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Sample records for air contrast barium

  1. Aspiration of Barium Contrast

    PubMed Central

    Fuentes Santos, Cristina; Steen, Bárbara

    2014-01-01

    The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient's medical file was reviewed, images were found of a barium swallow study that the patient had undergone months earlier, and we were able to observe the exact moment of the aspiration of the contrast material. The patient had been asymptomatic since the test. PMID:25309769

  2. Changes in the Small Intestine of a Cat Associated with Barium Sulphate Following Contrast Radiography.

    PubMed

    Igarashi, H; Oishi, M; Ohno, K; Tsuboi, M; Irie, N; Uchida, K; Tsujimoto, H

    2016-01-01

    A 7-year-old neutered male domestic short-haired cat that had undergone contrast radiography of the bowel with barium sulphate after acute episodes of vomiting 2 months previously, was presented with chronic vomiting, anorexia and weight loss. Abdominal radiography and ultrasonography revealed residual contrast enhancement and an obstruction of the small intestine. A contracted and stenosed ileum and distal jejunum were identified by exploratory laparotomy and surgically resected; subsequently, the clinical signs resolved. Histopathological examination of the ileum revealed mucosal ulceration with severe submucosal granulation tissue formation associated with scattered foreign crystalline material. Energy-dispersive X-ray spectroscopy revealed that the crystals contained barium sulphate. This is the first report in animals of the rare complication of barium sulphate incorporation into the gastrointestinal mucosa after contrast radiography. PMID:26997652

  3. Effect of glucagon on the diagnostic accuracy of double-contrast barium enema examinations.

    PubMed

    Thoeni, R F; Vandeman, F; Wall, S D

    1984-01-01

    The effect of glucagon-induced hypotonicity on the diagnostic accuracy of double-contrast barium enema examinations was determined in 133 consecutive patients in a double-blind crossover study. All patients underwent colonoscopy and served as their own controls by undergoing a double-contrast study after intravenous injection of 1 mg of glucagon and another after intravenous injection of 1 ml of saline placebo, in randomized order. The frequencies of good/excellent hypotonicity and quality of examinations after first doses of glucagon (55.3% and 80.8%) were not significantly different from the frequencies of good/excellent results after first doses of saline (51.3% and 86.5%). The sensitivity was 72.6% after glucagon and 64.5% after placebo; the specificity was 88.7% after glucagon and 77.9% after placebo; and the respective accuracies were 81.2% and 71.9%. These percentages should be used only to compare results with and without glucagon and, by study design, do not represent results of a complete double-contrast study. The variation among these percentages was not statistically significant, but diverticulitis was more accurately diagnosed after glucagon. It was concluded that glucagon does not significantly improve the sensitivity and specificity of the double-contrast barium enema examination and should be used only in selected instances. PMID:6606942

  4. Comparison of Golytely lavage with standard diet/cathartic preparation for double-contrast barium enema.

    PubMed

    Girard, C M; Rugh, K S; DiPalma, J A; Brady, C E; Pierson, W P

    1984-06-01

    In a two-part study, two groups of 100 outpatients each were randomly assigned a colon preparation. In part 1, a standard 1-day diet/cathartic combination was compared with Golytely. In part 2, diet/cathartics was compared with Golytely plus Dulcolax (bisacodyl). The standard preparation provided good or excellent feces removal in 81 (80%) of 101 subjects. Golytely alone was successful in only 21 (53%) of 40 patients, but Golytely followed by Dulcolax achieved good or excellent feces removal in 31 (82%) of 38. Degraded mucosal coating with Golytely alone, due to excessive fluid retention, was also corrected by the addition of Dulcolax. Golytely alone is not an adequate method of colon cleansing for double-contrast barium enema, but Golytely plus Dulcolax is as effective as the standard preparation. PMID:6609598

  5. [Primary double contrast study of the large intestine using citrate-sorbitol-barium suspension in the diagnosis of chronic colitis].

    PubMed

    Sidorov, V S

    1991-01-01

    X-ray investigation of the colon was conducted in 292 patients with clinically diagnosed chronic colitis: standard 3-phase irrigoscopy-in 189 patients and a primary double contrast study of the colon with citrate-sorbitol-barium suspension in 103. Basing on x-ray and morphological findings, the diagnosis was confirmed in 128 patients of the 1st group (68.2%) and in 89 patients of the 2nd group (86%). The primary double contrast study of the colon was found more effective as it permitted the detection of elements of the mucosal "microcontours": transversal strips, not coinciding with haustration, focal granularity, diffuse granularity, small barium suspension "depots" or "niches", nodular granularity. It permitted the recommendation of the method for a wide clinical use. PMID:1996079

  6. Micro-Computed Tomography of Fatigue Microdamage in Cortical Bone Using a Barium Sulfate Contrast Agent

    PubMed Central

    Leng, Huijie; Wang, Xiang; Ross, Ryan D.; Niebur, Glen L.; Roeder, Ryan K.

    2008-01-01

    Accumulation of microdamage during fatigue can lead to increased fracture susceptibility in bone. Current techniques for imaging microdamage in bone are inherently destructive and two-dimensional. Therefore, the objective of this study was to image the accumulation of fatigue microdamage in cortical bone using micro-computed tomography (micro-CT) with a barium sulfate (BaSO4) contrast agent. Two symmetric notches were machined on the tensile surface of bovine cortical bone beams in order to generate damage ahead of the stress concentrations during four-point bending fatigue. Specimens were loaded to a specified number of cycles or until one notch fractured, such that the other notch exhibited the accumulation of microdamage prior to fracture. Microdamage ahead of the notch was stained in vitro by precipitation of BaSO4 and imaged using micro-CT. Reconstructed images showed a distinct region of bright voxels around the notch tip or along propagating cracks due to the presence of BaSO4, which was verified by backscattered electron imaging and energy dispersive spectroscopy. The shape of the stained region ahead of the notch tip was consistent with principal strain contours calculated by finite element analysis. The relative volume of the stained region was correlated with the number of loading cycles by non-linear regression using a power-law. This study demonstrates new methods for the non-destructive and three-dimensional detection of fatigue microdamage accumulation in cortical bone in vitro, which may be useful to gain further understanding into the role of microdamage in bone fragility. PMID:18443659

  7. Barium enema (image)

    MedlinePlus

    A barium enema is performed to examine the walls of the colon. During the procedure, a well lubricated enema tube is inserted gently into the rectum. The barium, a radiopaque (shows up on X-ray) contrast ...

  8. Radiographic anatomy and barium sulfate contrast transit time of the gastrointestinal tract of bearded dragons (Pogona vitticeps).

    PubMed

    Grosset, Claire; Daniaux, Lise; Guzman, David Sanchez-Migallon; Weber, Ernest Scott; Zwingenberger, Allison; Paul-Murphy, Joanne

    2014-01-01

    The positive contrast gastrointestinal study is a common non-invasive diagnostic technique that does not require anesthesia and enables good visualization of the digestive tract. Radiographic anatomy and reference intervals for gastrointestinal contrast transit time in inland bearded dragons (Pogona vitticeps) were established using seven animals administered 15 ml/kg of a 35% w/v suspension of barium by esophageal gavage. Dorso-ventral and lateral radiographic views were performed at 0, 15, 30 min, 1, 2, 4, 6, 8, 12 h, and then every 12 h up to 96 h after barium administration. Gastric emptying was complete at a median time of 10 h (range 4-24 h). Median jejunum and small intestinal emptying times were 1 h (range 30 min-2 h) and 29 h (range 24-48 h), respectively. Median transit time for cecum was 10 h (range 8-12 h). Median time for contrast to reach the colon was 31 h (range 12-72 h) after administration. Results were compared to those obtained in other reptilian species. This technique appeared safe in fasted bearded dragons and would be clinically applicable in other lizard species. PMID:24945023

  9. Functionalized synchrotron in-line phase-contrast computed tomography: a novel approach for simultaneous quantification of structural alterations and localization of barium-labelled alveolar macrophages within mouse lung samples.

    PubMed

    Dullin, Christian; dal Monego, Simeone; Larsson, Emanuel; Mohammadi, Sara; Krenkel, Martin; Garrovo, Chiara; Biffi, Stefania; Lorenzon, Andrea; Markus, Andrea; Napp, Joanna; Salditt, Tim; Accardo, Agostino; Alves, Frauke; Tromba, Giuliana

    2015-01-01

    Functionalized computed tomography (CT) in combination with labelled cells is virtually non-existent due to the limited sensitivity of X-ray-absorption-based imaging, but would be highly desirable to realise cell tracking studies in entire organisms. In this study we applied in-line free propagation X-ray phase-contrast CT (XPCT) in an allergic asthma mouse model to assess structural changes as well as the biodistribution of barium-labelled macrophages in lung tissue. Alveolar macrophages that were barium-sulfate-loaded and fluorescent-labelled were instilled intratracheally into asthmatic and control mice. Mice were sacrificed after 24 h, lungs were kept in situ, inflated with air and scanned utilizing XPCT at the SYRMEP beamline (Elettra Synchrotron Light Source, Italy). Single-distance phase retrieval was used to generate data sets with ten times greater contrast-to-noise ratio than absorption-based CT (in our setup), thus allowing to depict and quantify structural hallmarks of asthmatic lungs such as reduced air volume, obstruction of airways and increased soft-tissue content. Furthermore, we found a higher concentration as well as a specific accumulation of the barium-labelled macrophages in asthmatic lung tissue. It is believe that XPCT will be beneficial in preclinical asthma research for both the assessment of therapeutic response as well as the analysis of the role of the recruitment of macrophages to inflammatory sites. PMID:25537601

  10. Flexible fiberoptic sigmoidoscopy and double-contrast barium-enema examination in the identification of adenomas and carcinoma of the colon.

    PubMed

    Farrands, P A; Vellacott, K D; Amar, S S; Balfour, T W; Hardcastle, J D

    1983-11-01

    To assess the accuracy of the flexible fiberoptic sigmoidoscope, 227 consecutive patients (mean age 61.8 +/- 13 years) requiring investigation of colonic symptoms were evaluated using rigid and flexible sigmoidoscopy (PAF and KDV) and double-contrast barium enema (SSA). Patients with equivocal findings or adenomatous polyps underwent colonoscopy (TWB). Thirty-four patients had carcinoma and 50 patients had one or more adenomatous polyps (greater than 5mm). The neoplastic yield from rigid sigmoidoscopy was 12 per cent, flexible fiberoptic sigmoidoscopy 90 per cent, and double-contrast barium enema only 76 per cent. Barium enema failed to identify eight carcinomas and 13 adenomatous polyps; seven of the eight carcinomas were polypoid Dukes' Stage A lesions, and associated diverticular disease was present in 62.5 per cent of cases. Flexible fiberoptic sigmoidoscopy failed to identify seven carcinomas and one adenomatous polyp. Five of the carcinomas were beyond range of the instrument; in one patient, a stricture was seen that was caused by the carcinoma; and in the seventh patient, the examination was terminated because of angulation spasm. Double-contrast barium enema is inaccurate in detecting lesions in the sigmoid colon, with flexible sigmoidoscopy being superior. PMID:6628146

  11. Barium enema

    MedlinePlus

    ... series; Colorectal cancer - lower GI series; Colorectal cancer - barium enema; Crohn disease - lower GI series; Crohn disease - barium enema; Intestinal blockage - lower GI series; Intestinal blockage - ...

  12. Barium Sulfate

    MedlinePlus

    Barium sulfate is used to help doctors examine the esophagus (tube that connects the mouth and stomach), ... dimensional pictures of the inside of the body). Barium sulfate is in a class of medications called ...

  13. The contrast model method for the thermodynamical calculation of air-air wet heat exchanger

    NASA Astrophysics Data System (ADS)

    Yuan, Xiugan; Mei, Fang

    1989-02-01

    The 'contrast model' method thermodynamic calculation of air-air crossflow wet heat exchangers with initial air condensation is presented. Contrast-model equations are derived from the actual heat exchanger equations as well as imaginary ones; it is then possible to proceed to a proof that the enthalpy efficiency of the contrast model equations is similar to the temperature efficiency of the dry heat exchanger. Conditions are noted under which it becomes possible to unify thermodynamic calculations for wet and dry heat exchangers.

  14. Observed Barium Emission Rates

    NASA Technical Reports Server (NTRS)

    Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.

    1993-01-01

    The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.

  15. The value of colonoscopy and double-contrast barium-enema examinations in the evaluation of patients with subacute and chronic lower intestinal bleeding

    SciTech Connect

    Thoeni, R.F.; Venbrux, A.C.

    1983-03-01

    One hundred thirty six consecutive patients were examined with histories of guaiac positive stool examinations, bright red blood per rectum, or hematochezia to determine the value of the double-contrast barium-enema (DC-BE) examination and colonoscopy/proctoscopy in establishing bleeding sites. If examination findings were analyzed in conjunction with findings of visual examination of the anal area, the difference in the respective sensitivities of the two examinations was not statistically significant. If findings at the visual inspection were excluded, the DC-BE examination missed 45 of 155 proved bleeding sites (sensitivity, 71%) and 13 of 35 nonbleeding lesions (sensitivity for all lesions 70%), while colonoscopy missed 13 of 155 bleeding sites (sensitivity, 92%) and seven of 35 nonbleeding lesions (sensitivity for all lesions, 90%). The sensitivity of both methods was similar if all rectal and anal lesions were excluded. We conclude that colonoscopy is superior to the DC-BE examination in the detection of bleeding sites but similar in results to the DC-BE examination if lesions in the anal canal and rectum are excluded. The routine use of the DC-BE examination in patients with superficial lesions in the anal canal should be discouraged unless the patient has persistent bleeding or is 50 years old or older.

  16. Barium cyanide

    Integrated Risk Information System (IRIS)

    Barium cyanide ; CASRN 542 - 62 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  17. Improving AIRS radiance spectra in high contrast scenes using MODIS

    NASA Astrophysics Data System (ADS)

    Pagano, Thomas S.; Aumann, Hartmut H.; Manning, Evan M.; Elliott, Denis A.; Broberg, Steven E.

    2015-09-01

    The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua Spacecraft was launched on May 4, 2002. AIRS acquires hyperspectral infrared radiances in 2378 channels ranging in wavelength from 3.7-15.4 um with spectral resolution of better than 1200, and spatial resolution of 13.5 km with global daily coverage. The AIRS is designed to measure temperature and water vapor profiles for improvement in weather forecast accuracy and improved understanding of climate processes. As with most instruments, the AIRS Point Spread Functions (PSFs) are not the same for all detectors. When viewing a non-uniform scene, this causes a significant radiometric error in some channels that is scene dependent and cannot be removed without knowledge of the underlying scene. The magnitude of the error depends on the combination of non-uniformity of the AIRS spatial response for a given channel and the non-uniformity of the scene, but is typically only noticeable in about 1% of the scenes and about 10% of the channels. The current solution is to avoid those channels when performing geophysical retrievals. In this effort we use data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument to provide information on the scene uniformity that is used to correct the AIRS data. For the vast majority of channels and footprints the technique works extremely well when compared to a Principal Component (PC) reconstruction of the AIRS channels. In some cases where the scene has high inhomogeneity in an irregular pattern, and in some channels, the method can actually degrade the spectrum. Most of the degraded channels appear to be slightly affected by random noise introduced in the process, but those with larger degradation may be affected by alignment errors in the AIRS relative to MODIS or uncertainties in the PSF. Despite these errors, the methodology shows the ability to correct AIRS radiances in non-uniform scenes under some of the worst case conditions and improves the ability to match

  18. BARIUM RECOVERY PROCESS

    DOEpatents

    Blanco, R.E.

    1959-07-21

    A method of separating barium from nuclear fission products is described. In accordance with the invention, barium may be recovered from an acidic solution of neutron-irradiated fissionable material by carrying ihe barium cut of solution as a sulfate with lead as a carrier and then dissolving the barium-containing precipitate in an aqueous solution of an aliphatic diamine chelating reagent. The barium values together with certain other metallic values present in the diamine solution are then absorbed onto a cation exchange resin and the barium is selectively eluted from the resin bed with concentrated nitric acid.

  19. Dynamic measures of regional lung air volume using phase contrast x-ray imaging

    NASA Astrophysics Data System (ADS)

    Kitchen, M. J.; Lewis, R. A.; Morgan, M. J.; Wallace, M. J.; Siew, M. L.; Siu, K. K. W.; Habib, A.; Fouras, A.; Yagi, N.; Uesugi, K.; Hooper, S. B.

    2008-11-01

    Phase contrast x-ray imaging can provide detailed images of lung morphology with sufficient spatial resolution to observe the terminal airways (alveoli). We demonstrate that quantitative functional and anatomical imaging of lung ventilation can be achieved in vivo using two-dimensional phase contrast x-ray images with high contrast and spatial resolution (<100 µm) in near real time. Changes in lung air volume as small as 25 µL were calculated from the images of term and preterm rabbit pup lungs (n = 28) using a single-image phase retrieval algorithm. Comparisons with plethysmography and computed tomography showed that the technique provided an accurate and robust method of measuring total lung air volumes. Furthermore, regional ventilation was measured by partitioning the phase contrast images, which revealed differences in aeration for different ventilation strategies.

  20. Suicidal ingestion of barium-sulfide-containing shaving powder.

    PubMed

    Downs, J C; Milling, D; Nichols, C A

    1995-03-01

    Physicians, familiar with the common usage of barium medicinally as the contrast agent barium sulfate, may consider it an innocuous or at most a minimally harmful compound. The barium cation is extremely toxic and produces characteristic gastrointestinal symptoms, periorbital and extremity paresthesia, hypertension, and progressive flaccid muscular paralysis. Profound hypokalemia also may be induced. Overdose may be rapidly fatal unless the ingestion is recognized and appropriate treatment is instituted expediently. PMID:7771386

  1. Stable Encapsulation of Air in Mesoporous Silica Nanoparticles: Fluorocarbon-Free Nanoscale Ultrasound Contrast Agents.

    PubMed

    Yildirim, Adem; Chattaraj, Rajarshi; Blum, Nicholas T; Goldscheitter, Galen M; Goodwin, Andrew P

    2016-06-01

    While gas-filled micrometer-sized ultrasound contrast agents vastly improve signal-to-noise ratios, microbubbles have short circulation lifetimes and poor extravasation from the blood. Previously reported fluorocarbon-based nanoscale contrast agents are more stable but their contrast is generally lower owing to their size and dispersity. The contrast agents reported here are composed of silica nanoparticles of ≈100 nm diameter that are filled with ≈3 nm columnar mesopores. Functionalization of the silica surface with octyl groups and resuspension with Pluronic F127 create particles with pores that remain filled with air but are stable in buffer and serum. Administration of high intensity focused ultrasound (HIFU) allows sensitive imaging of the silica nanoparticles down to 10(10) particles mL(-1) , with continuous imaging for at least 20 min. Control experiments with different silica particles supported the hypothesis that entrapped air could be pulled into bubble nuclei, which can then in turn act as acoustic scatterers. This process results in very little hemolysis in whole blood, indicating potential for nontoxic blood pool imaging. Finally, the particles are lyophilized and reconstituted or stored in PBS (phosphate-buffered saline, at least for four months) with no loss in contrast, indicating stability to storage and reformulation. PMID:26990167

  2. Barium release system

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.; Stokes, C. S.; Smith, E. W.; Murphy, W. J. (Inventor)

    1973-01-01

    A chemical system is described for releasing a good yield of free barium neutral atoms and barium ions in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium. The barium is released in the vapor phase so that it can be ionized by solar radiation and also be excited to emit resonance radiation in the visible range. The ionized luminous cloud of barium becomes a visible indication of magnetic and electrical characteristics in space and allows determination of these properties over relatively large areas at a given time.

  3. Pesticide detection in air samples from contrasted houses and in their inhabitants' hair.

    PubMed

    Raeppel, Caroline; Salquèbre, Guillaume; Millet, Maurice; Appenzeller, Brice M R

    2016-02-15

    In order to identify associations between indoor air contamination and human exposure to pesticides, hair samples from 14 persons (9 adults and 5 children below 12 years) were collected simultaneously with the air of their 5 contrasted houses. Three houses were situated in Alsace (France), one in Lorraine (France) and one in Luxembourg (Luxembourg). Houses were located in urban (n=3), semi-urban (n=1) and rural areas (n=1). Twenty five (25) pesticides were detected at least once in indoor air samples and 20 pesticides were detected at least once in hair samples. The comparison between hair and air samples for the same sampling periods shows that pesticides detected in the two matrices were not necessarily associated. Exposure profiles varied from one home to another but also between inhabitants of the same home, suggesting that exposure can be different between inhabitants of the same home. This study demonstrated the usefulness and the complementarity of hair analysis, for the personalized biomonitoring of people exposure to pesticides, and air analysis, for the identification of airborne exposure and house contamination. PMID:26706757

  4. Suspended Si/air high contrast subwavelength gratings for long-wavelength infrared reflectors

    NASA Astrophysics Data System (ADS)

    Foley, Justin M.; Phillips, Jamie D.

    2013-03-01

    We report broadband reflectance in the long-wavelength infrared (LWIR, 8-12 μm) utilizing suspended-Si, high-index-contrast subwavelength gratings (HCGs). Iterative design optimization using finite element analysis software has been performed accounting for silicon's wavelength-dependent index of refraction and extinction coefficient. Grating arrays were fabricated using commercial silicon-on-insulator (SOI) substrates, photolithography and reactive ion etching; subsequent selective wet etching of SiO2 was used to provide suspended Si/air gratings. Fourier transform infrared (FTIR) spectroscopy demonstrates broadband, polarization-dependent reflectance between 8.5 and 12 μm, which agrees with the simulated response.

  5. Solar eclipse sign of intussusception on barium enema.

    PubMed

    Raveenthiran, V

    2002-01-01

    The colographic appearance of intussusception is variously described as a claw sign, pincer defect, shouldering effect, and coiled-spring pattern. This report adds a new radiographic sign to the list. An end-on view of an intussusception on barium enema shows a ring of contrast resembling a solar eclipse. Familiarity with this bizarre appearance is desirable, lest it may be mistaken for spillage of barium due to a colonic perforation. PMID:11793074

  6. Barium and Compounds

    Integrated Risk Information System (IRIS)

    Barium and Compounds ; CASRN 7440 - 39 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  7. Microstructured Air Cavities as High-Index Contrast Substrates with Strong Diffraction for Light-Emitting Diodes.

    PubMed

    Moon, Yoon-Jong; Moon, Daeyoung; Jang, Jeonghwan; Na, Jin-Young; Song, Jung-Hwan; Seo, Min-Kyo; Kim, Sunghee; Bae, Dukkyu; Park, Eun Hyun; Park, Yongjo; Kim, Sun-Kyung; Yoon, Euijoon

    2016-05-11

    Two-dimensional high-index-contrast dielectric gratings exhibit unconventional transmission and reflection due to their morphologies. For light-emitting devices, these characteristics help guided modes defeat total internal reflections, thereby enhancing the outcoupling efficiency into an ambient medium. However, the outcoupling ability is typically impeded by the limited index contrast given by pattern media. Here, we report strong-diffraction, high-index-contrast cavity engineered substrates (CESs) in which hexagonally arranged hemispherical air cavities are covered with a 80 nm thick crystallized alumina shell. Wavelength-resolved diffraction measurements and Fourier analysis on GaN-grown CESs reveal that the high-index-contrast air/alumina core/shell patterns lead to dramatic excitation of the low-order diffraction modes. Large-area (1075 × 750 μm(2)) blue-emitting InGaN/GaN light-emitting diodes (LEDs) fabricated on a 3 μm pitch CES exhibit ∼39% enhancement in the optical power compared to state-of-the-art, patterned-sapphire-substrate LEDs, while preserving all of the electrical metrics that are relevant to LED devices. Full-vectorial simulations quantitatively demonstrate the enhanced optical power of CES LEDs and show a progressive increase in the extraction efficiency as the air cavity volume is expanded. This trend in light extraction is observed for both lateral- and flip-chip-geometry LEDs. Measurements of far-field profiles indicate a substantial beaming effect for CES LEDs, despite their few-micron-pitch pattern. Near-to-far-field transformation simulations and polarization analysis demonstrate that the improved extraction efficiency of CES LEDs is ascribed to the increase in emissions via the top escape route and to the extraction of transverse-magnetic polarized light. PMID:27045458

  8. FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

    NASA Astrophysics Data System (ADS)

    Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

    2010-01-01

    Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

  9. Barium Peritonitis in Small Animals

    PubMed Central

    KO, Jae Jin; MANN, F. A. (Tony)

    2014-01-01

    ABSTRACT Barium peritonitis is extremely rare, but is difficult to treat and may be life-threatening. Barium suspension leakage from the gastrointestinal tract into the abdominal cavity has a time-dependent and synergistically deleterious effect in patients who have generalized bacterial peritonitis. The severity of barium peritonitis is dependent on the quantity of barium in the abdominal cavity. Barium sulfate leakage results in hypovolemia and hypoproteinemia by worsening the exudation of extracellular fluid and albumin. Abdominal fluid analysis is a useful and efficient method to diagnose barium peritonitis. Serial radiographs may not be a reliable or timely diagnostic technique. Initial aggressive fluid resuscitation and empirical broad-spectrum antibiotic treatment should be instituted promptly, followed quickly by celiotomy. During exploratory surgical intervention, copious irrigation and direct wiping with gauze are employed to remove as much barium as possible. Omentectomy should be considered when needed to expedite barium removal. Despite aggressive medical and surgical treatments, postoperative prognosis is guarded to poor due to complications, such as acute vascular shock, sepsis, diffuse peritonitis, hypoproteninemia, electrolyte imbalance, cardiac arrest, small bowel obstruction related to progression of granulomas and adhesions in the abdominal cavity. Therefore, intensive postoperative monitoring and prompt intervention are necessary to maximize chances for a positive outcome. For those that do survive, small bowel obstruction is a potential consequence due to progression of abdominal adhesions. PMID:24430662

  10. Barium uranyl diphosphonates

    SciTech Connect

    Nelson, Anna-Gay D.; Alekseev, Evgeny V.; Ewing, Rodney C.; Albrecht-Schmitt, Thomas E.

    2012-08-15

    Three Ba{sup 2+}/UO{sub 2}{sup 2+} methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200 Degree-Sign C. These compounds, Ba[UO{sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{center_dot}1.4H{sub 2}O (Ba-1), Ba{sub 3}[(UO{sub 2}){sub 4}(CH{sub 2}(PO{sub 3}){sub 2}){sub 2}F{sub 6}]{center_dot}6H{sub 2}O (Ba-2), and Ba{sub 2}[(UO{sub 2}){sub 2}(CH{sub 2}(PO{sub 3}){sub 2})F{sub 4}]{center_dot}5.75H{sub 2}O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO{sub 5}F{sub 2} pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO{sub 2}[CH{sub 2}(PO{sub 3}){sub 2}]{sup 2-} sheets. The interlayer space of the structures is occupied by Ba{sup 2+}, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance. - Graphical abstract: Illustration of the stacking of the layers in Ba{sub 3}[(UO{sub 2}){sub 4}(CH{sub 2}(PO{sub 3}){sub 2}){sub 2})F{sub 6}]{center_dot}6H{sub 2}O viewed along the c-axis. The structure is constructed from UO{sub 7} pentagonal bipyramidal units, U(1)O{sub 7}=gray, U(2)O{sub 7}=yellow, barium=blue, phosphorus=magenta, fluorine=green, oxygen=red, carbon=black, and hydrogen=light peach. Highlights: Black-Right-Pointing-Pointer The polymerization of the UO{sub 2}{sup 2+} sites to form uranyl dimers leads to structural variations in compounds. Black-Right-Pointing-Pointer Barium cations stitch uranyl diphosphonate anionic layers together, and help mediate structure formation. Black-Right-Pointing-Pointer HF acts as both a

  11. Barium uranyl diphosphonates

    NASA Astrophysics Data System (ADS)

    Nelson, Anna-Gay D.; Alekseev, Evgeny V.; Ewing, Rodney C.; Albrecht-Schmitt, Thomas E.

    2012-08-01

    Three Ba2+/UO22+ methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200 °C. These compounds, Ba[UO2[CH2(PO3)2]·1.4H2O (Ba-1), Ba3[(UO2)4(CH2(PO3)2)2F6]·6H2O (Ba-2), and Ba2[(UO2)2(CH2(PO3)2)F4]·5.75H2O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO5F2 pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO2[CH2(PO3)2]2- sheets. The interlayer space of the structures is occupied by Ba2+, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance.

  12. On Barium Oxide Solubility in Barium-Containing Chloride Melts

    NASA Astrophysics Data System (ADS)

    Nikolaeva, Elena V.; Zakiryanova, Irina D.; Bovet, Andrey L.; Korzun, Iraida V.

    2016-08-01

    Oxide solubility in chloride melts depends on temperature and composition of molten solvent. The solubility of barium oxide in the solvents with barium chloride content is essentially higher than that in molten alkali chlorides. Spectral data demonstrate the existence of oxychloride ionic groupings in such melts. This work presents the results of the BaO solubility in two molten BaCl2-NaCl systems with different barium chloride content. The received data together with earlier published results revealed the main regularities of BaO solubility in molten BaO-BaCl2-MCl systems.

  13. Surfactant control of air-sea gas exchange across contrasting biogeochemical regimes

    NASA Astrophysics Data System (ADS)

    Pereira, Ryan; Schneider-Zapp, Klaus; Upstill-Goddard, Robert

    2014-05-01

    Air-sea gas exchange is important to the global partitioning of CO2.Exchange fluxes are products of an air-sea gas concentration difference, ΔC, and a gas transfer velocity, kw. The latter is controlled by the rate of turbulent diffusion at the air-sea interface but it cannot be directly measured and has a high uncertainty that is now considered one of the greatest challenges to quantifying net global air-sea CO2 exchange ...(Takahashi et al., 2009). One important control on kw is exerted by sea surface surfactants that arise both naturally from biological processes and through anthropogenic activity. They influence gas exchange in two fundamental ways: as a monolayer physical barrier and through modifying sea surface hydrodynamics and hence turbulent energy transfer. These effects have been demonstrated in the laboratory with artificial surfactants ...(Bock et al., 1999; Goldman et al., 1988) and through purposeful surfactant releases in coastal waters .(.).........().(Brockmann et al., 1982) and in the open ocean (Salter et al., 2011). Suppression of kwin these field experiments was ~5-55%. While changes in both total surfactant concentration and the composition of the natural surfactant pool might be expected to impact kw, the required in-situ studies are lacking. New data collected from the coastal North Sea in 2012-2013 shows significant spatio-temporal variability in the surfactant activity of organic matter within the sea surface microlayer that ranges from 0.07-0.94 mg/L T-X-100 (AC voltammetry). The surfactant activities show a strong winter/summer seasonal bias and general decrease in concentration with increasing distance from the coastline possibly associated with changing terrestrial vs. phytoplankton sources. Gas exchange experiments of this seawater using a novel laboratory tank and gas tracers (CH4 and SF6) demonstrate a 12-45% reduction in kw compared to surfactant-free water. Seasonally there is higher gas exchange suppression in the summer

  14. Regional Contrasts of the Warming Rate over Land Significantly Depend on the Calculation Methods of Mean Air Temperature

    PubMed Central

    Wang, Kaicun; Zhou, Chunlüe

    2015-01-01

    Global analyses of surface mean air temperature (Tm) are key datasets for climate change studies and provide fundamental evidences for global warming. However, the causes of regional contrasts in the warming rate revealed by such datasets, i.e., enhanced warming rates over the northern high latitudes and the “warming hole” over the central U.S., are still under debate. Here we show these regional contrasts depend on the calculation methods of Tm. Existing global analyses calculate Tm from daily minimum and maximum temperatures (T2). We found that T2 has a significant standard deviation error of 0.23 °C/decade in depicting the regional warming rate from 2000 to 2013 but can be reduced by two-thirds using Tm calculated from observations at four specific times (T4), which samples diurnal cycle of land surface air temperature more often. From 1973 to 1997, compared with T4, T2 significantly underestimated the warming rate over the central U.S. and overestimated the warming rate over the northern high latitudes. The ratio of the warming rate over China to that over the U.S. reduces from 2.3 by T2 to 1.4 by T4. This study shows that the studies of regional warming can be substantially improved by T4 instead of T2. PMID:26198976

  15. Regional Contrasts of the Warming Rate over Land Significantly Depend on the Calculation Methods of Mean Air Temperature

    NASA Astrophysics Data System (ADS)

    Wang, Kaicun; Zhou, Chunlüe

    2015-07-01

    Global analyses of surface mean air temperature (Tm) are key datasets for climate change studies and provide fundamental evidences for global warming. However, the causes of regional contrasts in the warming rate revealed by such datasets, i.e., enhanced warming rates over the northern high latitudes and the “warming hole” over the central U.S., are still under debate. Here we show these regional contrasts depend on the calculation methods of Tm. Existing global analyses calculate Tm from daily minimum and maximum temperatures (T2). We found that T2 has a significant standard deviation error of 0.23 °C/decade in depicting the regional warming rate from 2000 to 2013 but can be reduced by two-thirds using Tm calculated from observations at four specific times (T4), which samples diurnal cycle of land surface air temperature more often. From 1973 to 1997, compared with T4, T2 significantly underestimated the warming rate over the central U.S. and overestimated the warming rate over the northern high latitudes. The ratio of the warming rate over China to that over the U.S. reduces from 2.3 by T2 to 1.4 by T4. This study shows that the studies of regional warming can be substantially improved by T4 instead of T2.

  16. [Food environment and space accessibility evaluation to perform physical activity in 3 socially contrasting neighbourhoods of Buenos Aires city].

    PubMed

    Garipe, Leila Yasmin; Gónzalez, Verónica; Biasizzo, Antonella; Soriano, Jennifer Laila; Perman, Gaston; Giunta, Diego

    2014-01-01

    Due to the environmental influences on health, the goal of this study was to describe and compare the built environment in 3 socially contrasting neighbourhoods of Buenos Aires city.In 2011 a cross-sectional study was conducted in 3 socially contrasting neighbourhoods of Buenos Aires city: Recoleta (upper class), Almagro (middle class) and Constitución (lower class). Grocery stores and food stands were surveyed as well as all suitable spaces to perform physical activity. An analysis was conducted to assess the density of every food outlet per Km2 of each neighbourhood's area and per 10000 inhabitants. 2778 food stores and 149 outdoor physical activity facilities were surveyed. A higher density was observed in Constitución for fast food restaurants (Recoleta 3.6; Almagro 2.4; Constitución 6.7) and food stands (Recoleta 4.2; Almagro 1.2; Constitución 25.7) and a lower density for outdoor physical activity facilities. Population density and area density proved to be analogous. Statistically relevant differences were observed regarding the dimension of each food outlet: grocery stores, fruit stands, pubs, restaurants and food stands, as well as in the number of food stores and outdoor physical activity facilities. The information gathered in this study could be highly useful for public health policies on healthy lifestyles, and could eventually redefine the built environment in order to improve the city's equality regarding outdoor physical activity facilities and food stores. PMID:25647550

  17. Regional Contrasts of the Warming Rate over Land Significantly Depend on the Calculation Methods of Mean Air Temperature

    NASA Astrophysics Data System (ADS)

    Wang, Kaicun; Zhou, Chunlüe

    2016-04-01

    Global analyses of surface mean air temperature (Tm) are key datasets for climate change studies and provide fundamental evidences for global warming. However, the causes of regional contrasts in the warming rate revealed by such datasets, i.e., enhanced warming rates over the northern high latitudes and the "warming hole" over the central U.S., are still under debate. Here we show these regional contrasts depends on the calculation methods of Tm. Existing global analyses calculated Tm from daily minimum and maximum temperatures (T2). We found that T2 has a significant standard deviation error of 0.23 °C/decade in depicting the regional warming rate from 2000 to 2013 but can be reduced by two-thirds using Tm calculated from observations at four specific times (T4), which samples diurnal cycle of land surface air temperature more often. From 1973 to 1997, compared with T4, T2 significantly underestimated the warming rate over the central U.S. and overestimated the warming rate over the northern high latitudes. The ratio of the warming rate over China to that over the U.S. reduces from 2.3 by T2 to 1.4 by T4. This study shows that the studies of regional warming can be substantially improved by T4 instead of T2.

  18. Regional Contrasts of the Warming Rate over Land Significantly Depend on the Calculation Methods of Mean Air Temperature.

    PubMed

    Wang, Kaicun; Zhou, Chunlüe

    2015-01-01

    Global analyses of surface mean air temperature (T(m)) are key datasets for climate change studies and provide fundamental evidences for global warming. However, the causes of regional contrasts in the warming rate revealed by such datasets, i.e., enhanced warming rates over the northern high latitudes and the "warming hole" over the central U.S., are still under debate. Here we show these regional contrasts depend on the calculation methods of T(m). Existing global analyses calculate T(m) from daily minimum and maximum temperatures (T2). We found that T2 has a significant standard deviation error of 0.23 °C/decade in depicting the regional warming rate from 2000 to 2013 but can be reduced by two-thirds using T(m) calculated from observations at four specific times (T4), which samples diurnal cycle of land surface air temperature more often. From 1973 to 1997, compared with T4, T2 significantly underestimated the warming rate over the central U.S. and overestimated the warming rate over the northern high latitudes. The ratio of the warming rate over China to that over the U.S. reduces from 2.3 by T2 to 1.4 by T4. This study shows that the studies of regional warming can be substantially improved by T4 instead of T2. PMID:26198976

  19. Dose perturbations due to contrast medium and air in MammoSite registered treatment: An experimental and Monte Carlo study

    SciTech Connect

    Cheng, C.-W.; Mitra, R.; Allen Li, X.; Das, Indra J.

    2005-07-15

    In the management of early breast cancer, a partial breast irradiation technique called MammoSite registered (Proxima Therapeutic Inc., Alpharetta, GA) has been advocated in recent years. In MammoSite, a balloon implanted at the surgical cavity during tumor excision is filled with a radio-opaque solution, and radiation is delivered via a high dose rate brachytherapy source situated at the center of the balloon. Frequently air may be introduced during placement of the balloon and/or injection of the contrast solution into the balloon. The purpose of this work is to quantify as well as to understand dose perturbations due to the presence of a high-Z contrast medium and/or an air bubble with measurements and Monte Carlo calculations. In addition, the measured dose distribution is compared with that obtained from a commercial treatment planning system (Nucletron PLATO system). For a balloon diameter of 42 mm, the dose variation as a function of distance from the balloon surface is measured for various concentrations of a radio-opaque solution (in the range 5%-25% by volume) with a small volume parallel plate ion chamber and a micro-diode detector placed perpendicular to the balloon axis. Monte Carlo simulations are performed to provide a basic understanding of the interaction mechanism and the magnitude of dose perturbation at the interface near balloon surface. Our results show that the radio-opaque concentration produces dose perturbation up to 6%. The dose perturbation occurs mostly within the distances <1 mm from the balloon surface. The Plato system that does not include heterogeneity correction may be sufficient for dose planning at distances {>=}10 mm from the balloon surface for the iodine concentrations used in the MammoSite procedures. The dose enhancement effect near the balloon surface (<1 mm) due to the higher iodine concentration is not correctly predicted by the Plato system. The dose near the balloon surface may be increased by 0.5% per cm{sup 3} of air

  20. High spatiotemporal resolution measurement of regional lung air volumes from 2D phase contrast x-ray images

    SciTech Connect

    Leong, Andrew F. T.; Islam, M. Sirajul; Kitchen, Marcus J.; Fouras, Andreas; Wallace, Megan J.; Hooper, Stuart B.

    2013-04-15

    Purpose: Described herein is a new technique for measuring regional lung air volumes from two-dimensional propagation-based phase contrast x-ray (PBI) images at very high spatial and temporal resolution. Phase contrast dramatically increases lung visibility and the outlined volumetric reconstruction technique quantifies dynamic changes in respiratory function. These methods can be used for assessing pulmonary disease and injury and for optimizing mechanical ventilation techniques for preterm infants using animal models. Methods: The volumetric reconstruction combines the algorithms of temporal subtraction and single image phase retrieval (SIPR) to isolate the image of the lungs from the thoracic cage in order to measure regional lung air volumes. The SIPR algorithm was used to recover the change in projected thickness of the lungs on a pixel-by-pixel basis (pixel dimensions {approx}16.2 {mu}m). The technique has been validated using numerical simulation and compared results of measuring regional lung air volumes with and without the use of temporal subtraction for removing the thoracic cage. To test this approach, a series of PBI images of newborn rabbit pups mechanically ventilated at different frequencies was employed. Results: Regional lung air volumes measured from PBI images of newborn rabbit pups showed on average an improvement of at least 20% in 16% of pixels within the lungs in comparison to that measured without the use of temporal subtraction. The majority of pixels that showed an improvement was found to be in regions occupied by bone. Applying the volumetric technique to sequences of PBI images of newborn rabbit pups, it is shown that lung aeration at birth can be highly heterogeneous. Conclusions: This paper presents an image segmentation technique based on temporal subtraction that has successfully been used to isolate the lungs from PBI chest images, allowing the change in lung air volume to be measured over regions as small as the pixel size. Using

  1. CH Stars and Barium Stars

    NASA Astrophysics Data System (ADS)

    Bond, H.; Sion, E.; Murdin, P.

    2000-11-01

    The classical barium (or `Ba II') stars are RED GIANT STARS whose spectra show strong absorption lines of barium, strontium and certain other heavy elements, as well as strong features due to carbon molecules. Together with the related class of CH stars, the Ba II stars were crucial in establishing the existence of neutron-capture reactions in stellar interiors that are responsible for the synt...

  2. Barium light source method and apparatus

    NASA Technical Reports Server (NTRS)

    Curry, John J. (Inventor); MacDonagh-Dumler, Jeffrey (Inventor); Anderson, Heidi M. (Inventor); Lawler, James E. (Inventor)

    2002-01-01

    Visible light emission is obtained from a plasma containing elemental barium including neutral barium atoms and barium ion species. Neutral barium provides a strong green light emission in the center of the visible spectrum with a highly efficient conversion of electrical energy into visible light. By the selective excitation of barium ionic species, emission of visible light at longer and shorter wavelengths can be obtained simultaneously with the green emission from neutral barium, effectively providing light that is visually perceived as white. A discharge vessel contains the elemental barium and a buffer gas fill therein, and a discharge inducer is utilized to induce a desired discharge temperature and barium vapor pressure therein to produce from the barium vapor a visible light emission. The discharge can be induced utilizing a glow discharge between electrodes in the discharge vessel as well as by inductively or capacitively coupling RF energy into the plasma within the discharge vessel.

  3. Interaction between Barium Oxide and Barium Containing Chloride Melt

    NASA Astrophysics Data System (ADS)

    Nikolaeva, Elena V.; Zakiryanova, Irina D.; Korzun, Iraida V.; Bovet, Andrey L.; Antonov, Boris D.

    2015-05-01

    Thermal analysis was applied to determine the liquidus temperatures in the NaCl-KCl-BaCl2-BaO system, with BaO concentration varied from 0 to 6 mole%. The temperature dependence of the BaO solubility in the NaCl-KCl-BaCl2 eutectic melt was investigated; the thermodynamic parameters of BaO dissolution were calculated. The caloric effects of melting of the NaCl-KCl-BaCl2 eutectic with barium oxide and barium oxychloride additions were studied. The type, morphology, and composition of oxychloride ionic groupings in the melt were determined in situ using Raman spectroscopy.

  4. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  5. Preparation and in vitro evaluation of poly(D,L-lactide-co-glycolide) air-filled nanocapsules as a contrast agent for ultrasound imaging.

    PubMed

    Néstor, Mendoza-Muñoz; Kei, Noriega-Peláez Eddy; Guadalupe, Nava-Arzaluz María; Elisa, Mendoza-Elvira Susana; Adriana, Ganem-Quintanar; David, Quintanar-Guerrero

    2011-10-01

    The aim of this study was to prepare air-filled nanocapsules intended ultrasound contrast agents (UCAs) with a biodegradable polymeric shell composed of poly(d,l-lactide-co-glycolide) (PLGA). Because of their size, current commercial UCAs are not capable of penetrating the irregular vasculature that feeds growing tumors. The new generation of UCAs should be designed on the nanoscale to enhance tumor detection, in addition, the polymeric shell in contrast with monomolecular stabilized UCAs improves the mechanical properties against ultrasound pressure and lack of stability. The preparation method of air-filled nanocapsules was based on a modification of the double-emulsion solvent evaporation technique. Air-filled nanocapsules with a mean diameter of 370±96nm were obtained. Electronic microscopies revealed spherical-shaped particles with smooth surfaces and a capsular morphology, with a shell thickness of ∼50nm. Air-filled nanocapsules showed echogenic power in vitro, providing an enhancement of up to 15dB at a concentration of 0.045mg/mL at a frequency of 10MHz. Loss of signal for air-filled nanocapsules was 2dB after 30min, suggesting high stability. The prepared contrast agent in this work has the potential to be used in ultrasound imaging. PMID:21570702

  6. Barium swallow study in routine clinical practice: a prospective study in patients with chronic cough*,**

    PubMed Central

    Nin, Carlos Shuler; Marchiori, Edson; Irion, Klaus Loureiro; Paludo, Artur de Oliveira; Alves, Giordano Rafael Tronco; Hochhegger, Daniela Reis; Hochhegger, Bruno

    2013-01-01

    OBJECTIVE: To assess the routine use of barium swallow study in patients with chronic cough. METHODS: Between October of 2011 and March of 2012, 95 consecutive patients submitted to chest X-ray due to chronic cough (duration > 8 weeks) were included in the study. For study purposes, additional images were obtained immediately after the oral administration of 5 mL of a 5% barium sulfate suspension. Two radiologists systematically evaluated all of the images in order to identify any pathological changes. Fisher's exact test and the chi-square test for categorical data were used in the comparisons. RESULTS: The images taken immediately after barium swallow revealed significant pathological conditions that were potentially related to chronic cough in 12 (12.6%) of the 95 patients. These conditions, which included diaphragmatic hiatal hernia, esophageal neoplasm, achalasia, esophageal diverticulum, and abnormal esophageal dilatation, were not detected on the images taken without contrast. After appropriate treatment, the symptoms disappeared in 11 (91.6%) of the patients, whereas the treatment was ineffective in 1 (8.4%). We observed no complications related to barium swallow, such as contrast aspiration. CONCLUSIONS: Barium swallow improved the detection of significant radiographic findings related to chronic cough in 11.5% of patients. These initial findings suggest that the routine use of barium swallow can significantly increase the sensitivity of chest X-rays in the detection of chronic cough-related etiologies. PMID:24473762

  7. The problem of the barium stars

    NASA Technical Reports Server (NTRS)

    Bohm-Vitense, E.; Nemec, J.; Proffitt, C.

    1984-01-01

    Ultraviolet observations of barium stars and other cool stars with peculiar element abundances are reported. Those observations attempted to find hot white dwarf companions. Among six real barium stars studied, only Zeta Cap was found to have a white dwarf companion. Among seven mild, or marginal, barium stars studied, at least three were found to have hot subluminous companions. It is likely that all of them have white dwarf companions.

  8. Barium Depletion in Hollow Cathode Emitters

    NASA Technical Reports Server (NTRS)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  9. The use of carbon dioxide as an insufflation agent in barium enema--does it have a role?

    PubMed

    Robson, N K; Lloyd, M; Regan, F

    1993-03-01

    A double blind prospective study was undertaken to evaluate the benefit of using carbon dioxide in double contrast barium enema (DCBE). 142 consecutive patients referred for DCBE were randomly allocated to receive either air or carbon dioxide (CO2) as the insufflation agent. The use of CO2 reduced the incidence of immediate and delayed severe pain from 31% to 12.5% and from 12.9% to 4.2% respectively. There was a statistically significant higher incidence of delayed severe pain in the younger age group as found in previous studies. Post-evacuation films showed that there was less residual gas after CO2. The quality of the DCBE was unchanged. We urge the more widespread use of CO2 as insufflation agent in DCBE. PMID:8472110

  10. Visualisation of the temporary cavity by computed tomography using contrast material.

    PubMed

    Schyma, Christian; Hagemeier, Lars; Greschus, Susanne; Schild, Hans; Madea, Burkhard

    2012-01-01

    The temporary cavity of a missile produces radial tears in ordnance gelatine, which correlate to the energy transfer. Computed tomography is a useful and non-destructive method to examine gelatine blocks. However, the tears give only few radiocontrast by air filling, which decreases with the time past shooting. Therefore, systematically, a radiocontrast material was searched to enhance the contrast. Different contrast materials were amalgamated to acryl paint, and about 7 g was sealed in a foil bag, which was integrated in the front of a standard 10% gelatine cylinder. Shots with Action-5 expanding bullets were performed from a 5-m distance. Gelatine was scanned by multi-slice computed tomography. The multiplanar reconstructed images were compared to mechanically cut slices of 1 cm thickness. It was shown experimentally that iodine containing water-soluble contrast material did not give sufficient contrast and caused diffusion artefacts. Best results were obtained by barium sulphate emulsion. The amount of acryl paint was sufficient to colour the tears for optical scanning. The radiocontrast of barium leads to satisfying imaging of tears and allowed the creation of a three-dimensional reconstruction of the temporary cavity. Comparison of optical and radiological results showed an excellent correlation, but absolute measures in computed tomographic (CT) images remained lower compared with optically gathered values in the gelatine slices. Combination of paint and contrast material for CT examination will facilitate the evaluation of complex ballistic models and increase accuracy. PMID:21437598

  11. Processing science of barium titanate

    NASA Astrophysics Data System (ADS)

    Aygun, Seymen Murat

    Barium titanate and barium strontium titanate thin films were deposited on base metal foils via chemical solution deposition and radio frequency magnetron sputtering. The films were processed at elevated temperatures for densification and crystallization. Two unifying research goals underpin all experiments: (1) To improve our fundamental understanding of complex oxide processing science, and (2) to translate those improvements into materials with superior structural and electrical properties. The relationships linking dielectric response, grain size, and thermal budget for sputtered barium strontium titanate were illustrated. (Ba 0.6Sr0.4)TiO3 films were sputtered on nickel foils at temperatures ranging between 100-400°C. After the top electrode deposition, the films were co-fired at 900°C for densification and crystallization. The dielectric properties were observed to improve with increasing sputter temperature reaching a permittivity of 1800, a tunability of 10:1, and a loss tangent of less than 0.015 for the sample sputtered at 400°C. The data can be understood using a brick wall model incorporating a high permittivity grain interior with low permittivity grain boundary. However, this high permittivity value was achieved at a grain size of 80 nm, which is typically associated with strong suppression of the dielectric response. These results clearly show that conventional models that parameterize permittivity with crystal diameter or film thickness alone are insufficiently sophisticated. Better models are needed that incorporate the influence of microstructure and crystal structure. This thesis next explores the ability to tune microstructure and properties of chemically solution deposited BaTiO3 thin films by modulation of heat treatment thermal profiles and firing atmosphere composition. Barium titanate films were deposited on copper foils using hybrid-chelate chemistries. An in-situ gas analysis process was developed to probe the organic removal and the

  12. Barium granuloma of the transverse colon.

    PubMed Central

    McKee, P. H.; Cameron, C. H.

    1978-01-01

    A case of barium sulphate granuloma of the transverse colon following gunshot wounds to the abdomen has been described. Scanning electron microscopy with electron probe microanalysis was used to confirm the presence of barium sulphate and the absence of lead or other elements related to the gunshot wounds. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:740599

  13. Contrast in air pollution components between major streets and background locations: Particulate matter mass, black carbon, elemental composition, nitrogen oxide and ultrafine particle number

    NASA Astrophysics Data System (ADS)

    Boogaard, Hanna; Kos, Gerard P. A.; Weijers, Ernie P.; Janssen, Nicole A. H.; Fischer, Paul H.; van der Zee, Saskia C.; de Hartog, Jeroen J.; Hoek, Gerard

    2011-01-01

    Policies to reduce outdoor air pollution concentrations are often assessed on the basis of the regulated pollutants. Whether these are the most appropriate components to assess the potential health benefits is questionable, as other health-relevant pollutants may be more strongly related to traffic. The aim of this study is to compare the contrast in concentration between major roads and (sub)urban background for a large range of pollutants and to analyze the magnitude of the measured difference in the street - background for major streets with different street configurations. Measurements of PM 10, PM 2.5, particle number concentrations (PNC), black carbon (BC), elemental composition of PM 10 and PM 2.5 and NO x were conducted simultaneously in eight major streets and nine (sub)urban background locations in the Netherlands. Measurements were done six times for a week during a six month period in 2008. High contrasts between busy streets and background locations in the same city were found for chromium, copper and iron (factor 2-3). These elements were especially present in the coarse fraction of PM. In addition, high contrasts were found for BC and NO x (factor 1.8), typically indicators of direct combustion emissions. The contrast for PNC was similar to BC. NO 2 contrast was lower (factor 1.5). The largest contrast was found for two street canyons and two streets with buildings at one side of the street only. The contrast between busy streets and urban background in NO 2 was less than the contrast found for BC, PNC and elements indicative of non-exhaust emissions, adding evidence that NO 2 is not representing (current) traffic well. The study supports a substantial role for non-exhaust emissions including brake- and tyre wear and road dust in addition to direct combustion emissions. Significant underestimation of disease burden may occur when relying too much on the regulated components.

  14. A regression-based method for mapping traffic-related air pollution: application and testing in four contrasting urban environments.

    PubMed

    Briggs, D J; de Hoogh, C; Gulliver, J; Wills, J; Elliott, P; Kingham, S; Smallbone, K

    2000-05-15

    Accurate, high-resolution maps of traffic-related air pollution are needed both as a basis for assessing exposures as part of epidemiological studies, and to inform urban air-quality policy and traffic management. This paper assesses the use of a GIS-based, regression mapping technique to model spatial patterns of traffic-related air pollution. The model--developed using data from 80 passive sampler sites in Huddersfield, as part of the SAVIAH (Small Area Variations in Air Quality and Health) project--uses data on traffic flows and land cover in the 300-m buffer zone around each site, and altitude of the site, as predictors of NO2 concentrations. It was tested here by application in four urban areas in the UK: Huddersfield (for the year following that used for initial model development), Sheffield, Northampton, and part of London. In each case, a GIS was built in ArcInfo, integrating relevant data on road traffic, urban land use and topography. Monitoring of NO2 was undertaken using replicate passive samplers (in London, data were obtained from surveys carried out as part of the London network). In Huddersfield, Sheffield and Northampton, the model was first calibrated by comparing modelled results with monitored NO2 concentrations at 10 randomly selected sites; the calibrated model was then validated against data from a further 10-28 sites. In London, where data for only 11 sites were available, validation was not undertaken. Results showed that the model performed well in all cases. After local calibration, the model gave estimates of mean annual NO2 concentrations within a factor of 1.5 of the actual mean (approx. 70-90%) of the time and within a factor of 2 between 70 and 100% of the time. r2 values between modelled and observed concentrations are in the range of 0.58-0.76. These results are comparable to those achieved by more sophisticated dispersion models. The model also has several advantages over dispersion modelling. It is able, for example, to provide

  15. Radium/Barium Waste Project

    SciTech Connect

    McDowell, Allen K.; Ellefson, Mark D.; McDonald, Kent M.

    2015-06-25

    The treatment, shipping, and disposal of a highly radioactive radium/barium waste stream have presented a complex set of challenges requiring several years of effort. The project illustrates the difficulty and high cost of managing even small quantities of highly radioactive Resource Conservation and Recovery Act (RCRA)-regulated waste. Pacific Northwest National Laboratory (PNNL) research activities produced a Type B quantity of radium chloride low-level mixed waste (LLMW) in a number of small vials in a facility hot cell. The resulting waste management project involved a mock-up RCRA stabilization treatment, a failed in-cell treatment, a second, alternative RCRA treatment approach, coordinated regulatory variances and authorizations, alternative transportation authorizations, additional disposal facility approvals, and a final radiological stabilization process.

  16. Barium Isotopes in Single Presolar Grains

    NASA Technical Reports Server (NTRS)

    Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2001-01-01

    Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

  17. Thermochemical hydrogen production via a cycle using barium and sulfur - Reaction between barium sulfide and water

    NASA Technical Reports Server (NTRS)

    Ota, K.; Conger, W. L.

    1977-01-01

    The reaction between barium sulfide and water, a reaction found in several sulfur based thermochemical cycles, was investigated kinetically at 653-866 C. Gaseous products were hydrogen and hydrogen sulfide. The rate determining step for hydrogen formation was a surface reaction between barium sulfide and water. An expression was derived for the rate of hydrogen formation.

  18. Sulphate removal from sodium sulphate-rich brine and recovery of barium as a barium salt mixture.

    PubMed

    Vadapalli, Viswanath R K; Zvimba, John N; Mulopo, Jean; Motaung, Solly

    2013-01-01

    Sulphate removal from sodium sulphate-rich brine using barium hydroxide and recovery of the barium salts has been investigated. The sodium sulphate-rich brine treated with different dosages of barium hydroxide to precipitate barium sulphate showed sulphate removal from 13.5 g/L to less than 400 mg/L over 60 min using a barium to sulphate molar ratio of 1.1. The thermal conversion of precipitated barium sulphate to barium sulphide achieved a conversion yield of 85% using coal as both a reducing agent and an energy source. The recovery of a pure mixture of barium salts from barium sulphide, which involved dissolution of barium sulphide and reaction with ammonium hydroxide resulted in recovery of a mixture of barium carbonate (62%) and barium hydroxide (38%), which is a critical input raw material for barium salts based acid mine drainage (AMD) desalination technologies. Under alkaline conditions of this barium salt mixture recovery process, ammonia gas is given off, while hydrogen sulfide is retained in solution as bisulfide species, and this provides basis for ammonium hydroxide separation and recovery for reuse, with hydrogen sulfide also recoverable for further industrial applications such as sulfur production by subsequent stripping. PMID:23485244

  19. Chemical abundances and kinematics of barium stars

    NASA Astrophysics Data System (ADS)

    de Castro, D. B.; Pereira, C. B.; Roig, F.; Jilinski, E.; Drake, N. A.; Chavero, C.; Silva, J. V. Sales

    2016-04-01

    In this paper we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scale height, radial velocities, abundances of the Na, Al, alpha-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. We found that the metallicities, the temperatures and the surface gravities for barium stars can not be represented by a single gaussian distribution. The abundances of alpha-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heavy-element abundance pattern as given by the ratio [s/Fe], we found that the barium stars present several degrees of enrichment. We also obtained the [hs/ls] ratio by measuring the photospheric abundances of the Ba-peak and the Zr-peak elements. Our results indicated that the [s/Fe] and the [hs/ls] ratios are strongly anti-correlated with the metallicity. Our kinematical analysis showed that 90% of the barium stars belong to the thin disk population. Based on their luminosities, none of the barium stars are luminous enough to be an AGB star, nor to become self-enriched in the s-process elements. Finally, we determined that the barium stars also follow an age-metallicity relation.

  20. Chemical abundances and kinematics of barium stars

    NASA Astrophysics Data System (ADS)

    de Castro, D. B.; Pereira, C. B.; Roig, F.; Jilinski, E.; Drake, N. A.; Chavero, C.; Sales Silva, J. V.

    2016-07-01

    In this paper, we present an homogeneous analysis of photospheric abundances based on high-resolution spectroscopy of a sample of 182 barium stars and candidates. We determined atmospheric parameters, spectroscopic distances, stellar masses, ages, luminosities and scaleheight, radial velocities, abundances of the Na, Al, α-elements, iron-peak elements, and s-process elements Y, Zr, La, Ce, and Nd. We employed the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. We found that the metallicities, the temperatures and the surface gravities for barium stars cannot be represented by a single Gaussian distribution. The abundances of α-elements and iron peak elements are similar to those of field giants with the same metallicity. Sodium presents some degree of enrichment in more evolved stars that could be attributed to the NeNa cycle. As expected, the barium stars show overabundance of the elements created by the s-process. By measuring the mean heavy-element abundance pattern as given by the ratio [s/Fe], we found that the barium stars present several degrees of enrichment. We also obtained the [hs/ls] ratio by measuring the photospheric abundances of the Ba-peak and the Zr-peak elements. Our results indicated that the [s/Fe] and the [hs/ls] ratios are strongly anticorrelated with the metallicity. Our kinematical analysis showed that 90 per cent of the barium stars belong to the thin disc population. Based on their luminosities, none of the barium stars are luminous enough to be an asymptotic giant branch star, nor to become self-enriched in the s-process elements. Finally, we determined that the barium stars also follow an age-metallicity relation.

