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Sample records for bismuth shields results

  1. Evaluation of the usefulness of bismuth shields in PET/CT examination

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    Park, Hoon Hee; Lyu, Kwang Yeul [Dept. of Radiological Technology, Shingu College, Sungnam (Korea, Republic of); Lee, Ju Young [Graduate School of Public Health, Yonsei Universtiy, Seoul (Korea, Republic of); Kim, Ji Hyeon [Dept. of Nuclear Medicine, Seoul Medical Center, Seoul (Korea, Republic of); Kung, Sik Nam [Dept. of Nuclear Medicine, Konkuk Univeristy Medical Center, Seoul (Korea, Republic of); Lee, Tae Soo [Dept. of Biomedical Enginnering, Chugnbuk National University, Junju (Korea, Republic of)

    2014-03-15

    Recently with CT developed, various studies for reduction of exposure dose is underway. Study of bismuth shields in these studies is actively underway, and has already been applied in the clinical. However, the application of the PET/CT examination was not activated. Therefore, through this study, depending on the application of bismuth shields in the PET/CT examination, we identify the quality of the image and the impact on the Standard Uptake Value (SUV). In this study, to apply to the shielding of the breast, by using the bismuth shields that contains 0.06 mm Pb ingredients, was applied to the PET/CT GEMINI TF 64 (Philips Healthcare, Cleveland, USA). Phantom experiments using the NEMA IEC Body Phantom, images were acquired according to the presence or absence of bismuth shields apply. Also, When applying, images were obtained by varying the spacing 0, 1, 2 cm each image set to the interest range in the depth of the phantom by using EBW-NM ver.1.0. When image of the PET Emission acquires, the SUV was in increased depending on the use of bismuth shields, difference in the depth to the surface from deep in the phantom increasingly SUV increased (P<0.005). Also, when using shields, as the more gab decreased, SUV is more increased (P<0.005). Through this study, PET/CT examination by using of bismuth shields which is used as purpose of reduction dose. When using shields, the difference of SUV resulting from the application of bismuth shields exist and that difference when gab is decrease and surface is wider. Therefore, setting spacing of shield should be considered, if considering the reduction of the variation of SUV and image quality, disease of deep organs should be a priority rather than superficial organ disease. Use of bismuth shielding factor considering the standard clinical examination, decrease unnecessary exposure can be expected to be considered.

  2. Radioprotection to the Gonads in Pediatric Pelvic Radiography: Effectiveness of Developed Bismuth Shield

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    Vahid Karami

    2017-06-01

    Full Text Available Background: The use and effectiveness of traditional lead gonad shields in pediatric pelvic radiography has been challenged by several literatures over the past two decades. The aim of this study was to develop a new radioprotective gonad shields to be use in pediatric pelvic radiography. Materials and Methods: The commercially available 0.06 mm lead equivalent bismuth garment has cropped squarely and used as ovarian shield to cover the entire region of pelvis. In order to prevent deterioration of image quality due to beam hardening artifacts, a 1-cm foam as spacer was located between the shield and patients pelvis. Moreover, we added a lead piece at the cranial position of the bismuth garment to absorb the scatter radiations to the radiosensitive organs. In girls, 49 radiographs with shield and 46 radiographs without shield was taken. The radiation dose was measured using thermoluminescent dosimeters (TLDs. Image quality assessments were performed using the European guidelines. For boys, the lead testicular shields was developed using 2 cm bismuth garment, added to the sides. The prevalence and efficacy of testicular shields was assessed in clinical practice fromFebruary 2016 to June 2016. Results: Without increasing the dose to the breast, thyroid and the lens of the eyes, the use of bismuth shield has reduced the entrance skin dose(ESD of the pelvis and radiation dose to the ovaries by 62.2% and 61.7%, respectively (P

  3. Dose reduction in CT using bismuth shielding: measurements and Monte Carlo simulations.

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    Chang, Kyung-Hwan; Lee, Wonho; Choo, Dong-Myung; Lee, Choon-Sik; Kim, Youhyun

    2010-03-01

    In this research, using direct measurements and Monte Carlo calculations, the potential dose reduction achieved by bismuth shielding in computed tomography was evaluated. The patient dose was measured using an ionisation chamber in a polymethylmethacrylate (PMMA) phantom that had five measurement points at the centre and periphery. Simulations were performed using the MCNPX code. For both the bare and the bismuth-shielded phantom, the differences of dose values between experiment and simulation were within 9%. The dose reductions due to the bismuth shielding were 1.2-55% depending on the measurement points, X-ray tube voltage and the type of shielding. The amount of dose reduction was significant for the positions covered by the bismuth shielding (34 - 46% for head and 41 - 55% for body phantom on average) and negligible for other peripheral positions. The artefact on the reconstructed images were minimal when the distance between the shielding and the organs was >1 cm, and hence the shielding should be selectively located to protect critical organs such as the eye lens, thyroid and breast. The simulation results using the PMMA phantom was compared with those using a realistically voxelised phantom (KTMAN-2). For eye and breast, the simulation results using the PMMA and KTMAN-2 phantoms were similar with each other, while for thyroid the simulation results were different due to the discrepancy of locations and the sizes of the phantoms. The dose reductions achieved by bismuth and lead shielding were compared with each other and the results showed that the difference of the dose reductions achieved by the two materials was less than 2-3%.

  4. Gamma-ray shielding and structural properties of barium-bismuth-borosilicate glasses

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    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.

  5. Gamma ray shielding study of barium-bismuth-borosilicate glasses as transparent shielding materials using MCNP-4C code, XCOM program, and available experimental data

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    Bagheri, Reza; Yousefinia, Hassan [Nuclear Fuel Cycle Research School (NFCRS), Nuclear Science and Technology Research Institute (NSTRI), Atomic Energy Organization of Iran, Tehran (Iran, Islamic Republic of); Moghaddam, Alireza Khorrami [Radiology Department, Paramedical Faculty, Mazandaran University of Medical Sciences, Sari (Iran, Islamic Republic of)

    2017-02-15

    In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and 10th value layer values of barium-bismuth-borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium-bismuth-borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

  6. Corneal Dose Reduction Using a Bismuth-Coated Latex Shield over the Eyes During Brain SPECT/CT.

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    Matsutomo, Norikazu; Fukunaga, Masaaki; Onishi, Hideo; Yamamoto, Tomoaki

    2017-09-01

    This study aimed to determine whether a bismuth-coated latex shield (B-shield) could protect the eyes during brain SPECT/CT. Methods: A shield containing the heavy metal bismuth (equivalent to a 0.15-mm-thick lead shield) was placed over a cylindric phantom and the eyes of a 3-dimensional brain phantom filled with (99m)Tc solution. Subsequently, phantoms with and without the B-shield were compared using SPECT/CT. The CT parameters were 30-200 mA and 130 kV. The dose reduction achieved by the B-shield was measured using a pencil-shaped ionization chamber. The protective effects of the B-shield were determined by evaluating relative radioactivity concentration as well as artifacts (changes in CT number), linear attenuation coefficients, and coefficients of variation on SPECT images. Results: The radiation doses with and without the B-shield were 0.14-0.77 and 0.36-1.93 mGy, respectively, and the B-shield decreased the average radiation dose by about 60%. The B-shield also increased the mean CT number, but only at locations just beneath the surface of the phantom. Streaks of higher density near the underside of the B-shield indicated beam hardening. Linear attenuation coefficients and the coefficients of variation did not significantly differ between phantoms with and without the B-shield, and the relative (99m)Tc radioactivity concentrations were not affected. Conclusion: The B-shield decreased the radiation dose without affecting estimated attenuation correction or radioactivity concentrations. Although surface artifacts increased with the B-shield, the quality of the SPECT images was acceptable. B-shields can help protect pediatric patients and patients with eye diseases who undergo SPECT imaging. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

  7. Study of some health physics parameters of bismuth-ground granulated blast furnace slag shielding concretes

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    Kumar, Sandeep; Singh, Sukhpal

    2016-05-01

    The Bismuth-ground granulated blastfurnace slang (Bi-GGBFS) concrete samples were prepared. The weight percentage of different elements present inBi-GGBFS Shielding concretewas evaluated by Energy Dispersive X-ray Microanalysis (EDX). The exposure rate and absorbed dose rate characteristics were calculated theoretically for radioactive sources namely 241Am and 137Cs. Our calculations reveal that the Bi-GGBFS concretes are effective in shielding material for gamma radiations.

  8. Evaluation of bismuth shielding effectiveness in reducing breast absorbed dose during thoracic CT scan

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    Alonso, T. C.; Mourao, A. P.; Santana, P. C.; Silva, T. A. [Federal University of Minas Gerais, Program of Nuclear Science and Techniques, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

    2015-10-15

    Computed Tomography (CT) is an essential method for tracking neoplasia and efficiently diagnosing a wide variety of thoracic diseases. CT is generally considered the most accurate choice for lung examination. Due to the growing use of CT, breast and other superficial and radiosensitive organs are unnecessarily irradiated during radiological procedures, thus requiring the development of strategies appropriate to optimize and, if possible, to reduce the radiation dose. The use of bismuth shielding to reduce radiation dose absorbed by breast during thoracic CT examinations has been the subject of many studies recently published by Brazilian and foreign authors of various fields. The purpose of this paper is both to accurately determine the glandular dose when breast is exposed to radiation and to assess the reduction in absorbed dose during thoracic CT examinations, using a set of Thermoluminescent Dosimeters, an anthropomorphic phantom and bismuth shielding. (Author)

  9. Lead versus bismuth-antimony shield for fetal dose reduction at different gestational ages at CT pulmonary angiography.

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    Chatterson, Leslie C; Leswick, David A; Fladeland, Derek A; Hunt, Megan M; Webster, Stephen T

    2011-08-01

    To compare the effective fetal dose reduction at different stages of gestation during maternal computed tomographic (CT) pulmonary angiography by using traditional lead apron and bismuth-antimony shields combined with limited z-axis and tube current. Phantom with gravid prosthesis, 0.5-mm lead, and two grades of bismuth-antimony shield was used. Thermoluminescent dosimeters (TLDs) measured radiation in the first- to third-trimester uterus. Fetal dose was determined for each gestation by using 100 kVp to the costophrenic angles (CPAs) with and without shielding for a total of 12 scans. Eight third-trimester scans were used to compare shields using 120 kVp to CPAs versus those using 100 kVp to the diaphragm. Average fetal dose increased with gestation with use of 100 kVp to CPAs, from 0.11 mGy in first trimester to 0.50 mGy in third trimester. Average third-trimester unshielded fetal dose was reduced from 0.82 mGy by using 120 kVp to CPAs to 0.17 mGy (79%, P Lead apron reduced dose more than either of the bismuth-antimony shields (72%-79% vs 57%-81%) with use of 100 kVp to CPAs. Shields reduced the dose by 73% (lead), 62% (90% attenuation bismuth-antimony), and 72% (95% attenuation bismuth-antimony) (P shields was demonstrated with 100 kVp to the diaphragm (P shields at reducing fetal dose. Shielding improves reduction with no significant difference between lead and bismuth-antimony shields when conservative scanning parameters are observed. © RSNA, 2011.

  10. Evaluation of Radiation Dose Reduction during CT Scans Using Oxide Bismuth and Nano-Barium Sulfate Shields

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    Seoung, Youl-Hun

    2015-01-01

    The purpose of the present study was to evaluate radiation dose reduction and image quality during CT scanning by using a new dose reduction fiber sheet (DRFS) with commercially available bismuth shields. These DRFS were composed of nano-barium sulfate (BaSO4), filling the gaps left by the large oxide bismuth (Bi2O3) particle sizes. The radiation dose was measured five times at directionss of 12 o'clock from the center of the polymethyl methacrylate (PMMA) head phantom to calculate an average value using a CT ionization chamber. The image quality measured CT transverse images of the PMMA head phantom depending on X-ray tube voltages and the type of shielding. Two regions of interest in CT transverse images were chosen from the right and left areas under the surface of the PMMA head phantom and from ion chamber holes located at directions of 12 o'clock from the center of the PMMA head phantom. The results of this study showed that the new DRFS shields could reduce dosages to 15.61%, 23.05%, and 22.71% more in ...

  11. Investigation of gamma ray shielding efficiency and mechanical performances of concrete shields containing bismuth oxide as an environmentally friendly additive

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    Yao, Ya; Zhang, Xiaowen; Li, Mi; Yang, Rong; Jiang, Tianjiao; Lv, Junwen

    2016-10-01

    Concrete has a proven ability to attenuate gamma rays and neutrons without compromising structural property; therefore, it is widely used as the primary shielding material in many nuclear facilities. Recently, there is a tendency toward using various additives to enhance the shielding properties of these concrete mixtures. However, most of these additives being used either pose hygiene hazards or require special handling processes. It would be ideal if environmentally friendly additives were available for use. The bismuth oxide (Bi2O3) additive shows promise in various shielding applications due to its proven radiation attenuation ability and environmentally friendly nature. To the best of our knowledge, however, Bi2O3 has never been used in concrete mixtures. Therefore, for this research, we fabricated the Bi2O3-based concrete mixtures by adding Bi2O3 powder in the ordinary concrete mixture. Concrete mixtures with lead oxide (PbO) additives were used for comparison. Radiation shielding parameters like the linear attenuation coefficients (LAC) of all these concrete mixtures showing the effects of the Bi2O3 additions are presented. The mechanical performances of concrete mixtures incorporated with Bi2O3 additive were also investigated. It suggested that the concrete mixture containing 25% Bi2O3 powder (B5 in this study) provided the best shielding capacity and mechanical performance among other mixes. It has a significant potential for application as a structural concrete where radiological protection capability is required.

  12. Comparative study of radiation shielding parameters for bismuth borate glasses

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    Kaundal, Rajinder Singh, E-mail: rajinder_apd@yahoo.com [Department of Physics, School of Physical Sciences, Lovely Professional University, Phagwara, Punjab (India)

    2016-07-15

    Melt and quench technique was used for the preparation of glassy samples of the composition x Bi{sub 2}O{sub 3-}(1-x) B{sub 2}O{sub 3} where x= .05 to .040. XCOM computer program is used for the evaluation of gamma-ray shielding parameters of the prepared glass samples. Further the values of mass attenuation coefficients, effective atomic number and half value layer for the glassy samples have been calculated in the energy range from 1KeV to 100GeV. Rigidity of the glass samples have been analyzed by molar volume of the prepared glass samples. (author)

  13. Evaluation of gamma-ray exposure buildup factors and neutron shielding for bismuth borosilicate glasses

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    Singh, Vishwanath P.; Badiger, N. M.; Chanthima, N.; Kaewkhao, J.

    2014-05-01

    Gamma-ray exposure buildup factor (EBF) values and neutron shielding effectiveness of bismuth borosilicate (BBS) glass systems in composition (50-x)SiO2:15B2O3:2Al2O3:10CaO:23Na2O:xBi2O3 (where x=0, 5, 10, 15 and 20 mol%) were calculated. The EBF values were computed for photon energy 0.015-15 MeV up to penetration depths of 40 mfp (mean free path) by the geometrical progression (G-P) method. The EBF values were found dependent upon incident photon energy, penetration and bismuth molar concentration. In low- and high-energy photon regions, the EBF values were minimum whereas maximum in the intermediate-energy region. The fast neutron removal cross sections for energy 2-12 MeV were calculated by the partial density method. The BBS glass with 20 mol% Bi2O3 is found to be superior gamma-ray and neutron transparent shielding. The EBF values of the BBS glasses were compared with steel-magnetite concrete and lead. The investigation was carried out to explore the advantages of the BBS glasses in different radiation shielding applications.

  14. Bismuth Infusion of ABS Enables Additive Manufacturing of Complex Radiological Phantoms and Shielding Equipment

    Directory of Open Access Journals (Sweden)

    Justin Ceh

    2017-02-01

    Full Text Available Radiopacity is a critical property of materials that are used for a range of radiological applications, including the development of phantom devices that emulate the radiodensity of native tissues and the production of protective equipment for personnel handling radioactive materials. Three-dimensional (3D printing is a fabrication platform that is well suited to creating complex anatomical replicas or custom labware to accomplish these radiological purposes. We created and tested multiple ABS (Acrylonitrile butadiene styrene filaments infused with varied concentrations of bismuth (1.2–2.7 g/cm3, a radiopaque metal that is compatible with plastic infusion, to address the poor gamma radiation attenuation of many mainstream 3D printing materials. X-ray computed tomography (CT experiments of these filaments indicated that a density of 1.2 g/cm3 of bismuth-infused ABS emulates bone radiopacity during X-ray CT imaging on preclinical and clinical scanners. ABS-bismuth filaments along with ABS were 3D printed to create an embedded human nasocranial anatomical phantom that mimicked radiological properties of native bone and soft tissue. Increasing the bismuth content in the filaments to 2.7 g/cm3 created a stable material that could attenuate 50% of 99mTechnetium gamma emission when printed with a 2.0 mm wall thickness. A shielded test tube rack was printed to attenuate source radiation as a protective measure for lab personnel. We demonstrated the utility of novel filaments to serve multiple radiological purposes, including the creation of anthropomorphic phantoms and safety labware, by tuning the level of radiation attenuation through material customization.

  15. Bismuth Infusion of ABS Enables Additive Manufacturing of Complex Radiological Phantoms and Shielding Equipment.

    Science.gov (United States)

    Ceh, Justin; Youd, Tom; Mastrovich, Zach; Peterson, Cody; Khan, Sarah; Sasser, Todd A; Sander, Ian M; Doney, Justin; Turner, Clark; Leevy, W Matthew

    2017-02-24

    Radiopacity is a critical property of materials that are used for a range of radiological applications, including the development of phantom devices that emulate the radiodensity of native tissues and the production of protective equipment for personnel handling radioactive materials. Three-dimensional (3D) printing is a fabrication platform that is well suited to creating complex anatomical replicas or custom labware to accomplish these radiological purposes. We created and tested multiple ABS (Acrylonitrile butadiene styrene) filaments infused with varied concentrations of bismuth (1.2-2.7 g/cm³), a radiopaque metal that is compatible with plastic infusion, to address the poor gamma radiation attenuation of many mainstream 3D printing materials. X-ray computed tomography (CT) experiments of these filaments indicated that a density of 1.2 g/cm³ of bismuth-infused ABS emulates bone radiopacity during X-ray CT imaging on preclinical and clinical scanners. ABS-bismuth filaments along with ABS were 3D printed to create an embedded human nasocranial anatomical phantom that mimicked radiological properties of native bone and soft tissue. Increasing the bismuth content in the filaments to 2.7 g/cm³ created a stable material that could attenuate 50% of (99m)Technetium gamma emission when printed with a 2.0 mm wall thickness. A shielded test tube rack was printed to attenuate source radiation as a protective measure for lab personnel. We demonstrated the utility of novel filaments to serve multiple radiological purposes, including the creation of anthropomorphic phantoms and safety labware, by tuning the level of radiation attenuation through material customization.

  16. Bismuth Infusion of ABS Enables Additive Manufacturing of Complex Radiological Phantoms and Shielding Equipment

    Science.gov (United States)

    Ceh, Justin; Youd, Tom; Mastrovich, Zach; Peterson, Cody; Khan, Sarah; Sasser, Todd A.; Sander, Ian M.; Doney, Justin; Turner, Clark; Leevy, W. Matthew

    2017-01-01

    Radiopacity is a critical property of materials that are used for a range of radiological applications, including the development of phantom devices that emulate the radiodensity of native tissues and the production of protective equipment for personnel handling radioactive materials. Three-dimensional (3D) printing is a fabrication platform that is well suited to creating complex anatomical replicas or custom labware to accomplish these radiological purposes. We created and tested multiple ABS (Acrylonitrile butadiene styrene) filaments infused with varied concentrations of bismuth (1.2–2.7 g/cm3), a radiopaque metal that is compatible with plastic infusion, to address the poor gamma radiation attenuation of many mainstream 3D printing materials. X-ray computed tomography (CT) experiments of these filaments indicated that a density of 1.2 g/cm3 of bismuth-infused ABS emulates bone radiopacity during X-ray CT imaging on preclinical and clinical scanners. ABS-bismuth filaments along with ABS were 3D printed to create an embedded human nasocranial anatomical phantom that mimicked radiological properties of native bone and soft tissue. Increasing the bismuth content in the filaments to 2.7 g/cm3 created a stable material that could attenuate 50% of 99mTechnetium gamma emission when printed with a 2.0 mm wall thickness. A shielded test tube rack was printed to attenuate source radiation as a protective measure for lab personnel. We demonstrated the utility of novel filaments to serve multiple radiological purposes, including the creation of anthropomorphic phantoms and safety labware, by tuning the level of radiation attenuation through material customization. PMID:28245589

  17. Results of shielding characteristics tests in Monju

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    Usami, Shin; Suzuoki, Zenro; Deshimaru, Takehide; Nakashima, Fumiaki [Japan Nuclear Cycle Development Inst., Tsuruga, Fukui (Japan)

    2001-06-01

    In the prototype fast breeder reactor Monju, the shielding characteristics tests were made around the reactor core, the primary heat transport system, and the fuel handling and storage system as a part of the system start-up tests from 0% to 45% of rated power from October 1993 through December 1995. The results of the measurements, analyses and evaluations in these tests validated the FBR shielding analysis methods and demonstrated that there was a safe shielding design margin in Monju. The important basic data for use in future FBR shielding design were successfully acquired. In order to obtain more substantial basic data and to improve the accuracy of the analyses, the next shielding measurements are planned for the period of the system start-up tests at the restart of Monju. (author)

  18. Adaptive statistical iterative reconstruction and bismuth shielding for evaluation of dose reduction to the eye and image quality during head CT

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    Kim, Myeong Seong [The Korean National Cancer Center, Goyang (Korea, Republic of); Seoul National University, Seoul (Korea, Republic of); Choi, Ji Won [Jeonju University, Jeonju (Korea, Republic of); Kim, Sun Young [Hallym University of Graduate Studies, Seoul (Korea, Republic of); The Korean National Cancer Center, Goyang (Korea, Republic of); Kweon, Dae Cheol [Shinhan University, Uijeongbu (Korea, Republic of)

    2014-03-15

    There is a concern regarding the adverse effects of increasing radiation doses due to repeated computed tomography (CT) scans, especially in radiosensitive organs and portions thereof, such as the lenses of the eyes. Bismuth shielding with an adaptive statistical iterative reconstruction (ASIR) algorithm was recently introduced in our clinic as a method to reduce the absorbed radiation dose. This technique was applied to the lens of the eye during CT scans. The purpose of this study was to evaluate the reduction in the absorbed radiation dose and to determine the noise level when using bismuth shielding and the ASIR algorithm with the GE DC 750 HD 64-channel CT scanner for CT of the head of a humanoid phantom. With the use of bismuth shielding, the noise level was higher in the beam-hardening artifact areas than in the revealed artifact areas. However, with the use of ASIR, the noise level was lower than that with the use of bismuth alone; it was also lower in the artifact areas. The reduction in the radiation dose with the use of bismuth was greatest at the surface of the phantom to a limited depth. In conclusion, it is possible to reduce the radiation level and slightly decrease the bismuth-induced noise level by using a combination of ASIR as an algorithm process and bismuth as an in-plane hardware-type shielding method.

  19. Comparative study of lead borate and bismuth lead borate glass systems as gamma-radiation shielding materials

    Science.gov (United States)

    Singh, Narveer; Singh, Kanwar Jit; Singh, Kulwant; Singh, Harvinder

    2004-09-01

    Gamma-ray mass attenuation coefficients have been measured experimentally and calculated theoretically for PbO-B 2O 3 and Bi 2O 3-PbO-B 2O 3 glass systems using narrow beam transmission method. These values have been used to calculate half value layer (HVL) parameter. These parameters have also been calculated theoretically for some standard radiation shielding concretes at same energies. Effect of replacing lead by bismuth has been analyzed in terms of density, molar volume and mass attenuation coefficient.

  20. Radiation dose reduction to the critical organ with bismuth shielding during endovascular coil embolisation for cerebral aneurysms.

    Science.gov (United States)

    Han, Su Chul; Kwon, Soon Chan

    2013-09-01

    This study evaluated certified dose reduction with bismuth shielding during an endovascular coiling procedure for cerebral aneurysms using a thermoluminescent dosemeter-100 H. A total of 60 patients were enrolled in the study and randomised into two groups (shielding group and unshielded group). In the unshielded group, the total dose-area product was 286.46 Gy cm(2), the fluoroscopy time was 61.57 min and the procedure time was 96.57 min. In the shielding group, those values were 256.36 Gy cm(2), 51.10 min and 91.00 min, respectively. The reductions in the organ-equivalent doses in the right eye, left eye and thyroid were 32.9 % (11.43 mSv), 28.9 % (17.58 mSv) and 68.1 % (20.48 mSv), respectively. The reductions in the relative organ doses were 21.6, 20.8, and 64.4 %, respectively. Bi shielding was feasible and effective for dose reduction during this neurointerventional procedure.

  1. Technique and results of cartilage shield tympanoplasty

    Directory of Open Access Journals (Sweden)

    Sohil I Vadiya

    2014-01-01

    Full Text Available Aim: Use of cartilage for repair of tympanic membrane is recommended by many otologists. The current study aims at evaluating results of cartilage shield tympanoplasty in terms of graft take up and hearing outcomes. Material and Methods: In the current study, cartilage shield tympanoplasty(CST is used in ears with high risk perforations of the tympanic membrane. A total of 40 ears were selected where type I CST was done in 30 ears and type III CST was done in 10 ears. Results: An average of 37.08 dB air bone gap(ABG was present in pre operative time and an average of 19.15 dB of ABG was observed at 6 months after the surgery with hearing gain of 17.28 dB on average was observed. Graft take up rate of 97.5% was observed. The technique is modified to make it easier and to minimize chances of lateralization of graft. Conclusion: The hearing results of this technique are comparable to other methods of tympanic membrane repair.

  2. Evaluation in the use of bismuth shielding on cervical spine CT scan using a male phantom

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    Aleme, C.; Mourao, A. P. [Centro Federal de Educacion Tecnologica de Minas Gerais, Biomedical Engineering Center, Belo Horizonte - MG (Brazil); Lyra, M. A., E-mail: carolinaaleme@gmail.com [Universidad Federal de Minas Gerais, Department of Nuclear Engineering, Av. Pdte. Antonio Carlos 6627, Pampulha, 31270-91 Belo Horizonte - MG (Brazil)

    2014-08-15

    The cervical spine is the region of the column that articulates the head and chest. The tests of computed tomography (CT) performed in this region have as main objectives to diagnose fractures, dislocations and tumors. In CT scans the cervical spine volume is limited by the foramen Magnum and the first thoracic vertebra. In this region is the thyroid that is directly irradiated by X-ray beam during cervical scan. Based on this information, it was studied the dose variation deposited in thyroid and in nearby organs, such as: lenses, spinal cord in the foramen Magnum region and breasts, with and without the use of bismuth protector. In this study was used a male anthropomorphic phantom and thermoluminescent s dosimeters (TLD-100) were required to register the individual doses in the organs of interest. CT scans were performed on a GE Bright Speed scanner of 32 channels. With the data obtained, it was found the organ dose variation. The largest recorded dose was in the thyroid. Comparing two scans it was possible to note that the use of the bismuth protector promoted a 26% reduction in the thyroid dose and an increase in the lens dose. (Author)

  3. Evaluation of the efficiency of bismuth breast shield in CT chest paediatric examinations; Valoracion en el paciente pediatrico de la eficacia de los protectores de bien procedimientos de TC de torax con sistemas de control automatico de intensidad

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    Sevillano, D.; Espana, M. L.; Castro, P.; Minguez, C.; Albi, G.; Garcia, E.; Lopez Franco, P.

    2006-07-01

    The aim of this study is to evaluate the efficiency of bismuth breast shield in CT chest paediatric examinations when automatic exposure control techniques are used. The influence in the radiation dose and the image quality has been evaluated with and without the breast shield in the scoutview. In addition the radiation dose in shielded and non-shielded areas has been compared. Measurements were made in a 16 cm diameter cylindrical PMMA phantom simulating a newborn, and older children were simulated controlling the maximum intensities allowed by the automatic exposure control system AutomA. The highest dose reduction (59%) was obtained with AutomA system and when the breast shield is not used in the scoutview. This reduction in the radiation dose does not mean a significant increase of noise level. The use of the breast shield in the scoutview yielded an increase in the radiation dose in non-shielded areas. The use of bismuth breast shield is recommended only after the scoutview in order to optimise the radiation dose in CT chest paediatric examination when using automatic exposure control AutomA. (Author)

  4. [Breast dose reduction in female CT screening for lung cancer using various metallic shields].

    Science.gov (United States)

    Takada, Kenta; Kaneko, Junichi; Aoki, Kiyoshi

    2009-12-20

    We evaluated the effectiveness of metallic shields that were used for reduction of the breast dose in thoracic computed tomography(CT). For the evaluation, we measured breast surface dose and image standard deviation(SD)in the lung area. The metallic shields were made from bismuth, zinc, copper, and iron. The bismuth shield has been marketed and used for dose reduction. The other three metallic shields were chosen because they have lower atomic numbers and a lower yield of characteristic X-rays. As a result, use of the metallic shields showed a lower breast dose than the decrement of the tube current in the same image SD. The insertion of a thin aluminum sheet between the shield and a phantom was also effective in reducing breast surface dose. We calculated the dose reduction rate to evaluate the effectiveness of these metallic shields. This dose reduction rate was defined as the ratio of the decrease in breast surface dose by metallic shields to the breast surface dose measured with the tube current decrement in the same image SD. The maximum dose reduction rate was 6.4% for the bismuth shield, and 12.0-13.3% for the other shields. These results indicate that the shields made from zinc, copper, and iron are more effective for dose reduction than the shield made form bismuth. The best dose reduction rate, 13.3%, has been achieved when the zinc shield placed 20 mm apart from a phantom with 0.2 mm aluminum was used.

  5. Radiation fields from neutron generators shielded with different materials

    Science.gov (United States)

    Chichester, D. L.; Blackburn, B. W.

    2007-08-01

    As a general guide for assessing radiological conditions around a DT neutron generator numerical modeling has been performed to assess neutron and photon dose profiles for a variety of shield materials ranging from 1 to 100 cm thick. In agreement with accepted radiation safety practices high-Z materials such as bismuth and lead have been found to be ineffective biological shield materials, owing in part to the existence of (n,2n) reaction channels available with 14.1 MeV DT neutrons, while low-Z materials serve as effective shields for these sources. Composite materials such as a mixture of polyethylene and bismuth, or regular concrete, are ideal shield materials for neutron generator radiation because of their ability to attenuate internally generated photon radiation resulting from neutron scattering and capture within the shields themselves.

  6. Corrosion by liquid lead and lead-bismuth: experimental results review and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinsuo [Los Alamos National Laboratory

    2008-01-01

    Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews corrosion by liquid lead and lead bismuth, including the corrosion mechanisms, corrosion inhibitor and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviors of steels in liquid lead and lead-bismuth are predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead bismuth as heat transfer media.

  7. Early Results from the Advanced Radiation Protection Thick GCR Shielding Project

    Science.gov (United States)

    Norman, Ryan B.; Clowdsley, Martha; Slaba, Tony; Heilbronn, Lawrence; Zeitlin, Cary; Kenny, Sean; Crespo, Luis; Giesy, Daniel; Warner, James; McGirl, Natalie; hide

    2017-01-01

    The Advanced Radiation Protection Thick Galactic Cosmic Ray (GCR) Shielding Project leverages experimental and modeling approaches to validate a predicted minimum in the radiation exposure versus shielding depth curve. Preliminary results of space radiation models indicate that a minimum in the dose equivalent versus aluminum shielding thickness may exist in the 20-30 g/cm2 region. For greater shield thickness, dose equivalent increases due to secondary neutron and light particle production. This result goes against the long held belief in the space radiation shielding community that increasing shielding thickness will decrease risk to crew health. A comprehensive modeling effort was undertaken to verify the preliminary modeling results using multiple Monte Carlo and deterministic space radiation transport codes. These results verified the preliminary findings of a minimum and helped drive the design of the experimental component of the project. In first-of-their-kind experiments performed at the NASA Space Radiation Laboratory, neutrons and light ions were measured between large thicknesses of aluminum shielding. Both an upstream and a downstream shield were incorporated into the experiment to represent the radiation environment inside a spacecraft. These measurements are used to validate the Monte Carlo codes and derive uncertainty distributions for exposure estimates behind thick shielding similar to that provided by spacecraft on a Mars mission. Preliminary results for all aspects of the project will be presented.

  8. Influence of bismuth shielding use in the dose CT and the imaging quality in standard brain protocol; Influencia del uso de un protector ocular de bismuto sobre el indice de dosis TC y el ruido de la imagen en un protocolo de craneo estandar

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Carnoma, G.; Urena Llinares, A.; Santos Rubio, A.; Haro Madero, G.; Herrador Cordoba, M.

    2006-07-01

    The purpose of this work is to evaluate the reduction of lens doses, CT dose index (CTDI) and image quality when bismuth shielding is used. Dose indexes nCDTIs,p, w were measured for a head phantom (d=16 cm) in three situations: first, without shielding, second, shielded with bismuth over the phantom surface and, last, with 2 cm between both. Four regions of interest were selected, two including the theoretical eyes position and the others 4-6 cm below them. Noise and grey level in Housfield units were also measured in all geometries. A bismuth shielding in contact or 2 cm above surface provides a dose reduction of 36% y 29% respectively. In the first case an importation of image quality appears, increasing a 55% the Housfield units in the superficial regions of interest and a growth of noise 6 times greater. Bismuth protection provides an important reduction in lens dose., in the case of dire ct incidence radiation beam. (Author)

  9. Nanocalorimetry of bismuth nanoparticles

    Science.gov (United States)

    Olson, Eric Ashley

    The properties of nanosized bismuth particles are investigated using a nanocalorimetric technique. A brief description of the experimental method and data analysis procedures is reported. Bismuth nanoparticles are found to melt at a temperature below that of bulk material, but higher than expected using the standard model. Also included is the results of a finite element analysis and simulated melting of bismuth films on various kinds of sensors. Temperature distributions are found to be nonuniform for calorimetric sensors with Al metallizations, but much more uniform for Pt metallized sensors. The consequences of this nonuniformity on caloric data are discussed.

  10. Mineral resource of the month: bismuth

    Science.gov (United States)

    Carlin, James F.

    2006-01-01

    Bismuth compounds are most known for their soothing effects on the stomach, wounds and sores. These properties make the compounds an essential part of many medicinal and cosmetic preparations, which until 1930 accounted for about 90 percent of the bismuth used. The subsequent development of low-melting alloys and chemical catalysts containing bismuth, as well as its use as an additive to casting alloys, has resulted in a wider variety of industrial applications for bismuth.

  11. In vitro cytotoxicity of surface modified bismuth nanoparticles.

    Science.gov (United States)

    Luo, Yang; Wang, Chaoming; Qiao, Yong; Hossain, Mainul; Ma, Liyuan; Su, Ming

    2012-10-01

    This paper describes in vitro cytotoxicity of bismuth nanoparticles revealed by three complementary assays (MTT, G6PD, and calcein AM/EthD-1). The results show that bismuth nanoparticles are more toxic than most previously reported bismuth compounds. Concentration dependent cytotoxicities have been observed for bismuth nanoparticles and surface modified bismuth nanoparticles. The bismuth nanoparticles are non-toxic at concentration of 0.5 nM. Nanoparticles at high concentration (50 nM) kill 45, 52, 41, 34 % HeLa cells for bare nanoparticles, amine terminated bismuth nanoparticles, silica coated bismuth nanoparticles, and polyethylene glycol (PEG) modified bismuth nanoparticles, respectively; which indicates cytotoxicity in terms of cell viability is in the descending order of amine terminated bismuth nanoparticles, bare bismuth nanoparticles, silica coated bismuth nanoparticles, and PEG modified bismuth nanoparticles. HeLa cells are more susceptible to toxicity from bismuth nanoparticles than MG-63 cells. The simultaneous use of three toxicity assays provides information on how nanoparticles interact with cells. Silica coated bismuth nanoparticles can damage cellular membrane yet keep mitochondria less influenced; while amine terminated bismuth nanoparticles can affect the metabolic functions of cells. The findings have important implications for caution of nanoparticle exposure and evaluating toxicity of bismuth nanoparticles.

