to 12% (41 respondents, IPL). The proportion of patients defined as perfectly adherent (scored 25 on MARS-5) varied sharply across the segments: 51% adherent (45 of 88 respondents) for the IPH vs 8% adherent (2 of 25 respondents) classified as INL. Side effects, being employed, and stopping medicine because the patient got better were all significant determinants of adherence in a probit regression model. Conclusion By categorizing patients into worldview clusters, we identified wide differences in adherence that

  16. Adherence and Patients' Experiences with the Use of Capecitabine in Daily Practice

    PubMed Central

    Timmers, Lonneke; Boons, Christel C. L. M.; Mangnus, Dirk; Van de Ven, Peter M.; Van den Berg, Pieter H.; Beeker, Aart; Swart, Eleonora L.; Honeywell, Richard J.; Peters, Godefridus J.; Boven, Epie; Hugtenburg, Jacqueline G.

    2016-01-01

    Introduction: Capecitabine is a widely prescribed oral anticancer agent. We studied medication adherence and explored its use in daily practice from a patients' perspective. Patients and Methods: Patients (n = 92) starting capecitabine were followed up to five 3-week cycles. Adherence was assessed using a pill count, pharmacy data and dosing information from the patients' medical file. Self-reported adherence was measured using the Medication Adherence Report Scale (MARS). At baseline and during week 2 of cycles 1, 3, and 5, patients filled out questionnaires about quality of life, symptoms, attitude toward medicines and disease and use in daily practice. Simultaneously, blood samples were taken to determine the area under the curve (AUC) of 5′-deoxy-5-fluorouridine (5′-DFUR), 5-fluorouracil (5-FU), and α-fluoro-β-alanine (FBAL) by a population pharmacokinetic model. Associations between AUCs and patient-reported symptoms were tested for cycles 3 and 5. Results: Most patients (84/92; 91%) had an adherence rate of ≥95 and ≤ 105%. The percentage of patients reporting any non-adherence behavior measured with MARS increased from 16% at cycle 1 to 29% at cycle 5. Symptoms were reported frequently and the dosing regimen was adjusted by the physician at least once in 62% of patients. In multivariate analysis the probability of an adjustment increased with the number of co-medication (OR 1.19, 95% CI: 1.03–1.39) and a stronger emotional response to the disease (OR 1.32, 95% CI: 1.10–1.59). The AUC of 5′-DFUR was associated with weight loss (OR 1.10, 95% CI: 1.01–1.19), AUC of FBAL with hand-foot syndrome (OR 0.90, 95% CI: 0.83–0.99), rhinorrhea (OR 1.21, 95% CI: 1.03–1.42 weight loss (OR 1.09, 95% CI: 1.00–1.20) and depression (OR 0.90, 95% CI: 0.82–0.99). Side effects were reported by one third of patients as the reason to discontinue treatment. Conclusion: Adherence to capecitabine was generally high. Nevertheless, adherence measured with MARS

  17. Adherence to treatment in patients with open-angle glaucoma and its related factors

    PubMed Central

    Movahedinejad, Tayebeh; Adib-Hajbaghery, Mohsen

    2016-01-01

    Introduction Lack of adherence to medical treatments typically lead to burdensome consequences such as progressive visual impairment, blindness, and disabilities. This study aimed to determine the adherence to medication in patients with open-angle glaucoma and related factors in patients referred to the Matini Ophthalmology Hospital in Kashan, Iran. Methods A cross-sectional study was conducted from 23 July 2015 to 20 January 2016 on all patients with open-angle glaucoma referred to the Matini Ophthalmology Hospital in Kashan, Iran. A questionnaire was used to gather data about patients’ demographics and factors affecting adherence to medical treatments. The Morisky Medication Adherence Scale was used to evaluate the adherence to glaucoma medication. Results were analyzed using SPSS version 13. Descriptive statistics, chi-square, and logistic regression analysis were used. Results In total, 130 patients with a mean age of 55.36 ± 15.54 were studied. Only 34.6% of patients completely adhered to glaucoma medications. The chi-square test showed that age (p=0.007), education (p=0.01), life entourage (p=0.04), place of residence (p=0.06), average monthly income (p=0.005), the interval between medical visits (p=0.007), problem in scheduling the medical visits (p<0.001), number of medications (p<0.001), lifelong using and side-effects of medications (p<0.001), answers of the physician to the patient’s questions (p<0.001), financial and traveling problems (p<0.001), lack of skill in using eye drops (p<0.001), lack of awareness of glaucoma complications and symptoms (p<0.001), forgetting, fatigue, impatience, believing in uselessness of medications, and lack of support from family (p<0.001) were associated with patients’ adherence. Logistic regression showed that 89% of variance of patients’ adherence to glaucoma medications can be predicted by seven factors: problems in traveling and scheduling medical visits, the large number and side effects of medications

  18. Adherence to the oral contraceptive pill: a cross-sectional survey of modifiable behavioural determinants

    PubMed Central

    2012-01-01

    Background Poor adherence to the oral contraceptive pill (OCP) is reported as one of the main causes of unintended pregnancy in women that rely on this form of contraception. This study aims to estimate the associations between a range of well-established modifiable psychological factors and adherence to OCP. Method A cross-sectional survey of 130 female University students currently using OCP (Mean age: 20.46 SD: 3.01, range 17–36) was conducted. An OCP specific Medication Adherence Report Scale was used to assess non-adherence. Psychological predictor measures included necessity and concern beliefs about OCP, intentions, perceived behavioural control (pbc), anticipated regret and action and coping planning. Multiple linear regression was used to analyse the data. Results Fifty-two per cent of participants reported missing their OCP once or more per month and 14% twice or more per month. In bivariate analysis intentions (r = −0.25), perceived behavioural control (r= −0.66), anticipated regret (r=0.20), concerns about OCP (r =0.31), and action (r= −0.25) and coping (r= −0.28) planning were all significantly associated with adherence to OCP in the predicted direction. In a multivariate model almost half (48%) of the variation in OCP adherence could be explained. The strongest and only statistically significant predictors in this model were perceived behavioural control (β=−0.62, p<0.01) and coping planning (β =−0.23, p=0.03). A significant interaction between intentions and anticipated regret was also observed. Conclusion The present data point to a number of key modifiable psychological determinants of OCP use. Future work will establish whether changing these variables results in better adherence to the OCP. PMID:23031437

  19. Adherent Use of Digital Health Trackers Is Associated with Weight Loss.

    PubMed

    Pourzanjani, Arya; Quisel, Tom; Foschini, Luca

    2016-01-01

    We study the association between weight fluctuation and activity tracking in an on-line population of thousands of individuals using digital health trackers (1,749 ≤ N ≤ 14,411, depending on the activity tracker considered) with millions of recorded activities (119,292 ≤ N ≤ 2,221,382) over the years 2013-2015. In a first between-subject analysis, we found a positive association between activity tracking frequency and weight loss. Users who log food with moderate frequency lost an additional 0.63% (CI [0.55, 0.72]; p < .001) of their body weight per month relative to low frequency loggers. Frequent workout loggers lost an additional 0.38% (CI [0.20, 0.56]; p < .001) and frequent weight loggers lost an additional 0.40% (CI [0.33, 0.47]; p < .001) as compared to infrequent loggers. In a subsequent within-subject analysis on a subset of the population (799 ≤ N ≤ 6,052) with sufficient longitudinal data, we used fixed effect models to explore the temporal relationship between a change in tracking adherence and weight change. We found that for the same individual, weight loss is significantly higher during periods of high adherence to tracking vs. periods of low adherence: +2.74% of body weight lost per month (CI [2.68, 2.81]; p < .001) during adherent weight tracking, +1.35% per month (CI [1.26, 1.43]; p < .001) during adherent food tracking, and +0.60% per month (CI [0.44, 0.76]; p < .001) during adherent workout tracking. The findings suggest that adherence to activity tracking can be utilized as a convenient real-time predictor of weight fluctuations, enabling large-scale, personalized intervention strategies.