  1. Constraining the oceanic barium cycle with stable barium isotopes

    NASA Astrophysics Data System (ADS)

    Cao, Zhimian; Siebert, Christopher; Hathorne, Ed C.; Dai, Minhan; Frank, Martin

    2016-01-01

    The distribution of barium (Ba) concentrations in seawater resembles that of nutrients and Ba has been widely used as a proxy of paleoproductivity. However, the exact mechanisms controlling the nutrient-like behavior, and thus the fundamentals of Ba chemistry in the ocean, have not been fully resolved. Here we present a set of full water column dissolved Ba (DBa) isotope (δ137BaDBa) profiles from the South China Sea and the East China Sea that receives large freshwater inputs from the Changjiang (Yangtze River). We find pronounced and systematic horizontal and depth dependent δ137BaDBa gradients. Beyond the river influence characterized by generally light signatures (0.0 to + 0.3 ‰), the δ137BaDBa values in the upper water column are significantly higher (+ 0.9 ‰) than those in the deep waters (+ 0.5 ‰). Moreover, δ137BaDBa signatures are essentially constant in the entire upper 100 m, in which dissolved silicon isotopes are fractionated during diatom growth resulting in the heaviest isotopic compositions in the very surface waters. Combined with the decoupling of DBa concentrations and δ137BaDBa from the concentrations of nitrate and phosphate this implies that the apparent nutrient-like fractionation of Ba isotopes in seawater is primarily induced by preferential adsorption of the lighter isotopes onto biogenic particles rather than by biological utilization. The subsurface δ137BaDBa distribution is dominated by water mass mixing. The application of stable Ba isotopes as a proxy for nutrient cycling should therefore be considered with caution and both biological and physical processes need to be considered. Clearly, however, Ba isotopes show great potential as a new tracer for land-sea interactions and ocean mixing processes.

  2. Surface composition and barium evaporation rate of ``pedigreed'' impregnated tungsten dispenser cathodes during accelerated life testing

    NASA Astrophysics Data System (ADS)

    Tomich, D. H.; Mescher, J. A.; Grant, J. T.

    1987-03-01

    A study has been made of the surface composition and barium evaporation rate of "pedigreed" impregnated tungsten dispenser cathodes. The effect of air exposure on coated cathodes was examined and was found to have no significant effect on barium evaporation rate although in some cases longer reactivation times were required. No changes in surface topography were apparent following air exposure and reactivation. Life testing was done at 100°C above the typical operating temperature for the cathode, where the typical operating temperature was taken to be 950°C for coated cathodes and 1050°C for uncoated cathodes. The cathodes were examined at different stages of life testing, up to 1200 h. Significant decreases in barium evaporation rates were found after as few as 500 h of life testing. After 1000 h the evaporation rate had decreased more than an order of magnitude. Changes in surface composition were also found. The effects of tungsten particle size, used in manufacture of the billet, on barium evaporation rate were also studied but no correlation was found.

  3. Studies of hexacelsian and celsian barium aluminosilicates

    NASA Astrophysics Data System (ADS)

    Lee, Kuo-Tong

    1998-09-01

    The first part of this work (chapter 3) describes the reaction paths leading to the formation of BaAlsb2Sisb2Osb8 (BAS) from a mixture of gamma-BaCOsb3,\\ alpha-Alsb2Osb3, and amorphous SiOsb2 powders. Heat treatments conducted from 600 to 1200sp°C in air were used to transform the powder mixtures into hexacelsian BAS. The phase evolution to BAS was examined by x-ray diffraction. Several experiments were designed to microscopically reproduce the solid-solid interfaces expected during the synthesis of BAS and enabled the author to describe the different stages of the reaction. There exist two reaction paths in formation of BAS in this study: (1) formation of a series of barium silicates leading to BaO*2SiOsb2 (BSsb2) which then reacts with Alsb2Osb3 to form BAS and (2) formation of BaO*Alsb2Osb3 (BA) which then reacts with SiOsb2 to form BAS. The kinetics of the latter is slower than that of the former because the reaction between BaO*Alsb2Osb3 and SiOsb2 to form BAS includes a bond breaking process. The second part (chapter 4) of this research was undertaken to study the role of additives on the kinetics of the transformation of hexacelsian to celsian. Pre-synthesized hexacelsian powders doped with various additives were heated at temperatures ranging from 850 to 1400sp°C for 4 hrs. Semi-quantitative analysis of XRD was used to determine the extent of the hexacelsian-to-celsian transformation. This work was extended further to investigate the mechanisms involved in the transformation. Defect structures developed in the additive-containing celsian provide insights about the sites occupied by the cations added. Experimental results indicate that the doping of ˜0.99A cations in promoting the conversion of hexacelsian to celsian is by forming an interstitial solid solution in hexacelsian and ˜0.66A cations form a substitutional solid solution. In a kinetic study on the CaO- or MgO-enhanced transformation, values of rate constant, k, and Avlami constant, n, at

  4. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  5. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  6. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  7. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  8. 40 CFR 721.10011 - Barium calcium manganese strontium oxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium calcium manganese strontium... Specific Chemical Substances § 721.10011 Barium calcium manganese strontium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium...

  9. Carcinomas of the base of the tongue: diagnosis using double-contrast radiography of the pharynx

    SciTech Connect

    Apter, A.J.; Levine, M.S.; Glick, S.N.

    1984-04-01

    A barium examination is frequently performed as the primary screening study on patients with carcinoma of the base of the tongue who present with dysphagia. Because of the limitations of the conventional barium study in visualizing the pharynx, double-contrast views of this region are routinely included as part of the standard barium examination on all patients with pharyngeal dysphagia. With this technique, six carcinomas of the base of the tongue were detected, including four ulcerating and two exophytic lesions. The normal and abnormal appearance of the tongue base on double-contrast radiography of the pharynx is described.

  10. Contrast studies.

    PubMed

    Anderson, Susan M

    2006-01-01

    Contrast media plays an important role in imaging soft tissues and organs. Though contrast imaging is considered safe, radiologic technologists can improve the safety of contrast examinations by reviewing institutional safety procedures, safe practices for different methods of contrast administration and possible complications. The need for efficient communication and attention to detail during contrast procedures is essential for patient safety. PMID:16998193

  11. Magnetic studies of cobalt doped barium hexaferrite nanoparticles prepared by modified sol-gel method

    NASA Astrophysics Data System (ADS)

    Shalini, M. Govindaraj; Sahoo, Subasa C.

    2016-05-01

    M-type barium hexaferrite (BaFe12O19) and cobalt doped barium hexaferrite (BaFe11CoO19) nanopowders were synthesized by modified sol-gel auto-combustion technique and were annealed at 900°C in air for 4 hours. The annealed powders were studied in the present work and X-ray diffraction studies showed pure phase formation after annealing. The average grain size in the nanopowder sample was decreased after doping. Magnetization value of 60 emu/g was observed at 300K for the barium hexaferrite and was reduced to 54 emu/g after doping. The coercivity of 5586 Oe was observed at 300K for the undoped sample and was found to be decreased in the doped sample. As the measurement temperature was decreased from 300K to 60K, magnetization value was increased in both the samples compared to those at 300K. The coercivity of the undoped sample was found to decrease whereas it was increased for the doped sample at 60K. The observed magnetic properties may be understood on the basis of modified exchange interaction and anisotropy in the doped sample compared to that of pure barium hexaferrite.

  12. 75 FR 19657 - Barium Chloride From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-15

    ... Commission found that the domestic interested party group response to its notice of institution (74 FR 31757... COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Notice of Commission determination to conduct a full five-year review concerning the antidumping duty order on...

  13. 75 FR 20625 - Barium Chloride From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-20

    ... established a schedule for the conduct of this review (74 FR 62587, November 30, 2010). Subsequently, counsel... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Barium Chloride From China AGENCY: United States International Trade Commission. ACTION:...

  14. Analysis of barium hydroxide and calcium hydroxide slurry carbonation reactors

    SciTech Connect

    Patch, K.D.; Hart, R.P.; Schumacher, W.A.

    1980-05-01

    The removal of CO/sub 2/ from air was investigated by using a continuous-agitated-slurry carbonation reactor containing either barium hydroxide (Ba(OH)/sub 2/) or calcium hydroxide (Ca(OH)/sub 2/). Such a process would be applied to scrub /sup 14/CO/sub 2/ from stack gases at nuclear-fuel reprocessing plants. Decontamination factors were characterized for reactor conditions which could alter hydrodynamic behavior. An attempt was made to characterize reactor performance with models assuming both plug flow and various degrees of backmixing in the gas phase. The Ba(OH)/sub 2/ slurry enabled increased conversion, but apparently the process was controlled under some conditions by phenomena differing from those observed for carbonation by Ca(OH)/sub 2/. Overall reaction mechanisms are postulated.

  15. Assessment of the solubility and bioaccessibility of barium and aluminum in soils affected by mine dust deposition.

    PubMed

    Shock, S S; Bessinger, B A; Lowney, Y W; Clark, J L

    2007-07-01

    Barium is a heavy metal to which human and animal receptors may be exposed in various settings--for example, in mineral extraction industries where the mining and milling of ores occurs. Aluminum is also an element abundant in soil and dust to which human and animal receptors may be exposed in association with such industries. This study investigated the solubility and bioaccessibility of barium and aluminum in simulated gastric fluids using an in vitro test method previously validated for lead. Soil samples were collected from the vicinity of a mine and transport road that generated fugitive dust containing barium as barite (BaSO4). It was found that barium bioaccessibility in different tundra soil and fugitive dust source materials varied greatly, between 0.07 and 66.0%, depending on sample location, grain size, solid-to-fluid ratio used in the in vitro experiments, and the analytical method selected for determining total barium concentrations in the sample substrates. For X-ray fluorescence spectrometry (XRF) analytical methods and a solid-to-fluid ratio of 1:100, barium bioaccessibility from the barite-rich mine waste rock and gyro crusher ore dust source materials was very low (0.07-0.36%). By contrast, the bioaccessibility of barium in tundra soil samples affected by fugitive dust deposition ranged from 3.8 to 19.5%. The relative solubility of barium measured in the simulated gastric fluids of this study is consistent with time-dependent dissolution of barite in mine waste rock and ore dust, and the presence of more soluble chemical forms in tundra soil. Laboratory XRF analysis was the only analytical method used in this study that accurately characterized total barium concentrations for all sample substrates. Aluminum bioaccessibility was distinguished from barium bioaccessibility by its generally lower values and smaller dependence on grain size and solid-to-fluid ratios. The range of aluminum bioaccessibility values (0.31-4.0%) is consistent with the

  16. A study of the microchemistry of nanocrystalline barium titanate with tetragonal and pseudocubic room temperature symmetries

    NASA Astrophysics Data System (ADS)

    Lacey, Robert A.

    The investigation of possible effects of undesired surface species on barium titanate, one of the most utilized ferroelectric ceramics, constitutes the focus of this work. Six commercial barium titanate powders from three manufacturers representing two different synthesis processes, with average particle sizes from 40 nm to 470 nm, were analyzed in this study. Four of the nanopowders exhibited pseudocubic room temperature symmetry. Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopic analysis of the nanopowders was conducted in ambient atmosphere at room temperature. High temperature DRIFT followed incorporating four avenues of analysis: moisture adsorption studies, deuterium oxide exchange studies, carbon dioxide adsorption studies, and high temperature analysis under dry air and UHP nitrogen atmospheres. At the highest temperature used in this study, 1173K, moisture and the accompanying incorporated protonic impurities were still present. The powders readily readsorbed moisture during rapid cooling, 170K/minute, to room temperature. The smallest powder, as received, formed spherical agglomerates up to 10 mum diameter. These sintered as separate units attaining diameters up to 60 mum during intermediate stage sintering. X-ray photoelectron spectroscopy indicated a surface contamination layer of 10 A to 18 A; 50--70% of which was barium carbonate, the balance being atmospheric adsorbed species. Samples cooled at 3K/minute after an 1173K calcine retained cubic symmetry as indicated with high temperature X-ray diffraction. However, spectral evidence was obtained indicating that upon the rapid cooling from the 1173K calcine, a reorientation to the room temperature tetragonal symmetry was observed. Further, SEM and TEM supported this finding with visual evidence of interfacial rearrangement including corroborating electron diffraction analysis. This data, therefore, substantiated the hypothesis that the cause of the room temperature pseudocubic

  17. Patterns of cold-air drainage and microclimate in mid-latitude versus high-latitude mountains: contrasts and implications for climate change (Invited)

    NASA Astrophysics Data System (ADS)

    Pepin, N. C.

    2009-12-01

    Predictions of current spatial patterns of climate are difficult in areas of complex relief in all parts of the world, because of the interweaving influences of topography, elevation and aspect. These influences vary temporally as a result of the seasonal and diurnal cycles in radiation balance. In periods of negative energy balance, surface decoupling can occur as cold air drainage develops low-level temperature inversions, and the surface temperature regime beneath the inversion becomes divorced from free atmospheric forcing. Both the spatial scale and temporal persistence of this decoupling vary according to latitude, and although the physical processes that influence inversion formation are similar in polar areas and mid-latitude mountains, the contrasting seasonal and diurnal forcings make the end results very different. Examples are contrasted from detailed field temperature measurements (~50 sites per field area) taken over several years in areas of complex relief in the eastern Pyrenees (~42.5 deg N), the Oregon Cascades (also ~42.5 deg N) and Finnish Lapland (70 deg N and above the Arctic circle). In the former two locations decoupling is mostly diurnally driven, and small-scale topography is important in mediating the effects. Summer decoupling is brief and spatially limited, whereas winter decoupling can be more spatially extensive. There are strong relationships between synoptic conditions, as measured by objective flow indices at the 700 mb level (derived from NCEP/NCAR reanalysis fields) and the patterns of decoupling, which allow us to assess the effects of past and potential future circulation change on spatial patterns of future climate warming. In Finnish Lapland the decoupling regime most clearly approaches the mid-latitude pattern around the equinoxes when there are clear day and night periods. In winter and summer however (the polar night and polar day) with the muting of the diurnal cycle, processes are more poorly understood. Winter cold

  18. Radioactive Barium Ion Trap Based on Metal-Organic Framework for Efficient and Irreversible Removal of Barium from Nuclear Wastewater.

    PubMed

    Peng, Yaguang; Huang, Hongliang; Liu, Dahuan; Zhong, Chongli

    2016-04-01

    Highly efficient and irreversible capture of radioactive barium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, here we propose a concept of barium ion trap based on metal-organic framework (MOF) with a strong barium-chelating group (sulfate and sulfonic acid group) in the pore structures of MOFs. The functionalized MOF-based ion traps can remove >90% of the barium within the first 5 min, and the removal efficiency reaches 99% after equilibrium. Remarkably, the sulfate-group-functionalized ion trap demonstrates a high barium uptake capacity of 131.1 mg g(-1), which surpasses most of the reported sorbents and can selectively capture barium from nuclear wastewater, whereas the sulfonic-acid-group-functionalized ion trap exhibits ultrafast kinetics with a kinetic rate constant k2 of 27.77 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than existing sorbents. Both of the two MOF-based ion traps can capture barium irreversibly. Our work proposes a new strategy to design barium adsorbent materials and provides a new perspective for removing radioactive barium and other radionuclides from nuclear wastewater for environment remediation. Besides, the concrete mechanisms of barium-sorbent interactions are also demonstrated in this contribution. PMID:26999358

  19. AES analysis of barium fluoride thin films

    NASA Astrophysics Data System (ADS)

    Kashin, G. N.; Makhnjuk, V. I.; Rumjantseva, S. M.; Shchekochihin, Ju. M.

    1993-06-01

    AES analysis of thin films of metal fluorides is a difficult problem due to charging and decomposition of such films under electron bombardment. We have developed a simple algorithm for a reliable quantitative AES analysis of metal fluoride thin films (BaF 2 in our work). The relative AES sensitivity factors for barium and fluorine were determined from BaF 2 single-crystal samples. We have investigated the dependence of composition and stability of barium fluoride films on the substrate temperature during film growth. We found that the instability of BaF 2 films grown on GaAs substrates at high temperatures (> 525°C) is due to a loss of fluorine. Our results show that, under the optimal electron exposure conditions, AES can be used for a quantitative analysis of metal fluoride thin films.

  20. Resonance-fluorescence in barium ion clouds

    NASA Astrophysics Data System (ADS)

    Horak, H. G.; Whitaker, R. W.

    1982-09-01

    The problem of resonant-fluorescent scattering of sunlight by a high altitude, plane-parallel, barium ion cloud is solved numerically. Line strengths and profiles are computed using a modified version of the computer program LINEAR (Auer, Heasley and Milkey, 1972). Hyperfine structure of the spectral lines becomes important for very thick layers and is taken into account. Comparisons are made between coherent and completely noncoherent scattering results, and finally the influence of collisions on the radiation field is estimated.

  1. Nanoparticles of barium induce apoptosis in human phagocytes

    PubMed Central

    Mores, Luana; França, Eduardo Luzia; Silva, Núbia Andrade; Suchara, Eliane Aparecida; Honorio-França, Adenilda Cristina

    2015-01-01

    Purpose Nutrients and immunological factors of breast milk are essential for newborn growth and the development of their immune system, but this secretion can contain organic and inorganic toxins such as barium. Colostrum contamination with barium is an important issue to investigate because this naturally occurring element is also associated with human activity and industrial pollution. The study evaluated the administration of barium nanoparticles to colostrum, assessing the viability and functional activity of colostral mononuclear phagocytes. Methods Colostrum was collected from 24 clinically healthy women (aged 18–35 years). Cell viability, superoxide release, intracellular Ca2+ release, and phagocyte apoptosis were analyzed in the samples. Results Treatment with barium lowered mononuclear phagocyte viability, increased superoxide release, and reduced intracellular calcium release. In addition, barium increased cell death by apoptosis. Conclusion These data suggest that nanoparticles of barium in colostrum are toxic to cells, showing the importance of avoiding exposure to this element. PMID:26451108

  2. Barium Titanate Nanoparticles for Biomarker Applications

    NASA Astrophysics Data System (ADS)

    Matar, O.; Posada, O. M.; Hondow, N. S.; Wälti, C.; Saunders, M.; Murray, C. A.; Brydson, R. M. D.; Milne, S. J.; Brown, A. P.

    2015-10-01

    A tetragonal crystal structure is required for barium titanate nanoparticles to exhibit the nonlinear optical effect of second harmonic light generation (SHG) for use as a biomarker when illuminated by a near-infrared source. Here we use synchrotron XRD to elucidate the tetragonal phase of commercially purchased tetragonal, cubic and hydrothermally prepared barium titanate (BaTiO3) nanoparticles by peak fitting with reference patterns. The local phase of individual nanoparticles is determined by STEM electron energy loss spectroscopy (EELS), measuring the core-loss O K-edge and the Ti L3-edge energy separation of the t2g, eg peaks. The results show a change in energy separation between the t2g and eg peak from the surface and core of the particles, suggesting an intraparticle phase mixture of the barium titanate nanoparticles. HAADF-STEM and bright field TEM-EDX show cellular uptake of the hydrothermally prepared BaTiO3 nanoparticles, highlighting the potential for application as biomarkers.

  3. Magnetoelastic coupling in epitaxial cobalt ferrite/barium titanate heterostructures

    NASA Astrophysics Data System (ADS)

    Gräfe, Joachim; Welke, Martin; Bern, Francis; Ziese, Michael; Denecke, Reinhard

    2013-08-01

    Ultra-thin cobalt ferrite films have been synthesised on ferroelectric barium titanate crystals. The cobalt ferrite films exhibit a magnetic response to strain induced by structural changes in the barium titanate substrate, suggesting a pathway to multiferroic coupling. These structural changes are achieved by heating through the phase transition temperatures of barium titanate. In addition the ferromagnetic signal of the substrate itself is taken into account, addressing the influence of impurities or defects in the substrate. The cobalt ferrite/barium titanate heterostructure is a suitable oxidic platform for future magnetoelectric applications with an established ferroelectric substrate and widely tuneable magnetic properties by changing the transition metal in the ferrite film.

  4. Lanthanide doped strontium-barium cesium halide scintillators

    SciTech Connect

    Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

    2015-06-09

    The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

  5. Creating unstable velocity-space distributions with barium injections

    NASA Technical Reports Server (NTRS)

    Pongratz, M. B.

    1983-01-01

    Ion velocity-space distributions resulting from barium injections from orbiting spacecraft and shaped charges are discussed. Active experiments confirm that anomalous ionization processes may operate, but photoionization accounts for the production of the bulk of the barium ions. Pitch-angle diffusion and/or velocity-space diffusion may occur, but observations of barium ions moving upwards against gravity suggests that the ions retain a significant enough fraction of their initial perpendicular velocity to provide a mirror force. The barium ion plasmas should have a range of Alfven Mach numbers and plasma betas. Because the initial conditions can be predicted these active experiments should permit testing plasma instability hypotheses.

  6. Barium iron arsenide, barium cobalt arsenide, barium nickel arsenide single crystals and superconductivity upon cobalt doping

    SciTech Connect

    Ronning, Filip; Sefat, A S; Mcguire, M M; Sales, B; Jin, R; Mandrus, D

    2009-01-01

    The crystal structure and physical properties of BaFe{sub 2}As{sub 2}, BaCo{sub 2}As{sub 2}, and BaNi{sub 2}As{sub 2} single crystals are surveyed. BaFe{sub 2}As{sub 2} gives a magnetic and structural transition at T{sub N} = 132(1) K, BaCo{sub 2}As{sub 2} is a paramagnetic metal, while BaNi{sub 2}As{sub 2} has a structural phase transition at T{sub 0} = 131 K, followed by superconductivity below {Tc} = 0.69 K. The bulk superconductivity in Co-doped BaFe{sub 2}As{sub 2} below {Tc} = 22 K is demonstrated by resistivity, magnetic susceptibility, and specific heat data. In contrast to the cuprates, the Fe-based system appears to tolerate considerable disorder in the transition metal layers. First principles calculations for BaFe{sub 1.84}Co{sub 0.16}As{sub 2} inter-band scattering due to Co is weak.

  7. Barium Enhancement in NGC 6819 Blue Stragglers

    NASA Astrophysics Data System (ADS)

    Milliman, Katelyn; Mathieu, Robert D.; Schuler, Simon C.

    2015-01-01

    Possible formation pathways for blue straggler stars include mergers in hierarchical triple systems, stellar collisions during dynamical encounters, and mass transfer from a giant companion. Extensive work on the blue stragglers in the old open cluster NGC 188 (7 Gyr) has led to exciting discoveries including a binary secondary mass distribution peaked at 0.5 MSolar and the detection of three young white dwarf binary companions. These indicate that mass transfer from an asymptotic giant branch star is the dominant mechanism for blue straggler formation in open clusters. Such mass transfer events should pollute the surface abundance of the blue straggler with nucleosynthesis products from the evolved donor. The other formation pathways, mergers and collisions, are predicted to produce no such enhancements. In an effort to move beyond NGC 188 and into other open clusters we present the first results of a surface abundance study of the blue stragglers in the intermediate-aged open cluster NGC 6819 (2.5 Gyr) using the Hydra multi-object spectrograph on the WIYN 3.5 m telescope. This part of our study centers on the s-process element barium as a tracer of formation via mass transfer. We compare the blue straggler surface abundance of barium to that of a sample of main-sequence stars in NGC 6819 and find multiple blue stragglers with anomalous abundances. Surprising, most of the blue stragglers with barium anomalies show no radial-velocity evidence for a companion. We gratefully acknowledge funding from the National Science Foundation under grant AST- 0908082 and the Wisconsin Space Grant Consortium.

  8. BARIUM IN TEETH AS INDICATOR OF BODY BURDEN

    EPA Science Inventory

    A study was conducted to determine the biological availability of naturally occurring barium in a municipal drinking water by the analysis of barium in deciduous teeth of children. The grade school children of two Illinois towns were chosen for the study. The towns were chosen ba...

  9. Barium dithionate as an EPR dosemeter.

    PubMed

    Baran, M P; Bugay, O A; Kolesnik, S P; Maksimenko, V M; Teslenko, V V; Petrenko, T L; Desrosiers, M F

    2006-01-01

    Electron paramagnetic resonance (EPR) dosimetry is growing in popularity and this success has encouraged the search for other dosimetric materials. Previous studies of gamma-irradiated barium dithionate (BaS(2)O(6) x 2H(2)O) have shown promise for its use as a radiation dosemeter. This work studies in greater detail several essential attributes of the system. Special attention has been directed to the study of EPR response dependences on microwave power, irradiation temperature, minimum detectable dose and post-irradiation stability. PMID:16565205

  10. Europium-doped barium bromide iodide

    SciTech Connect

    Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.

    2009-10-21

    Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.

  11. Short-cavity squeezing in barium

    NASA Technical Reports Server (NTRS)

    Hope, D. M.; Bachor, H-A.; Manson, P. J.; Mcclelland, D. E.

    1992-01-01

    Broadband phase sensitive noise and squeezing were experimentally observed in a system of barium atoms interacting with a single mode of a short optical cavity. Squeezing of 13 +/- 3 percent was observed. A maximum possible squeezing of 45 +/- 8 percent could be inferred for out experimental conditions, after correction for measured loss factors. Noise reductions below the quantum limit were found over a range of detection frequencies 60-170 MHz and were best for high cavity transmission and large optical depths. The amount of squeezing observed is consistent with theoretical predictions from a full quantum statistical model of the system.

  12. Vacancy ordering in reduced barium titanate

    NASA Astrophysics Data System (ADS)

    Woodward, David I.; Reaney, Ian M.; Yang, Gaiying Y.; Dickey, Elizabeth C.; Randall, Clive A.

    2004-06-01

    A crystal structure is proposed for reduced barium titanate, BaTiO3-δ, δ≈0.33, formed during the degradation of Ni-BaTiO3 X7R multilayer ceramic capacitors. High-resolution transmission electron microscopy and selected-area electron diffraction have been used in combination with computer simulations to show that oxygen vacancies accrete on every third pseudocubic {111} plane, resulting in a cell with space group P3m1. Additionally, from electron energy loss spectroscopy, it is proposed that Ti4+ is reduced to Ti3+ as a mechanism of charge compensation within oxygen-deficient octahedra.

  13. Barium cardiotoxicity: Relationship between ultrastructural damage and mechanical effects.

    PubMed

    Delfino, G; Amerini, S; Mugelli, A

    1988-01-01

    The ultrastructural damage in guinea-pig ventricular strips caused by barium was analysed. At a concentration of 1 mmol/litre, barium chloride caused a dramatic increase in the developed tension associated with the onset of automaticity. The ultrastructural analysis demonstrated that barium caused notable and consistent alterations which affected most myocyte components. Various degenerative aspects were observed in mitochondria and in the contractile apparatus. Glycogen deposits were completely depleted. Preparations driven at 4 Hz (i.e. the rate of spontaneous firing of barium-treated preparations) showed moderate ultrastructural alterations, thus demonstrating that the increase in the rate of beating is not the only determinant of the observed damage. These results suggest that the myocardial toxicity of barium is due not only to the well-known modifications in membrane permeability, but possibly also to alterations in cell function. PMID:20702358

  14. Emission analysis of a laser-produced barium plasma plume.

    PubMed

    Singh, R K; Joshi, H C; Kumar, Ajai

    2015-09-01

    In the present work we report the characteristic emission features of a laser-produced barium plasma plume. The time-resolved analysis for the different spectral lines of neutral and singly charged ionic barium has been carried out. It has been observed that the temporal evolution of electron temperature and density shows a peculiar behavior which is significantly different from the reported results of laser ablation of materials. The electron density increases with increase in delay time but the temperature does not change to any significant extent. Strong self-reversal in the emission of a resonant singly charged barium ionic line (455.4 nm) with time delay indicates the increase of population of singly charged barium ion with time. The results are explained on the basis of the increased population of barium metastables and subsequent ionization (Penning type). PMID:26368891

  15. Contrastive Lexicology.

    ERIC Educational Resources Information Center

    Hartmann, R. R. K.

    This paper deals with the relation between etymologically related words in different languages. A survey is made of seven stages in the development of contrastive lexicology. These are: prelinguistic word studies, semantics, lexicography, translation, foreign language learning, bilingualism, and finally contrastive analysis. Concerning contrastive…

  16. Proton conductivity of potassium doped barium zirconates

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoxiang; Tao, Shanwen; Irvine, John T. S.

    2010-01-01

    Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10%. Introducing extra potassium leads to the formation of second phase or YSZ impurities. The water uptake of barium zirconates was increased even with 5% doping of potassium at the A-site. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. The maximum solubility for yttrium at B-sites is around 15 at% after introducing 1 wt% zinc. The conductivity of Ba 0.95K 0.05Zr 0.85Y 0.11Zn 0.04O 3-δ at 600 °C is 2.2×10 -3 S/cm in wet 5% H 2. The activation energies for bulk and grain boundary are 0.29(2), 0.79(2) eV in wet 5% H 2 and 0.31(1), 0.74(3) eV in dry 5% H 2. A power density of 7.7 mW/cm 2 at 718 °C was observed when a 1 mm thick Ba 0.95K 0.05Zr 0.85Y 0.11Zn 0.04O 3-δ pellet was used as electrolyte and platinum electrodes.

  17. Contrast Materials

    MedlinePlus

    ... or other reactions to contrast materials are rare, radiology departments are well-equipped to deal with them. ... is given. However, both the American College of Radiology (ACR) and the European Society of Urogenital Radiology ...

  18. Microcapsules with Intrinsic Barium Radiopacity for Immunoprotection and X-ray/CT imaging of Pancreatic Islet Cells

    PubMed Central

    Arifin, D.R.; Manek, S.; Call, E.; Arepally, A.; Bulte, J.W.M.

    2012-01-01

    Microencapsulation is a commonly used technique for immunoprotection of engrafted therapeutic cells. We investigated a library of capsule formulations to determine the most optimal formulation for pancreatic beta islet cell transplantation, using barium as the gelating ion and clinical-grade protamine sulfate (PS) as a new cationic capsule cross-linker. Barium-gelated alginate/PS/alginate microcapsules (APSA, diameter = 444±21 μm) proved to be mechanically stronger and supported a higher cell viability as compared to conventional alginate/poly-L-lysine/alginate (APLLA) capsules. Human pancreatic islets encapsulated inside APSA capsules, gelated with 20 mM barium as optimal concentration, exhibited a sustained morphological integrity, viability, and functionality for at least 3–4 weeks in vitro, with secreted human C-peptide levels of 0.2–160 pg/ml/islet. Unlike APLLA capsules that are gelled with calcium, barium-APSA capsules are intrinsically radiopaque and, when engrafted into mice, could be readily imaged in vivo with micro-computed tomography (CT). Without the need of adding contrast agents, these capsules offer a clinically applicable alternative for simultaneous immunoprotection and real-time, non-invasive X-ray/CT monitoring of engrafted cells during and after in vivo administration. PMID:22444642

  19. Do all barium stars have a white dwarf companion?

    NASA Technical Reports Server (NTRS)

    Dominy, J. F.; Lambert, D. L.

    1983-01-01

    International Ultraviolet Explorer short-wavelength, low-dispersion spectra were analyzed for four barium, two mild barium, and one R-type carbon star in order to test the hypothesis that the barium and related giants are produced by mass transfer from a companion now present as a white dwarf. An earlier tentative identification of a white dwarf companion to the mild barium star Zeta Cyg is confirmed. For the other stars, no ultraviolet excess attributable to a white dwarf is seen. Limits are set on the bolometric magnitude and age of a possible white dwarf companion. Since the barium stars do not have obvious progenitors among main-sequence and subgiant stars, mass transfer must be presumed to occur when the mass-gaining star is already on the giant branch. This restriction, and the white dwarf's minimum age, which is greater than 8 x 10 to the 8th yr, determined for several stars, effectively eliminates the hypothesis that mass transfer from an asymptotic giant branch star creates a barium star. Speculations are presented on alternative methods of producing a barium star in a binary system.

  20. Hygienic importance of increased barium content in some fresh waters.

    PubMed

    Havlík, B; Hanusová, J; Rálková, J

    1980-01-01

    In surface waters of the mining and processing areas of uranium ore there is an increased content of free and bound barium ions due to the use of barium salts for the treatment of waste and mine waters containing radium. In model experiments with the algae Ankistrodesmus falcatus, Chlorella kessleri and Scenedesmus obliquus, we studied the effect of Ba2+ on the accumulation of 226Ra. It was found that the accumulation of radium by algae is negatively influenced with barium concentrations higher than 1 mg.l-1. The accumulation of barium of organisms of primary production was studied using 133BaCl2. At a barium content in the medium of 4.0, 0.46 and 0.04 mu. l-1, the algae accumulated 30-60% of the added amount of barium during an exposure of 15 days. Biochemical analyses showed that barium is bound to the cellular membrane and to other components of the algal cell that cannot be extracted with water or alcohol. PMID:7462608

  1. Photoluminescence of barium titanate and barium zirconate in multilayer disordered thin films at room temperature.

    PubMed

    Moreira, M L; Gurgel, M F C; Mambrini, G P; Leite, E R; Pizani, P S; Varela, J A; Longo, E

    2008-09-25

    The emission of wide band photoluminescence showed a synergic effect on barium zirconate and barium titanate thin films in alternate multilayer system at room temperature by 488 nm exiting wavelength. The thin films obtained by spin-coating were annealed at 350, 450, and 550 degrees C for 2 h. The X-ray patterns revealed the complete separation among the BaTiO3 and BaZrO3 phases in the adjacent films. Visible and intense photoluminescence was governed by BaZrO3 thin films in the multilayer system. Quantum mechanics calculations were used in order to simulate ordered and disordered thin films structures. The disordered models, which were built by using the displacement of formers and modifier networks, showed a different symmetry in each system, which is in accordance with experimental photoluminescence emission, thus allowing to establish a correlation among the structural and optical properties of these multilayered systems. PMID:18593105

  2. Proton conductivity of potassium doped barium zirconates

    SciTech Connect

    Xu Xiaoxiang; Tao Shanwen; Irvine, John T.S.

    2010-01-15

    Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10%. Introducing extra potassium leads to the formation of second phase or YSZ impurities. The water uptake of barium zirconates was increased even with 5% doping of potassium at the A-site. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. The maximum solubility for yttrium at B-sites is around 15 at% after introducing 1 wt% zinc. The conductivity of Ba{sub 0.95}K{sub 0.05}Zr{sub 0.85}Y{sub 0.11}Zn{sub 0.04}O{sub 3-{delta}} at 600 deg. C is 2.2x10{sup -3} S/cm in wet 5% H{sub 2}. The activation energies for bulk and grain boundary are 0.29(2), 0.79(2) eV in wet 5% H{sub 2} and 0.31(1), 0.74(3) eV in dry 5% H{sub 2}. A power density of 7.7 mW/cm{sup 2} at 718 deg. C was observed when a 1 mm thick Ba{sub 0.95}K{sub 0.05}Zr{sub 0.85}Y{sub 0.11}Zn{sub 0.04}O{sub 3-{delta}} pellet was used as electrolyte and platinum electrodes. - Graphical abstract: Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10 %. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. Five percent doping of potassium at A-site can double the total conductivity.

  3. Designed microstructures in textured barium hexaferrite

    NASA Astrophysics Data System (ADS)

    Hovis, David Brian

    It is a fundamental principle of materials science that the microstructure of a material defines its properties and ultimately its performance for a given application. A prime example of this can be found in the large conch shell Strombus gigas, which has an intricate microstructure extending across five distinct length scales. This microstructure gives extraordinary damage tolerance to the shell. The structure of Strombus gigas cannot be replicated in a modern engineering ceramic with any existing processing technique, so new processing techniques must be developed to apply this structure to a model material. Barium hexaferrite was chosen as a model material to create microstructures reminiscent of Strombus gigas and evaluate its structure-property relations. This work describes novel processing methods to produce textured barium hexaferrite with no coupling between the sample geometry and the texture direction. This technique, combining magnetic field-assisted gelcasting with templated grain growth, also allows multilayer samples to be fabricated with different texture directions in adjacent layers. The effects of adding either B2O3 or excess BaCO 3 on the densification and grain growth of barium hexaferrite was studied. The texture produced using this technique was assessed using orientation imaging microscopy (OIM) at Oak Ridge National Laboratory. These measurements showed peak textures as high as 60 MRD and sharp interfaces between layers cast with different texture directions. The effect of oxygen on the quality of gelcasting is also discussed, and it is shown that with proper mold design, it is possible to gelcast multiple layers with differing texture directions without delamination. Monolithic and multilayer samples were produced and tested in four point bending to measure the strength and work of fracture. Modulus measurements, made with the ultrasonic pulse-echo technique, show clear signs of microcracking in both the isotropic and textured samples

  4. Metallurgical Properties and Phase Transformations of Barium-Strontium Modifier

    NASA Astrophysics Data System (ADS)

    Platonov, M. A.; Sulimova, I. S.; Rozhikhina, I. D.; Dmitrienko, V. I.; Horoshun, G. V.

    2016-04-01

    Metallurgical properties and phase transformations of barium-strontium modifier were tested in laboratory conditions resembling steel processing in furnace and ladle. When heating barium-strontium modifier start of melting, kinetics of decomposition, phase and structure transformation were studied. The concentrate under consideration has been revealed to be a complex mineral compound containing barytocalcite, calcite, calciostrontianite, dolomite and siderite. The reaction kinetics of decomposing mineral components of barium-strontium modifier to oxides does not considerably affect slag formation in conditions of out-of-furnace steel processing.

  5. A high-altitude barium radial injection experiment

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hallinan, T. J.; Deehr, C. S.; Romick, G. J.; Olson, J. V.; Roederer, J. G.; Sydora, R.

    1980-01-01

    A rocket launched from Poker Flat, Alaska, carried a new type of high-explosive barium shaped charge to 571 km, where detonation injected a thin disk of barium vapor with high velocity nearly perpendicular to the magnetic field. The TV images of the injection are spectacular, revealing three major regimes of expanding plasma which showed early instabilities in the neutral gas. The most unusual effect of the injection is a peculiar rayed barium-ion structure lying in the injection plane and centered on a 5 km 'black hole' surrounding the injection point. Preliminary electrostatic computer simulations show a similar rayed development.

  6. Barium hexaferrite ferrofluids - preparation and physical properties

    NASA Astrophysics Data System (ADS)

    Müller, R.; Hiergeist, R.; Steinmetz, H.; Ayoub, N.; Fujisaki, M.; Schüppel, W.

    1999-07-01

    Barium hexaferrite BaFe 12-2 xTi xCo xO 19 ferrofluids have been prepared for the first time using oleic acid as surfactant and Isopar M ® as carrier liquid. The initial susceptibility versus temperature for zero-field cooling of the ferrofluid was obtained by a vibrating sample magnetometer. TEM pictures of the fluid show isolated particles and only small agglomerates and a mean particle diameter of approx. 8 nm. Numerical calculations of the magneto-viscous effect, based on the local-equilibrium magnetic state model, clearly show the benefit for Ba-ferrite ferrofluids resulting from the high uniaxial anisotropy compared to magnetite ferrofluids. Rheological measurements were performed with a rotational-type viscometer with magnetic field perpendicular to the hydrodynamic vortex axis.

  7. Contrast lipocryolysis

    PubMed Central

    Pinto, Hernán; Melamed, Graciela

    2014-01-01

    Alternative crystal structures are possible for all lipids and each different crystal structure is called a polymorphic form. Inter-conversion between polymorphisms would imply the possibility of leaning crystal formation toward the most effective polymorphism for adipocyte destruction. Food industry has been tempering lipids for decades. Tempering technology applied to lipocryolysis gave birth to “contrast lipocryolysis”, which involves pre- and post-lipocryolysis fat layer heating as part of a specific tempering protocol. In this study, we evaluated the skinfold thickness of 10 subjects after a single contrast lipocryolysis session and witnessed important and fast reductions. PMID:25068088

  8. Phased surgical treatment of barium enema-induced rectal injury and retention of barium in the pelvic floor space

    PubMed Central

    Yang, Xuefei; Xia, Ligang; Huang, Jun; Wang, Jianping

    2014-01-01

    Iatrogenic injuries caused by barium enema are rarely reported. Following a phased surgical protocol for up to one year, we have successfully treated a patient with rectal injury and severe infection of the pelvic floor space complicated with retention of large amounts of barium and vaginal fistula. In this article, the phased surgery planning for the treatment of rectal injury complicated with vaginal fistula is discussed in terms of the pros and cons, and the observed effect and evolution of barium retained in the pelvic floor space are described. PMID:25405155

  9. In vivo X-Ray Computed Tomographic Imaging of Soft Tissue with Native, Intravenous, or Oral Contrast

    PubMed Central

    Wathen, Connor A.; Foje, Nathan; van Avermaete, Tony; Miramontes, Bernadette; Chapaman, Sarah E.; Sasser, Todd A.; Kannan, Raghuraman; Gerstler, Steven; Leevy, W. Matthew

    2013-01-01

    X-ray Computed Tomography (CT) is one of the most commonly utilized anatomical imaging modalities for both research and clinical purposes. CT combines high-resolution, three-dimensional data with relatively fast acquisition to provide a solid platform for non-invasive human or specimen imaging. The primary limitation of CT is its inability to distinguish many soft tissues based on native contrast. While bone has high contrast within a CT image due to its material density from calcium phosphate, soft tissue is less dense and many are homogenous in density. This presents a challenge in distinguishing one type of soft tissue from another. A couple exceptions include the lungs as well as fat, both of which have unique densities owing to the presence of air or bulk hydrocarbons, respectively. In order to facilitate X-ray CT imaging of other structures, a range of contrast agents have been developed to selectively identify and visualize the anatomical properties of individual tissues. Most agents incorporate atoms like iodine, gold, or barium because of their ability to absorb X-rays, and thus impart contrast to a given organ system. Here we review the strategies available to visualize lung, fat, brain, kidney, liver, spleen, vasculature, gastrointestinal tract, and liver tissues of living mice using either innate contrast, or commercial injectable or ingestible agents with selective perfusion. Further, we demonstrate how each of these approaches will facilitate the non-invasive, longitudinal, in vivo imaging of pre-clinical disease models at each anatomical site. PMID:23711461

  10. Ocean-Atmosphere Environments of Antarctic-Region Cold-Air Mesocyclones: Evaluation of Reanalyses for Contrasting Adjacent 10-Day Periods ("Macro-Weather") in Winter.

    NASA Astrophysics Data System (ADS)

    Carleton, A. M.; Auger, J.; Birkel, S. D.; Maasch, K. A.; Mayewski, P. A.; Claud, C.

    2015-12-01

    Mesoscale cyclones in cold-air outbreaks (mesocyclones) feature in the weather and climate of the Antarctic (e.g., Ross Sea) and sub-antarctic (Drake Passage). They adversely impact field operations, and influence snowfall, the ice-sheet mass balance, and sea-air energy fluxes. Although individual mesocyclones are poorly represented on reanalyses, these datasets robustly depict the upper-ocean and troposphere environments in which multiple mesocyclones typically form. A spatial metric of mesocyclone activity—the Meso-Cyclogenesis Potential (MCP)—used ERA-40 anomaly fields of: sea surface temperature (SST) minus marine air temperature (MAT), near-surface winds, 500 hPa air temperature, and the sea-ice edge location. MCP maps composited by teleconnection phases for 1979-2001, broadly correspond to short-period satellite "climatologies" of mesocyclones. Here, we assess 3 reanalysis datasets (CFSR, ERA-I and MERRA) for their reliably to depict MCP patterns on weekly to sub-monthly periods marked by strong regional shifts in mesocyclone activity (frequencies, track densities) occurring during a La Niña winter: June 21-30, 1999 (SE Indian Ocean) and September 1-10, 1999 (Ross Sea sector). All reanalyses depict the marked variations in upper ocean and atmosphere variables between adjacent 10-day periods. Slight differences may owe to model resolution or internal components (land surface, coupled ocean models), and/or how the observations are assimilated. For June 21-30, positive SST-MAT, southerly winds, proximity to the ice edge, and negative T500, accompany increased meso-cyclogenesis. However, for September 1-10, surface forcing does not explain frequent comma cloud "polar lows" north-east of the Ross Sea. Inclusion of the upper-level diffluence (e.g., from Z300 field) in the MCP metric, better depicts the observed mesocyclone activity. MCP patterns on these "macro-weather" time scales appear relatively insensitive to the choice of reanalysis.

  11. Upper gastrointestinal barium evaluation of duodenal pathology: A pictorial review

    PubMed Central

    Gupta, Pankaj; Debi, Uma; Sinha, Saroj Kant; Prasad, Kaushal Kishor

    2014-01-01

    Like other parts of the gastrointestinal tract (GIT), duodenum is subject to a variety of lesions both congenital and acquired. However, unlike other parts of the GIT viz. esophagus, rest of the small intestine and large intestine, barium evaluation of duodenal lesions is technically more challenging and hence not frequently reported. With significant advances in computed tomography technology, a thorough evaluation including intraluminal, mural and extramural is feasible in a single non-invasive examination. Notwithstanding, barium evaluation still remains the initial and sometimes the only imaging study in several parts of the world. Hence, a thorough acquaintance with the morphology of various duodenal lesions on upper gastrointestinal barium examination is essential in guiding further evaluation. We reviewed our experience with various common and uncommon barium findings in duodenal abnormalities. PMID:25170399

  12. Calculated emission rates for barium releases in space

    NASA Technical Reports Server (NTRS)

    Stenbaek-Nielsen, H. C.

    1989-01-01

    The optical emissions from barium releases in space are caused by resonance and fluorescent scattering of sunlight. Emission rates for the dominant ion and neutral lines are calculated assuming the release to be optically thin and the barium to be in radiative equilibrium with the solar radiation. The solar spectrum has deep Fraunhofer absorption lines at the primary barium ion resonances. A velocity component toward or away from the sun will Doppler shift the emission lines relative to the absorption lines and the emission rates will increase many-fold over the rest value. The Doppler brightening is important in shaped charge or satellite releases where the barium is injected at high velocities. Emission rates as a function of velocity are calculated for the 4554, 4934, 5854, 6142 and 6497 A ion emission lines and the dominant neutral line at 5535 A. Results are presented for injection parallel to the ambient magnetic field, B, and for injection at an angle to B.

  13. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1983-01-01

    The feasibility of making non-volatile digital memory devices of barium titanate, BaTiO3, that are integrated onto a silicon substrate with the required ferroelectric film produced by processing, compatible with silicon technology was examined.

  14. Synthesis, photoluminescence and magnetic properties of barium vanadate nanoflowers

    SciTech Connect

    Xu, Jing; Hu, Chenguo; Xi, Yi; Peng, Chen; Wan, Buyong; He, Xiaoshan

    2011-06-15

    Graphical abstract: The flower-shaped barium vanadate was obtained for the first time. The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. Research highlights: {yields} In the paper, the flower-shaped barium vanadate were obtained for the first time. The CHM method used here is new and simple for preparation of barium vanadate. {yields} The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. {yields} The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g. {yields} The mechanisms of PL and magnetic property of barium vanadate nanoflowers have been discussed. -- Abstract: The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V{sub 2}O{sub 5} and BaCl{sub 2} at 200 {sup o}C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba{sub 3}V{sub 2}O{sub 8} with small amount of Ba{sub 3}VO{sub 4.8} coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of {approx}20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO{sub 4} tetrahedron with T{sub d} symmetry in Ba{sub 3}V{sub 2}O{sub 8}. The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g, which is mainly due to the presence of a non

  15. A Mechanistic Study of Nanoscale Structure Development, Phase Transition, Morphology Evolution, and Growth of Ultrathin Barium Titanate Nanostructured Films

    NASA Astrophysics Data System (ADS)

    Ashiri, Rouholah

    2014-08-01

    In the present work, an improved method is developed for preparing highly pure ultrathin barium titanate nanostructured films with desired structural and morphological characteristics. In contrast to other approaches, our method can be carried out at a relatively lower temperature to obtain barium titanate ultrathin films free from secondary phases, impurities, and cracks. To reach an in-depth understanding of scientific basis of the proposed process, and in order to disclose the mechanism of formation and growth of barium titanate ultrathin film, in-detail analysis is carried out using XRD, SEM, FE-SEM, and AFM techniques aided by theoretical calculations. The effects of calcining temperature on the nanoscale structure development, phase transition, morphology evolution, and growth mechanism of the ultrathin barium titanate nanostructured films are studied. XRD results indicate that the reaction leading to the formation of the barium titanate initiates at about 873 K (600 °C) and completes at about 1073 K (800 °C). Moreover, secondary phases are not detected in the XRD patterns of the ultrathin films which this observation ensures the phase purity of the ultrathin films. The results show that the ultrathin films are nanothickness and nanostructured leading to the enhancement of rate of diffusion by activating short-circuit diffusion mechanisms. The high rate of the diffusion enhances the rate of the formation of barium titanate and also prevents from the formation of the secondary phases in the final products. SEM and AFM results indicate that the deposited ultrathin films are crack-free exhibiting a dense nanogranular structure. The results indicate that the root-mean square (RMS) roughness of the ultrathin films is in the range of 1.66 to 6.71 nm indicating the surface of the ultrathin films is smooth. RMS roughness also increases with an increase in the calcining temperature which this observation seems to be related to the grain growth process. Finally

  16. A search for technetium (Tc II) in barium stars

    NASA Technical Reports Server (NTRS)

    Little-Marenin, Irene R.; Little, Stephen J.

    1987-01-01

    The authors searched without success for the lines of Tc II at 2647.02, 2610.00 and 2543.24 A in IUE spectra of the barium stars HR 5058, Omicron Vir, and Zeta Cap. The lack of Tc II implies that the observed s-process enhancements were produced more than half a million years ago and supports the suggestion that the spectral peculiarities of barium stars are probably related to the binary nature of the stars.

  17. 'Skidding' of the CRRES G-9 barium release

    NASA Technical Reports Server (NTRS)

    Huba, J. D.; Mitchell, H. G.; Fedder, J. A.; Bernhardt, P. A.

    1992-01-01

    A simulation study and experimental data of the CRRES G-9 ionospheric barium release are presented. The simulation study is based on a 2D electrostatic code that incorporates time-dependent coupling to the background plasma. It is shown that the densest portion of the barium ion cloud 'skids' about 15 km within the first three seconds following the release, consistent with the optical data analyses.

  18. Contrast agent comparison for three-dimensional micro-CT angiography: A cadaveric study.

    PubMed

    Kingston, Mitchell J; Perriman, Diana M; Neeman, Teresa; Smith, Paul N; Webb, Alexandra L

    2016-07-01

    Barium sulfate and lead oxide contrast media are frequently used for cadaver-based angiography studies. These contrast media have not previously been compared to determine which is optimal for the visualisation and measurement of blood vessels. In this study, the lower limb vessels of 16 embalmed Wistar rats, and four sets of cannulae of known diameter, were injected with one of three different contrast agents (barium sulfate and resin, barium sulfate and gelatin, and lead oxide combined with milk powder). All were then scanned using micro-computed tomography (CT) angiography and 3-D reconstructions generated. The number of branching generations of the rat lower limb vessels were counted and compared between the contrast agents using ANOVA. The diameter of the contrast-filled cannulae, were measured and used to calculate the accuracy of the measurements by comparing the bias and variance of the estimates. Intra- and inter-observer reliability were calculated using intra-class correlation coefficients. There was no significant difference (mean difference [MD] 0.05; MD 95% confidence interval [CI] -0.83 to 0.93) between the number of branching generations for barium sulfate-resin and lead oxide-milk powder. Barium sulfate-resin demonstrated less bias and less variance of the estimates (MD 0.03; standard deviation [SD] 1.96 mm) compared to lead oxide-milk powder (MD 0.11; SD 1.96 mm) for measurements of contrast-filled cannulae scanned at high resolution. Barium sulfate-resin proved to be more accurate than lead oxide-milk powder for high resolution micro-CT scans and is preferred due to its non-toxicity. This technique could be applied to any embalmed specimen model. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27075920

  19. Chemical compositions responsible for inflammation and tissue damage in the mouse lung by coarse and fine particulate samples from contrasting air pollution in Europe.

    PubMed

    Happo, Mikko S; Hirvonen, Maija-Riitta; Halinen, Arja I; Jalava, Pasi I; Pennanen, Arto S; Sillanpaa, Markus; Hillamo, Risto; Salonen, Raimo O

    2008-11-01

    Inflammation is regarded as an important mechanism in mortality and morbidity associated with exposures of cardiorespiratory patients to urban air particulate matter. We investigated the association of the chemical composition and sources of urban air fine (PM(2.5-0.2)) and coarse (PM(10-2.5)) particulate samples with the inflammatory activity in the mouse lung. The particulate samples were collected during selected seasons in six European cities using a high-volume cascade impactor. Healthy C57BL/6J mice were intratracheally instilled with a single dose (10 mg/kg) of the particulate samples. At 4, 12, and 24 h after the exposure, the lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: cell number, total protein, and cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6, and KC). Dicarboxylic acids and transition metals, especially Ni and V, in PM(2.5-0.2) correlated positively and some secondary inorganic ions (NO3(-), NH4(+)) negatively with the inflammatory activity. Total organic matter and SO4(2-) had no consistent correlations. In addition, the soil-derived constituents (Ca2+, Al, Fe, Si) showed positive correlations with the PM(2.5-0.2)-induced inflammatory activity, but their role in PM(10-2.5) remained obscure, possibly due to largely undefined biogenic material. Markers of poor biomass and coal combustion, i.e., monosaccharide anhydrides and As, were associated with elevated PAH contents in PM(2.5-0.2) and a consistent immunosuppressive effect. Overall, our results support epidemiological findings that the local sources of incomplete combustion and resuspended road dust are important in urban air particulate pollution-related health effects. PMID:18855153

  20. Differences between water permeability of astomatous and stomatous cuticular membranes: effects of air humidity in two species of contrasting drought-resistance strategy

    PubMed Central

    Karbulková, Jana; Schreiber, Lukas; Macek, Petr; Šantrůček, Jiří

    2008-01-01

    Cuticular water permeabilities of adaxial and abaxial leaf surfaces and their dependence on relative air humidity (RH) applied in long-term and short-term regimes have been analysed for Hedera helix, native in a temperate climate, and Zamioculcas zamiifolia, native in subtropical regions. The water permeability of cuticular membranes (CM) isolated from the adaxial (astomatous) and abaxial (stomatous) leaf sides was measured using a method which allowed the separation of water diffusion through the remnants of the original stomatal pores from water diffusion through the solid cuticle. The long-term effects of low (20–40%) or high (60–80%) RH applied during plant growth and leaf ontogeny (‘growth RH’) and the short-term effects of applying 2% or 100% RH while measuring permeability (‘measurement RH’) were investigated. With both species, water permeability of the solid stomatous CM was significantly higher than the permeability of the astomatous CM. Adaxial cuticles of plants grown in humid air were more permeable to water than those from dry air. The adaxial CM of the drought-tolerant H. helix was more permeable and more sensitive to growth RH than the adaxial CM of Z. zamiifolia, a species avoiding water stress. However, permeability of the solid abaxial CM was similar in both species and independent of growth RH. The lack of a humidity response in the abaxial CM is attributed to a higher degree of cuticular hydration resulting from stomatal transpiration. The ecophysiological significance of higher permeability of the solid stomatous CM compared to the astomatous CM is discussed. PMID:18836141

  1. Chemical compositions responsible for inflammation and tissue damage in the mouse lung by coarse and fine particulate samples from contrasting air pollution in Europe

    SciTech Connect

    Happo, M.S.; Hirvonen, M.R.; Halinen, A.I.; Jalava, P.I.; Pennanen, A.S.; Sillanpaa, M.; Hillamo, R.; Salonen, R.O.

    2008-07-01

    Inflammation is regarded as an important mechanism in mortality and morbidity associated with exposures of cardiorespiratory patients to urban air particulate matter. We investigated the association of the chemical composition and sources of urban air fine (PM2.5-0.2) and coarse (PM10-2.5) particulate samples with the inflammatory activity in the mouse lung. The particulate samples were collected during selected seasons in six European cities using a high-volume cascade impactor. Healthy C57BL/6J mice were intratracheally instilled with a single dose (10 mg/kg) of the particulate samples. At 4, 12, and 24 h after the exposure, the lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: cell number, total protein, and cytokines (tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and KC). Dicarboxylic acids and transition metals, especially Ni and V, in PM2.5-0.2 correlated positively and some secondary inorganic ions (NO{sub 3}{sup -}, NH{sub 4}{sup +}) negatively with the inflammatory activity. Total organic matter and SO{sub 4}{sup 2-} had no consistent correlations. In addition, the soil-derived constituents (Ca{sup 2+}, Al, Fe, Si) showed positive correlations with the PM2.5-0.2-induced inflammatory activity, but their role in PM10 (2.5) remained obscure, possibly due to largely undefined biogenic material. Markers of poor biomass and coal combustion, i.e., monosaccharide anhydrides and As, were associated with elevated PAH contents in PM2.5 (0.2) and a consistent immunosuppressive effect. Overall, our results support epidemiological findings that the local sources of incomplete combustion and resuspended road dust are important in urban air particulate pollution-related health effects.

  2. Effect of B-site europium doping on the hydrogen transport properties of barium cerate

    NASA Astrophysics Data System (ADS)

    Rhodes, James Michael

    Barium cerate doped with europium on the Ce-site (B-site of the ABO3 perovskite structure) has been investigated as a potential material for hydrogen separation. Barium cerate doped with 15 mol% europium (BaCe0.85Eu0.15O3-delta) demonstrated higher electrical conductivity in a hydrogen-containing gas stream than gadolinium-doped barium cerate (BaCe0.85Gd0.15O3-delta), which was known to have one of the highest conductivities (0.027 S/cm 2 compared to 0.021 S/cm2 at 800°C). For europium dopant levels between 5 to 25 mol%, the sample doped with 15 mol% demonstrated higher electrical conductivities in dry forming gas (4% H2/96% N2) dry air, and wet nitrogen. The activation energies in dry air (˜0.60 eV) were indicative of p-type electronic conduction, and the activation energies in hydrogen-containing gases (˜0.35--0.45 eV) were indicative of protonic conduction. With BaCe0.85Eu0.15O3-delta , the onset of n-type electronic conductivity necessary for hydrogen separation was shown to occur at ˜600°C. A gas-tight glass seal was developed to study the hydrogen permeation properties of BaCe0.85Eu0.15O3-delta. The glass seal was a composite of a glass containing strontium oxide, boron oxide, silicon oxide, aluminum oxide, and lanthanum oxide mixed with doped barium cerate powder. The seal would form at temperatures >875°C, allowing for testing down to 650°C. The effect of temperature, feed-side hydrogen partial pressure, and membrane thickness on hydrogen permeation flux of BaCe0.85Eu0.15O 3-delta was investigated. For the range of thicknesses studied (0.75 to 2.00 mm), the performance of BaCe0.85Eu0.15O 3-delta membranes is under mixed control of bulk diffusion and surface kinetics. This mixed control indicates that investigating BaCe 0.85Eu0.15O3-delta membranes thinner than 0.75 mm would result in a limited increase in hydrogen permeation flux unless measures were taken to improve surface kinetics. The need for improved surface kinetics was confirmed when surface

  3. Coherent control of photoionization of atomic barium

    NASA Astrophysics Data System (ADS)

    Yamazaki, Rekishu

    We present the results of our study on coherent control of photoionization of atomic barium. Our study focused on the understanding of the controllability, especially due to the effect of the coherent interaction between the atomic system and the laser field. The first half of the study investigates the mechanisms of the control behind the previously observed laser phase-insensitive product state control. The controllability of this excitation scheme, two-color two-photon resonantly enhanced excitation, was analyzed from two aspects, the role of ac Stark shift introduced by the strong laser field and the multi-pathway quantum mechanical interferences. We have analyzed the excitation scheme from the analysis of the photoelectron angular distribution measured using the excitation scheme and the monitoring of the intermediate state population. Analysis of the data as well as the numerical simulation showed clear understanding of the role of two mechanisms in the product state control reported. We also investigated the control of the phase lag during the product state control. We conducted the control of the phase lag in the study of asymmetric photoelectron angular distribution, which arises from the concurrent even-odd parity outgoing electron wave excitation. The phase lag was controlled in full range, 2pi, and the results were analyzed in terms of the role of autoionizing resonance structures as well as the nature of outgoing electron waves at different locations of the autoionizing resonances.