  12. Characterization of a lead breast shielding for dose reduction in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Correia, Paula Duarte; Brochi, Marco Aurelio Corte; Azevedo-Marques, Paulo Mazzoncini de, E-mail: pauladuarte@usp.br [Universidade de Sao Paulo (FM/RSP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina; Granzotti, Cristiano Roberto Fabri; Santos, Yago da Silva [Universidade de Sao Paulo (FFCLRP/RSP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras

    2014-07-15

    Objective: several studies have been published regarding the use of bismuth shielding to protect the breast in computed tomography (CT) scans and, up to the writing of this article, only one publication about barium shielding was found. The present study was aimed at characterizing, for the first time, a lead breast shielding. Materials and methods: the percentage dose reduction and the influence of the shielding on quantitative imaging parameters were evaluated. Dose measurements were made on a CT equipment with the aid of specific phantoms and radiation detectors. A processing software assisted in the qualitative analysis evaluating variations in average CT number and noise on images. Results: the authors observed a reduction in entrance dose by 30% and in CTDIvol by 17%. In all measurements, in agreement with studies in the literature, the utilization of cotton fiber as spacer object reduced significantly the presence of artifacts on the images. All the measurements demonstrated increase in the average CT number and noise on the images with the presence of the shielding. Conclusion: as expected, the data observed with the use of lead shielding were of the same order as those found in the literature about bismuth shielding. (author)

  13. Deep scientific drilling results from Koyna and Killari earthquake regions reveal why Indian shield lithosphere is unusual, thin and warm

    Directory of Open Access Journals (Sweden)

    O.P. Pandey

    2016-09-01

    Full Text Available The nature of crustal and lithospheric mantle evolution of the Archean shields as well as their subsequent deformation due to recent plate motions and sustained intraplate geodynamic activity, has been a subject of considerable interest. In view of this, about three decades ago, a new idea was put forward suggesting that out of all shield terrains, the Indian shield has an extremely thin lithosphere (∼100 km, compared to 250–350 km, elsewhere, apart from being warm, non-rigid, sheared and deformed. As expected, it met with scepticism by heat flow and the emerging seismic tomographic study groups, who on the contrary suggested that the Indian shield has a cool crust, besides a coherent and thick lithosphere (as much as 300–400 km like any other shield. However, recently obtained integrated geological and geophysical findings from deep scientific drillings in 1993 Killari (Mw: 6.3 and 1967 Koyna (Mw: 6.3 earthquake zones, as well as newly acquired geophysical data over other parts of Indian shield terrain, have provided a totally new insight to this debate. Beneath Killari, the basement was found consisting of high density, high velocity mid crustal amphibolite to granulite facies rocks due to exhumation of the deeper crustal layers and sustained granitic upper crustal erosion. Similar type of basement appears to be present in Koyna region too, which is characterized by considerably high upper crustal temperatures. Since, such type of crust is depleted in radiogenic elements, it resulted into lowering of heat flow at the surface, increase in heat flow contribution from the mantle, and upwarping of the lithosphere-asthenosphere boundary. Consequently, the Indian shield lithosphere has become unusually thin and warm. This study highlights the need of an integrated geological, geochemical and geophysical approach in order to accurately determine deep crust-mantle thermal regime in continental areas.

  14. Deep scientific drilling results from Koyna and Killari earthquake regions reveal why Indian shield lithosphere is unusual, thin and warm

    Institute of Scientific and Technical Information of China (English)

    O.P. Pandey

    2016-01-01

    The nature of crustal and lithospheric mantle evolution of the Archean shields as well as their subse-quent deformation due to recent plate motions and sustained intraplate geodynamic activity, has been a subject of considerable interest. In view of this, about three decades ago, a new idea was put forward suggesting that out of all shield terrains, the Indian shield has an extremely thin lithosphere (w100 km, compared to 250e350 km, elsewhere), apart from being warm, non-rigid, sheared and deformed. As expected, it met with scepticism by heat flow and the emerging seismic tomographic study groups, who on the contrary suggested that the Indian shield has a cool crust, besides a coherent and thick lithosphere (as much as 300e400 km) like any other shield. However, recently obtained integrated geological and geophysical findings from deep scientific drillings in 1993 Killari (Mw: 6.3) and 1967 Koyna (Mw: 6.3) earthquake zones, as well as newly acquired geophysical data over other parts of Indian shield terrain, have provided a totally new insight to this debate. Beneath Killari, the basement was found consisting of high density, high velocity mid crustal amphibolite to granulite facies rocks due to exhumation of the deeper crustal layers and sustained granitic upper crustal erosion. Similar type of basement appears to be present in Koyna region too, which is characterized by considerably high upper crustal temperatures. Since, such type of crust is depleted in radiogenic elements, it resulted into lowering of heat flow at the surface, increase in heat flow contribution from the mantle, and upwarping of the lithosphere-asthenosphere boundary. Consequently, the Indian shield lithosphere has become unusually thin and warm. This study highlights the need of an integrated geological, geochemical and geophysical approach in order to accurately determine deep crust-mantle thermal regime in continental areas.

  15. Novel Bismuth Nanotubes

    Institute of Scientific and Technical Information of China (English)

    苏长荣; 李家明

    2002-01-01

    Theoretical investigations show that bismuth nanotubes are semiconductors for all diameters. For smalldiameter bismuth nanotubes, the band structures and bandgaps vary strongly with the strong hybridization effect. When the diameters are larger than 18 A, the bandgaps ofBi (n, n) and (n, 0) nanotubes approach 0.63 e V, corresponding to the bandgap of bismuth sheet at the Γ point. Thus, bismuth nanotubes are expected to be a potential semiconductor nanomaterial in future nanoelectronics.

  16. Analysis of MIR-18 results for physical and biological dosimetry: radiation shielding effectiveness in LEO

    Science.gov (United States)

    Cucinotta, F. A.; Wilson, J. W.; Williams, J. R.; Dicello, J. F.

    2000-01-01

    We compare models of radiation transport and biological response to physical and biological dosimetry results from astronauts on the Mir space station. Transport models are shown to be in good agreement with physical measurements and indicate that the ratio of equivalent dose from the Galactic Cosmic Rays (GCR) to protons is about 3/2:1 and that this ratio will increase for exposures to internal organs. Two biological response models are used to compare to the Mir biodosimetry for chromosome aberration in lymphocyte cells; a track-structure model and the linear-quadratic model with linear energy transfer (LET) dependent weighting coefficients. These models are fit to in vitro data for aberration formation in human lymphocytes by photons and charged particles. Both models are found to be in reasonable agreement with data for aberrations in lymphocytes of Mir crew members: however there are differences between the use of LET dependent weighting factors and track structure models for assigning radiation quality factors. The major difference in the models is the increased effectiveness predicted by the track model for low charge and energy ions with LET near 10 keV/micrometers. The results of our calculations indicate that aluminum shielding, although providing important mitigation of the effects of trapped radiation, provides no protective effect from the galactic cosmic rays (GCR) in low-earth orbit (LEO) using either equivalent dose or the number of chromosome aberrations as a measure until about 100 g/cm 2 of material is used.

  17. Trends in Method of Diagnosis of Type 2 Diabetes Mellitus: Results from SHIELD

    Directory of Open Access Journals (Sweden)

    Helena W. Rodbard

    2009-01-01

    Full Text Available Aims. This study assessed whether recent screening recommendations have led to increased diagnosis of type 2 diabetes mellitus (T2DM through routine screening. Methods. Respondents to the 2006 US SHIELD survey reported whether a physician told them they had T2DM, age at diagnosis, specialty of the physician who made the diagnosis, and whether the diagnosis was made after having symptoms, during routine screening, or when being treated for another health problem. Results. Of 3 022 T2DM respondents, 36% of respondents reported that T2DM diagnosis was made during routine screening alone, 20% after having symptoms alone, and 6% when being treated for another health problem alone. The proportion of T2DM respondents reporting a diagnosis based only on screening increased approximately 42% over a 15+-year time span (absolute increase from 31% to 44% (P<.001, whereas symptom-based diagnosis did not change significantly (P=.10. T2DM was diagnosed primarily by family physicians (88.3%. Conclusion. These findings highlight the importance of regular screening for diabetes and the vital role of primary care physicians in recognizing individuals with T2DM.

  18. A bismuth activation counter for high sensitivity pulsed 14 MeV neutrons

    Science.gov (United States)

    Burns, E. J. T.; Thacher, P. D.; Hassig, G. J.; Decker, R. D.; Romero, J. A.; Barrett, K. P.

    2011-08-01

    We have built a fast neutron bismuth activation counter that measures activation counts from pulsed 14-MeV neutron generators for incident neutron fluences between 30 and 300 neutrons/cm2 at 15.2 cm (6 in.). The activation counter consists of a large bismuth germanate (BGO) detector surrounded by a bismuth metal shield in front of and concentric with the cylindrical detector housing. The 14 MeV neutrons activate the 2.6-millisecond (ms) isomer in the shield and the detector by the reaction 209Bi (n,2nγ) 208mBi. The use of millisecond isomers and activation counting times minimizes the background from other activated materials and the environment. In addition to activation, the bismuth metal shields against other outside radiation sources. We have tested the bismuth activation counter, simultaneously, with two data acquisition systems (DASs) and both give similar results. The two-dimensional (2D) DAS and three dimensional (3D) DAS both consist of pulse height analysis (PHA) systems that can be used to discriminate against gamma radiations below 300 keV photon energy, so that the detector can be used strictly as a counter. If the counting time is restricted to less than 25 ms after the neutron pulse, there are less than 10 counts of background for single pulse operation in all our operational environments tested so far. High-fluence neutron generator operations are restricted by large dead times and pulse height saturation. When we operate our 3D DAS PHA system in list mode acquisition (LIST), real-time corrections to dead time or live time can be made on the scale of 1 ms time windows or dwell times. The live time correction is consistent with nonparalyzable models for dead time of 1.0±0.2 μs for our 3D DAS and 1.5±0.3 μs for our 2D DAS dominated by our fixed time width analog to digital converters (ADCs). With the same solid angle, we have shown that the bismuth activation counter has a factor of 4 increase in sensitivity over our lead activation counter

  19. Gravimetric Analysis of Bismuth in Bismuth Subsalicylate Tablets: A Versatile Quantitative Experiment for Undergraduate Laboratories

    Science.gov (United States)

    Davis, Eric; Cheung, Ken; Pauls, Steve; Dick, Jonathan; Roth, Elijah; Zalewski, Nicole; Veldhuizen, Christopher; Coeler, Joel

    2015-01-01

    In this laboratory experiment, lower- and upper-division students dissolved bismuth subsalicylate tablets in acid and precipitated the resultant Bi[superscript 3+] in solution with sodium phosphate for a gravimetric determination of bismuth subsalicylate in the tablets. With a labeled concentration of 262 mg/tablet, the combined data from three…

  20. Effect of phase stability degradation of bismuth on sensor characteristics of nano-bismuth fixed electrode.

    Science.gov (United States)

    Lee, Gyoung-Ja; Kim, Chang Kyu; Lee, Min Ku; Rhee, Chang Kyu

    2010-12-15

    Effect of phase stability degradation of bismuth on sensor characteristics of nano-bismuth fixed electrode has been investigated using square-wave anodic stripping voltammetry technique, scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectroscopy. From the analyses of square-wave anodic stripping voltammograms (SWASV) repetitively measured on the nano-bismuth fixed electrode, it was found that the oxidation peak currents dropped by 81%, 68% and 59% for zinc, cadmium and lead, respectively, after the 100th measurement (about 400 min of operation time). The sphere bismuth nanoparticles gradually changed to the agglomerates with petal shape as the operation time increased. From the analyses of SEM images and XRD patterns, it is confirmed that the oxidation of Bi into BiOCl/Bi(2)O(2)CO(3) and the agglomeration of bismuth nanoparticles caused by the phase change decrease a reproducibility of the stripping voltammetric response. Moreover, most of the bismuth becomes BiOCl at pH 3.0 and bismuth hydroxide, Bi(OH)(3) at pH 7.0, which results in a significant decrease in sensitivity of the nano-bismuth fixed electrode.

  1. Electrochemical properties of porous bismuth electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Romann, T., E-mail: tavo.romann@ut.e [Institute of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu (Estonia); Lust, E. [Institute of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu (Estonia)

    2010-08-01

    The properties of Bi surfaces with different roughnesses were characterized by electron microscopy, cyclic voltammetry, and impedance spectroscopy. Two different strategies were used for preparation of porous bismuth layers onto Bi microelectrode surface in aqueous 0.1 M LiClO{sub 4} solution. Firstly, treatment at potential E < -2 V (vs. Ag|AgCl in sat. KCl) has been applied, resulting in bismuth hydride formation and decomposition into Bi nanoparticles which deposit at the electrode surface. Secondly, porous Bi layer was prepared by anodic dissolution (E = 1 V) of bismuth electrode followed by fast electroreduction of formed Bi{sup 3+} ions at cathodic potentials E = -2 V. The nanostructured porous bismuth electrode, with surface roughness factor up to 220, has negligible frequency dispersion of capacitance and higher hydrogen evolution overvoltage than observed for smooth Bi electrodes.

  2. Thermoelectric properties of pressed bismuth nanoparticles

    Science.gov (United States)

    Hostler, Stephen R.; Qu, Yu Qiao; Demko, Michael T.; Abramson, Alexis R.; Qiu, Xiaofeng; Burda, Clemens

    2008-03-01

    Theory predicts a substantial increase in the dimensionless figure of merit as the dimensionality and characteristic size of a material are decreased. We explore the use of bismuth nanoparticles pressed into pellets as potential increased efficiency thermoelectric materials. The figure of merit of these pellets is determined by independently measuring the electrical conductivity, thermal conductivity and Seebeck coefficient. The results from the nanoparticle sample are compared to microparticle-based samples. Both sample types show a slight reduction in thermal conductivity relative to bulk bismuth and a Seebeck coefficient near or slightly larger in magnitude than bulk bismuth. These changes are dwarfed by a hundred-fold decrease in the electrical conductivity due to porosity and an oxide layer on the particles. The low conductivity leads to figures of merit at least two orders of magnitude smaller than bulk bismuth. Oxide layer removal and reduced pellet porosity will be required to increase the figure of merit.

  3. Design of Light Multi-layered Shields for Use in Diagnostic Radiology and Nuclear Medicine via MCNP5 Monte Carlo Code

    Directory of Open Access Journals (Sweden)

    Mehdi Zehtabian

    2015-09-01

    Full Text Available Introduction Lead-based shields are the most widely used attenuators in X-ray and gamma ray fields. The heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. Materials and Methods The purpose of this study was to design multi-layered shields for protection against X-rays and gamma rays in diagnostic radiology and nuclear medicine. In this study, cubic slabs composed of several materials with high atomic numbers, i.e., lead, barium, bismuth, gadolinium, tin and tungsten, were simulated, using MCNP5 Monte Carlo code. Cubic slabs (30×30×0.05 cm3 were simulated at a 50 cm distance from the point photon source. The X-ray spectra of 80 kVp and 120 kVp were obtained, using IPEM Report 78. The photon flux following the use of each shield was obtained inside cubic tally cells (1×1×0.5 cm3 at a 5 cm distance from the shields. The photon attenuation properties of multi-layered shields (i.e., two, three, four and five layers, composed of non-lead radiation materials, were also obtained via Monte Carlo simulations. Results Among different shield designs proposed in this study, the three-layered shield, composed of tungsten, bismuth and gadolinium, showed the most significant attenuation properties in radiology, with acceptable shielding at 140 keV energy in nuclear medicine. Conclusion According to the results, materials with k-edges equal to energies common to diagnostic radiology can be proper substitutes for lead shields.

  4. Flame spray synthesis under a non-oxidizing atmosphere: Preparation of metallic bismuth nanoparticles and nanocrystalline bulk bismuth metal

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Robert N.; Stark, Wendelin J. [Institute for Chemical and Bioengineering, ETH Zuerich (Switzerland)], E-mail: wendelin.stark@chem.ethz.ch

    2006-10-15

    Metallic bismuth nanoparticles of over 98% purity were prepared by a modified flame spray synthesis method in an inert atmosphere by oxygen-deficient combustion of a bismuth-carboxylate based precursor. The samples were characterized by X-ray diffraction, thermal analysis and scanning electron microscopy confirming the formation of pure, crystalline metallic bismuth nanoparticles. Compression of the as-prepared powder resulted in highly dense, nanocrystalline pills with strong electrical conductivity and bright metallic gloss.

  5. Structure of unsupported bismuth nanoparticles

    Science.gov (United States)

    Wurl, A.; Hyslop, M.; Brown, S. A.; Hall, B. D.; Monot, R.

    We present new results of electron diffraction experiments on unsupported nanometer-sized bismuth clusters. The high intensity cluster beam, necessary for electron diffraction, is provided by an inert-gas aggregation source. The cluster beam contains particles with average cluster sizes between 4.5 and 10 nm. When using Helium as a carrier gas we are able to observe a transition from crystalline clusters to a new structure, which we identify with that of amorphous or liquid clusters.

  6. Fetal shielding combined with state of the art CT dose reduction strategies during maternal chest CT

    Energy Technology Data Exchange (ETDEWEB)

    Chatterson, Leslie C., E-mail: lch088@mail.usask.ca [Department of Diagnostic Imaging, University of Saskatchewan (Canada); Leswick, David A.; Fladeland, Derek A. [Department of Diagnostic Imaging, University of Saskatchewan (Canada); Hunt, Megan M.; Webster, Stephen [Saskatchewan Ministry of Labour Relations and Workplace Safety (Canada); Lim, Hyun [Department of Community Health and Epidemiology, College of Medicine, University of Saskatchewan (Canada)

    2014-07-15

    Purpose: Custom bismuth-antimony shields were previously shown to reduce fetal dose by 53% on an 8DR (detector row) CT scanner without dynamic adaptive section collimation (DASC), automatic tube current modulation (ATCM) or adaptive statistical iterative reconstruction (ASiR). The purpose of this study is to compare the effective maternal and average fetal organ dose reduction both with and without bismuth-antimony shields on a 64DR CT scanner using DASC, ATCM and ASiR during maternal CTPA. Materials and methods: A phantom with gravid prosthesis and a bismuth-antimony shield were used. Thermoluminescent dosimeters (TLDs) measured fetal radiation dose. The average fetal organ dose and effective maternal dose were determined using 100 kVp, scanning from the lung apices to the diaphragm utilizing DASC, ATCM and ASiR on a 64DR CT scanner with and without shielding in the first and third trimester. Isolated assessment of DASC was done via comparing a new 8DR scan without DASC to a similar scan on the 64DR with DASC. Results: Average third trimester unshielded fetal dose was reduced from 0.22 mGy ± 0.02 on the 8DR to 0.13 mGy ± 0.03 with the conservative 64DR protocol that included 30% ASiR, DASC and ATCM (42% reduction, P < 0.01). Use of a shield further reduced average third trimester fetal dose to 0.04 mGy ± 0.01 (69% reduction, P < 0.01). The average fetal organ dose reduction attributable to DASC alone was modest (6% reduction from 0.17 mGy ± 0.02 to 0.16 mGy ± 0.02, P = 0.014). First trimester fetal organ dose on the 8DR protocol was 0.07 mGy ± 0.03. This was reduced to 0.05 mGy ± 0.03 on the 64DR protocol without shielding (30% reduction, P = 0.009). Shields further reduced this dose to below accurately detectable levels. Effective maternal dose was reduced from 4.0 mSv on the 8DR to 2.5 mSv on the 64DR scanner using the conservative protocol (38% dose reduction). Conclusion: ASiR, ATCM and DASC combined significantly reduce effective maternal and fetal

  7. Transparent Metal-Salt-Filled Polymeric Radiation Shields

    Science.gov (United States)

    Edwards, David; Lennhoff, John; Harris, George

    2003-01-01

    "COR-RA" (colorless atomic oxygen resistant -- radiation shield) is the name of a transparent polymeric material filled with x-ray-absorbing salts of lead, bismuth, cesium, and thorium. COR-RA is suitable for use in shielding personnel against bremsstrahlung radiation from electron-beam welding and industrial and medical x-ray equipment. In comparison with lead-foil and leaded-glass shields that give equivalent protection against x-rays (see table), COR-RA shields are mechanically more durable. COR-RA absorbs not only x-rays but also neutrons and rays without adverse effects on optical or mechanical performance. The formulation of COR-RA with the most favorable mechanical-durability and optical properties contains 22 weight percent of bismuth to absorb x-rays, plus 45 atomic percent hydrogen for shielding against neutrons.

  8. Seismic Interpretation and Well Logging Results of a Deep Borehole into the Canadian Shield in Northeastern Alberta: Preliminary Results

    Science.gov (United States)

    Chan, J.; Schmitt, D.; Majorowicz, J. A.; Nieuwenhuis, G.; Poureslami Ardakani, E.; van der Baan, M.; Sahay, P. N.; Kueck, J.; Abasolo, M. R.

    2011-12-01

    information about the reflectivity and the velocity structure of the subsurface. The full integration of surface seismic data, VSP data, and well logs are expected to provide a detailed characterization of the sedimentary basin and crystalline basement rocks of the Canadian Shield in Northeastern Alberta. In particular, the unusually low fluid pressures in the well may be related to states of stress that are likely still influenced by post-glacial rebound.

  9. Characterization of a lead breast shielding for dose reduction in computed tomography*

    OpenAIRE

    Correia,Paula Duarte; Granzotti, Cristiano Roberto Fabri; Santos, Yago da Silva; Brochi,Marco Aurelio Corte; Azevedo-Marques,Paulo Mazzoncini de

    2014-01-01

    Objective Several studies have been published regarding the use of bismuth shielding to protect the breast in computed tomography (CT) scans and, up to the writing of this article, only one publication about barium shielding was found. The present study was aimed at characterizing, for the first time, a lead breast shielding. Materials and Methods The percentage dose reduction and the influence of the shielding on quantitative imaging parameters were evaluated. Dose measurements were made on ...

  10. The Borodinskii Massif of potassium porphyric granite: Results of U-Pb dating and its tectonic position (Fennoscandian Shield)

    Science.gov (United States)

    Baltybaev, Sh. K.; Rizvanova, N. G.; Glebovitsky, V. A.

    2016-09-01

    It has been demonstrated for the first time that the Svecofennian crustal porphyric granites in the southeastern part of the Fennoscandian Shield are clearly subdivided into two age groups of 1.87 and 1.80 Ga. The representative of the first group is the Kuznechenskii Massif of porphyric granites with a U-Pb age of 1874 ± 4 Ma belongs to the group of plutons formed during the orogenic stage of Svecofennide evolution. The Borodinskii Massif with an age of 1797 ± 2 Ma is a member of the second group: these plutons were formed under tectonically stable (epiplatform) conditions. Therefore, the formation of porphyric granites occurred as the result of repeated generation of crustal magmas during multistage accretional growth of the Svecofennian crust.

  11. Bismuth-Based Quadruple Therapy with Bismuth Subcitrate, Metronidazole, Tetracycline and Omeprazole in the Eradication of Helicobacter pylori

    Directory of Open Access Journals (Sweden)

    Raymond Lahaie

    2001-01-01

    Full Text Available BACKGROUND: A previous study showed that 14 days of qid bismuth-based triple therapy with tetracycline 500 mg, metronidazole 250 mg and colloidal bismuth subcitrate 120 mg resulted in excellent Helicobacter pylori eradication rates (89.5%. The present study looked at a shorter treatment period by adding omeprazole and by reducing the dose of tetracycline.

  12. Bismuth vanadate process

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, R.M.

    1990-06-26

    This patent describes the process for the preparation of bismuth vanadate and bismuth vanadate-containing compounds wherein the precursor materials are calcined in the solid state at temperatures sufficient to react the precursor materials to prepare the vanadate compounds. It comprises: wet grinding the calcined product, contacting the calcined product with sufficient alkaline material to provide a pH level of 7.0-13.0 and recovering the treated product, the wet grinding of the calcined product being conducted either in the presence of the alkaline material or prior to the contacting with the alkaline material.

  13. Shields-1, A SmallSat Radiation Shielding Technology Demonstration

    Science.gov (United States)

    Thomsen, D. Laurence, III; Kim, Wousik; Cutler, James W.

    2015-01-01

    The NASA Langley Research Center Shields CubeSat initiative is to develop a configurable platform that would allow lower cost access to Space for materials durability experiments, and to foster a pathway for both emerging and commercial-off-the-shelf (COTS) radiation shielding technologies to gain spaceflight heritage in a relevant environment. The Shields-1 will be Langleys' first CubeSat platform to carry out this mission. Radiation shielding tests on Shields-1 are planned for the expected severe radiation environment in a geotransfer orbit (GTO), where advertised commercial rideshare opportunities and CubeSat missions exist, such as Exploration Mission 1 (EM-1). To meet this objective, atomic number (Z) graded radiation shields (Zshields) have been developed. The Z-shield properties have been estimated, using the Space Environment Information System (SPENVIS) radiation shielding computational modeling, to have 30% increased shielding effectiveness of electrons, at half the thickness of a corresponding single layer of aluminum. The Shields-1 research payload will be made with the Z-graded radiation shields of varying thicknesses to create dose-depth curves to be compared with baseline materials. Additionally, Shields-1 demonstrates an engineered Z-grade radiation shielding vault protecting the systems' electronic boards. The radiation shielding materials' performances will be characterized using total ionizing dose sensors. Completion of these experiments is expected to raise the technology readiness levels (TRLs) of the tested atomic number (Z) graded materials. The most significant contribution of the Z-shields for the SmallSat community will be that it enables cost effective shielding for small satellite systems, with significant volume constraints, while increasing the operational lifetime of ionizing radiation sensitive components. These results are anticipated to increase the development of CubeSat hardware design for increased mission lifetimes, and enable

  14. Volcanic edifice alignment detection software in MATLAB: Test data and preliminary results for shield fields on Venus

    Science.gov (United States)

    Thomson, Bradley J.; Lang, Nicholas P.

    2016-08-01

    The scarcity of impact craters on Venus make it difficult to infer the relative ages of geologic units. Stratigraphic methods can be used to help infer the relative ordering of surface features, but the relatively coarse resolution of available radar data means ambiguity about the timing of certain features is common. Here we develop a set of statistical tools in MATLAB to help infer the relative timing between clusters of small shield volcanoes and sets of fractures in the surrounding terrain. Specifically, we employed two variants of the two-point azimuth method to detect anisotropy in the distribution of point-like features. The results of these methods are shown to successfully identify anisotropy at two spatial scales: at the whole-field level and at scales smaller than a set fraction of the mean value. Initial results on the test cases presented here are promising, at least for volcanic fields emplaced under uniform conditions. These methods could also be used for detecting anisotropy in other point-like geologic features, such as hydrothermal vents, springs, and earthquake epicenters.

  15. Shielding Effectiveness of Laminated Shields

    Directory of Open Access Journals (Sweden)

    B. P. Rao

    2008-12-01

    Full Text Available Shielding prevents coupling of undesired radiated electromagnetic energy into equipment otherwise susceptible to it. In view of this, some studies on shielding effectiveness of laminated shields with conductors and conductive polymers using plane-wave theory are carried out in this paper. The plane wave shielding effectiveness of new combination of these materials is evaluated as a function of frequency and thickness of material. Conductivity of the polymers, measured in previous investigations by the cavity perturbation technique, is used to compute the overall reflection and transmission coefficients of single and multiple layers of the polymers. With recent advances in synthesizing stable highly conductive polymers these lightweight mechanically strong materials appear to be viable alternatives to metals for EM1 shielding.

  16. Bismuth incorporation into gallium phosphide

    Energy Technology Data Exchange (ETDEWEB)

    Jena, Puru [Virginia Commonwealth Univ. (United States); Kandalam, Anil K. [West Chester Univ. of Pennsylvania (United States); Christian, Theresa M. [National Renewable Energy Lab. (United States); Beaton, Daniel A. [National Renewable Energy Lab. (United States); Mascarenhas, Angelo [National Renewable Energy Lab. (United States); Alberi, Kirstin [National Renewable Energy Lab. (United States)

    2016-12-21

    Gallium phosphide bismide (GaP1-xBix) epilayers with bismuth fractions from 0.9% to 3.2%, as calculated from lattice parameter measurements, were studied with Rutherford backscattering spectrometry (RBS) to directly measure bismuth incorporation. The total bismuth fractions found by RBS were higher than expected from the lattice parameter calculations. Furthermore, in one analyzed sample grown by molecular beam epitaxy at 300 degrees C, 55% of incorporated bismuth was found to occupy interstitial sites. We discuss implications of this high interstitial incorporation fraction and its possible relationship to x-ray diffraction and photoluminescence measurements of GaP0.99Bi0.01.

  17. Effects of shielding the radiosensitive superficial organs of ORNL pediatric phantoms on dose reduction in computed tomography

    Directory of Open Access Journals (Sweden)

    Parisa Akhlaghi

    2014-01-01

    Full Text Available In computed tomography (CT, some superficial organs which have increased sensitivity to radiation, receive doses that are significant enough to be matter of concern. Therefore, in this study, the effects of using shields on the amount of dose reduction and image quality was investigated for pediatric imaging. Absorbed doses of breasts, eyes, thyroid and testes of a series of pediatric phantoms without and with different thickness of bismuth and lead were calculated by Monte Carlo simulation. Appropriate thicknesses of shields were chosen based on their weights, X-ray spectrum, and the amount of dose reduction. In addition, the effect of lead shield on image quality of a simple phantom was assessed quantitatively using region of interest (ROI measurements. Considering the maximum reduction in absorbed doses and X-ray spectrum, using a lead shield with a maximum thickness of 0.4 mm would be appropriate for testes and thyroid and two other organs (which are exposed directly should be protected with thinner shields. Moreover, the image quality assessment showed that lead was associated with significant increases in both noise and CT attenuation values, especially in the anterior of the phantom. Overall, the results suggested that shielding is a useful optimization tool in CT.

  18. Layered bismuth vanadate ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Osipyan, V.G.; Savchenko, L.M.; Elbakyan, V.L.; Avakyan, P.B.

    1987-08-01

    The authors synthesize new layered bismuth vanadate ferroelectrics. The x-ray diffraction characteristics of Bi/sub 2/VO/sub 5.5/ are shown. Thermal expansion of ceramics with various compositions are presented, as are the temperature dependences of the dielectric constant of the ceramic with various compositions. Unit-cell parameters, Curie temperature, electrical conductivity and the dielectric characteristics of the compositions studied are shown.

  19. THORIUM DISPERSION IN BISMUTH

    Science.gov (United States)

    Bryner, J.S.

    1961-07-01

    The growth of thorium bismutaide particles, which are formed when thorium is suspended in liquid bismuth, is inhibited when the liquid metal suspension is being flowed through a reactor and through a heat exchanger in sequence. It involves the addition of as little as 1 part by weight of tellurium to 100 parts of thorium. This addition is sufficient to inhibit particle growth and agglomeration.

  20. Shielding analysis at the upper section of the accelerator-driven system.

    Science.gov (United States)

    Sasa, Toshinobu; Yang, Jin An; Oigawa, Hiroyuki

    2005-01-01

    The proton beam duct of the accelerator-driven system (ADS) acts as a streaming path for spallation neutrons and photons and causes the activation of the magnets and other devices above the subcritical core. We have performed a streaming analysis at the upper section of the lead-bismuth target/cooled ADS (800 MWth). MCNPX was used to calculate the radiation dose from streamed neutrons and photons through the beam duct. For the secondary photon production calculation, cross sections for several actinides were substituted with plutonium because of the lack of gamma production cross section. From the results of this analysis, the neutron dose from the beam duct is seen to be about 20 orders higher than that of the bulk shield. The magnets and shield plug are heavily irradiated by streaming neutrons according to the DCHAIN-SP analysis.

  1. Effect of Lipophilic Bismuth Nanoparticles on Erythrocytes

    Directory of Open Access Journals (Sweden)

    Rene Hernandez-Delgadillo

    2015-01-01

    Full Text Available Lipophilic bismuth dimercaptopropanol nanoparticles (BisBAL NPs have a very important antimicrobial activity; however their effect on human cells or tissues has not been completely studied. Undesirable effects of bismuth include anemia which could result from suicidal erythrocyte death or eryptosis. The objective of this research was to determine the effect of bismuth dimercaptopropanol nanoparticles on blood cells. The nanoparticles are composed of 53 nm crystallites on average and have a spherical structure, agglomerating into clusters of small nanoparticles. Based on cell viability assays and optical microscopy, cytotoxicity on erythrocytes was observed after growing with 500 and 1000 µM of BisBAL NPs for 24 h. AM Calcein was retained inside erythrocytes when they were exposed to 100 µM (or lower concentrations of BisBAL NPs for 24 h, suggesting the absence of damage in plasmatic membrane. Genotoxic assays revealed no damage to genomic DNA of blood cells after 24 h of exposition to BisBAL NPs. Finally, 100–1000 µM of bismuth nanoparticles promotes apoptosis between blood cells after 24 h of incubation. Hence BisBAL NPs at concentrations lower than 100 µM do not cause damage on blood cells; they could potentially be used by humans without affecting erythrocytes and leukocytes.

  2. Tribochemistry of Bismuth and Bismuth Salts for Solid Lubrication

    NARCIS (Netherlands)

    Gonzalez Rodriguez, P.; Nieuwenhuijzen, van den K.J.H.; Lette, W.; Schipper, D.J.; Elshof, ten J.E.

    2016-01-01

    One of the main trends in the past decades is the reduction of wastage and the replacement of toxic compounds in industrial processes. Some soft metallic particles can be used as nontoxic solid lubricants in high-temperature processes. The behavior of bismuth metal particles, bismuth sulfide (Bi2S3)

  3. Bismuth toxicity in patients treated with bismuth iodoform paraffin packs.

    Science.gov (United States)

    Atwal, A; Cousin, G C S

    2016-01-01

    Bismuth is a heavy metal used in bismuth iodoform paraffin paste (BIPP) antiseptic dressings and in a number of other medical preparations. It can be absorbed systemically and cause toxicity. We report 2 cases of such neurotoxicity after it was used in operations on the jaws.

  4. Melting and solidification of bismuth inclusions in aluminium

    DEFF Research Database (Denmark)

    Thoft, N.B.; Bohr, J.; Buras, B.

    1995-01-01

    Supercooling of crystalline bismuth inclusions in aluminium crystals has been observed and studied with different techniques: x-ray diffraction, in situ Rutherford backscattering/channelling spectrometry and transmission electron microscopy. The results of the measurements with different experime......Supercooling of crystalline bismuth inclusions in aluminium crystals has been observed and studied with different techniques: x-ray diffraction, in situ Rutherford backscattering/channelling spectrometry and transmission electron microscopy. The results of the measurements with different...

  5. Spin dynamics of complex oxides, bismuth-antimony alloys, and bismuth chalcogenides

    Science.gov (United States)

    Sahin, Cuneyt

    The emerging field of spintronics relies on the manipulation of electron spin in order to use it in spin-based electronics. Such a paradigm change has to tackle several challenges including finding materials with sufficiently long spin lifetimes and materials which are efficient in generating pure spin currents. This thesis predicts that two types of material families could be a solution to the aforementioned challenges: complex oxides and bismuth based materials. We derived a general approach for constructing an effective spin-orbit Hamiltonian which is applicable to all nonmagnetic materials. This formalism is useful for calculating spin-dependent properties near an arbitrary point in momentum space. We also verified this formalism through comparisons with other approaches for III-V semiconductors, and its general applicability is illustrated by deriving the spin-orbit interaction and predicting spin lifetimes for strained strontium titanate (STO) and a two-dimensional electron gas in STO (such as at the LAO/STO interface). Our results suggest robust spin coherence and spin transport properties in STO related materials even at room temperature. In the second part of the study we calculated intrinsic spin Hall conductivities for bismuth-antimony (BISb) semimetals with strong spin-orbit couplings, from the Kubo formula and using Berry curvatures evaluated throughout the Brillouin zone from a tight-binding Hamiltonian. Nearly crossing bands with strong spin-orbit interaction generate giant spin Hall conductivities in these materials, ranging from 474 ((h/e)O--1cm--1) for bismuth to 96((h/e)O--1cm --1) for antimony; the value for bismuth is more than twice that of platinum. The large spin Hall conductivities persist for alloy compositions corresponding to a three-dimensional topological insulator state, such as Bi0.83Sb0.17. The spin Hall conductivity could be changed by a factor of 5 for doped Bi, or for Bi0.83Sb0.17, by changing the chemical potential by 0.5 e

  6. Bismuth(V) oxide and silver bismuthate as oxidizing agents for gas-chromatographic elemental microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Shvykin, A.Y.; Platonov, V.V.; Proskuryakov, V.P.; Chilachava, K.B.; Khmarin, E.M.; Kovtun, I.V. [Tolstoy State Pedag University, Tula (Russian Federation)

    2004-07-01

    Bismuth(V) oxide, silver bismuthate, and a mixture of bismuth(V) oxide with fine silver powder were studied as oxidizing additives in gas-chromatographic elemental microanalysis of readily combustible organic substances and coal.

  7. Bismuth ochers from San Diego Co., California

    Science.gov (United States)

    Schaller, W.T.

    1911-01-01

    The chief points brought out in this paper may be briefly summarized as follows: (1) The existence of natural Bi2O3 has not been established. (2) Natural bismite or bismuth ocher, when pure, is more probably a bismuth hydroxide. (3) The bismuth ochers from San Diego County, California, are either a bismuth hydroxide or bismuth vanadate, pucherite, or mixtures of these two. (4) Pucherite has been found noncrystallin and determined for the first time in the United States.