  20. Effects of particle size and coating on decomposition of alumina-extracted residue from high-alumina fly ash.

    PubMed

    Wang, Zehua; Ma, Shuhua; Tang, Zhenhua; Wang, Xiaohui; Zheng, Shili

    2016-05-05

    The effective removal of alkali in the alumina-extracted reside (AER) obtained by extracting alumina from high-alumina fly ash is the premise for realizing the utilization of the silicon component in the fly ash. Sodium was removed from the AER by a decomposition reaction. The effects of the particle size and reactant coating on the decomposition reaction of AER were studied, and the results showed that by decreasing the particle size, the decomposition reaction rate of AER could be enhanced obviously and the Na2O content of the products could be decreased effectively. In addition, the process and mechanism of the decomposition reaction of AER and the reaction kinetics were investigated. The results revealed that the decomposition reaction of AER started from the outer surface of the AER particles. The reaction kinetics corresponded with shrinking unreacted core models. Furthermore, the decomposition reaction rate of AER could be enhanced obviously by decreasing the particle size because the effect of product layer diffusion was weakened when the particle size of AER was decreased.

  1. Medication adherence and quality of life among the elderly with diabetic retinopathy 1

    PubMed Central

    Jannuzzi, Fernanda Freire; Cintra, Fernanda Aparecida; Rodrigues, Roberta Cunha Matheus; São-João, Thaís Moreira; Gallani, Maria Cecília Bueno Jayme

    2014-01-01

    OBJECTIVE: to investigate the factors related to medication adherence and its relation to Health- Related Quality of Life (HRQoL) in elderly people with diabetic retinopathy. METHOD: one hundred (n=100) elderly outpatients with diabetic retinopathy taking antihypertensives and/or oral antidiabetics/insulin were interviewed. Adherence was evaluated by the adherence proportion and its association with the care taken in administrating medications and by the Morisky Scale. The National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) was used to evaluate HRQoL. RESULTS: most (58%) reported the use of 80% or more of the prescribed dose and care in utilizing the medication. The item "stopping the drug when experiencing an adverse event", from the Morisky Scale, explained 12.8% and 13.5% of the variability of adherence proportion to antihypertensives and oral antidiabetics/insulin, respectively. CONCLUSION: there was better HRQoL in the Color Vision, Driving and Social Functioning domains of the NEI VFQ-25. Individuals with lower scores on the NEI VFQ-25 and higher scores on the Morisky Scale presented greater chance to be nonadherent to the pharmacological treatment of diabetes and hypertension. PMID:25591084

  2. Viscosity of aqueous and cyanate ester suspensions containing alumina nanoparticles

    SciTech Connect

    Lawler, Katherine

    2009-01-01

    The viscosities of both aqueous and cyanate ester monomer (BECy) based suspensions of alumina nanoparticle were studied. The applications for these suspensions are different: aqueous suspensions of alumina nanoparticles are used in the production of technical ceramics made by slip casting or tape casting, and the BECy based suspensions are being developed for use in an injection-type composite repair resin. In the case of aqueous suspensions, it is advantageous to achieve a high solids content with low viscosity in order to produce a high quality product. The addition of a dispersant is useful so that higher solids content suspensions can be used with lower viscosities. For BECy suspensions, the addition of nanoparticles to the BECy resin is expected to enhance the mechanical properties of the cured composite. The addition of saccharides to aqueous suspensions leads to viscosity reduction. Through DSC measurements it was found that the saccharide molecules formed a solution with water and this resulted in lowering the melting temperature of the free water according to classic freezing point depression. Saccharides also lowered the melting temperature of the bound water, but this followed a different rule. The shear thinning and melting behaviors of the suspensions were used to develop a model based on fractal-type agglomeration. It is believed that the structure of the particle flocs in these suspensions changes with the addition of saccharides which leads to the resultant viscosity decrease. The viscosity of the BECy suspensions increased with solids content, and the viscosity increase was greater than predicted by the classical Einstein equation for dilute suspensions. Instead, the Mooney equation fits the viscosity behavior well from 0-20 vol% solids. The viscosity reduction achieved at high particle loadings by the addition of benzoic acid was also investigated by NMR. It appears that the benzoic acid interacts with the surface of the alumina particle which may

  3. Oxidation behavior in reaction-bonded aluminum-silicon alloy/alumina powder compacts

    SciTech Connect

    Yokota, S.H.

    1992-12-01

    Goal of this research is to determine the feasibility of producing low-shrinkage mullite/alumina composites by applying the reaction-bonded alumina (RBAO) process to an aluminum-silicon alloy/alumina system. Mirostructural and compositional changes during heat treatment were studied by removing samples from the furnace at different steps in the heating schedule and then using optical and scanning electron microscopy, EDS and XRD to characterize the powder compacts. Results suggest that the oxidation behavior of the alloy compact is different from the model proposed for the pure Al/alumina system.

  4. Method to produce alumina aerogels having porosities greater than 80 percent

    DOEpatents

    Poco, John F.; Hrubesh, Lawrence W.

    2003-09-16

    A two-step method for producing monolithic alumina aerogels having porosities of greater than 80 percent. Very strong, very low density alumina aerogel monoliths are prepared using the two-step sol-gel process. The method of preparing pure alumina aerogel modifies the prior known sol method by combining the use of substoichiometric water for hydrolysis, the use of acetic acid to control hydrolysis/condensation, and high temperature supercritical drying, all of which contribute to the formation of a polycrystalline aerogel microstructure. This structure provides exceptional mechanical properties of the alumina aerogel, as well as enhanced thermal resistance and high temperature stability.

  5. The Effect of Novel Synthetic Methods and Parameters Control on Morphology of Nano-alumina Particles

    NASA Astrophysics Data System (ADS)

    Xie, Yadian; Kocaefe, Duygu; Kocaefe, Yasar; Cheng, Johnathan; Liu, Wei

    2016-05-01

    Alumina is an inorganic material, which is widely used in ceramics, catalysts, catalyst supports, ion exchange and other fields. The micromorphology of alumina determines its application in high tech and value-added industry and its development prospects. This paper gives an overview of the liquid phase synthetic method of alumina preparation, combined with the mechanism of its action. The present work focuses on the effects of various factors such as concentration, temperature, pH, additives, reaction system and methods of calcination on the morphology of alumina during its preparation.