  4. Barium Tagging for nEXO

    NASA Astrophysics Data System (ADS)

    Fudenberg, Daniel; Brunner, Thomas; Varentsov, Victor; Devoe, Ralph; Dilling, Jens; Gratta, Giorgio; nEXO Collaboration

    2015-10-01

    nEXO is a next-generation experiment designed to search for 0 νββ -decay of Xe-136 in a liquid xenon time projection chamber. Positive observation of this decay would determine the neutrino to be a Majorana particle In order to greatly reduce background contributions to this search, the collaboration is developing several ``barium tagging'' techniques to recover and identify the decay daughter, Ba-136. ``Tagging'' may be available for a 2nd phase of nEXO and will push the sensitivity beyond the inverted neutrino-mass hierarchy. Tagging methods in testing for this phase include Ba-ion capture on a probe with identification by resonance ionization laser spectroscopy, and Ba capture in solid xenon on a cold probe with identification by fluorescence. In addition, Ba tagging for a gas-phase detector, appropriate for a later stage, is being tested. Here efficient ion extraction from heavy carrier gases is key. Detailed gas-dynamic and ion transport calculations have been performed to optimize for ion extraction. An apparatus to extract Ba ions from up to 10 bar xenon gas into vacuum using an RF-only funnel has been constructed and demonstrates extraction of ions from noble gases. We will present this system's status along with results of this R&D program.

  5. High H- ionic conductivity in barium hydride

    NASA Astrophysics Data System (ADS)

    Verbraeken, Maarten C.; Cheung, Chaksum; Suard, Emmanuelle; Irvine, John T. S.

    2015-01-01

    With hydrogen being seen as a key renewable energy vector, the search for materials exhibiting fast hydrogen transport becomes ever more important. Not only do hydrogen storage materials require high mobility of hydrogen in the solid state, but the efficiency of electrochemical devices is also largely determined by fast ionic transport. Although the heavy alkaline-earth hydrides are of limited interest for their hydrogen storage potential, owing to low gravimetric densities, their ionic nature may prove useful in new electrochemical applications, especially as an ionically conducting electrolyte material. Here we show that barium hydride shows fast pure ionic transport of hydride ions (H-) in the high-temperature, high-symmetry phase. Although some conductivity studies have been reported on related materials previously, the nature of the charge carriers has not been determined. BaH2 gives rise to hydride ion conductivity of 0.2 S cm-1 at 630 °C. This is an order of magnitude larger than that of state-of-the-art proton-conducting perovskites or oxide ion conductors at this temperature. These results suggest that the alkaline-earth hydrides form an important new family of materials, with potential use in a number of applications, such as separation membranes, electrochemical reactors and so on.

  6. Development of advanced barium ferrite tape media

    NASA Astrophysics Data System (ADS)

    Shimizu, Osamu; Oyanagi, Masahito; Morooka, Atsushi; Mori, Masahiko; Kurihashi, Yuich; Tada, Toshio; Suzuki, Hiroyuki; Harasawa, Takeshi

    2016-02-01

    We developed an advanced particulate magnetic tape using fine barium ferrite (BaFe) particles for magnetic-tape storage systems. The new tape showed a signal-to-noise ratio (SNR) that was 3.5 dB higher than that of the commercially available BaFe tape used for the Linear Tape Open generation 6 tape-storage system, at a linear density of 300 kfci measured with a giant magnetoresistive head with a reader width of 0.45 μm. Such significant increase in SNR was achieved by reducing the magnetic particle volume from 1950 to 1350 nm3, while maintaining a sufficiently high thermal stability, improving the perpendicular squareness ratio from 0.66 to 0.83, and improving the surface roughness from 2.5 to 2.0 nm when measured by atomic force microscopy and from 2.4 to 0.9 nm when measured by optical interferometry. This paper describes the characteristics of the new BaFe particles and media, which are expected to be employed for future high-capacity linear-tape systems.

  7. Reactions of calcium orthosilicate and barium zirconate with oxides and sulfates of various elements

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, I.

    1979-01-01

    Calcium orthosilicate and barium zirconate were evaluated as the insulation layer of thermal barrier coatings for air cooled gas turbine components. Their reactions with various oxides and sulfates were studied at 1100 C and 1300 C for times ranging up to 400 and 200 hours, respectively. These oxides and sulfates represent potential impurities or additives in gas turbine fuels and in turbine combustion air, as well as elements of potential bond coat alloys. The phase compositions of the reaction products were determined by X-ray diffraction analysis. BaZrO3 and 2CaO-SiO2 both reacted with P2O5, V2O5, Cr2O3, Al2O3, and SiO2. In addition, 2CaO-SiO2 reacted with Na2O, BaO, MgO, and CoO and BaZrO3 reacted with Fe2O3.

  8. Synoptic evaluation of carbon cycling in Beaufort Sea during summer: contrasting river inputs, ecosystem metabolism and air-sea CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Forest, A.; Coupel, P.; Else, B.; Nahavandian, S.; Lansard, B.; Raimbault, P.; Papakyriakou, T.; Gratton, Y.; Fortier, L.; Tremblay, J.-É.; Babin, M.

    2013-10-01

    The accelerated decline in Arctic sea ice combined with an ongoing trend toward a more dynamic atmosphere is modifying carbon cycling in the Arctic Ocean. A critical issue is to understand how net community production (NCP; the balance between gross primary production and community respiration) responds to changes and modulates air-sea CO2 fluxes. Using data collected as part of the ArcticNet-Malina 2009 expedition in southeastern Beaufort Sea (Arctic Ocean), we synthesize information on sea ice, wind, river, water column properties, metabolism of the planktonic food web, organic carbon fluxes and pools, as well as air-sea CO2 exchange, with the aim of identifying indices of ecosystem response to environmental changes. Data were analyzed to develop a non-steady-state carbon budget and an assessment of NCP against air-sea CO2 fluxes. The mean atmospheric forcing was a mild upwelling-favorable wind (~5 km h-1) blowing from the N-E and a decaying ice cover (<80% concentration) was observed beyond the shelf, the latter being fully exposed to the atmosphere. We detected some areas where the surface mixed layer was net autotrophic owing to high rates of primary production (PP), but the ecosystem was overall net heterotrophic. The region acted nonetheless as a sink for atmospheric CO2 with a mean uptake rate of -2.0 ± 3.3 mmol C m-2d-1. We attribute this discrepancy to: (1) elevated PP rates (>600 mg C m-2d-1) over the shelf prior to our survey, (2) freshwater dilution by river runoff and ice melt, and (3) the presence of cold surface waters offshore. Only the Mackenzie River delta and localized shelf areas directly affected by upwelling were identified as substantial sources of CO2 to the atmosphere (>10mmol C m-2d-1). Although generally <100 mg C m-2d-1, daily PP rates cumulated to a total PP of ~437.6 × 103 t C, which was roughly twice higher than the organic carbon delivery by river inputs (~241.2 × 103 t C). Subsurface PP represented 37.4% of total PP for the

  9. Preparation of barium hexaferrite powders using oxidized steel scales waste

    NASA Astrophysics Data System (ADS)

    Septiani, Ardita; Idayanti, Novrita; Kristiantoro, Tony

    2016-02-01

    Research on preparation of barium hexaferrite powders has been done using Hot Strip Mill scales as raw materials. Hot Strip Mill scales are oxidized steel scales waste from steel industrial process. The method used for preparing the barium hexaferrite powders was solid state reaction method. Oxidized steel scales were milled using ball mill for 10 hours, then screened through a 250 mesh sieve to obtain powders with maximum size of 63 µm. Powders were roasted at 600°C temperature for 4 hours to obtain hematite (Fe2O3) phase. Roasted powders were then mixed with barium carbonate, and were subsequently milled for 16 hours. After mixing, powders were calcined with an increasing rate of 10°C/min and maintained at 1100°C for 3 hours. Calcination process was performed to acquire barium hexaferrite phase. X-ray Diffraction (XRD) characterization in conjunction with RIR analysis showed that 85 wt. % of barium hexaferrite is formed. The magnetic properties of powders were characterized using Permagraph. It is found the value of remanent induction is 1.09 kG, coercivity of 2.043 kOe, and the maximum energy product of 0.25 MGOe.

  10. Acceleration of barium ions near 8000 km above an aurora

    NASA Technical Reports Server (NTRS)

    Stenbaek-Nielsen, H. C.; Hallinan, T. J.; Wescott, E. M.; Foeppl, H.

    1984-01-01

    A barium shaped charge, named Limerick, was released from a rocket launched from Poker Flat Research Range, Alaska, on March 30, 1982, at 1033 UT. The release took place in a small auroral breakup. The jet of ionized barium reached an altitude of 8100 km 14.5 min after release, indicating that there were no parallel electric fields below this altitude. At 8100 km the jet appeared to stop. Analysis shows that the barium at this altitude was effectively removed from the tip. It is concluded that the barium was actually accelerated upward, resulting in a large decrease in the line-of-sight density and hence the optical intensity. The parallel electric potential in the acceleration region must have been greater than 1 kV over an altitude interval of less than 200 km. The acceleration region, although presumably auroral in origin, did not seem to be related to individual auroral structures, but appeared to be a large-scale horizontal structure. The perpendicular electric field below, as deduced from the drift of the barium, was temporally and spatially very uniform and showed no variation related to individual auroral structures passing through.

  11. Both barium and calcium activate neuronal potassium currents.

    PubMed Central

    Ribera, A B; Spitzer, N C

    1987-01-01

    Amphibian spinal neurons in culture possess both rapidly inactivating and sustained calcium-dependent potassium current components, similar to those described for other cells. Divalent cation-dependent whole-cell outward currents were isolated by subtracting the voltage-dependent potassium currents recorded from Xenopus laevis neurons in the presence of impermeant cadmium (100-500 microM) from the currents produced without cadmium but in the presence of permeant divalent cations (50-100 microM). These concentrations of permeant ions were low enough to avoid contamination by macroscopic inward currents through calcium channels. Calcium-dependent potassium currents were reduced by 1 microM tetraethylammonium. These currents can also be activated by barium or strontium. Barium as well as calcium activated outward currents in young neurons (6-8 hr) and in relatively mature neurons (19-26 hr in vitro). However, barium influx appeared to suppress the sustained voltage-dependent potassium current in most cells. Barium also activated at least one class of potassium channels observed in excised membrane patches, while blocking others. The blocking action may have masked and hindered detection of the stimulatory action of barium in other systems. PMID:2442762

  12. Synoptic evaluation of carbon cycling in the Beaufort Sea during summer: contrasting river inputs, ecosystem metabolism and air-sea CO2 fluxes

    NASA Astrophysics Data System (ADS)

    Forest, A.; Coupel, P.; Else, B.; Nahavandian, S.; Lansard, B.; Raimbault, P.; Papakyriakou, T.; Gratton, Y.; Fortier, L.; Tremblay, J.-É.; Babin, M.

    2014-05-01

    The accelerated decline in Arctic sea ice and an ongoing trend toward more energetic atmospheric and oceanic forcings are modifying carbon cycling in the Arctic Ocean. A critical issue is to understand how net community production (NCP; the balance between gross primary production and community respiration) responds to changes and modulates air-sea CO2 fluxes. Using data collected as part of the ArcticNet-Malina 2009 expedition in the southeastern Beaufort Sea (Arctic Ocean), we synthesize information on sea ice, wind, river, water column properties, metabolism of the planktonic food web, organic carbon fluxes and pools, as well as air-sea CO2 exchange, with the aim of documenting the ecosystem response to environmental changes. Data were analyzed to develop a non-steady-state carbon budget and an assessment of NCP against air-sea CO2 fluxes. During the field campaign, the mean wind field was a mild upwelling-favorable wind (~ 5 km h-1) from the NE. A decaying ice cover (< 80% concentration) was observed beyond the shelf, the latter being fully exposed to the atmosphere. We detected some areas where the surface mixed layer was net autotrophic owing to high rates of primary production (PP), but the ecosystem was overall net heterotrophic. The region acted nonetheless as a sink for atmospheric CO2, with an uptake rate of -2.0 ± 3.3 mmol C m-2 d-1 (mean ± standard deviation associated with spatial variability). We attribute this discrepancy to (1) elevated PP rates (> 600 mg C m-2 d-1) over the shelf prior to our survey, (2) freshwater dilution by river runoff and ice melt, and (3) the presence of cold surface waters offshore. Only the Mackenzie River delta and localized shelf areas directly affected by upwelling were identified as substantial sources of CO2 to the atmosphere (> 10 mmol C m-2 d-1). Daily PP rates were generally < 100 mg C m-2 d-1 and cumulated to a total PP of ~ 437.6 × 103 t C for the region over a 35-day period. This amount was about twice the

  13. Barium Depletion in the NSTAR Discharge Cathode After 30,000 Hours of Operation

    NASA Technical Reports Server (NTRS)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2010-01-01

    Dispenser hollow cathodes rely on a consumable supply of barium released by impregnant materials in the pores of a tungsten matrix to maintain a low work function surface. Examinations of cathode inserts from long duration ion engine tests show deposits of tungsten at the downstream end that appear to block the flow of barium from the interior. In addition, a numerical model of barium transport in the insert plasma indicates that the barium partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant barium-producing reaction, and it was postulated previously that this would suppress barium loss in the upstream part of the insert. New measurements of the depth of barium depletion from a cathode insert operated for 30,352 hours reveal that barium loss is confined to a narrow region near the downstream end, confirming this hypothesis.

  14. Rocket having barium release system to create ion clouds in the upper atmosphere

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.; Stokes, C. S.; Smith, E. W.; Murphy, W. J. (Inventor)

    1974-01-01

    A chemical system for releasing a good yield of free barium atoms and barium ions to create ion clouds in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium is presented.

  15. Barium Levels in Soils and Centella asiatica

    PubMed Central

    Ong, Ghim Hock; Yap, Chee Kong; Mahmood, Maziah; Tan, Soon Guan; Hamzah, Suhaimi

    2013-01-01

    In this study, Centella asiatica and surface soils were collected from 12 sampling sites in Peninsular Malaysia, and the barium (Ba) concentrations were determined. The Ba concentration [μg/g dry weight (dw)] was 63.72 to 382.01 μg/g in soils while in C. asiatica, Ba concentrations ranged from 5.05 to 21.88 μg/g for roots, 3.31 to 11.22 μg/g for leaves and 2.37 to 6.14 μg/g for stems. In C. asiatica, Ba accumulation was found to be the highest in roots followed by leaves and stems. The correlation coefficients (r) of Ba between plants and soils were found to be significantly positively correlated, with the highest correlation being between roots-soils (r=0.922, p<005), followed by leaves-soils (r=0.890, p<005) and stems-soils (r=0.848, p<005). This indicates that these three parts of C. asiatica are good biomonitors of Ba pollution. For the transplantation study, four sites were selected as unpolluted [(Universiti Putra Malaysia (UPM)], semi-polluted (Seri Kembangan and Balakong) and polluted sites (Juru). Based on the transplantation study under experimental field and laboratory conditions, Ba concentrations in C. asiatica were significantly (p<0.05) higher after three weeks of exposure at Seri Kembangan, Balakong and Juru. Thus, these experimental findings confirm that the leaves, stems and roots of C. asiatica can reflect the Ba levels in the soils where this plant is found. Three weeks after back transplantation to clean soils, the Ba levels in C. asiatica were still higher than the initial Ba level even though Ba elimination occurred. In conclusion, the leaves, stems and roots of C. asiatica are good biomonitors of Ba pollution. PMID:24575242

  16. Barium Aspiration in an Infant: A Case Report and Review of Management

    PubMed Central

    Jackson, M.; Kapur, N.; Goyal, V.; Choo, K.; Sarikwal, A.; Masters, I. B.; Isles, Alan F.

    2014-01-01

    We describe a case of bilateral inhalation of barium in an infant following a barium swallow for investigation of dusky spells associated with feeds. A bronchoscopy subsequently revealed the presence of a mid-tracheal tracheo-esophageal cleft. To date, little has been reported on barium aspiration in children and there is no consensus for management. We review the literature on barium aspiration, its consequences, and make recommendations for management. PMID:24818122

  17. Emission spectrographic determination of barium in sea water using a cation exchange concentration procedure

    USGS Publications Warehouse

    Szabo, B. J.; Joensuu, O.

    1967-01-01

    A concentration technique employing Dowex 50W cation exchange resin is described for the determination of barium in sea water. The separated barium is precipitated as fluoride together with calcium and strontium and measured by emission spectrographic analysis. The vertical distribution of barium in sea water has been measured in the Caribbean Sea and the Atlantic Ocean. The barium content varied between 7 and 23 ??g. per liter; in two profiles, the lowest concentrations were at a depth of about 1000 meters.

  18. Prompt ionization in the CRIT II barium releases

    NASA Astrophysics Data System (ADS)

    Torbert, R. B.; Kletzing, C. A.; Liou, K.; Rau, D.

    1992-05-01

    Observations of electron and ion distributions inside a fast neutral barium jet in the ionosphere show significant fluxes within 4 km of release, presumably related to beam plasma instability processes involved in the Critical Ionization Velocity (CIV) effect. Electron fluxes exceeding 5 x 10 exp 12/sq cm-str-sec-keV were responsible for ionizing both the streaming barium and ambient oxygen. Resulting ion fluxes seem to be consistent with 1-2 percent ionization of the fast barium, as reported by optical observations, although the extended spatial distribution of the optically observed ions is difficult to reconcile with the in situ observations. When the perpendicular velocity of the neutrals falls below critical values, these processes shut off. Although these observations resemble the earlier Porcupine experimental results (Haerendel, 1982), theoretical understanding of the differences between these data and that of earlier negative experiments is still lacking.

  19. White dwarf kicks and implications for barium stars

    NASA Astrophysics Data System (ADS)

    Izzard, R. G.; Church, R. P.; Dermine, T.

    The barium stars have caused much grief in the field of binary stellar evolution. They are often eccentric when they should be circular and are not found to have periods longer than 104 days even though wind accretion should still be efficient at such separations. We address both these problems by introducing a kick to white dwarfs when they are born, thus solving the eccentricity problem, and imposing strong orbital angular momentum loss to shrink barium-star binaries down to the observed periods. Whilst our angular momentum prescription is hard to justify for the barium stars it shows that strong angular momentum loss is necessary to reproduce the observed period-eccentricity distribution. We are investigating whether this can be obtained from a circumbinary disc.

  20. Barium-borate-flyash glasses: As radiation shielding materials

    NASA Astrophysics Data System (ADS)

    Singh, Sukhpal; Kumar, Ashok; Singh, Devinder; Thind, Kulwant Singh; Mudahar, Gurmel S.

    2008-01-01

    The attenuation coefficients of barium-borate-flyash glasses have been measured for γ-ray photon energies of 356, 662, 1173 and 1332 keV using narrow beam transmission geometry. The photon beam was highly collimated and overall scatter acceptance angle was less than 3°. Our results have an uncertainty of less than 3%. These coefficients were then used to obtain the values of mean free path (mfp), effective atomic number and electron density. Good agreements have been observed between experimental and theoretical values of these parameters. From the studies of the obtained results it is reported here that from the shielding point of view the barium-borate-flyash glasses are better shields to γ-radiations in comparison to the standard radiation shielding concretes and also to the ordinary barium-borate glasses.

  1. Effect of barium and nickel on the growth of anacystis nidulans

    SciTech Connect

    Lustigman, L.H.L.B.

    1996-12-31

    Anacystis nidulans is a simple, unicellular, prokaryotic microorganism. Like other cyanobacteria it is an obligate photoautotroph that is similar to gram-negative bacteria in cell wall structure, replication, and ability to harbor plasmids. Cyanobacteria are excellent organisms to serve as models for the investigation of a wide variety of biological problems, including indicators of environmental pollution. There have been several studies on the effects of heavy metals on A. nidulans. Toxic metals are a major water pollution problem. Metals come from natural weathering processes of the earth`s crust, but industrialization and urbanization have led to an increase in contamination of aquatic environments, mainly from industrial discharge, pest or disease control agents applied to plants, urban run-off, mining, soil erosion, sewage effluents, air pollution fallout, and other sources. Among these contaminants are nickel, barium, and their derivatives. This study examined the effects of selected concentrations of nickel chloride and barium chloride on the growth of A. nidulans, with and without the addition of EDTA. 19 refs., 3 figs.

  2. Curie temperature and magnetic properties of aluminum doped barium ferrite particles prepared by ball mill method

    NASA Astrophysics Data System (ADS)

    Chen, Daming; Harward, Ian; Baptist, Joshua; Goldman, Sara; Celinski, Zbigniew

    2015-12-01

    Barium ferrite has attracted considerable interest in the fields of permanent magnets and perpendicular magnetic recording due to its strong uniaxial anisotropy and high Curie temperature (Tc). We prepared aluminum doped barium ferrite ceramics (BaAlxFe12-xO19, 0≤x≤6) by the ball mill method. The powder was milled for 96 h, and after forming pellets, annealed for 48 h in air at 1000 °C. The X-ray diffraction (XRD) data show that there are only single hexagonal phases in the samples without any impurity phase. The crystal lattice constants, a and c, were calculated by Cohen's method. Both a and c decrease with increasing x, ranging from 0.588 nm and 2.318 nm to 0.573 nm and 2.294 nm, respectively. A Vibrating Sample Magnetometer (VSM) and Superconducting Quantum Interference Device (SQUID) were used to investigate Tc and magnetic properties of BaFe12-xAlxO19. It is found that Tc decreases with increasing x, from 425 °C to 298 °C. It is also found that the saturated magnetization (4πMs) decreases with increasing x, while the coercivity (Hc) increases with the increase in x. The anisotropy field was also determined from the SQUID measurement.

  3. Compact pulse forming line using barium titanate ceramic material.

    PubMed

    Kumar Sharma, Surender; Deb, P; Shukla, R; Prabaharan, T; Shyam, A

    2011-11-01

    Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO(3)) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 Ω load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber. PMID:22129008

  4. Compact pulse forming line using barium titanate ceramic material

    NASA Astrophysics Data System (ADS)

    Kumar Sharma, Surender; Deb, P.; Shukla, R.; Prabaharan, T.; Shyam, A.

    2011-11-01

    Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO3) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 Ω load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber.

  5. The adhesiometer: a simple device to measure adherence of barium sulfate to intestinal mucosa.

    PubMed

    Salomonowitz, E; Frick, M P; Cragg, A H; Lund, G

    1984-04-01

    A simple, inexpensive device assessing barium sulfate adherence to alimentary tract mucosa was tested in an animal study using pigs and dogs. Interaction of gastric, intestinal, and colonic mucosal lining with three different barium preparations was studied. In both pigs and dogs, barium adherence to gastric mucosa was significantly stronger when compared with colonic mucosa. PMID:6608230

  6. 49 CFR 173.182 - Barium azide-50 percent or more water wet.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Barium azide-50 percent or more water wet. 173.182 Section 173.182 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Class 1 and Class 7 § 173.182 Barium azide—50 percent or more water wet. Barium azide—50 percent or...

  7. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  8. 21 CFR 201.304 - Tannic acid and barium enema preparations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 4 2011-04-01 2011-04-01 false Tannic acid and barium enema preparations. 201.304... Tannic acid and barium enema preparations. (a) It has become a widespread practice for tannic acid to be added to barium enemas to improve X-ray pictures. Tannic acid is capable of causing diminished...

  9. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  10. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  11. 49 CFR 173.182 - Barium azide-50 percent or more water wet.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Barium azide-50 percent or more water wet. 173.182 Section 173.182 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Class 1 and Class 7 § 173.182 Barium azide—50 percent or more water wet. Barium azide—50 percent or...

  12. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  13. 49 CFR 173.182 - Barium azide-50 percent or more water wet.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Barium azide-50 percent or more water wet. 173.182 Section 173.182 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Class 1 and Class 7 § 173.182 Barium azide—50 percent or more water wet. Barium azide—50 percent or...

  14. 49 CFR 173.182 - Barium azide-50 percent or more water wet.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Barium azide-50 percent or more water wet. 173.182 Section 173.182 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Class 1 and Class 7 § 173.182 Barium azide—50 percent or more water wet. Barium azide—50 percent or...

  15. 21 CFR 201.304 - Tannic acid and barium enema preparations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 4 2012-04-01 2012-04-01 false Tannic acid and barium enema preparations. 201.304... Tannic acid and barium enema preparations. (a) It has become a widespread practice for tannic acid to be added to barium enemas to improve X-ray pictures. Tannic acid is capable of causing diminished...

  16. 21 CFR 201.304 - Tannic acid and barium enema preparations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Tannic acid and barium enema preparations. 201.304... Tannic acid and barium enema preparations. (a) It has become a widespread practice for tannic acid to be added to barium enemas to improve X-ray pictures. Tannic acid is capable of causing diminished...

  17. 40 CFR 721.10010 - Barium manganese oxide (BaMnO3).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Barium manganese oxide (BaMnO3). 721... Substances § 721.10010 Barium manganese oxide (BaMnO3). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as barium manganese oxide (BaMnO3) (PMN...

  18. 21 CFR 201.304 - Tannic acid and barium enema preparations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 4 2013-04-01 2013-04-01 false Tannic acid and barium enema preparations. 201.304... Tannic acid and barium enema preparations. (a) It has become a widespread practice for tannic acid to be added to barium enemas to improve X-ray pictures. Tannic acid is capable of causing diminished...

  19. 49 CFR 173.182 - Barium azide-50 percent or more water wet.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Barium azide-50 percent or more water wet. 173.182 Section 173.182 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS... Class 1 and Class 7 § 173.182 Barium azide—50 percent or more water wet. Barium azide—50 percent or...

  20. 21 CFR 201.304 - Tannic acid and barium enema preparations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Tannic acid and barium enema preparations. 201.304... Tannic acid and barium enema preparations. (a) It has become a widespread practice for tannic acid to be added to barium enemas to improve X-ray pictures. Tannic acid is capable of causing diminished...

  1. Barium and antimony distributions on the hands of nonshooters.

    PubMed

    Havakost, D G; Peters, C A; Koons, R D

    1990-09-01

    Barium and antimony levels from selected areas of the left and right hands of 269 nonshooters provide a database for interpretation of gunshot residue swab analysis results. The database represents a variety of activities of individuals sampled by collectors throughout the United States. Nonshooting exposure to barium and antimony can generally be distinguished from firearms-associated exposure by considering the relative levels of the elements, location on the hands, and condition of the swabs. Consistent definition of sampling procedures and accurate analytical results make this database applicable for interpretation of data generated by most gunshot residue swab examiners. PMID:2230685

  2. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1981-01-01

    The photoelectric effect in structures consisting of metal deposited barium titanate film silicon is described. A radio frequency sputtering technique is used to deposit ferroelectric barium titantate films on silicon and quartz. Film properties are measured and correlated with the photoelectric effect characteristics of the films. It was found that to obtain good quality pin hole free films, it is necessary to reduce the substrate temperature during the last part of the deposition. The switching ability of the device with internal applied voltage is improved when applied with a ferroelectric memory device.

  3. Methods for producing monodispersed particles of barium titanate

    DOEpatents

    Hu, Zhong-Cheng

    2001-01-01

    The present invention is a low-temperature controlled method for producing high-quality, ultrafine monodispersed nanocrystalline microsphere powders of barium titanate and other pure or composite oxide materials having particles ranging from nanosized to micronsized particles. The method of the subject invention comprises a two-stage process. The first stage produces high quality monodispersed hydrous titania microsphere particles prepared by homogeneous precipitation via dielectric tuning in alcohol-water mixed solutions of inorganic salts. Titanium tetrachloride is used as an inorganic salt precursor material. The second stage converts the pure hydrous titania microsphere particles into crystalline barium titanate microsphere powders via low-temperature, hydrothermal reactions.

  4. Ionization and expansion of barium clouds in the ionosphere

    NASA Technical Reports Server (NTRS)

    Ma, T.-Z.; Schunk, R. W.

    1993-01-01

    A recently envelope 3D model is used here to study the motion of the barium clouds released in the ionosphere, including the ionization stage. The ionization and the expansion of the barium clouds and the interaction between the clouds and the background ions are investigated using three simulations: a cloud without a directional velocity, a cloud with an initial velocity of 5 km/s across the B field, and a cloud with initial velocity components of 2 km/s both along and across the B field.

  5. Ferroelastic domains in lead-free barium zirconate titanate - barium calcium titanate piezoceramics

    NASA Astrophysics Data System (ADS)

    Ehmke, Matthias Claudius

    Piezoelectricity was first discovered by Pierre and Jaque Curie in the year 1880. Nowadays, piezoelectric materials are used in many application such as high voltage generation in gas igniters, actuation in micro-positioning devices, generation and detection of acoustic waves, emitters and receivers for sonar technology, ultrasonic cleaning, ultrasound medical therapy, and micropumps for ink-jet printers. The most commonly used piezoelectric material since the 1950's is the solid solution system lead zirconate titanate (PZT) that offers high piezoelectric performance under a large range of operating conditions. However, the toxicity of lead requires the replacement of PZT. The studied lead-free alternatives are commonly based on potassium sodium niobate (KNN) and bismuth sodium titanate (BNT), and more recently zirconium and calcium substituted barium titanate (BZT-BCT). The BZT-BCT system exhibits large piezoelectric coefficients that can exceed even those of most PZT compositions under certain conditions. Piezoelectricity was first discovered by Pierre and Jaque Curie in the year 1880. Nowadays, piezoelectric materials are used in many application such as high voltage generation in gas igniters, actuation in micro-positioning devices, generation and detection of acoustic waves, emitters and receivers for sonar technology, ultrasonic cleaning, ultrasound medical therapy, and micropumps for ink-jet printers. The most commonly used piezoelectric material since the 1950's is the solid solution system lead zirconate titanate (PZT) that offers high piezoelectric performance under a large range of operating conditions. However, the toxicity of lead requires the replacement of PZT. The studied lead-free alternatives are commonly based on potassium sodium niobate (KNN) and bismuth sodium titanate (BNT), and more recently zirconium and calcium substituted barium titanate (BZT-BCT). The BZT-BCT system exhibits large piezoelectric coefficients that can exceed even those of

  6. A potentially artifact-free oral contrast agent for gastrointestinal MRI.

    PubMed

    Liebig, T; Stoupis, C; Ros, P R; Ballinger, J R; Briggs, R W

    1993-11-01

    The combination of diamagnetic barium sulfate and superparamagnetic iron oxide (SPIO) in one suspension produces a macroscopic cancellation of positive and negative magnetic susceptibility components that can potentially eliminate susceptibility artifacts even with gradient echo pulse sequences. The relaxation properties that make the SPIO suspension a useful negative contrast agent are retained. PMID:8259066

  7. Chemical abundance analysis of 19 barium stars

    NASA Astrophysics Data System (ADS)

    Yang, Guo-Chao; Liang, Yan-Chun; Spite, Monique; Chen, Yu-Qin; Zhao, Gang; Zhang, Bo; Liu, Guo-Qing; Liu, Yu-Juan; Liu, Nian; Deng, Li-Cai; Spite, Francois; Hill, Vanessa; Zhang, Cai-Xia

    2016-01-01

    We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. The chemical abundances of the sample stars were obtained from an LTE, plane-parallel and line-blanketed atmospheric model by inputting the atmospheric parameters (effective temperatures Teff, surface gravities log g, metallicity [Fe/H] and microturbulence velocity ξt) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants as indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their Na, Al, α- and iron-peak elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-capture) process elements relative to the Sun. Their median abundances of [Ba/Fe], [La/Fe] and [Eu/Fe] are 0.54, 0.65 and 0.40, respectively. The Y I and Zr I abundances are lower than Ba, La and Eu, but higher than the α- and iron-peak elements for the strong Ba stars and similar to the iron-peak elements for the mild stars. There exists a positive correlation between Ba intensity and [Ba/Fe]. For the n-capture elements (Y, Zr, Ba, La), there is an anti-correlation between their [X/Fe] and [Fe/H]. We identify nine of our sample stars as strong Ba stars with [Ba/Fe] >0.6 where seven of them have Ba intensity Ba=2-5, one has Ba=1.5 and another one has Ba=1.0. The remaining ten stars are classified as mild Ba stars with 0.17<[Ba/Fe] <0.54.

  8. Radiography and image-intensified fluoroscopy of barium passage through the gastrointestinal tract in six healthy Amazon parrots (Amazona aestiva).

    PubMed

    Vink-Nooteboom, Mariette; Lumeij, J T; Wolvekamp, W T C

    2003-01-01

    Gastrointestinal contrast studies were performed in six clinically healthy blue-fronted Amazon parrots (Amazona aestiva) using radiography and image-intensified fluoroscopy. During examination, the birds were confined in a perspex cage. The quality of the lateral radiographs was adequate for assessment of the contrast medium-filled gastrointestinal tract. Thirty minutes after administration of 20 mL/kg of a 25% barium sulphate suspension directly in the crop, in all birds the ventriculus was totally outlined by barium. After 60 min, the small intestine was filled in five of six birds. After 180 min, the crop was empty in all birds. The barium-outlined ventriculus had differences in shape on radiographs of individual birds and also between birds. The colon and cloaca had further filling after 120 to 300 min. With image-intensified fluoroscopy, gastrointestinal motility was evaluated. Contractions of the crop were seen, and boluses of contrast medium passing through the esophagus toward the proventriculus were easily identified. Proventricular contractions were rarely noted, but ventriculus motility was present and clearly defined. The ventriculus had a mean of 3.7 contraction cycles/min. In the duodenum and small intestine, rapid antegrade and retrograde peristaltic movements in combination with segmental contractions were seen. In the colon, occasionally very slow peristaltic activity, mainly of segmental nature, was present. During the examinations, no defeacation was recorded. Confinement in a small perspex cage provides an adequate and handy radiological set-up for evaluation of gastrointestinal passage and motility in birds, minimizing the influences of stress and anesthesia. PMID:12620049

  9. Synthesis of phase pure praseodymium barium copper iron oxide.

    PubMed

    Konne, Joshua L; Davis, Sean A; Glatzel, Stefan; Hall, Simon R

    2013-06-18

    The control of crystallization of praseodymium barium copper iron oxide, an intermediate temperature solid oxide fuel cell cathode material, has been demonstrated for the first time using a biotemplated sol-gel synthesis technique. The results obtained showed significant improvement in purity, synthesis time, surface area and simplicity over that previously reported. PMID:23660963

  10. Stabilization of arsenic- and barium-rich glass manufacturing waste

    SciTech Connect

    Fuessle, R.W.; Taylor, M.A.

    2000-03-01

    Effective solidification/stabilization (S/S) of arsenic- and barium-containing D004/D005 waste was accomplished by using a binder of cement with 40% class C fly ash and either ferrous sulfate or ferric sulfate as an additive. Addition of iron salts improves arsenic solidification/stabilization (S/S). Barium may be encapsulated within the stabilized matrix as barium sulfate. Recommended mole ratios for iron/arsenic and barium/sulfate are at least 6 and 1.2, respectively. A binder/waste ratio of 0.15 is volume efficient, but the mix design must be carefully controlled to achieve adequate S/S. In practice, the heterogeneity of waste and large-scale mix operations may preclude close control of reagent dosages, so a binder/waste ratio of 0.40 is preferable. Ferrous sulfate additive is preferable for arsenic S/S because it is effective over a wider range of mix designs and over a long-term curing period. Toxicity characteristic leaching procedure results degraded with long curing time for some mix designs with ferric sulfate additive.

  11. Laser selective excitation of a three-level atom - Barium

    NASA Technical Reports Server (NTRS)

    Carlsten, J. L.

    1974-01-01

    Development of a theory describing the selective excitation of a three-level atom with a tunable laser. The effects of number density, line widths, and laser parameters on the final populations of the levels are discussed. An experiment is described in which a tunable dye laser is used to pump large numbers of barium atoms into a definite excited state.

  12. REMOVING BARIUM AND RADIUM THROUGH CALCIUM CATION EXCHANGE

    EPA Science Inventory

    The removal of barium (Ba) and radium (Ra), which are found in many groundwater sources, was achieved in laboratory studies with an ion exchange process. In the studies, a strong acid resin in the calcium form effectively removed Ba(+2) and Ra (+2) to meet standards. The resin wa...

  13. Effects of light exposure on irradiated barium fluoride crystals

    SciTech Connect

    Wuest, C.R.; Mauger, G.J.

    1993-04-20

    Small barium fluoride crystals have been irradiated using cobalt-60 gamma rays under various illumination conditions to establish the effect of photo-bleaching of the radiation-induced color centers. This paper describes results of a few different experiments conducted at LLNL over the past few weeks.

  14. SEPARATION OF BARIUM VALUES FROM URANYL NITRATE SOLUTIONS

    DOEpatents

    Tompkins, E.R.

    1959-02-24

    The separation of radioactive barium values from a uranyl nitrate solution of neutron-irradiated uranium is described. The 10 to 20% uranyl nitrate solution is passed through a flrst column of a cation exchange resin under conditions favoring the adsorption of barium and certain other cations. The loaded resin is first washed with dilute sulfuric acid to remove a portion of the other cations, and then wash with a citric acid solution at pH of 5 to 7 to recover the barium along with a lesser amount of the other cations. The PH of the resulting eluate is adjusted to about 2.3 to 3.5 and diluted prior to passing through a smaller second column of exchange resin. The loaded resin is first washed with a citric acid solution at a pH of 3 to elute undesired cations and then with citric acid solution at a pH of 6 to eluts the barium, which is substantially free of undesired cations.

  15. Dynamics of a barium release in the magnetospheric tail

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Swenson, G. R.; Geller, S. P.; Doolittle, J. H.; Haerendel, G.

    1989-01-01

    The late time behavior of the May 13, 1985 magnetotail barium cloud is examined. The bulk dynamics of the cloud are studied based on triangulated data and data from Fabry-Perot Doppler velocity measurements. The changes in cloud morphology in relation to the in situ measurements made by the Ion Release Module satellite are discussed.

  16. PROPOSED ORAL REFERENCE DOSE (RFD) FOR BARIUM AND COMPOUNDS

    EPA Science Inventory

    The Integrated Risk Information System (IRIS) is a database of EPA's consensus opinion of the human health effects that may result from exposure to various substances found in the environment. A Toxicological Review and IRIS Summary were prepared for barium and compounds in 1998 ...

  17. BARIUM AND RADIUM REMOVAL FROM GROUNDWATER BY ION EXCHANGE

    EPA Science Inventory

    The primary objective of this study was to determine the applicability of weak acid exchange resin in the hydrogen form for removal of hardness, barium and radium from groundwater. Weak acid resin in the hydrogen form eliminates the addition of sodium to drinking water. The capac...

  18. Nonlinear photonic crystal waveguide structures based on barium titanate thin films and their optical properties

    NASA Astrophysics Data System (ADS)

    Liu, Zhifu; Lin, Pao-Tai; Wessels, Bruce W.; Yi, Fei; Ho, Seng-Tiong

    2007-05-01

    Nonlinear photonic crystal waveguide structures were fabricated from barium titanate thin films using nanolithography. A cascaded Bragg reflector using a strip waveguide was designed and analyzed. Both simulation and experimental results show that there is sufficient refractive index contrast to form a stop band by only etching through the Si3N4 strip layer. The band gap of the Bragg reflector can be engineered through control of the Bragg spacing, thickness, and etching depth of the strip layer. The transmission spectrum of the Bragg reflector waveguide was measured over the spectral range of 1500-1580nm. A 27nm wide stop band was obtained for a millimeter long sample. The nonlinear photonic crystal waveguides are potentially suitable as tunable filters, optical switches, and ultrawide bandwidth modulators.

  19. Growth rate controlled barium partitioning in calcite and aragonite

    NASA Astrophysics Data System (ADS)

    Goetschl, Katja Elisabeth; Mavromatis, Vasileios; Baldermann, Andre; Purgstaller, Bettina; Dietzel, Martin

    2016-04-01

    The barium (Ba) content and the Ba/Ca molar ratios in biogenic and abiotic carbonates have been widely used from the scientific community as a geochemical proxy especially in marine and early diagenetic settings. The Ba content of carbonate minerals has been earlier associated to changes in oceanic circulation that may have been caused by upwelling, changes in weathering regimes and river-runoff as well as melt water discharge. The physicochemical controls of Ba ion incorporation in the two most abundant CaCO3 polymorphs found in Earth's surface environments, i.e. calcite and aragonite, have adequately been studied only for calcite. These earlier studies (i.e. [1]) suggest that at increasing growth rate, Ba partitioning in calcite is increasing as well. In contrast, to date the effect of growth rate on the partitioning of Ba in aragonite remains questionable, despite the fact that this mineral phase is the predominant carbonate-forming polymorph in shallow marine environments. To shed light on the mechanisms controlling Ba ion uptake in carbonates in this study we performed steady-state Ba co-precipitation experiments with calcite and aragonite at 25°C. The obtained results for the partitioning of Ba in calcite are in good agreement with those reported earlier by [1], whereas those for aragonite indicate a reduction of Ba partitioning at elevated aragonite growth rates, with the partitioning coefficient value between solid and fluid to be approaching the unity. This finding is good agreement with the formation of a solid solution in the aragonite-witherite system, owing to the isostructural crystallography of the two mineral phases. Moreover, our data set provides new insights that are required for reconstructing the evolution of the Ba content of pristine marine versus diagenetically altered carbonate minerals commonly occurring in marine subfloor settings, as the thermodynamically less stable aragonite will transform to calcite enriched in Ba, whilst affecting

  20. Ultra-low temperature processing of barium tellurate dielectrics

    NASA Astrophysics Data System (ADS)

    Kwon, Do-Kyun

    Ceramics, metals and polymers have unique electrical properties that are combined for electronic devices and systems. It necessitates lower processing temperatures for ceramics to be compatible with metal and polymer systems. In this thesis, the synthesis, crystal structure, and dielectric properties of barium tellurate are studied for temperatures between 500 and 900°C. Barium tellurate dielectric ceramics (BaTe4O9, BaTe 2O5, BaTe2O6, BaTeO3, BaTeO 4, and Ba2TeO5) are extensively investigated as new LTCC (Low-Temperature Cofired Ceramics) dielectric systems integrated with low resistivity metal electrodes such as silver and aluminum for microwave application. Studies on the phase formation and crystal structure through thermal analyses (Differential Scanning Calorimetry and Thermogravimetric Analysis, DSC-TGA) and X-ray diffraction phase analysis attest that barium tellurates are formed in the temperature range of 500 ˜ 900°C, through the sequential phase formations from Te-rich to Ba-rich phases. The oxygen coordination of the tellurium ion progresses from TeO4 to TeO6 via TeO 3+1 and TeO3 with increasing barium content as confirmed by structural analysis using infrared spectroscopy. High density barium tellurate ceramics are achieved at temperatures as low as 550°C, which provides the potential to be co-fired with low-melting aluminum metal electrodes in LTCC processing. Dielectric permittivity, loss, and temperature stability of barium tellurate dielectric ceramics were measured from 100 Hz to 13 GHz. Barium tellurate ceramics exhibit excellent microwave dielectric properties with intermediate dielectric permittivities and high quality factors (Q). The dielectric properties at microwave frequencies are epsilonr = 17.5, Qxf = 54700 GHz, TCf = -90 ppm/°C for BaTe4O9, epsilonr = 21, Qxf = 50300 GHz, TCf = -51 ppm/°C for BaTe2O6, epsilonr = 10, Qxf = 34000 GHz, TCf = -54 ppm/°C for BaTeO3, and epsilonr = 17, Qx f = 49600 GHz, TCf = -124 ppm/°C for Ba 2TeO5

  1. Preliminary study of the CRRES magnetospheric barium releases

    NASA Technical Reports Server (NTRS)

    Huba, J. D.; Bernhardt, P. A.; Lyon, J. G.

    1992-01-01

    Preliminary theoretical and computational analyses of the Combined Release and Radiation Effects Satellite (CRRES) magnetospheric barium releases are presented. The focus of the studies is on the evolution of the diamagnetic cavity which is formed by the barium ions as they expand outward, and on the structuring of the density and magnetic field during the expansion phase of the releases. Two sets of simulation studies are discussed. The first set is based upon a 2D ideal MHD code and provides estimates of the time and length scales associated with the formation and collapse of the diamagnetic cavity. The second set uses a nonideal MHD code; specifically, the Hall term is included. This additional term is critical to the dynamics of sub-Alfvenic plasma expansions, such as the CRRES barium releases, because it leads to instability of the expanding plasma. Detailed simulations of the G4 and G10 releases were performed. In both cases the expanding plasma rapidly structured: the G4 release structured at time t less than about 3 s and developed scale sizes of about 1-2 km, while the G10 release structured at time t less than about 22 s and developed scale sizes of about 10-15 km. It is also found that the diamagnetic cavity size is reduced from those obtained from the ideal MHD results because of the structure. On the other hand, the structuring allows the formation of plasma blobs which appear to free stream across the magnetic field; thus, the barium plasma can propagate to larger distances traverse to the magnetic field than the case where no structuring occurs. Finally, a new normal mode of the system was discovered which may be excited at the leading edge of the expanding barium plasma.

  2. Design, testing, fabrication and launch support of a liquid chemical barium release payload (utilizing the liquid fluorine-barium salt/hydrazine system)

    NASA Technical Reports Server (NTRS)

    Stokes, C. S.; Smith, E. W.; Murphy, W. J.

    1972-01-01

    A payload was designed which included a cryogenic oxidizer tank, a fuel tank, and burner section. Release of 30 lb of chemicals was planned to occur in 2 seconds at the optimum oxidizer to fuel ratio. The chemicals consisted of 17 lb of liquid fluorine oxidizer and 13 lb of hydrazine-barium salt fuel mixture. The fuel mixture was 17% barium chloride, 16% barium nitrate, and 67% hydrazine, and contained 2.6 lb of available barium. Two significant problem areas were resolved during the program: explosive valve development and burner operation. The release payload was flight tested, from Wallops Island, Virginia. The release took place at an altitude of approximately 260 km. The release produced a luminous cloud which expanded very rapidly, disappearing to the human eye in about 20 seconds. Barium ion concentration slowly increased over a wide area of sky until measurements were discontinued at sunrise (about 30 minutes).

  3. Surface studies of barium and barium oxide on tungsten and its application to understanding the mechanism of operation of an impregnated tungsten cathode

    NASA Technical Reports Server (NTRS)

    Forman, R.

    1976-01-01

    Surface studies have been made of multilayer and monolayer films of barium and barium oxide on a tungsten substrate. The purpose of the investigation was to synthesize the surface conditions that exist on an activated impregnated tungsten cathode and obtain a better understanding of the mechanism of operation of such cathodes. The techniques employed in these measurements were Auger spectroscopy and work-function measurements. The results of this study show that the surface of an impregnated cathode is identical to that observed for a synthesized monolayer or partial monolayer of barium on oxidized tungsten by evaluating Auger spectra and work-function measurements. Data obtained from desorption studies of barium monolayers on a tungsten substrate in conjunction with Auger and work-function results have been interpreted to show that throughout most of its life an impreganated cathode has a partial monolayer, rather than a monolayer, of barium on its surface.

  4. Dielectric function for doped graphene layer with barium titanate

    NASA Astrophysics Data System (ADS)

    Martinez Ramos, Manuel; Garces Garcia, Eric; Magana, Fernado; Vazquez Fonseca, Gerardo Jorge

    2015-03-01

    The aim of our study is to calculate the dielectric function for a system formed with a graphene layer doped with barium titanate. Density functional theory, within the local density approximation, plane-waves and pseudopotentials scheme as implemented in Quantum Espresso suite of programs was used. We considered 128 carbon atoms with a barium titanate cluster of 11 molecules as unit cell with periodic conditions. The geometry optimization is achieved. Optimization of structural configuration is performed by relaxation of all atomic positions to minimize their total energies. Band structure, density of states and linear optical response (the imaginary part of dielectric tensor) were calculated. We thank Dirección General de Asuntos del Personal Académico de la Universidad Nacional Autónoma de México, partial financial support by Grant IN-106514 and we also thank Miztli Super-Computing center the technical assistance.

  5. Particularities of Radiation Defect Formation in Ceramic Barium Cerate

    NASA Astrophysics Data System (ADS)

    Khromushin, I. V.; Aksenova, T. I.; Tuseev, T.; Munasbaeva, K. K.; Ermolaev, Yu V.; Ermolaev, V. N.; Seitov, A. S.

    2015-04-01

    The effects of irradiation with electrons, ions of noble gases (Ne, Ar, Kr) and oxygen on the structure and properties of neodymium-doped barium cerate have been studied using the methods of X-ray diffraction analysis, scanning electron and atomic force microscopy, thermal desorption spectroscopy. It was shown that irradiation by low-energy ions of noble gases stimulates the blistering processes on the sample surface, while the high-energy ions contribute to formation of the structures on the irradiated surface that resemble the various stages of spherulitegrowth. The similar structures were not observed in the case of irradiation with high-energy oxygen ions. According to the data on thermal desorption of water and oxygen molecules from the irradiated barium cerate it was supposed that irradiation by the noble gas ions promotes neodymium oxidation state change. It was noticed that the electron irradiation leads to the formation of the nano-sized acicular structures on the cerate surface.

  6. Absolute Te_2 reference for barium ion at 4554 nm

    NASA Astrophysics Data System (ADS)

    Dutta, Tarun; De Munshi, Debashis; Mukherjee, Manas

    2016-06-01

    Precision atomic spectroscopy is presently the work horse in quantum information technology, metrology, trace analysis and even for fundamental tests in physics. Stable lasers are inherent part of precision spectroscopy which in turn requires absolute wavelength markers suitably placed corresponding to the atomic species being probed. Here we present, new lines of tellurium (Te$_2$) which allows locking of external cavity diode laser (ECDL) for precision spectroscopy of singly charged barium ions. In addition, we have developed an ECDL with over 100 GHz mod-hop-free tuning range using commercially available diode from $\\textit{Nichia}$. These two developments allow nearly drift-free operation of a barium ion trap set-up with one single reference cell thereby reducing the complexity of the experiment.

  7. Barium titanate nanoparticles: promising multitasking vectors in nanomedicine

    NASA Astrophysics Data System (ADS)

    Graziana Genchi, Giada; Marino, Attilio; Rocca, Antonella; Mattoli, Virgilio; Ciofani, Gianni

    2016-06-01

    Ceramic materials based on perovskite-like oxides have traditionally been the object of intense interest for their applicability in electrical and electronic devices. Due to its high dielectric constant and piezoelectric features, barium titanate (BaTiO3) is probably one of the most studied compounds of this family. Recently, an increasing number of studies have been focused on the exploitation of barium titanate nanoparticles (BTNPs) in the biomedical field, owing to the high biocompatibility of BTNPs and their peculiar non-linear optical properties that have encouraged their use as nanocarriers for drug delivery and as label-free imaging probes. In this review, we summarize all the recent findings about these ‘smart’ nanoparticles, including the latest, most promising potential as nanotransducers for cell stimulation.

  8. NASA/Max Planck Institute Barium Ion Cloud Project.

    NASA Technical Reports Server (NTRS)

    Brence, W. A.; Carr, R. E.; Gerlach, J. C.; Neuss, H.

    1973-01-01

    NASA and the Max Planck Institute for Extraterrestrial Physics (MPE), Munich, Germany, conducted a cooperative experiment involving the release and study of a barium cloud at 31,500 km altitude near the equatorial plane. The release was made near local magnetic midnight on Sept. 21, 1971. The MPE-built spacecraft contained a canister of 16 kg of Ba CuO mixture, a two-axis magnetometer, and other payload instrumentation. The objectives of the experiment were to investigate the interaction of the ionized barium cloud with the ambient medium and to deduce the properties of electric fields in the proximity of the release. An overview of the project is given to briefly summarize the organization, responsibilities, objectives, instrumentation, and operational aspects of the project.

  9. The Skylab barium plasma injection experiments. I - Convection observations

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Davis, T. N.; Peek, H. M.

    1976-01-01

    Two barium-plasma injection experiments were carried out during magnetically active periods in conjunction with the Skylab 3 mission. The high-explosive shaped charges were launched near dawn on November 27 and December 4, 1973, UT. In both cases, the AE index was near 400 gammas, and extensive pulsating auroras covered the sky. The first experiment, Skylab Alpha, occurred in the waning phase of a 1000-gamma substorm, and the second, Skylab Beta, occurred in the expansive phase of an 800-gamma substorm. In both, the convection was generally magnetically eastward, with 100-km-level electric fields near 40 mV/m. However, in the Alpha experiment the observed orientation of the barium flux tube fit theoretical field lines having no parallel current, but the Beta flux-tube orientation indicated a substantial upward parallel sheet current.

  10. Observations and theory of the AMPTE magnetotail barium releases

    NASA Technical Reports Server (NTRS)

    Bernhardt, P. A.; Roussel-Dupre, R. A.; Pongratz, M. B.; Haerendel, G.; Valenzuela, A.

    1987-01-01

    The barium releases in the magnetotail during the Active Magnetospheric Particle Tracer Explorers (AMPTE) operation were monitored by ground-based imagers and by instruments on the Ion Release Module. After each release, the data show the formation of a structured diamagnetic cavity. The cavity grows until the dynamic pressure of the expanding ions balances the magnetic pressure on its surface. The magnetic field inside the cavity is zero. The barium ions collect on the surface of the cavity, producing a shell. Plasma irregularities form along magnetic field lines draped over the surface of the cavity. The scale size of the irregularities is nearly equal to the thickness of the shell. The evolution and structuring of the diamagnetic cavity are modeled using magnetohydrodynamics theory.

  11. Numerical simulation of a radially injected barium cloud

    NASA Technical Reports Server (NTRS)

    Swift, D. W.; Wescott, E. M.

    1981-01-01

    Electrostatic two-dimensional numerical simulations of a radially symmetric barium injection experiment demonstrate that ions created by solar UV irradiation are electrostatically bound to the electrons which remain tied to the field lines on which they are created. Two possible instabilities are identified, but neither of them causes the barium plasma cloud to polarize in a way that would permit the plasma to keep up with the neutrals. In a second model, the velocity of the neutrals is allowed to be a function of the azimuthal angle. Here, a portion of the cloud does polarize in a way that allows a portion of the plasma to detach and move outward at the approximate speed of the neutrals. No rapid detachment is found when only the density of the neutrals is given an azimuthal asymmetry.

  12. Study of the photovoltaic effect in thin film barium titanate

    NASA Technical Reports Server (NTRS)

    Grannemann, W. W.; Dharmadhikari, V. S.

    1982-01-01

    Ferroelectric films of barium titanate were synthesized on silicon and quartz substrates, and the photoelectric effect in the structure consisting of metal deposited ferroelectric barium titanate film silicon was studied. A photovoltage with polarity that depends on the direction of the remanent polarization was observed. The deposition of BaTiO3 on silicon and fused quartz substrates was accomplished by an rf sputtering technique. A series of experiments to study the growth of ferroelectric BaTiO3 films on single crystal silicon and fused quartz substrates were conducted. The ferroelectric character in these films was found on the basis of evidence from the polarization electric field hysteresis loops, capacitance voltage and capacitance temperature techniques and from X-ray diffraction studies.

  13. Barium titanate nanoparticles: promising multitasking vectors in nanomedicine.

    PubMed

    Genchi, Giada Graziana; Marino, Attilio; Rocca, Antonella; Mattoli, Virgilio; Ciofani, Gianni

    2016-06-10

    Ceramic materials based on perovskite-like oxides have traditionally been the object of intense interest for their applicability in electrical and electronic devices. Due to its high dielectric constant and piezoelectric features, barium titanate (BaTiO3) is probably one of the most studied compounds of this family. Recently, an increasing number of studies have been focused on the exploitation of barium titanate nanoparticles (BTNPs) in the biomedical field, owing to the high biocompatibility of BTNPs and their peculiar non-linear optical properties that have encouraged their use as nanocarriers for drug delivery and as label-free imaging probes. In this review, we summarize all the recent findings about these 'smart' nanoparticles, including the latest, most promising potential as nanotransducers for cell stimulation. PMID:27145888

  14. Barium borohydride chlorides: synthesis, crystal structures and thermal properties.

    PubMed

    Grube, Elisabeth; Olesen, Cathrine H; Ravnsbæk, Dorthe B; Jensen, Torben R

    2016-05-10

    Here we report the synthesis, mechanism of formation, characterization and thermal decomposition of new barium borohydride chlorides prepared by mechanochemistry and thermal treatment of MBH4-BaCl2, M = Li, Na or K in ratios 1 : 1 and 1 : 2. Initially, orthorhombic barium chloride, o-BaCl2 transforms into o-Ba(BH4)xCl2-x, x ∼ 0.15. Excess LiBH4 leads to continued anion substitution and a phase transformation into hexagonal barium borohydride chloride h-Ba(BH4)xCl2-x, which accommodates higher amounts of borohydride, possibly x ∼ 0.85 and resembles h-BaCl2. Thus, two solid solutions are in equilibrium during mechano-chemical treatment of LiBH4-BaCl2 (1 : 1) whereas LiBH4-BaCl2 (2 : 1) converts to h-Ba(BH4)0.85Cl1.15. Upon thermal treatment at T > ∼200 °C, h-Ba(BH4)0.85Cl1.15 transforms into another orthorhombic barium borohydride chloride compound, o-Ba(BH4)0.85Cl1.15, which is structurally similar to o-BaBr2. The samples with M = Na and K have lower reactivity and form o-Ba(BH4)xCl2-x, x ∼ 0.1 and a solid solution of sodium chloride dissolved in solid sodium borohydride, Na(BH4)1-xClx, x = 0.07. The new compounds and reaction mechanisms are investigated by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), Fourier transform infrared spectroscopy (FT-IR) and simultaneous thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mass spectroscopy (MS) and temperature programmed photographic analysis (TPPA). PMID:27109871

  15. Synthesis and characterization of barium ferrite–silica nanocomposites

    SciTech Connect

    Aguilar-González, M.A.; Mendoza-Suárez, G.; Padmasree, K.P.

    2013-10-15

    In this work, we prepared barium ferrite-silica (BaM-SiO{sub 2}) nanocomposites of different molar ratios by high-energy ball milling, followed by heat-treatment at different temperatures. The microstructure, morphology and magnetic properties were characterized for different synthesis conditions by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). The results indicate that 15 h of milling was enough to avoid the generation of hematite phase and to get a good dispersion of barium ferrite particles in the ceramic matrix. For milling periods beyond 15 h and heat treatment above 900 °C, the XRD patterns showed the presence of hematite phase caused by the decomposition of BaM. The agglomerate size observed through SEM analysis was around 150 nm with a good BaM dispersion into the SiO{sub 2} matrix. The highest saturation magnetization (Ms) value obtained was 43 emu/g and the corresponding coercivity (Hc) value of 3.4 kOe for the composition 60BaM-40SiO{sub 2} milled for 15 h and heat treated at 900 °C. This coercivity value is acceptable for the application in magnetic recording media. Highlights: • Barium ferrite–silica nanocomposites were prepared by high energy ball milling. • Optimal processing time is 15 h milling and heat treatment at 900 °C. • This is enough to avoid the generation of hematite phase. • Obtain good dispersion of barium ferrite particles in the ceramic matrix • Above this processing time shows the presence of increased amount of hematite.

  16. Layer morphology and growth mechanisms in barium ferrites

    NASA Astrophysics Data System (ADS)

    Turner, G.; Stewart, B.; Baird, T.; Peacock, R. D.; Cairns-Smith, A. G.

    1996-01-01

    Crystals of hexagonal barium ferrites have been grown using a standard flux technique and, as a modification, on platinum tabs removed early from the hot flux. Products have been examined by SEM. Mature crystals often show highly laminated structures. Early crystals may consist of thin, somewhat flexible plates or slabs which overgrow themselves in ways which provide a possible explanation for the long c-axis repeats previously reported in these materials.