  8. Dielectric spectra of bismuth vanadate Bi4V2O11

    Energy Technology Data Exchange (ETDEWEB)

    Borisov, V.N.; Pashkov, V.M.; Poplavko, IU.M.; Avakian, P.B.; Osipian, V.G. (Kievskii Politekhnicheskii Institut, Kiev (Ukrainian SSR))

    1990-06-01

    Results of a study of the temperature-frequency dependence of the behavior of the dielectric parameters of bismuth vanadate, Bi4V2O11, in the frequency range 1-100 GHz are reported. It is shown that bismuth vanadate is characterized by a large number of phase transitions. Yet another, previously unknown, phase transition in bismuth vanadate, masked by a relaxation process, has been observed in the temperature range 410-420 K. 12 refs.

  9. Dielectric spectra of bismuth vanadate Bi4V2O11

    Science.gov (United States)

    Borisov, V. N.; Pashkov, V. M.; Poplavko, Iu. M.; Avakian, P. B.; Osipian, V. G.

    1990-06-01

    Results of a study of the temperature-frequency dependence of the behavior of the dielectric parameters of bismuth vanadate, Bi4V2O11, in the frequency range 1-100 GHz are reported. It is shown that bismuth vanadate is characterized by a large number of phase transitions. Yet another, previously unknown, phase transition in bismuth vanadate, masked by a relaxation process, has been observed in the temperature range 410-420 K.

  10. Energetics of bismuth vanadate

    Energy Technology Data Exchange (ETDEWEB)

    Nagabhushana, G.P.; Tavakoli, A.H.; Navrotsky, A., E-mail: anavrotsky@ucdavis.edu

    2015-05-15

    Bismuth vanadate has gained considerable interest as a photoanode for water splitting reactions under visible light. It exists in four different polymorphs, out of which three of them have been synthesized. Thermodynamic properties of these three polymorphs are investigated using high temperature oxide melt solution calorimetry. The monoclinic scheelite phase which exhibits photocatalytic activity under visible light is found to be the most stable polymorph, followed by tetragonal scheelite which exhibits activity under UV light. The photocatalytically inactive tetragonal zircon form is found to be the least stable polymorph. The small difference in enthalpy of formation between the two scheelite structures (−8 kJ/mol) is in accord with the reversibility of the transformation between them and the larger difference between the most stable monoclinic phase and the least stable tetragonal zircon phase (−23 kJ/mol) is in accord with the irreversible (monoclinic→tetragonal zircon) phase transformation. - Graphical abstract: Schematic representation of polymorphic transitions in BiVO{sub 4} along with their formation enthalpies. - Highlights: • Bismuth vanadate crystallizes in three different polymorphs. • High temperature calorimetric measurements were made to determine their formation enthalpies. • Enthalpy of formation decreases in the order BV-ms→BV-ts→BV-tz. • Photocatalytically active monoclinic-BiVO{sub 4} was found to be the most stable polymorph.

  11. Measurement of the transient shielding effectiveness of shielding cabinets

    Directory of Open Access Journals (Sweden)

    H. Herlemann

    2008-05-01

    Full Text Available Recently, new definitions of shielding effectiveness (SE for high-frequency and transient electromagnetic fields were introduced by Klinkenbusch (2005. Analytical results were shown for closed as well as for non closed cylindrical shields. In the present work, the shielding performance of different shielding cabinets is investigated by means of numerical simulations and measurements inside a fully anechoic chamber and a GTEM-cell. For the GTEM-cell-measurements, a downscaled model of the shielding cabinet is used. For the simulations, the numerical tools CONCEPT II and COMSOL MULTIPHYSICS were available. The numerical results agree well with the measurements. They can be used to interpret the behaviour of the shielding effectiveness of enclosures as function of frequency. From the measurement of the electric and magnetic fields with and without the enclosure in place, the electric and magnetic shielding effectiveness as well as the transient shielding effectiveness of the enclosure are calculated. The transient SE of four different shielding cabinets is determined and discussed.

  12. Elimination of the beam effect on channeling dips of bismuth implanted in silicon

    Science.gov (United States)

    Wagh, A. G.; Radhakrishnan, S.; Gaonkar, S. G.; Kansara, M. J.

    1980-01-01

    The effect of the analysing He + ion beam has been eliminated from channeling measurements on Si(Bi) by extrapolating the plot of normalised yield against He + dose to zero ion dose. The magnitude of the beam effect varies with the angle of incidence, being minimum for beam incidence along the crystallographic axis. The axial channeling dips thus obtained exhibit similar minimum yields for bismuth and silicon. The bismuth dips are, however, narrower than for silicon. The planar channeling experiments, on the other hand, yield nearly identical bismuth and silicon dips. The results indicate that the bismuth atom occupies the substitutional site in silicon, but the lattice is strained in its vicinity.

  13. Preparation and characterisation of Isophthalic-Bi2O3 polymer composite gamma radiation shields

    Science.gov (United States)

    Ambika, M. R.; Nagaiah, N.; Harish, V.; Lokanath, N. K.; Sridhar, M. A.; Renukappa, N. M.; Suman, S. K.

    2017-01-01

    Bi2O3 filled Isophthalic resin based polymer composites of different weight % (0, 5, 10, 20, 30, 40, 50 & 60) were fabricated by open mould cast technique. Gamma attenuation study was carried out using NaI (Tl) gamma ray spectrometer for Cs-137. The shielding parameters such as attenuation coefficient, HVL & λ were investigated. The distribution of the filler within the matrix was studied using Scanning Electron Microscopy. X ray diffractometer and Fourier Transform Infrared Spectroscopy were employed to study the structural changes if any. The thermal stability and mechanical strength of the composites were investigated using TGA & UTM respectively. Dielectric properties and AC conductivity were also studied using LCR meter. The composites are found to be thermally stable upto 200 °C. There were no such structural changes observed and all the composites show very low conductivity. The mechanical strength of the composites was found to increase upon adding the bismuth oxide with a slight decrease when the concentration of the filler exceeds 40 wt%. Attenuation results reveal that, the shielding efficiency increases with the increase of the filler wt% and are comparable to those of the conventional shielding materials. Hence, Bi2O3 filled composites can be used for gamma shielding applications.

  14. Optimal biliary drainage for inoperable Klatskin's tumor based on Bismuth type

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To investigate differences in the effects of biliary drainage procedures in patients with inoperable Klatskin's tumor based on Bismuth type, considering endoscopic retrograde biliary drainage (ERBD), external percutaneous transhepatic biliary drainage (EPTBD) and internal biliary stenting via the PTBD tract (IPTBD).METHODS: The initial success rate, cumulative patency rate, and complication rate were compared retrospectively, according to the Bismuth type and ERBD,EPTBD, and IPTBD. Patency was defined as the duration for adequate initial bile drainage or to the point of the patient's death associated with inadequate drainage.RESULTS: One hundred thirty-four patients (93 men,41 women; 21 Bismuth type Ⅱ, 47 Ⅲ, 66 Ⅳ; 34 ERBD,66 EPTBD, 34 IPTBD) were recruited. There were no differences in demographics among the groups.Adequate initial relief of jaundice was achieved in 91% of patients without a significant difference in the results among different procedures or Bismuth types. The cumulative patency rates for ERBD and IPTBD were better than those for EPTBD with Bismuth type Ⅲ.IPTBD provided an excellent response for Bismuth type Ⅳ. However, there was no difference in the patency rate among drainage procedures for Bismuth type Ⅱ.Procedure-related cholangitis occurred less frequently with EPTBD than with ERBD and IPTBD.CONCLUSION: ERBD is recommended as the firstline drainage procedure for the palliation of jaundice in patients with inoperable Klatskin's tumor of Bismuth type Ⅱ or Ⅲ, but IPTBD is the best option for Bismuth type Ⅳ.

  15. Electrical resistivity of thin bismuth films

    Science.gov (United States)

    Kumar, A.; Katyal, O. P.

    1990-05-01

    The effect of the film thickness of a bismuth film deposited on glass substrate on its electrical resistivity was investigated for films from 41 to 225 nm thickness, in the temperature range 77-350 K. Results show that the electrical resistivity decreases with increasing temperature and that, for films 98.3 and 225.9 nm thick there exists a minimum (between 260 and 350 K) in resistivity at some temperature, Tc. This minimum shifts toward higher temperature for thinner samples, and lies above 350 K. The thickness dependence of the bismuth film resistivity, obtained at 77, 150, and 300 K, can be explained by a modified Fuchs model, which takes into account the thickness dependence of carrier density.

  16. Energetics of bismuth vanadate

    Science.gov (United States)

    Nagabhushana, G. P.; Tavakoli, A. H.; Navrotsky, A.

    2015-05-01

    Bismuth vanadate has gained considerable interest as a photoanode for water splitting reactions under visible light. It exists in four different polymorphs, out of which three of them have been synthesized. Thermodynamic properties of these three polymorphs are investigated using high temperature oxide melt solution calorimetry. The monoclinic scheelite phase which exhibits photocatalytic activity under visible light is found to be the most stable polymorph, followed by tetragonal scheelite which exhibits activity under UV light. The photocatalytically inactive tetragonal zircon form is found to be the least stable polymorph. The small difference in enthalpy of formation between the two scheelite structures (-8 kJ/mol) is in accord with the reversibility of the transformation between them and the larger difference between the most stable monoclinic phase and the least stable tetragonal zircon phase (-23 kJ/mol) is in accord with the irreversible (monoclinic→tetragonal zircon) phase transformation.

  17. Small Engine Technology (SET) - Task 13 ANOPP Noise Prediction for Small Engines: Jet Noise Prediction Module, Wing Shielding Module, and System Studies Results

    Science.gov (United States)

    Lieber, Lysbeth; Golub, Robert (Technical Monitor)

    2000-01-01

    This Final Report has been prepared by AlliedSignal Engines and Systems, Phoenix, Arizona, documenting work performed during the period May 1997 through June 1999, under the Small Engines Technology Program, Contract No. NAS3-27483, Task Order 13, ANOPP Noise Prediction for Small Engines. The report specifically covers the work performed under Subtasks 4, 5 and 6. Subtask 4 describes the application of a semi-empirical procedure for jet noise prediction, subtask 5 describes the development of a procedure to predict the effects of wing shielding, and subtask 6 describes the results of system studies of the benefits of the new noise technology on business and regional aircraft.

  18. Shielding structure analysis for LSDS facility

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hong Yeop; Kim, Jeong Dong; Lee, Yong Deok; Kim, Ho Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    The nuclear material (Pyro, Spent nuclear fuel) itself and the target material to generate neutrons is the LSDS system for isotopic fissile assay release of high intensity neutron and gamma rays. This research was performed to shield from various strong radiation. A shielding evaluation was carried out with a facilities model of LSDS system. The MCNPX 2.5 code was used and a shielding evaluation was performed for the shielding structure and location. The radiation dose based on the hole structure and location of the wall was evaluated. The shielding evaluation was performed to satisfy the safety standard for a normal person (1 μSv/h) and to use enough interior space. The MCNPX2.5 code was used and a dose evaluation was performed for the location of the shielding material, shielding structure, and hole structure. The evaluation result differs according to the shielding material location. The dose rate was small when the shielding material was positioned at the center. The dose evaluation result regarding the location of the shielding material was applied to the facility and the shielding thickness was determined (In 50 cm + Borax 5 cm + Out 45cm). In the existing hole structure, the radiation leak is higher than the standard. A hole structure model to prevent leakage of radiation was proposed. The general public dose limit was satisfied when using the concrete reinforcement and a zigzag structure. The shielding result will be of help to the facility shielding optimization.

  19. Early Proterozoic palaeomagnetism: new results from the intrusives and related rocks of the Karelian, Belomorian and Kola provinces, eastern Fennoscandian Shield

    Science.gov (United States)

    Fedotova, M. A.; Khramov, A. N.; Pisakin, B. N.; Priyatkin, A. A.

    1999-06-01

    The palaeomagnetic data that are available for the eastern Fennoscandian Shield are too sparse to allow any palaeomagnetic constraints to be determined for intracratonic horizontal movements in this part of the shield. To address this issue we have obtained new palaeomagnetic data from mafic and ultramafic plutons, sills, dykes and basement country rocks in the Kola, Belomorian and Karelian provinces of the Fennoscandian Shield. A number of natural remanent magnetization (NRM) components were isolated, and we associate these with various events of Precambrian tectonomagmatic activity within the eastern Fennoscandian Shield. 36 palaeomagnetic poles were obtained. 12 poles, with ages ranging from 1700 Ma to 2450 Ma, satisfy the accepted reliability criteria (corresponding to the `B-category' of Briden & Duff 1981). Of these, six might be classified as reference poles. For the Kola and Belomorian provinces there are poles from the Main Range gabbro-dolerites (16.7 degS, 304.8 degE, A_95 =8.3 deg U-Pb age of 2436+/-25 Ma), the Voche-Lambina ultramafics and amphibolites (12.9 degN, 314.1 degE, A_95 =8.6 deg Rb-Sr age of 2198+/-172 Ma), and the Kolvitsa peridotites and schists (44.2 degN, 232.6 degE, A_95 =5.4 deg assigned magnetization age of 1900 Ma). For the Karelian Province, reference poles are presented for the Burakovka gabbro-norites (19.5 degS, 262.6 degE, A_95 =7.2 deg Sm-Nd age of 2439+/-22 Ma), the Matozero doleritic dykes (20.6 degS, 308.5 degE, A_95 =12.3 deg U-Pb age of 2150+/-60 Ma), and the Ropruchey Sill gabbro-dolerites (40.5 degN, 229.8 degE, A_95 =8.1 deg U-Pb age of 1770+/-12 Ma). Although some NRM components of other rocks are not as precisely dated, a number of palaeomagnetic poles are in good internal agreement, forming two tracks of the Lower Proterozoic apparent polar wander path (APWP). A preliminary version of the pre-Svecofennian APWP tracks for the Karelian and Kola-Belomorian provinces is proposed. Our results confirm the general drift

  20. Drip Shield Emplacement Gantry Concept

    Energy Technology Data Exchange (ETDEWEB)

    Silva, R.A.; Cron, J.

    2000-03-29

    This design analysis has shown that, on a conceptual level, the emplacement of drip shields is feasible with current technology and equipment. A plan for drip shield emplacement was presented using a Drip Shield Transporter, a Drip Shield Emplacement Gantry, a locomotive, and a Drip Shield Gantry Carrier. The use of a Drip Shield Emplacement Gantry as an emplacement concept results in a system that is simple, reliable, and interfaces with the numerous other exising repository systems. Using the Waste Emplacement/Retrieval System design as a basis for the drip shield emplacement concept proved to simplify the system by using existing equipment, such as the gantry carrier, locomotive, Electrical and Control systems, and many other systems, structures, and components. Restricted working envelopes for the Drip Shield Emplacement System require further consideration and must be addressed to show that the emplacement operations can be performed as the repository design evolves. Section 6.1 describes how the Drip Shield Emplacement System may use existing equipment. Depending on the length of time between the conclusion of waste emplacement and the commencement of drip shield emplacement, this equipment could include the locomotives, the gantry carrier, and the electrical, control, and rail systems. If the exisiting equipment is selected for use in the Drip Shield Emplacement System, then the length of time after the final stages of waste emplacement and start of drip shield emplacement may pose a concern for the life cycle of the system (e.g., reliability, maintainability, availability, etc.). Further investigation should be performed to consider the use of existing equipment for drip shield emplacement operations. Further investigation will also be needed regarding the interfaces and heat transfer and thermal effects aspects. The conceptual design also requires further design development. Although the findings of this analysis are accurate for the assumptions made

  1. Electronic Properties of Tin and Bismuth from Angular Correlation of Annihilation Photons

    DEFF Research Database (Denmark)

    Mogensen, O.E.; Trumpy, Georg

    1969-01-01

    ) deformed bismuth. For both metals, the single-crystal angular-correlation curves lie near to the free-electron parabola. The tin curves show more anisotropy than the bismuth curves. An important result is the clear anisotropy found in the high-momentum part of the curves—the tails—for both metals. Little...

  2. Solvothermal synthesis and study of nonlinear optical properties of nanocrystalline thallium doped bismuth telluride

    Energy Technology Data Exchange (ETDEWEB)

    Molli, Muralikrishna, E-mail: muralikrishnamolli@sssihl.edu.in [Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthinilayam-515 134 (India); Parola, Sowmendran; Avinash Chunduri, L.A.; Aditha, Saikiran; Sai Muthukumar, V; Mimani Rattan, Tanu; Kamisetti, Venkataramaniah [Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthinilayam-515 134 (India)

    2012-05-15

    Nanocrystalline Bismuth telluride and thallium (4 mol %) doped Bismuth telluride were synthesized through hydrothermal method. The as-prepared products were characterized using Powder X-ray Diffraction, High Resolution Transmission Electron Microscopy, Energy Dispersive X-Ray Spectroscopy, UV-Visible spectroscopy and Fourier Transform Infrared Spectroscopy. Powder XRD results revealed the crystalline nature of the obtained phases. HRTEM showed the particle-like morphology of the products. The decrease in the absorption coefficient due to thallium doping was observed in FTIR spectra. The intensity dependent nonlinear optical properties of nanocrystalline bismuth telluride and thallium doped bismuth telluride were studied using the Z-scan technique in open-aperture configuration. Bismuth telluride doped with thallium showed enhanced nonlinear optical response compared to pristine bismuth telluride and hence could be used as a potential candidate for optical power limiting applications. - Graphical Abstract: Nonlinear transmission (Z-scan) curves of nanocrystalline bismuth telluride ({Delta}) and thallium doped bismuth telluride ({open_square}). Thallium doped bismuth telluride showed enhanced nonlinear absorption compared to bismuth telluride. Inset: TEM micrograph of bismuth telluride nanocrystallites. Highlights: Black-Right-Pointing-Pointer Synthesis of Nanocrystalline Bi{sub 2}Te{sub 3} and Thallium doped Bi{sub 2}Te{sub 3} through solvothermal method. Black-Right-Pointing-Pointer Reduced absorption coefficient due to thallium doping found from IR spectroscopy. Black-Right-Pointing-Pointer Open-aperture Z-scan technique for nonlinear optical studies. Black-Right-Pointing-Pointer Two photon absorption based model for theoretical fitting of Z-scan data. Black-Right-Pointing-Pointer Enhanced nonlinear absorption in Thallium doped Bi{sub 2}Te{sub 3} - potential candidate for optical power limiting applications.

  3. Further analysis and evaluation of the results of the NATO common shield-DAT#7 experiment: defence against terrorism

    Science.gov (United States)

    Dill, Stephan; Peichl, Markus; Jirousek, Matthias; Süß, Helmut

    2009-09-01

    The contactless control of persons and the remote surveillance of sensitive infrastructures are important tasks in order to provide the required security measures to protect the human population against the threads of international terrorism. Passive microwave imaging allows a daytime independent observation and examination of objects and persons under nearly all adverse ambient conditions without artificial exposure, hence fully avoiding health risks. The penetration capability of microwaves provides the detection of objects through atmospheric obstacles like bad weather, fog or dust, vapour and smoke, as well as through thin non-metallic materials and clothing. For the latter the detection of hidden objects like weapons, explosives, and contraband is possible by monitoring dielectric anomalies. The experiment "Common Shield" is part of a perennial investigation series leaded by the "Center for Transformation of the German armed forces (Bundeswehr)". In 2008 the protection of soldiers and facilities was experimentally investigated under the aspect of a networked operational leadership. In this context as well a harbour protection trial was carried out in August/September 2008 at the naval base Eckernfoerde in Germany. This trial was part of the NATO CNADs program of work for "Defence Against Terrorism (DAT)" starting in 2003, and Germany is the lead nation for item 7 on "Technology for Intelligence, Surveillance, Reconnaissance & Target Acquisition of Terrorists (ISRTA)". One main activity in the Eckernfoerde trial was the simulation of a military entrance control facility by a tent including various imaging and a chemical sensor suite in order to provide security for a military camp. Besides commercial optical and infrared cameras various passive millimeter-wave imagers have been used from different German research institutions. The DLR Microwaves and Radar Institute, Department for Reconnaissance and Security (HR-AS), provided an imaging radiometer scanner

  4. Radiation Shielding Optimization on Mars

    Science.gov (United States)

    Slaba, Tony C.; Mertens, Chris J.; Blattnig, Steve R.

    2013-01-01

    Future space missions to Mars will require radiation shielding to be optimized for deep space transit and an extended stay on the surface. In deep space, increased shielding levels and material optimization will reduce the exposure from most solar particle events (SPE) but are less effective at shielding against galactic cosmic rays (GCR). On the surface, the shielding provided by the Martian atmosphere greatly reduces the exposure from most SPE, and long-term GCR exposure is a primary concern. Previous work has shown that in deep space, additional shielding of common materials such as aluminum or polyethylene does not significantly reduce the GCR exposure. In this work, it is shown that on the Martian surface, almost any amount of aluminum shielding increases exposure levels for humans. The increased exposure levels are attributed to neutron production in the shield and Martian regolith as well as the electromagnetic cascade induced in the Martian atmosphere. This result is significant for optimization of vehicle and shield designs intended for the surface of Mars.

  5. Controlled synthesis of bismuth oxyiodide toward optimization of photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Chenxing; Ma, Zhijun [State Key Laboratory of Luminescent Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510641 (China); Chen, Xiaofeng, E-mail: chenxf@scut.edu.c [Biomaterials Research Institute, School of Materials Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510641 (China); He, Xin [School of Applied Physics and Materials, Wuyi University, Jiangmen 529020 (China); Qiu, Jianrong, E-mail: qjr@scut.edu.cn [State Key Laboratory of Luminescent Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510641 (China)

    2016-11-30

    Highlights: • Different bismuth oxyiodide was synthesized. • The hollow Bi{sub 4}O{sub 5}I{sub 2} microspheres was obtained. • Formation mechanism of the hollow structure was discussed in detail. - Abstract: A new investigation on the variation rule of the structure, morphology, chemical composition and photocatalytic performance of bismuth oxyiodide synthesized by solvothermal method as a function of reaction conditions was performed here. The composition and morphology of the product could be determined by X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The results revealed that the particle size together with content of iodide in bismuth oxyiodide decrease with the increase of the concentration of reaction precursors. Hollow Bi{sub 4}O{sub 5}I{sub 2} microsphere with specific surface area as high as 120.88 m{sup 2} g{sup −1} can be easily synthesized when the concentration of the reaction precursors finally increased to 62.5 mM. Photocatalytic water purification performance of the as-prepared samples was evaluated by using Rhodamine B (RhB) as a model contaminant. The results revealed that the hollow Bi{sub 4}O{sub 5}I{sub 2} exhibited the best performance among all the bismuth oxyodide synthesized here for the degradation of RhB under visible light irradiation. Meanwhile, the formation mechanism of the hierarchical hollow structure of bismuth oxyiodide was investigated by the dissolution-recrystallization mechanism.

  6. Advanced Multifunctional MMOD Shield: Radiation Shielding Assessment

    Science.gov (United States)

    Rojdev, Kristina; Christiansen, Eric

    2013-01-01

    Deep space missions must contend with a harsh radiation environment Impacts to crew and electronics. Need to invest in multifunctionality for spacecraft optimization. MMOD shield. Goals: Increase radiation mitigation potential. Retain overall MMOD shielding performance.

  7. A new radiation shielding material: Amethyst ore

    Energy Technology Data Exchange (ETDEWEB)

    Korkut, Turgay, E-mail: turgaykorkut@hotmail.co [Faculty of Science and Art, Department of Physics, Ibrahim Cecen University, Agri (Turkey); Korkut, Hatun [Faculty of Science and Art, Department of Physics, Ibrahim Cecen University, Agri (Turkey); Karabulut, Abdulhalik; Budak, Goekhan [Faculty of Science, Department of Physics, Atatuerk University, Erzurum (Turkey)

    2011-01-15

    This paper describes a new radiation shielding material, amethyst ore. We have determined the elemental composition of amethyst using WDXRF spectroscopy technique. To see the shielding capability of amethyst for several photon energies, these results have been used in simulation process by FLUKA Monte Carlo radiation transport code. Linear attenuation coefficients have been calculated according to the simulation results. Then, these values have been compared to a fine shielding concrete material. The results show that amethyst shields more gamma beams than concrete. This investigation is the first study about the radiation shielding properties of amethyst ore.

  8. Inexpensive laser-induced surface modification in bismuth thin films

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, A. Reyes [Facultad de Ciencias, Universidad Autónoma del Estado de México, Carretera Toluca, Ixtlahuaca Kilómetro 15.5, C.P. 50200 Edo. de México (Mexico); Hautefeuille, M., E-mail: mathieu_h@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Exterior S/N, Coyoacán, Ciudad Universitaria, C.P. 04510 D.F. Mexico (Mexico); García, A. Esparza [Fotofísica y Películas Delgadas, Departamento de Tecnociencias, CCADET-UNAM, Circuito exterior s/n C.P. 04510 Cd. Universitaria, D.F. Mexico (Mexico); Mejia, O. Olea [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, Km 14.5, Unidad El Rosedal, 50200 San Cayetano, Estado de México (Mexico); López, M.A. Camacho [Facultad de Química, Universidad Autónoma del Estado de México, Tollocan s/n, esq. Paseo Colón, Toluca, Estado de México 50110 (Mexico)

    2015-05-01

    Highlights: • Laser-induced microbumps were formed on bismuth films using a simple, low-cost, laser setup. • The patterns, similar to those typically obtained with high-power lasers, were characterized. • Control of laser ablation conditions is critical in the fabrication of surface microbumps. - Abstract: In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD–DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters.

  9. Compact and Integrated Liquid Bismuth Propellant Feed System

    Science.gov (United States)

    Polzin, Kurt A.; Stanojev, Boris; Korman, Valentin; Gross, Jeffrey T.

    2007-01-01

    Operation of Hall thrusters with bismuth propellant has been shown to be a promising path toward high-power, high-performance, long-lifetime electric propulsion for spaceflight missions [1]. There has been considerable effort in the past three years aimed at resuscitating this promising technology and validating earlier experimental results indicating the advantages of a bismuth-fed Hall thruster. A critical element of the present effort is the precise metering of propellant to the thruster, since performance cannot be accurately assessed without an accurate accounting of mass flow rate. Earlier work used a pre./post-test propellant weighing scheme that did not provide any real-time measurement of mass flow rate while the thruster was firing, and makes subsequent performance calculations difficult. The motivation of the present work is to develop a precision liquid bismuth Propellant Management System (PMS) that provides hot, molten bismuth to the thruster while simultaneously monitoring in real-time the propellant mass flow rate. The system is a derivative of our previous propellant feed system [2], but the present system represents a more compact design. In addition, all control electronics are integrated into a single unit and designed to reside on a thrust stand and operate in the relevant vacuum environment where the thruster is operating, significantly increasing the present technology readiness level of liquid metal propellant feed systems. The design of various critical components in a bismuth PMS are described. These include the bismuth reservoir and pressurization system, 'hotspot' flow sensor, power system and integrated control system. Particular emphasis is given to selection of the electronics employed in this system and the methods that were used to isolate the power and control systems from the high-temperature portions of the feed system and thruster. Open loop calibration test results from the 'hotspot' flow sensor are reported, and results of

  10. Exhaustive removal of chloride ions from water with the aid of a bismuth-based metallic sorbent

    Energy Technology Data Exchange (ETDEWEB)

    Moskvin, L.N.; Ushenko, V.G.

    1988-04-20

    The authors discuss the sorption properties of sorbents based on metallic bismuth, in relation to a solution of the problem of exhaustive removal of chloride ions from water. Metallic sorbents with bismuth contents of 10 mass % on polytetrafluoroethylene were used. The sorption properties of sorbents based on metallic bismuth and on Bi/sub 2/O/sub 3/ were studied under dynamic conditions. Their results show that bismuth-based metal sorbents and sorbents based on bismuth oxide can be used as inorganic anion-exchangers. In order to demonstrate the possibility of selective separation of chloride ions from solutions they determined the dynamic exchange capacity for chloride ions at various nitrate-ion concentrations. The use of the proposed sorbents based on metallic bismuth for exhaustive purification of water lowers the chloride-ion concentration in the water sharply in comparison with the level achieved by ion-exchange purification with the aid of organic anion-exchangers.

  11. Effects of Breast Shielding during Heart Imaging on DNA Double-Strand-Break Levels: A Prospective Randomized Controlled Trial.

    Science.gov (United States)

    Cheezum, Michael K; Redon, Christophe E; Burrell, Allison S; Kaviratne, Anthony S; Bindeman, Jody; Maeda, Daisuke; Balmakhtar, Houria; Pezel, Ashly; Wisniewski, Piotr; Delacruz, Panfilo; Nguyen, Binh; Bonner, William M; Villines, Todd C

    2016-10-01

    Purpose To examine the effect of breast shielding on blood lymphocyte deoxyribonucleic acid (DNA) double-strand-break levels resulting from in vivo radiation and ex vivo radiation at breast-tissue level, and the effect of breast shielding on image quality. Materials and Methods The study was approved by institutional review and commpliant with HIPAA guidelines. Adult women who underwent 64-section coronary computed tomographic (CT) angiography and who provided informed consent were prospectively randomized to the use (n = 50) or absence (n = 51) of bismuth breast shields. Peripheral blood samples were obtained before and 30 minutes after in vivo radiation during CT angiography to compare DNA double-strand-break levels by γ-H2AX immunofluorescence in blood lymphocytes. To estimate DNA double-strand-break induction at breast-tissue level, a blood sample was taped to the sternum for ex vivo radiation with or without shielding. Data were analyzed by linear regression and independent sample t tests. Results Breast shielding had no effect on DNA double-strand-break levels from ex vivo radiation of blood samples under shields at breast-tissue level (unadjusted regression: β = .08; P = .43 versus no shielding), or in vivo radiation of circulating lymphocytes (β = -.07; P = .50). Predictors of increased DNA double-strand-break levels included total radiation dose, increasing tube potential, and tube current (P radiation exposures (median, 3.4 mSv), breast shielding yielded a 33% increase in image noise and 19% decrease in the rate of excellent quality ratings. Conclusion Among women who underwent coronary CT angiography, breast shielding had no effect on DNA double-strand-break levels in blood lymphocytes exposed to in vivo radiation, or ex vivo radiation at breast-tissue level. At present relatively low radiation exposures, breast shielding contributed to an increase in image noise and a decline in image quality. The findings support efforts to minimize radiation by

  12. Microscopic and voltammetric properties of lustrous bismuth deposits

    OpenAIRE

    Krolicka, Agnieszka; Bobrowski, Andrzej; Pamuła, Elżbieta

    2010-01-01

    A comparison of lustrous bismuth films, plated at glassy carbon, platinum and gold supports, is presented. The voltammetric performance of preplated bismuth film electrodes was tested using 50 μg/L In(III) and 50 μg/L Pb(II) solutions in 0.1 M acetic buffer in square wave and differential pulse modes. The influence of support material, plating solution concentration and storing conditions on the voltammetric response of BiFEs is discussed. The results of microscopic examination...

  13. New Materials for EMI Shielding

    Science.gov (United States)

    Gaier, James R.

    1999-01-01

    Graphite fibers intercalated with bromine or similar mixed halogen compounds have substantially lower resistivity than their pristine counterparts, and thus should exhibit higher shielding effectiveness against electromagnetic interference. The mechanical and thermal properties are nearly unaffected, and the shielding of high energy x-rays and gamma rays is substantially increased. Characterization of the resistivity of the composite materials is subtle, but it is clear that the composite resistivity is substantially lowered. Shielding effectiveness calculations utilizing a simple rule of mixtures model yields results that are consistent with available data on these materials.

  14. Optical Properties of Bismuth Tellurite Based Glass

    Directory of Open Access Journals (Sweden)

    Hooi Ming Oo

    2012-04-01

    Full Text Available A series of binary tellurite based glasses (Bi2O3x (TeO2100−x was prepared by melt quenching method. The density, molar volume and refractive index increase when bismuth ions Bi3+ increase, this is due to the increased polarization of the ions Bi3+ and the enhanced formation of non-bridging oxygen (NBO. The Fourier transform infrared spectroscopy (FTIR results show the bonding of the glass sample and the optical band gap, Eopt decreases while the refractive index increases when the ion Bi3+ content increases.

  15. Optical properties of bismuth tellurite based glass.

    Science.gov (United States)

    Oo, Hooi Ming; Mohamed-Kamari, Halimah; Wan-Yusoff, Wan Mohd Daud

    2012-01-01

    A series of binary tellurite based glasses (Bi(2)O(3))(x) (TeO(2))(100-) (x) was prepared by melt quenching method. The density, molar volume and refractive index increase when bismuth ions Bi(3+) increase, this is due to the increased polarization of the ions Bi(3+) and the enhanced formation of non-bridging oxygen (NBO). The Fourier transform infrared spectroscopy (FTIR) results show the bonding of the glass sample and the optical band gap, E(opt) decreases while the refractive index increases when the ion Bi(3+) content increases.

  16. Shielding properties of lead-free protective clothing and their impact on radiation doses.

    Science.gov (United States)

    Schlattl, Helmut; Zankl, Maria; Eder, Heinrich; Hoeschen, Christoph

    2007-11-01

    The shielding properties of two different lead-free materials-tin and a compound of 80% tin and 20% bismuth-for protective clothing are compared with those of lead for three typical x-ray spectra generated at tube voltages of 60, 75, and 120 kV. Three different quantities were used to compare the shielding capability of the different materials: (1) Air-kerma attenuation factors in narrow-beam geometry, (2) air-kerma attenuation factors in broad-beam geometry, and (3) ratios of organ and effective doses in the human body for a whole-body irradiation with a parallel beam directed frontally at the body. The thicknesses of tin (0.45 mm) and the tin/bismuth compound (0.41 mm) to be compared against lead correspond to a lead equivalence value of 0.35 mm for the 75 kV spectrum. The narrow-beam attenuation factors for 0.45 mm tin are 54% and 32% lower than those for 0.35 mm lead for 60 and 120 kV; those for 0.41 mm tin/bismuth are 12% and 32% lower, respectively. The decrease of the broad-beam air-kerma attenuation factors compared to lead is 74%, 46%, and 41% for tin and 42%, 26%, and 33% for tin/bismuth and the spectra at 60, 75, and 120 kV, respectively. Therefore, it is recommended that the characterization of the shielding potential of a material should be done by measurements in broad-beam geometry. Since the secondary radiation that is mainly responsible for the shielding reduction in broad-beam geometry is of low penetrability, only more superficially located organs receive significantly enhanced doses. The increase for the dose to the glandular breast tissue (female) compared to being shielded by lead is 143%, 37%, and 45% when shielded by tin, and 35%, 15%, and 39% when shielded by tin/bismuth for 60, 75, and 120 kV, respectively. The effective dose rises by 60%, 6%, and 38% for tin, and 14%, 3% and, 35% for tin/bismuth shielding, respectively.

  17. Comparative Study of Semiconductors Bismuth Iodate, Bismuth Triiodide and Bismuth Trisulphide Crystals

    Directory of Open Access Journals (Sweden)

    T.K. Patil

    2012-12-01

    Full Text Available In the present investigation, crystals of Bismuth Iodate[Bi(IO33], Bismuth Iodide[BiI3] and Bismuth- Tri Sulphide [Bi2S3] were grown by a simple gel technique using single diffusion method. The optimum growth conditions were established by varying various parameters such as pH of gel solution, gel concentration, gel setting time, concentration of reactant etc. Gel was prepared by mixing sodium meta silicate (Na2SiO35H2O, glacial acetic acid (CH3COOH and supernant bismuth chloride (BiCl3 at pH value 4.4 and transferred in glass tube of diameter 2.5 cm and 25 cm in length. The mouth of test tube was covered by cotton plug and kept it for the setting. After setting the gel, it was left for aging. After 13 days duration the second supernant K(IO3, KI3 and H2S water gas solution was poured over the set gel by using pipette then it was kept undisturbed. After 72 hours of pouring the second supernatant, the small nucleation growth was observed at below the interface of gel. The good quality crystals of [Bi(IO33], [BiI3] and [Bi2S3] were grown. These grown crystals were characterized by XRD, FTIR, Chemical Analysis and Electrical Conductivity.

  18. Light-Induced Absorption in Nominally Pure Bismuth Silicon Oxide

    Institute of Scientific and Technical Information of China (English)

    李飞飞; 许京军; 孔勇发; 黄辉; 张光寅; 杨春晖; 徐玉恒

    2001-01-01

    Light-induced absorption in the nominally pure bismuth silicon oxide is investigated experimentally and the result shows that it consists of transient and persistent parts. The experimental evidence is analysed based on the model of three groups of trap (donor) centres.