  6. Electromotive force measurements on cells involving beta-alumina solid electrolyte

    NASA Technical Reports Server (NTRS)

    Choudhury, N.

    1973-01-01

    Open circuit emf measurements have been made to demonstrate that a two-phase, polycrystalline mixture of beta- alumina and alpha-alumina could be used as a solid electrolyte in galvanic cells with reversible electrodes fixing oxygen or aluminum chemical potentials. These measurements indicate that such a two phase solid electrolyte can be used to monitor oxygen chemical potentials as low as that corresponding to Al, Al2O3 coexistence. The activity of Na2O in beta-alumina in coexistence with alpha-alumina was also determined by emf measurements.

  7. RMAIS: RFID-based medication Adherence Intelligence System.

    PubMed

    McCall, Corey; Maynes, Branden; Zou, Cliff C; Zhang, Ning J

    2010-01-01

    There has been compelling evidence that outpatients, especially those who are elderly or taking multiple complexly scheduled drugs, are not taking their medicines as directed, leading to unnecessary disease progression, complications, functional disabilities, lower quality of life, and even mortality. Existing technologies for monitoring and improving drug adherence are either costly or too complicated for general patients to use. In this paper, we introduce the detailed design and the complete prototype of a marketable Radio-Frequency Identification (RFID)-based Medication Adherence Intelligence System (RMAIS) that can be conveniently used at a residential home by ordinary patients. RMAIS is designed to maintain patients' independence and enable them to take multiple daily medicine dosages of the right amount at the right time. The system is patient-centered and user-friendly by reminding a patient of the prescribed time for medication and dispensing it in a fully automatic and fool-proof way. This is achieved mainly due to its novel design of a motorized rotation platform and the smooth integration of a scale, an RFID reader, and the rotation platform. In addition, this system has an Internet-based notification function that is used to alert the patient when it is time to take medicine as well as report deviations from the prescribed schedule to the primary care physicians or pharmacists.

  8. Using communication skills to improve adherence in children with chronic disease: the adherence equation.

    PubMed

    Brand, Paul L P; Klok, Ted; Kaptein, Adrian A

    2013-12-01

    Nonadherence to maintenance medication is common in paediatric chronic conditions. Despite the common belief that nonadherence is therapy-resistant, and the apparent lack of evidence for successful interventions to improve adherence, there is, in fact, a considerable body of evidence suggesting that adherence can be improved by applying specific communicative consultation skills. These can be summarized as the adherence equation: adherence=follow-up+dialogue+barriers and beliefs+empathy and education => concordance. Close follow-up of children with a chronic condition is needed to establish a therapeutic partnership with the family. Teaching self management skills is not a unidirectional process of providing information, but requires a constructive and collaborative dialogue between the medical team and the family. Identifying barriers to adherence can be achieved in a non-confrontational manner, by showing a genuine interest what the patient's views and preferences are. In particular, parental illness perceptions and medication beliefs should be identified, because they are strong drivers of nonadherence. Through empathic evidence-based education, such perceptions and beliefs can be modified. By applying these strategies, concordance between the child's family and the medical team can be achieved, resulting in optimal adherence to the jointly created treatment plan.

  9. Bariatric Surgery Patients' Perceptions of Weight-Related Stigma in Healthcare Settings Impair Post-surgery Dietary Adherence

    PubMed Central

    Raves, Danielle M.; Brewis, Alexandra; Trainer, Sarah; Han, Seung-Yong; Wutich, Amber

    2016-01-01

    Background: Weight-related stigma is reported frequently by higher body-weight patients in healthcare settings. Bariatric surgery triggers profound weight loss. This weight loss may therefore alleviate patients' experiences of weight-related stigma within healthcare settings. In non-clinical settings, weight-related stigma is associated with weight-inducing eating patterns. Dietary adherence is a major challenge after bariatric surgery. Objectives: (1) Evaluate the relationship between weight-related stigma and post-surgical dietary adherence; (2) understand if weight loss reduces weight-related stigma, thereby improving post-surgical dietary adherence; and (3) explore provider and patient perspectives on adherence and stigma in healthcare settings. Design: This mixed methods study contrasts survey responses from 300 postoperative bariatric patients with ethnographic data based on interviews with 35 patients and extensive multi-year participant-observation within a clinic setting. The survey measured experiences of weight-related stigma, including from healthcare professionals, on the Interpersonal Sources of Weight Stigma scale and internalized stigma based on the Weight Bias Internalization Scale. Dietary adherence measures included patient self-reports, non-disordered eating patterns reported on the Disordered Eating after Bariatric Surgery scale, and food frequencies. Regression was used to assess the relationships among post-surgical stigma, dietary adherence, and weight loss. Qualitative analyses consisted of thematic analysis. Results: The quantitative data show that internalized stigma and general experiences of weight-related stigma predict worse dietary adherence, even after weight is lost. The qualitative data show patients did not generally recognize this connection, and health professionals explained it as poor patient compliance. Conclusion: Reducing perceptions of weight-related stigma in healthcare settings and weight bias internalization could

  10. Treatment Adherence in Adolescents With Inflammatory Bowel Disease: The Collective Impact of Barriers to Adherence and Anxiety/Depressive Symptoms

    PubMed Central

    Gray, Wendy N.; Denson, Lee A.; Baldassano, Robert N.

    2012-01-01

    Objective Knowledge of factors impacting adolescents’ ability to adhere to their inflammatory bowel disease (IBD) regimen is limited. The current study examines the collective impact of barriers to adherence and anxiety/depressive symptoms on adolescent adherence to the IBD regimen. Methods Adolescents (n = 79) completed measures of barriers to adherence, adherence, and anxiety/depressive symptoms at one of two specialty pediatric IBD clinics. Results Most adolescents reported barriers to adherence and 1 in 8 reported borderline or clinically elevated levels of anxiety/depressive symptoms. Anxiety/depressive symptoms moderated the relationship between barriers to adherence and adherence. Post hoc probing revealed a significant, additive effect of higher anxiety/depressive symptoms in the barriers–adherence relationship, with adherence significantly lower among adolescents with higher barriers and higher anxiety/depressive symptoms. Conclusions In order to optimize adherence in adolescents, interventions should target not only barriers to adherence but also any anxiety/depressive symptoms that may negatively impact efforts to adhere to recommended treatment. PMID:22080456