  17. Acute barium intoxication following ingestion of soap water solution

    PubMed Central

    Joshi, Nandita; Sharma, Chhavi Sarabpreert; Sai; Sharma, Jai Prakash

    2012-01-01

    We present a rare case in which a young girl ingested a solution of a hair-removing soap. The ingestion resulted in profound hypokalemia and severe acidosis leading to flaccid paralysis, respiratory arrest and ventricular arrhythmias. Ultimately the patient made complete recovery. The soapwas found to contain barium sulfide. The degree of paralysis and acidosis appeared to be directly related to serum potassium levels. PMID:23559738

  18. Life Model of Hollow Cathodes Using a Barium Calcium Aluminate Impregnated Tungsten Emitter

    NASA Technical Reports Server (NTRS)

    Kovaleski, S. D.; Burke, Tom (Technical Monitor)

    2001-01-01

    Hollow cathodes with barium calcium aluminate impregnated tungsten emitters for thermionic emission are widely used in electric propulsion. These high current, low power cathodes are employed in ion thrusters, Hall thrusters, and on the International Space Station in plasma contactors. The requirements on hollow cathode life are growing more stringent with the increasing use of electric propulsion technology. The life limiting mechanism that determines the entitlement lifetime of a barium impregnated thermionic emission cathode is the evolution and transport of barium away from the emitter surface. A model is being developed to study the process of barium transport and loss from the emitter insert in hollow cathodes. The model accounts for the production of barium through analysis of the relevant impregnate chemistry. Transport of barium through the approximately static gas is also being treated. Finally, the effect of temperature gradients within the cathode are considered.

  19. The Tordo 1 polar cusp barium plasma injection experiment

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Davis, T. N.; Jeffries, R. A.; Roach, W. H.

    1978-01-01

    In January 1975, two barium plasma injection experiments were carried out with rockets launched into the upper atmosphere where field lines from the dayside cusp region intersect the ionosphere. The Tordo 1 experiment took place near the beginning of a worldwide magnetic storm. It became a polar cap experiment almost immediately as convection perpendicular to the magnetic field moved the fluorescent plasma jet away from the cusp across the polar cap in an antisunward direction. Convection across the polar cap with an average velocity of more than 1 km/s was observed for nearly 40 min until the barium flux tubes encountered large electron fields associated with a poleward bulge of the auroral oval near Greenland. Prior to the encounter with the aurora near Greenland there is evidence of upward acceleration of the barium ions while they were in the polar cap. The three-dimensional observations of the plasma orientation and motion give an insight into convection from the cusp region across the polar cap, the orientation of the polar cap magnetic field lines out to several earth radii, the causes of polar cap magnetic perturbations, and parallel acceleration processes.

  20. Barium aluminosilicate reinforced in situ with silicon nitride

    SciTech Connect

    Richardson, K.K.; Freitag, D.W.; Hunn, D.L.

    1995-10-01

    Advanced ceramic composite materials that exhibit high strength and toughness with good thermal shock resistance are needed for emerging high-temperature engineering applications. A recently developed in situ reinforced barium aluminosilicate glass-ceramic shows promise of meeting many of the requirements for these types of applications with the added benefit of low-cost fabrication through densification by pressureless sintering. The material is toughened through in situ growth of rodlike {beta}-Si{sub 3}N{sub 4} grains resulting from the {alpha}-{beta} silicon nitride phase transformation. Microstructural development and material properties for temperatures up to 1,400 C are discussed. When compared to monolithic barium aluminosilicate, barium aluminosilicate reinforced with 70% by volume of Si{sub 3}N{sub 4} shows a significant increase in flexural strength (from 80 to 565 MPa) and fracture toughness (from 1.8 to 5.74 MPa {center_dot} m{sup 1/2}) with a high resistance to thermal shock.

  1. Mechanism of action of barium ion on rat aortic smooth muscle.

    PubMed

    Hansen, T R; Dineen, D X; Petrak, R

    1984-03-01

    The mechanism of action of barium ion on the aortic smooth muscle of the normal rat was investigated using in vitro calcium-depleted aortic strips. Aortic strips were depleted of calcium by repeated exposure to norepinephrine in a calcium-free bathing solution. Although calcium depletion abrogated the response of strips to catecholamines and depolarizing agents, the response to barium chloride remained quantitatively intact. The calcium influx blocker D 600 prevented the contractile response to barium but not to catecholamines, whereas phentolamine prevented the response to catecholamines but not barium. The strip response to barium was depressed by a twofold increase in extracellular magnesium concentration whether the strip was intact or calcium depleted. Although increased concentrations of calcium in the extracellular medium inhibited the contractile response to potassium ion, increases in barium merely potentiated the potassium contracture. These findings indicate that barium produces its contractile effect on vascular smooth muscle by a direct intracellular interaction with the contractile or regulatory proteins. Barium enters these cells via calcium influx channels and is probably not sequestered in a physiologically releasable pool. Unlike calcium, barium does not stabilize the smooth muscle sarcolemma when present in high concentration. PMID:6703038

  2. Barium can replace calcium in calmodulin-dependent contractions of skinned renal arteries of the rabbit.

    PubMed

    Kreye, V A; Hofmann, F; Mühleisen, M

    1986-03-01

    Renal arteries of the rabbit were chemically skinned using Triton X-100. In EGTA-buffered solutions containing calmodulin and ATP, small strips of the skinned preparations were found to develop contractile force which was dependent on the concentrations of either free calcium or of free barium. However, a 220 times greater concentration of barium than of calcium was necessary for comparable effects. Quantitatively, the response to barium was dependent on the concentration of calmodulin added to the test solutions. The contractile effect of barium was partly antagonized by the calmodulin antagonist, trifluoperazine. PMID:3960707

  3. Beam patterns in an optical parametric oscillator set-up employing walk-off compensating beta barium borate crystals

    NASA Astrophysics Data System (ADS)

    Kaucikas, M.; Warren, M.; Michailovas, A.; Antanavicius, R.; van Thor, J. J.

    2013-02-01

    This paper describes the investigation of an optical parametric oscillator (OPO) set-up based on two beta barium borate (BBO) crystals, where the interplay between the crystal orientations, cut angles and air dispersion substantially influenced the OPO performance, and especially the angular spectrum of the output beam. Theory suggests that if two BBO crystals are used in this type of design, they should be of different cuts. This paper aims to provide an experimental manifestation of this fact. Furthermore, it has been shown that air dispersion produces similar effects and should be taken into account. An x-ray crystallographic indexing of the crystals was performed as an independent test of the above conclusions.

  4. Angiography contrast injector safety. Visualizing the marketplace.

    PubMed

    2010-06-01

    The most common risk associated with angiography contrast injectors is air embolism. Injector manufacturers have attempted to address this concern by adding air detection systems and other safety features. Find out which injectors do the best job of protecting patients. PMID:21309283

  5. High contrast computed tomography with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Itai, Yuji; Takeda, Tohoru; Akatsuka, Takao; Maeda, Tomokazu; Hyodo, Kazuyuki; Uchida, Akira; Yuasa, Tetsuya; Kazama, Masahiro; Wu, Jin; Ando, Masami

    1995-02-01

    This article describes a new monochromatic x-ray CT system using synchrotron radiation with applications in biomedical diagnosis which is currently under development. The system is designed to provide clear images and to detect contrast materials at low concentration for the quantitative functional evaluation of organs in correspondence with their anatomical structures. In this system, with x-ray energy changing from 30 to 52 keV, images can be obtained to detect various contrast materials (iodine, barium, and gadolinium), and K-edge energy subtraction is applied. Herein, the features of the new system designed to enhance the advantages of SR are reported. With the introduction of a double-crystal monochromator, the high-order x-ray contamination is eliminated. The newly designed CCD detector with a wide dynamic range of 60 000:1 has a spatial resolution of 200 μm. The resulting image quality, which is expected to show improved contrast and spatial resolution, is currently under investigation.

  6. Nanoparticle Contrast Agents for Computed Tomography: A Focus on Micelles

    PubMed Central

    Cormode, David P.; Naha, Pratap C.; Fayad, Zahi A.

    2014-01-01

    Computed tomography (CT) is an X-ray based whole body imaging technique that is widely used in medicine. Clinically approved contrast agents for CT are iodinated small molecules or barium suspensions. Over the past seven years there has been a great increase in the development of nanoparticles as CT contrast agents. Nanoparticles have several advantages over small molecule CT contrast agents, such as long blood-pool residence times, and the potential for cell tracking and targeted imaging applications. Furthermore, there is a need for novel CT contrast agents, due to the growing population of renally impaired patients and patients hypersensitive to iodinated contrast. Micelles and lipoproteins, a micelle-related class of nanoparticle, have notably been adapted as CT contrast agents. In this review we discuss the principles of CT image formation and the generation of CT contrast. We discuss the progress in developing non-targeted, targeted and cell tracking nanoparticle CT contrast agents. We feature agents based on micelles and used in conjunction with spectral CT. The large contrast agent doses needed will necessitate careful toxicology studies prior to clinical translation. However, the field has seen tremendous advances in the past decade and we expect many more advances to come in the next decade. PMID:24470293

  7. Tungsten and barium transport in the internal plasma of hollow cathodes

    NASA Astrophysics Data System (ADS)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2009-06-01

    The effect of tungsten erosion, transport, and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from 8200 h and 30 352 h ion engine wear tests. Erosion and subsequent redeposition of tungsten in the electron emission zone at the downstream end of the insert reduce the porosity of the tungsten matrix, preventing the flow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  8. A review of the health impacts of barium from natural and anthropogenic exposure.

    PubMed

    Kravchenko, Julia; Darrah, Thomas H; Miller, Richard K; Lyerly, H Kim; Vengosh, Avner

    2014-08-01

    There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food

  9. The effect of barium on perceptions of taste intensity and palatability.

    PubMed

    Dietsch, Angela M; Solomon, Nancy Pearl; Steele, Catriona M; Pelletier, Cathy A

    2014-02-01

    Barium may affect the perception of taste intensity and palatability. Such differences are important considerations in the selection of dysphagia assessment strategies and interpretation of results. Eighty healthy women grouped by age (younger, older) and genetic taste status (supertaster, nontaster) rated intensity and palatability for seven tastants prepared in deionized water with and without 40 % w/v barium: noncarbonated and carbonated water, diluted ethanol, and high concentrations of citric acid (sour), sodium chloride (salty), caffeine (bitter), and sucrose (sweet). Mixed-model analyses explored the effects of barium, taster status, and age on perceived taste intensity and acceptability of stimuli. Barium was associated with lower taste intensity ratings for sweet, salty, and bitter tastants, higher taste intensity in carbonated water, and lower palatability in water, sweet, sour, and carbonated water. Older subjects reported lower palatability (all barium samples, sour) and higher taste intensity scores (ethanol, sweet, sour) compared to younger subjects. Supertasters reported higher taste intensity (ethanol, sweet, sour, salty, bitter) and lower palatability (ethanol, salty, bitter) than nontasters. Refusal rates were highest for younger subjects and supertasters, and for barium (regardless of tastant), bitter, and ethanol. Barium suppressed the perceived intensity of some tastes and reduced palatability. These effects are more pronounced in older subjects and supertasters, but younger supertasters are least likely to tolerate trials of barium and strong tastant solutions. PMID:24037100

  10. 75 FR 36629 - Barium Chloride From the People's Republic of China: Continuation of Antidumping Duty Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-28

    ... Barium Chloride From China, 75 FR 33824 (June 15, 2010), and Barium Chloride from China (Inv. No. 731-TA... Five-year (``Sunset'') Review, 74 FR 31412 (July 1, 2009). As a result of its review, the Department... China: Final Results of Expedited Third Sunset Review of Antidumping Duty Order, 74 FR 55814 (October...

  11. Description of the barium cloud vectoring systems developed for the PLACES test series

    SciTech Connect

    Finnell, R.T.

    1981-05-01

    The PLACES experiments were conducted to investigate the effects of ionospheric plasmas (created by barium vapor released from rockets) on satellite communications and navigation systems. Launcher setting angles for the rockets were provided by a minicomputer system made up of four subsystems. This report describes the subsystems which determined the barium cloud vectors from TV data alone and from combined radar/TV data.

  12. LACK OF EFFECT OF DRINKING WATER BARIUM ON CARDIOVASCULAR RISK FACTORS

    EPA Science Inventory

    Higher cardiovascular mortality has been associated in a single epidemiological study with higher levels of barium in drinking water. he purpose of this study was to determine whether drinking water barium at levels found in some U.S. communities alters the known risk factors for...

  13. Agglomeration behavior of solid nickel on polycrystalline barium titanate

    SciTech Connect

    Weil, K Scott; Mast, Eric S; Sprenkle, Vince

    2007-11-01

    This letter describes the phenomenon that takes place between nickel/barium titanate couples when heated under conditions employed in multilayer ceramic capacitor manufacturing practice: a 4hr, 1300°C isothermal anneal in 1% H2 – 99% N2. Dense, sputtered nickel films were observed to dewet the titanate and agglomerate into discrete or interconnected islands via a solid-state process. Up to a critical film thickness value of ~1.4 μm, the degree of agglomeration was found to display an exponential dependence on the thickness of the original nickel film.

  14. Defect chemistry and proton conductivity in barium-based perovskites

    NASA Astrophysics Data System (ADS)

    Wu, Jian

    The site incorporation mechanism of M3+ dopats into A 2+B4+O3 perovskites controls the overall defect chemistry and thus their transport properties. For charge balance reasons, incorporation onto the A2+ site would require the creation of negatively charged point defects, such as cation vacancies, whereas incorporation onto the B4+ site is accompanied by the generation of positively charged defects, typically oxygen vacancies. Oxygen vacancy content, in turn, is relevant to proton conducting oxides in which protons are introduced via the dissolution of hydroxyl ions at vacant oxygen sites. This work proposes that, on the basis of X-ray powder diffraction studies, electron microscopy, chemical analysis, thermal gravimetric analysis, AC impedance spectroscopy, extended X-ray fine structure (EXAFS) and atomistic simulation, that nominally B-site doped barium cerate can exhibit dopant partitioning partially as a consequence of barium evaporation at elevated temperatures. Such partitioning and the presence of significant dopant concentrations on the A-site negatively impact proton conductivity. As a consequence of the greater ability of larger cations to exist on the Ba site, the H2O adsorption and proton conductivities of large-cation doped barium cerates are lower than those of small-cation doped analogs. A series of dopats, La, Nd, Sm, Gd and Yb are adopted in doped BaCeO 3 with the composition BaCe0.85M0.15O3-delta . Yb doped BaCeO3 yields the highest proton conductivity among all the doped samples. Compositional non-stoichiometry, which is closely tied to sample processing, is studied in a BaXCe0.85M 0.15O3+/-delta series. It is indicated that low temperature synthesis is beneficial to reduce barium evaporation at elevated temperatures and in turn increase the proton conductivity. The chemical stability of BaCeO 3 is investigated and Zr is used to stabilize BaCeO3 in CO 2-rich atmosphere effectively. This result helps to commercialize doped BaCeO3 as the

  15. The barium ion jet experiments of the Porcupine project

    NASA Astrophysics Data System (ADS)

    Haerendel, G.

    1980-06-01

    The injection of a barium plasma from a sounding rocket by the shaped charge technique offers several possibilities that cannot be achieved by conventional releases. This is due to high initial velocities of the atoms of up to 14 km/sec. Most of the the applications are related to the great heights that the ions can reach, but some depend directly on the initial momentum. Typical applications are: tracing at high altitudes, modifications, and alternate Ionization processes. Project Porcupine contributions in this field are summarized.

  16. Radium and barium in the Amazon River system

    SciTech Connect

    Moore, W.S.; Edmond, J.M.

    1984-03-20

    Data for /sup 226/Ra and /sup 228/Ra in the Amazon River system show that the activity of each radium isotope is strongly correlated with barium concentrations. Two trends are apparent, one for rivers which drain shield areas and another for all other rivers. These data suggest that there has been extensive fractionation of U, Th, and Ba during weathering in the Amazon basin. The /sup 226/Ra data fit a flux model for the major ions indicating that /sup 226/Ra behaves conservatively along the main channel of the Amazon River.

  17. Nanodielectric system for cryogenic applications: Barium titanate filled polyvinyl alcohol

    SciTech Connect

    Tuncer, Enis; Sauers, Isidor; James, David Randy; Ellis, Alvin R; Duckworth, Robert C

    2008-01-01

    In the current study the focus is on dielectric properties (as a function of frequency and temperature) of a polymeric composite system composed of polyvinyl alcohol and barium titanate nano powder. In the investigations, the temperature range is between 50-295 K, and the frequency range is between $20\\ \\hertz-1\\ \\mega\\hertz$. Polarization and conduction processes are investigated in the linear regime. Dielectric breakdown strengths of samples are also reported. The materials presented have potential to be implemented in cryogenic capacitor or field grading applications.

  18. Magnetic and structural investigations on barium hexaferrite ferrofluids

    NASA Astrophysics Data System (ADS)

    Müller, R.; Hiergeist, R.; Gawalek, W.; Hoell, A.; Wiedenmann, A.

    2002-11-01

    Barium hexaferrite BaFe 12-2 xTi xCo xO 19 ferrofluids have been prepared using oleic acid as surfactant and Isopar M ® or dodecane as carrier liquid. The ferrite particles were prepared by glass crystallization. Hysteresis parameters, the initial susceptibility versus temperature and the magnetic particle size were obtained by VSM. Ferrofluids with a partly deuterated carrier liquid were investigated by small angle neutron scattering (SANS). SANS curves lead to a bimodal size distribution consisting of single magnetic particles with an organic shell and aggregated particles with an incomplete organic layer.

  19. Enhanced flexoelectricity through residual ferroelectricity in barium strontium titanate

    SciTech Connect

    Garten, Lauren M. Trolier-McKinstry, Susan

    2015-03-07

    Residual ferroelectricity is observed in barium strontium titanate ceramics over 30 °C above the global phase transition temperature, in the same temperature range in which anomalously large flexoelectric coefficients are reported. The application of a strain gradient leads to strain gradient-induced poling or flexoelectric poling. This was observed by the development of a remanent polarization in flexoelectric measurements, an induced d{sub 33} piezoelectric response even after the strain gradient was removed, and the production of an internal bias of 9 kV m{sup −1}. It is concluded that residual ferroelectric response considerably enhances the observed flexoelectric response.

  20. Strain engineered barium strontium titanate for tunable thin film resonators

    SciTech Connect

    Khassaf, H.; Khakpash, N.; Sun, F.; Sbrockey, N. M.; Tompa, G. S.; Kalkur, T. S.; Alpay, S. P.

    2014-05-19

    Piezoelectric properties of epitaxial (001) barium strontium titanate (BST) films are computed as functions of composition, misfit strain, and temperature using a non-linear thermodynamic model. Results show that through adjusting in-plane strains, a highly adaptive rhombohedral ferroelectric phase can be stabilized at room temperature with outstanding piezoelectric response exceeding those of lead based piezoceramics. Furthermore, by adjusting the composition and the in-plane misfit, an electrically tunable piezoelectric response can be obtained in the paraelectric state. These findings indicate that strain engineered BST films can be utilized in the development of electrically tunable and switchable surface and bulk acoustic wave resonators.

  1. Barium dierbium(III) tetra­sulfide

    PubMed Central

    Mesbah, Adel; Stojko, Wojciech; Ibers, James. A

    2013-01-01

    Barium dierbium(III) tetra­sulfide, BaEr2S4, crystallizes with four formula units in the ortho­rhom­bic space group Pnma in the CaFe2O4 structure type. The asymmetric unit contains two Er, one Ba, and four S atoms, each with .m. site symmetry. The structure consists of channels formed by corner- and edge-sharing ErS6 octa­hedra in which Ba atoms reside. The resultant coordination of Ba is that of a bicapped trigonal prism. PMID:23476480

  2. Barium impaction therapy with balloon occlusion for deep colonic diverticular bleeding: a three-case series

    PubMed Central

    Koga, Mikinori; Kusano, Chika; Gotoda, Takuji; Suzuki, Sho; Sato, Takemasa; Fukuzawa, Masakatsu; Itoi, Takao; Moriyasu, Fuminori

    2016-01-01

    Background and aims: In hemostasis for colonic diverticular bleeding, the incidence of recurrent bleeding is higher in deep colonic diverticulum than in shallow. We aimed to improve and evaluate barium impaction therapy using an enteroscopic overtube with balloon. Patients and method: We performed barium impaction therapy in three patients with a diagnosis of deep colonic diverticular bleeding. The tip of the overtube was inserted to reach the cecum using the conventional method. After deflating the colon, the enteroscope was removed. The balloon in the tube was inflated, followed by barium filling via the tube. Sufficient pressure was applied by ensuring no regurgitation into the small intestine side. The entire colon was continuously filled with barium in stages. Results: Post-treatment bleeding was controllable without adverse events in all three patients. Conclusion: This novel barium impaction therapy using an enteroscopic overtube with balloon was effectively performed without adverse events. PMID:27227115

  3. Setting process of lime-based conservation mortars with barium hydroxide

    SciTech Connect

    Karatasios, Ioannis . E-mail: ikarat@ims.demokritos.gr; Kilikoglou, Vassilis; Colston, Belinda; Theoulakis, Panagiotis; Watt, David

    2007-06-15

    This paper presents the effect of barium hydroxide on the setting mechanism of lime-based conservation mortars, when used as an additive material. The study focuses on the monitoring of the setting process and the identification of the mineral phases formed, which are essential for furthering the study of the durability of barium mixtures against chemical degradation. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and thermal analysis (DTA-TG) were used to monitor the setting processes of these mixtures and identify new phases formed. The results suggest that barium hydroxide is evenly distributed within the lime and produces a homogeneous binding material, consisting of calcite (CaCO{sub 3}), witherite (BaCO{sub 3}) and barium-calcium carbonate [BaCa(CO{sub 3}){sub 2}]. Finally, it was found that barium carbonate can be directly bonded to calcitic aggregates and therefore increases its chemical compatibility with the binding material.

  4. Occultation of the ATS-3 satellite by the AVEFRIA barium ion cloud

    SciTech Connect

    Fitzgerald, T.J.; Simons, D.J.; Pongratz, M.B.; Clynch, J.R.

    1981-01-01

    During the AVEFRIA DOS barium release experiment, sponsored by the Los Alamos National Laboratory and the Defense Nuclear Agency in May 1978, the line of sight from one of the ground observation stations to the ATS-3 satellite was occulted by the barium ion cloud for a period of approximately five minutes. Optical measurements of the structured barium ion cloud were made with intensified cameras using the 455.4-nm wavelength fluorescent ion line. These measurements have been related to barium ion column density. During the occultation, the amplitude scintillations of the 136.47-MHz signal from the ATS-3 satellite were monitored. The optical measurements have been used to correlate the barium column density with the total electron content measurements and to calculate the scintillation index, S/sub 4/, and the two dimensional intensity pattern for comparison with the measured amplitude scintillations.

  5. Determination of Barium and selected rare-earth elements in geological materials employing a HpGe detector by radioisotope excited x-ray fluorescence

    SciTech Connect

    LaBrecque, J.J.; Preiss, I.L.

    1984-01-01

    The laterite material (geological) from Cerro Impacto was first studied by air radiometric techniques in the 1970's and was found to have an abnormally high radioactive background. Further studies showed this deposit to be rich in thorium, columbium, barium and rare-earth elements (mostly La, Ce, Pr and Nd). A similar work has been reported for the analysis of Brazil's lateritic material from Morro do Ferro to determine elemental compositions (including barium and rare-earth elements) and its relationship to the mobilization of thorium from the deposit using a Co-57 radioisotope source. The objective of this work was to develop an analytical method to determine barium and rare-earth element present in Venezuelan lateritic material from Cerro Impacto. We have employed a method before, employing a Si(Li) detector, but due to the low detection efficiencies in the rare-earth K-lines region (about 30 KeV - 40 KeV), we have decided to study the improvement in sensitivities and detection limits using an hyperpure germanium detector.

  6. Complementary contrast media for metal artifact reduction in dual-energy computed tomography.

    PubMed

    Lambert, Jack W; Edic, Peter M; FitzGerald, Paul F; Torres, Andrew S; Yeh, Benjamin M

    2015-07-01

    Metal artifacts have been a problem associated with computed tomography (CT) since its introduction. Recent techniques to mitigate this problem have included utilization of high-energy (keV) virtual monochromatic spectral (VMS) images, produced via dual-energy CT (DECT). A problem with these high-keV images is that contrast enhancement provided by all commercially available contrast media is severely reduced. Contrast agents based on higher atomic number elements can maintain contrast at the higher energy levels where artifacts are reduced. This study evaluated three such candidate elements: bismuth, tantalum, and tungsten, as well as two conventional contrast elements: iodine and barium. A water-based phantom with vials containing these five elements in solution, as well as different artifact-producing metal structures, was scanned with a DECT scanner capable of rapid operating voltage switching. In the VMS datasets, substantial reductions in the contrast were observed for iodine and barium, which suffered from contrast reductions of 97% and 91%, respectively, at 140 versus 40 keV. In comparison under the same conditions, the candidate agents demonstrated contrast enhancement reductions of only 20%, 29%, and 32% for tungsten, tantalum, and bismuth, respectively. At 140 versus 40 keV, metal artifact severity was reduced by 57% to 85% depending on the phantom configuration. PMID:26839905

  7. Tungsten and Barium Transport in the Internal Plasma of Hollow Cathodes

    NASA Technical Reports Server (NTRS)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2008-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the flow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushedback to the emitter surface by the electric field and drag from the xenon ion flow. Thisbarium ion flux is sufficient to maintain a barium surface coverage at the downstream endgreater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length,so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollowcathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  8. Endotrophic Calcium, Strontium, and Barium Spores of Bacillus megaterium and Bacillus cereus1

    PubMed Central

    Foerster, Harold F.; Foster, J. W.

    1966-01-01

    Foerster, Harold F. (The University of Texas, Austin), and J. W. Foster. Endotrophic calcium, strontium, and barium spores of Bacillus megaterium and Bacillus cereus. J. Bacteriol. 91:1333–1345. 1966.—Spores were produced by washed vegetative cells suspended in deionized water supplemented with CaCl2, SrCl2, or BaCl2. Normal, refractile spores were produced in each case; a portion of the barium spores lost refractility and darkened. Thin-section electron micrographs revealed no apparent anatomical differences among the three types of spores. Analyses revealed that the different spore types were enriched specifically in the metal to which they were exposed during sporogenesis. The calcium content of the strontium and the barium spores was very small. From binary equimolar mixtures of the metal salts, endotrophic spores accumulated both metals to nearly the same extent. Viability of the barium spores was considerably less than that of the other two types. Strontium and barium spores were heat-resistant; however, calcium was essential for maximal heat resistance. Significant differences existed in the rates of germination; calcium spores germinated fastest, strontium spores were slower, and barium spores were slowest. Calcium-barium and calcium-strontium spores germinated readily. Endotrophic calcium and strontium spores germinated without the prior heat activation essential for growth spores. Chemical germination of the different metal-type spores with n-dodecylamine took place at the same relative rates as physiological germination. Heat-induced release of dipicolinic acid occurred much faster with barium and strontium spores than with calcium spores. The washed “coat fraction” from disrupted spores contained little of the spore calcium but most of the spore barium. The metal in this fraction was released by dilute acid. The demineralized coats reabsorbed calcium and barium at neutral pH. Images PMID:4956334

  9. Dissolution of Barium from Barite in Sewage Sludges and Cultures of Desulfovibrio desulfuricans

    PubMed Central

    Baldi, F.; Pepi, M.; Burrini, D.; Kniewald, G.; Scali, D.; Lanciotti, E.

    1996-01-01

    High concentrations of total barium, ranging from 0.42 to 1.58 mg(middot)g(sup-1) (dry weight) were found in sludges of two sewage treatment plants near Florence, Italy. Barium concentrations in the suspended matter decreased as redox potential values changed from negative to positive. An anoxic sewage sludge sample was aerated, and 30% of the total barium was removed in 24 h. To demonstrate that barium was solubilized from barite by sulfate-reducing bacteria, a strain of Desulfovibrio desulfuricans was used to study the solubilization of barium from barite under laboratory conditions. During cell growth with different concentrations of barite from 0.01 to 0.3 g(middot)liter(sup-1) (the latter is the MIC) as the only source of sulfates in the cultures, the D. desulfuricans strain accumulated barium up to 0.58 (mu)g(middot)mg(sup-1) (dry weight). Three times the quantity of barium was dissolved by bacteria than in the uninoculated medium (control). The unexpectedly low concentration of soluble barium (1.2 mg of Ba(middot)liter(sup-1)) with respect to the quantity expected (109 mg of Ba(middot)liter(sup-1)), calculated on the basis of the free H(inf2)S evolved from the dissimilatory reduction of sulfate from barite, was probably due to the formation of other barium compounds, such as witherite (BaCO(inf3)) and the transient species barium sulfide (BaS). The D. desulfuricans strain, growing on barite, formed visible aggregates. Confocal microscopy analysis showed that aggregates consisted of bacteria and barite. After 3 days of incubation, several autofluorescent crystals surrounded by a dissolution halo were observed. The crystals were identified as BaS by comparison with the commercial compound. PMID:16535353

  10. Proton trapping in yttrium-doped barium zirconate

    NASA Astrophysics Data System (ADS)

    Yamazaki, Yoshihiro; Blanc, Frédéric; Okuyama, Yuji; Buannic, Lucienne; Lucio-Vega, Juan C.; Grey, Clare P.; Haile, Sossina M.

    2013-07-01

    The environmental benefits of fuel cells have been increasingly appreciated in recent years. Among candidate electrolytes for solid-oxide fuel cells, yttrium-doped barium zirconate has garnered attention because of its high proton conductivity, particularly in the intermediate-temperature region targeted for cost-effective solid-oxide fuel cell operation, and its excellent chemical stability. However, fundamental questions surrounding the defect chemistry and macroscopic proton transport mechanism of this material remain, especially in regard to the possible role of proton trapping. Here we show, through a combined thermogravimetric and a.c. impedance study, that macroscopic proton transport in yttrium-doped barium zirconate is limited by proton-dopant association (proton trapping). Protons must overcome the association energy, 29 kJ mol-1, as well as the general activation energy, 16 kJ mol-1, to achieve long-range transport. Proton nuclear magnetic resonance studies show the presence of two types of proton environment above room temperature, reflecting differences in proton-dopant configurations. This insight motivates efforts to identify suitable alternative dopants with reduced association energies as a route to higher conductivities.

  11. Brillouin function characteristics for La-Co substituted barium hexaferrites

    NASA Astrophysics Data System (ADS)

    Wu, Chuanjian; Yu, Zhong; Yang, Yan; Sun, Ke; Guo, Rongdi; Jiang, Xiaona; Lan, Zhongwen

    2015-09-01

    La-Co substituted barium hexaferrites with the chemical formula of Ba1-xLaxFe12-xCoxO19 (x = 0.0, 0.1, 0.3, and 0.5), prepared by a conventional ceramic method, were systematically investigated by Raman spectra, X-ray photoelectron spectroscopy, Rietveld refinement of X-ray diffraction patterns, and vibrating sample magnetometer. The result manifests that all the compounds are crystallized in magnetoplumbite hexagonal structure. Trivalent cobalt ions prevailingly occupy the 2a, 4f1, and 12k sites. According to Néel model of collinear-spin ferrimagnetism, the molecular-field coefficients ωbf2, ωkf1, ωaf1, ωkf2, and ωbk of La-Co substituted barium hexaferrites have been calculated using the nonlinear fitting method, and the magnetic moment of five sublattices (2a, 2b, 4f1, 4f2, and 12k) versus temperature T has been also investigated. The fitting results are coincided well with the experimental data. Moreover, with the increase of La-Co substitution amount x, the molecular-field coefficients ωbf2 and ωaf1 decrease constantly, while the molecular-field coefficients ωkf1, ωkf2, and ωbk show a slight change.

  12. Results of magnetospheric barium ion cloud experiment of 1971

    NASA Technical Reports Server (NTRS)

    Adamson, D.; Fricke, C. L.; Long, S. A. T.

    1975-01-01

    The barium ion cloud experiment involved the release of about 2 kg of barium at an altitude of 31 482 km, a latitude of 6.926 N., and a longitude of 74.395 W. Significant erosion of plasma from the main ion core occurred during the initial phase of the ion cloud expansion. From the motion of the outermost striational filaments, the electric field components were determined to be 0.19 mV/m in the westerly direction and 0.68 mV/m in the inward direction. The differences between these components and those measured from balloons flown in the proximity of the extremity of the field line through the release point implied the existence of potential gradients along the magnetic field lines. The deceleration of the main core was greater than theoretically predicted. This was attributed to the formation of a polarization wake, resulting in an increase of the area of interaction and resistive dissipation at ionospheric levels. The actual orientation of the magnetic field line through the release point differed by about 10.5 deg from that predicted by magnetic field models that did not include the effect of ring current.

  13. Plasma waves associated with the first AMPTE magnetotail barium release

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Anderson, R. R.; Bernhardt, P. A.; Luehr, H.; Haerendel, G.

    1986-01-01

    Plasma waves observed during the March 21, 1985, AMPTE magnetotail barium release are described. Electron plasma oscillations provided local measurements of the plasma density during both the expansion and decay phases. Immediately after the explosion, the electron density reached a peak of about 400,000/cu cm, and then started decreasing approximately as t to the -2.4 as the cloud expanded. About 6 minutes after the explosion, the electron density suddenly began to increase, reached a secondary peak of about 240/cu cm, and then slowly decayed down to the preevent level over a period of about 15 minutes. The density increase is believed to be caused by the collapse of the ion cloud into the diamagnetic cavity created by the initial expansion. The plasma wave intensities observed during the entire event were quite low. In the diamagnetic cavity, electrostatic emissions were observed near the barium ion plasma frequency, and in another band at lower frequencies. A broadband burst of electrostatic noise was also observed at the boundary of the diamagnetic cavity. Except for electron plasma oscillations, no significant wave activity was observed outside of the diamagnetic cavity.

  14. Liquid-Phase Processing of Barium Titanate Thin Films

    NASA Astrophysics Data System (ADS)

    Harris, David Thomas

    Processing of thin films introduces strict limits on the thermal budget due to substrate stability and thermal expansion mismatch stresses. Barium titanate serves as a model system for the difficulty in producing high quality thin films because of sensitivity to stress, scale, and crystal quality. Thermal budget restriction leads to reduced crystal quality, density, and grain growth, depressing ferroelectric and nonlinear dielectric properties. Processing of barium titanate is typically performed at temperatures hundreds of degrees above compatibility with metalized substrates. In particular integration with silicon and other low thermal expansion substrates is desirable for reductions in costs and wider availability of technologies. In bulk metal and ceramic systems, sintering behavior has been encouraged by the addition of a liquid forming second phase, improving kinetics and promoting densification and grain growth at lower temperatures. This approach is also widespread in the multilayer ceramic capacitor industry. However only limited exploration of flux processing with refractory thin films has been performed despite offering improved dielectric properties for barium titanate films at lower temperatures. This dissertation explores physical vapor deposition of barium titanate thin films with addition of liquid forming fluxes. Flux systems studied include BaO-B2O3, Bi2O3-BaB2O 4, BaO-V2O5, CuO-BaO-B2O3, and BaO-B2O3 modified by Al, Si, V, and Li. Additions of BaO-B2O3 leads to densification and an increase in average grain size from 50 nm to over 300 nm after annealing at 900 °C. The ability to tune permittivity of the material improved from 20% to 70%. Development of high quality films enables engineering of ferroelectric phase stability using residual thermal expansion mismatch in polycrystalline films. The observed shifts to TC match thermodynamic calculations, expected strain from the thermal expansion coefficients, as well as x-ray diffract measurements

  15. Compact high power barium nitrite crystal-based Raman laser at 1197 nm for photoacoustic imaging of fat.

    PubMed

    Li, Rui; Slipchenko, Mikhail N; Wang, Pu; Cheng, Ji-Xin

    2013-04-01

    Photoacoustic imaging employing molecular overtone vibration as a contrast mechanism opens a new avenue for bond-selective imaging of deep tissues. Broad use of this modality is, however, hampered by the extremely low conversion efficiency of optical parametric oscillators at the overtone transition wavelengths. To overcome such a barrier, we demonstrate the construction and use of a compact, barium nitrite crystal-based Raman laser for photoacoustic imaging of C-H overtone vibrations. Using a 5-ns Nd∶YAG laser as the pumping source, up to 21.4 mJ pulse energy at 1197 nm was generated, corresponding to a conversion efficiency of 34.8%. Using the 1197 nm pulses, three-dimensional photoacoustic imaging of intramuscular fat was demonstrated. PMID:23536057

  16. Compact high power barium nitrite crystal-based Raman laser at 1197 nm for photoacoustic imaging of fat

    PubMed Central

    Li, Rui; Slipchenko, Mikhail N.; Wang, Pu

    2013-01-01

    Abstract. Photoacoustic imaging employing molecular overtone vibration as a contrast mechanism opens a new avenue for bond-selective imaging of deep tissues. Broad use of this modality is, however, hampered by the extremely low conversion efficiency of optical parametric oscillators at the overtone transition wavelengths. To overcome such a barrier, we demonstrate the construction and use of a compact, barium nitrite crystal-based Raman laser for photoacoustic imaging of C–H overtone vibrations. Using a 5-ns Nd∶YAG laser as the pumping source, up to 21.4 mJ pulse energy at 1197 nm was generated, corresponding to a conversion efficiency of 34.8%. Using the 1197 nm pulses, three-dimensional photoacoustic imaging of intramuscular fat was demonstrated. PMID:23536057

  17. Influence of atomic oxygen irradiation during deposition on crystallization of post-annealed barium zirconate thin films

    NASA Astrophysics Data System (ADS)

    Iguchi, Fumitada; Shibata, Yoshikazu; Miyazaki, Takamichi; Sata, Noriko; Yugami, Hiroo

    2014-11-01

    The role of atomic oxygen irradiation in the epitaxial crystallization of yttrium-doped barium zirconate thin films fabricated by pulsed laser deposition (PLD) was investigated. X-ray diffraction and transmission electron microscopy revealed that, for films deposited without irradiation, random nucleation and growth occurred below the onset temperature for continuous crystallization at the film-interlayer interface. In contrast, for films deposited with oxygen irradiation, random nucleation and growth was not detected at the temperature of continuous crystallization, which facilitates epitaxial crystallization in these films. This study suggests the combined low temperature deposition with atomic oxygen irradiation and post-annealing could control microstructure of solid-state electrochemical devices such as solid oxide fuel cells and solid-state lithium secondary batteries.

  18. Compact high power barium nitrite crystal-based Raman laser at 1197 nm for photoacoustic imaging of fat

    NASA Astrophysics Data System (ADS)

    Li, Rui; Slipchenko, Mikhail N.; Wang, Pu; Cheng, Ji-Xin

    2013-04-01

    Photoacoustic imaging employing molecular overtone vibration as a contrast mechanism opens a new avenue for bond-selective imaging of deep tissues. Broad use of this modality is, however, hampered by the extremely low conversion efficiency of optical parametric oscillators at the overtone transition wavelengths. To overcome such a barrier, we demonstrate the construction and use of a compact, barium nitrite crystal-based Raman laser for photoacoustic imaging of C-H overtone vibrations. Using a 5-ns Nd∶YAG laser as the pumping source, up to 21.4 mJ pulse energy at 1197 nm was generated, corresponding to a conversion efficiency of 34.8%. Using the 1197 nm pulses, three-dimensional photoacoustic imaging of intramuscular fat was demonstrated.

  19. Pediatric patient and staff dose measurements in barium meal fluoroscopic procedures

    NASA Astrophysics Data System (ADS)

    Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Porto, L. E.; Ledesma, J. A.; Nascimento, E. X.; Legnani, A.; Andrade, M. E. A.; Khoury, H. J.

    2015-11-01

    This study investigates patient and staff dose measurements in pediatric barium meal series fluoroscopic procedures. It aims to analyze radiographic techniques, measure the air kerma-area product (PKA), and estimate the staff's eye lens, thyroid and hands equivalent doses. The procedures of 41 patients were studied, and PKA values were calculated using LiF:Mg,Ti thermoluminescent dosimeters (TLDs) positioned at the center of the patient's upper chest. Furthermore, LiF:Mg,Cu,P TLDs were used to estimate the equivalent doses. The results showed a discrepancy in the radiographic techniques when compared to the European Commission recommendations. Half of the results of the analyzed literature presented lower PKA and dose reference level values than the present study. The staff's equivalent doses strongly depends on the distance from the beam. A 55-cm distance can be considered satisfactory. However, a distance decrease of ~20% leads to, at least, two times higher equivalent doses. For eye lenses this dose is significantly greater than the annual limit set by the International Commission on Radiological Protection. In addition, the occupational doses were found to be much higher than in the literature. Changing the used radiographic techniques to the ones recommended by the European Communities, it is expected to achieve lower PKA values ​​and occupational doses.

  20. X-ray Induced Luminescence Spectroscopy of Samarium Doped Barium Sulfate Prepared by Sintering Method

    NASA Astrophysics Data System (ADS)

    Kumeda, T.; Maeda, K.; Shirano, Y.; Fujiwara, K.; Sakai, K.; Ikari, T.

    2015-06-01

    X-ray induced luminescence (XL) properties of phosphor materials made of samarium doped barium sulfate have been investigated. The samples were prepared by sintering method heated at 900-1250 °C for 3 hours in air from the mixture of BaSO4 and Sm2O3. The concentration of Sm were prepared from 0.01-6 at.%. In as-prepared sample, the Sm3+ was detected by photoluminescence (PL). The PL intensity is maximum about 2 at.% with Sm, and then starts decreasing. The PL intensity showed concentration quenching. The XL observed Sm2+ and Sm3+ ions. The XL was shown from the sample sintered up to 1200 °C. The XL intensity increased with Sm concentration up to 1 at.%. The intensity was almost constant larger than 1 at.% Sm. These concentration dependences is different since the X-ray energy absorbed to the host material at once, and the energy transferred to both Sm3+ and Sm2+ ions. Sm doped BaSO4 is found a host for XL phosphor materials.

  1. Fabrication and characterization of cerium-doped barium titanate inverse opal by sol-gel method

    SciTech Connect

    Jin Yi; Zhu Yihua Yang Xiaoling; Li Chunzhong; Zhou Jinghong

    2007-01-15

    Cerium-doped barium titanate inverted opal was synthesized from barium acetate contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a polystyrene (PS) opal. This procedure involves infiltration of precursors into the interstices of the PS opal template followed by hydrolytic polycondensation of the precursors to amorphous barium titanate and removal of the PS opal by calcination. The morphologies of opal and inverse opal were characterized by scanning electron microscope (SEM). The pores were characterized by mercury intrusion porosimetry (MIP). X-ray photoelectron spectroscopy (XPS) investigation showed the doping structure of cerium, barium and titanium. And powder X-ray diffraction allows one to observe the influence of doping degree on the grain size. The lattice parameters, crystal size and lattice strain were calculated by the Rietveld refinement method. The synthesis of cerium-doped barium titanate inverted opals provides an opportunity to electrically and optically engineer the photonic band structure and the possibility of developing tunable three-dimensional photonic crystal devices. - Graphical abstract: Cerium-doped barium titanate inverted opal was synthesized from barium acetate acid contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a PS opal, which involves infiltration of precursors into the interstices of the PS opal template and removal of the PS opal by calcination.

  2. Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

    PubMed

    Liu, Yun; Zhang, Chuan-Jie; Zhao, Jin-Chao; Guo, Yi; Zhu, Ping; Wang, De-Yi

    2016-03-30

    A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed. PMID:26794953

  3. Magnetic properties of Ni substituted Y-type barium ferrite

    NASA Astrophysics Data System (ADS)

    Won, Mi Hee; Kim, Chul Sung

    2014-05-01

    Y-type barium hexaferrite is attractive material for various applications, such as high frequency antennas and RF devices, because of its interesting magnetic properties. Especially, Ni substituted Y- type hexaferrites have higher magnetic ordering temperature than other Y-type. We have investigated macroscopic and microscopic properties of Y-type barium hexaferrite. Ba2Co2-xNixFe12O22 (x = 0, 0.5, 1.0, 1.5, and 2.0) samples are prepared by solid-state reaction method and studied by X-ray diffraction (XRD), vibrating sample magnetometer, and Mössbauer spectroscopy, as well as a network analyzer for high frequency characteristics. The XRD pattern is analyzed by Rietveld refinement method and confirms the hexagonal structure with R-3m. The hysteresis curve shows ferrimagnetic behavior. Saturation magnetization (Ms) decreases with Ni contents. Ni2+, which preferentially occupies the octahedral site with up-spin sub-lattice, has smaller spin value S of 1 than Co2+ having S = 3/2. The zero-field-cooled (ZFC) measurement of Ba2Co1.5Ni0.5Fe12O22 shows that Curie and spin transition temperatures are found to be 718 K and 209 K, respectively. The Curie temperature TC is increased with Ni contents, while TS is decreased with Ni. The Mössbauer spectra were measured at various temperatures and fitted by using a least-squares method with six sextet of six Lorentzian lines for Fe sites, corresponding to the 3bVI, 6cIV*, 6cVI, 18hVI, 6cIV, and 3aIV sites at below TC. From Mössbauer measurements, we confirmed the spin state of Fe ion to be Fe3+ and obtained the isomer shift (δ), magnetic hyperfine field (Hhf), and the occupancy ratio of Fe ions at six sub-lattices. The complex permeability and permittivity are measured between 100 MHz and 4 GHz, suggesting that Y-type barium hexaferrite is promising for antenna applications in UHF band.

  4. Magnetic properties of Ni substituted Y-type barium ferrite

    SciTech Connect

    Won, Mi Hee; Kim, Chul Sung

    2014-05-07

    Y-type barium hexaferrite is attractive material for various applications, such as high frequency antennas and RF devices, because of its interesting magnetic properties. Especially, Ni substituted Y- type hexaferrites have higher magnetic ordering temperature than other Y-type. We have investigated macroscopic and microscopic properties of Y-type barium hexaferrite. Ba{sub 2}Co{sub 2−x}Ni{sub x}Fe{sub 12}O{sub 22} (x = 0, 0.5, 1.0, 1.5, and 2.0) samples are prepared by solid-state reaction method and studied by X-ray diffraction (XRD), vibrating sample magnetometer, and Mössbauer spectroscopy, as well as a network analyzer for high frequency characteristics. The XRD pattern is analyzed by Rietveld refinement method and confirms the hexagonal structure with R-3m. The hysteresis curve shows ferrimagnetic behavior. Saturation magnetization (M{sub s}) decreases with Ni contents. Ni{sup 2+}, which preferentially occupies the octahedral site with up-spin sub-lattice, has smaller spin value S of 1 than Co{sup 2+} having S = 3/2. The zero-field-cooled (ZFC) measurement of Ba{sub 2}Co{sub 1.5}Ni{sub 0.5}Fe{sub 12}O{sub 22} shows that Curie and spin transition temperatures are found to be 718 K and 209 K, respectively. The Curie temperature T{sub C} is increased with Ni contents, while T{sub S} is decreased with Ni. The Mössbauer spectra were measured at various temperatures and fitted by using a least-squares method with six sextet of six Lorentzian lines for Fe sites, corresponding to the 3b{sub VI}, 6c{sub IV}*, 6c{sub VI}, 18h{sub VI}, 6c{sub IV}, and 3a{sub IV} sites at below T{sub C}. From Mössbauer measurements, we confirmed the spin state of Fe ion to be Fe{sup 3+} and obtained the isomer shift (δ), magnetic hyperfine field (H{sub hf}), and the occupancy ratio of Fe ions at six sub-lattices. The complex permeability and permittivity are measured between 100 MHz and 4 GHz, suggesting that Y-type barium hexaferrite is promising for antenna

  5. Non-river flood barium signals in the skeletons of corals from coastal Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Sinclair, Daniel J.

    2005-09-01

    Two corals from coastal Queensland (Cow and Calf Islands, and Orpheus Island) have been analysed for a suite of trace elements by laser-ablation ICP-MS (LA-ICP-MS). Barium signals in these two corals are 'anomalous' in comparison with Ba behaviour seen in other near-shore corals from this region. The two corals display large sharp peaks in spring which do not correlate with markers of river discharge (Y/Ca and fluorescence). This Ba pattern contrasts with 'normal' behaviour—characterised here by the patterns previously published for two other coastal Queensland corals (King Reef and Pandora Reef), which display Ba peaks in summer associated with flooding of nearby rivers [1] [D.J. Sinclair, M.T. McCulloch, Corals record low mobile barium concentrations in the Burdekin River during the 1974 flood: evidence for limited Ba supply to rivers?, Palaeogeogr. Palaeoclimatol. Palaeoecol. 214 (1-2) (2004) 155-174]. Similarities are observed between the anomalous Ba in the Queensland corals and other published patterns of Ba behaviour in corals from South Africa and the Arabian Sea. This non-river flood Ba behaviour is characterized by large sharp spikes of Ba which are resistant to oxidative cleaning and form a continuous horizon within the coral. Curiously, not all corals from a region display anomalous Ba behaviour despite being in similar environments. The timing of anomalous Ba is consistent within a coral, but may vary from one location to the next. Anomalous Ba spikes are too large to be caused by Ba-rich upwelling, and no single environmental forcing function seems to be able to account for their timing. This combination of observations argues against an exogenous abiotic source for the anomalous Ba signal; instead, it may result from a biological event triggered by a combination of environmental parameters. Three hypotheses are presented, and critically tested against the observations: barite inclusion following phytoplankton blooms, decaying blooms of the blue

  6. CO2-based in-line phase contrast imaging of small intestine in mice

    PubMed Central

    Tang, Rongbiao; Li, Wei-Xia; Huang, Wei; Yan, Fuhua; Chai, Wei-Min; Yang, Guo-Yuan; Chen, Ke-Min

    2013-01-01

    The objective of this study was to explore the potential of CO2 single contrast in-line phase contrast imaging (PCI) for pre-clinical small intestine investigation. The absorption and phase contrast images of CO2 gas production were attained and compared. A further increase in image contrast was observed in PCI. Compared with CO2-based absorption contrast imaging (ACI), CO2-based PCI significantly enhanced the detection of mucosal microstructures, such as pits and folds. The CO2-based PCI could provide sufficient image contrast for clearly showing the intestinal mucosa in living mice without using barium. We concluded that CO2-based PCI might be a novel and promising imaging method for future studies of gastrointestinal disorders. PMID:23896957

  7. CO2-based in-line phase contrast imaging of small intestine in mice

    NASA Astrophysics Data System (ADS)

    Tang, Rongbiao; Li, Wei-Xia; Huang, Wei; Yan, Fuhua; Chai, Wei-Min; Yang, Guo-Yuan; Chen, Ke-Min

    2013-07-01

    The objective of this study was to explore the potential of CO2 single contrast in-line phase contrast imaging (PCI) for pre-clinical small intestine investigation. The absorption and phase contrast images of CO2 gas production were attained and compared. A further increase in image contrast was observed in PCI. Compared with CO2-based absorption contrast imaging (ACI), CO2-based PCI significantly enhanced the detection of mucosal microstructures, such as pits and folds. The CO2-based PCI could provide sufficient image contrast for clearly showing the intestinal mucosa in living mice without using barium. We concluded that CO2-based PCI might be a novel and promising imaging method for future studies of gastrointestinal disorders.

  8. Synthesis and characterization of rare earth doped barium fluoride nanoparticles and derivatized copper phthalocyanine nanoparticles

    NASA Astrophysics Data System (ADS)

    Bender, Christopher Mark

    1998-12-01

    Nanoparticles of neodymium doped barium fluoride (Nd:BaFsb2) were synthesized for use as the inorganic component of an optical amplifier composite. Microemulsions were used to maintain domain size in the nano-regime (˜100 nm), and decreasing the volume fraction of the aqueous content, while simultaneously increasing the volume fraction of the cosurfactant (methanol), gave a linear relationship between decreasing domain size and increasing volume fraction of alcohol. As Nd was added to the BaFsb2 host, direct incorporation was observed at low dopant levels (0-10 mol-%), a two-phase mixture was observed at intermediate dopant levels (10-50 mol-%), and a nearly amorphous product resulted with very high Nd-dopant levels (>50 mol-%). Fluorescence measurements of the solids showed that concentration quenching was delayed until unusually high levels, probably as a result of the lost crystallinity. Praseodymium and ytterbium codoped barium fluoride (Pr,Yb:BaFsb2) were also synthesized in microemulsions. Though as-prepared powders did not fluoresce, treatment with high temperatures (900sp°C) and dynamic vacuum resulted in products which would fluoresce at 1.3 mum. Lower temperature treatments (500-750sp°C) were used to decrease sintering, however this resulted in Ybsp{3+} products in which Ybsp{3+} fluorescence was quenched by exposure to air. Contamination due to water and hydroxide is believed to be the reason. Ethanolic microemulsions were used to make copper phthalocyanine (CuPc), which was modified with either zinc phthalocyanine (ZnPc) or copper phthalcyaninesulfonic acid by means of a flow system. The sulfonic acid derivative was lost upon aqueous washing. The zinc derivatized product gave a dispersion in n-hexylamine, which was stable for seven days. The mole ratio of Cu:Zn was 1:1 for the solids dispersed in n-hexylamine, and was 6:1 for the solids that were not dispersed. Because underivatized CuPc formed by the same method did not result in a dispersed product

  9. An XPS study of the optimum loading of barium on high-silica MFI zeolite

    NASA Astrophysics Data System (ADS)

    Mohamed, M. H.; Abdillahi, M. M.; Abbas, N. M.; Siddiqui, A. B.

    1995-12-01

    X-ray photoelectron spectroscopy (XPS) has been applied to the characterization of barium-impregnated MFI high-silica zeolites which are used for the conversion of methanol to light alkenes. X-ray photoelectron spectroscopy provided information about the degree of the dispersion of the various barium loadings on the silicalite structure, and this information helped in elucidating the observed relationship between the activity/selectivity of the catalysts and the barium loading. The XPS results also helped in predicting that the performance of the catalyst would be optimized at 4 wt% Ba loading which was found to agree with the catalytic conversion of methanol to light alkenes.

  10. [Contrast sensitivity in glaucoma].

    PubMed

    Bartos, D

    1989-05-01

    Author reports on results of the contrast sensitivity examinations using the Cambridge low-contrast lattice test supplied by Clement Clarke International LTD, in patients with open-angle glaucoma and ocular hypertension. In glaucoma patients there was observed statistically significant decrease of the contrast sensitivity. In patients with ocular hypertension decrease of the contrast sensitivity was in patients affected by corresponding changes of the visual field and of the optical disc. The main advantages of the Cambridge low-contrast lattice test were simplicity, rapidity and precision of its performance. PMID:2743444

  11. Photorefractive properties of cobalt-doped strontium barium niobate crystals

    SciTech Connect

    Bogodaev, N V; Ivleva, Lyudmila I; Lykov, P A; Polozkov, N M; Osiko, Vyacheslav V

    1999-05-31

    The two-wave interaction (at {lambda} = 488 nm) in strontium barium niobate crystals doped with cobalt ions (Co:SBN) was studied. The experimental dependences of the gain coefficient on the grating period and of the grating response time on the writing beam intensity were used to calculate the Debye screening length, the diffusion length, the dark conductivity, and the effective concentration of carrier traps for a series of Co:SBN crystals with different dopant concentrations. The crystals were shown to have high coupling coefficients ({Gamma} = 33 cm{sup -1}) and short optical response times ({tau} = 140 ms for I = 1 W cm{sup -2} ). This, in combination with a high photorefractive sensitivity (S = 39 cm{sup 2} J{sup -1} ), determines the efficiency of their use in the storage of optical information and in laser phase conjugation. (nonlinear optical phenomena)

  12. Synthesis, microstructure and dielectric properties of zirconium doped barium titanate

    NASA Astrophysics Data System (ADS)

    Kumar, Rohtash; Asokan, K.; Patnaik, S.; Birajdar, Balaji

    2016-05-01

    We report on synthesis, microstructural and relaxor ferroelectric properties of Zirconium(Zr) doped Barium Titanate (BT) samples with general formula Ba(Ti1-xZrx)O3 (x=0.20, 0.35). These lead-free ceramics were prepared by solid state reaction route. The phase transition behavior and temperature dependent dielectric properties and composition dependent ferroelectric properties were investigated. XRD analysis at room temperature confirms phase purity of the samples. SEM observations revealed retarded grain growth with increasing Zr mole fraction. Dielectric properties of BZT ceramics is influenced significantly by small addition of Zr mole fraction. With increasing Zr mole fraction, dielectric constant decreases while FWHM and frequency dispersion increases. Polarization vs electric field hysteresis measurements reveal ferroelectric relaxor phase at room temperature. The advantages of such substitution maneuvering towards optimizing ferroelectric properties of BaTiO3 are discussed.

  13. Laser irradiation in Nd3+ doped strontium barium niobate glass

    NASA Astrophysics Data System (ADS)

    Haro-González, P.; Martín, I. R.; Arbelo-Jorge, E.; González-Pérez, S.; Cáceres, J. M.; Núñez, P.

    2008-07-01

    A local nanocrystalline formation in a neodymium doped strontium barium niobate (SBN) glass has been obtained under argon laser irradiation. The intense emission around 880 nm, originated from the F43/2 (F45/2) thermalized level when the glass structure changes to a glass ceramic structure due to the irradiation of the laser beam, has been studied. The intensities and lifetimes change from this level inside and outside the irradiated area made by the laser excitation. They have been analyzed and demonstrated that the desvitrification process has been successfully achieved. These results confirm that nanocrystals of SBN have been created by the laser action confirming that the transition from glass to glass ceramic has been completed. These results are in agreement with the emission properties of nanocrystals of the bulk glass ceramic sample. The present study also suggests that the SBN nanocrystal has a potential application as temperature detector.

  14. The Performance of Barium Sulfate Nanoparticles/polypropylene Hybrid Multifilament

    NASA Astrophysics Data System (ADS)

    Li, Ying; Wang, Xuanjun; Mu, Xiaoxi; Zhang, Shujuan

    2012-01-01

    Nanosize barium sulfate (BaSO4) particles prepared with dodecyl benzene sulfonic acid (DBSA) in ethanol-water reaction system are used to prepare BaSO4/polypropylene (PP) nanocomposites by melt mixing method. It is then made into hybrid fibers by melt spinning and subsequent drawing with different ratios. The hybrid fibers are characterized by rheology, morphology, thermal stability and mechanical properties, respectively. The results indicate that the DBSA-modified BaSO4 can improve the spinnability of BaSO4/PP hybrid multifilament even at high BaSO4 nanoparticles concentration. DBSA can be used as compatibilizer to enhance the interface interaction of BaSO4/PP nanocomposites, because DBSA contains both hydrophobicity long alkyl chain and hydrophilic sulfonic group. Therefore, it can improve the performances of BaSO4/PP hybrid multifilament.

  15. A buffer gas cooled beam of barium monohydride

    NASA Astrophysics Data System (ADS)

    Iwata, Geoffrey; Tarallo, Marco; Zelevinsky, Tanya

    2016-05-01

    Significant advances in direct laser cooling of diatomic molecules have opened up a wide array of molecular species to precision studies spanning many-body physics, quantum collisions and ultracold dissociation. We present a cryogenic beam source of barium monohydride (BaH), and study laser ablation of solid precursor targets as well as helium buffer gas cooling dynamics. Additionally, we cover progress towards a molecular magneto-optical trap, with spectroscopic studies of relevant cooling transitions in the B2 Σ <--X2 Σ manifold in laser ablated molecules, including resolution of hyperfine structure and precision measurements of the vibrational Frank-Condon factors. Finally, we examine the feasibility of photo dissociation of trapped BaH molecules to yield optically accessible samples of ultracold hydrogen.

  16. Study on a flexoelectric microphone using barium strontium titanate

    NASA Astrophysics Data System (ADS)

    Kwon, S. R.; Huang, W. B.; Zhang, S. J.; Yuan, F. G.; Jiang, X. N.

    2016-04-01

    In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba0.65Sr0.35TiO3) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications.

  17. Barium depletion study on impregnated cathodes and lifetime prediction

    NASA Astrophysics Data System (ADS)

    Roquais, J. M.; Poret, F.; le Doze, R.; Ricaud, J. L.; Monterrin, A.; Steinbrunn, A.