  19. Corrugation Stuffed Shield for Spacecraft and Its Performance

    Institute of Scientific and Technical Information of China (English)

    LIU You-ying; WANG Hai-fu

    2006-01-01

    A corrugation stuffed shield system protecting spacecrafts against meteoroid and orbital debris (M/OD) is presented. The semi-empirical ballistic limit equations (BLEs)defining the protection capability of the shield system are given, an d the shielding performance is also discussed. The corrugation stuffed shield (CSS) is more effective than stuffed Whipple shield for M/OD protection,and its shielding performance will be improved significantly as increasing the impact angle. Orbital debris up to 1cm in diameter can be shielded effectively as increasing the impact angle to 25° at the corrugated angle of 30°. The results are significant to spacecraft design.

  20. Hydrothermal synthesis of bismuth germanium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, Timothy J.

    2016-12-13

    A method for the hydrothermal synthesis of bismuth germanium oxide comprises dissolving a bismuth precursor (e.g., bismuth nitrate pentahydrate) and a germanium precursor (e.g., germanium dioxide) in water and heating the aqueous solution to an elevated reaction temperature for a length of time sufficient to produce the eulytite phase of bismuth germanium oxide (E-BGO) with high yield. The E-BGO produced can be used as a scintillator material. For example, the air stability and radioluminescence response suggest that the E-BGO can be employed for medical applications.

  1. Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2014-01-01

    We propose new designs of plasmonic modulators, which can beused for dynamic signal switching in photonic integrated circuits. We studyperformance of a plasmonic waveguide modulator with bismuth ferrite as atunable material. The bismuth ferrite core is sandwiched between metalplates (metal-insulator......-metal configuration), which also serve as electrodes.The core changes its refractive index by means of partial in-plane to out-of-plane reorientation of ferroelectric domains in bismuth ferrite under appliedvoltage. As a result, guided modes change their propagation constant andabsorption coefficient, allowing light...

  2. Is the ultra-fast transformation of bismuth non-thermal?

    CERN Document Server

    Gamaly, E G

    2009-01-01

    Transient state of femtosecond laser excited bismuth has been studied by various groups with time-resolved optical, x-ray, and electron probes at the deposited energy density from below through up to several times the equilibrium enthalpy of melting. However, the interpretations of the experimental results are controversial: the optical probes reveal the absence of transition to the melting phase while the authors of x-ray and electron diffraction experiments claim the observation of ultrafast non-thermal melting. The presented analysis, based on temperature dependence of bismuth optical properties, unequivocally shows a purely thermal nature of all the observed fs-laser induced transformations in bismuth.

  3. Oxidation mechanism of formic acid on the bismuth adatom-modified Pt(111) surface.

    Science.gov (United States)

    Perales-Rondón, Juan Victor; Ferre-Vilaplana, Adolfo; Feliu, Juan M; Herrero, Enrique

    2014-09-24

    In order to improve catalytic processes, elucidation of reaction mechanisms is essential. Here, supported by a combination of experimental and computational results, the oxidation mechanism of formic acid on Pt(111) electrodes modified by the incorporation of bismuth adatoms is revealed. In the proposed model, formic acid is first physisorbed on bismuth and then deprotonated and chemisorbed in formate form, also on bismuth, from which configuration the C-H bond is cleaved, on a neighbor Pt site, yielding CO2. It was found computationally that the activation energy for the C-H bond cleavage step is negligible, which was also verified experimentally.

  4. Bismuth absorption from sup 205 Bi-labelled pharmaceutical bismuth compounds used in the treatment of peptic ulcer disease

    Energy Technology Data Exchange (ETDEWEB)

    Dresow, B.; Fischer, R.; Gabbe, E.E.; Wendel, J.; Heinrich, H.C. (Eppendorf University Hospital, Hamburg (Germany))

    1992-04-01

    The absorption of bismuth from five {sup 205}Bi-labelled pharmaceutically used bismuth compounds was studied in man. From single oral doses of all compounds under investigation only <0.1% bismuth was absorbed and excreted with the urine. A significantly higher absorption was observed from the colloidal bismuth subcitrate and the basic bismuth gallate than from the basic bismuth salicylate, nitrate and aluminate. No retention of bismuth in the whole body was found from the single dose experiment. The biologic fast-term half-lives of absorbed bismuth were calculated to be 0.12 and 1.5 days. 14 refs., 2 figs., 1 tab.

  5. Ranitidine bismuth citrate: A review

    Directory of Open Access Journals (Sweden)

    N Chiba

    2001-01-01

    Full Text Available Recognition of the relationship between Helicobacter pylori infection and the development of gastroduodenal disease has increased greatly in recent years. To avoid complications of H pylori infection, such as the development of recurrent duodenal and gastric ulcers, effective therapies are required for eradication of the infection. This article reviews ranitidine bismuth citrate (RBC, a novel complex of ranitidine, bismuth and citrate, which was developed specifically for the purpose of eradicating H pylori. Dual therapy with RBC in combination with clarithromycin for 14 days yields eradication rates of 76%. Triple therapy bid for one week with a proton pump inhibitor, clarithromycin and either amoxicillin or a nitroimidazole (tinidazole or metronidazole is advocated as the treatment of choice for H pylori eradication. Analogous regimens with RBC in place of proton pump inhibitors show effective eradication rates in comparative studies and with pooled data. RBC, used alone or in combination with other antibiotics, appears to be a safe and effective drug for the treatment of H pylori infection. Bismuth levels do not appear to rise to toxic levels.

  6. The Feasibility of Multipole Electrostatic Radiation Shielding

    Science.gov (United States)

    Metzger, Philip T.; Lane, John E.; Youngquist, Robert C.

    2004-01-01

    Although passive shielding appears to be the only workable solution for galactic cosmic radiation (GCR), active shielding may play an important augmenting role to control the dose from solar particle events (SPEs). It has been noted that, to meet the guidelines of NCRP Report No. 98 through the six SPEs of 1989, a crew member would need roughly double the passive shielding that is necessary to control the GCR dose . This would dramatically increase spacecraft mass, and so it has been proposed that a small but more heavily shielded storm shelter may be used to protect the crew during SPEs. Since a gradual SPE may last 5 or more days, staying in a storm shelter may be psychologically and physiologically distressing to the crew. Storm shelters do not provide shielding for the spacecraft itself against the SPE radiation, and radiation damage to critical electronics may result in loss of mission and life. Single-event effects during the radiation storm may require quick crew response to maintain the integrity of the spacecraft, and confining the crew to a storm shelter prohibits their attending to the spacecraft at the precise time when that attention is needed the most. Active shielding cannot protect against GCR because the particle energies are too high. Although lower energy particles are easier to stop in a passive shield, such shielding is more satisfactory against GCR than against SPE radiation because of the tremendous difference in their initial fluences. Even a small fraction of the SPE fluence penetrating the passive shielding may result in an unacceptably high dose. Active shielding is more effective than passive shielding against SPE radiation because it offers 100% shielding effectiveness up to the cutoff energy, and significant shielding effectiveness beyond the cutoff as well.

  7. Magnetic and Electrical Characteristics of Bismuth Ferrite, Depending on the Impurities, Method of Preparation and Size of the Nanoparticles

    Directory of Open Access Journals (Sweden)

    V.M. Sarnatsky

    2016-10-01

    Full Text Available The prospect of application of the multiferroics in devices and spintronics devices is shown. A comparative analysis of magnetic and dielectric properties of nanostructures based on bismuth ferrite which were synthesized by various ways was made. The results of studies of the structure and properties of the nanostructured bismuth ferrite powder, synthesized by combustion of nitrate - organic precursors, are presented.

  8. Bismuth-based oxide semiconductors: Mild synthesis and practical applications

    Science.gov (United States)

    Timmaji, Hari Krishna

    In this dissertation study, bismuth based oxide semiconductors were prepared using 'mild' synthesis techniques---electrodeposition and solution combustion synthesis. Potential environmental remediation and solar energy applications of the prepared oxides were evaluated. Bismuth vanadate (BiVO4) was prepared by electrodeposition and solution combustion synthesis. A two step electrosynthesis strategy was developed and demonstrated for the first time. In the first step, a Bi film was first electrodeposited on a Pt substrate from an acidic BiCl3 medium. Then, this film was anodically stripped in a medium containing hydrolyzed vanadium precursor, to generate Bi3+, and subsequent BiVO4 formation by in situ precipitation. The photoelectrochemical data were consistent with the in situ formation of n-type semiconductor films. In the solution combustion synthesis procedure, BiVO4 powders were prepared using bismuth nitrate pentahydrate as the bismuth precursor and either vanadium chloride or vanadium oxysulfate as the vanadium precursor. Urea, glycine, or citric acid was used as the fuel. The effect of the vanadium precursor on the photocatalytic activity of combustion synthesized BiVO 4 was evaluated in this study. Methyl orange was used as a probe to test the photocatalytic attributes of the combustion synthesized (CS) samples, and benchmarked against a commercial bismuth vanadate sample. The CS samples showed superior activity to the commercial benchmark sample, and samples derived from vanadium chloride were superior to vanadium oxysulfate counterparts. The photoelectrochemical properties of the various CS samples were also studied and these samples were shown to be useful both for environmental photocatalytic remediation and water photooxidation applications. Silver bismuth tungstate (AgBiW2O8) nanoparticles were prepared for the first time by solution combustion synthesis by using silver nitrate, bismuth nitrate, sodium tungstate as precursors for Ag, Bi, and W

  9. Radiation shielding concrete made of Basalt aggregates.

    Science.gov (United States)

    Alhajali, S; Yousef, S; Kanbour, M; Naoum, B

    2013-04-01

    In spite of the fact that Basalt is a widespread type of rock, there is very little available information on using it as aggregates for concrete radiation shielding. This paper investigates the possibility of using Basalt for the aforementioned purpose. The results have shown that Basalt could be used successfully for preparing radiation shielding concrete, but some attention should be paid to the choice of the suitable types of Basalt and for the neutron activation problem that could arise in the concrete shield.

  10. The Active Muon Shield

    CERN Document Server

    Bezshyiko, Iaroslava

    2016-01-01

    In the SHiP beam-dump of the order of 1011 muons will be produced per second. An active muon-shield is used to magnetically deflect these muons out of the acceptance of the spectrom- eter. This note describes how this shield is modelled and optimized. The SHiP spectrometer is being re-optimized using a conical decay-vessel, and utilizing the possibility to magnetize part of the beam-dump shielding iron. A shield adapted to these new conditions is presented which is significantly shorter and lighter than the shield used in the Technical Proposal (TP), while showing a similar performance.

  11. Watching a disappearing shield

    Science.gov (United States)

    Stolarski, Richard S.

    1988-10-01

    The remote-sensing techniques used to monitor atmospheric ozone levels are reviewed, and recent results are discussed. The importance of the ozone layer as a shield for UV radiation is stressed, and the impact of human activities generating ozone-destroying compounds is considered. Ground-based, airborne, balloon-borne, and satellite remote-sensing methods are shown to complement each other to provide both global coverage and detailed structural information. Data obtained with the Nimbus-7 TOMS and solar-backscatter UV instruments are presented in graphs and briefly characterized.

  12. Microwave-assisted synthesis of bismuth oxide

    Directory of Open Access Journals (Sweden)

    Eva Bartonickova

    2007-12-01

    Full Text Available Single phase and ultrafine bismuth oxide was synthesized via microwave-assisted hydrothermal synthesis. The effect of reaction parameters (temperature/pressure and pH on the product phase composition and morphology was discussed. The transformation of bismuth hydroxide into bismuth oxide was controlled by pH value and it was accelerated by time and temperature. The phase composition of reaction products was strongly dependent on pH value. The amorphous products were obtained at acidic pH conditions and the crystalline single phase product α-Bi2O3 phase was obtained at pH ≥12. The particle size was reduced from micrometric to nanometric size in the presence of a chelating agent. The bismuth hydroxides into bismuth oxides transformation mechanism, consisting in polycondensation ofBi–OH bounds to Bi–O–Bi bridges and crystallization of Bi2O3, was proposed.

  13. Zerovalent bismuth nanoparticles inhibit Streptococcus mutans growth and formation of biofilm

    Science.gov (United States)

    Hernandez-Delgadillo, Rene; Velasco-Arias, Donaji; Diaz, David; Arevalo-Niño, Katiushka; Garza-Enriquez, Marianela; De la Garza-Ramos, Myriam A; Cabral-Romero, Claudio

    2012-01-01

    Background and methods Despite continuous efforts, the increasing prevalence of resistance among pathogenic bacteria to common antibiotics has become one of the most significant concerns in modern medicine. Nanostructured materials are used in many fields, including biological sciences and medicine. While some bismuth derivatives has been used in medicine to treat vomiting, nausea, diarrhea, and stomach pain, the biocidal activity of zerovalent bismuth nanoparticles has not yet been studied. The objective of this investigation was to analyze the antimicrobial activity of bismuth nanoparticles against oral bacteria and their antibiofilm capabilities. Results Our results showed that stable colloidal bismuth nanoparticles had 69% antimicrobial activity against Streptococcus mutans growth and achieved complete inhibition of biofilm formation. These results are similar to those obtained with chlorhexidine, the most commonly used oral antiseptic agent. The minimal inhibitory concentration of bismuth nanoparticles that interfered with S. mutans growth was 0.5 mM. Conclusion These results suggest that zerovalent bismuth nanoparticles could be an interesting antimicrobial agent to be incorporated into an oral antiseptic preparation. PMID:22619547

  14. Overview of the use of ATHENA for thermal-hydraulic analysis of systems with lead-bismuth coolant

    Energy Technology Data Exchange (ETDEWEB)

    C. B. Davis; A. S. Shieh

    2000-04-02

    The INEEL and MIT are investigating the suitability of lead-bismuth cooled fast reactor for producing low-cost electricity as well as for actinide burning. This paper is concerned with the general area of thermal-hydraulics of lead-bismuth cooled reactors. The ATHENA code is being used in the thermal-hydraulic design and analysis of lead-bismuth cooled reactors. The ATHENA code was reviewed to determine its applicability for simulating lead-bismuth cooled reactors. Two modifications were made to the code as a result of this review. Specifically, a correlation to represent heat transfer from rod bundles to a liquid metal and a void correlation based on data taken in a mixture of lead-bismuth and steam were added the code. The paper also summarizes the analytical work that is being performed with the code and plans for future analytical work.

  15. Overview of the Use of ATHENA for Thermal-Hydraulic Analysis of Systems with Lead-Bismuth Coolant

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Cliff Bybee; Shieh, Arthur Shan Luk

    2000-04-01

    The INEEL and MIT are investigating the suitability of lead-bismuth cooled fast reactor for producing low-cost electricity as well as for actinide burning. This paper is concerned with the general area of thermal-hydraulics of lead-bismuth cooled reactors. The ATHENA code is being used in the thermal-hydraulic design and analysis of lead-bismuth cooled reactors. The ATHENA code was reviewed to determine its applicability for simulating lead-bismuth cooled reactors. Two modifications were made to the code as a result of this review. Specifically, a correlation to represent heat transfer from rod bundles to a liquid metal and a void correlation based on data taken in a mixture of lead-bismuth and steam were added the code. The paper also summarizes the analytical work that is being performed with the code and plans for future analytical work.

  16. Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

    Science.gov (United States)

    Ratova, Marina; Kelly, Peter J.; West, Glen T.; Tosheva, Lubomira; Edge, Michele

    2017-01-01

    Titanium dioxide - bismuth tungstate composite materials were prepared by pulsed DC reactive magnetron sputtering of bismuth and tungsten metallic targets in argon/oxygen atmosphere onto anatase and rutile titania nanoparticles. The use of an oscillating bowl placed beneath the two magnetrons arranged in a co-planar closed field configuration enabled the deposition of bismuth tungstate onto loose powders, rather than a solid substrate. The atomic ratio of the bismuth/tungsten coatings was controlled by varying the power applied to each target. The effect of the bismuth tungstate coatings on the phase, optical and photocatalytic properties of titania was investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area measurements, transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy and an acetone degradation test. The latter involved measurements of the rate of CO2 evolution under visible light irradiation of the photocatalysts, which indicated that the deposition of bismuth tungstate resulted in a significant enhancement of visible light activity, for both anatase and rutile titania particles. The best results were achieved for coatings with a bismuth to tungsten atomic ratio of 2:1. In addition, the mechanism by which the photocatalytic activity of the TiO2 nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these tests confirmed that such enhancement of the photocatalytic properties is due to more efficient photogenerated charge carrier separation, as well as to the contribution of the intrinsic photocatalytic properties of Bi2WO6.

  17. Study of mass attenuation coefficients and effective atomic numbers of bismuth-ground granulated blast furnace slag concretes

    Science.gov (United States)

    Kumar, Sandeep; Singh, Sukhpal

    2016-05-01

    Five samples of Bismuth-Ground granulated blast furnace slag (Bi-GGBFS) concretes were prepared using composition (0.6 cement + x Bi2O3 + (0.4-x) GGBFS, x = 0.05, 0.10, 0.15, 0.20 and 0.25) by keeping constant water (W) cement (C) ratio. Mass attenuation coefficients (μm) of these prepared samples were calculated using a computer program winXCOM at different gamma ray energies, whereas effective atomic numbers (Zeff) is calculated using mathematical formulas. The radiation shielding properties of Bi-GGBFS concrete has been compared with standard radiation shielding concretes.

  18. Validation of PHITS Spallation Models from the Perspective of the Shielding Design of Transmutation Experimental Facility

    Science.gov (United States)

    Iwamoto, Hiroki; Meigo, Shin-ichiro

    2017-09-01

    The impact of different spallation models implemented in the particle transport code PHITS on the shielding design of Transmutation Experimental Facility is investigated. For 400-MeV proton incident on a lead-bismuth eutectic target, an effective dose rate at the end of a thick radiation shield (3-m-thick iron and 3-m-thick concrete) calculated by the Liège intranuclear cascade (INC) model version 4.6 (INCL4.6) coupled with the GEMcode (INCL4.6/GEM) yields about twice as high as the Bertini INC model (Bertini/GEM). A comparison with experimental data for 500-MeV proton incident on a thick lead target suggest that the prediction accuracy of INCL4.6/GEM would be better than that of Bertini/GEM. In contrast, it is found that the dose rates in beam ducts in front of targets calculated by the INCL4.6/GEMare lower than those by the Bertini/GEM. Since both models underestimate the experimental results for neutron-production doubledifferential cross sections at 180° for 140-MeV proton incident on carbon, iron, and gold targets, it is concluded that it is necessary to allow a margin for uncertainty caused by the spallation models, which is a factor of two, in estimating the dose rate induced by neutron streaming through a beam duct.

  19. Validation of PHITS Spallation Models from the Perspective of the Shielding Design of Transmutation Experimental Facility

    Directory of Open Access Journals (Sweden)

    Iwamoto Hiroki

    2017-01-01

    Full Text Available The impact of different spallation models implemented in the particle transport code PHITS on the shielding design of Transmutation Experimental Facility is investigated. For 400-MeV proton incident on a lead-bismuth eutectic target, an effective dose rate at the end of a thick radiation shield (3-m-thick iron and 3-m-thick concrete calculated by the Liège intranuclear cascade (INC model version 4.6 (INCL4.6 coupled with the GEMcode (INCL4.6/GEM yields about twice as high as the Bertini INC model (Bertini/GEM. A comparison with experimental data for 500-MeV proton incident on a thick lead target suggest that the prediction accuracy of INCL4.6/GEM would be better than that of Bertini/GEM. In contrast, it is found that the dose rates in beam ducts in front of targets calculated by the INCL4.6/GEMare lower than those by the Bertini/GEM. Since both models underestimate the experimental results for neutron-production doubledifferential cross sections at 180◦ for 140-MeV proton incident on carbon, iron, and gold targets, it is concluded that it is necessary to allow a margin for uncertainty caused by the spallation models, which is a factor of two, in estimating the dose rate induced by neutron streaming through a beam duct.

  20. Bismuth ions are metabolized into autometallographic traceable bismuth-sulphur quantum dots

    Directory of Open Access Journals (Sweden)

    M Stoltenberg

    2009-06-01

    Full Text Available Bismuth – sulphur quantum dots can be silver enhanced by autometallography (AMG. In the present study, autometallographic silver enhanced bismuth-sulphur nanocrystals were isolated from unfixed cryo-sections of kidneys and livers of rats exposed to bismuth (Bi207 subnitrate. After being subjected to AMG all the organic material was removed by sonication and enzymatic digestion and the silver enhanced Bi- S quantum dots spun down by an ultracentrifuge and analyzed by scintillation. The analysis showed that the autometallographic technique traces approximately 94% of the total bismuth. This implies that the injected bismuth is ultimately captured in bismuthsulphur quantum dots, i.e., that Bi-S nanocrystals are the end product of bismuth metabolism

  1. Adverse events with bismuth salts for Helicobacter pylori eradication:Systematic review and meta-analysis

    Institute of Scientific and Technical Information of China (English)

    Alexander C Ford; Peter Malfertheiner; Monique Giguére; José Santana; Mostafizur Khan; Paul Moayyedi

    2008-01-01

    AIM:To assess the safety of bismuth used in Helicobacter pylori (H pylori) eradication therapy regimens.METHODS:We conducted a systematic review and meta-analysis.MEDLINE and EMBASE were searched (up to October 2007) to identify randomised controlled trials comparing bismuth with placebo or no treatment,or bismuth salts in combination with antibiotics as part of eradication therapy with the same dose and duration of antibiotics alone or,in combination,with acid suppression.Total numbers of adverse events were recorded.Data were pooled and expressed as relative risks with 95% confidence intervals (CI).RESULTS:We identified 35 randomised controlled trials containing 4763 patients.There were no serious adverse events occurring with bismuth therapy.There was no statistically significant difference detected in total adverse events with bismuth [relative risk (RR)=1.01;95% CI:0.87-1.16],specific individual adverse events,with the exception of dark stools (RR = 5.06;95% CI:1.59-16.12),or adverse events leading to withdrawal of therapy (RR = 0.86;95% CI:0.54-1.37).CONCLUSION:Bismuth for the treatment of H pylori is safe and well-tolerated.The only adverse event occurring significantly more commonly was dark stools.

  2. Wine as a digestive aid: comparative antimicrobial effects of bismuth salicylate and red and white wine.

    Science.gov (United States)

    Weisse, M. E.; Eberly, B.; Person, D. A.

    1995-01-01

    OBJECTIVE--To test whether red and white wines are as potent as bismuth salicylate against the bacteria responsible for traveller's diarrhoea to try to explain wine's legendary reputation as a digestive aid. DESIGN--Red and white wine, bismuth salicylate, two solutions containing ethanol (diluted absolute ethanol and tequila), and sterilised water were tested against suspensions of salmonella, shigella, and Escherichia coli to determine relative antibacterial activity. Suspensions of 10(7) colony forming units of shigella, salmonella, and E coli were added to the test solutions and plated on standard nutrient agar at 0, 10, 20, 30, 60, and 120 minutes and 24 hours. Dilutions of wine and bismuth salicylate were then tested with E coli as the test bacterium, and the experiment repeated. MAIN OUTCOME MEASURES--Exposure times necessary for eradication of organisms for the different solutions; decreases in colony counts at the different exposure times for dilutions of wine and bismuth salicylates. RESULTS--Undiluted wine and bismuth salicylate were both effective in reducing the number of viable organisms (by 10(5)-10(6) colony forming units) after 20-30 minutes. Dilutions of wine were much more effective in decreasing colony counts than were similar dilutions of bismuth salicylate. CONCLUSION--The antibacterial property of wine is largely responsible for wine's reputation as a digestive aid. Images p1659-a PMID:8541747

  3. Preparation of Strontium Bismuth Tantalum (SBT) Fine Powder by Sol-Gel Process Using Bismuth Subnitrate as Bismuth Source

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Strontium bismuth tantalum (SBT) fine power was prepared by Sol-Gel method. Pentaethoxy tantalum, strontium acetate and bismuth subnitrate were used as raw materials, and were dissolved in proper order in ethylene glycol to form transparent sol. The mixed precursor was dried at 80°C and annealed at 800°C for 1 h. Crystallized nanometer sized SBT fine powder was obtained and characterized by XRD.

  4. Photoreductive generation of amorphous bismuth nanoparticles using polysaccharides--bismuth-cellulose nanocomposites.

    Science.gov (United States)

    Breitwieser, Doris; Kriechbaum, Margit; Ehmann, Heike M A; Monkowius, Uwe; Coseri, Sergiu; Sacarescu, Liviu; Spirk, Stefan

    2015-02-13

    A simple and highly reproducible synthesis of amorphous bismuth nanoparticles incorporated into a polysaccharide matrix using a photoreduction process is presented. As precursor for the generation of the Bi nanoparticles, organosoluble triphenylbismuth is used. The precursor is dissolved in toluene and mixed with a hydrophobic organosoluble polysaccharide, namely trimethylsilyl cellulose (TMSC) with high DSSi. The solution is subjected to UV exposure, which induces the homolytic cleavage of the bismuth-carbon bond in BiPh3 resulting in the formation of Bi(0) and phenyl radicals. The aggregation of the Bi atoms can be controlled in the TMSC matrix and yields nanoparticles of around 20 nm size as proven by TEM. The phenyl radicals undergo recombination to form small organic molecules like benzene and biphenyl, which can be removed from the nanocomposite after lyophilization and exposure to high vacuum. Finally, the TMSC matrix is converted to cellulose after exposure to HCl vapors, which remove the trimethylsilyl groups from the TMSC derivative. Although TMSC is converted to cellulose, the formed TMS-OH is not leaving the nanocomposite but reacts instead with surface oxide layer of the Bi nanoparticles to form silylated Bi nanoparticles as proven by TEM/EDX.

  5. OPTIMAL BETA-RAY SHIELDING THICKNESSES FOR DIFFERENT THERAPEUTIC RADIONUCLIDES AND SHIELDING MATERIALS.

    Science.gov (United States)

    Cho, Yong In; Kim, Ja Mee; Kim, Jung Hoon

    2016-04-06

    To better understand the distribution of deposited energy of beta and gamma rays according to changes in shielding materials and thicknesses when radionuclides are used for therapeutic nuclear medicine, a simulation was conducted. The results showed that due to the physical characteristics of each therapeutic radionuclide, the thicknesses of shielding materials at which beta-ray shielding takes place varied. Additional analysis of the shielding of gamma ray was conducted for radionuclides that emit both beta and gamma rays simultaneously with results showing shielding effects proportional to the atomic number and density of the shielding materials. Also, analysis of bremsstrahlung emission after beta-ray interactions in the simulation revealed that the occurrence of bremsstrahlung was relatively lower than theoretically calculated and varied depending on different radionuclides.

  6. Neutron shielding material based on colemanite and epoxy resin.

    Science.gov (United States)

    Okuno, Koichi

    2005-01-01

    In recent years, there has been a need for compact shielding design such as self-shielding of a PET cyclotron or upgradation of radiation machinery in existing facilities. In these cases, high performance shielding materials are needed. Concrete or polyethylene have been used for a neutron shield. However, for compact shielding, they fall short in terms of performance or durability. Therefore, a new type of neutron shielding material based on epoxy resin and colemanite has been developed. Slab attenuation experiments up to 40 cm for the new shielding material were carried out using a 252Cf neutron source. Measurement was carried out using a REM-counter, and compared with calculation. The results show that the shielding performance is better than concrete and polyethylene mixed with 10 wt% boron oxide. From the result, we confirmed that the performance of the new material is suitable for practical use.

  7. Colloidal bismuth subcitrate in non-ulcer dyspepsia.

    Directory of Open Access Journals (Sweden)

    Khanna M

    1992-07-01

    Full Text Available The effect of colloidal bismuth subcitrate (De-Nol on symptoms, Helicobacter pylori status and histological features was studied in 35 patients with non-ulcer dyspepsia. Pain (34 cases and gas bloat (18 were the predominant symptoms. H pylori was present in 26 (74.3% patients. Gastritis and duodenitis were present in 29 of 32 and 22 of 31 cases respectively in whom biopsies were available. Relief in symptoms after treatment was seen in 29 (82.8% cases. Improvement in gastritis and duodenitis was noted in 60.8% and 58.8% respectively; over 70% of H pylori positive patients cleared the organism. These changes did not correlate with the relief in symptoms. We conclude that colloidal bismuth subcitrate is effective in the short term treatment of non-ulcer dyspepsia. It also clears H pylori infection and results in improvement of histological features.

  8. Bismuth Telluride and Its Alloys as Materials for Thermoelectric Generation

    Directory of Open Access Journals (Sweden)

    H. Julian Goldsmid

    2014-03-01

    Full Text Available Bismuth telluride and its alloys are widely used as materials for thermoelectric refrigeration. They are also the best materials for use in thermoelectric generators when the temperature of the heat source is moderate. The dimensionless figure of merit, ZT, usually rises with temperature, as long as there is only one type of charge carrier. Eventually, though, minority carrier conduction becomes significant and ZT decreases above a certain temperature. There is also the possibility of chemical decomposition due to the vaporization of tellurium. Here we discuss the likely temperature dependence of the thermoelectric parameters and the means by which the composition may be optimized for applications above room temperature. The results of these theoretical predictions are compared with the observed properties of bismuth telluride-based thermoelements at elevated temperatures. Compositional changes are suggested for materials that are destined for generator modules.

  9. Lead-bismuth eutectic recrystallization studies for the Megapie target

    Energy Technology Data Exchange (ETDEWEB)

    Zucchini, A. [ENEA, FIS/MET, Centro Ricerche ' E.Clementel' , via Don Fiammelli 2, 40128 Bologna (Italy); Agostini, P. [ENEA, FIS/ING, Centro Ricerche Brasimone, 40032 Camugnano, Bologna (Italy); Baicchi, E. [ENEA, FIS/ING, Centro Ricerche Brasimone, 40032 Camugnano (Bologna) (Italy)]. E-mail: elio.baicchi@brasimone.enea.it

    2005-02-01

    The expansion behaviour after freezing of the lead-bismuth eutectic (LBE) with 44.5% lead and 55.5% bismuth is described according to the reported theory. The issue of the vessel structural integrity after LBE recrystallization was dealt with by experimental and numerical studies performed in the frame of the Megapie (Megawatt Pilot Experiment) project. We have identified the important elements which, in the case of LBE solidification inside the Megapie target, play a role in the reduction of the possible vessel over-stressing; among them, the LBE yield strength has been tested under significant experimental conditions. The resulting suggestions can also be related to the design and to the freezing procedures for other LBE technology facilities.

  10. Ab initio electronic structure and optical conductivity of bismuth tellurohalides

    CERN Document Server

    Schwalbe, Sebastian; Starke, Ronald; Schober, Giulio A H; Kortus, Jens

    2016-01-01

    We investigate the electronic structure, dielectric and optical properties of bismuth tellurohalides BiTeX (X = I, Cl, Br) by means of all-electron density functional theory. In particular, we present the ab initio conductivities and dielectric tensors calculated over a wide frequency range, and compare our results with the recent measurements by Akrap et al. , Makhnev et al. , and Rusinov et al. . We show how the low-frequency branch of the optical conductivity can be used to identify characteristic intra- and interband transitions between the Rashba spin-split bands in all three bismuth tellurohalides. We further calculate the refractive indices and dielectric constants, which in turn are systematically compared to previous predictions and measurements. We expect that our quantitative analysis will contribute to the general assessment of bulk Rashba materials for their potential use in spintronics devices.

  11. Mars Exploration Rover Heat Shield Recontact Analysis

    Science.gov (United States)

    Raiszadeh, Behzad; Desai, Prasun N.; Michelltree, Robert

    2011-01-01

    The twin Mars Exploration Rover missions landed successfully on Mars surface in January of 2004. Both missions used a parachute system to slow the rover s descent rate from supersonic to subsonic speeds. Shortly after parachute deployment, the heat shield, which protected the rover during the hypersonic entry phase of the mission, was jettisoned using push-off springs. Mission designers were concerned about the heat shield recontacting the lander after separation, so a separation analysis was conducted to quantify risks. This analysis was used to choose a proper heat shield ballast mass to ensure successful separation with low probability of recontact. This paper presents the details of such an analysis, its assumptions, and the results. During both landings, the radar was able to lock on to the heat shield, measuring its distance, as it descended away from the lander. This data is presented and is used to validate the heat shield separation/recontact analysis.

  12. Zerovalent bismuth nanoparticles inhibit Streptococcus mutans growth and formation of biofilm

    Directory of Open Access Journals (Sweden)

    Hernandez-Delgadillo R

    2012-04-01

    Full Text Available Rene Hernandez-Delgadillo1, Donaji Velasco-Arias2, David Diaz2, Katiushka Arevalo-Niño1, Marianela Garza-Enriquez1, Myriam A De la Garza-Ramos1, Claudio Cabral-Romero11Instituto de Biotecnologia, Centro de Investigacion y Desarrollo en Ciencias de la Salud, CIDICS, Facultad de Odontologia, Universidad Autonoma de Nuevo Leon, UANL, Monterrey, Nuevo Leon, 2Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Distrito Federal, MexicoBackground and methods: Despite continuous efforts, the increasing prevalence of resistance among pathogenic bacteria to common antibiotics has become one of the most significant concerns in modern medicine. Nanostructured materials are used in many fields, including biological sciences and medicine. While some bismuth derivatives has been used in medicine to treat vomiting, nausea, diarrhea, and stomach pain, the biocidal activity of zerovalent bismuth nanoparticles has not yet been studied. The objective of this investigation was to analyze the antimicrobial activity of bismuth nanoparticles against oral bacteria and their antibiofilm capabilities.Results: Our results showed that stable colloidal bismuth nanoparticles had 69% antimicrobial activity against Streptococcus mutans growth and achieved complete inhibition of biofilm formation. These results are similar to those obtained with chlorhexidine, the most commonly used oral antiseptic agent. The minimal inhibitory concentration of bismuth nanoparticles that interfered with S. mutans growth was 0.5 mM.Conclusion: These results suggest that zerovalent bismuth nanoparticles could be an interesting antimicrobial agent to be incorporated into an oral antiseptic preparation.Keywords: zerovalent bismuth nanoparticles, antimicrobial agent, biofilm, Streptococcus mutans

  13. Bismuth oxide aqueous colloidal nanoparticles inhibit Candida albicans growth and biofilm formation

    Directory of Open Access Journals (Sweden)

    Hernandez-Delgadillo R

    2013-04-01

    Full Text Available Rene Hernandez-Delgadillo,1 Donaji Velasco-Arias,3 Juan Jose Martinez-Sanmiguel,2 David Diaz,3 Inti Zumeta-Dube,3 Katiushka Arevalo-Niño,1 Claudio Cabral-Romero2 1Facultad de Ciencias Biológicas, Instituto de Biotecnologia, Universidad Autonoma de Nuevo Leon, UANL, Monterrey, Mexico; 2Facultad de Odontología, Universidad Autonoma de Nuevo Leon, UANL, Monterrey, México; 3Facultad de Quimica, Universidad Nacional Autonoma de Mexico, UNAM, Distrito Federal, México Abstract: Multiresistance among microorganisms to common antimicrobials has become one of the most significant concerns in modern medicine. Nanomaterials are a new alternative to successfully treat the multiresistant microorganisms. Nanostructured materials are used in many fields, including biological sciences and medicine. Recently, it was demonstrated that the bactericidal activity of zero-valent bismuth colloidal nanoparticles inhibited the growth of Streptococcus mutans; however the antimycotic potential of bismuth nanostructured derivatives has not yet been studied. The main objective of this investigation was to analyze the fungicidal activity of bismuth oxide nanoparticles against Candida albicans, and their antibiofilm capabilities. Our results showed that aqueous colloidal bismuth oxide nanoparticles displayed antimicrobial activity against C. albicans growth (reducing colony size by 85% and a complete inhibition of biofilm formation. These results are better than those obtained with chlorhexidine, nystatin, and terbinafine, the most effective oral antiseptic and commercial antifungal agents. In this work, we also compared the antimycotic activities of bulk bismuth oxide and bismuth nitrate, the precursor metallic salt. These results suggest that bismuth oxide colloidal nanoparticles could be a very interesting candidate as a fungicidal agent to be incorporated into an oral antiseptic. Additionally, we determined the minimum inhibitory concentration for the synthesized

  14. On the morphometry of terrestrial shield volcanoes

    Science.gov (United States)

    Grosse, Pablo; Kervyn, Matthieu

    2016-04-01

    Shield volcanoes are described as low angle edifices that have convex up topographic profiles and are built primarily by the accumulation of lava flows. This generic view of shields' morphology is based on a limited number of monogenetic shields from Iceland and Mexico, and a small set of large oceanic islands (Hawaii, Galapagos). Here, the morphometry of over 150 monogenetic and polygenetic shield volcanoes, identified inthe Global Volcanism Network database, are analysed quantitatively from 90-meter resolution DEMs using the MORVOLC algorithm. An additional set of 20 volcanoes identified as stratovolcanoes but having low slopes and being dominantly built up by accumulation of lava flows are documented for comparison. Results show that there is a large variation in shield size (volumes range from 0.1 to >1000 km3), profile shape (height/basal width ratios range from 0.01 to 0.1), flank slope gradients, elongation and summit truncation. Correlation and principal component analysis of the obtained quantitative database enables to identify 4 key morphometric descriptors: size, steepness, plan shape and truncation. Using these descriptors through clustering analysis, a new classification scheme is proposed. It highlights the control of the magma feeding system - either central, along a linear structure, or spatially diffuse - on the resulting shield volcano morphology. Genetic relationships and evolutionary trends between contrasted morphological end-members can be highlighted within this new scheme. Additional findings are that the Galapagos-type morphology with a central deep caldera and steep upper flanks are characteristic of other shields. A series of large oceanic shields have slopes systematically much steeper than the low gradients (<4-8°) generally attributed to large Hawaiian-type shields. Finally, the continuum of morphologies from flat shields to steeper complex volcanic constructs considered as stratovolcanoes calls for a revision of this oversimplified

  15. Atomic Layer Deposition of Bismuth Vanadates for Solar Energy Materials.

    Science.gov (United States)

    Stefik, Morgan

    2016-07-07

    The fabrication of porous nanocomposites is key to the advancement of energy conversion and storage devices that interface with electrolytes. Bismuth vanadate, BiVO4 , is a promising oxide for solar water splitting where the controlled fabrication of BiVO4 layers within porous, conducting scaffolds has remained a challenge. Here, the atomic layer deposition of bismuth vanadates is reported from BiPh3 , vanadium(V) oxytriisopropoxide, and water. The resulting films have tunable stoichiometry and may be crystallized to form the photoactive scheelite structure of BiVO4 . A selective etching process was used with vanadium-rich depositions to enable the synthesis of phase-pure BiVO4 after spinodal decomposition. BiVO4 thin films were measured for photoelectrochemical performance under AM 1.5 illumination. The average photocurrents were 1.17 mA cm(-2) at 1.23 V versus the reversible hydrogen electrode using a hole-scavenging sulfite electrolyte. The capability to deposit conformal bismuth vanadates will enable a new generation of nanocomposite architectures for solar water splitting.

