• Title, Summary, Keyword: barium

Search Result 769, Processing Time 0.036 seconds

Catalytic Effects of Barium Carbonate on the Anodic Performance of Solid Oxide Fuel Cells

  • Yoon, Sung-Eun;Ahn, Jae-Yeong;Park, Jong-Sung
    • Journal of the Korean Ceramic Society
    • /
    • v.52 no.5
    • /
    • pp.350-355
    • /
    • 2015
  • To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.

Influence on PET Exam Caused by Density Differences of Barium-sulfate Contrast Media (Barium 조영제의 농도 차이가 PET 검사에 미치는 영향)

  • Choi, Woo-Joon;Shin, Sang-Ki;Nam, Ki-Pyo;Park, Soon-Ki
    • The Korean Journal of Nuclear Medicine Technology
    • /
    • v.12 no.1
    • /
    • pp.27-32
    • /
    • 2008
  • Purpose: The evaluation of SUV (Standardized Uptake Values) for quantitative analysis in PET exam is the most significant. In PET exam, we make attenuation correction images by using $^{68}Ge$, $^{137}Cs$ or CT data. At this time, a distorted attenuation map affects quantitative analysis. After the exam using barium-sulfate and high density of barium contrast make attenuation map distorted. And then it brings bed influences on SUV. The aim of this study is to verify the relationship between high density barium-sulfate and SUV in PET exam. Materials and Methods By using $^{18}F$-FDG, we made barium-sulfate powder, density of 0, 1.5, 3, 5, 10 and 15% respectively and acquired PET and PET/CT images per each density. And we examined SUV variations from PET and PET/CT images according to differences of barium's density. Moreover, we finally calculated SUV causing variations in HU (Hounsfield Units) values to justify whether the differences of barium density bring any changes in PET/CT exam. Results: From PET images acquired from transmission scan with $^{68}Ge$, we got SUV figures from 6.46 to 6.8 in barium density between 0 to 15 percent. On the other hand, In PET images acquired from Tx scan that using CT, SUV was 6.77 to 23.73, derived from the same barium density. And CT HU values range from 29 to 2004. Conclusion: PET images from Tx data using $^{68}Ge$ weren't affected by barium density and had no differences in SUV. But in the PET/CT images using CT Tx data, there's considerable variations in HU and SUV values according to a difference of barium density in HU values. To perform a precise examination, barium sulfate should be removed from a human body before performing a PET exam.

  • PDF

Effect of Supporting Anions on Particle Characteristics of Barium Titanyl Oxalate Formed by Homogeneous Precipitation (지지 음이온이 균일 침전법에 의해 생성된 Barium Titanyl Oxalate의 입자특성에 미치는 영향)

  • Ryu, Kyoungyoul;Huh, Wooyoung;Lee, Chul
    • Analytical Science and Technology
    • /
    • v.11 no.4
    • /
    • pp.260-265
    • /
    • 1998
  • Spherical, ${\mu}m$-sized particles of barium titanyl oxalate were prepared by thermal decomposition of dimethyl oxalate in acidic barium and titanium solutions. Precipitation was carried out in the presence of several supporting anions. Spherical particles having a specific type of particle size distribution. i.e., unimodal or bimodal distribution, with mean size in the range of $0.2{\sim}3{\mu}m$, were formed depending on the supporting anions, oxalate ion generation rate and aging time. Particles of barium titanyl oxalate settled on the bottom of the beaker at the aging time of 120 min grew to the critical monosize of about $1.5{\sim}3{\mu}m$. XRD spectra and chemical analyses of barium titanate showed that barium titanyl oxalate with high qualities could be synthesized by choosing chloride ion as a supporting anion and increasing the reaction temperatures.

  • PDF

The Effect of Barium Sulfate on the Structural Transformations in Tricalcium Silicate (3CaO.$SiO_2$의 구조전이에 미치는 $BaSO_4$의 영향)

  • 서일영;최상흘
    • Journal of the Korean Ceramic Society
    • /
    • v.11 no.2
    • /
    • pp.17-21
    • /
    • 1974
  • Miscibility of barium sulfate in tricalcium silicate was investigated by firing 3CaCO3·SiO2 mixture containing barium sulfate at 1530℃. Added amount of barium sulfate to the mixture was zero to 5 mole % with intervals of 1 mole %. Lattice parametres were also calculated. Results were as follow; 1) Dissolution of barium sulfate in tricalcium silicate does not alter the symmetry in room temperature, but influences it's polymorphic transition forms, temperatures and thermal effects; modification triclinic Ⅱ is stabilized in room temperature. 2) Barium sulfate dissolves about up to 2 mole % in tricalcium silicate and more than this amount, tricalcium silicate formation is inhibited. 3) Unit cell volume of tricalcium silicate is slightly decreased with dissolution of barium sulfate, mainly because of contraction in c axis.

  • PDF

Preparation and Magnetic Properties of Ba-Ferrite Particles Using the Supercritical Water Crystallization Method

  • Nam, Sung-Chan;Kim, Kun-Joong;Park, Sang-Do
    • Proceedings of the Korean Magnestics Society Conference
    • /
    • /
    • pp.433-440
    • /
    • 2000
  • Barium ferrite particles were synthesized from Ba(NO$_3$)$_2$, Fe(NO$_3$)$_3$ and KOH mixed solutions using hydrothermal crystallization in supercritical water. The experimental apparatus for production of barium ferrite is a flow-type apparatus. Fine barium ferrite particles were produced because supercritical water causes the metal hydroxides to be rapidly dehydrated before significant growth takes place. The effects of Fe/Ba ratio and reaction time on the formation, particle size, and magnetic properties of barium ferrite were studied. When Fe/Ba ratio were varied from 0.5 to 12, single-phase barium ferrite powder was only produced in the range of 0.5〈Fe/Ba〈2. Also, with elevating reaction time, the BaO.6Fe$_2$O$_3$ particle size grew smaller. Especially, uniform barium hexaferrite particles of size 100-200nm were obtained at 80sec. In this study, therefore, single-phase barium ferrite particles are highly stable and can be produced continuously in a reaction time of less then 2min.