    2003-06-01

    In the thermionic cathodes used in cathode ray-tubes (CRTs), barium is the key element for the electronic emission. In the case of the dispenser cathodes made of a porous tungsten pellet impregnated with Ba, Ca aluminates, the evaporation of Ba determines the cathode lifetime with respect to emission performance in the CRT. The Ba evaporation results in progressive depletion of the impregnating material inside the pellet. In the present work, the Ba depletion with time has been extensively characterized over a large range of cathode temperature. Calculations using the depletion data allowed modeling of the depletion as a function of key parameters. The link between measured depletion and emission in tubes has been established, from which an end-of-life criterion was deduced. Taking modeling into account, predicting accelerated life-tests were performed using high-density maximum emission current (MIK).

  18. Influence of Barium Hexaferrite on Magnetic Properties of Hydroxyapatite Ceramics.

    PubMed

    Jarupoom, P; Jaita, P

    2015-11-01

    Hydroxyapatite (HA) powders was derived from natural bovine bone by sequence of thermal processes. The barium hexaferrite (BF) find magnetic powders were added into HA powders in ratio of 1-3 vol.%. The HA-BF ceramics were prepared by a solid state reaction method and sintered at 1250 degrees C for 2 h. Effects of BF additive on structural, physical and magnetic properties of HA ceramics were investigated. X-ray diffraction revealed that all HA-BF samples showed a main phase of high purity hydroxyapatite [Ca10(PO4)6(OH)2] with calcium and phosphate molar ratio of 1.67. The addition of BF into HA inhibited grain growth and caused an improvement of mechanical properties. The M-H hysteresis loops also showed an improvement in magnetic behavior for higher content of BF. Moreover, in vitro bioactivity test indicated that the 2-3 vol.% sample may be suitable for biological applications. PMID:26726671

  19. Gamma radiation induced darkening in barium gallo-germanate glass.

    PubMed

    Chen, Xiaodong; Heng, Xiaobo; Tang, Guowu; Zhu, Tingting; Sun, Min; Shan, Xiujie; Wen, Xin; Guo, Jingyuan; Qian, Qi; Yang, Zhongmin

    2016-05-01

    Barium gallo-germanate (BGG) glass is an important glass matrix material used for mid-infrared transmission and mid-infrared fiber laser. In this study, we investigated the γ-ray irradiation induced darkening effect of BGG glass. Optical transmittance spectra, electron paramagnetic resonance (EPR) and thermoluminescence (TL) spectra were employed to investigate the γ-ray irradiation induced defects. Two kinds of Ge-related defects in the irradiated BGG glass, named Ge-related non-bridging oxygen hole center (Ge-NBOHC) and Ge-related electron centers (GEC), were verified. In addition, the absorption bands of the two defects have been separated and the peak absorptivity of Ge-NBOHC and GEC defects is at 375 nm and 315 nm, respectively. PMID:27137531

  20. Synthesis and optical study of barium magnesium aluminate blue phosphors

    NASA Astrophysics Data System (ADS)

    Jeet, Suninder; Sharma, Manoj; Pandey, O. P.

    2015-05-01

    Europium doped barium magnesium aluminate (BaMgAl10O17:Eu2+) phosphor was prepared via solution combustion method at 550°C using urea as a fuel. Morphological and optical properties of the prepared sample was studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy (PL). XRD result showed the formation of pure phase BaMgAl10O17(JCPDS 26-0163) along with an additional phase BaAl2O4(JCPDS 01-082-1350). TEM image indicated the formation of faceted particles with average particle size 40 nm. From PL spectra, a broad emission band obtained at about 450 nm attributes to 4f6 5d → 4f7 transition of Eu2+ which lies in the blue region of the visible spectrum.

  1. Studies on immobilization of thorium in barium borosilicate glass

    NASA Astrophysics Data System (ADS)

    Mishra, R. K.; Sengupta, Pranesh; Kaushik, C. P.; Tyagi, A. K.; Kale, G. B.; Raj, Kanwar

    2007-02-01

    The barium borosilicate glass (BBS) matrix has shown considerable solubility of ThO2 at 1000 °C. As seen by X-ray diffractometry (XRD) and Electron probe micro analysis (EPMA) up to 15.86 wt% of ThO2 could be dissolved in this matrix. The homogeneity of thoria loaded glass was convincingly ascertained by EPMA. Attempts to load more than 16 wt% ThO2 led to the phase separation of crystalline phases identified as major phase of ThO2 and minor percentage of ThSiO4 phase with altogether different morphologies, as seen by XRD. Interestingly, the back scattered images of thorite crystals point towards the presence of chemical zoning. The results being reported in this paper are of interest especially with respect to immobilization of other actinides in borosilicate glass matrix.

  2. Small polarons and point defects in barium cerate

    NASA Astrophysics Data System (ADS)

    Swift, Michael; Janotti, Anderson; Van de Walle, Chris G.

    2015-12-01

    Barium cerate (BaCeO3) is a well-known ionic conductor of both hydrogen and oxygen. In applications, it is frequently doped (for instance with Y) to increase stability and promote diffusion. However, the effects of doping and native defects are not fully understood. Computational studies have been stymied by the nature of the conduction band, which is made up of cerium 4 f states. These states present a challenge to ab initio techniques based on density functional theory within the standard approximations for exchange and correlation. Using a hybrid functional, we investigate the effects of hydrogen impurities and native defects on the electrical and optical properties of BaCeO3. We discuss the tendency of excess electrons or holes to localize in the form of small polarons. We also explore the interactions of polarons with hydrogen impurities and oxygen vacancies, and their impact on luminescence properties.

  3. Ultrasonic de-agglomeration of barium titanate powder.

    PubMed

    Marković, S; Mitrić, M; Starcević, G; Uskoković, D

    2008-01-01

    BaTiO3 (BT) powder, with average particle size of 1.4 microm, was synthesized by solid-state reaction. A high-intensity ultrasound irradiation (ultrasonication) was used to de-agglomerate micro-sized powder to nano-sized one. The crystal structure, crystallite size, morphology, particle size, particle size distribution, and specific surface area of the BT powder de-agglomerated for different ultrasonication times (0, 10, 60, and 180 min) were determined. It was found that the particles size of the BT powder was influenced by ultrasonic treatment, while its tetragonal structure was maintained. Therefore, ultrasonic irradiation can be proposed as an environmental-friendly, economical, and effective tool for the de-agglomeration of barium titanate powders. PMID:17845864

  4. Synthesis and optical study of barium magnesium aluminate blue phosphors

    SciTech Connect

    Jeet, Suninder Pandey, O. P.; Sharma, Manoj

    2015-05-15

    Europium doped barium magnesium aluminate (BaMgAl{sub 10}O{sub 17}:Eu{sup 2+}) phosphor was prepared via solution combustion method at 550°C using urea as a fuel. Morphological and optical properties of the prepared sample was studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy (PL). XRD result showed the formation of pure phase BaMgAl{sub 10}O{sub 17}(JCPDS 26-0163) along with an additional phase BaAl{sub 2}O{sub 4}(JCPDS 01-082-1350). TEM image indicated the formation of faceted particles with average particle size 40 nm. From PL spectra, a broad emission band obtained at about 450 nm attributes to 4f{sup 6} 5d → 4f{sup 7} transition of Eu{sup 2+} which lies in the blue region of the visible spectrum.

  5. Nonlinear optical properties of calcium barium niobate epitaxial thin films.

    PubMed

    Bancelin, Stéphane; Vigne, Sébastien; Hossain, Nadir; Chaker, Mohammed; Légaré, François

    2016-07-25

    We investigate the potential of epitaxial calcium barium niobate (CBN) thin film grown by pulsed laser deposition for optical frequency conversion. Using second harmonic generation (SHG), we analyze the polarization response of the generated signal to determine the ratios d15 / d32 and d33 / d32 of the three independent components of the second-order nonlinear susceptibility tensor in CBN thin film. In addition, a detailed comparison to the signal intensity obtained in a y-cut quartz allows us to measure the absolute value of these components in CBN thin film: d15 = 5 ± 2 pm / V, d32 = 3.1 ± 0.6 pm / V and d33 = 9 ± 2 pm / V. PMID:27464195

  6. Dynamics of the CRRES barium releases in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Mende, S. B.; Geller, S. P.; Miller, M.; Hoffman, R. A.; Wygant, J. R.; Pongratz, M.; Meredith, N. P.; Anderson, R. R.

    1994-01-01

    The Combined Release and Radiation Effects Satellite (CRRES) G-2, G-3, and G-4 ionized and neutral barium cloud positions are triangulated from ground-based optical data. From the time history of the ionized cloud motion perpendicular to the magnetic field, the late time coupling of the ionized cloud with the collisionless ambient plasma in the magnetosphere is investigated for each of the releases. The coupling of the ionized clouds with the ambient medium is quantitatively consistent with predictions from theory in that the coupling time increases with increasing distance from the Earth. Quantitative comparison with simple theory for the couping time also yields reasonable agreement. Other effects not predicted by the theory are discussed in the context of the observations.

  7. Pulsating aurora induced by upper atmospheric barium releases

    NASA Technical Reports Server (NTRS)

    Deehr, C.; Romick, G.

    1977-01-01

    The paper reports the apparent generation of pulsating aurora by explosive releases of barium vapor near 250 km altitude. This effect occurred only when the explosions were in the path of precipitating electrons associated with the visible aurora. Each explosive charge was a standard 1.5 kg thermite mixture of Ba and CuO with an excess of Ba metal which was vaporized and dispersed by the thermite explosion. Traces of Sr, Na, and Li were added to some of the charges, and monitoring was achieved by ground-based spectrophotometric observations. On March 28, 1976, an increase in emission at 5577 A and at 4278 A was observed in association with the first two bursts, these emissions pulsating with roughly a 10 sec period for approximately 60 to 100 sec after the burst.

  8. Dielectric behavior of barium modified strontium bismuth titanate ceramic

    SciTech Connect

    Nayak, P.; Badapanda, T.; Anwar, S.; Panigrahi, S.

    2014-04-24

    Barium Modified Strontium Bismuth Titanate(SBT) ceramic with general formula Sr1−xBaxBi4Ti4O15 is prepared by solid state reaction route. The structural analysis of the ceramics was done by X-ray diffraction technique. The X-ray patterns show that all the compositions are of single phase with orthorhombic structure. The temperature dependent dielectric behavior shows that the transition temperature decreases with Ba content but the maximum dielectric constant increases. The decreases of the transition with increase in Ba{sup 2+} ion, may be due to the decrease of orthorhombicity by the incorporation of Ba{sup 2+} ion in SBT lattice.

  9. Structural and magnetic properties of barium-gadolinium hexaferrites

    NASA Astrophysics Data System (ADS)

    Litsardakis, G.; Manolakis, I.; Serletis, C.; Efthimiadis, K. G.

    A series of Gd-substituted M-type barium hexaferrites has been prepared by the ceramic route, according to the formula (Ba 1-xGd x)O·5.25Fe 2O 3 ( x=0-0.30). XRD analysis revealed that all the samples present primarily an M-type structure. Samples x=0 and x=0.05 are single-phase. Hematite (Fe 2O 3) and GdFeO 3 were detected in the remaining samples. Coercivity ( Hc) shows remarkably high values, ˜293 kA/m for x=0.20 and 0.30 with a maximum of 322 kA/m for x=0.25. Specific saturation magnetization ( σsat) of the samples presents a small increase up to x=0.10. The microstructure examination indicates that Gd may act as a grain growth inhibitor.

  10. Barium titanate nanocomposite capacitor FY09 year end report.

    SciTech Connect

    Stevens, Tyler E.; DiAntonio, Christopher Brian; Yang, Pin; Chavez, Tom P.; Winter, Michael R.; Monson, Todd C.; Roesler, Alexander William; Fellows, Benjamin D.

    2009-11-01

    This late start RTBF project started the development of barium titanate (BTO)/glass nanocomposite capacitors for future and emerging energy storage applications. The long term goal of this work is to decrease the size, weight, and cost of ceramic capacitors while increasing their reliability. Ceramic-based nanocomposites have the potential to yield materials with enhanced permittivity, breakdown strength (BDS), and reduced strain, which can increase the energy density of capacitors and increase their shot life. Composites of BTO in glass will limit grain growth during device fabrication (preserving nanoparticle grain size and enhanced properties), resulting in devices with improved density, permittivity, BDS, and shot life. BTO will eliminate the issues associated with Pb toxicity and volatility as well as the variation in energy storage vs. temperature of PZT based devices. During the last six months of FY09 this work focused on developing syntheses for BTO nanoparticles and firing profiles for sintering BTO/glass composite capacitors.

  11. Brillouin function characteristics for La-Co substituted barium hexaferrites

    SciTech Connect

    Wu, Chuanjian E-mail: ksun@uestc.edu.cn; Yu, Zhong; Sun, Ke E-mail: ksun@uestc.edu.cn; Guo, Rongdi; Jiang, Xiaona; Lan, Zhongwen; Yang, Yan

    2015-09-14

    La-Co substituted barium hexaferrites with the chemical formula of Ba{sub 1−x}La{sub x}Fe{sub 12−x}Co{sub x}O{sub 19} (x = 0.0, 0.1, 0.3, and 0.5), prepared by a conventional ceramic method, were systematically investigated by Raman spectra, X-ray photoelectron spectroscopy, Rietveld refinement of X-ray diffraction patterns, and vibrating sample magnetometer. The result manifests that all the compounds are crystallized in magnetoplumbite hexagonal structure. Trivalent cobalt ions prevailingly occupy the 2a, 4f{sub 1}, and 12k sites. According to Néel model of collinear-spin ferrimagnetism, the molecular-field coefficients ω{sub bf2}, ω{sub kf1}, ω{sub af1}, ω{sub kf2}, and ω{sub bk} of La-Co substituted barium hexaferrites have been calculated using the nonlinear fitting method, and the magnetic moment of five sublattices (2a, 2b, 4f{sub 1}, 4f{sub 2}, and 12k) versus temperature T has been also investigated. The fitting results are coincided well with the experimental data. Moreover, with the increase of La-Co substitution amount x, the molecular-field coefficients ω{sub bf2} and ω{sub af1} decrease constantly, while the molecular-field coefficients ω{sub kf1}, ω{sub kf2}, and ω{sub bk} show a slight change.

  12. Raman Gain Coefficient of Barium Nitrate Measured for the Spectral Region of TI:SAPPHIRE Laser

    NASA Astrophysics Data System (ADS)

    Lisinetskii, V. A.; Mishkel', I. I.; Chulkov, R. V.; Grabtchikov, A. S.; Apanasevich, P. A.; Eichler, H.-J.; Orlovich, V. A.

    We report the measurements of the Raman gain coefficient for a barium nitrate crystal in the spectral region of a Ti:Sapphire laser using Raman amplification. The experimentally-obtained data are well described by the known empirical formula.

  13. The value of the preoperative barium-enema examination in the assessment of pelvic masses

    SciTech Connect

    Gedgaudas, R.K.; Kelvin, F.M.; Thompson, W.M.; Rice, R.P.

    1983-03-01

    The value of the barium-enema examination in the assessment of pelvic masses was studied in 44 patients. Findings from those barium-enema examinations and from pathological specimens from 37 patients who had malignant tumors and seven patients who had endometriosis were retrospectively analyzed to determine if the barium-enema examination is useful in differentiating extrinsic lesions with and without invasion of the colon. None of the 12 patients who had extrinsic lesions had any of the criteria that indicated bowel-wall invasion. These criteria included fixation and serrations of the bowel wall in all patients with invasion, and ulceration and fistulizaton in those patients who had complete transmural invasion. In patients with pelvic masses, the preoperative barium-enema examination may be useful to the surgeon in planning surgery and in preparing the patient for the possibility of partial colectomy or colostomy.

  14. Numberical simulation of the effects of radially injected barium plasma in the ionosphere

    NASA Technical Reports Server (NTRS)

    Swift, D. W.

    1985-01-01

    The morphology of the ion cloud in the radial shaped charge barium injection was studied. The shape of the ion cloud that remains after the explosive products and neutral barium clears away was examined. The ion cloud which has the configuration of a rimless wagon wheel is shown. The major features are the 2.5 km radius black hole in the center of the cloud, the surrounding ring of barium ion and the spokes of barium ionization radiating away from the center. The cloud shows no evolution after it emerges from the neutral debris and it is concluded that it is formed within 5 seconds of the event. A numerical model is used to calculate the motion of ions and electrons subject to the electrostatic and lorenz forces.

  15. Expulsion of Barium and Methane at Mud Volcanoes in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Castellini, D. G.; Dickens, G. R.; Snyder, G. T.; Gilhooly, W. P.; Ruppel, C. D.

    2003-12-01

    Submarine mud volcanoes and cold-seeps along continental margins transfer methane from gas-charged marine sediments to the water column. Such methane venting is dynamic and may provide an important and variable supply of carbon to the ocean and atmosphere through time. Barite mounds and chimneys have been found around some modern mud volcanoes and seeps, and similar structures can be identified in the geological record (e.g., bedded barite deposits). These observations suggest that expelled methane-rich fluids are greatly enriched in dissolved barium. However, there are very few analyses of barium concentrations in these systems. Here, we examine the dissolved barium of pore fluids from a series of shallow piston cores across two submarine mud volcanoes in the Gulf of Mexico. Dissolved barium concentrations at 1.5 m below the seafloor at the Garden Bank volcano range from 18200 μ M at the center of the feature to 0.56 μ M on its flanks approximately 1 km away. Similarly, dissolved barium concentrations at the Mississippi Canyon volcano range from 15600 μ M to 0.50 μ M. Thus, the concentrations in the cores of the mud volcanoes are nominally 5 orders of magnitude greater than in mean ocean water ( ˜0.1 μ M). Anaerobic oxidation of upward flowing methane consumes sulfate, which leads to the dissolution of barite and release of barium to pore fluids. Because this mechanism alone cannot explain the extreme concentrations in the mud volcanoes, a deep source of barium may exist in the Gulf of Mexico strata. Our current work is focused on quantifying the fluxes and sedimentary fate of expelled barium at these locations. However, even if a large fraction of the barium precipitates adjacent to the sites of methane venting, fluid expulsion at mud volcanoes must significantly impact the barium cycle in the Gulf of Mexico. Conceivably, submarine mud volcanoes and cold-seeps along continental margins are a major source of barium to the deep ocean, a concept that has

  16. Contrast Intravasation During Hysterosalpingography

    PubMed Central

    Bhoil, Rohit; Sood, Dinesh; Sharma, Tanupriya; Sood, Shilpa; Sharma, Jiten; Kumar, Nitesh; Ahluwalia, Ajay; Parekh, Dipen; Mistry, Kewal A.; Sood, Saurav

    2016-01-01

    Summary Hysterosalpingography is an imaging method to evaluate the endometrial and uterine morphology and fallopian tube patency. Contrast intravasation implies backflow of injected contrast into the adjoining vessels mostly the veins and may be related to factors altering endometrial vascularity and permeability. Radiologists and gynaecologists should be well acquainted with the technique of hysterosalpingography, its interpretation, and intravasation of contrast agents for safer procedure and to minimize the associated complications. PMID:27279925

  17. Generation of sub-100-fs Stokes pulses upon SRS in a barium nitrate crystal

    SciTech Connect

    Konyashchenko, Aleksandr V; Losev, Leonid L; Tenyakov, S Yu

    2010-10-15

    72-fs pulses are generated at the first Stokes component frequency upon stimulated Raman scattering in a barium nitrate crystal for the radiation of the Ti{sup 3+}:Al{sub 2}O{sub 3} laser with the pulse duration of 50 fs. The energy efficiency of conversion is 20%. The barium nitrate crystal was optically pumped by two consecutive orthogonally polarised chirped pulses with the following time compression of the Stokes radiation pulse. (nonlinear optical phenomena)

  18. Role of Barium Swallow in Diagnosing Clinically Significant Anastomotic Leak following Esophagectomy

    PubMed Central

    Roh, Simon; Iannettoni, Mark D.; Keech, John C.; Bashir, Mohammad; Gruber, Peter J.; Parekh, Kalpaj R.

    2016-01-01

    Background Barium swallow is performed following esophagectomy to evaluate the anastomosis for detection of leaks and to assess the emptying of the gastric conduit. The aim of this study was to evaluate the reliability of the barium swallow study in diagnosing anastomotic leaks following esophagectomy. Methods Patients who underwent esophagectomy from January 2000 to December 2013 at our institution were investigated. Barium swallow was routinely done between days 5–7 to detect a leak. These results were compared to clinically determined leaks (defined by neck wound infection requiring jejunal feeds and or parenteral nutrition) during the postoperative period. The sensitivity and specificity of barium swallow in diagnosing clinically significant anastomotic leaks was determined. Results A total of 395 esophagectomies were performed (mean age, 62.2 years). The indications for the esophagectomy were as follows: malignancy (n=320), high-grade dysplasia (n=14), perforation (n=27), benign stricture (n=7), achalasia (n=16), and other (n=11). A variety of techniques were used including transhiatal (n=351), McKeown (n=35), and Ivor Lewis (n=9) esophagectomies. Operative mortality was 2.8% (n=11). Three hundred and sixty-eight patients (93%) underwent barium swallow study after esophagectomy. Clinically significant anastomotic leak was identified in 36 patients (9.8%). Barium swallow was able to detect only 13/36 clinically significant leaks. The sensitivity of the swallow in diagnosing a leak was 36% and specificity was 97%. The positive and negative predictive values of barium swallow study in detecting leaks were 59% and 93%, respectively. Conclusion Barium swallow is an insensitive but specific test for detecting leaks at the cervical anastomotic site after esophagectomy. PMID:27066433

  19. Barium isotopes in Allende meteorite - Evidence against an extinct superheavy element

    NASA Technical Reports Server (NTRS)

    Lewis, R. S.; Anders, E.; Shimamura, T.; Lugmair, G. W.

    1983-01-01

    Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10 to the 11th atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis.

  20. Comparison of the reflectance characteristics of polytetrafluoroethylene and barium sulfate paints

    NASA Technical Reports Server (NTRS)

    Butner, C. L.; Schutt, J. B.; Shai, M. C.

    1984-01-01

    Preliminary results are presented of the directional reflectance measurements taken on two tetrafluorethylene (TFE) paints formulated with silicone binders. Both paints are found to be more Lambertian than barium sulfate paint and pressed powder, although the pigment to binder ratios for barium sulfate and TFE paints are about 133 and 3.3 to 1, respectively. The TFE paints exhibit total visible reflectances above 90 percent and offer surfaces that are not significantly affected by water.

  1. Calculations of energy levels and lifetimes of low-lying states of barium and radium

    SciTech Connect

    Dzuba, V. A.; Ginges, J. S. M.

    2006-03-15

    We use the configuration-interaction method and many-body perturbation theory to perform accurate calculations of energy levels, transition amplitudes, and lifetimes of low-lying states of barium and radium. Calculations for radium are needed for the planning of measurements of parity- and time-invariance-violating effects which are strongly enhanced in this atom. Calculations for barium are used to control the accuracy of the calculations.

  2. Comparison of Calcium and Barium Microcapsules as Scaffolds in the Development of Artificial Dermal Papillae.

    PubMed

    Liu, Yang; Lin, Changmin; Zeng, Yang; Li, Haihong; Cai, Bozhi; Huang, Keng; Yuan, Yanping; Li, Yu

    2016-01-01

    This study aimed to develop and evaluate barium and calcium microcapsules as candidates for scaffolding in artificial dermal papilla. Dermal papilla cells (DPCs) were isolated and cultured by one-step collagenase treatment. The DPC-Ba and DPC-Ca microcapsules were prepared by using a specially designed, high-voltage, electric-field droplet generator. Selected microcapsules were assessed for long-term inductive properties with xenotransplantation into Sprague-Dawley rat ears. Both barium and calcium microcapsules maintained xenogenic dermal papilla cells in an immunoisolated environment and induced the formation of hair follicle structures. Calcium microcapsules showed better biocompatibility, permeability, and cell viability in comparison with barium microcapsules. Before 18 weeks, calcium microcapsules gathered together, with no substantial immune response. After 32 weeks, some microcapsules were near inflammatory cells and wrapped with fiber. A few large hair follicles were found. Control samples showed no marked changes at the implantation site. Barium microcapsules were superior to calcium microcapsules in structural and mechanical stability. The cells encapsulated in hydrogel barium microcapsules exhibited higher short-term viability. This study established a model to culture DPCs in 3D culture conditions. Barium microcapsules may be useful in short-term transplantation study. Calcium microcapsules may provide an effective scaffold for the development of artificial dermal papilla. PMID:27123456

  3. Comparison of Calcium and Barium Microcapsules as Scaffolds in the Development of Artificial Dermal Papillae

    PubMed Central

    Liu, Yang; Lin, Changmin; Zeng, Yang; Li, Haihong; Cai, Bozhi; Huang, Keng; Yuan, Yanping; Li, Yu

    2016-01-01

    This study aimed to develop and evaluate barium and calcium microcapsules as candidates for scaffolding in artificial dermal papilla. Dermal papilla cells (DPCs) were isolated and cultured by one-step collagenase treatment. The DPC-Ba and DPC-Ca microcapsules were prepared by using a specially designed, high-voltage, electric-field droplet generator. Selected microcapsules were assessed for long-term inductive properties with xenotransplantation into Sprague-Dawley rat ears. Both barium and calcium microcapsules maintained xenogenic dermal papilla cells in an immunoisolated environment and induced the formation of hair follicle structures. Calcium microcapsules showed better biocompatibility, permeability, and cell viability in comparison with barium microcapsules. Before 18 weeks, calcium microcapsules gathered together, with no substantial immune response. After 32 weeks, some microcapsules were near inflammatory cells and wrapped with fiber. A few large hair follicles were found. Control samples showed no marked changes at the implantation site. Barium microcapsules were superior to calcium microcapsules in structural and mechanical stability. The cells encapsulated in hydrogel barium microcapsules exhibited higher short-term viability. This study established a model to culture DPCs in 3D culture conditions. Barium microcapsules may be useful in short-term transplantation study. Calcium microcapsules may provide an effective scaffold for the development of artificial dermal papilla. PMID:27123456

  4. The tube esophagram: a technique for obtaining a detailed double-contrast examination of the esophagus.

    PubMed

    Levine, M S; Kressel, H Y; Laufer, I; Herlinger, H; Goren, R

    1984-02-01

    Although double-contrast esophagography is capable of delineating fine surface morphologic detail in the esophagus, it is not possible to obtain an optimal examination on all patients. Tube esophagography is a complementary technique that can provide a more detailed double-contrast examination of the esophagus. This procedure was performed on 45 patients in whom the routine double-contrast study was inconclusive. The tube esophagram contributed significantly to the radiologic evaluation in 33 cases, providing additional information in 23 and actually altering the final radiologic diagnosis in 10. The tube esophagram was particularly useful in depicting the distal esophagus when the initial double-contrast study was suboptimal due to inadequate distension and/or barium pooling that obscured mucosal detail in this region. The tube esophagram is a valuable adjunctive procedure that can lead to a more definitive radiologic diagnosis when the routine double-contrast examination is inconclusive. PMID:6607593

  5. Toward Critical Contrastive Rhetoric

    ERIC Educational Resources Information Center

    Kubota, Ryuko; Lehner, Al

    2004-01-01

    A traditional approach to contrastive rhetoric has emphasized cultural difference in rhetorical patterns among various languages. Despite its laudable pedagogical intentions to raise teachers' and students' cultural and rhetorical awareness in second language writing, traditional contrastive rhetoric has perpetuated static binaries between English…

  6. Excess Barium as a Paleoproductivity Proxy: A Reevaluation

    NASA Astrophysics Data System (ADS)

    Eagle, M.; Paytan, A.

    2001-12-01

    Marine barite may serve as a proxy to reconstruct past export production (Dymond, 1992). In most studies sedimentary barite accumulation is not measured directly, instead a parameter termed excess barium (Baexs), also referred to as biogenic barium, is used to estimate the barite content. Baexs is defined as the total Ba concentration in the sediment minus the Ba associated with terrigenous material. Baexs is calculated by normalization to a constant Ba/Al ratio, typically the average shale ratio. This application assumes that (1) all the Ba besides the fraction associated with terrigenous Al is in the form of barite (the phase related to productivity) (2) the Ba/Alshale is constant in space and time (3) all of the Al is associated with terrigenous matter. If these assumptions are invalidated however, this approach lead to significant errors in calculating export production rates. To test the validity of the use of Baexs as a proxy for barite we compared the Baexs in a wide range of core top sediments from different oceanic settings to the barite content in the same cores. We found that Baexs frequently overestimated the Ba fraction associated with barite and in several cases significant Baexs was measured in the cores where no barite was observed. We have also used a sequential leaching protocol (Collier and Edmond 1984) to determine Ba association with organic matter, carbonates, Fe-Mn hydroxides and silicates. While terrigenous Ba remains an important fraction, in our samples 25-95% of non-barite Ba was derived from other fractions, with Fe-Mn oxides contributing the most Ba. In addition we found that the Ba/Al ratio in the silicate fraction of our samples varied considerably from site to site. The above results suggest that at least two of the underlying assumptions for employing Baexs to reconstruct paleoproductivity are not always valid and previously published data from (Murray and Leinen 1993) indicate that the third assumption may also not hold in every

  7. Value of 24-hour Delayed Film of Barium Enema for Evaluation of Colon Transit Function in Young Children with Constipation

    PubMed Central

    Yoo, Ha Yeong; Son, Jae Sung; Park, Hye Won; Kwak, Byung Ok; Kim, Hyeong Su; Bae, Sun Hwan

    2016-01-01

    Background/Aims A colon transit time test using radio-opaque markers (CTTRM) is considered the gold standard for evaluating colon transit function. A 24-hour delayed film of barium enema (BE) has been used as a supplementary method in structural evaluations. The aim of this study was to evaluate the utility of a 24-hour delayed BE film for assessing colon transit function in young children with constipation. Methods In total, 93 children with constipation who performed both single-contrast BE and CTTRM were enrolled in this study. Of these, the data from 70 children were analyzed (males 33, females 37; mean age [range], 5.63 ± 2.94 [2–14] years). The basic principle of the study is “velocity = distance/time”. Time values were identified in both studies, and the colon length and distance of barium movement were measured on the 24-hour delayed BE film. Thus, colon transit velocity values could be calculated using both methods. The correlation between colon transit velocity using a 24-hour delayed BE film versus CTTRM was analyzed statistically. Results Median value (interquartile range) of colon transit velocity using CTTRM was 1.57 (1.07–2.89) cm/hr, and that using BE of that was 1.58 (0.94–2.07) cm/hr. The Spearman correlation coefficient was 0.438 (P < 0.001) for the overall group. The correlation was strongest in children younger than 4 years (r = 0.537, P = 0.032). Conclusions Although the correlation between BE and CTTRM was not very strong, the 24-hour delayed BE film could provide broad information about colon transit function in young children, especially those under 4 years who usually cannot undergo CTTRM. PMID:26979249

  8. Supramolecular curcumin-barium prodrugs for formulating with ceramic particles.

    PubMed

    Kamalasanan, Kaladhar; Anupriya; Deepa, M K; Sharma, Chandra P

    2014-10-01

    A simple and stable curcumin-ceramic combined formulation was developed with an aim to improve curcumin stability and release profile in the presence of reactive ceramic particles for potential dental and orthopedic applications. For that, curcumin was complexed with barium (Ba(2+)) to prepare curcumin-barium (BaCur) complex. Upon removal of the unbound curcumin and Ba(2+) by dialysis, a water-soluble BaCur complex was obtained. The complex was showing [M+1](+) peak at 10,000-20,000 with multiple fractionation peaks of MALDI-TOF-MS studies, showed that the complex was a supramolecular multimer. The (1)H NMR and FTIR studies revealed that, divalent Ba(2+) interacted predominantly through di-phenolic groups of curcumin to form an end-to-end complex resulted in supramolecular multimer. The overall crystallinity of the BaCur was lower than curcumin as per XRD analysis. The complexation of Ba(2+) to curcumin did not degrade curcumin as per HPLC studies. The fluorescence spectrum was blue shifted upon Ba(2+) complexation with curcumin. Monodisperse nanoparticles with size less than 200dnm was formed, out of the supramolecular complex upon dialysis, as per DLS, and upon loading into pluronic micelles the size was remaining in similar order of magnitude as per DLS and AFM studies. Stability of the curcumin was improved greater than 50% after complexation with Ba(2+) as per UV/Vis spectroscopy. Loading of the supramloecular nanoparticles into pluronic micelles had further improved the stability of curcumin to approx. 70% in water. These BaCur supramolecule nanoparticles can be considered as a new class of prodrugs with improved solubility and stability. Subsequently, ceramic nanoparticles with varying chemical composition were prepared for changing the material surface reactivity in terms of the increase in, degradability, surface pH and protein adsorption. Further, these ceramic particles were combined with curcumin prodrug formulations and optimized the curcumin release

  9. Template-Engaged Solid-State Synthesis of Barium Magnesium Silicate Yolk@Shell Particles and Their High Photoluminescence Efficiency.

    PubMed

    Chen, Xuncai; Kim, Woo-Sik

    2016-05-17

    This study presents a new synthetic method for fabricating yolk@shell-structured barium magnesium silicate (BMS) particles through a template-engaged solid-state reaction. First, as the core template, (BaMg)CO3 spherical particles were prepared based on the coprecipitation of Ba(2+) and Mg(2+) . These core particles were then uniformly shelled with silica (SiO2 ) by using CTAB as the structure-directing template to form (BaMg)CO3 @SiO2 particles with a core@shell structure. The (BaMg)CO3 @SiO2 particles were then converted to yolk@shell barium magnesium silicate (BMS) particles by an interfacial solid-state reaction between the (BaMg)CO3 (core) and the SiO2 (shell) at 750 °C. During this interfacial solid-state reaction, Kirkendall diffusion contributed to the formation of yolk@shell BMS particles. Thus, the synthetic temperature for the (BaMg)SiO4 :Eu(3+) phosphor is significantly reduced from 1200 °C with the conventional method to 750 °C with the proposed method. In addition, the photoluminescence intensity of the yolk@shell (BaMg)SiO4 :Eu(3+) phosphor was found to be 9.8 times higher than that of the conventional (BaMg)SiO4 :Eu(3+) phosphor. The higher absorption of excitation light by the structure of the yolk@shell phosphor is induced by multiple light-reflection and -scattering events in the interstitial void between the yolk and the shell. When preparing the yolk@shell (BaMg)SiO4 :Eu(3+) phosphor, a hydrogen environment for the solid-state reaction results in higher photoluminescence efficiency than nitrogen and air environments. The proposed synthetic method can be easily extended to the synthesis of other yolk@shell multicomponent metal silicates. PMID:27059894

  10. Barium-deficient celsian, Ba1-xAl2-2xSi2+2xO8 (x = 0.20 or 0.06).

    PubMed

    Skellern, Matthew G; Howie, R Alan; Lachowski, Eric E; Skakle, Janet M S

    2003-02-01

    Barium-deficient forms of celsian (barium aluminium silicate) with the formula Ba(1-x)Al(2-2x)Si(2+2x)O(8) (x = 0.20 and 0.06) have been identified. In contrast with the celsian-orthoclase solid solutions which have been reported previously, these forms, refined in the space group C2/m, with Ba and one O atom in the 4i sites with m site symmetry, and a further O atom in a 4g site with twofold axial symmetry, suggest a slight solid solution with silica. The serendipitous preparation of the compounds represents a possible hazard associated with solid-state synthesis. PMID:12574637

  11. Active experiments in space in conjunction with Skylab. [barium plasma injection experiment and magnetic storm of March 7, 1972

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.

    1974-01-01

    Two papers are presented which relate to the Skylab barium shaped charge experiments. The first describes the L=6.6 OOSIK barium plasma injection experiment and magnetic storm of March 7, 1972. Rocket payload, instrumentation, data reduction methods, geophysical environment at the time of the experiment, and results are given. The second paper presents the observation of an auroral Birkeland current which developed from the distortion of a barium plasma jet during the above experiment.

  12. Compressive phase contrast tomography

    NASA Astrophysics Data System (ADS)

    Maia, F.; MacDowell, A.; Marchesini, S.; Padmore, H. A.; Parkinson, D. Y.; Pien, J.; Schirotzek, A.; Yang, C.

    2010-08-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  13. Compressive Phase Contrast Tomography

    SciTech Connect

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-09-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  14. Method of preparing barium, titanium, zirconium oxide ferroelectric ceramic composition

    SciTech Connect

    McSweeney, R.T.; Zuk, K.

    1991-07-16

    This patent describes a method for preparing a barium titanium zirconium oxide ferroelectric ceramic composition. It comprises reacting tetraalkyl titanate and tetraalkyl zirconate in appropriate amounts to produce (Ti{sub 1{minus}x}Zr{sub x}) alkoxide wherein 021 x {le} 0.25; reacting the (Ti{sub 1{minus}x}Sr{sub x}) alkoxide to form a two phase mixture of TiZrO{sub 4} and (Ti{sub 1{minus}s}Zr{sub s})O{sub 2}, wherein s is the solubility limit for ZrO{sub 2} in TiO{sub 2}; admixing the (Ti{sub 1{minus}s}Zr{sub s})O{sub 2} and TiZrO{sub 4} with a BaO precursor, the BaO precursor, (Ti{sub 1{minus}s}Zr{sub s})O{sub 2} and TiZrO{sub 4}; and heading the admixture for a period of time and at a sufficient temperature to produce Ba(Ti{sub 1{minus}x}Zr{sub x})O{sub 3} wherein 0 {lt} x {le} 0.25.

  15. Barium in landscape components of the western Transbaikal region

    NASA Astrophysics Data System (ADS)

    Kashin, V. K.

    2015-10-01

    Barium concentrations in parent materials, soils, and plants of the forest-steppe, steppe, and dry steppe landscapes of the Transbaikal region have been studied. The average concentration of this element in rocks and soils of this region exceeds its clarke by 1.8-2.1 times. A positive correlation between the contents of Ba in soils, soil-forming rocks, and plants has been found. The concentration of Ba in soils does not correlate with the soil pH and humus content. Distribution patterns of Ba in the soil profiles have been characterized. With respect to the coefficient of the biological uptake by plants, Ba is assigned to the group of low accumulation (0.55-0.65) for mineral soils and of strong accumulation (6.0) for alluvial bog soils. Average concentrations of Ba in the steppe, meadow, and cultivated vegetation of the region are 1.9-2.3 times higher in comparison with the average concentration of this element in plants of the continents. The biological migration of Ba is most active in meadow landscapes, whereas steppe landscapes are characterized by the least active biological migration of this element.

  16. Two new barium sulfonates with pillared layered structures

    NASA Astrophysics Data System (ADS)

    Yang, Jin; Li, Li; Ma, Jian-Fang; Liu, Ying-Ying; Ma, Ji-Cheng

    2006-08-01

    The reactions of BaCl 2·2H 2O with NaHL a and K 3L b (H 2L a=4-hydroxybenzenesulfonic acid, H 3L b=4-hydroxy-5-nitro-1,3-benzenedisulfonic acid) gave two pillared layered coordination polymers: Ba(HL a)(Cl) 1 and KBaL b(H 2O) 32, respectively. The crystal structures were determined by X-ray diffraction method and refined by full-matrix least-squares methods to R=0.0509 and wR=0.1216 using 1455 reflections with I>2 σ( I) for 1; and R=0.0288 and wR=0.0727 using 2661 reflections with I>2 σ( I) for 2. The interesting feature of compound 1 is the coordination actions of chloride anions, which help to form the polymeric layers by bridging barium cations. In compound 2 the Lb3- anion acts as an unusual dodecadente ligand to form a coordination polymer with pillared layered structure.

  17. Two new barium sulfonates with pillared layered structures

    NASA Astrophysics Data System (ADS)

    Yang, Jin; Li, Li; Ma, Jian-Fang; Liu, Ying-Ying; Ma, Ji-Cheng

    2006-05-01

    The reactions of BaCl 2·2H 2O with NaHL a and K 3L b (H 2L a=4-hydroxybenzenesulfonic acid, H 3L b=4-hydroxy-5-nitro-1,3-benzenedisulfonic acid) gave two pillared layered coordination polymers: Ba(HL a)(Cl) 1 and KBaL b(H 2O) 32, respectively. The crystal structures were determined by X-ray diffraction method and refined by full-matrix least-squares methods to R=0.0509 and wR=0.1216 using 1455 reflections with I>2 σ( I) for 1; and R=0.0288 and wR=0.0727 using 2661 reflections with I>2 σ( I) for 2. The interesting feature of compound 1 is the coordination actions of chloride anions, which help to form the polymeric layers by bridging barium cations. In compound 2 the Lb3- anion acts as an unusual dodecadente ligand to form a coordination polymer with pillared layered structure.

  18. Thermoelectric Properties of Barium Plumbate Doped by Alkaline Earth Oxides

    NASA Astrophysics Data System (ADS)

    Eufrasio, Andreza; Bhatta, Rudra; Pegg, Ian; Dutta, Biprodas

    Ceramic oxides are now being considered as a new class of thermoelectric materials because of their high stability at elevated temperatures. Such materials are especially suitable for use as prospective thermoelectric power generators because high temperatures are encountered in such operations. The present investigation uses barium plumbate (BaPbO3) as the starting material, the thermoelectric properties of which have been altered by judicious cation substitutions. BaPbO3 is known to exhibit metallic properties which may turn semiconducting as a result of compositional changes without precipitating a separate phase and/or altering the basic perovskite crystal structure. Perovskite structures are noted for their large interstitial spaces which can accommodate a large variety of ``impurity'' ions. As BaPbO3 has high electrical conductivity, σ = 2.43x105Ω-1 m-1 at room temperature, its thermopower, S, is relatively low, 23 μV/K, as expected. With a thermal conductivity, k, of 4.83Wm-1K-1, the figure of merit (ZT =S2 σ Tk-1) of BaPbO3 is only 0.01 at T = 300K. The objective of this investigation is to study the variation of thermoelectric properties of BaPbO3 as Ba and Pb ions are systematically substituted by alkaline earth ions.

  19. The chemical composition of the mild barium star HD 202109

    NASA Astrophysics Data System (ADS)

    Yushchenko, A. V.; Gopka, V. F.; Kim, C.; Liang, Y. C.; Musaev, F. A.; Galazutdinov, G. A.

    2004-01-01

    We present chemical abundances of the mild barium star HD 202109 (\\zeta Cyg) determined from the analysis of a spectrum obtained by using the 2-m telescope at the Peak Terskol Observatory and a high-resolution spectrometer with R=80 000, signal to noise ratio >100. We also present the atmospheric parameters of the star determined using various methods including iron-line abundance analysis. For line identifications, we use whole-range synthetic spectra computed from Kurucz's database and the latest lists of spectral lines. Among the determined abundances of 51 elements, those of P, S, K, Cu, Zn, Ge, Rb, Sr, Nb, Mo, Ru, Rh, Pd, In, Sm, Gd, Tb, Dy, Er, Tm, Hf, Os, Ir, Pt, Tl, and Pb were not investigated previously. Assuming that the overabundance pattern of Ba stars is due to binary accretion, the observed abundance pattern of the neutron-capture process elements in HD 202109 can be explained by combining the AGB star nucleosynthesis and the wind accretion scenario. Based on observations obtained at the 2-m telescope of Peak Terskol observatory near Mt. Elbrus, Northern Caucasus, Russia - International Center for Astronomical, Medical and Ecological Research (ICAMER), Ukraine & Russia.

  20. Impact of vanadium ions in barium borate glass.

    PubMed

    Abdelghany, A M; Hammad, Ahmed H

    2015-02-25

    Combined optical and infrared spectral measurements of prepared barium borate glasses containing different concentrations of V2O5 were carried out. Vanadium containing glasses exhibit extended UV-visible (UV/Vis.) bands when compared with base binary borate glass. UV/Vis. spectrum shows the presence of an unsymmetrical strong UV broad band centered at 214 nm attributed to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of such glass. The calculated direct and indirect optical band gaps are found to decrease with increasing the vanadium content (2.9:137 for indirect and 3.99:2.01 for direct transition). This change was discussed in terms of structural changes in the glass network. Infrared absorption spectra of the glasses reveal the appearance of both triangular and tetrahedral borate units. Electron spin resonance analyses indicate the presence of unpaired species in sufficient quantity to be identified and to confirm the spectral data. PMID:25194319

  1. Nanoscale inhomogeneities in yttrium-barium-copper-oxide (YBCO) superconductors

    NASA Astrophysics Data System (ADS)

    Islam, Zahirul; Sinha, S. K.; Lang, J. C.; Liu, X.; Haskel, D.; Moss, S. C.; Srajer, G.; Veal, B. W.; Wermeille, D.; Lee, D. R.; Haeffner, D. R.; Welp, U.; Wochner, P.

    2004-03-01

    X-ray diffraction studies at the Advanced Photon Source reveal that nanoscale inhomogeneities, electronic or structural in origin, form in yttrium-barium-copper-oxide (YBa_2Cu_3O_6+x) superconductors and coexist with the superconducting (SC) state. Diffuse scattering from these inhomogeneous superstructures is due to atomic displacements with respect to equilibrium lattice sites (Z. Islam et al. Phys. Rev. B 66, 92501 (2002)), that are characterized by a wavevector of the form q=(q_x,0,0), where qx varies with hole doping from 2 unit cells (along shorter Cu-O-Cu direction) for very low doping to 4 unit cells at optimal doping. Interestingly, while these superstructures are 3-dimensionally ordered when the SC state is weakened (e.g., at x=0.4), as the doping increases, they become quasi 1D with correlation lengths comparable to SC coherence lengths in these cuprates. Recent first-principles calculations (D. de Fontaine et al., to be published) for the x=0.63 compound show that atomic displacements consistent with experimental data can be the result of ordering of O vacancies in YBCO. Models for various superstructures and their role in the phase diagram will be discussed.

  2. Barium oxide, calcium oxide, magnesia, and alkali oxide free glass

    DOEpatents

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

    A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

  3. Abundance analysis of s-process enhanced barium stars

    NASA Astrophysics Data System (ADS)

    Mahanta, Upakul; Karinkuzhi, Drisya; Goswami, Aruna; Duorah, Kalpana

    2016-08-01

    Detailed chemical composition studies of stars with enhanced abundances of neutron-capture elements can provide observational constraints for neutron-capture nucleosynthesis studies and clues for understanding their contribution to the Galactic chemical enrichment. We present abundance results from high-resolution spectral analyses of a sample of four chemically peculiar stars characterized by s-process enhancement. High-Resolution spectra (R ˜42000) of these objects spanning a wavelength range from 4000 to 6800 Å, are taken from the ELODIE archive. We have estimated the stellar atmospheric parameters, the effective temperature Teff, the surface gravity log g, and metallicity [Fe/H] from local thermodynamic equilibrium analysis using model atmospheres. We report estimates of elemental abundances for several neutron-capture elements, Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu and Dy. While HD 49641 and HD 58368 show [Ba/Fe] ≥ 1.16 the other two objects HD 119650 and HD 191010 are found to be mild barium stars with [Ba/Fe] ˜ 0.4. The derived abundances of the elements are interpreted on the basis of existing theories for understanding their origin and evolution.

  4. Barium from a mini r-process in supernovae

    NASA Technical Reports Server (NTRS)

    Heymann, D.

    1983-01-01

    McCulloch and Wasserburg (1978) have reported nonlinear isotopic anomalies in barium for two Ca-Al-rich inclusions of the Allende carbonaceous chondrite, known as EK-1-4-1 and C-1. In an attempt to account for these anomalies, it has been proposed that Ba from an r-process of nucleosynthesis, containing Ba-135 and Ba-137, was injected into the primeval color system but was not totally homogenized. Questions arise in connection with the relations of Xe isotopes in carbonaceous chondrites. This has prompted Heymann and Dziczkaniec (1979, 1980, 1981) to study the formation of r-Xe, r-Kr, and r-Te by the mini r-process which is thought to occur in the O, Ne-rich shells of Type II supernovae. Lee et al. (1979) have studied the formation of r-Ba, r-Nd, and r-Sm by the same process. Certain differences regarding the approaches used by Lee et al. and by Heymann and Dziczkaniec make it necessary to restudy the work of Lee et al. Attention is given to the survival probabilities of nuclear species of interest, taking into accounts the elements Cs, Ba, I, and Xe.

  5. Properties of barium strontium titanate at millimeter wave frequencies

    SciTech Connect

    Osman, Nurul; Free, Charles

    2015-04-24

    The trend towards using higher millimetre-wave frequencies for communication systems has created a need for accurate characterization of materials to be used at these frequencies. Barium Strontium Titanate (BST) is a ferroelectric material whose permittivity is known to change as a function of applied electric field and have found varieties of application in electronic and communication field. In this work, new data on the properties of BST characterize using the free space technique at frequencies between 145 GHz and 155 GHz for both thick film and bulk samples are presented. The measurement data provided useful information on effective permittivity and loss tangent for all the BST samples. Data on the material transmission, reflection properties as well as loss will also be presented. The outcome of the work shows through practical measurement, that BST has a high permittivity with moderate losses and the results also shows that BST has suitable properties to be used as RAM for high frequency application.

  6. Dielectric and Impedance Spectroscopy of Barium Bismuth Vanadate Ferroelectrics

    NASA Astrophysics Data System (ADS)

    Sutar, B. C.; Choudhary, R. N. P.; Das, Piyush R.

    2014-07-01

    Structural, micro-structural and electrical properties of barium bismuth vanadate Ba(Bi0.5V0.5)O3 ceramics were investigated. X-ray diffraction (XRD) analysis of the prepared material confirmed the formation of the compound with monoclinic crystal system. Scanning electron microscopy (SEM) of the compound exhibits well-defined grains that are uniformly distributed throughout the surface of the sample. Dielectric properties of the compound were studied as a function of temperature at different frequencies. An observation of dielectric anomaly at 295 °C is due to ferroelectric phase transition that was later confirmed by the appearance of hysteresis loop. Detailed studies of complex impedance spectroscopy have provided a better understanding of the relaxation process and correlations between the microstructure-electrical properties of the materials. The nature of frequency dependence of ac conductivity obeys the Debye power law. The dc conductivity, calculated from the ac conductivity spectrum, shows the negative temperature coefficient of resistance behavior similar to that of a semiconductor.

  7. Hydrogen diffusion in lead zirconate titanate and barium titanate

    SciTech Connect

    Alvine, K. J.; Vijayakumar, M.; Bowden, M. E.; Schemer-Kohrn, A. L.; Pitman, S. G.

    2012-08-28

    Hydrogen is a potential clean-burning, next-generation fuel for vehicle and stationary power. Unfortunately, hydrogen is also well known to have serious materials compatibility issues in metals, polymers, and ceramics. Piezoelectric actuator materials proposed for low-cost, high efficiency high-pressure hydrogen internal combustion engines (HICE) are known to degrade rapidly in hydrogen. This limits their potential use and poses challenges for HICE. Hydrogen-induced degradation of piezoelectrics is also an issue for low-pressure hydrogen passivation in ferroelectric random access memory. Currently, there is a lack of data in the literature on hydrogen species diffusion in piezoelectrics in the temperature range appropriate for the HICE as charged via a gaseous route. We present 1HNMR quantification of the local hydrogen species diffusion within lead zirconate titanate and barium titanate on samples charged by exposure to high-pressure gaseous hydrogen ~32 MPa. We discuss results in the context of theoretically predicted interstitial hydrogen lattice sites and aqueous charging experiments from existing literature.

  8. Characterization of A-site deficient samarium doped barium titanate

    NASA Astrophysics Data System (ADS)

    Ganguly, M.; Rout, S. K.; Woo, W. S.; Ahn, C. W.; Kim, I. W.

    2013-02-01

    Ba1-xSm2x/3TiO3 (0.00≤x≤0.10, in a step of 0.02) ceramics have been prepared through solid state reaction route. Structural studies (XRD, FTIR, Raman) suggested a tetragonal symmetry of all the prepared ceramics and a decrease in tetragonality with increase in Sm content. Rietveld refinement technique has been employed to investigate the details of crystal structure and was found to be tetragonal at room temperature with space group P4mm. Photoluminescence study confirmed formation of shallow defects. The prepared materials are found to show photoemission in the violet, blue and green zone. Optical band gap values calculated from UV-visual diffuse reflectance spectra showed a decreasing trend in band gap values with increase in samarium concentration. Disk shaped pellets were prepared using PVA as binder. Scanning electron microscopy showed a drastic decrease in grain size on doping than undoped barium titanate. A regular increase in the grain size with increase in Sm content in the doped compositions is observed. Dielectric studies were performed over a wide temperature range from 15 K to 600 K at different frequencies. Normal ferroelectric character was obtained for all the compositions. A gradual decrease in the Curie temperature was noticed with increase in samarium content. P∼E hysteresis loops showed a domain pinning effect which increased successively resulting in a decrease in the values of remnant polarization and coercive fields.

  9. Review on dielectric properties of rare earth doped barium titanate

    NASA Astrophysics Data System (ADS)

    Ismail, Fatin Adila; Osman, Rozana Aina Maulat; Idris, Mohd Sobri

    2016-07-01

    Rare earth doped Barium Titanate (BaTiO3) were studied due to high permittivity, excellent electrical properties and have wide usage in various applications. This paper reviewed on the electrical properties of RE doped BaTiO3 (RE: Lanthanum (La), Erbium (Er), Samarium (Sm), Neodymium (Nd), Cerium (Ce)), processing method, phase transition occurred and solid solution range for complete study. Most of the RE doped BaTiO3 downshifted the Curie temperature (TC). Transition temperature also known as Curie temperature, TC where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-doped BaTiO3, Er-doped BaTiO3, Sm-doped BaTiO3, Nd-doped BaTiO3 and Ce-doped BaTiO3 had been proved to increase and the transition temperature or also known as TC also lowered down to room temperature as for all the RE doped BaTiO3 except for Er-doped BaTiO3.

  10. Electrical properties of lanthanum doped barium titanate ceramics

    SciTech Connect

    Vijatovic Petrovic, M.M.; Bobic, J.D.; Ramoska, T.; Banys, J.; Stojanovic, B.D.

    2011-10-15

    Pure and lanthanum doped barium titanate (BT) ceramics were prepared by sintering pellets at 1300 deg. C for 8 h, obtained from nanopowders synthesized by the polymeric precursor method. XRD results showed formation of a tetragonal structure. The presence of dopants changed the tetragonal structure to pseudo-cubic. The polygonal grain size was reduced up to 300 nm with addition of lanthanum as a donor dopant. Determined dielectric properties revealed that lanthanum modified BT ceramics possessed a diffused ferroelectric character in comparison with pure BT that is a classical ferroelectric material. In doped BT phase transition temperatures were shifted to lower temperatures and dielectric constant values were much higher than in pure BT. A modified Currie Weiss law was used to explore the connection between the doping level and degree of diffuseness of phase transitions. Impedance spectroscopy measurements were carried out at different temperatures in order to investigate electrical resistivity of materials and appearance of a PTCR effect. - Highlights: {yields} Pure and lanthanum doped BaTiO{sub 3} were prepared by polymeric precursors method. {yields} Change of structure from tetragonal to pseudo-cubic. {yields} Lanthanum as a donor dopant influenced on change of ferro-para phase transition. {yields} The diffuseness factor indicated the formation of diffuse ferroelectric material. {yields} Lanthanum affected on PTCR effect appearance in BT ceramics.

  11. Contrast of local air-sea relationships between 10-20-day and 30-60-day intraseasonal oscillations during May-September over the South China Sea and western North Pacific

    NASA Astrophysics Data System (ADS)

    Ye, Kunhui; Wu, Renguang

    2015-12-01

    Present study compares local air-sea relationship of 10-20-day and 30-60-day intraseasonal oscillations (ISOs) over the South China Sea (SCS) and western North Pacific (WNP) during May through September for the period 1998-2010. It is shown that sea surface temperature (SST) has a larger intraseasonal variance in the North Indian Ocean, the SCS, and subtropical WNP on the 30-60-day time scale, but in tropical WNP on the 10-20-day time scale. The local correlation of SST with rain, surface shortwave radiation (SWR) and latent heat flux (LHF) displays a southwest-northeast tilted structure on the 10-20-day time scale, but a broad west-east pattern with a larger correlation on the 30-60-day time scale. The time of SST leading rain is larger in off-equatorial regions than in near-equatorial regions for both types of ISOs, whereas the time of rain leading SST is larger in near-equatorial regions than in off-equatorial regions. A similar feature is seen for SWR, but an opposite feature for LHF. The atmospheric ISOs induce intraseasonal SST variations through cloud-radiation and wind-evaporation changes. The intraseasonal SST variations feedback on the atmosphere through modulation of atmospheric stability over off-equatorial regions on both timescales. The SST impacts on the atmosphere appear larger on the 30-60-day time scale than on the 10-20-day time scale. The distinct spatial patterns of local air-sea relationship on the two types of ISOs are associated with different spatial structures in both atmospheric ISO-associated SWR and LHF anomalies and SST-induced atmospheric stability anomalies.

  12. Microwave absorption properties of Al- and Cr-substituted M-type barium hexaferrite

    NASA Astrophysics Data System (ADS)

    Qiu, Jianxun; Gu, Mingyuan; Shen, Haigen

    2005-09-01

    Aluminum- and chromium-substituted barium ferrite particles with single magnetic domain were prepared using self-propagating combustion method. The crystalline structure, size, coercivity and microwave absorption property of the particles were investigated by means of X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry and vector network analyzer. The results show that the crystalline structure of BaFe 12-xAl xO 19 is still hexagonal. But when the chromium substitution amount y exceeds 0.6, the extra chromium ions cannot enter the lattice of BaFe 12-yCr yO 19. After Fe 3+ is partly substituted with Al 3+ and Cr 3+, the microwave absorption properties of barium ferrite are improved. The maximum absorption reaches 34.76 dB. The ferromagnetic resonance is an important channel of barium ferrite to absorb microwaves with high frequency. Aluminum and chromium substitutions change the ferromagnetic resonant frequency of barium ferrite. The multipeak phenomenon of the ferromagnetic resonance increases the microwave absorption capability of barium ferrite.

  13. High pressure-low temperature phase diagram of barium: Simplicity versus complexity

    NASA Astrophysics Data System (ADS)

    Desgreniers, Serge; Tse, John S.; Matsuoka, Takahiro; Ohishi, Yasuo; Li, Quan; Ma, Yanming

    2015-11-01

    Barium holds a distinctive position among all elements studied upon densification. Indeed, it was the first example shown to violate the long-standing notion that high compression of simple metals should preserve or yield close-packed structures. From modest pressure conditions at room temperature, barium transforms at higher pressures from its simple structures to the extraordinarily complex atomic arrangements of the incommensurate and self-hosting Ba-IV phases. By a detailed mapping of the pressure/temperature structures of barium, we demonstrate the existence of another crystalline arrangement of barium, Ba-VI, at low temperature and high pressure. The simple structure of Ba-VI is unlike that of complex Ba-IV, the phase encountered in a similar pressure range at room temperature. First-principles calculations predict Ba-VI to be stable at high pressure and superconductive. The results illustrate the complexity of the low temperature-high pressure phase diagram of barium and the significant effect of temperature on structural phase transformations.

  14. High pressure–low temperature phase diagram of barium: Simplicity versus complexity

    SciTech Connect

    Desgreniers, Serge; Tse, John S.; Matsuoka, Takahiro; Ohishi, Yasuo

    2015-11-30

    Barium holds a distinctive position among all elements studied upon densification. Indeed, it was the first example shown to violate the long-standing notion that high compression of simple metals should preserve or yield close-packed structures. From modest pressure conditions at room temperature, barium transforms at higher pressures from its simple structures to the extraordinarily complex atomic arrangements of the incommensurate and self-hosting Ba-IV phases. By a detailed mapping of the pressure/temperature structures of barium, we demonstrate the existence of another crystalline arrangement of barium, Ba-VI, at low temperature and high pressure. The simple structure of Ba-VI is unlike that of complex Ba-IV, the phase encountered in a similar pressure range at room temperature. First-principles calculations predict Ba-VI to be stable at high pressure and superconductive. The results illustrate the complexity of the low temperature-high pressure phase diagram of barium and the significant effect of temperature on structural phase transformations.

  15. Chromospherically active stars. 6: Giants with compact hot companions and the barium star scenario

    NASA Technical Reports Server (NTRS)

    Fekel, Francis C.; Henry, Gregory W.; Busby, Michael R.; Eitter, Joseph J.