  16. Aerosol deposition of (Cu,Ti) substituted bismuth vanadate films

    Energy Technology Data Exchange (ETDEWEB)

    Exner, Jörg, E-mail: Functional.Materials@Uni-Bayreuth.de [University of Bayreuth, Department of Functional Materials, Universitätsstraße 30, 95440 Bayreuth (Germany); Fuierer, Paul [Materials and Metallurgical Engineering Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States); Moos, Ralf [University of Bayreuth, Department of Functional Materials, Universitätsstraße 30, 95440 Bayreuth (Germany)

    2014-12-31

    Bismuth vanadate, Bi{sub 4}V{sub 2}O{sub 11}, and related compounds with various metal (Me) substitutions, Bi{sub 4}(Me{sub x}V{sub 1−x}){sub 2}O{sub 11−δ}, show some of the highest ionic conductivities among the known solid oxide electrolytes. Films of Cu and Ti substituted bismuth vanadate were prepared by an aerosol deposition method, a spray coating process also described as room temperature impact consolidation. Resultant films, several microns in thickness, were dense with good adhesion to the substrate. Scanning electron microscopy and high temperature X-ray diffraction were used to monitor the effects of temperature on the structure and microstructure of the film. The particle size remained nano-scale while microstrain decreased rapidly up to 500 °C, above which coarsening and texturing increased rapidly. Impedance measurements of films deposited on inter-digital electrodes revealed an annealing effect on the ionic conductivity, with the conductivity exceeding that of a screen printed film, and approaching that of bulk ceramic. - Highlights: • Cu and Ti doped bismuth vanadate films were prepared by aerosol deposition (AD). • Dense 3–5 μm thick films were deposited on alumina, silicon and gold electrodes. • Annealing of the AD-layer increases the conductivity by 1.5 orders of magnitude. • Effect of temperature on structure and microstructure was investigated.

  17. Thermal degradation of ultrabroad bismuth NIR luminescence in bismuth-doped tantalum germanate laser glasses.

    Science.gov (United States)

    Wang, Liping; Zhao, Yanqi; Xu, Shanhui; Peng, Mingying

    2016-04-01

    Because of ultra-broadband luminescence in 1000-1700 nm and consequent applications in fiber amplifier and lasers in the new spectral range where traditional rare earth cannot work, bismuth-doped laser glasses have received rising interest recently. For long-term practical application, thermal degradation must be considered for the glasses. This, however, has seldom been investigated. Here we report the thermal degradation of bismuth-doped germanate glass. Heating and cooling cycle experiments at high temperature reveal strong dependence of the thermal degradation on glass compositions. Bismuth and tantalum lead to the reversible degradation, while lithium can produce permanent irreversible degradation. The degradation becomes worse as lithium content increases in the glass. Absorption spectra show this is due to partial oxidation of bismuth near-infrared emission center. Surprisingly, we notice the emission of bismuth exhibits blueshift, rather than redshift at a higher temperature, and the blueshift can be suppressed by increasing the lithium content.

  18. The use of nipple shields: A review

    Directory of Open Access Journals (Sweden)

    Selina Chow

    2016-11-01

    Full Text Available A nipple shield is a breastfeeding aid with a nipple-shaped shield that is positioned over the nipple and areola prior to nursing. Nipple shields are usually recommended to mothers with flat nipples or in cases in which there is a failure of the baby to effectively latch onto the breast within the first two days postpartum. The use of nipple shields is a controversial topic in the field of lactation. Its use has been an issue in the clinical literature since some older studies discovered reduced breast milk transfer when using nipple shields, while more recent studies reported successful breastfeeding outcomes. The purpose of this review was to examine the evidence and outcomes with nipple shield use. Methods: A literature search was conducted in Ovid MEDLINE, OLDMEDLINE, EMBASE Classic, EMBASE, Cochrane Central Register of Controlled Trials and CINAHL. The primary endpoint was any breastfeeding outcome following nipple shield use. Secondary endpoints included the reasons for nipple shield use and the average/median length of use. For the analysis, we examined the effect of nipple shield use on physiological responses, premature infants, mothers’ experiences, and health professionals’ experiences. Results: The literature search yielded 261 articles, 14 of which were included in this review. Of these 14 articles, three reported on physiological responses, two reported on premature infants, eight reported on mothers’ experiences, and one reported on health professionals’ experiences. Conclusion: Through examining the use of nipple shields, further insight is provided on the advantages and disadvantages of this practice, thus allowing clinicians and researchers to address improvements on areas that will benefit mothers and infants the most.

  19. Radiation Shielding Materials

    Science.gov (United States)

    Adams, James H., Jr.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    NASA has relied on the materials to provide radiation shielding for astronauts since the first manned flights. Until very recently existing materials in the structure of manned spacecraft as well as the equipment and consumables onboard have been taken advantage of for radiation shielding. With the advent of the International Space Station and the prospect of extended missions to the Moon or Mars, it has been found that the materials, which were included in the spacecraft for other reasons, do not provide adequate shielding. For the first time materials are being added to manned missions solely to improve the radiation shielding. It is now recognized that dual use materials must be identified/developed. These materials must serve a purpose as part of the spacecraft or its cargo and at the same time be good shielding. This paper will review methods for evaluating the radiation shielding effectiveness of materials and describe the character of materials that have high radiation shielding effectiveness. Some candidate materials will also be discussed.

  20. Shielding high energy accelerators

    CERN Document Server

    Stevenson, Graham Roger

    2001-01-01

    After introducing the subject of shielding high energy accelerators, point source, line-of-sight models, and in particular the Moyer model. are discussed. Their use in the shielding of proton and electron accelerators is demonstrated and their limitations noted. especially in relation to shielding in the forward direction provided by large, flat walls. The limitations of reducing problems to those using it cylindrical geometry description are stressed. Finally the use of different estimators for predicting dose is discussed. It is suggested that dose calculated from track-length estimators will generally give the most satisfactory estimate. (9 refs).

  1. Sulfate-reducing bacteria slow intestinal transit in a bismuth-reversible fashion in mice.

    Science.gov (United States)

    Ritz, N L; Lin, D M; Wilson, M R; Barton, L L; Lin, H C

    2017-01-01

    Hydrogen sulfide (H2 S) serves as a mammalian cell-derived gaseous neurotransmitter. The intestines are exposed to a second source of this gas by sulfate-reducing bacteria (SRB). Bismuth subsalicylate binds H2 S rendering it insoluble. The aim of this study was to test the hypothesis that SRB may slow intestinal transit in a bismuth-reversible fashion. Eighty mice were randomized to five groups consisting of Live SRB, Killed SRB, SRB+Bismuth, Bismuth, and Saline. Desulfovibrio vulgaris, a common strain of SRB, was administered by gavage at the dose of 1.0 × 10(9) cells along with rhodamine, a fluorescent dye. Intestinal transit was measured 50 minutes after gavage by euthanizing the animals, removing the small intestine between the pyloric sphincter and the ileocecal valve and visualizing the distribution of rhodamine across the intestine using an imaging system (IVIS, Perkin-Elmer). Intestinal transit (n=50) was compared using geometric center (1=minimal movement, 100=maximal movement). H2 S concentration (n=30) was also measured when small intestinal luminal content was allowed to generate this gas. The Live SRB group had slower intestinal transit as represented by a geometric center score of 40.2 ± 5.7 when compared to Saline: 73.6 ± 5.7, Killed SRB: 77.9 ± 6.9, SRB+Bismuth: 81.0 ± 2.0, and Bismuth: 73.3 ± 4.2 (Pfashion in mice. Our results demonstrate that intestinal transit is slowed by SRB and this effect could be abolished by H2 S-binding bismuth. © 2016 John Wiley & Sons Ltd.

  2. Bismuth pyrochlore-based thin films for dielectric energy storage

    Science.gov (United States)

    Michael, Elizabeth K.

    The drive towards the miniaturization of electronic devices has created a need for dielectric materials with large energy storage densities. These materials, which are used in capacitors, are a critical component in many electrical systems. Here, the development of dielectric energy storage materials for pulsed power applications, which require materials with the ability to accumulate a large amount of energy and then deliver it to the system rapidly, is explored. The amount of electrostatic energy that can be stored by a material is a function of the induced polarization and the dielectric breakdown strength of the material. An ideal energy storage dielectric would possess a high relative permittivity, high dielectric breakdown strength, and low loss tangent under high applied electric fields. The bismuth pyrochlores are a compositionally tunable family of materials that meet these requirements. Thin films of cubic pyrochlore bismuth zinc niobate, bismuth zinc tantalate, and bismuth zinc niobate tantalate, were fabricated using a novel solution chemistry based upon the Pechini method. This solution preparation is advantageous because it avoids the use of teratogenic solvents, such as 2-methoxyethanol. Crystalline films fabricated using this solution chemistry had very small grains that were approximately 27 nm in lateral size and 35 nm through the film thickness. Impedance measurements found that the resistivity of the grain boundaries was two orders of magnitude higher than the resistivity of the grain interior. The presence of many resistive grain boundaries impeded conduction through the films, resulting in high breakdown strengths for these materials. In addition to high breakdown strengths, this family of materials exhibited moderate relative permittivities of between 55 +/- 2 and 145 +/- 5, for bismuth zinc tantalate and bismuth zinc niobate, respectively, and low loss tangents on the order of 0.0008 +/- 0.0001. Increases in the concentration of the tantalum

  3. iSHIELD - A Line Source Application of SHIELD11

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, W.R.; Rokni, S.H.; /SLAC

    2006-04-27

    iSHIELD11 performs a line-source numerical integration of radiation source terms that are defined by the iSHIELD11 computer code[1] . An example is provided to demonstrate how one can use iSHIELD11 to perform a shielding analysis for a 250 GeV electron linear accelerator.

  4. Neutronic Reactor Shield

    Science.gov (United States)

    Fermi, Enrico; Zinn, Walter H.

    The argument of the present Patent is a radiation shield suitable for protection of personnel from both gamma rays and neutrons. Such a shield from dangerous radiations is achieved to the best by the combined action of a neutron slowing material (a moderator) and a neutron absorbing material. Hydrogen is particularly effective for this shield since it is a good absorber of slow neutrons and a good moderator of fast neutrons. The neutrons slowed down by hydrogen may, then, be absorbed by other materials such as boron, cadmium, gadolinium, samarium or steel. Steel is particularly convenient for the purpose, given its effectiveness in absorbing also the gamma rays from the reactor (both primary gamma rays and secondary ones produced by the moderation of neutrons). In particular, in the present Patent a shield is described, made of alternate layers of steel and Masonite (an hydrolized ligno-cellulose material). The object of the present Patent is not discussed in any other published paper.

  5. Adhesive particle shielding

    Science.gov (United States)

    Klebanoff, Leonard Elliott; Rader, Daniel John; Walton, Christopher; Folta, James

    2009-01-06

    An efficient device for capturing fast moving particles has an adhesive particle shield that includes (i) a mounting panel and (ii) a film that is attached to the mounting panel wherein the outer surface of the film has an adhesive coating disposed thereon to capture particles contacting the outer surface. The shield can be employed to maintain a substantially particle free environment such as in photolithographic systems having critical surfaces, such as wafers, masks, and optics and in the tools used to make these components, that are sensitive to particle contamination. The shield can be portable to be positioned in hard-to-reach areas of a photolithography machine. The adhesive particle shield can incorporate cooling means to attract particles via the thermophoresis effect.

  6. Liquid Bismuth Propellant Flow Sensor

    Science.gov (United States)

    Polzin, Kurt A.; Stanojev, B. J.; Korman, V.

    2007-01-01

    Quantifying the propellant mass flow rate in liquid bismuth-fed electric propulsion systems has two challenging facets. First, the flow sensors must be capable of providing a resolvable measurement at propellant mass flow rates on the order of 10 mg/see with and uncertainty of less that 5%. The second challenge has to do with the fact that the materials from which the flow sensors are fabricated must be capable of resisting any of the corrosive effects associated with the high-temperature propellant. The measurement itself is necessary in order to properly assess the performance (thrust efficiency, Isp) of thruster systems in the laboratory environment. The hotspot sensor[I] has been designed to provide the bismuth propellant mass flow rate measurement. In the hotspot sensor, a pulse of thermal energy (derived from a current pulse and associated joule heating) is applied near the inlet of the sensor. The flow is "tagged" with a thermal feature that is convected downstream by the flowing liquid metal. Downstream, a temperature measurement is performed to detect a "ripple" in the local temperature associated with the passing "hotspot" in the propellant. By measuring the time between the upstream generation and downstream detection of the thermal feature, the flow speed can be calculated using a "time of flight" analysis. In addition, the system can be calibrated by measuring the accumulated mass exiting the system as a-function of time and correlating this with the time it takes the hotspot to convect through the sensor. The primary advantage of this technique is that it doesn't depend on an absolute measurement of temperature but, instead, relies on the observation of thermal features. This makes the technique insensitive to other externally generated thermal fluctuations. In this paper, we describe experiments performed using the hotspot flow sensor aimed at quantifying the resolution of the sensor technology. Propellant is expelled onto an electronic scale to

  7. Shielded cells transfer automation

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, J J

    1984-01-01

    Nuclear waste from shielded cells is removed, packaged, and transferred manually in many nuclear facilities. Radiation exposure is absorbed by operators during these operations and limited only through procedural controls. Technological advances in automation using robotics have allowed a production waste removal operation to be automated to reduce radiation exposure. The robotic system bags waste containers out of glove box and transfers them to a shielded container. Operators control the system outside the system work area via television cameras. 9 figures.

  8. Evaluation of Personal Shields Used in Selected Radiology Departments

    Directory of Open Access Journals (Sweden)

    Mohsen Salmanvandi

    2015-05-01

    Full Text Available Introduction The purpose of this study was to evaluate personal shields in radiation departments of hospitals affiliated to Mashhad University of Medical Sciences. Materials and Methods First, the information related to 109 personal shields was recorded and evaluated by imaging equipment. Afterwards, the equivalent lead thickness (ELT of 62 personal shields was assessed, using dosimeter and standard lead layers at 100 kVp. Results In this study, 109 personal shields were assessed in terms of tears, holes and cracks. The results showed that 18 shields were damaged. Moreover, ELT was evaluated in 62 shields. As the results indicated, ELT was unacceptable in 8 personal shields and lower than expected in 9 shields. Conclusion According to the results, 16.5% of personal shields had defects (tears, holes and cracks and 13% of them were unacceptable in terms of ELT and needed to be replaced. Therefore, regular quality control of personal shields and evaluation of new shields are necessary at any radiation department.

  9. Optimization design of electromagnetic shielding composites

    Science.gov (United States)

    Qu, Zhaoming; Wang, Qingguo; Qin, Siliang; Hu, Xiaofeng

    2013-03-01

    The effective electromagnetic parameters physical model of composites and prediction formulas of composites' shielding effectiveness and reflectivity were derived based on micromechanics, variational principle and electromagnetic wave transmission theory. The multi-objective optimization design of multilayer composites was carried out using genetic algorithm. The optimized results indicate that material parameter proportioning of biggest absorption ability can be acquired under the condition of the minimum shielding effectiveness can be satisfied in certain frequency band. The validity of optimization design model was verified and the scheme has certain theoretical value and directive significance to the design of high efficiency shielding composites.

  10. The cytotoxicity of organobismuth compounds with certain molecular structures can be diminished by replacing the bismuth atom with an antimony atom in the molecules.

    Science.gov (United States)

    Kohri, Kumiko; Yoshida, Eiko; Yasuike, Shuji; Fujie, Tomoya; Yamamoto, Chika; Kaji, Toshiyuki

    2015-06-01

    Organic-inorganic hybrid molecules, which are composed of an organic structure and metal(s), are indispensable for synthetic chemical reactions; however, their toxicity has been incompletely understood. In the present study, we discovered two cytotoxic organobismuth compounds whose cytotoxicity diminished upon replacement of the intramolecular bismuth atom with an antimony atom. The intracellular accumulation of the organobismuth compounds was much higher than that of the organoantimony compounds with the corresponding organic structures. We also showed that both the organic structure and bismuth atom are required for certain organobismuth compounds to exert their cytotoxic effect, suggesting that the cytotoxicity of such a compound is a result of an interaction between the organic structure and the bismuth atom. The present data suggest that organobismuth compounds with certain molecular structures exhibit cytotoxicity via an interaction between the molecular structure and the bismuth atom, and this cytotoxicity can be diminished by replacing the bismuth atom with an antimony atom, resulting in lower intracellular accumulation.

  11. Conductance measurements on bismuth nanobridges

    Energy Technology Data Exchange (ETDEWEB)

    Pernau, H.F.; Schirm, C.; Scheer, E. [Univ. of Konstanz (Germany) Dept. of Physics

    2007-07-01

    By electron beam lithography and reactive ion etching we fabricate freestanding metallic bismuth nano-bridges which serve as starting point for arranging atomic-size and tunnel contacts with the help of the mechanically controlled breakjunction technique. Since the bridges are broken in cryogenic vacuum, the contacts are free of oxygen or other contamination. The transport measurements are performed in a {sup 3}He cryostat in the temperature range from 0.25 K up to 2 K and in transverse magnetic fields up to 8 T. After determining the preferred conductance values by recording conductance histograms, we study the conductance as a function of temperature, bias voltage and magnetic field at various contact values corresponding to those preferred conductance values. We observe reproducible conductance fluctuations as a function of both bias voltage and magnetic field and a well pronounced zero-bias anomaly which is modulated periodically with the magnetic field. We interprete our data in terms of phase coherent transport and onsetting superconductivity due to the granular structure of the film. (orig.)

  12. Bismuth nanoparticles synthesized by laser ablation in lubricant oils for tribological tests

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Castañeda, M., E-mail: mar.floc@hotmail.com [Universidad Autónoma del Estado de México, Av. Instituto Literario No. 100, Oriente Col. Centro, Toluca, Estado de México C.P. 50000, México (Mexico); Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca s/n, La Marquesa, Ocoyoacac, Edo. de México C.P. 52750, México (Mexico); Camps, E. [Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca s/n, La Marquesa, Ocoyoacac, Edo. de México C.P. 52750, México (Mexico); Camacho-López, M. [Universidad Autónoma del Estado de México, Av. Instituto Literario No. 100, Oriente Col. Centro, Toluca, Estado de México C.P. 50000, México (Mexico); Muhl, S. [Instituto de Investigación en Materiales (UNAM), Circuito Exterior, Ciudad Universitaria, Coyoacán, 04510 México, D.F., México (Mexico); and others

    2015-09-15

    Highlights: • Bismuth nanoparticles have been obtained by laser ablation of solids in liquids. • The technique allows controlling the size and concentration of the samples. • Bi np’s in base oils can improve the tribological characteristics of the lubricant. - Abstract: The improvement of the tribological properties of mineral base oils through the addition of bismuth nanoparticles as an additive, together with the idea of obtaining lubricants free of heavy metals, was evaluated. Bismuth nanoparticles were produced directly in the heavy and light viscosity mineral base oils (BS900 and BS6500) using the technique of laser ablation of solids immersed in liquids. Transmission electron microscopy measurements showed the presence of pure bismuth nanoparticles. Small Angle X-ray Scattering (SAXS) measurements showed that the average size of the nanoparticles was between 7 and 65 nm depending on the experimental conditions used. The tribological properties of the base oil with the bismuth nanoparticles additives were evaluated using a four-ball tester. Tests were performed using the base oil with and without Bi nanoparticles. It was observed that the coefficient of friction of the oil decrease with an increasing concentration of the nanoparticles. The results also showed that the wear rate was reduced when the Bi nanoparticle additives were used.

  13. How reliable are environmental data on 'orphan' elements? The case of bismuth concentrations in surface waters.

    Science.gov (United States)

    Filella, Montserrat

    2010-01-01

    Like all elements of the periodic table, bismuth is ubiquitously distributed throughout the environment as a result of natural processes and human activities. It is present as Bi(III) in environmental, biological and geochemical samples. Although bismuth and its compounds are considered to be non-toxic to humans, its increasing use as a replacement for lead has highlighted how little is known about its environmental and ecotoxicological behaviour. In this first critical review paper on the existing information on bismuth occurrence in natural waters, 125 papers on fresh and marine waters have been collated. Although the initial objective of this study was to establish the range of the typical concentrations of total dissolved bismuth in natural waters, this proved impossible to achieve due to the wide, and hitherto unexplained, dispersion of published data. Since analytical limitations might be one of the reasons underlying value dispersion, new analytical methods published since 2000--intended to be applied to natural waters--have also been reviewed. Disappointingly, the detection limits of the bulk of them are well above those required; they are thus of limited usefulness. Analysis of the existing information on bismuth in secondary references (i.e., books, review chapters) and on its chemical speciation in seawater revealed that the uncritical reproduction of old data is a widespread practice.

  14. Melting behaviour of lead and bismuth nano-particles in quasicrystalline matrix - The role of interfaces

    Indian Academy of Sciences (India)

    Alok Singh; A P Tsai

    2003-02-01

    Nanomaterials are playing an increasingly important role in modern technologies. Interfaces are crucial in nanotechnology. In this study, we have examined the stability of nanoparticles. Major emphasis is on understanding the effect of interfaces on melting. Melting behaviour of nanocrystalline interfaces, created by embedding lead and bismuth nanoparticles in quasicrystalline matrices, was studied. Sharply faceted and coherent interfaces can be related to sharper melting transitions, while irregularly shaped and incoherent interfaces can be directly correlated with lowering of melting temperatures. It is shown here that solid lead forms a high energy interface with phason strain-free quasicrystal (resulting in a lowering of the melting temperature) while bismuth forms a low energy interface with the quasicrystal (resulting in superheating, unusual for bismuth).

  15. Poisoning effect of bismuth on modification behaviour of strontium in LM25 alloy

    Indian Academy of Sciences (India)

    S Farahany; A Ourdjini; M H Idris; L T Thai

    2011-10-01

    Nucleation and growth, temperature measurements andmicrostructure observations of silicon phase are presented for strontium modified Al–7%Si (LM25) cast alloy treated with bismuth. The results show that addition of bismuth in strontium modified alloys may have a poisoning effect resulting in lost modification of the silicon phase. With increasing Bi/Sr ratio, thermal analysis measurements showed that the eutectic growth temperature increased remarkably to 573°C and recalescence decreased to 0.2°C and the morphology of silicon displayed the same flakelike structure as in the unmodified alloys. Microstructural observation showed that a minimum Bi/Sr ratio of 1.2 which is equivalent to a Sr/Bi ratio of 0.43 is required for effective strontium modification and neutralization of the poisoning effect of bismuth.

  16. Optical properties of thermally reduced bismuth-doped sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

    Nielsen, K.H.; Smedskjær, Morten Mattrup; Yue, Yuanzheng

    , but also concerning the metal particle formation, and the broadband near infrared luminescence. Both the inward diffusion and the infrared luminescence depend on the bismuth oxidation state. The latter can be varied by adjusting the parameters of the heat-treatment, e.g., time, temperature, and partial......Heat-treatment of multivalent ion containing glasses in a hydrogen atmosphere may cause both reduction of the multivalent ions and ionic inward diffusion, resulting in improved glass properties. Bismuth-doped glasses are also interesting objects not only concerning the reduction induced diffusion...... pressure of hydrogen. Here, we present results on the effect of the heat-treatment on the optical properties of bismuth-doped sodium aluminosilicate glasses....

  17. Experimental study on the effects of bismuth subgallate on the inflammatory process and angiogenesis of the oral mucosa

    Directory of Open Access Journals (Sweden)

    Eduardo Vieira Couto

    2016-02-01

    Full Text Available ABSTRACT INTRODUCTION: Bismuth subgallate is a salt derived from heavy metal. The aim of this study was to evaluate the effect of this salt on some phases of healing. OBJECTIVES: To assess the effect of subgallate on mucosa and to evaluate the association between the use of bismuth subgallate and neogenesis of vessels in oral mucosal wounds. METHODS: This was a prospective and experimental study. This study used sixty rats, which were divided into control and experimental groups. The animals were submitted to a surgical procedure, which caused oral mucosal injury. A saline solution was applied on the wound of the control group, and in the experimental group, a solution of bismuth subgallate was administrated. RESULTS: The experimental group showed greater inflammatory reaction with increasing monomorphic proliferation. There was increased vessel proliferation in the control group. CONCLUSION: Bismuth subgallate had a negative influence on the healing process, delaying the rate of new vessel formation and optimal wound healing.

  18. Passive Magnetic Shielding in Gradient Fields

    CERN Document Server

    Bidinosti, C P

    2013-01-01

    The effect of passive magnetic shielding on dc magnetic field gradients imposed by both external and internal sources is studied. It is found that for concentric cylindrical or spherical shells of high permeability material, higher order multipoles in the magnetic field are shielded progressively better, by a factor related to the order of the multipole. In regard to the design of internal coil systems for the generation of uniform internal fields, we show how one can take advantage of the coupling of the coils to the innermost magnetic shield to further optimize the uniformity of the field. These results demonstrate quantitatively a phenomenon that was previously well-known qualitatively: that the resultant magnetic field within a passively magnetically shielded region can be much more uniform than the applied magnetic field itself. Furthermore we provide formulae relevant to active magnetic compensation systems which attempt to stabilize the interior fields by sensing and cancelling the exterior fields clos...

  19. Photobleaching effect in bismuth-doped germanosilicate fibers.

    Science.gov (United States)

    Firstov, Sergei; Alyshev, Sergey; Khopin, Vladimir; Melkumov, Mikhail; Guryanov, Alexey; Dianov, Evgeny

    2015-07-27

    Photoinduced reduction of absorption (photobleaching) in bismuth-doped germanosilicate fibers irradiated with 532-nm laser has been observed for the first time. It was demonstrated that bismuth-related active centers having the absorption bands at wavelengths of 1400 and 1700 nm degrade under photoexcitation at 532 nm. The photobleaching process rate was estimated using conventional stretched exponential technique. It was found that the photobleaching rate in bismuth-doped germanosilicate fibers does not depend on type of bismuth-related active center. The possible underlying mechanism of photobleaching process in bismuth-doped fibers is discussed.

  20. Bismuth nanoparticles for phenolic compounds biosensing application.

    Science.gov (United States)

    Mayorga-Martinez, Carmen C; Cadevall, Miquel; Guix, Maria; Ros, Josep; Merkoçi, Arben

    2013-02-15

    The rapid determination of trace phenolic compounds is of great importance for evaluating the total toxicity of contaminated water samples. Nowadays, electrochemical tyrosinase (Tyr) based biosensors constitute a promising technology for the in situ monitoring of phenolic compounds because of their advantages such as high selectivity, low production cost, promising response speed, potential for miniaturization, simple instrumentation and easy automatization. A mediator-free amperometric biosensor for phenolic compounds detection based on the combination of bismuth nanoparticles (BiNPs) and Tyr for phenol detections will be hereby reported. This is achieved through the integration of BiNPs/Tyr onto the working electrode of a screen printed electrode (SPE) by using glutaraldehyde as a cross-linking agent. BiNPs/Tyr biosensor is evaluated by amperometric measurements at -200 mV DC and a linear range of up to 71 μM and 100 μM and a correlation coefficient of 0.995 and 0.996 for phenol and catechol, respectively. The very low DC working potential ensures the avoidance of interferences making this biosensor an advantageous device for real sample applications. In addition, the response mechanism including the effect of BiNPs based on electrochemical studies and optical characterizations will be also discussed. The obtained results may open the way to many other BiNPs applications in the biosensing field.

  1. Stellar activity and magnetic shielding

    CERN Document Server

    Grießmeier, J -M; Lammer, H; Grenfell, J L; Stadelmann, A; Motschmann, U; 10.1017/S1743921309992961

    2010-01-01

    Stellar activity has a particularly strong influence on planets at small orbital distances, such as close-in exoplanets. For such planets, we present two extreme cases of stellar variability, namely stellar coronal mass ejections and stellar wind, which both result in the planetary environment being variable on a timescale of billions of years. For both cases, direct interaction of the streaming plasma with the planetary atmosphere would entail servere consequences. In certain cases, however, the planetary atmosphere can be effectively shielded by a strong planetary magnetic field. The efficiency of this shielding is determined by the planetary magnetic dipole moment, which is difficult to constrain by either models or observations. We present different factors which influence the strength of the planetary magnetic dipole moment. Implications are discussed, including nonthermal atmospheric loss, atmospheric biomarkers, and planetary habitability.

  2. Burnout current density of bismuth nanowires

    Science.gov (United States)

    Cornelius, T. W.; Picht, O.; Müller, S.; Neumann, R.; Völklein, F.; Karim, S.; Duan, J. L.

    2008-05-01

    Single bismuth nanowires with diameters ranging from 100nmto1μm were electrochemically deposited in ion track-etched single-pore polycarbonate membranes. The maximum current density the wires are able to carry was investigated by ramping up the current until failure occurred. It increases by three to four orders of magnitude for nanowires embedded in the template compared to bulk bismuth and rises with diminishing diameter. Simulations show that the wires are heated up electrically to the melting temperature. Since the surface-to-volume ratio rises with diminishing diameter, thinner wires dissipate the heat more efficiently to the surrounding polymer matrix and, thus, can tolerate larger current densities.

  3. Hyperfine splitting in lithium-like bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Lochmann, Matthias; Froemmgen, Nadja; Hammen, Michael; Will, Elisa [Universitaet Mainz (Germany); Andelkovic, Zoran; Kuehl, Thomas; Litvinov, Yuri; Winters, Danyal; Sanchez, Rodolfo [GSI Helmholtzzentrum, Darmstadt (Germany); Botermann, Benjamin; Noertershaeuser, Wilfried [Technische Universitaet Darmstadt (Germany); Bussmann, Michael [Helmholtzzentrum Dresden-Rossendorf (Germany); Dax, Andreas [CERN, Genf (Switzerland); Hannen, Volker; Joehren, Raphael; Vollbrecht, Jonas; Weinheimer, Christian [Universitaet Muenster (Germany); Geppert, Christopher [Universitaet Mainz (Germany); GSI Helmholtzzentrum, Darmstadt (Germany); Stoehlker, Thomas [GSI Helmholtzzentrum, Darmstadt (Germany); Universitaet Heidelberg (Germany); Thompson, Richard [Imperial College, London (United Kingdom); Volotka, Andrey [Technische Universitaet Dresden (Germany); Wen, Weiqiang [IMP Lanzhou (China)

    2013-07-01

    High-precision measurements of the hyperfine splitting values on Li- and H-like bismuth ions, combined with precise atomic structure calculations allow us to test QED-effects in the regime of the strongest magnetic fields that are available in the laboratory. Performing laser spectroscopy at the experimental storage ring (ESR) at GSI Darmstadt, we have now succeeded in measuring the hyperfine splitting in Li-like bismuth. Probing this transition has not been easy because of its extremely low fluorescence rate. Details about this challenging experiment will be given and the achieved experimental accuracy are presented.

  4. Investigation on bismuth-oxide photonic crystal fiber for optical parametric amplification

    Institute of Scientific and Technical Information of China (English)

    JIN Cang; RAO Lan; YUAN Jin-hui; SHEN Xiang-wei; YU Chong-xiu

    2011-01-01

    A hexagonal solid-core bismuth-oxide micro-structure fiber is developed to balance its dispersion and nonlinearity. This simulation and calculation results show that the bismuth-oxide photonic crystal fiber (Bi-PCF) has near zero dispersion around 1550 nm. Its dispersion slop in the communication wavelength range is also relatively flat. Moreover, both nonlinear coefficient and model field distribution are obtained. Compared with the experimental results by SiO-PCF, it can be seen that the Bi-PCF shows excellent characteristics for the optical parametric amplification (OPA).

  5. Influence of Shielding Arrangement on ECT Sensors

    Directory of Open Access Journals (Sweden)

    J. L. Fernandez Marron

    2006-09-01

    Full Text Available This paper presents a full 3D study of a shielded ECT sensor. The spatialresolution and effective sensing field are obtained by means of Finite Element Methodbased simulations and are the compared to a conventional sensor's characteristics. Aneffective improvement was found in the sensitivity in the pipe cross-section, resulting inenhanced quality of the reconstructed image. The sensing field along the axis of the sensoralso presents better behaviour for a shielded sensor.

  6. Bismuth titanate nanorods and their visible light photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Pei, L.Z., E-mail: lzpei@ahut.edu.cn; Liu, H.D.; Lin, N.; Yu, H.Y.

    2015-02-15

    Highlights: • Bismuth titanate nanorods have been synthesized by a simple hydrothermal process. • The size of bismuth titanate nanorods can be controlled by growth conditions. • Bismuth titanate nanorods show good photocatalytic activities of methylene blue and Rhodamine B. - Abstract: Bismuth titanate nanorods have been prepared using a facile hydrothermal process without additives. The bismuth titanate products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and UV-vis diffusion reflectance spectrum. XRD pattern shows that the bismuth titanate nanorods are composed of cubic Bi{sub 2}Ti{sub 2}O{sub 7} phase. Electron microscopy images show that the length and diameter of the bismuth titanate nanorods are 50-200 nm and 2 μm, respectively. Hydrothermal temperature and reaction time play important roles on the formation and size of the bismuth titanate nanorods. UV-vis diffusion reflectance spectrum indicates that bismuth titanate nanorods have a band gap of 2.58 eV. The bismuth titanate nanorods exhibit good photocatalytic activities in the photocatalytic degradation of methylene blue (MB) and Rhodamine B (RB) under visible light irradiation. The bismuth titanate nanorods with cubic Bi{sub 2}Ti{sub 2}O{sub 7} phase are a promising candidate as a visible light photocatalyst.

  7. Fluorescence Emission Centres and the Corresponding Infrared Fluorescence Saturation in a Bismuth-Doped Silica Fibre

    Institute of Scientific and Technical Information of China (English)

    QIU Yan-Qing; SHEN Yong-Hang

    2008-01-01

    We investigate the fluorescence characteristics of bismuth doped silica fibres with and without Al co-dopant which are fabricated by means of modified chemical vapour deposition (MCVD) technique, and find that the fluorescences in the red region (centred around 750nm) and in the infrared region (centred around 1100nm) may originate from different emission sites in the fibre. Strong upconversion phenomena are observed in both Al-codoped and non Al codoped bismuth fibres when the fibres are excited by an acoustic-optic Q-switched Nd: YVO4 laser. Both the aspects indicate that the upper energy level absorption reported in the work of the bismuth doped silica fibre lasers may result from the fluorescence emission sites that are not responsible for the infrared emission. It is thus expected that optimizing the compositions and the fabrication conditions of the fibre and then transferring more fluorescence emission centres are helpful for the infrared emission.

  8. Change energy photons of radiation, stimulating a photoluminescence in glasses and optical fiber, activated by bismuth

    CERN Document Server

    Ogluzdin, Valeriy E

    2011-01-01

    In the offered review ordering received and published by domestic and foreign researchers of the experimental results showing the phenomenon of a photoluminescence in glasses and optical fiber, activated by bismuth is executed, and from uniform positions representations about the process responsible for a photoluminescence in case of use for excitation of this environment of various laser sources are considered. At interpretation of process of a photoluminescence the known model considering mirror symmetry of features of frequency spectra of a photoluminescence (in this case the maximum values is used: humps or peaks of spectra of a photoluminescence) and the spectra characterising optical losses (absorption) of glass, activated by (atomic) bismuth. For the analysis values of lines of the bismuth, published in reference media are used. This model is added by earlier published specification of the author, according to which to a point of mirror symmetry of such spectra there corresponds frequency of radiation ...