  11. The role of the affective temperament in the treatment adherence in psychiatry

    PubMed Central

    Bahrini, Lilia; Damak, Rahma; Cheour, Mejda

    2016-01-01

    Introduction Adherence to psychotropic medications is affected by factors related to the treatment, to the physician, to the environment and to the patient himself. The purpose of the present study was to investigate the influence of affective temperaments on treatment adherence. Methods Thirty six stabilized outpatients were recruited from the aftercare consultation of Psychiatry to perform Temperament Evaluation of Memphis, Pisa, Paris and San Diego Auto questionnaire version (TEMPS-A) for affective temperaments and the Medication Adherence Rating Scale (MARS) for treatment adherence. Results The total MARS score was negatively correlated with the irritable temperament score. The MARS’s score relative to the attitude of patients to psychotropic medications and their negative side effects was negatively correlated with the cyclothymic, the irritable and anxious temperaments. Patients having a diagnosis of psychotic disorder had a significantly greater medication adherence and behaviour toward medication score compared to those having a diagnosis of affective disorder. A greater MARS’s score for the negative side effects and attitudes to psychotropic medication was associated with medication by neuroleptics with prolonged action. Conclusion The results of the present study suggest that patients with irritable temperament may have more difficult to follow psychotropic medications, and that patients with cyclothymic, irritable and anxious temperaments may be more attentive and sensitive toward psychotropic medications and their negative side effects. PMID:28154695

  12. Alumina-alumina artificial hip joints. Part II: characterisation of the wear debris from in vitro hip joint simulations.

    PubMed

    Tipper, J L; Hatton, A; Nevelos, J E; Ingham, E; Doyle, C; Streicher, R; Nevelos, A B; Fisher, J

    2002-08-01

    Until recently it was not possible to reproduce clinically relevant wear rates and wear patterns in in vitro hip joint simulators for alumina ceramic-on-ceramic hip prostheses. The introduction of microseparation of the prosthesis components into in vitro wear simulations produced clinically relevant wear rates and wear patterns for the first time. The aim of this study was to characterise the wear particles generated from standard simulator testing and microseparation simulator testing of hot isostatically pressed (HIPed) and non-HIPed alumina ceramic-on-ceramic hip prostheses, and compare these particles to those generated in vivo. Standard simulation conditions produced wear rates of approximately 0.1 mm3 per million cycles for both material types. No change in surface roughness was detected and very few wear features were observed. In contrast, when microseparation was introduced into the wear simulation, wear rates of between 1.24 (HIPed) and 1.74 mm3 per million cycles (non-HIPed) were produced. Surface roughness increased and a wear stripe often observed clinically on retrieved femoral heads was also reproduced. Under standard simulation conditions only nanometre-sized wear particles (2-27.5 nm) were observed by TEM, and it was thought likely that these particles resulted from relief polishing of the alumina ceramic. However, when microseparation of the prosthesis components was introduced into the simulation, a bi-modal distribution of particle sizes was observed. The nanometre-sized particles produced by relief polishing were present (1-35nm). however, larger micrometre-sized particles were also observed by both transmission electron microscopy (TEM) (0.021 microm) and scanning electron microscopy (SEM) (0.05-->10 microm). These larger particles were thought to originate from the wear stripe and were produced by trans-granular fracture of the alumina ceramic. In Part I of this study, alumina ceramic wear particles were isolated from the periprosthetic

  13. Relationship between patients’ knowledge and medication adherence among patients with hypertension

    PubMed Central

    Jankowska-Polańska, Beata; Uchmanowicz, Izabella; Dudek, Krzysztof; Mazur, Grzegorz

    2016-01-01

    Objective The purpose of this study was to investigate the relationship between knowledge on arterial hypertension (AH) and its management, and adherence to pharmaceutical treatment. Methods The study included 233 patients diagnosed with AH and treated with hypotensive drugs for at least 1 year. The 8-item © Morisky Medication Adherence Scale (MMAS-8) and the Hypertension Knowledge-Level Scale (HK-LS) were used. Results Sixty-three percent of the patients had a low level of knowledge on AH, with the smallest proportion of correct answers provided for items related to non-pharmaceutical treatment, diet, hypertension definition, and drug adherence. When compared to patients with a high level of knowledge, those with a low knowledge had lower scores in the MMAS (6.45±1.45 vs 7.08±1.04; P=0.038). Multiple-factor analysis showed that statistically significant independent determinants of good adherence included a high level of knowledge (β=0.208; P=0.001), non-pharmaceutical treatment (β=0.182; P=0.006), and frequent blood pressure measurements (β=0.183; P=0.004). The most significant factor in MMAS was knowledge in the “drug adherence” domain (ρ=0.303; P<0.001). Conclusion Patients’ knowledge on hypertension is a significant independent determinant of good adherence. Other independent determinants include non-pharmaceutical treatment and regular blood pressure measurements. Implication for practice The identification of knowledge deficits as a factor contributing to lack of adherence and poor hypertension control remains a key challenge for multidisciplinary team caring for patients with hypertension. PMID:27994443

  14. Effect of a clinic-wide social marketing campaign to improve adherence to antiretroviral therapy for HIV infection

    PubMed Central

    Giordano, Thomas P.; Rodriguez, Sonia; Zhang, Hong; Kallen, Michael A.; Jibaja-Weiss, Maria; Buscher, April L.; Arya, Monisha; Suarez-Almazor, Maria E.; Ross, Michael

    2012-01-01

    This demonstration study tested the impact of a 5-month clinic-wide social marketing campaign at improving adherence to antiretroviral therapy (ART). The intervention included a video, posters, pens, mugs, and lapel buttons with the campaign slogan “Live the Solution: Take Your Pills Every Day.” Participants self-reported adherence over a 4-week interval, the primary outcome, with a visual analogue scale. Pre- and post-intervention surveys were completed by 141 participants. Adherence did not change over time (absolute mean change −2.02%, paired t-test p=0.39). Among the 39.7% of participants who correctly identified the campaign slogan on the post-intervention survey, adherence increased by 3.3%, while it decreased in the other participants by 5.5% (paired t-test p=0.07). The well-received campaign did not increase short-term adherence to ART, but adherence tended to increase in participants who were more engaged with the intervention. Future interventions should engage patients more completely and have a more potent effect on adherence. PMID:22983536

  15. Role of Hf4+ Doping on Oxygen Grain Boundary Diffusion in Alumina

    NASA Astrophysics Data System (ADS)

    Wu, Qian

    The growth of protective alumina scales in Al2O3-forming alloys can be affected by the addition of reactive elements, such as Hf 4+, which has been considered one of the most effective dopants to slow down the scale growth rate. While a number of theories concerning the "reactive element effect" have been proposed, a full explanation of this phenomenon is not yet available. The overall objective for this study was to conduct a systematic series of model experiments in order to elucidate the effect of HfO2 on oxygen grain boundary transport in alumina. The key questions to focus in the current work are: How do the doping levels of HfO 2 / oxidizing temperature affect oxygen grain boundary diffusion in alumina? First part of this work investigated the effect of doping levels of HfO 2 on oxygen grain boundary transport in alumina, which contains uniformly distributed Ni metallic particles. The doping levels spanned the solubility limit ranging from 100ppm to 2000ppm. The plot of the ratio kundoped/kdoped (grain-size corrected) as a function of dopant level clearly shows two behavior regimes: namely a regime I that encompasses doping levels below and near the solubility limit and a regime II where second-phase HfO2 particles were well present in the microstructure. A clearer understanding of the influence of HfO2 doping on the transport behavior can be achieved by plotting the data with respect to the fractional grain boundary coverage (f), as opposed to overall HfO2 content. The linear relationship can be rationalized with a site-blocking model, in which the Hf4+ ions obstruct the diffusive paths at the grain boundary. The second part of the work is focused on the temperature dependence of the oxidation kinetics in HfO2 doped Al2O3. The activation energy and rate constant ratio plot from our work and alloys studies indicated that multiple diffusion mechanisms might be operative at grain boundaries owing to boundary transitions that modify local structure and chemistry

  16. Measuring Adherence to Practice Guidelines for the Management of Hypertension

    PubMed Central

    Milchak, Jessica L.; Carter, Barry L.; Ardery, Gail; James, Paul A.