    1993-01-01

    We have determined spectroscopic orbits for three chromospherically active giants that have hot compact companions. They are HD 160538 (K0 III + wd, P = 904 days), HD 165141 (G8 III + wd, P approximately 5200 days), and HD 185510 (K0 III + sdB, P = 20.6619 days). By fitting an IUE spectrum with theoretical models, we find the white dwarf companion of HD 165141 has a temperature of about 35000 K. Spectral types and rotational velocities have been determined for the three giants and distances have been estimated. These three systems and 39 Ceti are compared with the barium star mass-transfer scenario. The long-period mild barium giant HD 165141 as well as HD 185510 and 39 Ceti, which have relatively short periods and normal abundance giants, appear to be consistent with this scenario. The last binary, HD 160538, a system with apparently near solar abundances, a white dwarf companion, and orbital characteristics similar to many barium stars, demonstrates that the existence of a white-dwarf companion is insufficient to produce a barium star. The paucity of systems with confirmed white-dwarf companions makes abundance analyses of HD 160538 and HD 165141 of great value in examining the role of metallicity in barium star formation.

  16. Chromospherically active stars. 11: Giant with compact hot companions and the barium star scenario

    NASA Technical Reports Server (NTRS)

    Fekel, Francis C.; Henry, Gregory W.; Busby, Michael R.; Eitter, Joseph J.

    1993-01-01

    We have determined spectroscopic orbits for three chromsopherically active giants that have hot compact companions. They are HD 160538 (KO III + wd, P = 904 days), HD 165141 (G8 III + wd, P approximately 5200 days), and HD 185510 (KO III + sdB, P = 20.6619 days). By fitting an IUE spectrum with theoretical models, we find the white dwarf companion of HD 165141 has a temperature of about 35,000 K. Spectral types and rotational velocities have been determined for the three giants and distances have been estimated. These three systems and 39 Ceti are compared with the barium star mass-transfer scenario. The long-period mild barium giant HD 165141 as well as HD 185510 and 39 Ceti, which have relatively short periods and normal abundance giants, appear to be consistent with this scenario. The last binary, HD 160538, a system with apparently near solar abundances, a white dwarf companion, and orbital characteristics similar to many barium stars, demonstrates that the existence of a white dwarf companion is insufficient to produce a barium star. The paucity of systems with confirmed white dwarf companions makes abundance analyses of HD 160538 and HD 165141 of great value in examining the role of metallicity in barium star formation.

  17. Psychophysical contrast calibration

    PubMed Central

    To, Long; Woods, Russell L; Goldstein, Robert B; Peli, Eli

    2013-01-01

    Electronic displays and computer systems offer numerous advantages for clinical vision testing. Laboratory and clinical measurements of various functions and in particular of (letter) contrast sensitivity require accurately calibrated display contrast. In the laboratory this is achieved using expensive light meters. We developed and evaluated a novel method that uses only psychophysical responses of a person with normal vision to calibrate the luminance contrast of displays for experimental and clinical applications. Our method combines psychophysical techniques (1) for detection (and thus elimination or reduction) of display saturating nonlinearities; (2) for luminance (gamma function) estimation and linearization without use of a photometer; and (3) to measure without a photometer the luminance ratios of the display’s three color channels that are used in a bit-stealing procedure to expand the luminance resolution of the display. Using a photometer we verified that the calibration achieved with this procedure is accurate for both LCD and CRT displays enabling testing of letter contrast sensitivity to 0.5%. Our visual calibration procedure enables clinical, internet and home implementation and calibration verification of electronic contrast testing. PMID:23643843

  18. TWO BARIUM STARS IN THE OPEN CLUSTER NGC 5822

    SciTech Connect

    Katime Santrich, O. J.; Pereira, C. B.; De Castro, D. B. E-mail: claudio@on.br

    2013-08-01

    Open clusters are very useful examples to explain the constraint of the nucleosynthesis process with the luminosities of stars because the distances of the clusters are better known than those of field stars. We carried out a detailed spectroscopic analysis to derive the chemical composition of two red giants in the young open cluster NGC 5822, NGC 5822-2, and NGC 5822-201. We obtained abundances of C, N, O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd. The atmospheric parameters of the studied stars and their chemical abundances were determined using high-resolution optical spectroscopy. We employed the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. The abundances of the light elements were derived using the spectral synthesis technique. We found that NGC 5822-2 and -201 have, respectively, a mean overabundance of the elements created by the s-process, ''s'', with the notation [s/Fe] of 0.77 {+-} 0.12 and 0.83 {+-} 0.05. These values are higher than those for field giants of similar metallicity. We also found that NGC 5822-2 and -201 have, respectively, luminosities of 140 L{sub Sun} and 76 L{sub Sun }, which are much lower than the luminosity of an asymptotic giant branch star. We conclude that NGC 5822-2 and NGC 5822-201 are two new barium stars first identified in the open cluster NGC 5822. The mass transfer hypothesis is the best scenario to explain the observed overabundances.

  19. Dominant toughening mechanisms in barium aluminosilicate (BAS) glass-ceramics

    NASA Astrophysics Data System (ADS)

    Griggs, Jason Alan

    The purpose of this study was to develop a barium aluminosilicate (BAS) glass-ceramic with improved strength and fracture toughness by controlling the morphology of the constituent phases through a series of thermal crystallization treatments. The specific objectives of this study were to (1) determine which toughening mechanisms are active in the BAS system, (2) provide quantitative estimates of the relative contributions of those mechanisms, and (3) identify the processing conditions that correspond to a glass-ceramic with optimal fracture toughness. The BAS system was chosen for this study because of its potential applications in CAD-CAM production of dental prostheses. It is concluded that load sharing and crack deflection are the only major sources of toughening in the BAS system. Theoretical predictions for toughening increases due to load sharing and crack deflection are insufficient to account for 100% of the increases observed. The excess increase in fracture toughness is produced by thermal mismatch between and crystal and glass phases. The strength and fracture toughness of BAS glass-ceramics are shown to increase with increasing crystal growth time over the entire range of treatments studied. The strength and fracture toughness increased from 63 ± 8 MPa and 0.89 ± 0.05 MPa*msp{1/2}, respectively for BAS glass to 141 ± 8 MPa and 1.87 ± 0.07 MPa*msp{1/2} respectively for a glass-ceramic treated for 256 h at 975sp°C. Fracture toughness was also shown to increase with increasing mean crystal size. A non-stoichiometric glass composition results in thermal compatibility between the glass and crystal phases, eliminating the weakening at large crystal sizes that can be associated with a spontaneous microcracking mechanism.

  20. Evaluation of antibacterial properties of Barium Zirconate Titanate (BZT) nanoparticle

    PubMed Central

    Mohseni, Simin; Aghayan, Mahdi; Ghorani-Azam, Adel; Behdani, Mohammad; Asoodeh, Ahmad

    2014-01-01

    So far, the antibacterial activity of some organic and inorganic compounds has been studied. Barium zirconate titanate [Ba(ZrxTi1-x)O3] (x = 0.05) nanoparticle is an example of inorganic materials. In vitro studies have provided evidence for the antibacterial activity of this nanoparticle. In the current study, the nano-powder was synthesized by sol-gel method. X-ray diffraction showed that the powder was single-phase and had a perovskite structure at the calcination temperature of 1000 °C. Antibacterial activity of the desired nanoparticle was assessed on two gram-positive (Staphylococcus aureus PTCC1431 and Micrococcus luteus PTCC1625) and two gram-negative (Escherichia coli HP101BA 7601c and clinically isolated Klebsiella pneumoniae) bacteria according to Radial Diffusion Assay (RDA). The results showed that the antibacterial activity of BZT nano-powder on both gram-positive and gram-negative bacteria was acceptable. The minimum inhibitory concentration of this nano-powder was determined. The results showed that MIC values for E. coli, K. pneumoniae, M. luteus and S. aureus were about 2.3 μg/mL, 7.3 μg/mL, 3 μg/mL and 12 μg/mL, respectively. Minimum bactericidal concentration (MBC) was also evaluated and showed that the growth of E. coli, K. pneumoniae, M. luteus and S. aureus could be decreased at 2.3, 14, 3 and 18 μg/mL of BZT. Average log reduction in viable bacteria count in time-kill assay ranged between 6 Log10 cfu/mL to zero after 24 h of incubation with BZT nanoparticle. PMID:25763046

  1. Kinetic analysis of barium currents in chick cochlear hair cells.

    PubMed Central

    Zidanic, M; Fuchs, P A

    1995-01-01

    Inward barium current (IBa) through voltage-gated calcium channels was recorded from chick cochlear hair cells using the whole-cell clamp technique. IBa was sensitive to dihydropyridines and insensitive to the peptide toxins omega-agatoxin IVa, omega-conotoxin GVIa, and omega-conotoxin MVIIC. Changing the holding potential over a -40 to -80 mV range had no effect on the time course or magnitude of IBa nor did it reveal any inactivating inward currents. The activation of IBa was modeled with Hodgkin-Huxley m2 kinetics. The time constant of activation, tau m, was 550 microseconds at -30 mV and gradually decreased to 100 microseconds at +50 mV. A Boltzmann fit to the activation curve, m infinity, yielded a half activation voltage of -15 mV and a steepness factor of 7.8 mV. Opening and closing rate constants, alpha m and beta m, were calculated from tau m and m infinity, then fit with modified exponential functions. The H-H model derived by evaluating the exponential functions for alpha m and beta m not only provided an excellent fit to the time course of IBa activation, but was predictive of the time course and magnitude of the IBa tail current. No differences in kinetics or voltage dependence of activation of IBa were found between tall and short hair cells. We conclude that both tall and short hair cells of the chick cochlea predominantly, if not exclusively, express noninactivating L-type calcium channels. These channels are therefore responsible for processes requiring voltage-dependent calcium entry through the basolateral cell membrane, such as transmitter release and activation of Ca(2+)-dependent K+ channels. PMID:7787021

  2. Electrical properties of niobium doped barium bismuth-titanate ceramics

    SciTech Connect

    Bobić, J.D.; Vijatović Petrović, M.M.; Banys, J.; Stojanović, B.D.

    2012-08-15

    Highlights: ► Pure and doped BaBi{sub 4}Ti{sub 4}O{sub 15} were prepared via the solid-state reaction method. ► The grain size was suppressed in Nb-doped samples. ► The diffuseness of the dielectric peak increased with dopant concentration. ► Niobium affected on relaxor behavior of barium bismuth titanate ceramics. ► The conductivity change was noticed in doped samples. -- Abstract: BaBi{sub 4}Ti{sub 4–5/4x}Nb{sub x}O{sub 15} (BBNTx, x = 0, 0.05, 0.15, 0.30) ceramics have been prepared by solid state method. XRD data indicate the formation of single-phase-layered perovskites for all compositions. SEM micrographs suggest that the grain size decreases with Nb doping. The effect of niobium doping on the dielectric and relaxor behavior of BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics was investigated in a wide range of temperatures (20–777 °C) and frequencies (1.21 kHz to 1 MHz). Nb doping influences T{sub c} decrease as well as the decrease of dielectric permittivity at Curie temperature. At room temperature, undoped BaBi{sub 4}Ti{sub 4}O{sub 15} exhibits dielectric constant of ∼204 at 100 kHz, that slightly increases with Nb doping. The conductivity of BBNT5 ceramics is found to be lower than that of other investigated compositions. The value of activation energy of σ{sub DC} was found to be 0.89 eV, 1.01 eV, 0.93 eV and 0.71 eV for BBT, BBNT5, BBNT15 and BBNT30, respectively.

  3. FIRST DIRECT EVIDENCE THAT BARIUM DWARFS HAVE WHITE DWARF COMPANIONS

    SciTech Connect

    Gray, R. O.; McGahee, C. E.; Griffin, R. E. M.; Corbally, C. J. E-mail: cmcgahe@g.clemson.edu E-mail: corbally@as.arizona.edu

    2011-05-15

    Barium II (Ba) stars are chemically peculiar F-, G-, and K-type objects that show enhanced abundances of s-process elements. Since s-process nucleosynthesis is unlikely to take place in stars prior to the advanced asymptotic giant branch (AGB) stage, the prevailing hypothesis is that each present Ba star was contaminated by an AGB companion which is now a white dwarf (WD). Unless the initial mass ratio of such a binary was fairly close to unity, the receiving star is thus at least as likely to be a dwarf as a giant. So although most known Ba stars appear to be giants, the hypothesis requires that Ba dwarfs be comparably plentiful and moreover that they should all have WD companions. However, despite dedicated searches with the IUE satellite, no WD companions have been directly detected to date among the classical Ba dwarfs, even though some 90% of those stars are spectroscopic binaries, so the contamination hypothesis is therefore presently in some jeopardy. In this paper, we analyze recent deep, near-UV and far-UV Galaxy Evolution Explorer (GALEX) exposures of four of the brightest of the class (HD 2454, 15360, 26367, and 221531), together with archived GALEX data for two newly recognized Ba dwarfs: HD 34654 and HD 114520 (which also prove to be spectroscopic binaries). The GALEX observations of the Ba dwarfs as a group show a significant far-UV excess compared to a control sample of normal F-type dwarfs. We suggest that this ensemble far-UV excess constitutes the first direct evidence that Ba dwarfs have WD companions.

  4. Gadofullerene MRI contrast agents.

    PubMed

    Bolskar, Robert D

    2008-04-01

    A promising new class of MRI contrast-enhancing agents with high relaxivities is based on gadolinium-containing metallofullerenes, which are also termed gadofullerenes. Detailed study of the water-proton relaxivity properties and intermolecular nanoclustering behavior of gadofullerene derivatives has revealed valuable information about their relaxivity mechanisms and given a deeper understanding of this new class of paramagnetic contrast agent. Here, the latest findings on water-solubilized gadofullerene materials and how these findings relate to their future applications in MRI are reviewed and discussed. PMID:18373426

  5. Reverse microemulsion-mediated synthesis and structural evolution of barium hexaaluminate nanoparticles

    SciTech Connect

    Zarur, A.J.; Hwu, H.H.; Ying, J.Y.

    2000-04-04

    Nanocrystalline barium hexaaluminate has been successfully synthesized through the use of a reverse microemulsion as a medium for controlled hydrolysis and polycondensation of barium and aluminum alkoxides. The nanoparticles derived were characterized with electron microscopy, X-ray diffraction, and nitrogen adsorption analysis. This novel material possessed a well-defined particle morphology and an ultrahigh surface area, and exhibited excellent catalytic performance in methane combustion. Its structural evolution was found to be strongly dependent on synthesis parameters, such as water/alkoxide ratio and aging period. Powder recovery and drying techniques also had an important impact on particle agglomeration and structural development. Through the unique synthesis approach described, barium hexaaluminate with superb thermal stability was achieved, with surface areas in excess of 100 m{sup 2}/g retained even after calcination at 1,300 C.

  6. The review of various synthesis methods of barium titanate with the enhanced dielectric properties

    NASA Astrophysics Data System (ADS)

    More, S. P.; Topare, R. J.

    2016-05-01

    The Barium Titanate is a very well known dielectric ceramic belongs to perovskite structure. It has very wide applications in the field of electronic, electro ceramic, electromechanical and electro-optical applications. Barium Titanate has very high dielectric constant as well as low dielectric loss. Substituted dielectrics are one of the most important technological compounds in modern electro ceramics. Its electrical properties can be tuned flexibly by a simple substitution technique. This has encouraged researchers to select a typical cation to be substituted at cationic sites. In the present paper, the review of various synthesis methods of Barium Titanate compound with the effect of different dopants, the grain size on the dielectric properties at various temperatures is discussed.

  7. Improved chemical stability and conductivity of barium cerate nanopowders by Lanthanum doping.

    PubMed

    Lee, Hunhyeong; Park, Inyu; Shin, Dongwook

    2013-09-01

    Despite of the highest proton conductivity, barium cerate electrolytes are well known for the deficiency of chemical stability at elevated temperature under CO2 atmosphere. This work is focused on improving chemical stability of lanthanum doped barium cerate (BCL) powder for electrolyte. Although lanthanum doping causes distortion of perovskite structure lattice, immoderate doping could stabilize structure due to increasing symmetry of structure lattices. The thermogravimetric analysis and AC impedance measurements revealed that the lanthanum doping suppresses the reaction between barium and carbonate and this effect results in sufficient improvement in ionic conductivity in operating temperatures range. It was confirmed that BaCe0.7La0.3O3-delta (BCL30) was the most stable composition and the conductivity of BCL30 is high as 3.8 S x cm(-1) x K at 700 degrees C. PMID:24205607

  8. Barium isotopes in individual presolar silicon carbide grains from the Murchison meteorite.

    SciTech Connect

    Savina, M. R.; Davis, A. M.; Tripa, C. E.; Pellin, M. J.; Clayton, R. N.; Lewis, R. S.; Amari, S.; Gallino, R.; Lugaro, M.; Univ. of Chicago; Washington Univ.; Univ. di Torino; Cambridge Univ.

    2003-09-01

    Barium isotopic compositions of single 2.3-5.3 {mu}m presolar SiC grains from the Murchison meteorite were measured by resonant ionization mass spectrometry. Mainstream SiC grains are enriched in s-process barium and show a spread in isotopic composition from solar to dominantly s-process. In the relatively coarse grain size fraction analyzed, there are large grain-to-grain variations of barium isotopic composition. Comparison of single grain data with models of nucleosynthesis in asymptotic giant branch (AGB) stars indicates that the grains most likely come from low mass carbon-rich AGB stars (1.5 to 3 solar masses) of about solar metallicity and with approximately solar initial proportions of r- and s-process isotopes. Measurements of single grains imply a wide variety of neutron-to-seed ratios, in agreement with previous measurements of strontium, zirconium and molybdenum isotopic compositions of single presolar SiC grains.

  9. Solid solution barium-strontium chlorides with tunable ammonia desorption properties and superior storage capacity

    NASA Astrophysics Data System (ADS)

    Bialy, Agata; Jensen, Peter B.; Blanchard, Didier; Vegge, Tejs; Quaade, Ulrich J.

    2015-01-01

    Metal halide ammines are very attractive materials for ammonia absorption and storage-applications where the practically accessible or usable gravimetric and volumetric storage densities are of critical importance. Here we present, that by combining advanced computational materials prediction with spray drying and in situ thermogravimetric and structural characterization, we synthesize a range of new, stable barium-strontium chloride solid solutions with superior ammonia storage densities. By tuning the barium/strontium ratio, different crystallographic phases and compositions can be obtained with different ammonia ab- and desorption properties. In particular it is shown, that in the molar range of 35-50% barium and 65-50% strontium, stable materials can be produced with a practically usable ammonia density (both volumetric and gravimetric) that is higher than any of the pure metal halides, and with a practically accessible volumetric ammonia densities in excess of 99% of liquid ammonia.

  10. Phase transition studies in barium and strontium titanates at microwave frequencies

    NASA Technical Reports Server (NTRS)

    Dahiya, Jai N.

    1993-01-01

    The objectives were the following: to understand the phase transformations in barium and strontium titanates as the crystals go from one temperature to the other; and to study the dielectric behavior of barium and strontium titanate crystals at a microwave frequency of 9.12 GHz and as a function of temperature. Phase transition studies in barium and strontium titanate are conducted using a cylindrical microwave resonant cavity as a probe. The cavity technique is quite successful in establishing the phase changes in these crystals. It appears that dipole relaxation plays an important role in the behavior of the dielectric response of the medium loading the cavity as phase change takes place within the sample. The method of a loaded resonant microwave cavity as applied in this work has proven to be sensitive enough to monitor small phase changes of the cavity medium.

  11. Plasma irregularities caused by cycloid bunching of the CRRES G-2 barium release

    NASA Technical Reports Server (NTRS)

    Bernhardt, P. A.; Huba, J. D.; Pongratz, M. B.; Simons, D. J.; Wolcott, J. H.

    1993-01-01

    The Combined Release and Radiation Effects Satellite (CRRES) spacecraft carried a number of barium thermite canisters for release into the upper atmosphere. The barium release labeled G-2 showed evidence of curved irregularities not aligned with the ambient magnetic field B. The newly discovered curved structures can be explained by a process called cycloid bunching. Cycloid bunching occurs when plasma is created by photoionization of a neutral cloud injected at high velocity perpendicular to B. If the injection velocity is much larger than the expansion speed of the cloud, the ion trail will form a cycloid that has irregularities spaced by the product of the perpendicular injection speed and the ion gyroperiod, Images of the solar-illuminated barium ions are compared with the results of a three-dimensional kinetic simulation. Cycloid bunching is shown to be responsible for the rapid generation of both curved and field-aligned irregularities in the CRRES G-2 experiment.

  12. Prompt ionization in the CRIT II barium releases. [Critical Ionization Tests

    NASA Technical Reports Server (NTRS)

    Torbert, R. B.; Kletzing, C. A.; Liou, K.; Rau, D.

    1992-01-01

    Observations of electron and ion distributions inside a fast neutral barium jet in the ionosphere show significant fluxes within 4 km of release, presumably related to beam plasma instability processes involved in the Critical Ionization Velocity (CIV) effect. Electron fluxes exceeding 5 x 10 exp 12/sq cm-str-sec-keV were responsible for ionizing both the streaming barium and ambient oxygen. Resulting ion fluxes seem to be consistent with 1-2 percent ionization of the fast barium, as reported by optical observations, although the extended spatial distribution of the optically observed ions is difficult to reconcile with the in situ observations. When the perpendicular velocity of the neutrals falls below critical values, these processes shut off. Although these observations resemble the earlier Porcupine experimental results (Haerendel, 1982), theoretical understanding of the differences between these data and that of earlier negative experiments is still lacking.

  13. Observation and theory of the barium releases from the CRRES satellite

    NASA Technical Reports Server (NTRS)

    Bernhardt, P. A.; Huba, J. D.; Scales, W. A.; Wescott, E. M.; Stenbaek-Nielsen, H. C.

    1992-01-01

    The relationship between releases of barium from the NASA Combined Release and Radiation Effects Satellite (CRRES) and enhanced auroral activity is discussed with reference to observational data. Barium releases were conducted at a variety of altitudes and injection velocities, and plasma irregularities are reported as a result of the interactions. Auroral activity increased within 5 min of each release, and references are made to the effects on diamagnetic cavities, bulk ion motion, and stimulated electron and ion precipitation. Artificially created structured diamagnetic cavities are noted for each release, plasma waves are generated by the high-speed ion clouds, and enhanced ionization is found in the critical ionization-velocity process. Barium releases are effective in stimulating electron precipitation, and the observed irregularities are related to cycloid bunching of the initial ion distributions.

  14. Highly aligned arrays of high aspect ratio barium titanate nanowires via hydrothermal synthesis

    SciTech Connect

    Bowland, Christopher C.; Zhou, Zhi; Malakooti, Mohammad H.; Sodano, Henry A.

    2015-06-01

    We report on the development of a hydrothermal synthesis procedure that results in the growth of highly aligned arrays of high aspect ratio barium titanate nanowires. Using a multiple step, scalable hydrothermal reaction, a textured titanium dioxide film is deposited on titanium foil upon which highly aligned nanowires are grown via homoepitaxy and converted to barium titanate. Scanning electron microscope images clearly illustrate the effect the textured film has on the degree of orientation of the nanowires. The alignment of nanowires is quantified by calculating the Herman's Orientation Factor, which reveals a 58% improvement in orientation as compared to growth in the absence of the textured film. The ferroelectric properties of barium titanate combined with the development of this scalable growth procedure provide a powerful route towards increasing the efficiency and performance of nanowire-based devices in future real-world applications such as sensing and power harvesting.

  15. Characterization, sintering and dielectric properties of nanocrystalline barium titanate synthesized through a modified combustion process

    SciTech Connect

    George, C.N.; Thomas, J.K. Kumar, H.P.; Suresh, M.K.; Kumar, V.R.; Wariar, P.R.S.; Jose, R.; Koshy, J.

    2009-04-15

    Nanocrystalline barium titanate has been synthesized through a modified combustion process in a single step for the first time. The as-prepared barium titanate powder is cubic perovskite with lattice constant a = 4.018 A. The phase purity of the nanopowder was examined using thermo gravimetric analysis, differential thermal analysis and Fourier transform infrared spectroscopy. Transmission electron microscopic investigations have shown that the particle size of the as-prepared powder is in the range 20-40 nm. The agglomerate size distribution of the as-prepared powder was studied using atomic force microscopy. The nanoparticles of barium titanate were sintered to 97% of the theoretical density at a temperature of 1350 deg. C for 3 h. The microstructure of the sintered surface was examined using scanning electron microscopy. The dielectric constant and loss factor of the sintered pellets at 1 MHz measured at room temperature were 1223 and 3.5 x 10{sup -3} respectively.

  16. Spectroscopy of Ba and Ba+ deposits in solid xenon for barium tagging in nEXO

    NASA Astrophysics Data System (ADS)

    Mong, B.; Cook, S.; Walton, T.; Chambers, C.; Craycraft, A.; Benitez-Medina, C.; Hall, K.; Fairbank, W.; Albert, J. B.; Auty, D. J.; Barbeau, P. S.; Basque, V.; Beck, D.; Breidenbach, M.; Brunner, T.; Cao, G. F.; Cleveland, B.; Coon, M.; Daniels, T.; Daugherty, S. J.; DeVoe, R.; Didberidze, T.; Dilling, J.; Dolinski, M. J.; Dunford, M.; Fabris, L.; Farine, J.; Feldmeier, W.; Fierlinger, P.; Fudenberg, D.; Giroux, G.; Gornea, R.; Graham, K.; Gratta, G.; Heffner, M.; Hughes, M.; Jiang, X. S.; Johnson, T. N.; Johnston, S.; Karelin, A.; Kaufman, L. J.; Killick, R.; Koffas, T.; Kravitz, S.; Krücken, R.; Kuchenkov, A.; Kumar, K. S.; Leonard, D. S.; Licciardi, C.; Lin, Y. H.; Ling, J.; MacLellan, R.; Marino, M. G.; Moore, D.; Odian, A.; Ostrovskiy, I.; Piepke, A.; Pocar, A.; Retiere, F.; Rowson, P. C.; Rozo, M. P.; Schubert, A.; Sinclair, D.; Smith, E.; Stekhanov, V.; Tarka, M.; Tolba, T.; Twelker, K.; Vuilleumier, J.-L.; Walton, J.; Weber, M.; Wen, L. J.; Wichoski, U.; Yang, L.; Yen, Y.-R.; Zhao, Y. B.; nEXO Collaboration

    2015-02-01

    Progress on a method of barium tagging for the nEXO double beta decay experiment is reported. Absorption and emission spectra for deposits of barium atoms and ions in solid xenon matrices are presented. Excitation spectra for prominent emission lines, temperature dependence, and bleaching of the fluorescence reveal the existence of different matrix sites. A regular series of sharp lines observed in Ba+ deposits is identified with some type of barium hydride molecule. Lower limits for the fluorescence quantum efficiency of the principal Ba emission transition are reported. Under current conditions, an image of fewer than or equal to 104 Ba atoms can be obtained. Prospects for imaging single Ba atoms in solid xenon are discussed.

  17. Hadamard speckle contrast reduction

    NASA Astrophysics Data System (ADS)

    Trisnadi, Jahja I.

    2004-01-01

    The condition for a diffuser to produce the maximum speckle contrast reduction with the minimum number of distinct phase patterns is derived. A binary realization of this optimum diffuser is obtained by mapping the rows or columns of a Hadamard matrix to the phase patterns. The method is experimentally verified in the Grating Light Valve laser projection display.

  18. Phonation in Tonal Contrasts

    ERIC Educational Resources Information Center

    Kuang, Jianjing

    2013-01-01

    Phonation is used in many tonal languages, but how it should be incorporated into tonal systems is not well understood. The purpose of this dissertation thus is to examine the role of phonation in tonal contrasts, and to investigate how phonation and pitch interact in the tonal space. This dissertation presents close studies of tonal contrasts…

  19. Flashing anomalous color contrast.

    PubMed

    Pinna, Baingio; Spillmann, Lothar; Werner, John S

    2004-01-01

    A new visual phenomenon that we call flashing anomalous color contrast is described. This phenomenon arises from the interaction between a gray central disk and a chromatic annulus surrounded by black radial lines. In an array of such figures, the central gray disk no longer appears gray, but assumes a color complementary to that of the surrounding annulus. The induced color appears: (1) vivid and saturated; (2) self-luminous, not a surface property; (3) flashing with eye or stimulus movement; (4) floating out of its confines; and (5) stronger in extrafoveal than in foveal vision. The strength of the effect depends on the number, length, width, and luminance contrast of the radial lines. The results suggest that the chromatic ring bounding the inner tips of the black radial lines induces simultaneous color contrast, whereas the radial lines elicit, in conjunction with the gray disk and the ring, the flashing, vividness, and high saturation of the effect. The stimulus properties inducing the illusion suggest that flashing anomalous color contrast may be based on asynchronous interactions among multiple visual pathways. PMID:15518215

  20. Barium hydrogen phosphate/gelatin composites versus gelatin-free barium hydrogen phosphate: synthesis and characterization of properties.

    PubMed

    Gashti, Mazeyar Parvinzadeh; Burgener, Matthias; Stir, Manuela; Hulliger, Jürg

    2014-10-01

    Recently, attention has been spent on crystal growth of phosphate compounds in gels for studying the mechanism of in vitro crystallization processes. Here, we present a gel-based approach for the synthesis of barium hydrogen phosphate (BHP) crystals using single and double diffusion techniques in gelatin. The composite crystals were compared with analytical grade BHP powder, single and polycrystalline BHP materials using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), scanning pyroelectric microscopy (SPEM), optical microscopy (OM), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). FTIR spectra showed surface adsorption of gelatin molecules by using BHP stacked sheets due to CH2 stretching, CH2 bending and amide I vibrations are found in a gelatin content of about 2% determined by dissolution. SEM shows various crystal morphologies of the BHP/gelatin composites forming bundled micro-flakes to irregular bundled needles and spheres different from gel-free crystals. The variety in morphology depends on the ion concentration, pH of gel as well as the method of crystal growth. SPEM investigation of BHP/gelatin aggregates revealed polar domains showing alteration of the polarization. Moreover, BHP/gelatin composite crystals showed a higher thermal stability in comparison with analytical grade BHP or/and BHP single crystals due to strong interactions between gelatin and BHP. The XRD diffraction analysis demonstrated that the single and double diffusion techniques in gelatin led to the formation of orthorhombic BHP. This study demonstrates that gelatin is a useful high molecular weight biomacromolecule for controlling the crystallization of a composite material by producing a variety of morphological forms. PMID:24996024

  1. Feasibility and usefulness of using swallow contrast-enhanced ultrasound to diagnose Zenker's diverticulum: preliminary results.

    PubMed

    Cui, Xin-Wu; Ignee, Andre; Baum, Ulrich; Dietrich, Christoph F

    2015-04-01

    Zenker's diverticulum (ZD) may be misdiagnosed on conventional ultrasound as a thyroid nodule or other lesion. A barium esophagram is usually used to confirm the diagnosis; however, this procedure exposes the patient to radiation. The aim of this study was to evaluate the feasibility of using swallow contrast-enhanced ultrasound (swallow-CEUS) to diagnose ZD. Ten consecutive patients with ZD (7 men and 3 women, aged 67 ± 11 y) were included in the study. In 4 patients, ZD was incidentally found on head and neck ultrasound, and in 6 patients, ZD was suspected because of dysphagia. All lesions could be detected on conventional ultrasound before swallow-CEUS. Ten healthy volunteers (8 men and 2 women, aged 60 ± 12 y) were chosen as a control group. Written informed consent was obtained. With the patient in the sitting or upright position, conventional ultrasound was performed first to image the lesion, then the patient was asked to swallow ultrasound contrast agent (UCA) (2-4 drops of SonoVue diluted with about 200 mL of tap water). Transity of the contrast agent in the esophagus was imaged with CEUS. Retention of the UCA in the diverticulum was monitored for at least 3 min. All patients underwent a barium esophagram as the gold standard. Swallow-CEUS revealed that in all patients (100%), the UCA was transported from the pharynx to the esophagus while the patient swallowed. ZD appeared as a pouch-shaped structure at the posterior pharyngo-esophageal junction that retained UCA longer than 3 min. The barium esophagram confirmed the diagnosis of ZD in all patients. For the 10 volunteers, no abnormal structure (retaining UCA) was detected during or after swallowing of UCA. With the advantages of no radiation and bedside availability, swallow-CEUS may become a method of choice in confirmation of the diagnosis of ZD, especially when ZD is suspected on conventional ultrasound. PMID:25701519

  2. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, dust, ... a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  3. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  4. Meteorological support to the West German-United States Barium Ion Cloud Project.

    NASA Technical Reports Server (NTRS)

    Westfall, R. R.; Chamberlain, L. W.

    1972-01-01

    The objective of the Barium Ion Cloud Project was to study a barium ionized cloud released at an altitude of 5 earth radii. Accurate forecasting of weather conditions to prevail during the experiment period was critical to the project success. Good seeing conditions were required at all optical sites during the experiment. All meteorological support was the responsibility of the National Weather Service at Wallops Station, Virginia. Preliminary results confirm the scientists' theories of the magnetic fields and the existence of electric fields in the magnetosphere.

  5. Physical states and properties of barium titanate films in a plane electric field

    NASA Astrophysics Data System (ADS)

    Shirokov, V. B.; Kalinchuk, V. V.; Shakhovoi, R. A.; Yuzyuk, Yu. I.

    2016-07-01

    The influence of a plane electric field on the phase states of barium titanate thin films under the conditions of forced deformation has been studied. The field dependence of a complete set of material constants has been taken in the region of the c-phase, where polarization losses are absent. The material constants are calculated using equations of the piezoelectric effect derived by linearizing the nonlinear equations of state from the phenomenological; theory for barium titanate. It has been shown that there is a critical value of the field at which the electromechanical coupling coefficient reaches a maximum.

  6. The structural properties of barium cobalt hexaferrite powder prepared by a simple heat treatment method

    NASA Astrophysics Data System (ADS)

    Chauhan, Chetna; Jotania, Rajshree

    2016-05-01

    The W-type barium hexaferrite was prepared using a simple heat treatment method. The precursor was calcinated at 650°C for 3 hours and then slowly cooled to room temperature in order to obtain barium cobalt hexaferrite powder. The prepared powder was characterised by different experimental techniques like XRD, FTIR and SEM. The X-ray diffractogram of the sample shows W-and M phases. The particle size calculated by Debye Scherrer formula. The FTIR spectra of the sample was taken at room temperature by using KBr pallet method which confirms the formation of hexaferrite phase. The morphological study on the hexaferrite powder was carried out by SEM analysis.

  7. Calcium barium niobate as a functional material for broadband optical frequency conversion.

    PubMed

    Sheng, Yan; Chen, Xin; Lukasiewicz, Tadeusz; Swirkowicz, Marek; Koynov, Kaloian; Krolikowski, Wieslaw

    2014-03-15

    We demonstrate the application of as-grown calcium barium niobate (CBN) crystal with random-sized ferroelectric domains as a broadband frequency converter. The frequency conversion process is similar to broadband harmonic generation in commonly used strontium barium niobate (SBN) crystal, but results in higher conversion efficiency reflecting a larger effective nonlinear coefficient of the CBN crystal. We also analyzed the polarization properties of the emitted radiation and determined the ratio of d32 and d33 components of the second-order susceptibility tensor of the CBN crystal. PMID:24690779

  8. Magnetic properties of barium ferrite dispersed within polystyrene-butadiene-styrene block copolymers.

    PubMed

    Chipara, M; Skomski, R; Ali, N; Hui, D; Sellmyer, D J

    2009-06-01

    Magnetic properties of nanocomposite materials obtained by dispersing barium ferrite nanoparticles within polystyrene-butadiene-styrene block copolymer, in the temperature range, 300 to 500 K are reported. The temperature dependence of the magnetization at saturation, averaged uniaxial magnetocrystalline anisotropy, and coercive field of thick films are analyzed. A "matrix effect" was noticed within the glass transition range of the hard component (polystyrene) of the polymeric matrix. The reported modifications of the magnetic properties were assigned to the competition between the magnetic and mechanical reorientation of nanoparticles within the polymeric matrix. Such modifications were not observed in barium ferrite dispersed in cement. PMID:19504902

  9. ION-EXCHANGE METHOD FOR SEPARATING RADIUM FROM RADIUM-BARIUM MIXTURES

    DOEpatents

    Fuentevilla, M.E.

    1959-06-30

    An improved process is presented for separating radium from an aqueous feed solution containing radium and barium values and a complexing agent for these metals. In this process a feed solutlon containing radium and barium ions and a complexing agent for said ions ls cycled through an exchange zone in resins. The radiumenriched resin is then stripped of radium values to form a regeneration liquid, a portion of which is collected as an enriched product, the remaining portion being recycled to the exchange zone to further enrich the ion exchange resin in radium.

  10. Physical Property of Magnesium Doped Barium Hexaferrite Particles By Citrate Precursor Route In Presence Of Surfactants

    SciTech Connect

    Paladiya, Snehal; Chauhan, C. C.; Jotania, R. B.

    2010-12-01

    M-type Barium Magnesium hexaferrite with the composition BaMg{sub 2}Fe{sub 10}O{sub 19} was successfully prepared with and without surfactant by using a citrate precursor route. The obtained precursors were calcined at various temperatures. The crystalline structure, phase analysis and particle size were investigated by using X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) techniques. It is observed that the surfactant addition controls the microstructure of the formed Barium Magnesium hexaferrite particles and the type of surfactant plays a crucial role in deciding the morphology of particles.

  11. Measuring contrast sensitivity

    PubMed Central

    Pelli, Denis G.; Bex, Peter

    2013-01-01

    Contrast sensitivity defines the threshold between the visible and invisible, which has obvious significance for basic and clinical vision science. Fechner's 1860 review reported that threshold contrast is 1% for a remarkably wide range of targets and conditions. While printed charts are still in use, computer testing is becoming more popular because it offers efficient adaptive measurement of threshold for a wide range of stimuli. Both basic and clinical studies usually want to know fundamental visual capability, regardless of the observer's subjective criterion. Criterion effects are minimized by the use of an objective task: multiple-alternative forced-choice detection or identification. Having many alternatives reduces the guessing rate, which makes each trial more informative, so fewer trials are needed. Finally, populations who may experience crowding or target confusion should be tested with one target at a time. PMID:23643905

  12. Rapid ray motions in barium plasma clouds and auroras

    SciTech Connect

    Wescott, E.M.; Hallinan, T.J.; Stenbaek-Nielsen, H.C.; Swift, D.W.; Wallis, D.D. )

    1993-03-01

    Barium plasma clouds released at high latitudes characteristically become striated with many field-aligned rays. The rays which often resemble auroral features usually drift as a whole with the E [times] B/B[sup 2] drift of the cloud and alter position only slowly (order or tens of seconds). On two evenings in 1968, in releases from Andoya, Norway, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly (10-20 km/s) through three different Ba[sup +] clouds. Similar effects were observed in Ba[sup +] clouds released from rockets launched from Poker Flat, Alaska: On March 21, 1973, in two Ba thermite releases and on March 22, 1980, in the Ba-shaped charge experiment Miss Peggy.' On these occasions, auroras on or near the Ba[sup +] L shell, also exhibited active rapid ray motions. This leads to the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba[sup +] clouds would lead to a better understanding of the physics of auroral ray motions and the auroral ionosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. Direct motion of an isolated Ba[sup +] ray past the other rays by E [times] B/B[sup 2] motion seems very unlikely due to the observed variations in the enhancements and the large E field required (> 500 mV/m). Compressional waves do not seem to be of sufficient amplitude or velocity. Absorption or radiation of Doppler shifted Ba[sup +] emissions by ions gyrating or moving at a few kilometers per second seems to be the most promising mechanism for producing the enhancements. The observations provide compelling evidence for the existence of transient electric fields of order 100 mV/m at altitudes as low as 200 km during active aurora with rapid ray motions. The affected regions have dimensions of order a few kilometers across B and move eastward at 10-20 km/s. 36 refs., 10 figs., 1 tab.

  13. Chromatography: concepts and contrasts

    SciTech Connect

    Miller, J.M.

    1988-01-01

    As the author states in the Preface, this text attempts to provide a unified approach to chromatography (hence the title) by way of contrasting similarities and differences between gas chromatography (GC), column liquid chromatography (LC), and thin-layer chromatography (TLC). This book is also said to be pitched at an elementary level, suitable for most newcomers to the field (e.g., advanced undergraduates and beginning graduate students in the academic world, as well as bench-level chemists in industry).

  14. Stereopsis from contrast envelopes.

    PubMed

    Langley, K; Fleet, D J; Hibbard, P B

    1999-07-01

    We report two experiments concerning the site of the principal nonlinearity in second-order stereopsis. The first exploits the asymmetry in perceiving transparency with second-order stimuli found by Langley et al. (1998) (Proceedings of the Royal Society of London B, 265, 1837-1845) i.e. the product of a positive-valued contrast envelope and a mean-zero carrier grating can be seen transparently only when the disparities are consistent with the envelope appearing in front of the carrier. We measured the energy at the envelope frequencies that must be added in order to negate this asymmetry. We report that this amplitude can be predicted from the envelope sidebands and not from the magnitude of compressive pre-cortical nonlinearities measured by other researchers. In the second experiment, contrast threshold elevations were measured for the discrimination of envelope disparities following adaptation to sinusoidal gratings. It is reported that perception of the envelope's depth was affected most when the adapting grating was similar (in orientation and frequency) to the carrier, rather than to the contrast envelope. These results suggest that the principal nonlinearity in second-order stereopsis is cortical, occurring after orientation- and frequency-selective linear filtering. PMID:10367053

  15. Polychromatic diffraction contrast tomography

    SciTech Connect

    King, A.; Reischig, P.; Adrien, J.; Peetermans, S.; Ludwig, W.

    2014-11-15

    This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented.

  16. Regeneration of barium carbonate from barium sulphide in a pilot-scale bubbling column reactor and utilization for acid mine drainage.

    PubMed

    Mulopo, J; Zvimba, J N; Swanepoel, H; Bologo, L T; Maree, J

    2012-01-01

    Batch regeneration of barium carbonate (BaCO(3)) from barium sulphide (BaS) slurries by passing CO(2) gas into a pilot-scale bubbling column reactor under ambient conditions was used to assess the technical feasibility of BaCO(3) recovery in the Alkali Barium Calcium (ABC) desalination process and its use for sulphate removal from high sulphate Acid Mine Drainage (AMD). The effect of key process parameters, such as BaS slurry concentration and CO(2) flow rate on the carbonation, as well as the extent of sulphate removal from AMD using the recovered BaCO(3) were investigated. It was observed that the carbonation reaction rate for BaCO(3) regeneration in a bubbling column reactor significantly increased with increase in carbon dioxide (CO(2)) flow rate whereas the BaS slurry content within the range 5-10% slurry content did not significantly affect the carbonation rate. The CO(2) flow rate also had an impact on the BaCO(3) morphology. The BaCO(3) recovered from the pilot-scale bubbling column reactor demonstrated effective sulphate removal ability during AMD treatment compared with commercial BaCO(3). PMID:22233912

  17. Phase contrast portal imaging using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Umetani, K.; Kondoh, T.

    2014-07-01

    Microbeam radiation therapy is an experimental form of radiation treatment with great potential to improve the treatment of many types of cancer. We applied a synchrotron radiation phase contrast technique to portal imaging to improve targeting accuracy for microbeam radiation therapy in experiments using small animals. An X-ray imaging detector was installed 6.0 m downstream from an object to produce a high-contrast edge enhancement effect in propagation-based phase contrast imaging. Images of a mouse head sample were obtained using therapeutic white synchrotron radiation with a mean beam energy of 130 keV. Compared to conventional portal images, remarkably clear images of bones surrounding the cerebrum were acquired in an air environment for positioning brain lesions with respect to the skull structure without confusion with overlapping surface structures.

  18. Phase contrast portal imaging using synchrotron radiation

    SciTech Connect

    Umetani, K.; Kondoh, T.

    2014-07-15

    Microbeam radiation therapy is an experimental form of radiation treatment with great potential to improve the treatment of many types of cancer. We applied a synchrotron radiation phase contrast technique to portal imaging to improve targeting accuracy for microbeam radiation therapy in experiments using small animals. An X-ray imaging detector was installed 6.0 m downstream from an object to produce a high-contrast edge enhancement effect in propagation-based phase contrast imaging. Images of a mouse head sample were obtained using therapeutic white synchrotron radiation with a mean beam energy of 130 keV. Compared to conventional portal images, remarkably clear images of bones surrounding the cerebrum were acquired in an air environment for positioning brain lesions with respect to the skull structure without confusion with overlapping surface structures.

  19. [Contrast media: present status and future of their production and use].

    PubMed

    Tsyb, A F; Sergeev, P V; Amosov, I S; Nikitina, R G; Shanazarov, K S; Shimanovskiĭ, N L; Degtiarev, V A

    1989-01-01

    Analysis of the problems involving the design and application of Soviet-made radiocontrast agents showed that the synthesis of such drugs as Iodamid, Triombrast, Etiotrast, Bilimin, and Bilignost in this country made it possible to eliminate the arrears in this field. Together with the elaboration of topics concerning the pharmacokinetics and adverse effects of the above contrast agents, this helped to create a sound scientific base for further work on the unsolved problems, primarily, (1) to synthesize Soviet non-ionogenic radiocontrast agents; (2) to prepare and introduce Soviet ultrasonographic contrast agents into practice; (3) to prepare and introduce magnetic resonance contrast ones into practice; and (4) to introduce unique radiocontrast agents such as triombrast as oil emulsion, oleoferrotrast, fine-dispersion barium sulphate, and chromoetiotrast into clinical practice and to set up their production. PMID:2683464

  20. A contribution to the discussion on the safety of air weapons.

    PubMed

    Wightman, G; Cochrane, R; Gray, R A; Linton, M

    2013-09-01

    differentiate phases. A barium salt paste was applied to outer surfaces and iodine solution or barium nitrate solution containing red food colouring was injected into the pellet track to enhance the contrast of the track. The track through the gelatin tended to enclose itself whereas the track through the organ remained more open, presumably due to the inhomogeneity of the fibrous nature of the tissue. Pellets were also fired at construction materials (wood, plasterboard and brick) and computed tomography used to determine the volume of damage created. Pellets perforated single layers of wood and plasterboard and would embed in a second layer. However, if the two layers were in contact the pellet did not penetrate the first layer. An air rifle pellet could therefore perforate house construction materials, although the resultant kinetic energy would be low and further damage would be limited. Some of the possible physical parameters are discussed that might help predict the degree of damage caused, but from this study it is not possible to define a limit which could be proposed as safe. PMID:23937945

  1. Barium responsiveness of the rat aorta and femoral artery during pregnancy.

    PubMed

    Hart, J L

    1982-01-11

    The barium responses of isolated aortic strips and femoral arteries from non-pregnant and pregnant rats were investigated. Barium caused concentration-related increases in tension of vessels from both pregnant and non-pregnant rats. The concentration-response curves of femoral arteries from non-pregnant and 3 week pregnant rats were not different; however contractility and slopes of concentration-response lines for thoracic aortas from 1, 2 and 3 week pregnant rats were significantly less than those of aortas from non-pregnant rats. In addition, barium caused rhythmic contractions to develop in both femoral arteries and aortas of 3 week pregnant rats more frequently than vessels from non-pregnant rats. Rhythmic contractions did not develop in aortas from 3 week pregnant rats in calcium-free Krebs. Since the effects of barium on the electrical and mechanical activity of various muscles have been postulated to be similar to and/or dependent on calcium, these results may indicate that changes in calcium sensitivity of vascular smooth muscle occur during pregnancy. Such changes may contribute to the blood flow redistribution and other cardiovascular adaptations of pregnancy. PMID:7054642

  2. [Mesenteric panniculitis of the colon: barium enema, US, CT, and MRI findings (case report)].

    PubMed

    Kebapçi, Mahmut; Adapinar, Baki; Kaya, Tamer; Kebapçi, Nur

    2004-12-01

    Mesenteric panniculitis as an uncommon disease of unknown etiology characterised by nonspecific inflammation of the fat tissue of the mesentery. In this report, we are presenting a case of mesenteric panniculitis of the rectosigmoid colon in which characteristic findings of barium enema, ultrasonography, computed tomography, and magnetic resonance imaging were noted. We emphasized the diagnostic significance of these methods. PMID:15611917

  3. Effects of barium and cadmium on the population development of the marine nematode Rhabditis (Pellioditis) marina.

    PubMed

    Lira, V F; Santos, G A P; Derycke, S; Larrazabal, M E L; Fonsêca-Genevois, V G; Moens, T

    2011-10-01

    Offshore oil and gas drilling often involves the use of fluids containing barium and traces of other heavy metals. These may affect the environment, but information on their toxicity to benthic biota remains scant. Here, we present results of a 10-day bioassay with the marine nematode Rhabditis (Pellioditis) marina at different loads of barium (0-10 ,000 ppm nominal concentrations) and cadmium (0-12 ppm) in the range of concentrations reported from drilling-impacted sediments. Barium did not affect the fitness and population development of R. (P.) marina at concentrations up to 300 ppm, but did cause a decrease in population abundance and an increase in development time from concentrations of 400-2000 ppm onwards. Increased mortality occurred at 4800 ppm Ba. For cadmium, LOEC and EC₅₀ values for total population abundance were 2.95 and 8.82 ppm, respectively. Cd concentrations as low as 2.40 to 2.68 caused a decrease in the abundance of adult nematodes, indicating that assays covering more generations would likely demonstrate yet more pronounced population-level effects. Our results indicate that oil and gas drilling activities may potentially have important implications for the meiobenthos through the toxicity of barium and associated metals like cadmium. PMID:21855994

  4. Low temperature phase barium borate: A new optical limiter in continuous wave and nano pulsed regime

    NASA Astrophysics Data System (ADS)

    Babeela, C.; Girisun, T. C. Sabari

    2015-11-01

    Low temperature phase barium borate was synthesized by hydrothermal method. XRD analysis confirms the formation of γ-BBO or hydrated barium polyborate (Ba3B6O9(OH)6) which crystallizes in monoclinic system in the P2/c space group. The molecular structure analysis shows the presence of dominant BO4 unit and the hydrated nature of material. γ-BBO exhibits sharp absorption edge at 202 nm and highly transparency in the UV-Visible-NIR region. The peak at 347 nm in the emission spectrum is due to the presence of self-trapped exciton. The third order nonlinear optical properties and limiting behavior of low temperature barium borate in both pulsed and continuous wave regime were studied. The effective 2PA absorption coefficient of γ-BBO under ns pulse excitation is estimated to be 0.38 × 10-10 m/W. The nonlinear absorption coefficient, refractive index and optical susceptibility of the material in cw regime were found to be in the order of 10-5 m W-1, 10-12 m2 W-1, 10-6 esu respectively. In both regimes, low temperature phase barium borate exhibits better optical limiting properties than high temperature phase β-BBO.

  5. Effect of aluminum substitution on microwave absorption properties of barium hexaferrite

    NASA Astrophysics Data System (ADS)

    Qiu, Jianxun; Zhang, Qiguo; Gu, Mingyuan; Shen, Haigen

    2005-11-01

    Aluminum substituted barium hexaferrites were prepared by the self-propagating combustion method and subsequent calcination at 850 °C. The crystalline structure, complex permittivity, complex permeability, and hyperfine parameters of BaFe12-xAlxO19 (x varies from 1.5 to 2.3 in steps of 0.2) were measured with x-ray diffraction (XRD), vector network analyzer and Mössbauer spectroscopy. The XRD results show that all Al3+ ions enter into the lattice of hexagonal barium ferrite. The substitution of Al3+ ions can greatly affect the complex permittivity and permeability of barium ferrite. With increasing substitution, the real part of complex permittivity increases gradually, and the peaks of the imaginary part of complex permeability shift into higher frequency band. When the substitution amount x is 1.9, the largest movement of the peaks is 1.95 GHz, which indicates that the ferromagnetic resonant frequency of barium ferrite increases by 1.95 GHz. The Al3+ ions preferentially occupy the 4f2, 2a, 4f1, and 12k sites in the subcrystalline structure up to x =1.9, and then the Al3+ ions mainly occupy 12k sites. This change also results in 2b sites with a large quadrupole splitting. These occupations lead to a variable magnetocrystalline anisotropy field.

  6. Near-resonance-Rayleigh scattering measurement on a resonant laser-driven barium plasma

    SciTech Connect

    Nee, T.A.

    1985-06-01

    Near-resonance-Rayleigh scattering is used as a space-time-resolved density probe on a resonant laser-driven barium plasma. Feasibility of this technique was investigated. Comparison to other methods such as absorption technique is made and found to be consistent.

  7. Distribution and source of barium in ground water at Cattaraugus Indian Reservation, southwestern New York

    USGS Publications Warehouse

    Moore, R.B.; Staubitz, W.W.

    1984-01-01

    High concentrations of dissolved barium have been found in ground water from bedrock wells on the Seneca Nation of Indians Reservation on Cattaraugus Creek in southwestern New York. Concentrations in 1982 were as high as 23.0 milligrams per liter , the highest found reported from any natural ground-water system in the world. The highest concentrations are in a bedrock aquifer and in small lenses of saturated gravel between bedrock and the overlying till. The bedrock aquifer is partly confined by silt, clay, and till. The high barium concentrations are attributed to dissolution of the mineral barite (BaSO4), which is present in the bedrock and possibly in overlying silt, clay, or till. The dissolution of barite seems to be controlled by action of sulfate-reducing bacteria, which alter the BaSO4 equilibrium by removing sulfate ions and permitting additional barite to dissolve. Ground water from the surficial, unconsolidated deposits and surface water in streams contain little or no barium. Because barium is chemically similar to calcium, it probably could be removed by cation exchange or treatments similar to those used for water softening. (USGS)

  8. Thermochemical process for the production of hydrogen using chromium and barium compound

    DOEpatents

    Bamberger, Carlos E.; Richardson, Donald M.

    1977-01-25

    Hydrogen is produced by a closed cyclic process involving the reduction and oxidation of chromium compounds by barium hydroxide and the hydrolytic disproportionation of Ba.sub.2 CrO.sub.4 and Ba.sub.3 (CrO.sub.4).sub.2.

  9. Barium versus Nonbarium Stimuli: Differences in Taste Intensity, Chemesthesis, and Swallowing Behavior in Healthy Adult Women

    ERIC Educational Resources Information Center

    Nagy, Ahmed; Steele, Catriona M.; Pelletier, Cathy A.

    2014-01-01

    Purpose: The authors examined the impact of barium on the perceived taste intensity of 7 different liquid tastant stimuli and the modulatory effect that these differences in perceived taste intensity have on swallowing behaviors. Method: Participants were 80 healthy women, stratified by age group (<40; >60) and genetic taste status…

  10. Assessment of Barium Sulphate Formation and Inhibition at Surfaces with Synchrotron X-ray Diffraction (SXRD)

    SciTech Connect

    E Mavredaki; A Neville; K Sorbie

    2011-12-31

    The precipitation of barium sulphate from aqueous supersaturated solutions is a well-known problem in the oil industry often referred to as 'scaling'. The formation and growth of barite on surfaces during the oil extraction process can result in malfunctions within the oil facilities and serious damage to the equipment. The formation of barium sulphate at surfaces remains an important topic of research with the focus being on understanding the mechanisms of formation and means of control. In situ synchrotron X-ray diffraction (SXRD) was used to investigate the formation of barium sulphate on a stainless steel surface. The effect of Poly-phosphinocarboxylic acid (PPCA) and Diethylenetriamine-penta-methylenephosphonic acid (DETPMP) which are two commercial inhibitors for barium sulphate was examined. The in situ SXRD measurements allowed the identification of the crystal faces of the deposited barite in the absence and presence of the two inhibitors. The preferential effect of the inhibitors on some crystal planes is reported and the practical significance discussed.

  11. Fabrication and characterization of cerium doped barium titanate/PMMA nanocomposites

    NASA Astrophysics Data System (ADS)

    Padalia, Diwakar; Bisht, Garima; Johri, U. C.; Asokan, K.

    2013-05-01

    The cerium doped barium titanate (BaTiO3:Ce)/poly methyl methacrylate(PMMA) polymer nano-composites (PNC) were successfully fabricated via solvent evaporation method with microwaves (2.4 GHz) heating. The X-ray diffraction measurements confirm the formation of barium titanate (BT) with crystallite size ranges from 55 to 62 nm. Differential scanning calorimetry study shows that the glass transition temperature (Tg) directly affected by microwaves heat treatment and particle size of filler. The broadband dielectric spectroscopy was employed to investigate the frequency and temperature dependence of the dielectric properties of the nanocomposites in a frequency range from 75 kHz to 5 MHz and temperature range 80-400 K. The introduction of different BT fillers in PMMA enhance the dielectric constant of PNCs drastically and give a smooth response in frequency range mentioned above. The loss factor of the composite can be suppressed by using cerium doped barium titanate filler rather than pure barium titanate filler.

  12. BARIUM BIOAVAILABILITY AS THE CHLORIDE, SULFATE, OR CARBONATE SALT IN THE RAT

    EPA Science Inventory

    This study was conducted to determine how the bioavailability of a low concentration of barium (Ba) in drinking water is affected by anion speciation. Male Sprague Dawley rats weighing 250-300 grams were maintained on a diet of less than 1 mg Ba/kg of food for at least 1 month pr...

  13. WEAK-ACID ION EXCHANGE FOR REMOVING BARIUM, RADIUM, AND HARDNESS

    EPA Science Inventory

    Weak-acid resin in the hydrogen form was found to effectively remove barium, radium, and hardness, without increasing the sodium content of the product water. The maximum capacity of the weak-acid resin was about 2.3 times that of strong-acid resin, and much less spent regenerant...

  14. PROPOSED ORAL REFERENCE DOSE (RFD) FOR BARIUM AND COMPOUNDS (Final Report) 2004

    EPA Science Inventory

    This document is the final report for the 2004 external peer review of the Proposed Oral Reference Dose (RfD) for Barium and Compounds, prepared by the U.S. Environmental Protection Agency (EPA), National Center for Environmental Assessment (NCEA), for the Integrated Risk Informa...

  15. Periodate salts as pyrotechnic oxidizers: development of barium- and perchlorate-free incendiary formulations.

    PubMed

    Moretti, Jared D; Sabatini, Jesse J; Chen, Gary

    2012-07-01

    In a flash: pyrotechnic incendiary formulations with good stabilities toward various ignition stimuli have been developed without the need for barium or perchlorate oxidizers. KIO(4) and NaIO(4) were introduced as pyrotechnic oxidizers and exhibited excellent pyrotechnic performance. The periodate salts may garner widespread use in military and civilian fireworks because of their low hygroscopicities and high chemical reactivities. PMID:22639415

  16. Effect of annealing in a reductive environment on the magnetic properties of barium ferrite nanoparticles doped with Ti4+ and Co2+

    NASA Astrophysics Data System (ADS)

    Petinov, V. I.

    2011-10-01

    It was found experimentally that the annealing of BaFe10.6Co0.7Ti0.7O19 and BaFe10.2Co0.9Ti0.9O19 complex magnetic oxide nanoparticles in paraffin vapor irreversibly increases their coercive force H c and saturation magnetization M s to the H c and M s values for barium ferrite BaFe12O19. The annealing of these nanoparticles, and of particles of magnetic oxides CrO2, γ-Fe2O3, and BaFe12O19 in air and in paraffin vapor, has not been shown to affect their H c and M s values. An explanation in terms of diffusion self-purification of nanoparticles from ion impurities activated by chemical processes on their surface is offered.

  17. Cathodic arc deposition of barium oxide for oxide-coated cathodes

    SciTech Connect

    Umstattd, R.; Pi, T.; Luhmann, N. Jr.; Scheitrum, G.; Monteiro, O.; Brown, I.

    1998-12-31

    Cathodic arc deposition is used to create a barium oxide plasma which is then deposited/implanted onto a cathode nickel substrate. The primary motivation for this work is the critical need for a reliable, repeatable thermionic cathode for the production of high power, microsecond duration microwave pulses. The deposition is performed by generating a cathodic arc discharge at the surface of a barium of barium-strontium alloy rod. The metal plasma thus created is deposited onto the target in the presence of small amounts of oxygen. Difficulties in handling the highly hygroscopic barium and strontium sources were addressed by encapsulating the source rods in thin nickel sleeves (nickel being the major constituent of the deposition target). Both filtered and unfiltered depositions were performed; the former in the interest of improving film quality and the latter in an effort to improve deposition rate. The plasma deposition is monitored via a rate thickness monitor, an optical emission spectrometer for plasma composition information, and an electrostatic probe for the density and temperature profile of the plasma. Good film adhesion is critical for oxide cathodes since they are continually cycled, this, substrates are pulse biased during deposition to encourage implantation. An initial test was performed in which a film of barium oxide approximately one micron in thickness was deposited onto a small section of a 1 in. diameter nickel cathode with better than expected mission results. These preliminary results will be presented together with the results from follow-up experiments done to improve overall coating quality and emission performance.