  9. Radioactive Iodine (I-129) Gas Adsorption by Using Bismuth-Embedded SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jae Hwan; Cho, Yong-Jun; Park, Jang Jin; Ahn, Do-Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Yim, Man-Sung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2015-05-15

    The efficient capture of the long-lived I-129, released as off-gas from nuclear fuel reprocessing, have been of significant concern in the waste management field. In this study, bismuth-embedded SBA-15 mesoporous silica was firstly applied for iodine capture and storage. SBA-15 was functionalized with thiol (-SH) groups, followed by bismuth adsorption with Bi-S bonding, which was thermally treated to form Bi{sub 2}S{sub 3} within SBA-15. The bismuth-embedded SBA-15s demonstrated high iodine loading capacities with 540 mg-I/g-sorbent maximally, which benefitted from the high surface area and porosity of SBA-15 as well as the formation of thermodynamically stable BiI{sub 3} compound. Iodine physisorption could effectively be suppressed due to the large pores present in SBA-15, resulting in chemisorption as a main mechanism for iodine confinement.

  10. Bismuth subcarbonate as filler particle for an Epoxy-based root canal sealer

    Directory of Open Access Journals (Sweden)

    Eduardo Schwartzer

    2013-01-01

    Full Text Available Introduction: The aim of this study was to evaluate the addition of bismuth subcarbonate with different concentrations regarding the rheological properties of an experimental epoxy-based root canal sealer. Materials and Methods: Endodontic sealers were prepared with epoxy resin-based sealer with bismuth subcarbonate additions of 20%, 40%, 60%, 80%, 100%, and 120%. Flow, film thickness, working time, setting time, dimensional change, sorption, solubility, and cytotoxicity were studied according to the ISO standards. Data were statistically analyzed by one-way ANOVA, and Tukey multiple comparisons were used, with a significance level of 5%. Results: The flow, working time, water sorption, and solubility significantly decreased and the film thickness and dimensional change increased with higher filler particle addition. There were no statistically significant differences for setting time and cytotoxicity between the filler particle proportions. Conclusion: Experimental resin-based sealer with bismuth subcarbonate addition up to 40% can be an alternative for root canal sealer.

  11. Solution combustion synthesis and characterization of nanosized bismuth ferrite

    Science.gov (United States)

    Sai Kumar, V. Sesha; Rao, K. Venkateswara; Krishnaveni, T.; Kishore Goud, A. Shiva; Reddy, P. Ranjith

    2012-06-01

    The present paper describes a simple method of nanosized BiFeO3 by the solution combustion synthesis using bismuth and iron nitrates as oxidizers and the combination fuel of citric acid and ammonium hydroxide, with fuel to oxidizer ratio (Ψ = 1) one. The X-ray Diffraction results indicated rhombohedral phase (R3m) with JCPDS data card no: 72-2035. The ferroelectric transition of the sample at 8310C was detected by differential thermal analysis. Thermal analysis was done by Thermal gravimetric-Differential thermal analyzer and obtained results were presented in this paper.

  12. Gonad Shielding for Patients Undergoing Conventional Radiological Examinations: Is There Cause for Concern?

    Directory of Open Access Journals (Sweden)

    Karami

    2016-04-01

    Full Text Available Background Gonad shielding is one of the fundamental methods by which to protect reproductive organs in patients undergoing conventional radiological examinations. A lack of or inadequate shielding of the gonads may increase the exposure of these organs and result in malignancies future generations. Objectives The aim of this study is to investigate the prevalence of gonad shielding in patients undergoing conventional radiological examinations and the availability of gonad shields and gonad shielding protocols in radiology departments. Materials and Methods A retrospective, observational cross-sectional study on the application of gonad shielding, the availability of gonad shields and the existence of gonad shielding protocols in radiology departments was performed in five different hospitals in Ahvaz, Iran. Results The highest application of gonad shielding was 6.6% for the pediatric hospital. The prevalence of gonad shielding was less than 0.2%. In 64.3% of the radiography rooms, at least one flat-contact gonad shield of a large size was available. Only large-sized gonad shields were available. Curved-contact and shadow gonad shields did not exist. Gonad shielding protocols were not existence in any of the fourteen radiography rooms investigated. Conclusions Comprehensive protection programs with on-the-job training courses for staff members are strongly recommended, as well as, the provision of radiological shields and gonad shielding protocols in radiology departments to reduce the patient’s radiation dose during radiological examinations.

  13. Comparative study on solubilities of bismuth, bismuth oxide,and bismuth sulfide in hydrochloric acid-thiourea%铋、氧化铋、硫化铋在盐酸-硫脲中溶解性的比较研究

    Institute of Scientific and Technical Information of China (English)

    马哈亚·艾斯江; 巴哈尔古丽·别克吐尔逊

    2012-01-01

    在盐酸介质中及55℃加热条件下,铋与硫脲形成黄色络合物,从而建立了用分光光度法比较铋、氧化铋、硫化铋在盐酸-硫脲中溶解性的新方法.研究了反应介质、试剂浓度、加热时间、加热温度、震荡速率等因素的影响.在最佳实验条件下,溶液的质量浓度为0.04~0.24 mg/mL时符合比尔定律.相关系数R=0.999 9,检出限为1.05×10-2 μg/mL,标准偏差SD=0.003 5,相对标准偏差RSD=2.42%,摩尔吸收系数为1.515×105 L/(mol·cm),加标回收率为96.7%~98.8%.实验结果表明,铋、氧化铋、硫化铋的溶解性顺序大小为:铋>氧化铋>硫化铋.%A yellow complex is formed from bismuth and thiourea in hydrochloric acid under the heated condition of 55 °C. Thus a new method is set up to compare the solubilities of bismuth, bismuth oxide, and bismuth sulfide in hydrochloric acid-thiourea by using spectrophotometry.Effects of factors, such as reaction medium, reagent concentration, heating time, heating temperature, and oscillation speed,were studied respectively .Under the optimum experimental conditions, mass concentration of the solution is in line with Beer's law, when it is within the range of 0.04-0.24 mg/mL.The correlation coefficient (R) is 0.999 9.The detection limit is 1.05xl0-2μg/mL.The standard deviation is 0.003 5.The relative standard deviation (RSD) is 2.42%.The molar absorption coefficient is 1.515xl05 L/(mol-cm).The recovery rate of standard addition is at 96.7%~98.8%. Experimental result showed that the solubilities of bismuth,bismuth oxide,and bismuth sulfide in hydrochloric acid-thiourea is in order by size as following: Bi>Bi2O3>Bi2S3.

  14. An attenuation Layer for Electromagnetic Shielding in X- Band Frequency

    Directory of Open Access Journals (Sweden)

    vida Zaroushani

    2015-06-01

    Full Text Available Uncontrolled exposure to X-band frequency leads to health damage. One of the principles of radiation protection is shielding. But, conventional shielding materials have disadvantages. Therefore, studies of novel materials, as an alternative to conventional shielding materials, are required to obtain new electromagnetic shielding material. Therefore, this study investigated the electromagnetic shielding of two component epoxy thermosetting resin for the X - band frequency with workplace approach. Two components of epoxy resin mixed according to manufacturing instruction with the weight ratio that was 100:10 .Epoxy plates fabricated in three different thicknesses (2, 4 and 6mm and shielding effectiveness measured by Vector Network Analyzer. Then, shielding effectiveness measured by the scattering parameters.The results showed that 6mm thickness of epoxy had the highest and 2mm had the lowest average of shielding effectiveness in X-band frequency that is 4.48 and 1.9 dB, respectively. Also, shielding effectiveness increased by increasing the thickness. But this increasing is useful up to 4mm. Percentage shielding effectiveness of attenuation for 6, 4 and 2mm thicknesses is 64.35%, 63.31% and 35.40%. Also, attenuation values for 4mm and 6mm thicknesses at 8.53 GHz and 8.52 GHz frequency are 77.15% and 82.95%, respectively, and can be used as favourite shields for the above frequency. 4mm-Epoxy is a suitable candidate for shielding application in X-band frequency range but, in the lower section, 6mm thickness is recommended. Finely, the shielding matrix can be used for selecting the proper thickness for electromagnetic shielding in X- Band frequency.

  15. Probing bismuth ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Chaturvedi, Smita; Rajendra, Ranguwar; Ballav, Nirmalya; Kulkarni, Sulabha, E-mail: s.kulkarni@iiserpune.ac.in [Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008 (India); Sarkar, Indranil [DESY Photon Science, Deutsches Elektronen-Synchrotron, 22607 Hamburg (Germany); Shirolkar, Mandar M. [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Jeng, U-Ser; Yeh, Yi-Qi [National Synchrotron Radiation Research Center, 101, Hsin-Ann Road, Science Park, Hsinchu 3007-6, Taiwan (China)

    2014-09-08

    We have investigated bismuth ferrite nanoparticles (∼75 nm and ∼155 nm) synthesized by a chemical method, using soft X-ray (1253.6 eV) and hard X-ray (3500, 5500, and 7500 eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg Kα (1253.6 eV) source showed that iron and bismuth were present in both Fe{sup 3+} and Bi{sup 3+} valence states as expected for bismuth ferrite. However, hard X-ray photoelectron spectroscopy analysis of the bismuth ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi{sup 0} valence state below the surface region, indicating that bismuth ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.

  16. Making bispirin: synthesis, structure and activity against Helicobacter pylori of bismuth(III) acetylsalicylate.

    Science.gov (United States)

    Andrews, Philip C; Blair, Victoria L; Ferrero, Richard L; Junk, Peter C; Kumar, Ish

    2013-04-11

    Reaction of Bi(O(t)Bu)3 with aspirin (acetylsalicylic acid = aspH) in dry toluene results in the bismuth(III) complex, [Bi(O2C(C6H4)OAc)3]∞ 1 (O2C(C6H4)OAc = asp), minimum inhibitory concentration (MIC) against Helicobacter pylori ≥ 6.25 μg mL(-1), while the inclusion of a stoichiometric equivalent of KO(t)Bu leads to crystals of the bismuthate salt [KBi(O2C(C6H4)OAc)4]∞ 2.

  17. Structural investigations of bismuth lead borosilicate glasses under the influence of gamma irradiation through ultrasonic studies

    Science.gov (United States)

    Bootjomchai, Cherdsak; Laopaiboon, Jintana; Laopaiboon, Raewat

    2012-04-01

    The ultrasonic velocity measurements for different compositions of irradiated bismuth lead borosilicate glasses xBi2O3-(50-x)PbO-20B2O3-30SiO2 (x=2, 4, 6, 8, and 10 mol.%) were performed at room temperature using pulse-echo technique. Densities of glass samples were measured by Archimedes' principle using n-hexane as the immersion liquid. The results from the studies show that ultrasonic velocity, elastic moduli, Poisson's ratio, microhardness, and the Debye temperature increase with increasing bismuth oxide content and increasing gamma-radiation dose (3-12 Gy).

  18. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting

    OpenAIRE

    Kim, Tae Woo; Ping, Yuan; Galli, Giulia A.; Choi, Kyoung-Shin

    2015-01-01

    n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (∼2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effective...

  19. Spin-Polarized Tunneling Study on Spin-Momentum Locking in the Topological Insulator Bismuth Selenide

    Science.gov (United States)

    Chen, Ching-Tzu; Liu, Luqiao; Richardella, Anthony; Garate, Ion; Zhu, Yu; Samarth, Nitin

    2015-03-01

    In this talk, we will demonstrate that the helical spin texture on topological insulator (TI) surfaces can be electrically detected using four-terminal tunnel junction devices with ferromagnetic top electrodes. Consistent results are obtained in both the Edelstein and spin-galvanic effect configurations, allowing a quantitative determination of the charge-spin conversion efficiency in bismuth selenide. By applying finite DC biases at the junction, we further extract the energy dependence of the effective spin polarization in bismuth selenide. The observed temperature stability up to 200K suggests that TIs can be highly promising for room-temperature spintronics applications

  20. Bismuth phosphates as intermediate temperature proton conductors

    DEFF Research Database (Denmark)

    Huang, Yunjie; Christensen, Erik; Shuai, Qin

    2017-01-01

    Proton conducting electrolyte materials operational in the intermediate temperature range of 200-400 °C are of special interest for applications in fuel cells and water electrolysers. Bismuth phosphates in forms of polycrystalline powders and amorphous glasses are synthesized and investigated...

  1. Development and Investigation of Bismuth Nanowires

    Science.gov (United States)

    2008-06-05

    To: technicalreports@afosr.af.mil Subject: Final Statement to Dr. Donald Silversmith Contract/Grant Title: Development and Investigation of...Report Development and Investigation of Bismuth Nanowires – Start up phase FA9550-07-1-0472 To Dr. Donald Silversmith AFOSR PI: Jimmy Xu

  2. Undulator Beam Pipe Magnetic Shielding Effect Tests

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Andrew; Wolf, Zachary; /SLAC

    2010-11-23

    The proposed stainless steel beampipe for the LCLS undulator has a measurable shielding effect on the magnetic field of the LCLS undulators. This note describes the tests used to determine the magnitude of the shielding effect, as well as deviations in the shielding effect caused by placing different phase shims in the undulator gap. The effect of the proposed Steel strongback which will be used to support the beam pipe, was also studied. A hall probe on a 3 axis movement system was set up to measure the main component of the magnetic field in the Prototype Undulator. To account for temperature variations of the magnetic field of the undulator for successive tests, a correction is applied which is described in this technical note. Using this method, we found the shielding effect, the amount which the field inside the gap was reduced due to the placement of the beampipe, to be {approx}10 Gauss. A series of tests was also performed to determine the effect of phase shims and X and Y correction shims on the shielding. The largest effect on shielding was found for the .3 mm phase shims. The effect of the .3 mm phase shims was to increase the shielding effect {approx}4 Gauss. The tolerance for the shielding effect of the phase shims is less than 1 gauss. The effect of the strongback was seen in its permanent magnetic field. It introduced a dipole field across the measured section of the undulator of {approx}3 gauss. This note documents the tests performed to determine these effects, as well as the results of those tests.

  3. Application of nano material for shielding power-frequency electromagnetic field

    Science.gov (United States)

    Li, Hualiang; Li, Li; Liu, Jiawen

    2015-07-01

    Only limited data are available on shielding electromagnetic field exposure in professional work. In our paper, we studied the electromagnetic field intensity in 500 kV substations, and explored influence of nanomaterial in high voltage laboratory simulation. Moreover, the results of nano-fabrics material for shielding power frequency electromagnetic field indicated that, both shielding fabrics can almost completely shield the electric field, but have weak shielding effectiveness against magnetic field.

  4. Shielding effectiveness of rectangular cavity made of a new shielding material and resonance suppression

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    New shielding material has become an alternative to traditional metal to shield boxes from electromagnetic interferences. This article introduces the theory of transmission line method to study the shield boxes made of a new sort of material, and then expands the fundamental formulas to deal with the cases of multiple holes and polarization with arbitrary angle. By means of genetic algorithms with the aid of a three dimensional simulation tool, the damping of electromagnetic resonances in enclosures is researched.The computation indicates that under resonant frequency, electromagnetic resonance results in low, even negative shielding coefficient; whereas, for the same areas, shielding effectiveness of a single hole is worse than that of multiple holes. Shielding coefficient varies when polarization angle increases, and the coupled field through the rectangular aperture with the long side parallel to the thin wire is much weaker than that with the long side vertical to the thin wire. By using the metallic-loss dielectric layer of optimized calculation on the internal surface of the cavity, the best result of resonance suppression has been realized with the same thickness of coating. Finally, according to the calculation result, suggestions for shielding are proposed.

  5. The effect of bismuth subcitrate in patients with diarrhea predominant irritable bowel syndrome

    Directory of Open Access Journals (Sweden)

    Kalani M

    2010-09-01

    Full Text Available "nBackground: The irritable bowel syndrome (IBS is one of the most common chronic medical conditions. Various mechanisms, including altered gut flora and/or small bowel bacterial overgrowth, have been suggested to play a role in the development of gas-related symptoms aim of study. The clinical evidence of small intestinal bacterial overgrowth as an important etiology of irritable bowel syndrome continues to accumulate. Clinical symptoms of bacterial overgrowth and irritable bowel syndrome are similar; however, a definitive cause-and-effect relationship remains unproven. It is unclear whether motility dysfunction causes bacterial overgrowth or gas products of"nenteric bacteria affect intestinal motility in irritable bowel syndrome."n "nMethods: In a randomized double-blind placebo-controlled trial consisting of treatment with bismuth subcitrate. Primary efficacy variable was subjective symptoms; frequency of abdominal pain, Number of bowel movement & Bloating/distension."n "nResults: 119 patients were enrolled (59 bismuth subcitrate and 60 placebo recipients. At the end of phase 2, all symptom scores dropped significantly both in bismuth subcitrate and placebo group (p<0.001. There was not a significant difference in symptom relief with bismuth subcitrate versus placebo administration."n "nConclusions: There was not a significant difference in symptom relief with bismuth subcitrate versus placebo in IBS patients. Whether antibiotics can improve quality of life in patients with irritable bowel syndrome warrants further research."nInterventions: Participants were randomly assigned to receive 120mg bismuth subcitrate four times daily for 14 days (n=59 or placebo (n=60.

  6. Hinged Shields for Machine Tools

    Science.gov (United States)

    Lallande, J. B.; Poland, W. W.; Tull, S.

    1985-01-01

    Flaps guard against flying chips, but fold away for tool setup. Clear plastic shield in position to intercept flying chips from machine tool and retracted to give operator access to workpiece. Machine shops readily make such shields for own use.

  7. Arrangement of high-energy neutron irradiation field and shielding experiment using 4 m concrete at KENS.

    Science.gov (United States)

    Nakao, N; Yashima, H; Kawai, M; Oishi, K; Nakashima, H; Masumoto, K; Matsumura, H; Sasaki, S; Numajiri, M; Sanami, T; Wang, Q; Toyoda, A; Takahashi, K; Iijima, K; Eda, K; Ban, S; Hirayama, H; Muto, S; Nunomiya, T; Yonai, S; Rasolonjatovo, D R H; Terunuma, K; Yamauchi, K; Sarkar, P K; Kim, E; Nakamura, T; Maruhashi, A

    2005-01-01

    An irradiation field of high-energy neutrons produced in the forward direction from a thick tungsten target bombarded by 500 MeV protons was arranged at the KENS spallation neutron source facility. In this facility, shielding experiment was performed with an ordinary concrete shield of 4 m thickness assembled in the irradiation room, 2.5 m downstream from the target centre. Activation detectors of bismuth, aluminium, indium and gold were inserted into eight slots inside the shield and attenuations of neutron reaction rates were obtained by measurements of gamma-rays from the activation detectors. A MARS14 Monte Carlo simulation was also performed down to thermal energy, and comparisons between the calculations and measurements show agreements within a factor of 3. This neutron field is useful for studies of shielding, activation and radiation damage of materials for high-energy neutrons, and experimental data are useful to check the accuracies of the transmission and activation calculation codes.

  8. Yttrium bismuth titanate pyrochlore mixed oxides for photocatalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Merka, Oliver

    2012-10-18

    In this work, the sol-gel synthesis of new non-stoichiometric pyrochlore titanates and their application in photocatalytic hydrogen production is reported. Visible light response is achieved by introducing bismuth on the A site or by doping the B site by transition metal cations featuring partially filled d orbitals. This work clearly focusses on atomic scale structural changes induced by the systematical introduction of non-stoichiometry in pyrochlore mixed oxides and the resulting influence on the activity in photocatalytic hydrogen production. The materials were characterized in detail regarding their optical properties and their atomic structure. The pyrochlore structure tolerates tremendous stoichiometry variations. The non-stoichiometry in A{sub 2}O{sub 3} rich compositions is compensated by distortions in the cationic sub-lattice for the smaller Y{sup 3+} cation and by evolution of a secondary phase for the larger Bi{sup 3+} cation on the A site. For TiO{sub 2} rich compositions, the non-stoichiometry leads to a special vacancy formation in the A and optionally O' sites. It is shown that pyrochlore mixed oxides in the yttrium bismuth titanate system represent very active and promising materials for photocatalytic hydrogen production, if precisely and carefully tuned. Whereas Y{sub 2}Ti{sub 2}O{sub 7} yields stable hydrogen production rates over time, the bismuth richer compounds of YBiTi{sub 2}O{sub 7} and Bi{sub 2}Ti{sub 2}O{sub 7} are found to be not stable under irradiation. This drawback is overcome by applying a special co-catalyst system consisting of a precious metal core and a Cr{sub 2}O{sub 3} shell on the photocatalysts.

  9. Cytotoxic Effect of Lipophilic Bismuth Dimercaptopropanol Nanoparticles on Epithelial Cells.

    Science.gov (United States)

    Rene, Hernandez-Delgadillo; Badireddy, Appala Raju; José, Martínez-Sanmiguel Juan; Francisco, Contreras-Cordero Juan; Israel, Martinez-Gonzalez Gustavo; Isela, Sánchez-Nájera Rosa; Chellam, Shankararaman; Claudio, Cabral-Romero

    2016-01-01

    Bismuth nanoparticles have many interesting properties to be applied in biomedical and medicinal sectors, however their safety in humans have not been comprehensively investigated. The objective of this research was to determine the cytotoxic effect of bismuth dimercaptopropanol nanoparticles (BisBAL NPs) on epithelial cells. The nanoparticles are composed of 18.7 nm crystallites on average and have a rhombohedral structure, agglomerating into chains-like or clusters of small nanoparticles. Based on MTT viability assay and fluorescence microscopy, cytotoxicity was not observed on monkey kidney cells after growing with 5 µM of BisBAL NPs for 24 h. Employing same techniques, identical results were obtained with human epithelial cells (HeLa), showing a not strain-dependent phenomenon. The absence of toxic effects on epithelial cells growing with BisBAL NPs was corroborated with long-time experiments (24-72 hrs.), showing no difference in comparison with growing control (cells without nanoparticles). Further, genotoxicity assays, comet assay and fluorescent microscopy and electrophoresis in bromide-stained agarose gel revealed no damage to genomic DNA of MA104 cells after 24 h. of exposition to BisBAL NPs. Finally, the effect of bismuth nanoparticles on protein synthesis was studied in cells growing with BisBAL NPs for 24 h. SDS-PAGE assays showed no difference between treated and untreated cells, suggesting that BisBAL NPs did not interfere with protein synthesis. Hence BisBAL NPs do not appear to exert cytotoxic effects suggesting their biological compatibility with epithelial cells.

  10. Spacecraft Electrostatic Radiation Shielding

    Science.gov (United States)

    2008-01-01

    This project analyzed the feasibility of placing an electrostatic field around a spacecraft to provide a shield against radiation. The concept was originally proposed in the 1960s and tested on a spacecraft by the Soviet Union in the 1970s. Such tests and analyses showed that this concept is not only feasible but operational. The problem though is that most of this work was aimed at protection from 10- to 100-MeV radiation. We now appreciate that the real problem is 1- to 2-GeV radiation. So, the question is one of scaling, in both energy and size. Can electrostatic shielding be made to work at these high energy levels and can it protect an entire vehicle? After significant analysis and consideration, an electrostatic shield configuration was proposed. The selected architecture was a torus, charged to a high negative voltage, surrounding the vehicle, and a set of positively charged spheres. Van de Graaff generators were proposed as the mechanism to move charge from the vehicle to the torus to generate the fields necessary to protect the spacecraft. This design minimized complexity, residual charge, and structural forces and resolved several concerns raised during the internal critical review. But, it still is not clear if such a system is costeffective or feasible, even though several studies have indicated usefulness for radiation protection at energies lower than that of the galactic cosmic rays. Constructing such a system will require power supplies that can generate voltages 10 times that of the state of the art. Of more concern is the difficulty of maintaining the proper net charge on the entire structure and ensuring that its interaction with solar wind will not cause rapid discharge. Yet, if these concerns can be resolved, such a scheme may provide significant radiation shielding to future vehicles, without the excessive weight or complexity of other active shielding techniques.

  11. Improved ferrous shielding for flat cables

    Science.gov (United States)

    Drechsler, R. J.

    1969-01-01

    To improve shielding of flat multicore cables, a thin, seamless ferrous shield around all cores optimizes low frequency magnetic shielding. Such shielding is covered with an ultrathin seamless coat of highly conductive nonferrous material.

  12. Shielding Design and Radiation Shielding Evaluation for LSDS System Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Younggook; Kim, Jeongdong; Lee, Yongdeok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    As the system characteristics, the target in the spectrometer emits approximately 1012 neutrons/s. To efficiently shield the neutron, the shielding door designs are proposed for the LSDS system through a comparison of the direct shield and maze designs. Hence, to guarantee the radiation safety for the facility, the door design is a compulsory course of the development of the LSDS system. To improve the shielding rates, 250x250 covering structure was added as a subsidiary around the spectrometer. In this study, the evaluations of the suggested shielding designs were conducted using MCNP code. The suggested door design and covering structures can shield the neutron efficiently, thus all evaluations of all conditions are satisfied within the public dose limits. From the Monte Carlo code simulation, Resin(Indoor type) and Tungsten(Outdoor type) were selected as the shielding door materials. From a comparative evaluation of the door thickness, In and Out door thickness was selected 50 cm.

  13. [Trial manufacture of a plunger shield for a disposable plastic syringe].

    Science.gov (United States)

    Murakami, Shigeki; Emoto, Takashi; Mori, Hiroshige; Fujita, Katsuhisa; Kubo, Naoki

    2008-08-20

    A syringe-type radiopharmaceutical being supplied by a manufacturer has a syringe shield and a plunger shield, whereas an in-hospital labeling radiopharmaceutical is administered by a disposable plastic syringe without the plunger shield. In cooperation with Nihon Medi-Physics Co. Ltd., we have produced a new experimental plunger shield for the disposable plastic syringe. In order to evaluate this shielding effect, we compared the leaked radiation doses of our plunger shield with those of the syringe-type radiopharmaceutical (Medi shield type). Our plunger shield has a lead plate of 21 mm in diameter and 3 mm thick. This shield is equipped with the plunger-end of a disposal plastic syringe. We sealed 99mTc solution into a plastic syringe (Terumo Co.) of 5 ml with our plunger shield and Medi shield type of 2 ml. We measured leaked radiation doses around syringes using fluorescent glass dosimeters (Dose Ace). The number of measure points was 18. The measured doses were converted to 70 microm dose equivalent at 740 MBq of radioactivity. The results of our plunger shield and the Medi shield type were as follows: 4-13 microSv/h and 3-14 microSv/h at shielding areas, 3-545 microSv/h and 6-97 microSv/h at non-shielding areas, 42-116 microSv/h and 88-165 microSv/h in the vicinity of the syringe shield, and 1071 microSv/h and 1243 microSv/h at the front of the needle. For dose rates of shielding areas around the syringe, the shielding effects were approximately the same as those of the Medi shield type. In conclusion, our plunger shield may be useful for reducing finger exposure during the injection of an in-hospital labeled radiopharmaceutical.

  14. Investigation of corrosion, water reaction, polonium evaporation and bismuth resource in liquid metal lead-bismuth technology

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Hideki; Takizuka, Takakazu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kitano, Teruaki [Mitsui Shipbuilding and Engineering Co. Ltd., Tokyo (Japan)

    2000-10-01

    Lead-bismuth is the first candidate material for liquid metal target find coolant of fueled blanket system in accelerator-driven system (ADS) studied at JAERI. Advantages of the lead-bismuth utilization are non-active material, very low capture cross section, low melting point of 125degC and high boiling point of 1670degC, and beside coolant void reactivity become negative. But problems are due to the high corrosivity to most of the structural materials and the corrosive data are scarcity. In this report, corrosivity, reaction with water, thermal-hydraulics, chemical toxicity etc. are studied by investigating some facilities utilized and researched really for lead or lead-bismuth. And, furthermore, polonium evaporation rate and bismuth resource are investigated. Main results obtained are as follows: (1) In a refinery, there are enough employment experience for liquid Pb-Bi in period of about 17 years and not corrosion for the thermal conductive materials (1Cr-0.5Mo steel) used under the condition of natural convection with temperature around 400degC. (2) In Russia, extensive experience in the use as Russian submarines and in R and D during about 50 years are available. And as a result, it will be able to lead approximately zero corrosion for Cr-Si materials by adjusting oxygen film with oxygen concentration control between 10{sup -7} to 10{sup -5}% mass. However, the corrosion data are not enough systematically collected involving them in radiation dose field. (3) In liquid-dropping experiment, it is shown that interaction between water and high temperature liquid Pb-Bi is reduced steeply with rising of atmosphere pressure. But, in order to design the second circuit removal model of ADS, the interaction should be evaluated by water continuous injection experiment. (4) Polonium forms PbPo in Pb-Bi, and the evaporation rate become less three factor than that of Po, and furthermore, the rate decreases in the atmosphere. The effects of Po on employee and environment

  15. Au Foil Activation Measurement and Simulation of the Concrete Neutron Shielding Ability for the Proposed New SANRAD Facility

    Science.gov (United States)

    Radebe, M. J.; Korochinsky, S.; Strydom, W. J.; De Beer, F. C.

    The purpose of this study was to measure the effective neutron shielding characteristics of the new shielding material designed and manufactured to be used for the construction of the new SANRAD facility at Necsa, South Africa, through Au foil activation as well as MCNP simulations. The shielding capability of the high density shielding material was investigated in the worst case region (the neutron beam axis) of the experimental chamber for two operational modes. The everyday operational mode includes the 15 cm thick poly crystalline Bismuth filter at room temperature (assumed) to filter gamma-rays and some neutron spectrum energies. The second mode, dynamic imaging, will be conducted without the Bi-filter. The objective was achieved through a foil activation measurement at the current SANRAD facility and MCNP calculations. Several Au foilswere imbedded at different thicknesses(two at each position) of shielding material up to 80 cm thick to track the attenuation of the neutron beam over distance within the shielding material. The neutron flux and subsequently the associated dose rates were calculated from the activation levels of the Au foils. The concrete shielding material was found to provide adequate shielding for all energies of neutrons emerging from beam port no-2 of the SAFARI-1 research reactorwithin a thickness of 40 cm of concrete.

  16. Bismuth( Ⅲ ) Salts: Green Catalysts for Organic Transformations

    Institute of Scientific and Technical Information of China (English)

    C. Le Roux

    2005-01-01

    @@ 1Introduction Bismuth, the heaviest stable element in the periodic table, stands out from other heavy elements (such as mercury, thallium and lead) due to its relatively non-toxic character which confers on bismuth the enviable status of being an eco-friendly element. Therefore, bismuth and its compounds hold considerable promise as useful catalysts for green chemistry. The research presented in this communication is devoted to the applications of bismuth( Ⅲ ) salts as catalysts for organic transformations.After some general comments about bismuth and a short presentation of the various applications of bismuth( Ⅲ ) salts in organic synthesis, this communication will focus on the works done in our research group during the last several years which deals mainly with electrophilic substitutions. When appropriate, some mechanistic details will be given.

  17. RadShield: semiautomated shielding design using a floor plan driven graphical user interface.

    Science.gov (United States)

    DeLorenzo, Matthew C; Wu, Dee H; Yang, Kai; Rutel, Isaac B

    2016-09-01

    The purpose of this study was to introduce and describe the development of RadShield, a Java-based graphical user interface (GUI), which provides a base design that uniquely performs thorough, spatially distributed calculations at many points and reports the maximum air-kerma rate and barrier thickness for each barrier pursuant to NCRP Report 147 methodology. Semiautomated shielding design calculations are validated by two approaches: a geometry-based approach and a manual approach. A series of geometry-based equations were derived giving the maximum air-kerma rate magnitude and location through a first derivative root finding approach. The second approach consisted of comparing RadShield results with those found by manual shielding design by an American Board of Radiology (ABR)-certified medical physicist for two clinical room situations: two adjacent catheterization labs, and a radiographic and fluoroscopic (R&F) exam room. RadShield's efficacy in finding the maximum air-kerma rate was compared against the geometry-based approach and the overall shielding recommendations by RadShield were compared against the medical physicist's shielding results. Percentage errors between the geometry-based approach and RadShield's approach in finding the magnitude and location of the maximum air-kerma rate was within 0.00124% and 14 mm. RadShield's barrier thickness calculations were found to be within 0.156 mm lead (Pb) and 0.150 mm lead (Pb) for the adjacent catheterization labs and R&F room examples, respectively. However, within the R&F room example, differences in locating the most sensitive calculation point on the floor plan for one of the barriers was not considered in the medical physicist's calculation and was revealed by the RadShield calculations. RadShield is shown to accurately find the maximum values of air-kerma rate and barrier thickness using NCRP Report 147 methodology. Visual inspection alone of the 2D X-ray exam distribution by a medical physicist may not

  18. Magnetic shielding structure optimization design for wireless power transmission coil

    Science.gov (United States)

    Dai, Zhongyu; Wang, Junhua; Long, Mengjiao; Huang, Hong; Sun, Mingui

    2017-09-01

    In order to improve the performance of the wireless power transmission (WPT) system, a novel design scheme with magnetic shielding structure on the WPT coil is presented in this paper. This new type of shielding structure has great advantages on magnetic flux leakage reduction and magnetic field concentration. On the basis of theoretical calculation of coil magnetic flux linkage and characteristic analysis as well as practical application feasibility consideration, a complete magnetic shielding structure was designed and the whole design procedure was represented in detail. The simulation results show that the coil with the designed shielding structure has the maximum energy transmission efficiency. Compared with the traditional shielding structure, the weight of the new design is significantly decreased by about 41%. Finally, according to the designed shielding structure, the corresponding experiment platform is built to verify the correctness and superiority of the proposed scheme.

  19. Genotoxic effects of bismuth (III oxide nanoparticles by comet assay

    Directory of Open Access Journals (Sweden)

    Reecep Liman

    2015-06-01

    Full Text Available Bismuth oxide is one of the important transition metal oxides and it has been intensively studied due to their peculiar characteristics (semiconductor band gap, high refractive index, high dielectric permittivity, high oxygen conductivity, resistivity, photoconductivity and photoluminescence etc.. Therefore, it is used such as microelectronics, sensor technology, optical coatings, transparent ceramic glass manufacturing, nanoenergetic gas generator, biosensor for DNA hybridization, potential immobilizing platforms for glucose oxidase and polyphenol oxidase, fuel cells, a additive in paints, an astringent in a variety of medical creams and topical ointments, and for the determination of heavy metal ions in drinking water, mineral water and urine. In addition this, Bismuth (III oxide nanoparticles (BONPs are favorable for the biomolecules adsorption than regular sized particles because of their greater advantages and novel characteristics (much higher specific surface, greater surface free energy, and good electrochemical stability etc.. Genotoxic effects of BONPs were investigated on the root cells of Allium cepa by Comet assay. A. cepa roots were treated with the aqueous dispersions of BONPs at 5 different concentrations (12.5, 25, 50, 75, and 100 ppm for 4 h. A significant increase in DNA damage was also observed at all concentrations of BONPs except 12.5 ppm by Comet assay. The results were also analyzed statistically by using SPSS for Windows; Duncan’s multiple range test was performed. These result indicate that BONPs exhibit genotoxic activity in A. cepa root meristematic cells.

  20. Synthesis and characterization of bismuth alkaline titanate powders

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Huerta, A.M., E-mail: atorresh@ipn.mx [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Dominguez-Crespo, M.A. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Hernandez-Perez, M.A. [ESIQIE, Metalurgia, Instituto Politecnico Nacional, Mexico, D. F (Mexico); Garcia-Zaleta, D.S. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Brachetti-Sibaja, S.B. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Instituto Tecnologico de Ciudad Madero, Av. 1o. de Mayo esq. Sor Juana Ines de la Cruz s/n Col. Los Mangos C.P.89440 Cd. Madero Tamaulipas (Mexico)

    2011-06-15

    In this work, samples of bismuth alkaline titanate, (K{sub 0.5}Na{sub 0.5}){sub (2-x/2)}Bi{sub (x/6)}TiO{sub 3}, (x = 0.05-0.75) have been prepared by conventional ceramic technique and molten salts. Metal oxides or carbonates powders were used as starting raw materials. The crystalline phase of the synthesized powders was identified by the X-ray diffraction (XRD) and particle morphology was characterized by scanning electron microscopy (SEM). Solid state reaction method was unsuccessful to obtain pellets. From XRD results, a rhombohedral structure was detected and the parameter lattice were estimated to be a = 5.5478 A and {alpha} = 59.48{sup o}. These parameters were used to refine the structure by Rietveld analysis. SEM results showed several morphologies. Apparently, bismuth is promoting the grain growth whose sizes vary from 30 nm to 180 nm It is expected that these materials can be utilized in practical applications as substitutes for lead zirconatetitanate (PZT)-based ceramics.