    2006-01-01

    Adherence to practice guidelines is frequently used as a measure of quality of care. Numerous studies have evaluated physician adherence to hypertension guidelines by prescription data, physician survey data, or medical record review. However, most have methodological limitations that might underestimate physician adherence. Accurate and meaningful characterization of adherence rests on evaluation of varied components of hypertension care, use of explicit validated performance measures, incorporation of implicit and explicit review, and linkage of process measures to blood pressure outcomes. PMID:15381676

  17. Improved assay for quantitating adherence of ruminal bacteria to cellulose.

    PubMed Central

    Rasmussen, M A; White, B A; Hespell, R B

    1989-01-01

    A quantitative technique suitable for the determination of adherence of ruminal bacteria to cellulose was developed. This technique employs adherence of cells to cellulose disks and alleviates the problem of nonspecific cell entrapment within cellulose particles. By using this technique, it was demonstrated that the adherence of Ruminococcus flavefaciens FD1 to cellulose was inhibited by formaldehyde, methylcellulose, and carboxymethyl cellulose. Adherence was unaffected by acid hydrolysates of methylcellulose, glucose, and cellobiose. PMID:2782879

  18. Understanding how adherence goals promote adherence behaviours: a repeated measure observational study with HIV seropositive patients

    PubMed Central

    2012-01-01

    Background The extent to which patients follow treatments as prescribed is pivotal to treatment success. An exceptionally high level (> 95%) of HIV medication adherence is required to suppress viral replication and protect the immune system and a similarly high level (> 80%) of adherence has also been suggested in order to benefit from prescribed exercise programmes. However, in clinical practice, adherence to both often falls below the desirable level. This project aims to investigate a wide range of psychological and personality factors that may lead to adherence/non-adherence to medical treatment and exercise programmes. Methods HIV positive patients who are referred to the physiotherapist-led 10-week exercise programme as part of the standard care are continuously recruited. Data on social cognitive variables (attitude, intention, subjective norms, self-efficacy, and outcome beliefs) about the goal and specific behaviours, selected personality factors, perceived quality of life, physical activity, self-reported adherence and physical assessment are collected at baseline, at the end of the exercise programme and again 3 months later. The project incorporates objective measures of both exercise (attendance log and improvement in physical measures such as improved fitness level, weight loss, improved circumferential anthropometric measures) and medication adherence (verified by non-invasive hair analysis). Discussion The novelty of this project comes from two key aspects, complemented with objective information on exercise and medication adherence. The project assesses beliefs about both the underlying goal such as following prescribed treatment; and about the specific behaviours such as undertaking the exercise or taking the medication, using both implicit and explicit assessments of patients’ beliefs and attitudes. We predict that i) the way people think about the underlying goal of their treatments explains medication and exercise behaviours over and above

  19. Medication Adherence in Psychopharmacologically Treated Adults with ADHD

    ERIC Educational Resources Information Center

    Safren, Steven A.; Duran, Petra; Yovel, Iftah; Perlman, Carol A.; Sprich, Susan

    2007-01-01

    Objective: One of the potential causes of residual symptoms of ADHD in adults can be difficulties with consistent adherence to medications. Method: This formative study examined self-reported medication adherence in adults with ADHD with clinically significant symptoms despite medication treatment. Results: Mean adherence for the two-week period…

  20. A Matter of Trust: Patient Barriers to Primary Medication Adherence

    ERIC Educational Resources Information Center

    Polinski, J. M.; Kesselheim, A. S.; Frolkis, J. P.; Wescott, P.; Allen-Coleman, C.; Fischer, M. A.

    2014-01-01

    Primary medication adherence occurs when a patient properly fills the first prescription for a new medication. Primary adherence only occurs about three-quarters of the time for antihypertensive medications. We assessed patients' barriers to primary adherence and attributes of patient-provider discussions that might improve primary adherence…

  1. Synthesis and Characterization of an Alumina Forming Nanolaminated Boride: MoAlB

    PubMed Central

    Kota, Sankalp; Zapata-Solvas, Eugenio; Ly, Alexander; Lu, Jun; Elkassabany, Omar; Huon, Amanda; Lee, William E.; Hultman, Lars; May, Steve J.; Barsoum, Michel W.

    2016-01-01

    The ‘MAlB’ phases are nanolaminated, ternary transition metal borides that consist of a transition metal boride sublattice interleaved by monolayers or bilayers of pure aluminum. However, their synthesis and properties remain largely unexplored. Herein, we synthesized dense, predominantly single-phase samples of one such compound, MoAlB, using a reactive hot pressing method. High-resolution scanning transmission electron microscopy confirmed the presence of two Al layers in between a Mo-B sublattice. Unique among the transition metal borides, MoAlB forms a dense, mostly amorphous, alumina scale when heated in air. Like other alumina formers, the oxidation kinetics follow a cubic time-dependence. At room temperature, its resistivity is low (0.36–0.49 μΩm) and – like a metal – drops linearly with decreasing temperatures. It is also a good thermal conductor (35 Wm−1K−1 at 26 °C). In the 25–1300 °C temperature range, its thermal expansion coefficient is 9.5 × 10−6 K−1. Preliminary results suggest the compound is stable to at least 1400 °C in inert atmospheres. Moderately low Vickers hardness values of 10.6 ± 0.3 GPa, compared to other transition metal borides, and ultimate compressive strengths up to 1940 ± 103 MPa were measured at room temperature. These results are encouraging and warrant further study of this compound for potential use at high temperatures. PMID:27220751

  2. Experimental and Theoretical Studies on the Viscosity-Structure Correlation for High Alumina-Silicate Melts

    NASA Astrophysics Data System (ADS)

    Talapaneni, Trinath; Yedla, Natraj; Pal, Snehanshu; Sarkar, Smarajit

    2017-03-01

    Blast furnaces are encountering high Alumina (Al2O3 > 25 pct) in the final slag due to the charging of low-grade ores. To study the viscosity behavior of such high alumina slags, synthetic slags are prepared in the laboratory scale by maintaining a chemical composition of Al2O3 (25 to 30 wt pct) CaO/SiO2 ratio (0.8 to 1.6) and MgO (8 to 16 wt pct). A chemical thermodynamic software FactSage 7.0 is used to predict liquidus temperature and viscosity of the above slags. Experimental viscosity measurements are performed above the liquidus temperature in the range of 1748 K to 1848 K (1475 °C to 1575 °C). The viscosity values obtained from FactSage closely fit with the experimental values. The viscosity and the slag structure properties are intent by Fourier Transform Infrared (FTIR) and Raman spectroscopy. It is observed that increase in CaO/SiO2 ratio and MgO content in the slag depolymerizes the silicate structure. This leads to decrease in viscosity and activation energy (167 to 149 kJ/mol) of the slag. Also, an addition of Al2O3 content increases the viscosity of slag by polymerization of alumino-silicate structure and activation energy from 154 to 161 kJ/mol. It is witnessed that the activation energy values obtained from experiment closely fit with the Shankar model based on Arrhenius equation.