  18. On Establishing Underlying Tonal Contrast

    ERIC Educational Resources Information Center

    Snider, Keith

    2014-01-01

    Phonological field work is largely about establishing contrast in comparable environments. The notion of phonological contrast, however, can be confusing, particularly in its application to tone analysis. Does it mean phonemic contrast in the structuralist sense, or does it mean underlying contrast in the generative sense? Many linguists, in…

  19. Air Pollution Surveillance Systems

    ERIC Educational Resources Information Center

    Morgan, George B.; And Others

    1970-01-01

    Describes atmospheric data monitoring as part of total airpollution control effort. Summarizes types of gaseous, liquid and solid pollutants and their sources; contrast between urban and rural environmental air quality; instrumentation to identify pollutants; and anticipated new non-wet chemical physical and physiochemical techniques tor cetection…

  20. Modeling of compositionally graded barium strontium titanate from first principles

    NASA Astrophysics Data System (ADS)

    Walizer, Laura Elizabeth

    Barium Strontium Titanate (BaxSr1-xTiO 3 or BST) is a Perovskite alloy of interest for both technological and intellectual reasons. Its ferroelectric and piezoelectric properties make it useful in a variety of electric components such as transducers and actuators, and BST in particular is a material of interest for the development of a ferroelectric RAM for computers.(1) The inclusion of SrTiO3, an incipient ferroelectric, and the fact that the properties of a BST system depend strongly on its relative composition of BaTiO3 (BT) and SrTiO3 (ST), make also this a material of high interest. (2) Compositionally graded systems are of further interest (see e.g., Refs. (3), (4), (5) and references therein), partly because their compositional grading leads to a built-in polarization gradient. Due to this, these systems could act as transcapacitors, devices which act as charge amplifiers in much the same way that transistors act as current amplifiers.(3), (4) Here, compositionally graded BST systems were modeled using a first-principles derived effective Hamiltonian method within Monte-Carlo simulation. (6) The graded systems under consideration had an average Ba composition of 70%. These systems were modeled under stress-free conditions, as well as, under epitaxial strain due to a SrTiO3 substrate. Both the degree of grading and the thickness of the layers were varied. The investigation revealed that graded BST systems behaved differently from bulk BST systems in several ways. First, some graded BST systems possessed both monodomain states qualitatively similar to those found in bulk systems (except that the polarization exhibited a "wave" behavior inside the graded systems), and also states with domain striping. Where this occurred, the monodomain state was lower in energy, and was therefore the ground-state, but the striped domain state was found to be metastable, representing a local energy minimum. Analyzing unstrained compositionally graded systems layer by layer

  1. Air Abrasion

    MedlinePlus

    ... delivered directly to your desktop! more... What Is Air Abrasion? Article Chapters What Is Air Abrasion? What Happens? The Pros and Cons Will I Feel Anything? Is Air Abrasion for Everyone? print full article print this ...

  2. Differential interference contrast tomography.

    PubMed

    Vishnyakov, Gennady; Levin, Gennady; Minaev, Vladimir; Latushko, Mikhail; Nekrasov, Nikolay; Pickalov, Valery

    2016-07-01

    We present a new approach to optical tomography of phase objects that is referred to as differential interference contrast tomography (DICT). The main feature of DICT is that the result of tomographic reconstruction is a 3D DIC image. This image is described by partial derivative of 3D refractive index distribution in one direction. The DICT setup consists of a lateral shearing phase-shifting interference microscope with low-coherent LED illumination. To create projections of the sample at various illumination angles, an angular scanning beam was used. 3D DIC tomograms of a white blood cell are presented. The comparison between the reconstructed DIC tomogram slices and the conventional DIC images of the same sample at the same depths are also represented. PMID:27367095

  3. Polarization contrast vision

    NASA Astrophysics Data System (ADS)

    Pugh, Edward N.

    1990-05-01

    An attempt is made to establish the possibility that the geometry of certain classes of vertebrate photoreceptors results in a birefringence that allows the animals to utilize the state of polarization of light striking their retinas as a meaningful stimulus parameter. Simulate the photoreceptors as dielectric waveguides using a simple physical model, and augment this theoretical work with empirical measurements of the light guiding properties of photoreceptors in isolated pieces of retina from a green sunfish (Lepomis cyanellus). With a classical conditioning paradigm, this fish's sensitivity to light is modulated by the orientation of the plane of polarization of linearly polarized light. This functional dependence was predicted by a hypothetical antagonistic mechanism between twin cones of two orientations in the animal's retinal mosaic. Further study is planned for the nature of the stimulus to which the fish is sensitive by creating a camera that will generate images based purely upon the contrast between orthogonal polarizations at each point in space.

  4. Contrast echocardiography 1996. A review.

    PubMed Central

    Villarraga, H R; Foley, D A; Mulvagh, S L

    1996-01-01

    Remarkable advances in the field of contrast echocardiography have been made during the last decade. Interest in ultrasound contrast agents that strengthen the backscattered ultrasound signal and improve image display has stimulated further research. Echocardiographic contrast agents providing left ventricular cavity image enhancement after intravenous injection are now available. A role for contrast echocardiography in the assessment of myocardial perfusion has been established within the invasive clinical setting. With the development of newer contrast agents and new ultrasound technology, myocardial perfusion imaging using contrast echocardiography after venous injection is no longer the unattainable "holy grail," but is fast approaching clinical applicability. Images PMID:8792539

  5. Spherical barium ferrite nanoparticles and hexaferrite single crystals for information data storage and RF devices

    NASA Astrophysics Data System (ADS)

    Jalli, Jeevan Prasad

    Since their discovery in the early 1950's hexagonal ferrites or hexaferrites have been studied for a long time because of their technological applications, such as microwave devices and high density magnetic recording media. In this dissertation efforts have been made to address these two applications by developing nanosized spherical barium ferrite particles for advanced magnetic recording media, and hexaferrite single crystals for low loss RF devices. Accordingly, this dissertation consists of two parts; part one spherical barium ferrite nanoparticles for information data storage media, and part two hexaferrite single crystals for RF devices. Part I. Spherical Barium Ferrite Nanoparticles Hexagonal barium ferrite (H-BaFe) nanoparticles are good candidates for particulate recording media due to their high uniaxial magnetocrystalline anisotropy, excellent chemical stability, and narrow switching field distribution. One major disadvantage of using H-BaFe particles for particulate recording media is their poor dispersion and a high degree of stacking that deteriorate the recording capability by creating large media noise and surface roughness. One way to solve and improve the recording performance of H-BaFe media is employing substantially nanosized spherical barium ferrite (S­BaFe) particles. Spherical shaped particles have low aspect ratio and only form a point-to-point contact, unlike the H-BaFe particles. Therefore, using S-BaFe particles not only decrease the degree of magnetic interaction between the particles but also can substantially increases the recording performance by improving the dispersion and SNR of the particles in the magnetic media. In this dissertation, two different approaches were employed successfully to synthesize S-BaFe nanoparticles in the range of 20-45 nm. Part II. Hexaferrite Single Crystals As wireless communication systems are flourishing, and the operating frequencies are increasing, there is a great demand for RF devices such as

  6. Pedagogical Implications of Contrastive Studies

    ERIC Educational Resources Information Center

    Marton, Waldemar

    1972-01-01

    Pessimism regarding pedagogical applications of contrastive studies, and reasons therefore, are described. Several misunderstandings believed to contribute to this pessimism, and several areas of controversy concerning uses of contrastive studies, are discussed. See FL 508 197 for availability. (RM)

  7. Recognition memory reveals just how CONTRASTIVE contrastive accenting really is

    PubMed Central

    Fraundorf, Scott H.; Watson, Duane G.; Benjamin, Aaron S.

    2010-01-01

    The effects of pitch accenting on memory were investigated in three experiments. Participants listened to short recorded discourses that contained contrast sets with two items (e.g. British scientists and French scientists); a continuation specified one item from the set. Pitch accenting on the critical word in the continuation was manipulated between non-contrastive (H* in the ToBI system) and contrastive (L+H*). On subsequent recognition memory tests, the L+H* accent increased hits to correct statements and correct rejections of the contrast item (Experiments 1–3), but did not impair memory for other parts of the discourse (Experiment 2). L+H* also did not facilitate correct rejections of lures not in the contrast set (Experiment 3), indicating that contrastive accents do not simply strengthen the representation of the target item. These results suggest comprehenders use pitch accenting to encode and update information about multiple elements in a contrast set. PMID:20835405

  8. Site-selective spectroscopy of the solid-state defect chemistry in erbium-doped barium titanate.

    PubMed

    Bak, John D; Wright, John C

    2005-10-01

    Erbium-doped barium titanate crystals were studied by laser-induced fluorescence spectroscopy. Thirteen spectroscopically distinct erbium ion sites were found. The relative concentrations of the different sites changed as a function of the crystal and its preparation and treatment. One major site was present in all crystals. The site distribution was changed either by growing codoped crystals with donor (La3+) and acceptor (Sc3+) ions or by changing the temperature and partial pressure of the oxygen in the annealing atmosphere. Equilibrium calculations were done to simulate the defect distributions that result from the charge compensation of the erbium ions. Comparison with the observed dependence of the site spectral intensities indicated that the erbium enters the lattice on barium sites. We assigned the dominant site to an erbium ion on a barium site that is locally compensated by a barium vacancy, whereas the other lower-intensity sites corresponded to erbium ions that are locally compensated by an electron and a more complex center of an erbium, a barium vacancy, and a hole. The spectra of one sample showed that its defects were different and were characteristic of a sample that had not equilibrated. The new sites in this sample were assigned to erbium entering the lattice on a titanium site, which was then locally compensated by an oxygen vacancy or a hole. Heating equilibrated the sample and changed the erbium to a barium site. PMID:16853368

  9. Phase Contrast Imaging

    SciTech Connect

    Menk, Ralf Hendrik

    2008-11-13

    All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift {phi} directly (using interference phenomena), the gradient {nabla}{sub {phi}}, or the Laplacian {nabla}{sup 2}{phi}. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1

  10. Barium hexaferrite/graphene oxide: controlled synthesis and characterization and investigation of its magnetic properties

    NASA Astrophysics Data System (ADS)

    Maddahfar, Mahnaz; Ramezani, Majid; Mostafa Hosseinpour-Mashkani, S.

    2016-08-01

    In the present study, barium hexaferrite nanocrystals (BaFe12O19) were successfully synthesized through the two-step sol-gel method in an aqueous solution in the presence of barium nitrate and iron (III) nitrate. Besides, the effect of the molar ratio of graphene oxide on the particle size and magnetic properties of final product was investigated. In this research, glucose plays a role as capping and chelating agent in the synthesis of BaFe12O19/graphene oxide. Moreover, it was found that the size, morphology, and magnetic properties of the final products could be greatly influenced by the molar ratio of graphene oxide. BaFe12O19/graphene oxide was characterized by using X-ray diffraction, scanning electron microscope, Fourier transform infrared spectroscopy, vibrating sample magnetometer, and energy-dispersive spectrometry.

  11. Microwave assisted synthesis and characterization of barium titanate nanoparticles for multi layered ceramic capacitor applications.

    PubMed

    Thirumalai, Sundararajan; Shanmugavel, Balasivanandha Prabu

    2011-01-01

    Barium titanate is a common ferroelectric electro-ceramic material having high dielectric constant, with photorefractive effect and piezoelectric properties. In this research work, nano-scale barium titanate powders were synthesized by microwave assisted mechano-chemical route. Suitable precursors were ball milled for 20 hours. TGA studies were performed to study the thermal stability of the powders. The powders were characterized by XRD, SEM and EDX Analysis. Microwave and Conventional heating were performed at 1000 degrees C. The overall heating schedule was reduced by 8 hours in microwave heating thereby reducing the energy and time requirement. The nano-scale, impurity-free and defect-free microstructure was clearly evident from the SEM micrograph and EDX patterns. LCR meter was used to measure the dielectric constant and dielectric loss values at various frequencies. Microwave heated powders showed superior dielectric constant value with low dielectric loss which is highly essential for the fabrication of Multi Layered Ceramic Capacitors. PMID:24427875

  12. Structural, optical and magnetic properties of Fe-doped barium stannate thin films grown by PLD

    NASA Astrophysics Data System (ADS)

    James, K. K.; Aravind, Arun; Jayaraj, M. K.

    2013-10-01

    Barium stannate is a wide band gap semiconductor with cubic perovskite structure. Polycrystalline bulk samples of BaSn1-xFexO3d (BFS), with x = 0.00, 0.02, 0.03, 0.05 and 0.10 were prepared by solid-state reaction. In this paper, we report the growth of undoped and Fe doped barium stannate thin films on fused silica substrate using pulsed laser deposition (PLD) technique at a relatively high substrate temperature and low oxygen pressure. The deposited films have wide bandgap and are transparent in the visible region. The X-ray diffraction analysis of the films confirmed the cubic structure. Microstructural studies were carried out using micro-Raman spectroscopy and AFM analysis. Defect induced Raman shifts were observed in the samples. Magnetic studies revealed an increase in magnetic properties for films doped with 10 at% Fe doped samples.

  13. Single-step synthesis of well-crystallized and pure barium titanate nanoparticles in supercritical fluids

    NASA Astrophysics Data System (ADS)

    Reverón, Helen; Aymonier, Cyril; Loppinet-Serani, Anne; Elissalde, Catherine; Maglione, Mario; Cansell, François

    2005-08-01

    Single-step synthesis of ultra-fine barium titanate powder with a crystallinity as high as 90% and without barium carbonate contamination has been successfully performed under supercritical conditions using a continuous-flow reactor in the temperature range 150-380 °C at 16 MPa. To synthesize this bimetallic oxide, alkoxides, ethanol and water were used. The influence of the synthesis parameters on the BaTiO3 powder characteristics was investigated. The results show that the water to alkoxide precursor ratio, the reactor temperature and the Ba:Ti molar ratio of alkoxide precursor play a major role in the crystallization of pure and well-crystallized BaTiO3 nanoparticles. The continuous mode of operation without post-treatments for powder washing, drying or crystallization increase the industrial interest.

  14. Gamma-ray shielding and structural properties of barium-bismuth-borosilicate glasses

    NASA Astrophysics Data System (ADS)

    Bootjomchai, Cherdsak; Laopaiboon, Jintana; Yenchai, Chadet; Laopaiboon, Raewat

    2012-07-01

    The attenuation coefficients of barium-bismuth-borosilicate glasses have been measured for gamma-ray photon energies of 662, 1173 and 1332 keV using a narrow beam transmission geometry. These coefficients were then used to obtain the values of mass attenuation coefficients, effective atomic number, effective electron density and mean free path. Good agreement has been observed between experimental and theoretical values of these parameters. From the obtained results it is reported here that from the barium-bismuth-borosilicate glasses are better shields to gamma-radiations in comparison to the standard radiation shielding concretes from the shielding point of view. The molar volume, FTIR and acoustic investigations have been used to study the structural properties of the prepared glass system. The obtained results reveal that the formation of non-bridging oxygens occurs at higher concentration of Bi2O3.

  15. Inhibition of barium sulfate deposition by polycarboxylates of various molecular structures

    SciTech Connect

    van der Leeden, M.C.; van Rosmalen, G.M. )

    1990-02-01

    To establish a relationship between the molecular structure of polycarboxylates and their growth-retarding influence on barium sulfate, seeded-suspension-growth experiments were performed at various inhibitor concentrations and pH values. Two types of polycarboxylates with a molecular structure based on their polyacrylic or maleic acid were studied. The molecular structure of these compounds were varied by particle substitution with monomers containing hydroxyl, amide, and sulfonic acid, as well as hydrophobic groups. Hydrophobic groups are detrimental to good inhibitor performance, whereas the introduction of OH, NH {sub 2}, or SO {sub 3} H groups presents opportunities to enhance the inhibitor effectiveness. The sequence in performance of the compounds on barium sulfate was compared with the sequence formerly obtained for calcium sulfate dihydrate.

  16. Mechanisms of laser induced modification of lead and barium vanadate glasses

    SciTech Connect

    Dongol, Ruhil; Tweeton, Landon; Faris, Cory; Feller, Steve; Affatigato, Mario

    2011-01-01

    We report on our investigations on the mechanisms for structural and morphological change in lead and barium vanadate glasses modified by 785 nm laser irradiation. The fundamental process is thermal in nature, leading to phase decomposition, phase changes, and mass transport in the center of the irradiated region, as well as the formation of lead-or barium-rich debris zones. Crystallization is also a consequence of the exposure to the laser light. We further report on preirradiation experiments in which low-power exposure above a determined energy threshold results in structural changes that bridge the gap between the amorphous state and the ultimate crystalline arrangement. Finally, we discuss the application of the laser irradiation in the making of vanadate microspheres.

  17. The electric field structure of auroral arcs as determined from barium plasma injection experiments

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.

    1981-01-01

    Barium plasma injection experiments have revealed a number of features of electric fields in and near auroral forms extending from a few hundred to many thousands of km in altitude. There is evidence for V-type potential structures over some auroras, but not in others. For some auroral arcs, large E fields are found at ionospheric altitudes outside the arc but the E field inside the arc is near zero. In a few other auroras, most recently one investigated in an experiment conducted from Poker Flat on March 22, 1980, large, rapidly fluctuating E fields were detected by barium plasma near 600 km altitude. These E fields suggest that the motion of auroral rays can be an effect of low-altitude electric fields, or that V-type potential structures may be found at low altitudes.

  18. The CAMEO barium release - E/parallel/ fields over the polar cap

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.; Miller, M. L.; Pongratz, M. B.; Smith, G. M.; Smith, L. L.; Mende, S. B.; Nath, N. R.

    1981-01-01

    Four successive thermite barium releases at an altitude of 965 km over polar cap invariant latitudes 84 to 76 deg near magnetic midnight were conducted from the orbiting second stage of the vehicle that launched Nimbus 7; the releases were made as part of the CAMEO (Chemically Active Material Ejected in Orbit) program. This was the first opportunity to observe the behavior of conventional barium release when conducted at orbital velocity in the near-earth magnetic field. The principal unexpected characteristic in the release dynamics was the high, 1.4 to 2.6 km/s, initial Ba(+) expansion velocity relative to an expected velocity of 0.9 km/s. Attention is also given to neutral cloud expansion, initial ion cloud expansion, convective motion, and the characteristics of field-aligned motion. The possibility of measuring parallel electric fields over the polar cap by observing perturbations in the motion of the visible ions is assessed.

  19. Effect of CaF{sub 2} addition on optical properties of barium phosphate glasses

    SciTech Connect

    Kumar, N. Manoj Rao, G. Venkateswara Akhila, B. E. Shashikala, H. D.

    2014-04-24

    Ternary barium phosphate glasses, (50−X)BaO−XCaF{sub 2}−50P{sub 2}O{sub 5} have been prepared by adding 0-10 mol% of CaF{sub 2} to binary barium phosphate glasses. The amorphous nature of the prepared glasses was confirmed by X-ray diffraction technique. The UV-Visible absorption spectra have been recorded, optical band gap energy Eopt and Urbach energy Etail were determined. Shift in Eopt and Etail with increase in concentration of CaF{sub 2} is noted. FTIR analysis was carried out to investigate the short and intermediate-range orders in glasses. Shift of (P-O-P) band to higher wave number with the substitution of BaO with CaF{sub 2} shows the shortening of the phosphate chains. Hardness and density of glass samples were measured and correlated with the composition of glasses.

  20. A critical velocity interaction between fast barium and strontium atoms and the terrestial ionospheric plasma

    NASA Technical Reports Server (NTRS)

    Deehr, C. S.; Wescott, E. M.; Stenbaek-Nielsen, H.; Romick, G. J.; Hallinan, T. J.; Foeppl, H.

    1982-01-01

    A disk of barium and strontium vapor traveling radially outward, perpendicular to the geomagnetic field lines, may be created by the detonation of a high-explosive, radially shaped charge with a liner composed of the two metals in the upper atmosphere. Because of solar radiation resonance, both the barium and the strontium may be optically tracked. Observations indicate the early formation of the metal ions thus evolved into a disk-shaped, stellate structure with a dark hole at the center of a radial structure. The results of these experiments indicate that the process could occur on a cosmic scale, and that unconfirmed aspects of the theory relating to this process could be determined through variation of the parameters in future radial rocket experiments.

  1. Correlated Strontium and Barium Isotopic Compositions of Acid-cleaned Single Mainstream Silicon Carbides from Murchison

    NASA Astrophysics Data System (ADS)

    Liu, Nan; Savina, Michael R.; Gallino, Roberto; Davis, Andrew M.; Bisterzo, Sara; Gyngard, Frank; Käppeler, Franz; Cristallo, Sergio; Dauphas, Nicolas; Pellin, Michael J.; Dillmann, Iris

    2015-04-01

    We present strontium, barium, carbon, and silicon isotopic compositions of 61 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing both strontium and barium contamination. For the first time, by using correlated 88Sr/86Sr and 138Ba/136Ba ratios in mainstream SiC grains, we are able to resolve the effect of 13C concentration from that of 13C-pocket mass on s-process nucleosynthesis, which points toward the existence of large 13C pockets with low 13C concentrations in asymptotic giant branch stars. The presence of such large 13C pockets with a variety of relatively low 13C concentrations seems to require multiple mixing processes in parent asymptotic giant branch stars of mainstream SiC grains.

  2. Oilfield scales: controls on precipitation and crystal morphology of barite (barium sulphate)

    NASA Astrophysics Data System (ADS)

    Stark, A. I. R.; Wogelius, R. A.; Vaughan, D. J.

    2003-04-01

    The precipitation and subsequent build up of barite (barium sulphate) inside extraction tubing presents a costly problem for off shore oil wells which use seawater to mobilize oil during hydrocarbon recovery. Mixing of reservoir formation water containing Ba2+ ions and seawater containing SO_42- ions results in barite precipitation within the reservoir well-bore region and piping. Great effort has been expended in designing strategies to minimize scale formation but details of the reaction mechanism and sensitivity to thermodynamic variables are poorly constrained. Furthermore, few detailed studies have been carried out under simulated field conditions. Hence an experimental programme was designed to study barite formation under environmentally relevant conditions with control of several system variables during the precipitation reaction. Synthetic sea-water and formation-water brines containing sodium sulphate and barium chloride, respectively, were mixed to induce BaSO_4 precipitation. Experiments were carried out at high temperature (100^oC) and high pressure (500 bars) in double rocking autoclave bombs. Barite formation as a function of the addition of calcium, magnesium, and a generic phosphonate based scale inhibitor was investigated whilst maintaining constant pH, temperature and ionic strength (0.5159). Additional experiments were performed at ambient conditions for comparison. Data concerning nucleation, growth rates, and crystal morphology were obtained. ICP-AES data from the supernatant product solutions showed considerable variation in quantity of barium sulphate precipitated as a function of the listed experimental variables. For example, ESEM analysis of barium sulphate crystals showed a dramatic shift in crystal habit from the typical tabular habit produced in control experiments; experiments performed in the presence of foreign cations produced more equant crystals, while those experiments completed in the presence of the phosphonate scale inhibitor

  3. Neodymium-doped barium borate glasses as fluorescent concentrators for the infrared spectral range

    NASA Astrophysics Data System (ADS)

    Dyrba, Marcel; Wiegand, Marie-Christin; Ahrens, Bernd; Schweizer, Stefan

    2012-06-01

    Neodymium-doped barium borate glasses are investigated for their potential as fluorescent concentrators for the near infrared spectral range. Additional doping of the glasses with silver oxide and subsequent heat treatment leads to a reduction of the doped silver ions and to the formation of metallic silver nanoparticles. The formation of the silver nanoparticles is indicated by a broad surface plasmon-related extinction band at approximately 410 nm. The influence of the silver nanoparticles on the fluorescence properties is investigated.

  4. Perforated appendix presenting with severe diarrhea: findings on barium-enema examination

    SciTech Connect

    Picus, D.; Shackelford, G.D.

    1983-10-01

    Severe diarrhea and marked lower abdominal cramps are unusual manifestations of appendicitis. The authors performed a barium-enema examination (BE) on 9 pediatric patients who were utlimately shown to have a perforated appendix and pelvic abscesses. In 8 cases, the atypical symptoms initially led to an incorrect clinical diagnosis. In all 9, the BE demonstrated extensive inflammatory changes of the rectosigmoid colon, caused by the surrounding pelvic infection. Recognizing this clinical and radiographic association could lead to earlier diagnosis and treatment.

  5. The effect of cathode geometry on barium transport in hollow cathode plasmas

    SciTech Connect

    Polk, James E. Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2014-05-14

    The effect of barium transport on the operation of dispenser hollow cathodes was investigated in numerical modeling of a cathode with two different orifice sizes. Despite large differences in cathode emitter temperature, emitted electron current density, internal xenon neutral and plasma densities, and size of the plasma-surface interaction region, the barium transport in the two geometries is qualitatively very similar. Barium is produced in the insert and flows to the surface through the porous structure. A buildup of neutral Ba pressure in the plasma over the emitter surface can suppress the reactions supplying the Ba, restricting the net production rate. Neutral Ba flows into the dense Xe plasma and has a high probability of being ionized at the periphery of this zone. The steady state neutral Ba density distribution is determined by a balance between pressure gradient forces and the drag force associated with collisions between neutral Ba and neutral Xe atoms. A small fraction of the neutral Ba is lost upstream. The majority of the neutral Ba is ionized in the high temperature Xe plasma and is pushed back to the emitter surface by the electric field. The steady state Ba{sup +} ion density distribution results from a balance between electrostatic and pressure forces, neutral Xe drag and Xe{sup +} ion drag with the dominant forces dependent on location in the discharge. These results indicate that hollow cathodes are very effective at recycling Ba within the discharge and therefore maintain a high coverage of Ba on the emitter surface, which reduces the work function and sustains high electron emission current densities at moderate temperatures. Barium recycling is more effective in the cathode with the smaller orifice because the Ba is ionized in the dense Xe plasma concentrated just upstream of the orifice and pushed back into the hollow cathode. Despite a lower emitter temperature, the large orifice cathode has a higher Ba loss rate through the orifice

  6. Preliminary experiments on phase conjugation for flow visualization. [barium titanate single crystals

    NASA Technical Reports Server (NTRS)

    Weimer, D.; Howes, W. L.

    1984-01-01

    Barium titanate single crystals are discussed in the context of: the procedure for polarizing a crystal; a test for phase conjugation; transients in the production of phase conjugation; real time readout by a separate laser of a hologram induced within the crystal, including conjugation response times to on-off switching of each beam; and a demonstration of a Twyman-Green interferometer utilizing phase conjugation.

  7. Effect of chloride incorporation on the crystallization of zirconium-barium-lanthanum-aluminum fluoride glass

    NASA Technical Reports Server (NTRS)

    Neilson, G. F.; Smith, G. L.; Weinberg, M. C.

    1985-01-01

    One aspect of the influence of preparation procedure on the crystallization behavior of a zirconium-barium-lanthanum-aluminum fluoride glass was studied. The crystallization pattern of this glass may be affected by the chlorine concentration within it. In particular, when such glasses are heated at low temperatures, the alpha-Ba-Zr-F6 crystalline phase forms only in those glasses which contain chloride.

  8. The effect of cathode geometry on barium transport in hollow cathode plasmas

    NASA Astrophysics Data System (ADS)

    Polk, James E.; Mikellides, Ioannis G.; Capece, Angela M.; Katz, Ira

    2014-05-01

    The effect of barium transport on the operation of dispenser hollow cathodes was investigated in numerical modeling of a cathode with two different orifice sizes. Despite large differences in cathode emitter temperature, emitted electron current density, internal xenon neutral and plasma densities, and size of the plasma-surface interaction region, the barium transport in the two geometries is qualitatively very similar. Barium is produced in the insert and flows to the surface through the porous structure. A buildup of neutral Ba pressure in the plasma over the emitter surface can suppress the reactions supplying the Ba, restricting the net production rate. Neutral Ba flows into the dense Xe plasma and has a high probability of being ionized at the periphery of this zone. The steady state neutral Ba density distribution is determined by a balance between pressure gradient forces and the drag force associated with collisions between neutral Ba and neutral Xe atoms. A small fraction of the neutral Ba is lost upstream. The majority of the neutral Ba is ionized in the high temperature Xe plasma and is pushed back to the emitter surface by the electric field. The steady state Ba+ ion density distribution results from a balance between electrostatic and pressure forces, neutral Xe drag and Xe+ ion drag with the dominant forces dependent on location in the discharge. These results indicate that hollow cathodes are very effective at recycling Ba within the discharge and therefore maintain a high coverage of Ba on the emitter surface, which reduces the work function and sustains high electron emission current densities at moderate temperatures. Barium recycling is more effective in the cathode with the smaller orifice because the Ba is ionized in the dense Xe plasma concentrated just upstream of the orifice and pushed back into the hollow cathode. Despite a lower emitter temperature, the large orifice cathode has a higher Ba loss rate through the orifice because the Xe

  9. Establishment of a Protocol for Determining Gastrointestinal Transit Time in Mice Using Barium and Radiopaque Markers

    PubMed Central

    Myagmarjalbuu, Bolormaa; Moon, Myeong Ju; Heo, Suk Hee; Jeong, Seo In; Park, Jong-Seong; Jun, Jae Yeoul; Kang, Heoung Keun

    2013-01-01

    Objective The purpose of this study was to establish a minimally invasive and reproducible protocol for estimating the gastrointestinal (GI) transit time in mice using barium and radiopaque markers. Materials and Methods Twenty 5- to 6-week-old Balb/C female mice weighing 19-21 g were used. The animals were divided into three groups: two groups that received loperamide and a control group. The control group (n = 10) animals were administered physiological saline (1.5 mL/kg) orally. The loperamide group I (n = 10) and group II (n = 10) animals were administered 5 mg/kg and 10 mg/kg loperamide orally, respectively. Thirty minutes after receiving the saline or loperamide, the mice was administered 80 µL of barium solution and six iron balls (0.5 mm) via the mouth and the upper esophagus by gavage, respectively. Afterwards, the mice were continuously monitored with fluoroscopic imaging in order to evaluate the swallowing of the barium solution and markers. Serial fluoroscopic images were obtained at 5- or 10-min intervals until all markers had been excreted from the anal canal. For analysis, the GI transit times were subdivided into intestinal transit times (ITTs) and colon transit times (CTTs). Results The mean ITT was significantly longer in the loperamide groups than in the control group (p < 0.05). The mean ITT in loperamide group II (174.5 ± 32.3) was significantly longer than in loperamide group I (133.2 ± 24.2 minute) (p < 0.05). The mean CTT was significantly longer in loperamide group II than in the control group (p < 0.05). Also, no animal succumbed to death after the experimental procedure. Conclusion The protocol for our study using radiopaque markers and barium is reproducible and minimally invasive in determining the GI transit time of the mouse model. PMID:23323030

  10. Perceived contrast in complex images

    PubMed Central

    Haun, Andrew M.; Peli, Eli

    2013-01-01

    To understand how different spatial frequencies contribute to the overall perceived contrast of complex, broadband photographic images, we adapted the classification image paradigm. Using natural images as stimuli, we randomly varied relative contrast amplitude at different spatial frequencies and had human subjects determine which images had higher contrast. Then, we determined how the random variations corresponded with the human judgments. We found that the overall contrast of an image is disproportionately determined by how much contrast is between 1 and 6 c/°, around the peak of the contrast sensitivity function (CSF). We then employed the basic components of contrast psychophysics modeling to show that the CSF alone is not enough to account for our results and that an increase in gain control strength toward low spatial frequencies is necessary. One important consequence of this is that contrast constancy, the apparent independence of suprathreshold perceived contrast and spatial frequency, will not hold during viewing of natural images. We also found that images with darker low-luminance regions tended to be judged as having higher overall contrast, which we interpret as the consequence of darker local backgrounds resulting in higher band-limited contrast response in the visual system. PMID:24190908

  11. Optical planar waveguide in sodium-doped calcium barium niobate crystals by carbon ion implantation

    NASA Astrophysics Data System (ADS)

    Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Fu, Gang; Wang, Hui-Lin; Wang, Xue-Lin

    2013-07-01

    There is great interest in niobate crystals which belong to the tetragonal tungsten bronze (TTB) families owing to their intriguing properties. As one representative of such crystals, CBN (calcium barium niobate) has attracted rapidly growing attention. Because it has a higher Curie temperature than SBN (strontium barium niobate), possesses outstanding ferroelectric and it possesses optical properties. In addition, doped with sodium, CBN will show a higher Curie temperature than pure CBN. We report on the fabrication and characterization of optical planar waveguide in x-cut sodium-doped calcium barium niobate crystal by using C ion implantation. The guided-mode properties at the wavelength of 633 and 1539 nm are investigated through prism-coupling measurements, respectively. By applying direct end-face coupling arrangement, the near-field optical intensity distribution of waveguide modes is measured at 633 nm. For comparison, the modal profile of the same guided mode is also numerically calculated by the finite difference beam-propagation method via computer software BeamPROP. The transmission spectra of the waveguide before and after ion implantation treatments were investigated also. Our experiment results reveal that the waveguide could propagate light with transverse magnetic polarized direction only and it is assumed that the polarization selectivity of CBN crystal may responsible for this phenomenon.

  12. Precipitation of Calcium, Magnesium, Strontium and Barium in Tissues of Four Acacia Species (Leguminosae: Mimosoideae)

    PubMed Central

    He, Honghua; Bleby, Timothy M.; Veneklaas, Erik J.; Lambers, Hans; Kuo, John

    2012-01-01

    Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory. PMID:22848528

  13. Quantitative measurements of vaporization, burst ionization, and emission characteristics of shaped charge barium releases

    SciTech Connect

    Hoch, E.L.; Hallinan, T.J.; Stenbaek-Nielsen, H.C.

    1994-07-01

    Intensity-calibrated color video recordings of three barium-shaped charge injections in the ionosphere were used to determine the initial ionization, the column density corresponding to unity optical depth, and the yield of vaporized barium in the fast jet. It was found that the initial ionization at the burst was less than 1% and that 0% burst ionization was consistent with the observations. Owing to the Doppler shift, the column density for optical thickness in the neutral barium varies somewhat according to the velocity distribution. For the cases examined here, the column density was 2-5x10{sup 10} atoms/cm{sup 2}. This value, which occurred 12 to 15 s after release, should be approximately valid for most shaped charge experiments. The yield was near 30% (15% in the fast jet) for two of the releases and was somewhat lower in the third, which also had a lower peak velocity. This study also demonstrated the applicability of the computer simulation code developed for chemical releases by Stenbaek-Nielsen and provided experimental verification of the Doppler-corrected emission rates calculated by Stenbaek-Nielsen (1989). 22 refs., 4 figs., 6 tabs.

  14. Computer modelling of the reduction of rare earth dopants in barium aluminate

    SciTech Connect

    Rezende, Marcos V. dos S; Valerio, Mario E.G.; Jackson, Robert A.

    2011-08-15

    Long lasting phosphorescence in barium aluminates can be achieved by doping with rare earth ions in divalent charge states. The rare earth ions are initially in a trivalent charge state, but are reduced to a divalent charge state before being doped into the material. In this paper, the reduction of trivalent rare earth ions in the BaAl{sub 2}O{sub 4} lattice is studied by computer simulation, with the energetics of the whole reduction and doping process being modelled by two methods, one based on single ion doping and one which allows dopant concentrations to be taken into account. A range of different reduction schemes are considered and the most energetically favourable schemes identified. - Graphical abstract: The doping and subsequent reduction of a rare earth ion into the barium aluminate lattice. Highlights: > The doping of barium aluminate with rare earth ions reduced in a range of atmospheres has been modelled. > The overall solution energy for the doping process for each ion in each reducing atmosphere is calculated using two methods. > The lowest energy reduction process is predicted and compared with experimental results.

  15. Barium Surface Abundances of Blue Stragglers in the Open Cluster NGC 6819

    NASA Astrophysics Data System (ADS)

    Milliman, Katelyn E.; Mathieu, Robert D.; Schuler, Simon C.

    2015-09-01

    We present a barium surface abundance of 12 blue stragglers (BSs) and 18 main-sequence (MS) stars in the intermediate-age open cluster NGC 6819 (2.5 Gyr) based on spectra obtained from the Hydra Multi-object Spectrograph on the WIYN 3.5 m telescope. For the MS stars we find [Fe/H] = +0.05 ± 0.04 and [Ba/Fe] = -0.01 ± 0.10. The majority of the BS stars are consistent with these values. We identify five BSs with significant barium enhancement. These stars most likely formed through mass transfer from an asymptotic giant branch star that polluted the surface of the BS with the nucleosynthesis products generated during thermal pulsations. This conclusion aligns with the results from the substantial work done on the BSs in old open cluster NGC 188 that identifies mass transfer as the dominant mechanism for BS formation in that open cluster. However, four of the BSs with enhanced barium show no radial-velocity evidence for a companion. The one star that is in a binary is a double-lined system, meaning the companion is not a white dwarf and not the remnant of a prior AGB star. In this paper we attempt to develop a consistent scenario to explain the origin of these five BSs.

  16. Accidental embryo irradiation during barium enema examinations: An estimation of absorbed dose

    SciTech Connect

    Damilakis, J.; Perisinakis, K.; Grammatikakis, J.

    1996-04-01

    The purpose of this report is to investigate the possibility of an embryo to receive a dose of more than 10 cGy, the threshold of malformation induction in embryos reported by the International Commission on Radiological Protection, during barium enema examinations. Thermoluminescent dosimeters were place in a phantom to calculate the depth-to-skin conversion coefficient needed for dose estimation at the average embryo depth in patients. Barium enema examinations were performed in 20 women of childbearing age with diagnostic problems demanding longer fluoroscopy times. Doses at 6 cm, the average embryo depth, were determined by measurements at the patients` skin followed by dose calculation at the site of interest. The range of doses estimated at embryo depth for patients was 1.9 to 8.2 cGy. The dose always exceeded 5 cGy when fluoroscopy time was longer than 7 minutes. The dose at the embryo depth never exceeded 10 cGy. This study indicates that fluoroscopy time should not exceed 7 minutes in childbearing-age female patients undergoing barium enema examinations. 6 refs., 1 fig., 2 tabs.

  17. An assessment of the redistribution of Barium during diagenesis of Marcellus Shale

    NASA Astrophysics Data System (ADS)

    Renock, D.; Symcox, C.; Lanids, J. D.; Sharma, M.

    2012-12-01

    Produced water from the hydrofracturing of Marcellus Shale have been reported to contain barium at concentrations >4000 ppm (Gregory et al, 2011). Understanding the reactions responsible for the leaching of Ba into produced water is important for improving the economic viability of gas extraction and to mitigate environmental concerns. Core samples of Marcellus Shale from New York and Pennsylvania were shown to contain Ba in the range of 400-2200 μg/g. In some of these samples, barite (BaSO4) grains are shown to be partially replaced by pyrite (massive and framboidal varieties) suggesting that Ba is remobilized in the zone of sulfate reduction sometime after sedimentation. Sequential extraction experiments show Ba being released into buffered acetic acid (carbonate fraction), aqua regia (sulfide fraction), and hydrofluoric acid (silicate fraction) extractions despite ~50% of the barium remaining undissolved as barite. Laser ablation ICP-MS showed negligible concentrations of Ba in calcite veins and elevated concentrations in areas of the shale that are predominantly clay + organics. These results suggest that some of the Ba is associated with the clay fraction of the shale (e.g., sorbed to clay surfaces as a result of the anoxic dissolution of barite). These results may inform future strategies for mitigating the release of barium into produced water.

  18. Barium cloud evolution and striation formation in the magnetospheric release on September 21, 1971

    NASA Technical Reports Server (NTRS)

    Adamson, D.; Fricke, C. L.

    1974-01-01

    The joint NASA-Max Planck Institute Barium Ion Cloud (BIC) Experiment on September 21, 1971 involved the release of 1.7 kg of neutral barium at an altitude of 31,500 km at a latitude of 6.93 deg N. and a longitude of 74.40 deg W. A theoretical model describing the barium neutral cloud expansion and the ion cloud formation is developed. The mechanism of formation of the striational features observed in the release is also discussed. Two candidate instabilities, which may contribute to striation formation, are examined. The drift instability stemming from the outwardly directed drag force exerted on the ions by the outstreaming neutrals is rejected on the grounds that the ion density is too low during the collision-dominated phase of the cloud expansion to support this kind of instability. The joint action of Rayleigh-Taylor and flute instabilities plausibly accounts for the observed striational structure. This same mechanism may well be operative at times of sudden injection of plasma into the inner magnetosphere during geomagnetic storms and may thus contribute to the formation of field-alined inhomogeneities which serve as whistler ducts.

  19. Yield and ion distribution for the barium cloud at 31,000 kilometers, September 21, 1971.

    NASA Technical Reports Server (NTRS)

    Manring, E. R.; Patty, R. R.

    1973-01-01

    The photon flux density associated with the 4554-A resonance radiation for Ba II was measured at Mount Hopkins, Arizona, and Cerro Morado, Chile, and was determined to be 36,000 photon/sq cm sec outside the atmosphere; this measurement was made when the cloud was optically thin at 120 sec after release. Using this and a photon scattering efficiency of 0.66 photon/ion sec we estimate a 1.7-kg yield of barium ions that are formed from the initially released atomic barium and are thus associated with the main core of the cloud. Photographic and photometric data are combined to obtain preliminary values for the brightness throughout the cloud for two photographs, and isobrightness plots are presented. These plots indicate that the cloud is quite narrow, that a considerable portion of the ionized barium is outside the main core after a few minutes, and that the striations contain only a small fraction of the total material.

  20. Quantitative measurements of vaporization, burst ionization, and emission characteristics of shaped charge barium releases

    NASA Technical Reports Server (NTRS)

    Hoch, Edward L.; Hallinan, Thomas J.; Stenbaek-Nielsen, Hans C.

    1994-01-01

    Intensity-calibrated color video recordings of three barium-shaped charge injections in the ionopshere were used to determine the initial ionization, the column density corresponding to unity optical depth, and the yield of vaporized barium in the fast jet. It was found that the initial ionization at the burst was less than 1% and that 0% burst ionization was consistent with the observations. Owing to the Doppler shift, the column density for optical thickness in the neutral barium varies somewhat according to the velocity distribution. For the cases examined here, the column density was 2-5 x 10(exp 10) atoms/sq cm. This value, which occurred 12 to 15 s after release, should be approximately valid for most shaped charge experiments. The yield was near 30% (15% in the fast jet) for two of the releases and was somewhat lower in the third, which also had a lower peak velocity. This study also demonstrated the applicability of the computer simulation code developed for chemical releases by Stenbaek-Nielsen and provided experimental verification of the Doppler-corrected emission rates calculated b Stenbaek-Nielsen (1989).

  1. ARE THERE ANY STARS LACKING NEUTRON-CAPTURE ELEMENTS? EVIDENCE FROM STRONTIUM AND BARIUM

    SciTech Connect

    Roederer, Ian U.

    2013-01-01

    The cosmic dispersion in the abundances of the heavy elements strontium and barium in halo stars is well known. Strontium and barium are detected in most cool, metal-poor giants, but are these elements always detectable? To identify stars that could be considered probable candidates for lacking these elements, I examine the stellar abundance data available in the literature for 1148 field stars and 226 stars in dwarf galaxies, 776 of which have metallicities lower than [Fe/H] <-2.0. Strontium or barium have been detected in all field, globular cluster, and dwarf galaxy environments studied. All upper limits are consistent with the lowest detected ratios of [Sr/H] and [Ba/H]. The frequent appearance of these elements raises the intriguing prospect that at least one kind of neutron-capture reaction operates as often as the nucleosynthesis mechanisms that produce lighter elements, such as magnesium, calcium, or iron, although the yields of heavy elements may be more variable.

  2. Estimation of barium evaporation rate from emission measurement of dispenser cathodes

    NASA Astrophysics Data System (ADS)

    Ravi, M.; Bhat, K. S.

    2003-06-01

    Dispenser cathodes of type M (Os-Ru coated) have been fabricated in the laboratory and tested for their emission characteristics in a sealed glass bulb in a closely spaced diode configuration. It is observed that the pulsed emission current in the temperature limited region decreased with time during the first few hours of operation and later stabilized at a constant value. This initial fall of emission current is attributed to the back bombardment of barium atoms from the anode resulting in an increase in the effective work function of the cathode surface. The decrease in emission current with time was found to follow a t1/2 relation. It was also observed that when the anode was baked at about 800 °C B for a few minutes the original emission current was restored, thus suggesting that the barium evaporated on the anode was responsible for such a behavior. A theoretical model has been suggested for estimation of barium evaporation rate from the above time dependent emission phenomenon observed.

  3. Epitaxy barium ferrite thin films on LiTaO3 substrate

    NASA Astrophysics Data System (ADS)

    Fang, H. C.; Ong, C. K.; Xu, S. Y.; Tan, K. L.; Lim, S. L.; Li, Y.; Liu, J. M.

    1999-08-01

    Barium hexaferrite (BaM) thin films were deposited on (0001) LiTaO3 substrates by pulsed laser deposition. Effects of the substrate temperature and oxygen gas pressure on the formation and quality of these films were studied. Films deposited at a substrate temperature of 800 °C and an oxygen pressure around 0.23 mbar showed the best c axis normal to the film plane with locked in-plane orientation. The saturation magnetization Ms and anisotropy field Ha measured by vibrating sample magnetometer were almost the same as those reported on bulk barium ferrite. Decreasing oxygen pressure hinders the formation of the Ba layer in BaM magnetoplumbite structure and gives rise to the spinel phase, which greatly decreases coercivity Hc of the films and finally destroys the whole BaM structure. Effects of the lattice mismatch and substrate-induced strains on the film structure were also studied. It was found that barium ferrite thin films grown on LiTaO3 substrates tend to choose a matching mode with compressional strains rather than shear strains.

  4. Non-toxic lead sulfide nanodots as efficient contrast agents for visualizing gastrointestinal tract.

    PubMed

    Liu, Zhen; Ran, Xiang; Liu, Jianhua; Du, Yingda; Ren, Jinsong; Qu, Xiaogang

    2016-09-01

    Non-invasive imaging of gastrointestinal (GI) tract using novel but efficient contrast agents is of the most important issues in the diagnosis and prognosis of GI diseases. Here, for the first time, we reported the design and synthesis of biothiol-decorated lead sulfide nanodots, as well as their usages in functional dual-modality imaging of GI tract in vivo. Due to the presence of glutathione on the surface of the nanodots, these well-prepared contrast agents could decrease the unwanted ion leakage, withstand the harsh conditions in GI tract, and avoid the systemic absorption after oral administration. Compared with clinical barium meal and iodine-based contrast agents, these nanodots exhibited much more significant enhancement in contrast efficiency during both 2D X-ray imaging and 3D CT imaging. Different from some conventional invasive imaging modalities, such as gastroscope and enteroscope, non-invasive imaging strategy by using glutathione modified PbS nanodots as contrast agents could reduce the painfulness towards patients, facilitate the imaging procedure, and economize the manipulation period. Moreover, long-term toxicity and bio-distribution of these nanodots after oral administration were evaluated in detail, which indicated their overall safety. Based on our present study, these nanodots could act as admirable contrast agents to integrate X-ray imaging and CT imaging for the direct visualization of GI tract. PMID:27240159

  5. Electric fields and plasma waves resulting from a barium injection experiment

    SciTech Connect

    Koons, H.C.; Pongratz, M.B.

    1981-03-01

    A shaped-charge, barium plasma injection experiment was performed in June 1976 from the DOE Kauai test facility. The rocket payload contained seven shaped charges, a sevenfold larger package than the typical payloads employed in previous barium plasma injections conducted in this program. An attitude control system oriented the injection perpendicular to the local geomagnetic field. The injection altitude was 450 km. The second-stage motor section contained a payload to measure dc and ac electric fields using a 5-m-long, tip-to-tip dual spherical probe antenna. The ac electric field frequency response was from 100 Hz to 12 kHz. The dc channel responds up to 160 Hz. Shortly after the detonation, the dc electric field was parallel to the geomagnetic field. A few seconds later the measured electric field was the v x B field induced by the motion of the antenna through the plasma. A variety of plasma waves were detected for approximately 20 s following the injection. The initial impulse in the dc channel was measured to be 115 mV/m. The injection generated barium cyclotron waves at 3.4, 7.2, and 10.6 Hz. The barium gyrofrequency at the altitude of the injection was 3.3 Hz. The initial amplitude at 3.4 Hz was 25 mV/m peak-to-peak. These waves were evident in the data for approximately 6 s. Between 3 and 8 after the explosion, band-limited noise was intermittently present between 1.6 and 3.2 kHz. These emissions were lower-hybrid-resonance emissions in a barium plasma. The instability responsible for these emissions is tentatively identified as the modified two-stream instability. Wide-band noise with a decreasing intensity as a function of frequency in the band from 100 Hz to 5 kHz was present from 4 to 30 s following the explosion. The intensity maximized when the antenna was most nearly parallel to the geomagnetic field. This suggests that the waves were ion acoustic waves. Highly structured emission occurred between 500 Hz for several seconds after the explosion.

  6. [Using barium fluoride fine particles as stationary phase for TLC/FTIR analysis].

    PubMed

    Liu, Xi; Pan, Qing-hua; Ding, Jie; Zhu, Qing; He, An-qi; Yue, Shi-juan; Li, Xiao-pei; Hu, Li-ping; Xia, Jin-ming; Liu, Cui-ge; Wei, Yong-ju; Yu, Jiang; Yang, Zhan-lan; Zhu, Xi; Xu, Yi-zhuang; Wu, Jin-guang

    2011-07-01

    In situ TLC/FTIR technique has tremendous potential in the analysis of complex mixtures. However, the progress in this technique was quite slow. The reason is that conventional stationary phase such as silica gel etc. has strong absorption in FTIR spectrum and thus brings about severe interference in the detection of samples. To solve the problem, the authors propose to use barium fluoride fine particles as stationary phase of TLC plate. The reasons are as follows: Barium fluoride wafer has been extensively used as infrared window in FTIR experiments and it has no absorbance in an IR region between 4 000 and 800 cm'. As a matter of fact, the atomic mass of barium and fluoride is quite large, thus the normal vibration of BaF2 lattice is limited in far-IR region and low frequency part of mid-IR region. Therefore, the interference caused by IR absorption of stationary phase can be resolved if BaF2 is used as stationary phase of TLC plate. Moreover, BaF2 is quite stable and insolvable in water and most organic solvents and it will not be dissolved by mobile phase or react with samples in TLC separation. Additionally, decreasing the particle size of BaF2 is very important in TLC/FTIR analysis technique. The reason is two-fold: First, decreasing the particle size of stationary phase is helpful to improving the efficiency of separation by TLC plate; second, decreasing the size of BaFz particle can improve the quality of FTIR spectra by alleviating the problem of light scattering. By optimizing the synthetic conditions, fine particles of barium fluoride were obtained. SEM results indicate that the size of the BaF2 particles is around 500 nm. FTIR spectrum of the BaF2 particles shows that no absorption of impurity was observed. Moreover, the elevation of baseline caused by light scattering is insignificant. The authors have developed a new technique named "settlement volatilization method" to prepare TLC plate without polymeric adhesive that may bring about significant

  7. Mobility and fluorescence of barium ions in xenon gas for the exo experiment

    NASA Astrophysics Data System (ADS)

    Benitez Medina, Julio Cesar

    The Enriched Xenon Observatory (EXO) is an experiment which aims to observe the neutrinoless double beta decay of 136Xe. The measurement of this decay would give information about the absolute neutrino mass and whether or not the neutrino is its own antiparticle. Since this is a very rare decay, the ability to reject background events by detecting the barium ion daughter from the double beta decay would be a major advantage. EXO is currently operating a detector with 200 kg of enriched liquid xenon, and there are plans to build a ton scale xenon detector. Measurements of the purity of liquid xenon in our liquid xenon test cell are reported. These results are relevant to the research on detection of single barium ions by our research group at Colorado State University. Details of the operation of the purity monitor are described. The effects of using a purifier, recirculation and laser ablation on the purity of liquid xenon are discussed. Mobility measurements of barium in xenon gas are reported for the first time. The variation of mobility with xenon gas pressure suggests that a significant fraction of molecular ions are formed when barium ions interact with xenon gas at high pressures. The measured mobility of Ba+ in Xe gas at different pressures is compared with the predicted theoretical value, and deviations are explained by a model that describes the fraction of molecular ions in Xe gas as a function of pressure. The results are useful for the analysis of experiments of fluorescence of Ba+ in xenon gas. It is also important to know the mobility of the ions in order to calculate the time they interact with an excitation laser in fluorescence experiments and in proposed 136 Ba+ daughter detection schemes. This thesis presents results of detection of laser induced fluorescence of Ba+ ions in Xe gas. Measurements of the pressure broadening of the excitation spectra of Ba+ in xenon gas are presented. Nonradiative decays due to gas collisions and optical pumping

  8. Barium in hemipelagic sediment of the northwest Pacific: Coupling with biogenic carbonate

    NASA Astrophysics Data System (ADS)

    Hyun, Sangmin; Han, Sang-Joon; Taira, Asahiko

    2002-11-01

    Geochemical analyses were performed on three cores of hemipelagic sediment from the northwest Pacific Ocean (eastern edge of Shikoku Basin) dating from the last interglacial and glacial periods. The objective of this work is to delineate the relations between excess sedimentary barium [Ba(ex)] content and biogenic opal, carbonate, and organic carbon contents. Calculated Ba(ex) values show variable degrees of correlation with biogenic sediment fractions. The mass accumulation rate (MAR) of Ba(ex) covaries with the MARs of biogenic fractions, and in particular, with the MAR of biogenic carbonate (r2 = 0.68) and TOC (R2 = 0.50). Variable relations between barium and biogenic fractions in hemipelagic sediment provide detailed insight into the behavior of sedimentary barium. It appears that a significant proportion of the barium is affiliated with the carbonate fractions. Based on this strong correlation, carbonate dissolution rates of the last glacial to interglacial periods are estimated. Assuming that the MARs of carbonate and Ba(ex) covary, variation of the Ba/Ca ratio in sediments reflects the extent of postdepositional carbonate dissolution. The record of sedimentary Ba/Ca ratios exhibits striking difference between sediment of the glacial and interglacial periods, with a higher positive correlation during glacial intervals and a lower correlation during interglacial intervals; this pattern is the result of enhanced carbonate dissolution during interglacial times. Sedimentary Ba/Ca ratios may, therefore, be a useful tool for estimating the relative extent of carbonate dissolution. Ba(ex) curves and patterns in sedimentary Ba/Ca ratios resemble the established Pacific carbonate dissolution record (i.e., enhanced dissolution during interglacial times and reduced dissolution during glacial times) as suggested by previous studies. Variations in sedimentary Ba/Ca ratios strongly support an interpretation of pronounced glacial-interglacial fluctuation in carbonate

  9. Potential of high-Z contrast agents in clinical contrast-enhanced computed tomography

    SciTech Connect

    Nowak, Tristan; Hupfer, Martin; Brauweiler, Robert; Eisa, Fabian; Kalender, Willi A.

    2011-12-15

    Purpose: Currently, only iodine- and barium-based contrast media (CM) are used in clinical contrast-enhanced computed tomography (CE-CT). High-Z metals would produce a higher contrast at equal mass density for the x-ray spectra used in clinical CT. Using such materials might allow for significant dose reductions in CE-CT. The purpose of this study was to quantify the potential for dose reduction when using CM based on heavy metals. Methods: The contrast-to-noise ratio weighted by dose (CNRD) was determined as a function of scan protocol by means of measurements and simulations on a clinical CT scanner. For simulations, water cylinders with diameters 160, 320, 480, and 640 mm were used to cover a broad range of patient sizes. Measurements were conducted with 160 and 320 mm water-equivalent plastic cylinders. A central bore of 13 mm diameter was present in all phantoms. The tube voltage was varied from 80 to 140 kV for measurements and from 60 to 180 kV for simulations. Additional tin filtration of thicknesses 0.4, 0.8, and 1.2 mm was applied in the simulation to evaluate a range of spectral hardness. The bore was filled with a mixture of water and 10 mg/ml of pure iodine, holmium, gadolinium, ytterbium, osmium, tungsten, gold, and bismuth for the simulations and with aqueous solutions of ytterbium, tungsten, gold, and bismuth salts as well as Iopromid containing 10 mg/ml of the pure materials for the measurements. CNRDs were compared to iodine at phantom size-dependent reference voltages for all high-Z materials and the resulting dose reduction was calculated for equal contrast-to-noise ratio. Results: Dose reduction potentials strongly depended on phantom size, spectral hardness, and tube voltage. Depending on the added filtration, a dose reduction of 19%-60% could be reached at 80 kV with gadolinium for the 160 mm phantom, 52%-69% at 100 kV with holmium for the 320 mm phantom, 62%-78% with 120 kV for hafnium and the 480 mm phantom and 74%-86% with 140 kV for gold

  10. Dielectric relaxation of barium strontium titanate and application to thin films for DRAM capacitors

    NASA Astrophysics Data System (ADS)

    Baniecki, John David

    This thesis examines the issues associated with incorporating the high dielectric constant material Barium Strontium Titanate (BSTO) in to the storage capacitor of a dynamic random access memory (DRAM). The research is focused on two areas: characterizing and understanding the factors that control charge retention in BSTO thin films and modifying the electrical properties using ion implantation. The dielectric relaxation of BSTO thin films deposited by metal-organic chemical vapor deposition (MOCVD) is investigated in the time and frequency domains. It is shown that the frequency dispersion of the complex capacitance of BSTO thin films can be understood in terms of a power-law frequency dependence from 1mHz to 20GHz. From the correspondence between the time and frequency domain measurements, it is concluded that the power-law relaxation currents extend back to the nano second regime of DRAM operation. The temperature, field, and annealing dependence of the dielectric relaxation currents are also investigated and mechanisms for the observed power law relaxation are explored. An equivalent circuit model of a high dielectric constant thin film capacitor is developed based on the electrical measurements and implemented in PSPICE. Excellent agreement is found between the experimental and simulated electrical characteristics showing the utility of the equivalent circuit model in simulating the electrical properties of high dielectric constant thin films. Using the equivalent circuit model, it is shown that the greatest charge loss due to dielectric relaxation occurs during the first read after a refresh time following a write to the opposite logic state for a capacitor that has been written to the same logic state for a long time (opposite state write charge loss). A theoretical closed form expression that is a function of three material parameters is developed which estimates the opposite state write charge loss due to dielectric relaxation. Using the closed form

  11. Air resources

    SciTech Connect

    1995-10-01

    This section describes the ambient (surrounding) air quality of the TVA region, discusses TVA emission contributions to ambient air quality, and identifies air quality impacts to human health and welfare. Volume 2 Technical Document 2, Environmental Consequences, describes how changes in TVA emissions could affect regional air quality, human health, environmental resources, and materials. The primary region of the affected environment is broadly defined as the state of Tennessee, as well as southern Kentucky, western Virginia, southern West Virginia, western North Carolina, and northern Georgia, Alabama, and Mississippi. This area represents the watershed of the Tennessee River and the 201 counties of the greater TVA service area. Emissions from outside the Tennessee Valley region contribute to air quality in the Valley. Also, TVA emissions are transported outside the Valley and have some impact on air quality beyond the primary study area. Although the study area experiences a number of air quality problems, overall air quality is good.

  12. Pattern specificity of contrast adaptation

    PubMed Central

    Anstis, Stuart

    2014-01-01

    Contrast adaptation is specific to precisely localised edges, so that adapting to a flickering photograph makes one less sensitive to that same photograph, but not to similar photographs. When two low-contrast photos, A and B, are transparently superimposed, then adapting to a flickering high-contrast B leaves no net afterimage, but it makes B disappear from the A+B picture, which now simply looks like A. PMID:25165518

  13. Nuclear magnetic resonance contrast agents

    DOEpatents

    Smith, Paul H.; Brainard, James R.; Jarvinen, Gordon D.; Ryan, Robert R.