  1. Magnetic properties of the binary Nickel/Bismuth alloy

    Science.gov (United States)

    Keskin, Mustafa; Şarlı, Numan

    2017-09-01

    Magnetic properties of the binary Nickel/Bismuth alloy (Ni/Bi) are investigated within the effective field theory. The Ni/Bi alloy has been modeled that the rhombohedral Bi lattice is surrounded by the hexagonal Ni lattice. According to lattice locations, Bi atoms have two different magnetic properties. Bi1 atoms are in the center of the hexagonal Ni atoms (Ni/Bi1 single layer) and Bi2 atoms are between two Ni/Bi1 bilayers. The Ni, Bi1, Bi2 and Ni/Bi undergo a second-order phase transition from the ferromagnetic phase to paramagnetic phase at Tc = 1.14. The magnetizations of the Ni/Bi alloy are observed as Bi1 > Bi2 > Ni/Bi > Ni at T < Tc; hence the magnetization of the Bi1 is dominant and Ni is at least dominant. However, the total magnetization of the Ni/Bi alloy is close to magnetization of the Ni at T < Tc. The corcivities of the Ni, Bi1, Bi2 and Ni/Bi alloy are the same with each others, but the remanence magnetizations are different. Our theoretical results of M(T) and M(H) of the Ni/Bi alloy are in quantitatively good agreement with the some experimental results of binary Nickel/Bismuth systems.

  2. Light shielding apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Richard Dean; Thom, Robert Anthony

    2017-10-10

    A light shielding apparatus for blocking light from reaching an electronic device, the light shielding apparatus including left and right support assemblies, a cross member, and an opaque shroud. The support assemblies each include primary support structure, a mounting element for removably connecting the apparatus to the electronic device, and a support member depending from the primary support structure for retaining the apparatus in an upright orientation. The cross member couples the left and right support assemblies together and spaces them apart according to the size and shape of the electronic device. The shroud may be removably and adjustably connectable to the left and right support assemblies and configured to take a cylindrical dome shape so as to form a central space covered from above. The opaque shroud prevents light from entering the central space and contacting sensitive elements of the electronic device.

  3. Shielding calculations for SSC

    Energy Technology Data Exchange (ETDEWEB)

    Van Ginneken, A.

    1990-03-01

    Monte Carlo calculations of hadron and muon shielding for SSC are reviewed with emphasis on their application to radiation safety and environmental protection. Models and algorithms for simulation of hadronic and electromagnetic showers, and for production and transport of muons in the TeV regime are briefly discussed. Capabilities and limitations of these calculations are described and illustrated with a few examples. 12 refs., 3 figs.

  4. The antimicrobial effects and metabolomic footprinting of carboxyl-capped bismuth nanoparticles against Helicobacter pylori.

    Science.gov (United States)

    Nazari, P; Dowlatabadi-Bazaz, R; Mofid, M R; Pourmand, M R; Daryani, N E; Faramarzi, M A; Sepehrizadeh, Z; Shahverdi, A R

    2014-01-01

    Organic salts of bismuth are currently used as antimicrobial agents against Helicobacter pylori. This study evaluated the antibacterial effect of elemental bismuth nanoparticles (Bi NPs) using a serial agar dilution method for the first time against different clinical isolates and a standard strain of H. pylori. The Bi NPs were biologically prepared and purified by a recently described method and subjected to further characterization by infrared spectroscopy and anti-H. pylori evaluation. Infrared spectroscopy results showed the presence of carboxyl functional groups on the surface of biogenic Bi NPs. These biogenic nanoparticles showed good antibacterial activity against all tested H. pylori strains. The resulting MICs varied between 60 and 100 μg/ml for clinical isolates of H. pylori and H. pylori (ATCC 26695). The antibacterial effect of bismuth ions was also tested against all test strains. The antimicrobial effect of Bi ions was lower than antimicrobial effect of bismuth in the form of elemental NPs. The effect of Bi NPs on metabolomic footprinting of H. pylori was further evaluated by (1)H NMR spectroscopy. Exposure of H. pylori to an inhibitory concentration of Bi NPs (100 μg/ml) led to release of some metabolites such as acetate, formic acid, glutamate, valine, glycine, and uracil from bacteria into their supernatant. These findings confirm that these nanoparticles interfere with Krebs cycle, nucleotide, and amino acid metabolism and shows anti-H. pylori activity.

  5. Bismuth-embedded SBA-15 mesoporous silica for radioactive iodine capture and stable storage

    Science.gov (United States)

    Yang, Jae Hwan; Cho, Yong-Jun; Shin, Jin Myeong; Yim, Man-Sung

    2015-10-01

    Efficient capture and stable storage of the long-lived iodine-129 (129I), released as off-gas from nuclear fuel reprocessing, have been of significant concern in the waste management field. In this study, bismuth-embedded SBA-15 mesoporous silica was firstly applied for iodine capture and storage. SBA-15 was functionalized with thiol (-SH) groups, followed by bismuth adsorption with Bi-S bonding, which was thermally treated to form Bi2S3 within SBA-15. The bismuth-embedded SBA-15s demonstrated high iodine loading capacities (up to 540 mg-I/g-sorbent), which benefitted from high surface area and porosity of SBA-15 as well as the formation of thermodynamically stable BiI3 compound. Iodine physisorption was effectively suppressed due to the large pores present in SBA-15, resulting in chemisorption as a main mechanism for iodine confinement. Furthermore, a chemically durable iodine-bearing material was made with a facile post-sorption process, during which the iodine-incorporated phase was changed from BiI3 to chemically durable Bi5O7I. Thus, our results showed that both efficient capture and stabilization of 129I would be possible with the bismuth-embedded SBA-15, in contrast to other sorbents mainly focused on iodine capture.

  6. The heterogeneous anti-radiation shield for spacecraft*

    Science.gov (United States)

    Telegin, S. V.; Draganyuk, O. N.

    2016-04-01

    The paper deals with modeling of elemental composition and properties of heterogeneous layers in multilayered shields to protect spacecraft onboard equipment from radiation emitted by the natural Earth’s radiation belt. This radiation causes malfunctioning of semiconductor elements in electronic equipment and may result in a failure of the spacecraft as a whole. We consider four different shield designs and compare them to the most conventional radiation-protective material for spacecraft - aluminum. Out of light and heavy chemical elements we chose the materials with high reaction cross sections and low density. The mass attenuation coefficient of boron- containing compounds is 20% higher than that of aluminum. Heterogeneous shields consist of three layers: a glass cloth, borated material, and nickel. With a protective shield containing heavy metal the output bremsstrahlung can be reduced. The amount of gamma rays that succeed to penetrate the shield is 4 times less compared to aluminum. The shields under study have the thicknesses of 5.95 and 6.2 mm. A comparative analysis of homogeneous and multilayered protective coatings of the same chemical composition has been performed. A heterogeneous protective shield has been found to be advantageous in weight and shielding properties over its homogeneous counterparts and aluminum. The dose characteristics and transmittance were calculated by the Monte Carlo method. The results of our study lead us to conclude that a three-layer boron carbide shield provides the most effective protection from radiation. This shield ensures twice as low absorbed dose and 4 times less the number of penetrated gamma-ray photons compared to its aluminum analogue. Moreover, a heterogeneous shield will have a weight 10% lighter than aluminum, with the same attenuation coefficient of the electron flux. Such heterogeneous shields can be used to protect spacecraft launched to geostationary orbit. Furthermore, a protective boron-containing and

  7. Crack tip shielding and anti-shielding effects of parallel cracks for a superconductor slab under an electromagnetic force

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhi Wen; Zhou, You He [Ministry of Education, Singapore (China); Lee, Kang Yong [Yonsei University, Seoul (Korea, Republic of)

    2012-02-15

    In this letter, the shielding or anti-shielding effect is firstly applied to obtain the behavior of two parallel cracks in a two-dimensional type-II superconducting under electromagnetic force. Fracture analysis is performed by the finite element method and the magnetic behavior of superconductor is described by the critical state Bean model. The stress intensity factors at the crack tips can be obtained and discussed for decreasing field after zero-field cooling. The shielding or anti-shielding effect at the crack tips depend on the distance between two parallel cracks and the crack length. The results indicate that the shielding effects of the two parallel cracks increase when the distance between the two parallel cracks decreases. It can be also obtained that the superconductors with shorter cracks has more remarkable shielding effect than those with longer cracks.

  8. Cosmic Ray Interactions in Shielding Materials

    Energy Technology Data Exchange (ETDEWEB)

    Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Ankney, Austin S.; Orrell, John L.; Berguson, Timothy J.; Troy, Meredith D.

    2011-09-08

    This document provides a detailed study of materials used to shield against the hadronic particles from cosmic ray showers at Earth’s surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during transport for the MAJORANA collaboration. The materials suitable for cosmic-ray shield design are materials such as lead and iron that will stop the primary protons, and materials like polyethylene, borated polyethylene, concrete and water that will stop the induced neutrons. The interaction of the different cosmic-ray components at ground level (protons, neutrons, muons) with their wide energy range (from kilo-electron volts to giga-electron volts) is a complex calculation. Monte Carlo calculations have proven to be a suitable tool for the simulation of nucleon transport, including hadron interactions and radioactive isotope production. The industry standard Monte Carlo simulation tool, Geant4, was used for this study. The result of this study is the assertion that activation at Earth’s surface is a result of the neutronic and protonic components of the cosmic-ray shower. The best material to shield against these cosmic-ray components is iron, which has the best combination of primary shielding and minimal secondary neutron production.

  9. Advances in space radiation shielding codes

    Science.gov (United States)

    Wilson, John W.; Tripathi, Ram K.; Qualls, Garry D.; Cucinotta, Francis A.; Prael, Richard E.; Norbury, John W.; Heinbockel, John H.; Tweed, John; De Angelis, Giovanni

    2002-01-01

    Early space radiation shield code development relied on Monte Carlo methods and made important contributions to the space program. Monte Carlo methods have resorted to restricted one-dimensional problems leading to imperfect representation of appropriate boundary conditions. Even so, intensive computational requirements resulted and shield evaluation was made near the end of the design process. Resolving shielding issues usually had a negative impact on the design. Improved spacecraft shield design requires early entry of radiation constraints into the design process to maximize performance and minimize costs. As a result, we have been investigating high-speed computational procedures to allow shield analysis from the preliminary concept to the final design. For the last few decades, we have pursued deterministic solutions of the Boltzmann equation allowing field mapping within the International Space Station (ISS) in tens of minutes using standard Finite Element Method (FEM) geometry common to engineering design methods. A single ray trace in such geometry requires 14 milliseconds and limits application of Monte Carlo methods to such engineering models. A potential means of improving the Monte Carlo efficiency in coupling to spacecraft geometry is given.

  10. Asymmetric Electrostatic Radiation Shielding for Spacecraft

    Science.gov (United States)

    Metzger, Philip T.; Youngquist, Robert C.; Lane, John E.

    2005-01-01

    A paper describes the types, sources, and adverse effects of energetic-particle radiation in interplanetary space, and explores a concept of using asymmetric electrostatic shielding to reduce the amount of such radiation impinging on spacecraft. Typically, such shielding would include a system of multiple inflatable, electrically conductive spheres deployed in clusters in the vicinity of a spacecraft on lightweight structures that would maintain the spheres in a predetermined multipole geometry. High-voltage generators would maintain the spheres at potential differences chosen in conjunction with the multipole geometry so that the resulting multipole field would gradually divert approaching energetic atomic nuclei from a central region occupied by the spacecraft. The spheres nearest the center would be the most positive, so as to repel the positively charged impinging nuclei from the center. At the same time, the monopole potential of the overall spacecraft-and-shielding system would be made negative so as to repel thermal electrons. The paper presents results of computational simulations of energetic-particle trajectories and shield efficiency for a trial system of 21 spheres arranged in three clusters in an overall linear quadrupole configuration. Further development would be necessary to make this shielding concept practical.

  11. Nonproportionality in the scintillation light yield of bismuth germanate

    CERN Document Server

    Gentile, T R; Breuer, H; Chupp, T E; Coakley, K J; Cooper, R L; Nico, J S; O'Neill, B

    2015-01-01

    We present measurements of nonproportionality in the scintillation light yield of bismuth germanate (BGO) for gamma-rays with energies between 6 keV and 662 keV. The scintillation light was read out by avalanche photodiodes (APDs) with both the BGO crystals and APDs operated at a temperature of approximately 90 K. Data were obtained using radioisotope sources to illuminate both a single BGO crystal in a small test cryostat and a 12-element detector in a neutron radiative beta-decay experiment. In addition one datum was obtained in a 4.6 T magnetic field based on the bismuth K x-ray escape peak produced by a continuum of background gamma rays in this apparatus. These measurements and comparison to prior results were motivated by an experiment to study the radiative decay mode of the free neutron. The combination of data taken under different conditions yields a reasonably consistent picture for BGO nonproportionality that should be useful for researchers employing BGO detectors at low gamma ray energies.

  12. New Bismuth-Substituted Hydroxyapatite Nanoparticles for Bone Tissue Engineering

    Science.gov (United States)

    Ciobanu, Gabriela; Bargan, Ana Maria; Luca, Constantin

    2015-11-01

    New bismuth-substituted hydroxyapatite [Ca10- x Bi x (PO4)6(OH)2 where x = 0-2.5] nanoparticles were synthesized by the co-precipitation method from aqueous solutions. The structural properties of the samples were analyzed by scanning electron microscopy coupled with x-ray analysis, x-ray powder diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller surface area analysis. The results confirm that bismuth ions have been incorporated into the hydroxyapatite lattice. The prepared nanocrystalline powders consisted of hydroxyapatite as single phase with hexagonal structure, crystal sizes smaller than 60 nm and (Bi + Ca)/P atomic ratio of around 1.67. The hydroxyapatite samples doped with Bi have mesoporous textures with pores size of around 2 nm and specific surface area in the range of 12-25 m2/g. The Bi-substituted hydroxyapatite powders are more effective against Gram-negative Escherichia coli bacteria than Gram-positive Staphylococcus aureus bacteria.

  13. Magnetic anisotropies in ultrathin bismuth iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Elena, E-mail: popova@physique.uvsq.fr [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Franco Galeano, Andres Felipe [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Deb, Marwan [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Warot-Fonrose, Bénédicte [Centre d' Elaboration de Matériaux et d' Etudes Structurales (CEMES), CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France); Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS–Universidad de Zaragoza (Spain); Kachkachi, Hamid [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Gendron, François [Institut des NanoSciences de Paris (INSP), CNRS/Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, Boîte courrier 840, 75252 Paris Cedex 05 (France); Ott, Frédéric [Laboratoire Léon Brillouin (LLB), CNRS/CEA, Bâtiment 563, CEA Saclay, 91191 Gif sur Yvette Cedex (France); and others

    2013-06-15

    Ultrathin bismuth iron garnet Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi{sub 3}Fe{sub 5}O{sub 12} films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi{sub 3}Fe{sub 5}O{sub 12} were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed.

  14. Factors affecting bismuth vanadate photoelectrochemical performance

    OpenAIRE

    Sinclair, Timothy S.; Hunter, Bryan M.; Winkler, Jay R.; Gray, Harry B.; Müller, Astrid M.

    2015-01-01

    Bismuth vanadate is a promising photoanode material, but recent reports on undoped BiVO_4 without sublayers and co-catalysts showed large variations in photocurrent generation. We addressed this issue by correlating photoelectrochemical performance with physical properties. We devised a novel anodic electrodeposition procedure with iodide added to the aqueous plating bath, which allowed us to prepare BiVO_4 photoanodes with virtually identical thicknesses but different morphologies, and we co...

  15. Electrocatalytic activity of bismuth doped silver electrodes

    CERN Document Server

    Amjad, M

    2002-01-01

    Investigation of redox reactions on silver, and bismuth doped silver electrodes in aqueous KOH solutions, by using potentiostatic steady-state polarization technique, has been carried out. The redox wave potential and current displacements along with multiplicity of the latter have been examined. These electrodes were employed for the oxidation of organic molecules such as ethylamine in alkaline media. Subsequently, these electrodes were ranked with respect to their activity for the redox reactions. (author)

  16. Efficient enhancement of bismuth NIR luminescence by aluminum and its mechanism in bismuth doped germanate laser glass

    DEFF Research Database (Denmark)

    Wang, L.P.; Tan, L.L.; Yue, Yuanzheng

    2016-01-01

    on how to improve the luminescence efficiency. Here, we demonstrate that addition of aluminum can enhance the bismuth near-infrared luminescence by more than 10 000 times, which is right followed by the discussion on the mechanism on why this can happen. We believe this work can be helpful for designing...... bismuth-doped multiple component laser glasses with high efficiency. In addition, because of high susceptibility of bismuth to local field change, it can be used as probe ion to envision glass structures. Using bismuth as a luminescent structural probe, we can see the modifier ions of Bi...

  17. Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator.

    Science.gov (United States)

    Babicheva, Viktoriia E; Zhukovsky, Sergei V; Lavrinenko, Andrei V

    2014-11-17

    We propose new designs of plasmonic modulators, which can be used for dynamic signal switching in photonic integrated circuits. We study performance of a plasmonic waveguide modulator with bismuth ferrite as a tunable material. The bismuth ferrite core is sandwiched between metal plates (metal-insulator-metal configuration), which also serve as electrodes. The core changes its refractive index by means of partial in-plane to out-of-plane reorientation of ferroelectric domains in bismuth ferrite under applied voltage. As a result, guided modes change their propagation constant and absorption coefficient, allowing light modulation in both phase and amplitude control schemes. Due to high field confinement between the metal layers, existence of mode cut-offs for certain values of the core thickness, and near-zero material losses in bismuth ferrite, efficient modulation performance is achieved. For the phase control scheme, the π phase shift is provided by a 0.8-μm long device with propagation losses 0.29 dB/μm. For the amplitude control scheme, up to 38 dB/μm extinction ratio with 1.2 dB/μm propagation loss is predicted.

  18. Preparation of Bismuth Oxide Photocatalyst and Its Application in White-light LEDs

    Directory of Open Access Journals (Sweden)

    Yen-Chang Chu

    2013-01-01

    Full Text Available Bismuth oxide photocatalysts were synthesized and coated on the front surface of phosphor-converted white light-emitting diodes to produce a safe and environmentally benign lighting source. Bismuth oxide photocatalyst powders were synthesized with a spray pyrolysis method at 500°C, 600°C, 700°C, and 800°C. Using the absorption spectrum in the blue and UV regions of the bismuth oxide photocatalysts, the blue light and UV leakage problems of phosphor-converted white LEDs can be significantly reduced. The experimental results showed that bismuth oxide photocatalyst synthesized at 700°C exhibited the most superior spectrum inhibiting ability. The suppressed ratio reached 52.33% in the blue and UV regions from 360 to 420 nm. Related colorimetric parameters and the photocatalyst decomposition ability of fabricated white-light LEDs were tested. The CIE chromaticity coordinates (x,y were (0.349, 0.393, and the correlated color temperature was 4991 K. In addition, the coating layer of photocatalyst can act as an air purifier and diffuser to reduce glare. A value of 66.2±0.60 ppmv of molecular formaldehyde gas can be decomposed in 120 mins.

  19. Light-Induced Surface Reactions at the Bismuth Vanadate/Potassium Phosphate Interface.

    Science.gov (United States)

    Favaro, Marco; Abdi, Fatwa F; Lamers, Marlene; Crumlin, Ethan J; Liu, Zhi; van de Krol, Roel; Starr, David E

    2017-09-18

    Bismuth vanadate has recently drawn significant research attention as a light-absorbing photoanode due to its performance for photoelectrochemical water splitting. In this study, we use in situ ambient pressure X-ray photoelectron spectroscopy with "tender" X-rays (4.0 keV) to investigate a polycrystalline bismuth vanadate (BiVO4) electrode in contact with an aqueous potassium phosphate (KPi) solution at open circuit potential under both dark and light conditions. This is facilitated by the creation of a 25 to 30 nm thick electrolyte layer using the "dip-and-pull" method. We observe that under illumination bismuth phosphate forms on the BiVO4 surface leading to an increase of the surface negative charge. The bismuth phosphate layer may act to passivate surface states observed in photoelectrochemical measurements. The repulsive interaction between the negatively charged surface under illumination and the phosphate ions in solution causes a shift in the distribution of ions in the thin aqueous electrolyte film, which is observed as an increase in their photoelectron signals. Interestingly, we find that such changes at the BiVO4/KPi electrolyte interface are reversible upon returning to dark conditions. By measuring the oxygen 1s photoelectron peak intensities from the phosphate ions and liquid water as a function of time under dark and light conditions, we determine the time scales for the forward and reverse reactions. Our results provide direct evidence for light-induced chemical modification of the BiVO4/KPi electrolyte interface.

  20. Electronics Shielding and Reliability Design Tools

    Science.gov (United States)

    Wilson, John W.; ONeill, P. M.; Zang, Thomas A., Jr.; Pandolf, John E.; Koontz, Steven L.; Boeder, P.; Reddell, B.; Pankop, C.

    2006-01-01

    It is well known that electronics placement in large-scale human-rated systems provides opportunity to optimize electronics shielding through materials choice and geometric arrangement. For example, several hundred single event upsets (SEUs) occur within the Shuttle avionic computers during a typical mission. An order of magnitude larger SEU rate would occur without careful placement in the Shuttle design. These results used basic physics models (linear energy transfer (LET), track structure, Auger recombination) combined with limited SEU cross section measurements allowing accurate evaluation of target fragment contributions to Shuttle avionics memory upsets. Electronics shielding design on human-rated systems provides opportunity to minimize radiation impact on critical and non-critical electronic systems. Implementation of shielding design tools requires adequate methods for evaluation of design layouts, guiding qualification testing, and an adequate follow-up on final design evaluation including results from a systems/device testing program tailored to meet design requirements.

  1. Shielding in Mental Health Hospitals

    Directory of Open Access Journals (Sweden)

    Espen W. Haugom

    2016-02-01

    Full Text Available Shielding is defined as the confinement of patients to a single room or a separate unit/area inside the ward, accompanied by a member of staff. It is understood as both a treatment and a control. The purpose of this study is to examine how staff in psychiatric hospitals describe and assess shielding. This qualitative study uses a descriptive and exploratory design with an inductive approach. The material was acquired through the Acute Network (in Psychiatry nationwide shielding project. Data collection was carried out by the staff, who described the shielding procedure on a semi-structured form. The analysis was inspired by Graneheim and Lundman’s qualitative content analysis. Shielding has been described as an ambiguous practice, that is, shielding can be understood in several ways. There is a clear tension between shielding as a control and shielding as a treatment, with control being described as more important. The important therapeutic elements of shielding have also been mentioned, and shielding involves isolation to different degrees.

  2. Heat-Pipe Bismuth Laser; Examination of Laser Action at 4722A in Bismuth Vapor

    Science.gov (United States)

    1976-11-01

    transitions in other atomic vapors. 13. MODELING OF THE INITIAL BREAKDOWN PROCESS During the initial nanosecond after the fast thyratron switch closes suddenly...lasers computer modeling , laser kin etics bismuth vapor pressure and composition excitation cross sections bismuth dim ers e8ifn.eividienibbek 2Q...P3 / 2 " p $3/4 transi- 3/4 3/2 tion probability is at least a factor of 20 too low. Continuation of the computer modeling begun in this study could

  3. X-Band Microwave Reflection Properties of Samarium/Bismuth-Substituted Barium Lanthanum Titanate Ceramics

    Science.gov (United States)

    Bahel, Shalini; Pubby, Kunal; Narang, Sukhleen Bindra

    2017-01-01

    Samarium/bismuth-substituted barium lanthanum titanate ceramics with chemical composition Ba4 (La_{1 - y - z} Smy Biz )_{9.33} Ti_{18} O_{54} (y = 0.5, 0.7; z = 0.05, 0.10, 0.15), intended as microwave reflecting materials, have been investigated in microwave X-band (8.2 GHz to 12.4 GHz) and the effect of substitution on their dielectric properties, i.e., dielectric constant and dielectric loss tangent, has been studied by vector network analyzer. Dielectric analysis showed that the dielectric constant increased with increasing samarium as well as bismuth content. Dielectric relaxation was observed for all samples in the scanned frequency range. Microwave reflection and transmission analysis of ceramic pellets of thickness 4 mm was carried out using two methods, i.e., open- and short-circuit approach, both indicating very high values of reflected power and very low values of transmitted power for all the doped materials in comparison with the base composition. The doped compositions are therefore potential microwave shielding materials for use in anechoic chambers, microwave laboratories, and radar equipment. Double-layer reflectors are also proposed, having better reflection properties (˜99% reflection) compared with single-layer reflectors.

  4. X-Band Microwave Reflection Properties of Samarium/Bismuth-Substituted Barium Lanthanum Titanate Ceramics

    Science.gov (United States)

    Bahel, Shalini; Pubby, Kunal; Narang, Sukhleen Bindra

    2017-03-01

    Samarium/bismuth-substituted barium lanthanum titanate ceramics with chemical composition Ba4 (La_{1 - y - z} Smy Biz )_{9.33} Ti_{18} O_{54} ( y = 0.5, 0.7; z = 0.05, 0.10, 0.15), intended as microwave reflecting materials, have been investigated in microwave X-band (8.2 GHz to 12.4 GHz) and the effect of substitution on their dielectric properties, i.e., dielectric constant and dielectric loss tangent, has been studied by vector network analyzer. Dielectric analysis showed that the dielectric constant increased with increasing samarium as well as bismuth content. Dielectric relaxation was observed for all samples in the scanned frequency range. Microwave reflection and transmission analysis of ceramic pellets of thickness 4 mm was carried out using two methods, i.e., open- and short-circuit approach, both indicating very high values of reflected power and very low values of transmitted power for all the doped materials in comparison with the base composition. The doped compositions are therefore potential microwave shielding materials for use in anechoic chambers, microwave laboratories, and radar equipment. Double-layer reflectors are also proposed, having better reflection properties (˜99% reflection) compared with single-layer reflectors.

  5. Preliminary Thermal Design of Cryogenic Radiation Shielding

    Science.gov (United States)

    Li, Xiaoyi; Mustafi, Shuvo; Boutte, Alvin

    2015-01-01

    Cryogenic Hydrogen Radiation Shielding (CHRS) is the most mass efficient material radiation shielding strategy for human spaceflight beyond low Earth orbit (LEO). Future human space flight, mission beyond LEO could exceed one year in duration. Previous radiation studies showed that in order to protect the astronauts from space radiation with an annual allowable radiation dose less than 500 mSv, 140 kgm2 of polyethylene is necessary. For a typical crew module that is 4 meter in diameter and 8 meter in length. The mass of polyethylene radiation shielding required would be more than 17,500 kg. The same radiation study found that the required hydrogen shielding for the same allowable radiation dose is 40 kgm2, and the mass of hydrogen required would be 5, 000 kg. Cryogenic hydrogen has higher densities and can be stored in relatively small containment vessels. However, the CHRS system needs a sophisticated thermal system which prevents the cryogenic hydrogen from evaporating during the mission. This study designed a cryogenic thermal system that protects the CHRS from hydrogen evaporation for one to up to three year mission. The design also includes a ground based cooling system that can subcool and freeze liquid hydrogen. The final results show that the CHRS with its required thermal protection system is nearly half of the mass of polyethylene radiation shielding.

  6. Electromagnetic shielding mats: facts and fiction.

    Science.gov (United States)

    Leitgeb, N; Cech, R

    2007-01-01

    The use of electricity is accompanied by electric and magnetic fields which, intended or not, became a part of our environment. However, fear from environmental electromagnetic fields (EMFs) is widespread and so is business with fear. A number of more or less serious products including miracle products are placed on the market partly at excessive costs. By numerical simulation the efficiency of electromagnetic shielding mats was investigated and claims of manufacturers and their cited expert opinions checked. It could be shown that such products do not fulfil the justified expectations of customers, neither in the extremely low frequency (ELF) nor in the radiofrequency (RF) range. On the contrary, these mats usually make things even worse. The connection to ground, if available, might increase the belief on shielding efficiency, but in fact it even enhances fields instead of improving shielding. The electric conductivity of the mat material plays a minor role in the ELF range and enhances field increase in the RF range. It can not explain the enormous price differences. It could be shown that positive reports can be explained by result picking and exceptional arrangements of selected field sources. Overall, the investigation showed that manufacturer's claims about the shielding effectiveness are misleading and fool the customers about the real situation. Therefore, acquisition and use of electromagnetic shielding mats must be strongly discouraged.

  7. Gravity Scaling of a Power Reactor Water Shield

    Science.gov (United States)

    Reid, Robert S.; Pearson, J. Boise

    2008-01-01

    Water based reactor shielding is being considered as an affordable option for use on initial lunar surface power systems. Heat dissipation in the shield from nuclear sources must be rejected by an auxiliary thermal hydraulic cooling system. The mechanism for transferring heat through the shield is natural convection between the core surface and an array of thermosyphon radiator elements. Natural convection in a 100 kWt lunar surface reactor shield design has been previously evaluated at lower power levels (Pearson, 2007). The current baseline assumes that 5.5 kW are dissipated in the water shield, the preponderance on the core surface, but with some volumetric heating in the naturally circulating water as well. This power is rejected by a radiator located above the shield with a surface temperature of 370 K. A similarity analysis on a water-based reactor shield is presented examining the effect of gravity on free convection between a radiation shield inner vessel and a radiation shield outer vessel boundaries. Two approaches established similarity: 1) direct scaling of Rayleigh number equates gravity-surface heat flux products, 2) temperature difference between the wall and thermal boundary layer held constant on Earth and the Moon. Nussult number for natural convection (laminar and turbulent) is assumed of form Nu = CRa(sup n). These combined results estimate similarity conditions under Earth and Lunar gravities. The influence of reduced gravity on the performance of thermosyphon heat pipes is also examined.

  8. A contribution to shielding effectiveness analysis of shielded tents

    Directory of Open Access Journals (Sweden)

    Vranić Zoran M.

    2004-01-01

    Full Text Available An analysis of shielding effectiveness (SE of the shielded tents made of the metallised fabrics is given. First, two electromagnetic characteristic fundamental for coupling through electrically thin shield, the skin depth break frequency and the surface resistance or transfer impedance, is defined and analyzed. Then, the transfer function and the SE are analyzed regarding to the frequency range of interest to the Electromagnetic Compatibility (EMC Community.

  9. Justification for Shielded Receiver Tube Additional Lead Shielding

    Energy Technology Data Exchange (ETDEWEB)

    BOGER, R.M.

    2000-04-11

    In order to reduce high radiation dose rates encountered when core sampling some radioactive waste tanks the addition of 240 lbs. of lead shielding is being considered to the shielded receiver tube on core sample trucks No.1, No.3 and No.4. The lead shielding is 4 inch diameter x 1/2 inch thick half rounds that have been installed around the SR tube over its' full length. Using three unreleased but independently reviewed structural analyses HNF-6018 justifies the addition of the lead shielding.

  10. 铋含量对铅铋合金表面张力的影响分析%Influence of Bismuth Content on Surface Tension of Lead-bismuth Alloy

    Institute of Scientific and Technical Information of China (English)

    王龙; 徐敬尧; 徐刚; 刘少军; 黄群英

    2013-01-01

    Liquid lead-bismuth alloy has been considered as the potential candidates for the liquid spallation targets and the coolant of accelerator driven sub-critical system (ADS ) . Surface tension is one of the important thermal and physical properties parameters of lead-bismuth alloy , and temperature and chemical composition are important influence factors of surface tension . In this paper , the surface tension of liquid lead-bismuth alloy was measured by sessile drop (SD ) method . The results indicate that the surface tension of lead-bismuth alloy firstly increases and then decreases with the increase of the test temperature ,and the surface tension for low test temperature is significantly small .At the same temperature ,the surface tension of lead-bismuth alloy decreases with the increase of bismuth content , and segregation of bismuth onto the surface of molten lead-bismuth alloy is a key factor leading to the smaller surface tension .T he results of this study provide basic reference for composition optimization of lead-bismuth alloy ,w hich is of great significance for the development of spallation targets and the coolant materials of accelerated driven sub-critical system .%液态铅铋合金是加速器驱动的次临界系统(ADS )中散裂靶兼冷却剂的主要候选材料。表面张力是液态铅铋合金的重要热物性参数之一,而温度和化学组成是影响表面张力的关键因素。本文采用静滴法测量了5种不同成分铅铋合金的表面张力。实验结果显示:在测试温度范围内,铅铋合金的表面张力均随温度的升高先增大后减小,且在低温区表面张力非常小;相同温度下,铅铋合金的表面张力随Bi含量的增大逐渐降低,其中Bi的表面偏聚是导致其变小的重要因素之一。本研究结果为铅铋合金的成分优化提供了基本参考,对发展ADS散裂靶和冷却剂材料具有重要意义。

  11. Carbohydrate based materials for gamma radiation shielding

    Science.gov (United States)

    Tabbakh, F.; Babaee, V.; Naghsh-Nezhad, Z.

    2015-05-01

    Due to the limitation in using lead as a shielding material for its toxic properties and limitation in abundance, price or non-flexibility of other commonly used materials, finding new shielding materials and compounds is strongly required. In this conceptual study carbohydrate based compounds were considered as new shielding materials. The simulation of radiation attenuation is performed using MCNP and Geant4 with a good agreement in the results. It is found that, the thickness of 2 mm of the proposed compound may reduce up to 5% and 50% of 1 MeV and 35 keV gamma-rays respectively in comparison with 15% and 100% for the same thickness of lead.

  12. Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    Power, S.; Mirza, M.; Thakorlal, A.; Ganai, B.; Gavagan, L. D.; Given, M. F.; Lee, M. J., E-mail: mlee@rcsi.ie [Beaumont Hospital, Imaging and Interventional Radiology Department (Ireland)

    2015-06-15

    PurposeThis prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures.Materials and MethodsA commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated.ResultsTLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142).ConclusionInitial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator’s body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.

  13. The axion shield

    CERN Document Server

    Andrianov, A A; Mescia, F; Renau, A

    2010-01-01

    We investigate the propagation of a charged particle in a spatially constant, but time dependent, pseudoscalar background. Physically this pseudoscalar background could be provided by a relic axion density. The background leads to an explicit breaking of Lorentz invariance; as a consequence the process p-> p gamma is possible and the background acts as a shield against extremely energetic cosmic rays, an effect somewhat similar to the GZK cut-off effect. The effect is model independent and can be computed exactly. The hypothetical detection of the photons radiated via this mechanism would provide an indirect way of verifying the cosmological relevance of axions.

  14. Self-Shielding Of Transmission Lines

    Energy Technology Data Exchange (ETDEWEB)

    Christodoulou, Christos [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-03-01

    The use of shielding to contend with noise or harmful EMI/EMR energy is not a new concept. An inevitable trade that must be made for shielding is physical space and weight. Space was often not as much of a painful design trade in older larger systems as they are in today’s smaller systems. Today we are packing in an exponentially growing number of functionality within the same or smaller volumes. As systems become smaller and space within systems become more restricted, the implementation of shielding becomes more problematic. Often, space that was used to design a more mechanically robust component must be used for shielding. As the system gets smaller and space is at more of a premium, the trades starts to result in defects, designs with inadequate margin in other performance areas, and designs that are sensitive to manufacturing variability. With these challenges in mind, it would be ideal to maximize attenuation of harmful fields as they inevitably couple onto transmission lines without the use of traditional shielding. Dr. Tom Van Doren proposed a design concept for transmission lines to a class of engineers while visiting New Mexico. This design concept works by maximizing Electric field (E) and Magnetic Field (H) field containment between operating transmission lines to achieve what he called “Self-Shielding”. By making the geometric centroid of the outgoing current coincident with the return current, maximum field containment is achieved. The reciprocal should be true as well, resulting in greater attenuation of incident fields. Figure’s 1(a)-1(b) are examples of designs where the current centroids are coincident. Coax cables are good examples of transmission lines with co-located centroids but they demonstrate excellent field attenuation for other reasons and can’t be used to test this design concept. Figure 1(b) is a flex circuit design that demonstrate the implementation of self-shielding vs a standard conductor layout.

  15. Li3PO4 Matrix Enables a Long Cycle Life and High Energy Efficiency Bismuth-Based Battery.

    Science.gov (United States)

    Sun, Chuan-Fu; Hu, Junkai; Wang, Peng; Cheng, Xi-Yuan; Lee, Sang Bok; Wang, YuHuang

    2016-09-14

    Bismuth is a lithium-ion battery anode material that can operate at an equilibrium potential higher than graphite and provide a capacity twice as high as that of Li4Ti5O12, making it intrinsically free from lithium plating that may cause catastrophic battery failure. However, the potential of bismuth is hampered by its inferior cyclability (limited to tens of cycles). Here, we propose an "ion conductive solid-state matrix" approach to address this issue. By homogeneously confining bismuth nanoparticles in a solid-state γ-Li3PO4 matrix that is electrochemically formed in situ, the resulting composite anode exhibits a reversible capacity of 280 mA hours per gram (mA h/g) at a rate of 100 mA/g and a record cyclability among bismuth-based anodes up to 500 cycles with a capacity decay rate of merely 0.071% per cycle. We further show that full-cell batteries fabricated from this composite anode and commercial LiFePO4 cathode deliver a stable cell voltage of ∼2.5 V and remarkable energy efficiency up to 86.3%, on par with practical batteries (80-90%). This work paves a way for harnessing bismuth-based battery chemistry for the design of high capacity, safer lithium-ion batteries to meet demanding applications such as electric vehicles.