  3. Medication Adherence among Older Adults with Schizophrenia

    PubMed Central

    Leutwyler, Heather C.; Fox, Patrick J.; Wallhagen, Margaret

    2014-01-01

    Older adults with schizophrenia are a growing segment of the population yet their physical and mental health status is extremely poor. The paper presents findings from a qualitative study that explored the understanding older adults with schizophrenia have of their physical health status. The study was conducted among 28 older adults with schizophrenia from a variety of settings using semi-structured interviews and participant observation. Self-management of psychiatric and non-psychiatric medications and its affect on their health status was one of the central themes that emerged from the study. Different styles of medication adherence were identified and factors associated with each style are presented. The findings provide insights into the design of clinical interventions aimed at promoting medication adherence among older adults with schizophrenia. PMID:23327119

  4. An ingestible sensor for measuring medication adherence.

    PubMed

    Hafezi, Hooman; Robertson, Timothy L; Moon, Greg D; Au-Yeung, Kit-Yee; Zdeblick, Mark J; Savage, George M

    2015-01-01

    In this paper, we describe the design and performance of the first integrated-circuit microsensor developed for daily ingestion by patients. The ingestible sensor is a device that allows patients, families, and physicians to measure medication ingestion and adherence patterns in real time, relate pharmaceutical compliance to important physiologic metrics, and take appropriate action in response to a patient's adherence pattern and specific health metrics. The design and theory of operation of the device are presented, along with key in-vitro and in-vivo performance results. The chemical, toxicological, mechanical, and electrical safety tests performed to establish the device's safety profile are described in detail. Finally, aggregate results from multiple clinical trials involving 412 patients and 5656 days of system usage are presented to demonstrate the device's reliability and performance as part of an overall digital health feedback system.

  5. Adherence and non-adherence to treatments: focus on pharmacy practice in Nepal.

    PubMed

    Bastakoti, Suresh; Khanal, Saval; Dahal, Bibek; Pun, Nirmala Tilija

    2013-04-01

    Nepal is one of the developing countries having many limitations in providing the quality health services to its population. In many countries, improvement in patients' adherence to the pharmacotherapy had been one of major outcome of quality pharmaceutical services. Till date, very less thing has been done in this area in Nepal; so it seems mandatory to improve the patient adherence to the treatment plans. Adherence to the medical therapy can be explained by the extent of the behavioral coincidence to the medication and non-medication regimen by a patient whereas compliance and concordance are two different models of patient adherence to the therapy. Compliance model suggests that patients have been brought responsible for being unable to follow 'doctor's order and concordance tempts to measure the degree of agreement between patient and his or her clinician about the nature of illness and the best possible therapy for the welfare of the patient. Non-adherence to the therapy may lead to different problems as consequences of non-adherence in four different level- individual, institutional, societal and national levels. Although some programs like, "Direct Observation Treatment, Short-course (DOTS) for tuberculosis, implementation of antiretroviral treatment schedules for HIV patients and pediatric vaccination models," are the examples of attention towards the cases of noncompliance in Nepal. It has long been faced its limitations in the forms of either untrained manpower or lack of good documentation of patients' adherence to therapy or high illiteracy rate or unaffordibility of patients to their treatment or lack of pharmaceutical care services.

  6. Marital satisfaction and adherence to religion

    PubMed Central

    Jafari, F; Neisani Samani, L; Fatemi, N; Ta’avoni, S; Abolghasemi, J

    2015-01-01

    Background: One of the most important determinants of health and marital satisfaction, the family and religious adherence can be effective because religion includes guidelines for life and providing a system of beliefs and values make these features can affect family life. Approach: This descriptive research - an analysis performed to assess the level of satisfaction of 47 questionnaires marital satisfaction questionnaire whose validity and reliability were evaluated and a couple of them asked to assess adherence to religion. The study population included 382 couples in Tehran that a cluster of 22 districts of Tehran were the selected. To analyze the data, ANOVA, Chi-square, and Pearson correlation coefficient using the software SPSS (version 22) became all tests were performed at the 5% level. Results: The data showed that the average age is 34 for women and 38 years for men and the majority of couples are in appropriate level in religiosity (40.5 percent). The results showed a main direct relation among religiosity and marital satisfaction of men and women (p ≤ 0.001). The correlation among religiosity and marital satisfaction of women r = 0.271 and this factor in men r = 0.200 was obtained indicating a direct relationship was significant. Conclusion: couples who were both committed to religion, their marital satisfaction score was more than couples without adherence to religion, and thus promoting religious beliefs and commitment can increase their marital satisfaction in couples. PMID:28316734

  7. [Drug prescriptions: Adherence and understanding in Madagascar].

    PubMed

    Raharinjatovo, L; Ralandison, S

    2015-01-01

    Frequently ignored or neglected, poor adherence is an important cause of treatment failure and a major public health problem. We assessed the factors involved in adherence in a hospital in Madagascar. This long-term study evaluated two groups of variables: patients' level of understanding of their disease and drug prescriptions, and the information on the prescription written by the doctor. We interviewed 93 in-patients (mean age: 50 years) and found that 16% were illiterate. Overall, 27% did not know the name of their illness, 34% were unaware of the treatment objectives, and 14% did not understand the drug prescription. On 20% of the prescriptions, the patients' name was not included, and the daily dose information and schedule was omitted from 16%. A day after receiving the prescription, only 64% had purchased the medication and only 53% of all patients had taken any. A correlation was observed between illiteracy, knowledge of the disease/treatment goals, and non-purchase of drugs. The poor quality of information contained in the prescriptions and patients' poor understanding of what they were supposed to do are obvious. Using pre-completed health forms and text messages might improve adherence.