    1997-01-01

    A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC.sub.16 H.sub.14 N.sub.6. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques.

  14. Nuclear magnetic resonance contrast agents

    DOEpatents

    Smith, P.H.; Brainard, J.R.; Jarvinen, G.D.; Ryan, R.R.

    1997-12-30

    A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC{sub 16}H{sub 14}N{sub 6}. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques. 10 figs.

  15. Air Pollution.

    ERIC Educational Resources Information Center

    Gilpin, Alan

    A summary of one of our most pressing environmental problems, air pollution, is offered in this book by the Director of Air Pollution Control for the Queensland (Australia) State Government. Discussion of the subject is not restricted to Queensland or Australian problems and policies, however, but includes analysis of air pollution the world over.…

  16. Magnetic field induced differential neutron phase contrast imaging

    SciTech Connect

    Strobl, M.; Treimer, W.; Walter, P.; Keil, S.; Manke, I.

    2007-12-17

    Besides the attenuation of a neutron beam penetrating an object, induced phase changes have been utilized to provide contrast in neutron and x-ray imaging. In analogy to differential phase contrast imaging of bulk samples, the refraction of neutrons by magnetic fields yields image contrast. Here, it will be reported how double crystal setups can provide quantitative tomographic images of magnetic fields. The use of magnetic air prisms adequate to split the neutron spin states enables a distinction of field induced phase shifts and these introduced by interaction with matter.

  17. STRONTIUM AND BARIUM IN EARLY-TYPE GALAXIES

    SciTech Connect

    Conroy, Charlie; Van Dokkum, Pieter G.; Graves, Genevieve J.

    2013-02-01

    The detailed abundance patterns of the stars within galaxies provide a unique window into the history of star formation (SF) at early times. Two widely used 'chronometers' include the {alpha} and iron-peak elements, which are created on short and long timescales, respectively. These two clocks have been widely used to estimate SF timescales from moderate-resolution spectra of early-type galaxies. Elements formed via s-process neutron captures (e.g., Sr and Ba) comprise a third type of chronometer, as the site of the main s-process is believed to be intermediate and low-mass asymptotic giant branch stars. The [{alpha}/Ba] ratio in particular should provide a powerful new constraint on the SF histories of galaxies, in part because it is insensitive to the uncertain distribution of Type Ia supernovae detonation times and the overall Ia rate. Here we present new measurements of the abundance of Sr and Ba in nearby early-type galaxies by applying stellar population synthesis tools to high signal-to-noise optical spectra. We find a strong anti-correlation between [Mg/Fe] and [Ba/Fe], and a strong positive correlation between [Mg/Ba] and galaxy velocity dispersion. These trends are consistent with the idea that more massive galaxies formed their stars on shorter timescales compared to less massive galaxies, and rule out several other proposed explanations for the observed super-solar [Mg/Fe] values in massive galaxies. In contrast, [Sr/Fe] {approx}0, with no strong variation across the sample. It is difficult to interpret the Sr trends without detailed chemical evolution models owing to the multiplicity of proposed nucleosynthetic sites for Sr.

  18. ZIRCONIUM, BARIUM, LANTHANUM, AND EUROPIUM ABUNDANCES IN OPEN CLUSTERS

    SciTech Connect

    Jacobson, Heather R.; Friel, Eileen D. E-mail: efriel@indiana.edu

    2013-04-15

    We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight increase with increasing cluster age, although with marginal statistical significance. Ratios of [s/r]-process abundances, [Ba/Eu] and [La/Eu], however, show more clearly the increasing efficiency of s-process relative to r-process enrichment in open cluster chemical evolution, with significant increases among younger clusters. Last, cluster neutron-capture element abundances appear to be independent of Galactocentric distance. We conclude that a homogeneous analysis of a larger sample of open clusters is needed to resolve the apparent discrepant conclusions between different studies regarding s-process element abundance trends with age to better inform models of galactic chemical evolution.

  19. High index contrast hole-free photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Lipovskii, Andrey; Anan'ev, Anatoly; Maksimov, Leonid; Polukhin, Vladimir; Tagantsev, Dmitry; Tatarintsev, Boris

    2007-05-01

    A couple of multicomponent glasses was used to produce solid hole-free photonic crystal fiber (PCF) with high contrast of index. These glasses were a high index barium-lanthanum flint-glass (n~1.8) and a low index cron-glass (n~1.5). The compositions of selected glasses provided the coincidence of their viscosities in the temperature range of drawing, close thermal expansion coefficients, and chemical compatibility. To produce the PCF densely packed bundles of glass rods (elements) of 1 mm diameter assembled in a given structures were multiply co-drawn down to 0.2-2.0 microns diameter of a single element. This procedure allowed scaling of initial structures and resulted in two PCF structures: axially symmetrical eight-period structure and five-period "birefringent" structure. Optical transmission of the resultant PCF demonstrates the existence of photonic band-gaps, and intensity distribution of propagating mode corresponds to the results of numerical simulation performed.

  20. Improving bone cement toughness and contrast agent confinement by using acrylic branched polymers.

    PubMed

    Lissarrague, Maria H; Fascio, Mirta L; Goyanes, Silvia; D'Accorso, Norma B

    2016-02-01

    A new biomedical material to be used as part of acrylic bone cement formulations is described. This new material is tough, its Young's Modulus is similar to the one of poly (methylmethacrylate) and the contrast agent, usually employed in acrylic bone cements, is homogeneously distributed among the polymeric matrix. Additionally, its wear coefficient is 66% lower than the one measured in poly(methyl methacrylate). The developed material is a branched polymer with polyisoprene backbone and poly(methyl methacrylate) side chains, which are capable of retaining barium sulphate nanoparticles thus avoiding their aggregation. The grafting reaction was carried out in presence of the nanoparticles, using methyl methacrylate as solvent. From the (1)H-NMR spectra it was possible to determine the average number of MMA units per unit of isoprene (3.75:1). The ability to retain nanoparticles (about 8wt.%), attributed to their interaction with the polymer branches, was determined by thermogravimetric analysis and confirmed by FTIR and microscopy techniques. By SEM microscopy it was also possible to determine the homogeneous spatial distribution of the barium sulphate nanoparticles along the polymer matrix. PMID:26652446

  1. [Determination of trace barium in environmental samples by electric-heated AAS with lanthanum-coated graphite tube].

    PubMed

    Han, Hua-yun; Lin, Lin; Chen, Ke; Wang, Feng

    2002-02-01

    In this paper a new method was established for determination of trace barium in environmental samples by graphite furnace atomic absorption spectrometry. In the presence of matrix modifier magnesium nitrate, the matrix inference was eliminated efficiently. To avoid producing barium carbide, the graphite tubes were coated differently with lanthanum, zirconium, tungsten, molybdenum, and tantalum. Results showed that the tube with lanthanum was the best. The atomization temperature was diminished. The sensitivity was improved, and the tube with lanthanum gave the longest service life. So we used the tube to determine trace barium. The trace barium in Geodchemical Standard Reference Sample Soil-1 (GSS-1) was determined by the new method, the test results showed that the method was reliability and accurate. The method has been used for the determination of trace barium in environmental samples and in water of Yellow River. The detection limit for Ba was 2.1 x 10(-12) g and the relative standard deviation(RSD) was 5.4% for 15 ng.mL-1 Ba. PMID:12940053

  2. Comparative analysis of barium titanate thin films dry etching using inductively coupled plasmas by different fluorine-based mixture gas

    PubMed Central

    2014-01-01

    In this work, the inductively coupled plasma etching technique was applied to etch the barium titanate thin film. A comparative study of etch characteristics of the barium titanate thin film has been investigated in fluorine-based (CF4/O2, C4F8/O2 and SF6/O2) plasmas. The etch rates were measured using focused ion beam in order to ensure the accuracy of measurement. The surface morphology of etched barium titanate thin film was characterized by atomic force microscope. The chemical state of the etched surfaces was investigated by X-ray photoelectron spectroscopy. According to the experimental result, we monitored that a higher barium titanate thin film etch rate was achieved with SF6/O2 due to minimum amount of necessary ion energy and its higher volatility of etching byproducts as compared with CF4/O2 and C4F8/O2. Low-volatile C-F compound etching byproducts from C4F8/O2 were observed on the etched surface and resulted in the reduction of etch rate. As a result, the barium titanate films can be effectively etched by the plasma with the composition of SF6/O2, which has an etch rate of over than 46.7 nm/min at RF power/inductively coupled plasma (ICP) power of 150/1,000 W under gas pressure of 7.5 mTorr with a better surface morphology. PMID:25278821

  3. Multi-contrast photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Hu, S.; Sohn, R.; Lu, Z.-H.; Soetikno, B.; Zhong, Q.; Yao, J.; Maslov, K.; Arbeit, J. M.; Wang, L. V.

    2012-02-01

    We developed multi-contrast photoacoustic microscopy (PAM) for in vivo anatomical, functional, metabolic, and molecular imaging. This technical innovation enables comprehensive understanding of the tumor microenvironment. With multi-contrast PAM, we longitudinally determined tumor vascular anatomy, blood flow, oxygen saturation of hemoglobin, and oxygen extraction fraction.

  4. Faithful Contrastive Features in Learning

    ERIC Educational Resources Information Center

    Tesar, Bruce

    2006-01-01

    This article pursues the idea of inferring aspects of phonological underlying forms directly from surface contrasts by looking at optimality theoretic linguistic systems (Prince & Smolensky, 1993/2004). The main result proves that linguistic systems satisfying certain conditions have the faithful contrastive feature property: Whenever 2 distinct…

  5. Image Contrast in Holographic Reconstructions

    ERIC Educational Resources Information Center

    Russell, B. R.

    1969-01-01

    The fundamental concepts of holography are explained using elementary wave ideas. Discusses wavefront reconstruction and contrast in hemigraphic images. The consequence of recording only the intensity at a given surface and using an oblique reference wave is shown to be an incomplete reconstruction resulting in image of low contrast. (LC)

  6. Defect properties of cobalt-doped hexagonal barium titanate ceramics

    NASA Astrophysics Data System (ADS)

    Langhammer, H. T.; Böttcher, R.; Müller, T.; Walther, T.; Ebbinghaus, S. G.

    2015-07-01

    X-ray diffraction (XRD) patterns, electron paramagnetic resonance (EPR) powder spectra (9 and 34 GHz) and the magnetic susceptibility of BaTiO3 + 0.04 BaO + x/2 Co2O3 (0.001 ⩽ x ⩽ 0.02) ceramics were studied to investigate the incorporation of Co ions in the BaTiO3 lattice and their valence states as well as the development of the hexagonal phase (6H modification) in dependence on doping level x and sintering temperature Ts. At Ts = 1400 °C the 6H modification begins to occur at a nominal Co concentration x of about 0.001 and for x > 0.005 the samples are completely hexagonal at room temperature. Two different EPR spectra were observed in the 6H modification of BaTiO3, which were both assigned to paramagnetic Co2+ ions located at the two crystallographically non-equivalent Ti sites in 6H-BaTiO3. The EPR g tensor values as well as the molar paramagnetic susceptibility, measured in the temperature range 5 K-300 K at a magnetic field of 9 T, were analyzed in the framework of the ligand field theory using the program CONCORD. The combination of EPR and magnetic measurements reveals that in air-sintered 6H BaTiO3, the incorporated Co occurs as a mixture of paramagnetic Co2+ and diamagnetic Co3+ ions, whereas in samples annealed in reducing atmosphere the majority of Co is in the divalent state. The occurrence of Co4+ can be excluded for all investigated samples. The sample color caused by Co2+ and Co3+ ions is beige/light yellow and dark grey/black, respectively. The majority of the Co2+ ions substitutes Ti in the exclusively corner-sharing oxygen octahedra possessing nearly cubic symmetry. The corresponding ligand field parameter B04(3) amounts to about -28 000 cm-1 (Wybourne notation, 10Dq ≈ 20 000 cm-1). In the reduced samples nearly 5% of the detected Co2+ ions occupy the Ti site in the face-sharing oxygen octahedra, which are significantly trigonally distorted. The negative sign of the obtained ligand field parameter B02 ≈ -7300 cm-1

  7. Measurement of visual contrast sensitivity

    NASA Astrophysics Data System (ADS)

    Vongierke, H. E.; Marko, A. R.

    1985-04-01

    This invention involves measurement of the visual contrast sensitivity (modulation transfer) function of a human subject by means of linear or circular spatial frequency pattern on a cathode ray tube whose contrast is automatically decreasing or increasing depending on the subject pressing or releasing a hand-switch button. The threshold of detection of the pattern modulation is found by the subject by adjusting the contrast to values which vary about the subject's threshold thereby determining the threshold and also providing by the magnitude of the contrast fluctuations between reversals some estimate of the variability of the subject's absolute threshold. The invention also involves the slow automatic sweeping of the spatial frequency of the pattern over the spatial frequencies after preset time intervals or after threshold has been defined at each frequency by a selected number of subject-determined threshold crossings; i.e., contrast reversals.

  8. Barium in twilight zone suspended matter as a potential proxy for particulate organic carbon remineralization: Results for the North Pacific

    NASA Astrophysics Data System (ADS)

    Dehairs, F.; Jacquet, S.; Savoye, N.; Van Mooy, B. A. S.; Buesseler, K. O.; Bishop, J. K. B.; Lamborg, C. H.; Elskens, M.; Baeyens, W.; Boyd, P. W.; Casciotti, K. L.; Monnin, C.

    2008-07-01

    This study focuses on the fate of exported organic carbon in the twilight zone at two contrasting environments in the North Pacific: the oligotrophic ALOHA site (22°45'N, 158°W; Hawaii; studied during June-July 2004) and the mesotrophic Subarctic Pacific K2 site (47°N, 161°W; studied during July-August 2005). Earlier work has shown that non-lithogenic, excess particulate Ba (Ba xs) in the mesopelagic water column is a potential proxy of organic carbon remineralization. In general, Ba xs contents were significantly larger at K2 than at ALOHA. At ALOHA, the Ba xs profiles from repeated sampling (five casts) showed remarkable consistency over a period of three weeks, suggesting that the system was close to being at steady state. In contrast, more variability was observed at K2 (six casts sampled), reflecting the more dynamic physical and biological conditions prevailing in this environment. While for both sites Ba xs concentrations increased with depth, at K2 a clear maximum was present between the base of the mixed layer at around 50 and 500 m, reflecting production and release of Ba xs. Larger mesopelagic Ba xs contents and larger bacterial production in the twilight zone at the K2 site indicate that more material was exported from the upper mixed layer for bacterial degradation deeper, compared to the ALOHA site. Furthermore, application of a published transfer function [Dehairs, F., Shopova, D., Ober, S., Veth, C., Goeyens, L., 1997. Particulate barium stocks and oxygen consumption in the Southern Ocean mesopelagic water column during spring and early summer: relationship with export production. Deep-Sea Research II 44(1-2), 497-516] relating oxygen consumption to the observed Ba xs data indicated that the latter were in good agreement with bacterial respiration, calculated from bacterial production. These results corroborate earlier findings highlighting the potential of Ba xs as a proxy for organic carbon remineralization. The range of POC remineralization

  9. The chemistry of barium anomalies in the Berisal Complex, Simplon Region, Switzerland

    NASA Astrophysics Data System (ADS)

    Hetherington, Callum J.; Lundmark, Mattias; Graeser, Stefan; Gieré, Reto

    2008-02-01

    The petrographic and geochemical features of two zoisite-celsian gneiss outcrops from the Berisal Complex, characterised by a syn-kinematic mineral assemblage that contains celsian and barium white micas and a maximum whole-rock BaO content of 8.36 wt%, are described. The outcrops are enclosed in a larger body of garnet-bearing two-mica augen-gneiss, which has intrusive contacts with the surrounding garnet-biotite-muscovite paragneiss, and also contains small outcrops of two-mica clinozoisite gneiss. The zoisite-celsian gneisses are strongly enriched in all alkaline-earth elements, are depleted in the alkali elements, and have high Zr/Hf and Nb/Ta ratios compared with the surrounding gneisses. The zoisite-celsian, two-mica clinozoisite, and garnet-bearing two-mica augen-gneisses have Al/CNK molar ratios >1, and the zoisite-celsian gneisses are also enriched in Zr, Y, and Nb. Chondrite-normalised patterns for the rare earth elements (REE) show light REE enrichment, with a negative Eu anomaly. On the basis of field and geochemical data it is argued that the barium anomalies in the Berisal complex are the result of igneous fractionation of barium into anorthosite-dominated cognate inclusions within a larger volume of calc-alkaline peraluminous melt. On the basis of U-Pb zircon ages, a conservative estimate for the age of magma crystallisation is placed at 460 ± 10 Ma, and thus was related to significant late Ordovician granitoid magmatism in Gondwana-derived microcontinents during collision between Avalonia-Cadomia and Gondwana.

  10. Bimodal chemical evolution of the Galactic disk and the Barium abundance of Cepheids

    NASA Astrophysics Data System (ADS)

    Lépine, Jacques R. D.; Andrievky, Sergei; Barros, Douglas A.; Junqueira, Thiago C.; Scarano, Sergio

    2014-01-01

    In order to understand the Barium abundance distribution in the Galactic disk based on Cepheids, one must first be aware of important effects of the corotation resonance, situated a little beyond the solar orbit. The thin disk of the Galaxy is divided in two regions that are separated by a barrier situated at that radius. Since the gas cannot get across that barrier, the chemical evolution is independent on the two sides of it. The barrier is caused by the opposite directions of flows of gas, on the two sides, in addition to a Cassini-like ring void of HI (caused itself by the flows). A step in the metallicity gradient developed at corotation, due to the difference in the average star formation rate on the two sides, and to this lack of communication between them. In connection with this, a proof that the spiral arms of our Galaxy are long-lived (a few billion years) is the existence of this step. When one studies the abundance gradients by means of stars which span a range of ages, like the Cepheids, one has to take into account that stars, contrary to the gas, have the possibility of crossing the corotation barrier. A few stars born on the high metallicity side are seen on the low metallicity one, and vice-versa. In the present work we re-discuss the data on Barium abundance in Cepheids as a function of Galactic radius, taking into account the scenario described above. The [Ba/H] ratio, plotted as a function of Galactic radius, apparently presents a distribution with two branches in the external region (beyond corotation). One can re-interpret the data and attribute the upper branch to the stars that were born on the high metallicity side. The lower branch, analyzed separately, indicates that the stars born beyond corotation have a rising Barium metallicity as a function of Galactic radius.

  11. Hydrothermal Synthesis and Processing of Barium Titanate Nanoparticles Embedded in Polymer Films.

    PubMed

    Toomey, Michael D; Gao, Kai; Mendis, Gamini P; Slamovich, Elliott B; Howarter, John A

    2015-12-30

    Barium titanate nanoparticles embedded in flexible polymer films were synthesized using hydrothermal processing methods. The resulting films were characterized with respect to material composition, size distribution of nanoparticles, and spatial location of particles within the polymer film. Synthesis conditions were varied based on the mechanical properties of the polymer films, ratio of polymer to barium titanate precursors, and length of aging time between initial formulations of the solution to final processing of nanoparticles. Block copolymers of poly(styrene-co-maleic anhydride) (SMAh) were used to spatially separate titanium precursors based on specific chemical interactions with the maleic anhydride moiety. However, the glassy nature of this copolymer restricted mobility of the titanium precursors during hydrothermal processing. The addition of rubbery butadiene moieties, through mixing of the SMAh with poly(styrene-butadiene-styrene) (SBS) copolymer, increased the nanoparticle dispersion as a result of greater diffusivity of the titanium precursor via higher mobility of the polymer matrix. Additionally, an aminosilane was used as a means to retard cross-linking in polymer-metalorganic solutions, as the titanium precursor molecules were shown to react and form networks prior to hydrothermal processing. By adding small amounts of competing aminosilane, excessive cross-linking was prevented without significantly impacting the quality and composition of the final barium titanate nanoparticles. X-ray diffraction and X-ray photoelectron spectroscopy were used to verify nanoparticle compositions. Particle sizes within the polymer films were measured to be 108 ± 5 nm, 100 ± 6 nm, and 60 ± 5 nm under different synthetic conditions using electron microscopy. Flexibility of the films was assessed through measurement of the glass transition temperature using dynamic mechanical analysis. Dielectric permittivity was measured using an impedance analyzer. PMID

  12. Small-scale fluctuations in barium drifts at high latitudes and associated Joule heating effects

    NASA Astrophysics Data System (ADS)

    Hurd, L. D.; Larsen, M. F.

    2016-01-01

    Most previous estimates of Joule heating rates, especially the contribution of small-scale structure in the high-latitude ionosphere, have been based on incoherent scatter or coherent scatter radar measurements. An alternative estimate can be found from the plasma drifts obtained from ionized barium clouds released from sounding rockets. We have used barium drift data from three experiments to estimate Joule heating rates in the high-latitude E region for different magnetic activity levels. In particular, we are interested in the contribution of small-scale plasma drift fluctuations, corresponding to equivalent electric field fluctuations, to the local Joule heating rate on scales smaller than those typically resolved by radar or other measurements. Since Joule heating is a Lagrangian quantity, the inherently Lagrangian estimates provided by the chemical tracer measurements are a full description of the effects of electric field variance and neutral winds on the heating, differing from the Eulerian estimates of the type provided by ground-based measurements. Results suggest that the small-scale contributions to the heating can be more than a factor of 2 greater than the mean field contribution regardless of geomagnetic conditions, and at times the small-scale contribution is even larger. The high-resolution barium drift measurements, moreover, show that the fine structure in the electric field can be more variable than previous studies have reported for similar conditions. The neutral winds also affect the heating, altering the height-integrated Joule heating rates by as much as 12%, for the cases studied here, and modifying the height distribution of the heating profile as well.

  13. Contrasting Rhetorics/Contrasting Cultures: Why Contrastive Rhetoric Needs a Better Conceptualization of Culture

    ERIC Educational Resources Information Center

    Atkinson, Dwight

    2004-01-01

    This paper deals with an underdeveloped notion in the EAP sub-discipline of contrastive rhetoric: culture. It argues that a better conceptualization of contrastive rhetoric needs to include a better conceptualization of culture. After engaging with the complex question "What is culture?" the paper moves on to consider four sets of current issues…

  14. Studies in the reaction-separation method for the preparation of barium chloride from barite using ion exchange

    SciTech Connect

    Gokarn, A.N.; Gaikwad, A.G.; Phalak, C.A.; Bhandari, V.M.

    1999-06-01

    The authors report the application of an ion-exchange process as a reaction-separation strategy for the preparation of barium chloride from barite ore and sodium chloride. Experimental studies were carried out to evaluate the process efficiency and purity/yield of barium chloride using a strong acid cation-exchange resin, Tulsion T-42. The effects of various process parameters such as concentration of barium sulfide and concentration of sodium chloride were investigated, and optimization of the experimental variables was attempted. The results indicate the developed strategy to be attractive and an alternative route to existing processes. The methodology developed has large potential for the inorganic chemical process industry in general.

  15. Detection of the barium daughter in 136Xe -->136Ba + 2e- by in situ single-molecule fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Nygren, David

    2015-10-01

    To proceed toward effective ``discovery class'' ton-scale detectors in the search for neutrino-less double beta decay, a robust technique for rejection of all radioactivity-induced backgrounds is urgently needed. An efficient technique for detection of the barium daughter in the decay 136Xe -->136Ba + 2e- would provide a long-sought pathway toward this goal. Single-molecule fluorescent imaging appears to offer a new way to detect the barium daughter atom, which emerges naturally in an ionized state in pure xenon. A doubly charged barium ion can initiate a chelation process with a non-fluorescent precursor molecule, leading to a highly fluorescent complex. Repeated photo-excitation of the complex can reveal both presence and location of a single ionized atom with high precision and selectivity. Detection within the active volume of a xenon gas Time Projection Chamber operating at high pressure would be automatic, and with a capability for redundant confirmation.

  16. Bioaccessibility of barium from barite contaminated soils based on gastric phase in vitro data and plant uptake.

    PubMed

    Abbasi, Sedigheh; Lamb, Dane T; Palanisami, Thavamani; Kader, Mohammed; Matanitobua, Vitukawalu; Megharaj, Mallavarapu; Naidu, Ravi

    2016-02-01

    Barite contamination of soil commonly occurs from either barite mining or explorative drilling operations. This work reported in vitro data for barite contaminated soils using the physiologically based extraction test (PBET) methodology. The existence of barite in plant tissue and the possibility of 'biomineralised' zones was also investigated using Scanning Electron Microscopy. Soils with low barium (Ba) concentrations showed a higher proportion of Ba extractability than barite rich samples. Barium uptake to spinach from soil was different between short term spiking studies and field weathered soils. Furthermore, Ba crystals were not evident in spinach tissue or acid digest solutions grown in barium nitrate spiked soils despite high accumulation. Barite was found in the plant digest solutions from barite contaminated soils only. Results indicate that under the conservative assumptions made, a child would need to consume extreme quantities of soil over an extended period to cause chronic health problems. PMID:26495826

  17. Ab initio study of the ferroelectric strain dependence and 180∘ domain walls in the barium metal fluorides BaMgF4 and BaZnF4

    NASA Astrophysics Data System (ADS)

    Núñez Valdez, Maribel; Spanke, Hendrik Th.; Spaldin, Nicola A.

    2016-02-01

    We investigate the strain dependence of the ferroelectric polarization and the structure of the ferroelectric domain walls in the layered perovskite-related barium fluorides, Ba M F4 (M =Mg , Zn). The unusual "geometric ferroelectricity" in these materials is driven by the softening of a single polar phonon mode consisting of rotations of the M F6 octahedra accompanied by polar displacements of the Ba cations, and in contrast to conventional ferroelectrics involves minimal electronic rehybridization. We therefore anticipate a different strain dependence of the polarization, and alternative domain wall structures compared with those found in conventional ferroelectric materials. Using first-principles calculations based on density functional theory (DFT) within the general gradient approximation (GGA), we calculate the variation of the crystal structure and the ferroelectric polarization under both compressive and tensile strain. We perform structural relaxations of neutral domain walls between oppositely oriented directions of the ferroelectric polarization and calculate their corresponding energies to determine which are most likely to form. We compare our results to literature values for conventional perovskite oxides to provide a source of comparison for understanding the ferroelectric properties of alternative nonoxide materials such as the barium fluorides.

  18. The structure and dielectric properties of thin barium zirconate titanate films obtained by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tumarkin, A. V.; Razumov, S. V.; Gagarin, A. G.; Altynnikov, A. G.; Stozharov, V. M.; Kaptelov, E. Yu.; Senkevich, S. V.; Pronin, I. P.

    2016-02-01

    Submicron thin layers of BaZr x Ti1- x O3 are grown in-situ by RF magnetron sputtering of a ceramic target ( x = 0.50) on a substrate of Pt/ r-cut leucosapphire Al2O3. It is shown that the composition of the ferroelectric layer is not identical to the composition of the sputtered target and is shifted toward barium zirconate. The reasons for such behavior are discussed. The obtained samples are characterized by high breakdown voltages (1 MV/cm and higher). The structural and high-frequency dielectric properties are studied, and high tunability of the capacitance of thin layers is revealed.

  19. Non-aqueous titration of quinine and quinidine sulphates by use of barium perchlorate.

    PubMed

    Zakhari, N; Ibrahim, F; Kovar, K A

    1989-07-01

    A simple non-aqueous titration method has been devised for determining the sulphates of quinine and quinidine. The sulphate is precipitated by addition of excess of barium perchlorate solution in acetic and the liberated alkaloid is then titrated in 1:2 anhydrous acetic-dioxan mixture, with an acetic acid solution of perchloric acid. The end-point is determined either visually with Crystal Violet as indicator or potentiometrically with a glass-Ag/AgCl combination electrode. The method is accurate, precise and suitable for routine analysis of pure materials and tablets. PMID:18964803

  20. Three-wave mixing mediated femtosecond pulse compression in β-barium borate.

    PubMed

    Grün, A; Austin, Dane R; Cousin, Seth L; Biegert, J

    2015-10-15

    Nonlinear pulse compression mediated by three-wave mixing is demonstrated for ultrashort Ti:sapphire pulses in a type II phase-matched β-barium borate (BBO) crystal using noncollinear geometry. 170 μJ pulses at 800 nm with a pulse duration of 74 fs are compressed at their sum frequency to 32 fs with 55 μJ of pulse energy. Experiments and computer simulations demonstrate the potential of sum-frequency pulse compression to match the group velocities of the interacting waves to crystals that were initially not considered in the context of nonlinear pulse compression. PMID:26469593

  1. Strain effect on coercive field of epitaxial barium titanate thin films

    NASA Astrophysics Data System (ADS)

    Choudhury, S.; Li, Y. L.; Chen, L. Q.; Jia, Q. X.

    2008-04-01

    Strain is generally known to increase the coercive field of a ferroelectric thin film as compared to a stress-free single crystal or a strain-relaxed film. We studied the coercive fields and remanent polarizations of (001)-oriented epitaxial barium titanate thin films using the phase-field approach. It is demonstrated, while the remanent polarization decreases as in-plane strain changes from being compressive to tensile, the variation of coercive field with strain is complicated. We noted more than two times drop in coercive field with a reduction of compressive strain of only ˜0.05%, which we attribute to the existence of multiple ferroelectric phases.

  2. Lead-barium fluoroborate glass ceramics doped with Nd3+ or Er3+

    NASA Astrophysics Data System (ADS)

    Petrova, O. B.; Sevostjanova, T. S.; Anurova, M. O.; Khomyakov, A. V.

    2016-02-01

    Lead-barium fluoroborate glasses in the PbF2-BaF2-B2O3, PbF2-BaO-B2O3, and PbO- BaF2-B2O3 systems doped with rare-earth ions (Nd3+ or Er3+) are synthesized and studied. It is shown that, based on these glasses, it is possible to produce transparent glass ceramics with fluoride crystalline phases, including ceramics with one crystalline phase of the fluorite structure. The spectral and luminescent properties of the doped glasses, glass ceramics, and polycrystalline complex fluorides containing Pb, Ba, and rare ions are studied.

  3. Growth and Vibrational Spectroscopic Investigations of NLO Crystal Barium Thiourea Chloride

    NASA Astrophysics Data System (ADS)

    Kumari, M. Meena; Ravikumar, C.; Amalanathan, M.; Jayakumar, V. S.; Joe, I. Hubert

    2008-11-01

    The crystal of NLO interest, Barium thiourea chloride (BTC) has been crystallized and is subjected to FT-IR and NIR FT-Raman spectral studies along with the quantum chemical computations. The equilibrium geometry, first hyperpolarizability, various bonding features and vibrational wavenumbers have been calculated by B3LYP density functional theory (DFT) calculations at the LANL2DZ level. The predicted vibrational spectra are in fair agreement with the experiment. The broadening of NH2 stretching wavenumber indicates the intermolecular N-H…CI hydrogen bonding present in the molecule.

  4. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    NASA Astrophysics Data System (ADS)

    Raj, S. Gokul; Mathivanan, V.; Kumar, G. Ramesh; Yathavan, S.; Mohan, R.

    2016-05-01

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr0.6B0.4Nb2O6) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce+ ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  5. Fabrication of flexible magnetic papers based on bacterial cellulose and barium hexaferrite with improved mechanical properties

    NASA Astrophysics Data System (ADS)

    Lim, Guh-Hwan; Lee, Jooyoung; Kwon, Nayoung; Bok, Shingyu; Sim, Hwansu; Moon, Kyoung-Seok; Lee, Sang-Eui; Lim, Byungkwon

    2016-08-01

    We report on a simple approach to fabricate mechanically robust magnetic cellulose papers containing M-type barium hexaferrite (BaFe12O19) nanoplates. BaFe12O19 nanoplates were synthesized by a hydrothermal method and then chemically functionalized by using a silane coupling agent. The magnetic cellulose papers prepared with the silane-treated BaFe12O19 nanoplates exhibited improved mechanical properties with tensile strength of 58.5 MPa and Young's modulus of 2.95 GPa. [Figure not available: see fulltext.

  6. Absorption spectrum of the laser-populated 3D metastable levels in barium

    NASA Technical Reports Server (NTRS)

    Carlsten, J. L.; Mcilrath, T. J.; Parkinson, W. H.

    1975-01-01

    This paper deals with the details of the absorption spectrum of the 3D metastable term in barium. The 3D term was selectively populated with a tuneable dye laser. The fundamental triplet series (6s5d 3D-6snf 3F) is identified and extended out to n = 32. In addition, the absolute photoionization cross section was measured at 303 nm. The relative cross section from 303 to 250 nm was also measured with the absolute scale set by the measurement at 303 nm and was found to be nearly constant in the wavelength region measured.

  7. R-matrix study of ionization in barium via two-photon interfering routes

    NASA Astrophysics Data System (ADS)

    Aymar, M.; Luc-Koenig, E.; Lecomte, J. M.; Millet, M.; Lyras, A.

    2000-02-01

    A quantitative analysis of part of the experimental data reported by Wang, Chen and Elliott [1,3] who studied in barium coherent control through two-color resonant interfering paths is reported. Dynamics of the two-color photoionization process, described as an adiabatic process in the rotating wave approximation, is governed by the coherent excitation of the 6s6p and 6s7p 1P1 intermediate states. Interference effects are found to play a minor role. The required atomic parameters are obtained from a theoretical approach based on a combination of jj-coupled eigenchannel R-matrix and Multichannel Quantum Defect Theory.

  8. Study of the structure of ferroelectric domain walls in barium titanate ceramics

    SciTech Connect

    Normand, L.; Thorel, A.; Kilaas, R.; Montardi, Y.

    1995-02-01

    Structure of 90{degree} ferroelectric domain boundaries in barium titanate ceramics has been studied by means of Transmission Electron Microscopy and High Resolution TEM. Tilts of specific fringes across domain walls are measured on HREM images and Selected Area Diffraction Patterns. They are in a good agreement with the twin model admitted for these domain boundaries. A computerized method has been developed to give access to quantitative information about atomic displacements across these ferroelectric domain walls. The so calculated displacement field is then compared with Landau-Ginzburg based theoretical predictions.

  9. Investigation Of Dispersive Conductivity And Dielectric Losses In Barium Bismuth Silicate Glasses

    NASA Astrophysics Data System (ADS)

    Ahlawat, Neetu; Sanghi, Sujata; Agarwal, Ashish; Ahlawat, Navneet; Aghamkar, Praveen; Monica

    2011-12-01

    Barium bismuth silicate glasses (BBS glasses) with composition were prepared by normal melt quench technique. The dispersive conductivity and dielectric losses in these glasses were investigated by impedance spectroscopy. The analyses of ac conductivity spectra show a crossover from ion hopping conductivity to nearly constant loss (NCL) contribution in all the glasses. The variations in dielectric constant ɛ*(ω) = ɛ'(ω)-íɛ″(ω) with frequency and temperature indicate an increase in electrode polarization, which reduces the dipolar relaxation effects in these glasses. The increased concentration of BaO in the glass composition reduces the dielectric losses in the present glasses.

  10. Complications of barium enema examinations: a survey of UK Consultant Radiologists 1992 to 1994.

    PubMed

    Blakeborough, A; Sheridan, M B; Chapman, A H

    1997-02-01

    Questionnaires were sent to all Consultant Radiologists in the UK regarding complications from barium enema examinations. The 756 respondents performed a total of 738,216 examinations over the three year period 1992 to 1994. Seventy-seven Consultants (10.2%) reported a total of 82 complications including 13 deaths: an overall mortality rate of 1 in 56,786. Only three of 30 (10%) cases of bowel perforation died, as compared with nine out of 16 (56%) cases of cardiac arrhythmia. The only remaining death was a consequence of vaginal intubation. Details of all the reported complications are recorded. This was an entirely retrospective study. PMID:9043049

  11. Investigating the effect of V2O5 addition on sodium barium borosilicate glasses

    NASA Astrophysics Data System (ADS)

    Halder, Rumu; Sengupta, Pranesh; Sudarsan, V.; Kaushik, C. P.; Dey, G. K.

    2016-05-01

    V2O5 doped sodium barium borosilicate glasses were characterized by photoluminescence spectroscopy and electron probe microanalyzer (EPMA). The glass remains homogeneous for lower concentration of V2O5 but a phase separation is observed when V2O5 doping is increased beyond 5 mol%. Detailed microanalysis reveals that the phase separated glass consists of a phase containing V, Ba and Si and a separate Si rich phase within the glass matrix. The luminescence study demonstrated that at low concentration the vanadium mainly interacts with the structural units of B/Si while at higher concentrations, V-O-V/ V-O- Na+/Ba2+ linkages are formed.

  12. Study of optical properties of cerium ion doped barium aluminate phosphor

    NASA Astrophysics Data System (ADS)

    Lohe, P. P.; Omanwar, S. K.; Bajaj, N. S.; Belsare, P. D.

    2016-05-01

    In the recent years due to their various optical and technological applications aluminate materials have attracted attention of several researchers. When these materials are doped with rare earth ions they show properties favorable for many optical applications such as high quantum efficiencies. These materials are used in various applications such as lamp phosphors, optically and thermoluminescence dosimeter etc Barium aluminate BaAl2O4 doped with Ce is well known long lasting phosphor. This paper reports synthesis of BaAl2O4: Ce phosphor prepared by a simple combustion synthesis. The samples were characterized for the phase purity, chemical bonds and luminescent properties.

  13. Enhancement of Curie temperature of barium hexaferrite by dense electronic excitations

    SciTech Connect

    Sharma, Manju; Kashyap, Subhash C.; Gupta, Hem C.; Dimri, Mukesh C.; Asokan, K.

    2014-07-15

    Curie temperature of polycrystalline barium hexaferrite (BaFe{sub 12}O{sub 19}), prepared by conventional solid state technique, is anomalously and significantly enhanced (by nearly 15%) by energetic heavy ion irradiation (150 MeV, Ag{sup 12+}) at ambient temperature due to dense electronic excitations Moderate fluence (1 × 10{sup 12} ions/cm{sup 2}) induces structural defects giving rise to above enhancement. As established by X-ray diffraction, scanning electron microscopy and Raman studies, higher fluence (1 × 10{sup 13} ions/cm{sup 2}) has structurally transformed the sample to amorphous phase with marginal change in magnetization and Curie temperature.

  14. Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

    SciTech Connect

    Trull, J.; Wang, B.; Parra, A.; Vilaseca, R.; Cojocaru, C.; Sola, I.; Sheng, Y.

    2015-06-01

    Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.

  15. Direct writing of ferroelectric domains on strontium barium niobate crystals using focused ultraviolet laser light

    SciTech Connect

    Boes, Andreas; Crasto, Tristan; Steigerwald, Hendrik; Mitchell, Arnan; Wade, Scott; Frohnhaus, Jakob; Soergel, Elisabeth

    2013-09-30

    We report ferroelectric domain inversion in strontium barium niobate (SBN) single crystals by irradiating the surface locally with a strongly focused ultraviolet (UV) laser beam. The generated domains are investigated using piezoresponse force microscopy. We propose a simple model that allows predicting the domain width as a function of the irradiation intensity, which indeed applies for both SBN and LiNbO{sub 3}. Evidently, though fundamentally different, the domain structure of both SBN and LiNbO{sub 3} can be engineered through similar UV irradiation.

  16. Effect of samarium doping on the dielectric behavior of barium zircomium titanate ceramic

    SciTech Connect

    Badapanda, T.; Sarangi, S.; Behera, B.; Anwar, S.; Sinha, T. P.

    2014-04-24

    Samarium doped Barium Zirconium Titanate ceramic with general formula Ba{sub 1−x}Sm{sub 2x/3}Zr{sub 0.05}Ti{sub 0.95}O{sub 3} [x=0.0,0.01,0.02,0.03,0.04] has been prepared by high energy ball milling. The X-ray diffraction (XRD) patterns confirmed that these ceramics have a single phase with perovskite-type upto x≤0.03 and a small secondary phase exist at x=0.04. The temperature dependent dielectric study shows a ferroelectric phase transition and transition temperature decreases with an increase in the Samarium content.

  17. The Skylab barium plasma injection experiments. II - Evidence for a double layer

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hallinan, T. J.; Davis, T. N.; Peek, H. M.

    1976-01-01

    Television observations of a barium-plasma flux tube extending from near 4500 km to near 10,000 km during a magnetic substorm and dawn-sector auroral display indicated several interesting anomalous events. Beyond 5500 km, there was a rapid increase in brightness accompanied by flux-tube splitting and diffusion, leaving behind a truncated single flux tube. From the orientation of the flux tube compared with theoretical field models, the presence of a substantial field-aligned current sheet is deduced. A suggested explanation of these phenomena is given in terms of a plasma potential double layer.

  18. Effects of disorder on properties of non-conventionally prepared barium titanate

    SciTech Connect

    Banerjee, A.; Sarkar, S.; Roychowdhury, A.; Das, D.

    2015-06-24

    Barium titanaten (BaTiO{sub 3}) nanoparticles were prepared by non-conventional as well as conventional solid state reaction. A better response about the grain size distribution was obtained in the former. The former was then milled to get grains of successive reduced sizes. The defects induced within the samples were studies by positron annihilation spectroscopy. The effect of defects on dielectric property of sample with finest grains was measured. Dielectric stability with temperature was increased with decreasing grain size and the peak was shifted towards the lower value due to the enhancement of grain boundary defects generated due to milling for long time.

  19. A small-scale plasmoid formed during the May 13, 1985, AMPTE magnetotail barium release

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Fritz, T. A.; Bernhardt, P. A.

    1989-01-01

    Plasmoids are closed magnetic-loop structures with entrained hot plasma which are inferred to occur on large spatial scales in space plasma systems. A model is proposed here to explain the brightening and rapid tailward movement of the barium cloud released by the AMPTE IRM spacecraft on May 13, 1985. The model suggests that a small-scale plasmoid was formed due to a predicted development of heavy-ion-induced tearing in the thinned near-tail plasma sheet. Thus, a plasmoid may actually have been imaged due to the emissions of the entrained plasma ions within the plasma bubble.

  20. Efficient ionisation of calcium, strontium and barium by resonant laser pumping

    NASA Technical Reports Server (NTRS)

    Skinner, C. H.

    1980-01-01

    Efficient ionization has been observed when an atomic vapor of strontium, barium or calcium was illuminated with a long pulse tunable laser at the frequency of the atomic resonance line. The variation in the degree of ionization with neutral density and laser intensity has been measured using the 'hook' method. The maximum ionization observed was 94%. Excited state populations were measured yielding an excitation temperature (depending on exact experimental conditions) in the region of 0.4 eV. The decay of ion density after the laser pulse was monitored and the recombination coefficients determined. The results are interpreted in terms of an electron heating model.

  1. Barium hydroxyapatite nanoparticles synthesized by citric acid sol-gel combustion method

    SciTech Connect

    Xiu Zhiliang; Lue Mengkai . E-mail: mklu@icm.sdu.edu.cn; Liu Suwen; Zhou Guangjun; Su Benyu; Zhang Haiping

    2005-09-01

    Barium hydroxyapatite (BaHAP) nanoparticles have been synthesized by citric acid sol-gel combustion method using citric acid as a reductant/fuel and nitrate as an oxidant at a relatively low temperature of 600 deg. C. The thermal decomposition of nitrate-citrate xerogel was investigated by thermogravimetric/differential thermal analysis (TG/DTA) technique. The yielding powders calcined at 600 deg. C have been characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and transmission electron microscope (TEM). The possible combustion process was presented.

  2. DANCE : a 4[pi] barium fluoride detector for measuring neutron capture on unstable nuclei /.

    SciTech Connect

    Ullmann, J. L.; Haight, Robert C.; Hunt, L. F.; Reifarth, R.; Rundberg, R. S.; Bredeweg, T. A.; Fowler, Malcolm M.; Miller, G. G.; Heil, M.; Käppeler, F.; Chamberlin, E. P.

    2002-01-01

    Measurements of neutron capture on unstable nuclei are important for studies of s-process nucleosynthesis, nuclear waste transmutation, and stewardship science. A 160-element, 4{pi} barium fluoride detector array, and associated neutron flight path, is being constructed to make capture measurements at the moderated neutron spallation source at LANSCE. Measurements can be made on as little as 1 mg of sample material over energies from near thermal to near 100 keV. The design of the DANCE array is described and neutron flux measurements from flight path commissioning are shown. The array is expected to be complete by the end of 2002.

  3. Improvement of the thermal properties of a polystyrene via inclusion of barium hexaferrite particles

    NASA Astrophysics Data System (ADS)

    Hemeda, O. M.; El-Sayed, Adly H.; Tawfik, A.; Hamad, Mahmoud A.

    2016-07-01

    M-type barium hexaferrite (BaM) particles–polystyrene (PS) composite has been successfully synthesized. Fourier transform infrared spectra confirm the synthesis of the BaM–PS composite. Scanning electron microscopy shows that BaM particles are attached rather well to the PS matrix and have variable sizes and shapes. Differential and thermogravimetric analysis indicate that PS chains are well coupled within the BaM powder and the thermal stability of PS is enhanced by incorporating BaM in the PS matrix.

  4. Molecular dynamics of poly(ethylene terephthalate)/poly(phenylene sulfide) nanocomposites with barium titanate

    NASA Astrophysics Data System (ADS)

    Konieczna, Monika; Woźniak-Braszak, Aneta; Hołderna-Natkaniec, Krystyna; Jurga, Jan

    2011-04-01

    The relaxation processes and the properties of polymer/ceramic nanocomposites have been studied by the 1H nuclear magnetic resonance methods. Nanocomposites of poly(ethylene terephthalate) PET and poly(phenylene sulfide) PPS with 0.25, 2.5 and 5% wt. barium titanate BT were prepared using a twin screw extruder and injection moulding machine. The spin-lattice relaxation time T1, second moment M2 and the motional parameters as e.g. the activation energies in the nanocomposites were investigated.

  5. Thermionic electron emission microscopy studies of barium and scandium oxides on tungsten

    NASA Astrophysics Data System (ADS)

    Vaughn, Joel M.

    Scandate dispenser cathodes have demonstrated an immense improvement in current densities for thermionic cathodes. However, the emission properties are inconsistent from cathode to cathode. The cathodes also lack the lifetime desired for space based applications. Further scientific investigation of the reason for the increased electron emission and limited life is needed to solve the manufacturing inconsistencies and limited lifetimes. Radio frequency magnetron sputter deposited thin film squares (25 x 25 mum and 100 x 100 mum) of barium, scandium and the oxides of both were prepared in a variety of configurations on tungsten and scandium foils for study and characterization of electron yield in a photoelectron emission and thermionic electron emission microscope (PEEM/ThEEM) fitted with a Faraday cup for current density measurements. The samples were studied from a room temperature to brightness temperatures in excess of 1600 K. It was determined that sub-monolayer oxide coverage is not necessary for increased current densities. It was discovered that application of a 200 nm thin film of scandium oxide increases the electron yield of tungsten, and the increased yield is dependent on the interface between these two materials. Barium oxide on top of scandium oxide also increased the electron yield. Both barium and scandium metal wet the surface of tungsten, and thus their physical position cannot be controlled. Barium oxide and scandium oxide, however, presented physical stability to brightness temperatures of 1600 K and above. A model is presented, using data acquired from ThEEM, UPS and TES, explaining the increased electron yield and transport through thick oxide layers. The model proposes electron injection from tungsten into a gap state in scandium oxide. This gap state is above the lowest occupied orbital, and is proposed to be in the 3d electron levels of scandium. Electrons in the gap state are then free to move to the surface, where they have an effectively

  6. The molecular structure of barium dibromide: an electron diffraction and quantum chemical study

    NASA Astrophysics Data System (ADS)

    Hargittai, Magdolna; Kolonits, Mária; Schultz, György

    2001-06-01

    The molecular structure of barium dibromide was determined by gas-phase electron diffraction, ab initio quantum chemical calculations, and joint electron diffraction/vibratonal spectroscopic analyses. All techniques yield consistently an unambiguously bent geometry. The following geometrical parameters were obtained: rg(Ba-Br) 2.911±0.006 Å, re(Ba-Br) 2.899±0.007 Å, ∠ aBr-Ba-Br 137.0±2.5° and ∠ eBr-Ba-Br 137.1±4.9°.

  7. Crystal growth, morphology, spectrographic characterization and thermal properties of Glycine Barium Bromo Chloride crystals

    NASA Astrophysics Data System (ADS)

    Arularasan, P.; Thayanithi, V.; Mohan, R.

    2015-06-01

    Glycine Barium Bromo Chloride material was purified by repeated recrystallization. Single crystal was grown by the slow evaporation solution technique (SEST). The presence of functional groups in the grown crystals was confirmed by Fourier transform infrared spectrum analysis. Thermal properties of the crystals were investigated using thermogravimetric (TG) and differential thermal analyses (DTA). The dielectric studies were carried out to identify the phase transition temperature and the dielectric constant was found. The transparency of crystal was tested using UV-visible spectra. Single crystal X-ray diffraction study has been carried out to find the crystal system and unit cell parameters.

  8. Fluorine contamination in yttrium-doped barium zirconate film deposited by atomic layer deposition

    SciTech Connect

    An Jihwan; Beom Kim, Young; Sun Park, Joong; Hyung Shim, Joon; Guer, Turgut M.; Prinz, Fritz B.

    2012-01-15

    The authors have investigated the change of chemical composition, crystallinity, and ionic conductivity in fluorine contaminated yttrium-doped barium zirconate (BYZ) fabricated by atomic layer deposition (ALD). It has been identified that fluorine contamination can significantly affect the conductivity of the ALD BYZ. The authors have also successfully established the relationship between process temperature and contamination and the source of fluorine contamination, which was the perfluoroelastomer O-ring used for vacuum sealing. The total removal of fluorine contamination was achieved by using all-metal sealed chamber instead of O-ring seals.

  9. Diamagnetic cavitization of laser-produced barium plasma in transverse magnetic field.

    PubMed

    Raju, Makaraju Srinivasa; Singh, R K; Kumar, Ajai; Gopinath, Pramod

    2015-05-15

    Influence of uniform transverse magnetic field and ambient Ar pressure on the plasma plume produced by Nd:YAG laser ablation of barium has been investigated by time-of-flight optical emission spectroscopy. Experiments were carried out with laser pulse energy of 150 mJ and 0.45 Tesla magnetic field. The time-of-flight profiles showed ambient pressure independent behavior at 6-mm distance from the target, which is attributed to the diamagnetic behavior of the laser plasma. A theoretical model is proposed that may explain the compression of temporal profiles of the ionic lines. PMID:26393695

  10. Comparison of Barium and Amorphous Boron Pyrotechnics for Green Light Emission

    NASA Astrophysics Data System (ADS)

    Poret, Jay C.; Sabatini, Jesse J.

    2013-01-01

    A comparison of green light emission from both barium- and amorphous boron-based pyrotechnics is described. Emission spectra are shown for both the U.S. Army in-service M125A1 green star cluster formulation and an amorphous boron-potassium nitrate-binder formulation. The main peaks of the emission spectra, average dominant wavelength, and average spectral purity of both formulations are given. The role that combustion products play in determining flame temperature and continuum radiation is also discussed.

  11. Ultrasound Despeckling for Contrast Enhancement

    PubMed Central

    Tay, Peter C.; Garson, Christopher D.; Acton, Scott T.; Hossack, John A.

    2010-01-01

    Images produced by ultrasound systems are adversely hampered by a stochastic process known as speckle. A despeckling method based upon removing outlier is proposed. The method is developed to contrast enhance B-mode ultrasound images. The contrast enhancement is with respect to decreasing pixel variations in homogeneous regions while maintaining or improving differences in mean values of distinct regions. A comparison of the proposed despeckling filter is compared with the other well known despeckling filters. The evaluations of despeckling performance are based upon improvements to contrast enhancement, structural similarity, and segmentation results on a Field II simulated image and actual B-mode cardiac ultrasound images captured in vivo. PMID:20227984

  12. Ultrasound despeckling for contrast enhancement.

    PubMed

    Tay, Peter C; Garson, Christopher D; Acton, Scott T; Hossack, John A

    2010-07-01

    Images produced by ultrasound systems are adversely hampered by a stochastic process known as speckle. A despeckling method based upon removing outlier is proposed. The method is developed to contrast enhance B-mode ultrasound images. The contrast enhancement is with respect to decreasing pixel variations in homogeneous regions while maintaining or improving differences in mean values of distinct regions. A comparison of the proposed despeckling filter is compared with the other well known despeckling filters. The evaluations of despeckling performance are based upon improvements to contrast enhancement, structural similarity, and segmentation results on a Field II simulated image and actual B-mode cardiac ultrasound images captured in vivo. PMID:20227984

  13. Assessing Bolus Retention in Achalasia using High Resolution Manometry with Impedance: A Comparator Study with Timed Barium Esophagram

    PubMed Central

    Cho, Yu K.; Lipowska, Anna M.; Nicodème, Frédéric; Teitelbaum, Ezra N.; Hungness, Eric S.; Johnston, Elyse R.; Gawron, Andrew; Kahrilas, Peter J.; Pandolfino, John E.

    2014-01-01

    Background The aim of this study was to assess whether high-resolution impedance-manometry (HRIM) could be utilized to assess bolus retention similar to the timed barium esophagram (TBE). Method 20 achalasia patients [10 males, ages 21–79] were prospectively evaluated with HRIM and TBE to determine the correlation between barium column height and the impedance bolus height (IBH). The TBE protocol utilized a 200 ml barium challenge and the HRIM protocol utilized a 200 ml saline challenge protocol. Both protocols were performed in an upright position and the heights of the barium and impedance columns were measured at 1 and 5 minutes. Analysis of IBH was performed with a topographic technique and a spatial impedance variation plot. Results There was no significant difference between the median IBH and barium column at 1 minute [IBH 12.0 cm (IQR, 8.0–18.0), TBE 12.0 cm (IQR, 7.0–19.0), P=0.90] or 5 minutes [IBH 11.0 cm (IQR, 1.0–17.0), TBE 9.0 cm (IQR, 4.0–12.0), P=0.47]. Additionally, the correlation between the two measurements at 1 and 5 minutes was 0.60 and 0.86, respectively. Using a barium column or impedance height of >5.0 as a definition of bolus retention was associated with 75% concordance at 1 minute and 95% concordance at 5 minutes. Conclusion There was excellent agreement between TBE and HRIM for assessing bolus retention at 5 minutes. Thus, HRM with impedance may be utilized as a single test to assess bolus retention and motor function in the management of achalasia. PMID:24710506

  14. Quantitative analysis of contrast to noise ratio using a phase contrast x-ray imaging prototype

    NASA Astrophysics Data System (ADS)

    Ghani, Muhammad U.; Wu, Di; Li, Yuhua; Kang, Minhua; Chen, Wei R.; Wu, Xizeng; Liu, Hong

    2013-02-01

    The purpose of this study was to determine the Contrast to Noise Ratio (CNR) of the x-ray images taken with the phase contrast imaging mode and compare them with the CNR of the images taken under the conventional mode. For each mode, three images were taken under three exposure conditions of 100 kVp (2.8mAs), 120 kVp (1.9mAs) and 140kVp (1.42mAs). A 1.61cm thick contrast detail phantom was used as an imaging object. For phase contrast, the source to image detector distance (SID) was 182.88 cm and the source to object (SOD) distance was 73.15 cm. The SOD was the same as SID in the conventional imaging mode. A computed radiography (CR) plate was used as a detector and the output CR images were converted to linear form in relation with the incident x-ray exposure. To calculate CNR, an image processing software was used to determine the mean pixel value and the standard deviation of the pixels in the region of interest (ROI) and in the nearby background around ROI. At any given exposure condition investigated in this study, the CNR values for the phase contrast images were better as compared to the corresponding conventional mode images. The superior image quality in terms of CNR is contributed by the phase-shifts resulted contrast, as well as the reduced scatters due to the air gap between the object and the detector.

  15. Small intestine contrast injection (image)

    MedlinePlus

    ... and throat, through the stomach into the small intestine. When in place, contrast dye is introduced and ... means of demonstrating whether or not the small intestine is normal when abnormality is suspected.

  16. [Allergy to radiographic contrast media].

    PubMed

    Vionnet, Julien; Petitpierre, Stéphanie; Fumeaux, Alexandre; Meuli, Reto; Spertini, Francois; Comte, Denis

    2013-04-17

    Allergy to radiographic contrast media Hypersensitivity reactions to radio-contrast media are common in the daily practice. These products are responsible for immediate (< or = 1 hour after administration) and non immediate (> 1 hour after administration) hypersensitivity reactions. A diagnostic work-up by an allergologist with skin tests and in some cases provocation tests is of value in reducing the risk of recurrent hypersensitivity reactions to iodinated contrast media. A careful selection of the patients is required because the incidence of breakthrough reactions is still concerning, even with proper premedication. Practical recommendations are presented in this article. For gadolinium-based contrast agents, data in the literature is not sufficient for suggesting guidelines. PMID:23667970

  17. Environmentally responsive MRI contrast agents

    PubMed Central

    Davies, Gemma-Louise; Kramberger, Iris; Davis, Jason J.

    2015-01-01

    Biomedical imaging techniques can provide a vast amount of anatomical information, enabling diagnosis and the monitoring of disease and treatment profile. MRI uniquely offers convenient, non-invasive, high resolution tomographic imaging. A considerable amount of effort has been invested, across several decades, in the design of non toxic paramagnetic contrast agents capable of enhancing positive MRI signal contrast. Recently, focus has shifted towards the development of agents capable of specifically reporting on their local biochemical environment, where a switch in image contrast is triggered by a specific stimulus/biochemical variable. Such an ability would not only strengthen diagnosis but also provide unique disease-specific biochemical insight. This feature article focuses on recent progress in the development of MRI contrast switching with molecular, macromolecular and nanoparticle-based agents. PMID:24040650

  18. Contrast-controlled retinal response

    NASA Astrophysics Data System (ADS)

    Sharma, Nachieketa K.

    2015-06-01

    A beam of light stimulates the retina weakly when its entry to the pupil is gradually shifted from the centre toward the edge. For single pupil entrance point the light, irrespective of its coherence would still show the Stiles-Crawford effect with diminished visibility toward the edge of the pupil. Only when coherent light is incident from opposing points in the pupil can the effect be cancelled. This paper has attempted a theoretical computation of how the contrast in an interference pattern formed on the retina controls the retina's response in three ways; first, by completely disregarding the Stiles Crawford diminution of effective brightness for unit contrast; next, taking the traditional SCE route for zero contrast, and finally enhancing the diminution in the effective brightness by giving an opposing boost to the visibility in commensurate with a contrast intermediate between the two extremes of unity and zero.

  19. Formulation procedure and spectral data for a coatings system optimally employing the high intrinsic reflectance of barium sulphate

    NASA Technical Reports Server (NTRS)

    Schutt, J. B.; Stromberg, E.; Shai, C. M.; Arens, J. F.

    1972-01-01

    The use of polyvinyl alcohol as a binder for barium sulphate does not allow the intrinsically high reflectance of this material in the near vacuum ultraviolet to be optimally employed. In an effort to better utilize this property, completely inorganic coatings systems are described, where from the intrinsically high reflectance of barium sulphate in this spectral region can be gotten. Potassium sulphate turns out to be the preferred binder. Compositions, formulating procedures, and application techniques are included. For completeness, absolute and relative reflectance data are included for intra- and intersystem comparisons.

  20. Microwave absorption properties of conducting polymer composite with barium ferrite nanoparticles in 12.4-18 GHz

    NASA Astrophysics Data System (ADS)

    Ohlan, Anil; Singh, Kuldeep; Chandra, Amita; Dhawan, S. K.

    2008-08-01

    Conducting polymer nanocomposites of polyphenyl amine with barium ferrite nanoparticles (50-70nm) have been synthesized via emulsion polymerization. The complex permittivity, permeability, and microwave absorption properties of the composite were studied in the 12.4-18GHz (Ku band) frequency range. The composite has shown high shielding effectiveness due to absorption (SEA) of 28.9dB (˜99.9%), which strongly depends on dielectric loss, magnetic permeability, and volume fraction of barium ferrite nanoparticles. The high value of SEA suggests that these composites can be used as a promising radar absorbing materials.