  • PDF

Synthesis of barium hexaaluminate by sol - gel method (졸 - 겔법에 의한 바륨헥사알루미네이트 합성)

  • 백영순;김형진
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.5 no.2
    • /
    • pp.142-151
    • /
    • 1995
  • Complex alkoxides were synthesized using metal alkoxide method and were then hydrolyzed to prepare the precursors using sol - gel method. Then, the precursors were calcined in order to make barium hexaaluminate. Factors affecting the material properties of the barium hexaaluminate precursors were studied and they are the kinds and amount of alcohols, and reaction time. In addition, in the course of hydrolysis, the effects of the amount of water, reaction temperature and aging time were also studied in terms of the specific surface area and average particle size of the barium hexaaluminates.

  • PDF

Modified Upper Gastrointestinal Study Using Methylcellulose After Administration of Barium Suspension : Comparison with Conventional Series (바륨 현탁액과 메틸셀룰로스(Methylcellulose)를 사용한 변형 상부위장관조영술 :전통적 바륨조영술과의 비교)

  • 이기창;최민철;서민호;정주현;윤정희
    • Journal of Veterinary Clinics
    • /
    • v.17 no.2
    • /
    • pp.411-415
    • /
    • 2000
  • For comparison with conventional barium-gastrointestinal study, modified method using barium and methylcellulose was performed in 16 normal dogs (4-8 kg) divided into two groups. The group 1 received 8ml/kg of 40% w/v barium suspension only, and group 2 had taken 15 ml/kg of 0.6% w/v methylcellulose after administration 4 ml/kg of 40% w/v barium suspension by feeding tube. The barium suspension was prepared mixing full strength-barium suspension with water and methylcellulose solution was produced by blending methylcellulose sterilized water Sequential radiographs, lateral and ventrodorsal projections were obtained at 5 minute, 20 minute,40 minute. 60 minute and every 30 minutes thereafter, until the contrast is seen in the large intestine Inage qual- ity was rated by three veterinary radiologists as " poor" " fair ". "good", or "excellent" We analyzed the relationship between image quality,, transit time. Between two techniques, the modified method with 4ml of 40% w/v barium suspension and 15 ml of 0.6% w/v methylcellulose showed much better image quality ["excellent" result in 7 of the 8 subjects (88%)] and shorter transit time (107 minutes) toe the cecum. In addition, the best image quality was obtained at 20 and 40 minutes after admin-istration of contrast agent. It call be concluded the modified gastrointestinal study using methylcel-lulose after administration of barium suspension was a simple technique and easily improved the image quality and diagnostic accuracy of gstrointestinal disorders in small animal.racy of gstrointestinal disorders in small animal.

  • PDF

Massive barium sulfate aspiration during upper gastrointestinal contrast material study in an elderly patient with dysphagia

  • Yun, Hae Ryong;Kim, Chang-gon;Park, Jihye;Park, Yong eun;lee, Yong-il;Yoo, Byung-Woo;Chung, Kyung Soo;Kim, Young Sam;Song, Joo Han
    • Yeungnam University Journal of Medicine
    • /
    • v.33 no.2
    • /
    • pp.162-165
    • /
    • 2016
  • Barium sulfate is an inert material used as a radiographic contrast medium during upper gastrointestinal contrast studies for evaluation of patients with dysphagia. Oral barium aspiration is an uncommon but well-reported complication of this procedure. While barium aspiration of small amounts may not cause any symptoms, massive barium aspiration can be life-threatening, particularly in elderly patients with multiple comorbidities. In this case report, we describe an elderly patient with multiple comorbidities who presented with thyrotoxicosis and dysphagia, and then died after massive barium aspiration. Despite administration of intensive medical care with ventilator support and therapeutic bronchoalveolar lavage to remove the aspirated barium, the patient died of multiple organ failure 9 days after barium aspiration. Clinicians should pay attention to elderly patients with predisposing factors for aspiration in whom upper gastrointestinal barium contrast studies are indicated, and should consider other diagnostic tools for evaluation of dysphagia in this population.

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

  • Roh, Simon;Iannettoni, Mark D.;Keech, John C.;Bashir, Mohammad;Gruber, Peter J.;Parekh, Kalpaj R.
    • The Korean Journal of Thoracic and Cardiovascular Surgery
    • /
    • v.49 no.2
    • /
    • pp.99-106
    • /
    • 2016
  • 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.

Powder synthesis and morphology changes of strontium barium niobate by molten salt method (용융염법에 의한 strontium barium niobate 분말 합성 및 분말의 형상 변화)

  • 윤상옥;박상엽
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.6 no.4
    • /
    • pp.501-508
    • /
    • 1996
  • Strontium barium niobate powders were prepared by NaCl-KCl molten salt, and reaction process and morphology change of strontium barium niobate were investigated as a function of reaction temperature, time, and amount of molten salt. With increasing the reaction temperature and time, the reacted fraction was increased and the morphology of powder was changed from lumpy shape into meedle-like shape. With increasing the amount of molten salt, reacted fraction was increased rapidly, but the morphology of powder was changed from needle-like shape into spherical shape. Strontium barium niobate powder, over 90 % in fraction reacted, was obtained from the reaction conditions at $1000^{\circ}C$ for small flux ratio (=1) and at $650^{\circ}C$ for large flux ratio (=4).

  • PDF