  8. Patterned Thermoresponsive Microgel Coatings for Noninvasive Processing of Adherent Cells.

    PubMed

    Uhlig, Katja; Wegener, Thomas; He, Jian; Zeiser, Michael; Bookhold, Johannes; Dewald, Inna; Godino, Neus; Jaeger, Magnus; Hellweg, Thomas; Fery, Andreas; Duschl, Claus

    2016-03-14

    Cultivation of adherently growing cells in artificial environments is of utmost importance in medicine and biotechnology to accomplish in vitro drug screening or to investigate disease mechanisms. Precise cell manipulation, like localized control over adhesion, is required to expand cells, to establish cell models for novel therapies and to perform noninvasive cell experiments. To this end, we developed a method of gentle, local lift-off of mammalian cells using polymer surfaces, which are reversibly and repeatedly switchable between a cell-attractive and a cell-repellent state. This property was introduced through micropatterned thermoresponsive polymer coatings formed from colloidal microgels. Patterning was obtained through automated nanodispensing or microcontact printing, making use of unspecific electrostatic interactions between microgels and substrates. This process is much more robust against ambient conditions than covalent coupling, thus lending itself to up-scaling. As an example, wound healing assays were accomplished at 37 °C with highly increased precision in microfluidic environments.

  9. Composition, Microstructure, and Water Vapor Effects on Internal/External Oxidation of Alumina-Forming Austenitic (AFA) Stainless Steels

    SciTech Connect

    Brady, Michael P; Yamamoto, Yukinori; Santella, Michael L; Walker, Larry R

    2009-01-01

    A family of creep-resistant austenitic stainless steels based on alumina (Al2O3) scale formation for superior high-temperature oxidation resistance was recently identified. Results of long-term cyclic oxidation studies (100 h cycles and total exposure duration for up to 7500 h) from 650-800 aC in air and/or air with 10% water vapor for a series of 2.5, 3, and 4 wt.% Al AFA compositions, with varying levels of Nb and Ni additions, are presented. Water vapor was observed to enhance subscale Al consumption in the AFA alloys relative to dry air exposure, presumably via enhanced alumina scale cracking and reformation. Water vapor also increased the tendency for internal oxidation. Increased levels of Nb additions were found to significantly improve oxidation resistance, as were reactive element additions of Hf and Y. Computational thermodynamic calculations of the austenitic matrix phase composition and the volume fraction of MC, B2-NiAl, and Fe2Nb base Laves phase precipitates were used to guide interpretation of oxidation behavior alloy composition trends in terms of two-phase oxidation theory, reservoir effect, and the third-element effect of Cr. The implications of these findings for the upper-temperature service limit for this new class of alloys and the potential for AFA alloy modification for increased service temperatures are discussed.

  10. Interaction of hydrogen chloride with alumina. [atmospheric effluent concentrations and interaction of solid rocket propellants used in space shuttle

    NASA Technical Reports Server (NTRS)

    Bailey, R. R.; Wightman, J. P.

    1978-01-01

    The influence of temperature, pressure, and outgas conditions on the absorption of hydrogen chloride and water vapor on both alpha and gamma alumina was studied. Characterization of the adsorbents was performed using X-ray powder diffraction, scanning electron microscopy (SEM), low temperature nitrogen adsorption desorption measurements, BET nitrogen surface area measurements and electron spectroscopy for chemical analysis (ESCA). Water vapor adsorption isotherms at 30, 40, and 50 C were measured on alpha and gamma alumina after outgassing at 80, 200, and 400 C. Both outgas temperature and adsorption temperature influenced the adsorption of water vapor on the aluminas. The water vapor adsorption was completely reversible. Alpha alumina absorbed more water per unit area than gamma alumina. Differences in the adsorption capacity for water vapor of the two aluminas were explained on the basis of ideal surface models of alpha and gamma alumina. Isosteric heats of adsorption for water vapor on the aluminas were determined over a limited range of surface coverage.

  11. Intermetallic strengthened alumina-forming austenitic steels for energy applications

    NASA Astrophysics Data System (ADS)

    Hu, Bin

    In order to achieve energy conversion efficiencies of >50 % for steam turbines/boilers in power generation systems, materials required are strong, corrosion-resistant at high temperatures (>700°C), and economically viable. Austenitic steels strengthened with Laves phase and Ni3Al precipitates, and alloyed with aluminum to improve oxidation resistance, are potential candidate materials for these applications. The creep resistance of these alloys is significantly improved through intermetallic strengthening (Laves-Fe 2Nb + L12-Ni3Al precipitates) without harmful effects on oxidation resistance. This research starts with microstructural and microchemical analyses of these intermetallic strengthened alumina-forming austenitic steels in a scanning electron microscope. The microchemistry of precipitates, as determined by energy-dispersive x-ray spectroscopy and transmission electron microscope, is also studied. Different thermo-mechanical treatments were carried out to these stainless steels in an attempt to further improve their mechanical properties. The microstructural and microchemical analyses were again performed after the thermo-mechanical processing. Synchrotron X-ray diffraction was used to measure the lattice parameters of these steels after different thermo-mechanical treatments. Tensile tests at both room and elevated temperatures were performed to study mechanical behaviors of this novel alloy system; the deformation mechanisms were studied by strain rate jump tests at elevated temperatures. Failure analysis and post-mortem TEM analysis were performed to study the creep failure mechanisms of these alumina-forming austenitic steels after creep tests. Experiments were carried out to study the effects of boron and carbon additions in the aged alumina-forming austenitic steels.

  12. Relationship of treatment satisfaction to medication adherence: findings from a cross-sectional survey among hypertensive patients in Palestine

    PubMed Central

    2013-01-01

    Background The concepts of medication adherence and Treatment satisfactions are commonly used in clinical research for assessing pharmaceutical care and improving treatment outcomes. Generally, one would expect a positive relationship between the two concepts. The objectives of this study were to investigate the factors associated with adherence to antihypertensive therapy among hypertensive patients and to assess the relationship between antihypertensive medication adherence and treatment satisfaction. Methods A cross-sectional study was conducted, adopting the Morisky eight-item Medication Adherence Scale (MMAS) for the assessment of medication adherence and using the Treatment Satisfaction Questionnaire for Medication (TSQM 1.4) for the assessment of treatment satisfaction. Descriptive and comparative statistics were used to describe socio-demographic and disease-related characteristics of the patients. All analyses were performed using SPSS v 15.0. Results Four hundred and ten hypertensive patients were enrolled in the study. The mean age of participants was 58.38 ± 10.65 years; 52% were female and 36.8% had low antihypertensive medication adherence. There was a significant difference in the mean scores in the Effectiveness (p < 0.001), Convenience (p < 0.001), and Global Satisfaction (p < 0.001) domains, but not in the Side Effects (p = 0.466) domain among patients with different levels of adherence. After adjustment for covariates using multiple linear regression, global treatment satisfaction was still statistically significantly (p = 0.001) associated with medication adherence. Conclusions Low treatment satisfaction may be an important barrier for achieving high rates of adherence to treatment. These study findings could be helpful in clinical practice, mainly in the early treatment of hypertensive patients, at a point where improving treatment satisfaction is still possible. PMID:24195638

  13. Adherence to Varenicline Among African American Smokers: An Exploratory Analysis Comparing Plasma Concentration, Pill Count, and Self-report

    PubMed Central

    Berg, Carla J.; Cox, Lisa Sanderson; Nazir, Niaman; Benowitz, Neal L.; Yu, Lisa; Yturralde, Olivia; Jacob, Peyton; Choi, Won S.; Ahluwalia, Jasjit S.; Nollen, Nicole L.

    2012-01-01

    Introduction: Measuring adherence to smoking cessation pharmacotherapy is important to evaluating its effectiveness. Blood levels are considered the most accurate measure of adherence but are invasive and costly. Pill counts and self-report are more practical, but little is known about their relationship to blood levels. This study compared the validity of pill count and self-report against plasma varenicline concentration for measuring pharmacotherapy adherence. Methods: Data were obtained from a randomized pilot study of varenicline for smoking cessation among African American smokers. Adherence was measured on Day 12 via plasma varenicline concentration, pill count, 3-day recall, and a visual analogue scale (VAS; adherence was represented on a line with two extremes “no pills” and “all pills”). Results: The sample consisted of 55 African American moderate to heavy smokers (average 16.8 cigarettes/day, SD = 5.6) and 63.6% were female. Significant correlations (p < .05) were found between plasma varenicline concentration and pill count (r = .56), 3-day recall (r = .46), and VAS (r = .29). Using plasma varenicline concentration of 2.0 ng/ml as the cutpoint for adherence, pill count demonstrated the largest area under the receiver operating characteristic curve (AUC = 0.85, p = .01) and had 88% sensitivity (95% CI = 75.0–95.0) and 80% specificity (95% CI = 30.0–99.0) for detecting adherence. Conclusions: Of 3 commonly used adherence measures, pill count was the most valid for identifying adherence in this sample of African American smokers. Pill count has been used across other health domains and could be incorporated into treatment to identify nonadherence, which, in turn, could maximize smoking cessation pharmacotherapy use and improve abstinence rates. PMID:22367976

  14. Validity and Reliability of a Self-Reported Measure of Antihypertensive Medication Adherence in Uganda

    PubMed Central

    Nasasira, Benson; Muiru, Anthony Ndichu Wa; Muyingo, Anthony

    2016-01-01

    Background The Morisky Medication Adherence scale (MMAS-8) is a widely used self-reported measure of adherence to antihypertensive medications that has not been validated in hypertensive patients in sub-Saharan Africa. Methods We carried out a cross-sectional study to examine psychometric properties of a translated MMAS-8 (MMAS-U) in a tertiary care hypertension clinic in Uganda. We administered the MMAS-U to consecutively selected hypertensive adults and used principal factor analysis and Cronbach’s alpha to determine its validity and internal consistency respectively. Then we randomly selected one-sixth of participants for a 2-week test-retest telephone interview. Lastly, we used ordinal logistic regression modeling to explore factors associated with levels of medication adherence. Results Of the 329 participants, 228 (69%) were females, median age of 55 years [Interquartile range (IQR) (46–66)], and median duration of hypertension of 4 years [IQR (2–8)]. The adherence levels were low (MMAS-U score ≤ 5) in 85%, moderate (MMAS-U score 6–7) in 12% and high (MMAS-U score ≥8) in 3%. The factor analysis of construct validity was good (overall Kaiser’s measure of sampling adequacy for residuals of 0.72) and identified unidimensionality of MMAS-U. The internal consistency of MMAS-U was moderate (Cronbach α = 0.65), and test-retest reliability was low (weighted kappa = 0.36; 95% CI -0.01, 0.73). Age of 40 years or greater was associated with low medication adherence (p = 0.02) whereas a family member buying medication for participants (p = 0.02) and purchasing medication from a private clinic (p = 0.02) were associated with high adherence. Conclusion The Ugandan version of the MMAS-8 (MMAS-U) is a valid and reliable measure of adherence to antihypertensive medication among Ugandan outpatients receiving care at a public tertiary facility. Though the limited supply of medication affected adherence, this easy to use tool can be adapted to assess medication

  15. Systematic Review of Educational Interventions to Improve Glaucoma Medication Adherence

    PubMed Central

    Newman-Casey, Paula Anne; Weizer, Jennifer S.; Heisler, Michele; Lee, Paul P.; Stein, Joshua D.

    2014-01-01

    Adherence to prescribed glaucoma medications is often poor, and proper adherence can be challenging for patients. We systematically reviewed the literature and identified eight studies using educational interventions to improve glaucoma medication adherence. Overall, five of the eight studies found that educational interventions lead to a significant improvement in medication adherence, and the remaining studies found a trend towards improvement. Using information from this systematic review and Health Behavior Theory, we constructed a conceptual framework to illustrate how counseling and education can improve glaucoma medication adherence. More rigorous studies grounded in Health Behavior Theory with adequately powered samples and longer follow-up are needed. PMID:23697623

  16. Functionally graded alumina-based thin film systems

    DOEpatents

    Moore, John J.; Zhong, Dalong

    2006-08-29

    The present invention provides coating systems that minimize thermal and residual stresses to create a fatigue- and soldering-resistant coating for aluminum die casting dies. The coating systems include at least three layers. The outer layer is an alumina- or boro-carbide-based outer layer that has superior non-wettability characteristics with molten aluminum coupled with oxidation and wear resistance. A functionally-graded intermediate layer or "interlayer" enhances the erosive wear, toughness, and corrosion resistance of the die. A thin adhesion layer of reactive metal is used between the die substrate and the interlayer to increase adhesion of the coating system to the die surface.

  17. Preparation Of Strong, Dense Potassium Beta''-Alumina Ceramic

    NASA Technical Reports Server (NTRS)

    Williams, Roger M.; Jeffries-Nakamura, Barbara; Ryan, Margaret A.; O'Connor, Dennis E.; Kisor, Adam; Kikkert, Stanley J.; Losey, Robert; Suitor, Jerry W.

    1995-01-01

    Improved process for making mechanically strong, dense, phase-pure potassium beta''-alumina solid electrolyte (K-BASE) results in material superior to all previous K-BASE preparations and similar to commercial Na-BASE in strength, phase purity and high-temperature ionic conductivity. Potassium-based alkali-metal thermal-to-electric conversion (AMTEC) cells expected to operate efficiently at lower heat-input temperatures and lower rejection temperatures than sodium-based AMTEC cells, making them appropriate for somewhat different applications.

  18. Fractal dimension of alumina aggregates grown in two dimensions

    NASA Technical Reports Server (NTRS)

    Larosa, Judith L.; Cawley, James D.

    1992-01-01

    The concepts of fractal geometry are applied to the analysis of 0.4-micron alumina constrained to agglomerate in two dimensions. Particles were trapped at the bottom surface of a drop of a dilute suspension, and the agglomeration process was directly observed, using an inverted optical microscope. Photographs were digitized and analyzed, using three distinct approaches. The results indicate that the agglomerates are fractal, having a dimension of approximately 1.5, which agrees well with the predictions of the diffusion-limited cluster-cluster aggregation model.

  19. Method for thermal processing alumina-enriched spinel single crystals

    DOEpatents

    Jantzen, Carol M.

    1995-01-01

    A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly.

  20. Method for thermal processing alumina-enriched spinel single crystals

    DOEpatents

    Jantzen, C.M.

    1995-05-09

    A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly. 12 figs.