  16. Structural relaxation in bismuth and lead borate glasses

    Science.gov (United States)

    Bajaj, Anu; Khanna, Atul

    2012-06-01

    Bismuth and lead borate glasses were prepared by melt quench technique. Effects of heat treatment on the density and thermal properties of bismuth and lead borate glasses was studied by annealing the glasses at 350°C for 500 h. Density of all bismuth borate glasses increases by about 0.5-0.7% with annealing and the effect is more in glasses with higher Bi2O3 concentration. In bismuth borate glasses with 50 and 55 mol % Bi2O3 we found an extraordinary large increase of Tg by 15°C after thermal annealing. All bismuth borate glasses remained completely clear and transparent on annealing. Lead borate glasses become cloudy on thermal annealing indicating occurrence of phase separation in these glasses.

  17. Dosimetric evaluation of eye lense shieldings in computed tomography examination - measurements and Monte Carlo simulations; Dosimetrische Evaluation von Augenlinsen-Protektoren in der Computertomographie - Messungen und Monte-Carlo-Simulationen

    Energy Technology Data Exchange (ETDEWEB)

    Wulff, J.; Zink, K. [Inst. fuer Medizinische Physik und Strahlenschutz, Fachhochschule Giessen-Friedberg (Germany); Keil, B.; Heverhagen, J.T.; Klose, K.J. [Klinik fuer Strahlendiagnostik, Medizinisches Zentrum fuer Radiologie, Univ. Marburg (Germany); Auvanis, D. [Inst. fuer Medizinische Physik und Strahlenschutz, Fachhochschule Giessen-Friedberg (Germany); Klinik fuer Strahlendiagnostik, Medizinisches Zentrum fuer Radiologie, Univ. Marburg (Germany)

    2008-07-01

    The present study aims at the investigation of eye lens shielding of different composition for the use in computed tomography examinations. Measurements with thermo-luminescent dosimeters and a simple cylindrical waterfilled phantom were performed as well as Monte Carlo simulations with an equivalent geometry. Besides conventional shielding made of Bismuth coated latex, a new shielding with a mixture of metallic components was analyzed. This new material leads to an increased dose reduction compared to the Bismuth shielding. Measured and Monte Carlo simulated dose reductions are in good agreement and amount to 34% for the Bismuth shielding and 46% for the new material. For simulations the EGSnrc code system was used and a new application CTDOSPP was developed for the simulation of the computed tomography examination. The investigations show that a satisfying agreement between simulation and measurement with the chosen geometries of this study could only be achieved, when transport of secondary electrons was accounted for in the simulation. The amount of scattered radiation due to the protector by fluorescent photons was analyzed and is larger for the new material due to the smaller atomic number of the metallic components. (orig.)

  18. New Toroid shielding design

    CERN Multimedia

    Hedberg V

    On the 15th of June 2001 the EB approved a new conceptual design for the toroid shield. In the old design, shown in the left part of the figure above, the moderator part of the shielding (JTV) was situated both in the warm and cold areas of the forward toroid. It consisted both of rings of polyethylene and hundreds of blocks of polyethylene (or an epoxy resin) inside the toroid vacuum vessel. In the new design, shown to the right in the figure above, only the rings remain inside the toroid. To compensate for the loss of moderator in the toroid, the copper plug (JTT) has been reduced in radius so that a layer of borated polyethylene can be placed around it (see figure below). The new design gives significant cost-savings and is easier to produce in the tight time schedule of the forward toroid. Since the amount of copper is reduced the weight that has to be carried by the toroid is also reduced. Outgassing into the toroid vacuum was a potential problem in the old design and this is now avoided. The main ...

  19. Bismuth(III) dialkyldithiophosphates: Facile single source precursors for the preparation of bismuth sulfide nanorods and bismuth phosphate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Biswal, Jasmine B. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India); Garje, Shivram S., E-mail: ssgarje@chem.mu.ac.in [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India); Nuwad, Jitendra; Pillai, C.G.S. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2013-08-15

    Two different phase pure materials (Bi{sub 2}S{sub 3} and Bi{sub 2}P{sub 4}O{sub 13}) have been prepared under different conditions using the same single source precursors. Solvothermal decomposition of the complexes, Bi(S{sub 2}P(OR){sub 2}){sub 3} [where, R=Methyl (Me) (1), Ethyl (Et) (2), n-Propyl (Pr{sup n}) (3) and iso-Propyl (Pr{sup i}) (4)] in ethylene glycol gave orthorhombic bismuth sulfide nanorods, whereas aerosol assisted chemical vapor deposition (AACVD) of the same precursors deposited monoclinic bismuth tetraphosphate (Bi{sub 2}P{sub 4}O{sub 13}) thin films on glass substrates. Surface study of the thin films using SEM illustrated the formation of variety of nanoscale morphologies (spherical-, wire-, pendent-, doughnut- and flower-like) at different temperatures. AFM studies were carried out to evaluate quality of the films in terms of uniformity and roughness. Thin films of average roughness as low as 1.4 nm were deposited using these precursors. Photoluminescence studies of Bi{sub 2}P{sub 4}O{sub 13} thin films were also carried out. - Graphical abstract: Solvothermal decomposition of bismuth(III) dialkyldithiophosphates in ethylene glycol gave Bi{sub 2}S{sub 3} nanoparticles, whereas aerosol assisted chemical vapor deposition of these single source precursors deposited Bi{sub 2}P{sub 4}O{sub 13} thin films. Display Omitted - Highlights: • Preparation of phase pure orthorhombic Bi{sub 2}S{sub 3} nanorods and monoclinic Bi{sub 2}P{sub 4}O{sub 13} thin films. • Use of single source precursors for deposition of bismuth phosphate thin films. • Use of solvothermal decomposition and AACVD methods. • Morphology controlled synthesis of Bi{sub 2}P{sub 4}O{sub 13} thin films. • Bi{sub 2}S{sub 3} nanorods and Bi{sub 2}P{sub 4}O{sub 13} thin films using same single source precursors.

  20. The value of thyroid shielding in intraoral radiography

    Science.gov (United States)

    Hazenoot, Bart; Sanderink, Gerard C H; Berkhout, W Erwin R

    2016-01-01

    Objectives: To evaluate the utility of the application of a thyroid shield in intraoral radiography when using rectangular collimation. Methods: Experimental data were obtained by measuring the absorbed dose at the position of the thyroid gland in a RANDO® (The Phantom Laboratory, Salem, NY) male phantom with a dosemeter. Four protocols were tested: round collimation and rectangular collimation, both with and without thyroid shield. Five exposure positions were deployed: upper incisor (Isup), upper canine (Csup), upper premolar (Psup), upper molar (Msup) and posterior bitewing (BW). Exposures were made with 70 kV and 7 mA and were repeated 10 times. The exposure times were as recommended for the exposure positions for the respective collimator type by the manufacturer for digital imaging. The data were statistically analyzed with a three-way ANOVA test. Significance was set at p Isup, thyroid dose levels were comparable with both collimators at a level indicating primary beam exposure. Thyroid shield reduced this dose with circa 75%. For the Csup position, round collimation also revealed primary beam exposure, and thyroid shield yield was 70%. In Csup with rectangular collimation, the thyroid dose was reduced with a factor 4 compared with round collimation and thyroid shield yielded an additional 42% dose reduction. The thyroid dose levels for the Csup, Psup, Msup and BW exposures were lower with rectangular collimation without thyroid shield than with round collimation with thyroid shield. With rectangular collimation, the thyroid shield in Psup, Msup and BW reduced the dose 10% or less, where dose levels were already low, implying no clinical significance. Conclusions: For the exposures in the upper anterior region, thyroid shield results in an important dose reduction for the thyroid. For the other exposures, thyroid shield augments little to the reduction achieved by rectangular collimation. The use of thyroid shield is to be advised, when performing

  1. Bismuth adjuvant ameliorates adverse effects of high-dose chemotherapy in patients with multiple myeloma and malignant lymphoma undergoing autologous stem cell transplantation

    DEFF Research Database (Denmark)

    Hansen, Per Boye; Penkowa, Milena

    2016-01-01

    PURPOSE: High-dose chemotherapy prior to autologous stem cell transplantation (ASCT) leads to adverse effects including mucositis, neutropenia and bacteremia. To reduce the toxicity, we treated myeloma and lymphoma patients with peroral bismuth as an adjuvant to chemotherapy to convey...... cytoprotection in non-malignant cells. METHODS: This trial was a prospective, randomised, double-blind, placebo-controlled pilot study of hematological inpatients (n = 50) receiving bismuth or placebo tablets, in order to identify any potential superiority of bismuth on toxicity from chemotherapy. RESULTS: We....... Also, lymphoma patients' adverse effects were linked to gender. For the first time, bismuth is demonstrated as a safe strategy against chemotherapy's toxicity without interfering with intentional anti-cancer efficiency. Also, we show how gender significantly influences various adverse effects...

  2. Determination of differential dose rates in a mixed beta and gamma field using shielded Al{sub 2}O{sub 3}:C: results of Monte Carlo modelling

    Energy Technology Data Exchange (ETDEWEB)

    Aznar, M.C. E-mail: marianne.aznar@risoe.dk; Nathan, R.; Murray, A.S.; Boetter-Jensen, L

    2003-10-01

    Mixed beta and gamma heterogeneous radiation fields are found in many circumstances, ranging from retrospective dosimetry to medical therapy treatments. It can be very important to provide a direct measurement of the contribution to dose rate from beta particles and gamma rays separately, especially when heterogeneity is on a scale comparable to the range of beta particles (a few mm). In the retrospective dosimetry of heterogeneous sites, in situ measurement at a point may be the only practical method of measuring the appropriate dose rate. Only if the beta and gamma contributions are measured separately can the appropriate water content and grain attenuation corrections be applied. Such corrections are also essential if the full potential of direct dose rate measurement in reducing the overall uncertainty in a luminescence age to much below 5% is ever to be realised. In this paper we outline the results of our modelling of the most appropriate encapsulation for Al{sub 2}O{sub 3}:C luminescence dosimeters when used to measure the dose rate from natural radiation fields. We consider a configuration where one Al{sub 2}O{sub 3}:C chip of a pair is enclosed in a beta-thin light-tight package (which would allow most of the beta radiation to reach the chip); the other in a beta-thick package (which would absorb most beta radiation, hence leaving the chip to record only gamma radiation). The design of the encapsulation is developed using Monte Carlo simulations, and this approach is also used to investigate the sensitivity of the response to the different beta and gamma contributions from uranium, thorium and potassium sources.

  3. Open Rotor Noise Shielding by Blended-Wing-Body Aircraft

    Science.gov (United States)

    Guo, Yueping; Czech, Michael J.; Thomas, Russell H.

    2015-01-01

    This paper presents an analysis of open rotor noise shielding by Blended Wing Body (BWB) aircraft by using model scale test data acquired in the Boeing Low Speed Aeroacoustic Facility (LSAF) with a legacy F7/A7 rotor model and a simplified BWB platform. The objective of the analysis is the understanding of the shielding features of the BWB and the method of application of the shielding data for noise studies of BWB aircraft with open rotor propulsion. By studying the directivity patterns of individual tones, it is shown that though the tonal energy distribution and the spectral content of the wind tunnel test model, and thus its total noise, may differ from those of more advanced rotor designs, the individual tones follow directivity patterns that characterize far field radiations of modern open rotors, ensuring the validity of the use of this shielding data. Thus, open rotor tonal noise shielding should be categorized into front rotor tones, aft rotor tones and interaction tones, not only because of the different directivities of the three groups of tones, but also due to the differences in their source locations and coherence features, which make the respective shielding characteristics of the three groups of tones distinctly different from each other. To reveal the parametric trends of the BWB shielding effects, results are presented with variations in frequency, far field emission angle, rotor operational condition, engine installation geometry, and local airframe features. These results prepare the way for the development of parametric models for the shielding effects in prediction tools.

  4. Shield-related signal instability in magnetoresistive heads

    Science.gov (United States)

    Nakamoto, K.; Narumi, S.; Kawabe, T.; Kobayashi, T.; Fukui, H.

    1999-04-01

    Magnetoresistive (MR) heads with various upper shield materials were fabricated and their read-write performance was tested to clarify the shield-related effect on the signal instability in MR heads. Comparison of a head with an upper shield layer of higher magnetostriction and one with lower magnetostriction showed that the latter had better stability in the output signal of a repeated read-write test. The output amplitude of a head with an upper shield layer of Co52Ni27Fe21 film, which had a high magnetostriction of about +3×10-6, was varied by applying a low external longitudinal field, which affected just the shield layers. This change in the output corresponded well to the output variation in the repeated read-write test. The spin scanning electron micrograph image of this head revealed a distinct domain wall in the air bearing surface near the MR sensor. These results indicated that instability of the domain structure in a shield layer was one of the causes of the signal instability in MR heads; an unusual bias field from a domain wall of the shield layer, which could be moved easily by a repeated writing operation, caused a variation in the biased state of the MR layer which resulted in the signal variation, and that low magnetostriction was required for a shield material to achieve a stable head.

  5. EFFECTS OF INTERFACES ON GAMMA SHIELDING

    Energy Technology Data Exchange (ETDEWEB)

    Clifford, C.E.

    1963-06-15

    A survey is presented of studies of interface effects in gamma shielding problems. These studies are grouped into three types of approaches, viz.: sources at the interface; radiation backscattered from the interface; and radiation transmitted through the interface. A bibliography of 54 references is included. Limitations on the applicability of the results are discussed. (T.F.H.)

  6. A novel synthesis of perovskite bismuth ferrite nanoparticles

    Directory of Open Access Journals (Sweden)

    Alexandre Z. Simões

    2011-09-01

    Full Text Available Microwave assisted hydrothermal (MAH method was used to synthesize crystalline bismuth ferrite (BiFeO3 nanoparticles (BFO at temperature of 180°C with times ranging from 5 min to 1 h. For comparison, BFO powders were also crystallized by the soft chemistry route in a conventional furnace at a temperature of 850°C for 4 h. X-ray diffraction (XRD results verified the formation of perovskite BFO crystallites while infrared data showed no traces of carbonate. Field emission scanning microcopy (FE/SEM revealed a homogeneous size distribution of nanometric BFO powders. MAH method produced nanoparticles of 96% pure perovskite, with a size of 130 nm. These results are in agreement with Raman scattering values which show that the MAH synthesis route is rapid and cost effective. This method could be used as an alternative to other chemical methods in order to obtain BFO nanoparticles.

  7. Shock-Wave Consolidation of Nanostructured Bismuth Telluride Powders

    Science.gov (United States)

    Beck, Jan; Alvarado, Manuel; Nemir, David; Nowell, Mathew; Murr, Lawrence; Prasad, Narasimha

    2012-06-01

    Nanostructured thermoelectric powders can be produced using a variety of techniques. However, it is very challenging to build a bulk material from these nanopowders without losing the nanostructure. In the present work, nanostructured powders of the bismuth telluride alloy system are obtained in kilogram quantities via a gas atomization process. These powders are characterized using a variety of methods including scanning electron microscopy, transition electron microscopy, and x-ray diffraction analysis. Then the powders are consolidated into a dense bulk material using a shock-wave consolidation technique whereby a nanopowder-containing tube is surrounded by explosives and then detonated. The resulting shock wave causes rapid fusing of the powders without the melt and subsequent grain growth of other techniques. We describe the test setup and consolidation results.

  8. Development and verification of signal processing system of avalanche photo diode for the active shields onboard ASTRO-H

    Science.gov (United States)

    Ohno, M.; Kawano, T.; Edahiro, I.; Shirakawa, H.; Ohashi, N.; Okada, C.; Habata, S.; Katsuta, J.; Tanaka, Y.; Takahashi, H.; Mizuno, T.; Fukazawa, Y.; Murakami, H.; Kobayashi, S.; Miyake, K.; Ono, K.; Kato, Y.; Furuta, Y.; Murota, Y.; Okuda, K.; Wada, Y.; Nakazawa, K.; Mimura, T.; Kataoka, J.; Ichinohe, Y.; Uchida, Y.; Katsuragawa, M.; Yoneda, H.; Sato, G.; Sato, R.; Kawaharada, M.; Harayama, A.; Odaka, H.; Hayashi, K.; Ohta, M.; Watanabe, S.; Kokubun, M.; Takahashi, T.; Takeda, S.; Kinoshita, M.; Yamaoka, K.; Tajima, H.; Yatsu, Y.; Uchiyama, H.; Saito, S.; Yuasa, T.; Makishima, K.

    2016-09-01

    The hard X-ray Imager and Soft Gamma-ray Detector onboard ASTRO-H demonstrate high sensitivity to hard X-ray (5-80 keV) and soft gamma-rays (60-600 keV), respectively. To reduce the background, both instruments are actively shielded by large, thick Bismuth Germanate scintillators. We have developed the signal processing system of the avalanche photodiode in the BGO active shields and have demonstrated its effectiveness after assembly in the flight model of the HXI/SGD sensor and after integration into the satellite. The energy threshold achieved is about 150 keV and anti-coincidence efficiency for cosmic-ray events is almost 100%. Installed in the BGO active shield, the developed signal processing system successfully reduces the room background level of the main detector.

  9. Comparison of catalytic activity of bismuth substituted cobalt ferrite nanoparticles synthesized by combustion and co-precipitation method

    Science.gov (United States)

    Kiran, Venkat Savunthari; Sumathi, Shanmugam

    2017-01-01

    In this study, cobalt ferrite and bismuth substituted cobalt ferrite (CoFe2-xBixO4x=0, 0.1) nanoparticles were synthesized by two different methods viz combustion and co-precipitation. The nanoparticles were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), scanning electron microscopy-energy dispersive X-ray analyzer (SEM-EDX) and vibrating sample magnetometer (VSM). The results of powder XRD pattern showed an increase in lattice parameter and decrease in particle size of cobalt ferrite by the substitution of bismuth. Catalytic activity of cobalt ferrite and bismuth substituted cobalt ferrite nanoparticles synthesized by two different methods were compared for the reduction of 4-nitrophenol to 4-aminophenol using NaBH4 as a reducing agent.

  10. Adsorption of volatile polonium and bismuth species on metals in various gas atmospheres. Pt. I. Adsorption of volatile polonium and bismuth on gold

    Energy Technology Data Exchange (ETDEWEB)

    Maugeri, Emilio Andrea; Neuhausen, Joerg; Dressler, Rugard; Piguet, David; Voegele, Alexander; Schumann, Dorothea [Paul Scherrer Institut (PSI), Villigen (Switzerland). Lab. for Radiochemistry; Eichler, Robert [Paul Scherrer Institut (PSI), Villigen (Switzerland). Lab. for Radiochemistry; Bern Univ. (Switzerland). Dept. for Chemistry and Biochemistry; Rijpstra, Kim [Ghent Univ., Zwijnaarde (Belgium). Center for Molecular Modeling (CMM); Cottenier, Stefaan [Ghent Univ., Zwijnaarde (Belgium). Center for Molecular Modeling (CMM); Ghent Univ., Zwijnaarde (Belgium). Dept. of Materials Science and Engineering

    2016-07-01

    Polonium isotopes are considered the most hazardous radionuclides produced during the operation of accelerator driven systems (ADS) when lead-bismuth eutectic (LBE) is used as the reactor coolant and as the spallation target material. In this work the use of gold surfaces for capturing polonium from the cover gas of the ADS reactor was studied by thermochromatography. The results show that gaseous monoatomic polonium, formed in dry hydrogen, is adsorbed on gold at 1058 K. Its adsorption enthalpy was calculated as -250±7 kJ mol{sup -1}, using a Monte Carlo simulation code. Highly volatile polonium species that were observed in similar experiments in fused silica columns in the presence of moisture in both inert and reducing gas were not detected in the experiments studying adsorption on gold surfaces. PoO{sub 2} is formed in both dry and moist oxygen, and its interaction with gold is characterized by transport reactions. The interaction of bismuth, present in large amounts in the atmosphere of the ADS, with gold was also evaluated. It was found that bismuth has a higher affinity for gold, compared to polonium, in an inert, reducing, and oxidizing atmosphere. This fact must be considered when using gold as a material for filtering polonium in the cover gas of ADS.

  11. Welding shield for coupling heaters

    Science.gov (United States)

    Menotti, James Louis

    2010-03-09

    Systems for coupling end portions of two elongated heater portions and methods of using such systems to treat a subsurface formation are described herein. A system may include a holding system configured to hold end portions of the two elongated heater portions so that the end portions are abutted together or located near each other; a shield for enclosing the end portions, and one or more inert gas inlets configured to provide at least one inert gas to flush the system with inert gas during welding of the end portions. The shield may be configured to inhibit oxidation during welding that joins the end portions together. The shield may include a hinged door that, when closed, is configured to at least partially isolate the interior of the shield from the atmosphere. The hinged door, when open, is configured to allow access to the interior of the shield.

  12. Verification of some building materials as gamma-ray shields.

    Science.gov (United States)

    Mann, Kulwinder Singh; Singla, Jyoti; Kumar, Vipan; Sidhu, G S

    2012-08-01

    The shielding properties for gamma rays of a few low Z materials were investigated. The values of the mass attenuation coefficient, equivalent atomic number, effective atomic number, exposure buildup factor and energy absorption buildup factor were calculated and used to estimate the shielding effectiveness of the samples under investigation. It has been observed that the shielding effectiveness of a sample is directly related to its effective atomic number. The shielding character of any sample is a function of the incident photon energy. Good shielding behaviour has been verified in soil samples in the photon energy region of 0.015-0.30 MeV and of dolomite in 3-15 MeV. The results have been shown graphically with more useful conclusions.

  13. Shielding of CO from dissociating radiation in interstellar clouds

    Science.gov (United States)

    Glassgold, A. E.; Huggins, P. J.; Langer, W. D.

    1985-01-01

    The paper investigates the photodissociation of CO in interstellar clouds in the light of recent laboratory studies which suggest that line rather than continuum processes dominate its dissociation by ultraviolet radiation. Using a simple radiative transfer model, the shielding of representative dissociating bands is estimated, including self-shielding, mutual shielding between different isotopes, and near coincidences with strong lines of H2. Each of these processes materially affects the photodestruction rates of the various isotopic species in the transition regions of molecular clouds. These results are combined with an appropriate gas phase chemical model to determine how the abundances of the CO isotopes vary with depth into the cloud. It is found that self-shielding and mutual shielding cause significant variations in isotopic ratios. In addition, fractionation enhances species containing C-13. The relationship between the column densities of CO and H2 is found to vary for the different isotopes and to be sensitive to local conditions.

  14. Experimental research of the effects of different shields on power frequency electric field mitigation

    Directory of Open Access Journals (Sweden)

    Nahman Jovan

    2012-01-01

    Full Text Available The paper describes experimental research on the effects of different shields on power frequency electric field mitigation. This research was performed in order to determine those materials that may be used for electric field mitigation in cases where the reference level is exceeded. Using measured results, the value of the shielding factor has been calculated for all tested shields and the most efficient shields were determined.

  15. A Review on the Production Methods and Testing of Textiles for Electro Magnetic Interference (EMI) shielding

    OpenAIRE

    2015-01-01

    The need of the present generation to protect themselves from electromagnetic radiation due the various technological developments has paved way to the birth of EMI shielding of textiles. The shielding effectiveness of the developed fabric will vary depending upon the fabric or the coating constituents. The shielding requirements for different applications vary widely which has resulted in the development of wide variety of shielding mechanisms and materials which can be used in t...

  16. Compatibility of structural materials with liquid bismuth, lead, and mercury

    Energy Technology Data Exchange (ETDEWEB)

    Weeks, J.R. [Brookhaven National Lab., Upton, NY (United States)

    1996-06-01

    During the 1950s and 1960s, a substantial program existed at Brookhaven National Laboratory as part of the Liquid Metal Fuel reactor program on the compatibility of bismuth, lead, and their alloys with structural materials. Subsequently, compatibility investigations of mercury with structural materials were performed in support of development of Rankine cycle mercury turbines for nuclear applications. The present talk will review present understanding of the corrosion/mass-transfer reactions of structural materials with these liquid metal coolants. Topics to be discussed include the basic solubility relationships of iron, chromium, nickel, and refractory metals in these liquid metals, the results of inhibition studies, the role of oxygen on the corrosion processes, and specialized topics such as cavitation-corrosion and liquid metal embrittlement. Emphasis will be placed on utilizing the understanding gained in this earlier work on the development of heavy liquid metal targets in spallation neutron sources.

  17. Structural investigation of Zn doped sodium bismuth borate glasses

    Science.gov (United States)

    Bhatia, V.; Kumar, D.; Singh, D.; Singh, S. P.

    2016-05-01

    A series of Bismuth Borate Oxide Glass samples with composition x(ZnO):(15-x)Na2O:15Bi2O3:70B2O3 (variation in x is from 6 to 12 mole %) have been prepared by conventional melt quenching technique. All the chemicals used were of Analytical Grade. In order to verify the amorphous nature of the prepared samples the X-Ray Diffraction (XRD) was done. The physical and structural properties have been explored by using the techniques such as density, molar volume and FTIR in order to understand the effect of alkali and transition metal ions on the structure of these glasses. The results obtained by these techniques are in good agreement to one another and with literature as well. With the increase in the content of ZnO, the increase in density and some variations in structural coordination (ratio of BO3 & BO4 structural units) have been observed.

  18. High ionic conductivity in confined bismuth oxide-based heterostructures

    Science.gov (United States)

    Sanna, Simone; Esposito, Vincenzo; Christensen, Mogens; Pryds, Nini

    2016-12-01

    Bismuth trioxide in the cubic fluorite phase (δ -Bi2O3 ) exhibits the highest oxygen ionic conductivity. In this study, we were able to stabilize the pure δ -Bi2O3 at low temperature with no addition of stabilizer but only by engineering the interface, using highly coherent heterostructures made of alternative layers of δ -Bi2O3 and Yttria Stabilized Zirconia (YSZ), deposited by pulsed laser deposition. The resulting [δ -Bi2O3 /YSZ ] heterostructures are found to be stable over a wide temperature range (500-750 °C) and exhibits stable high ionic conductivity over a long time comparable to the value of the pure δ -Bi2O3 , which is approximately two orders of magnitude higher than the conductivity of YSZ bulk.

  19. High ionic conductivity in confined bismuth oxide-based heterostructures

    Directory of Open Access Journals (Sweden)

    Simone Sanna

    2016-12-01

    Full Text Available Bismuth trioxide in the cubic fluorite phase (δ-Bi2O3 exhibits the highest oxygen ionic conductivity. In this study, we were able to stabilize the pure δ-Bi2O3 at low temperature with no addition of stabilizer but only by engineering the interface, using highly coherent heterostructures made of alternative layers of δ-Bi2O3 and Yttria Stabilized Zirconia (YSZ, deposited by pulsed laser deposition. The resulting [δ-Bi2O3/YSZ] heterostructures are found to be stable over a wide temperature range (500-750 °C and exhibits stable high ionic conductivity over a long time comparable to the value of the pure δ-Bi2O3, which is approximately two orders of magnitude higher than the conductivity of YSZ bulk.

  20. Bismuth coatings deposited by the pulsed dc sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, M. F.; Olaya, J. J.; Alfonso, J. E., E-mail: jealfonsoo@unal.edu.co [Universidad Nacional de Colombia, Departamento de Fisica, Grupo de Ciencia de Materiales y Superficies, Carrera 45 No. 26-85, Edif. Uriel Gutierrez, Bogota D. C. (Colombia)

    2013-08-01

    In this work we present the results obtained from the deposition of nano-structured bismuth coatings through Dc pulsed unbalanced magnetron sputtering. The coatings were grown on two substrates: silicon and AISI steel 316 L. The microstructure of the Bi coatings grown on silicon and the corrosion resistance of the Bi coatings grown on AISI steel were evaluated. The microstructure was evaluated by X-ray diffraction and the corrosion resistance was characterized by means of polarization potentiodynamic and electrochemical impedance spectroscopy. Finally the morphology of the coatings was evaluated through scanning electronic microscopy. The X-ray diffraction analysis indicates that the coatings are polycrystalline; the corrosion resistance tests indicate that the films with better corrosion resistance were deposited at 40 khz. Scanning electron microscopy micrographs show that the coatings are grown as granular form. (Author)

  1. Spacesuit Radiation Shield Design Methods

    Science.gov (United States)

    Wilson, John W.; Anderson, Brooke M.; Cucinotta, Francis A.; Ware, J.; Zeitlin, Cary J.

    2006-01-01

    Meeting radiation protection requirements during EVA is predominantly an operational issue with some potential considerations for temporary shelter. The issue of spacesuit shielding is mainly guided by the potential of accidental exposure when operational and temporary shelter considerations fail to maintain exposures within operational limits. In this case, very high exposure levels are possible which could result in observable health effects and even be life threatening. Under these assumptions, potential spacesuit radiation exposures have been studied using known historical solar particle events to gain insight on the usefulness of modification of spacesuit design in which the control of skin exposure is a critical design issue and reduction of blood forming organ exposure is desirable. Transition to a new spacesuit design including soft upper-torso and reconfigured life support hardware gives an opportunity to optimize the next generation spacesuit for reduced potential health effects during an accidental exposure.

  2. Thermal contact conductance and thermal shield design for superconducting magnet systems

    Energy Technology Data Exchange (ETDEWEB)

    Nilles, M.J.; Lehmann, G.A. [Babcock and Wilcox, Lynchburg, VA (United States)

    1994-12-31

    The aluminum radiation shields in the SSC Quadrupole magnets are conductively cooled from the cryogen flow in the 80 K and 20 K flow circuits. As the shield temperature is very sensitive to the effective heat transfer rate between the shield-piping interface, the method of shield mounting and heat sinking is critical. Cost and reliability concerns also drive the design. Here, the authors discuss critical issues that can have a limiting effect on the shield thermal performance. The spring-type action of the shield clamps it in place and heat transfer across the interface depends on thermal contact conductance. Thermally induced stresses can be relieved by allowing the shield and piping to slide relative to each other. Test results are presented on stainless steel-aluminum thermal contact conductance and its effect on the shield performance is discussed.

  3. Dual-modality, fluorescent, PLGA encapsulated bismuth nanoparticles for molecular and cellular fluorescence imaging and computed tomography

    Science.gov (United States)

    Swy, Eric R.; Schwartz-Duval, Aaron S.; Shuboni, Dorela D.; Latourette, Matthew T.; Mallet, Christiane L.; Parys, Maciej; Cormode, David P.; Shapiro, Erik M.

    2014-10-01

    Reports of molecular and cellular imaging using computed tomography (CT) are rapidly increasing. Many of these reports use gold nanoparticles. Bismuth has similar CT contrast properties to gold while being approximately 1000-fold less expensive. Herein we report the design, fabrication, characterization, and CT and fluorescence imaging properties of a novel, dual modality, fluorescent, polymer encapsulated bismuth nanoparticle construct for computed tomography and fluorescence imaging. We also report on cellular internalization and preliminary in vitro and in vivo toxicity effects of these constructs. 40 nm bismuth(0) nanocrystals were synthesized and encapsulated within 120 nm Poly(dl-lactic-co-glycolic acid) (PLGA) nanoparticles by oil-in-water emulsion methodologies. Coumarin-6 was co-encapsulated to impart fluorescence. High encapsulation efficiency was achieved ~70% bismuth w/w. Particles were shown to internalize within cells following incubation in culture. Bismuth nanocrystals and PLGA encapsulated bismuth nanoparticles exhibited >90% and >70% degradation, respectively, within 24 hours in acidic, lysosomal environment mimicking media and both remained nearly 100% stable in cytosolic/extracellular fluid mimicking media. μCT and clinical CT imaging was performed at multiple X-ray tube voltages to measure concentration dependent attenuation rates as well as to establish the ability to detect the nanoparticles in an ex vivo biological sample. Dual fluorescence and CT imaging is demonstrated as well. In vivo toxicity studies in rats revealed neither clinically apparent side effects nor major alterations in serum chemistry and hematology parameters. Calculations on minimal detection requirements for in vivo targeted imaging using these nanoparticles are presented. Indeed, our results indicate that these nanoparticles may serve as a platform for sensitive and specific targeted molecular CT and fluorescence imaging.Reports of molecular and cellular imaging using

  4. Polonium problem in lead-bismuth flow target

    Energy Technology Data Exchange (ETDEWEB)

    Pankratov, D.V.; Yefimov, E.I.; Bugreev, M.I. [State Scientific Centre of Russian Federation-Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1996-06-01

    Alpha-active polonium nuclides Po198 - Po210 are formed in a lead-bismuth target as results of reactions Bi{sup 209}(n,{gamma})Bi{sup 210} {yields} Po{sup 210}, Bi{sup 209}(p,xn)Po{sup 210} {yields} Po{sup 210 {minus} x} (x = 1-12), Pb{sup 208}({alpha},xn) {yields} Po{sup 210 {minus} x + 2} (x = 2-14). The most important nuclides are Po-210 (T{sub {1/2}}=138.4 day), Po-209 (T{sub {1/2}}=102 years) and Po-208 (T{sub {1/2}}=2.9 years). Polonium activity of the circuit for SINQ - conditions is about 15,000 Ci after 1-year operation. Polonium radiation hazard is connected with its output from the coolant and formation of aerosol and surface alpha-activity after the circuit break-down for repair works or in accidents. One of the important issues of polonium removal system creation is containing and storing polonium removed. Its storage in solidified alkaline is not expedient because of secondary neutron formation as a result of ({alpha},n) - reaction on oxygen and sodium nucleus. The estimations carried out demonstrated that by polonium concentration {approx} 100 Ci/l neutron current on the container surface can reach {approx} 10{sup 4}n/(cm{sup 2}s). Concentration and storage of polonium in solidified lead-bisumth seems the most convenient. The calculations demonstrated that in a 100 l container 50,000 Ci of polonium can be stored (as much as 3 times more than 1-year polonium product in SINQ-conditions) under temperature in the container less than melting point of lead bismuth (the wall temperature is about 100{degrees}C).

  5. Study of iron structure stability in high temperature molten lead-bismuth eutectic with oxygen injection using molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Arkundato, Artoto [Physics Department, Faculty of Mathematical and Natural Sciences, Jember University, Jl. Kalimantan 37 Jember (Indonesia); Su' ud, Zaki [Physics Department, Faculty of Mathematical and Natural Sciences, Bandung Institute of Technology, Jl. Ganesha 10, Bandung (Indonesia); Sudarko [Chemistry Department, Faculty of Mathematical and Natural Sciences, Jember University, Jl. Kalimantan 37 Jember (Indonesia); Shafii, Mohammad Ali [Physics Department, Faculty of Mathematical and Natural Sciences, Andalas University, Padang (Indonesia); Celino, Massimo [ENEA, CR Casaccia, Via Anguillarese 301, Rome (Italy)

    2014-09-30

    Corrosion of structural materials in high temperature molten lead-bismuth eutectic is a major problem for design of PbBi cooled reactor. One technique to inhibit corrosion process is to inject oxygen into coolant. In this paper we study and focus on a way of inhibiting the corrosion of iron using molecular dynamics method. For the simulation results we concluded that effective corrosion inhibition of iron may be achieved by injection 0.0532 wt% to 0.1156 wt% oxygen into liquid lead-bismuth. At this oxygen concentration the structure of iron material will be maintained at about 70% in bcc crystal structure during interaction with liquid metal.

  6. Flexible neutron shielding composite material of EPDM rubber with boron trioxide: Mechanical, thermal investigations and neutron shielding tests

    Science.gov (United States)

    Özdemir, T.; Güngör, A.; Reyhancan, İ. A.

    2017-02-01

    In this study, EPDM and boron trioxide composite was produced and mechanical, thermal and neutron shielding tests were performed. EPDM rubber (Ethylene Propylene Diene Monomer) having a considerably high hydrogen content is an effective neutron shielding material. On the other hand, the materials containing boron components have effective thermal neutron absorption crossection. The composite of EPDM and boron trioxide would be an effective solution for both respects of flexibility and effectiveness for developing a neutron shielding material. Flexible nature of EPDM would be a great asset for the shielding purpose in case of intervention action to a radiation accident. The theoretical calculations and experimental neutron absorption tests have shown that the results were in parallel and an effective neutron shielding has been achieved with the use of the developed composite material.

  7. Determining the background levels of bismuth in tissues of wild game birds: a first step in addressing the environmental consequences of using bismuth shotshells.

    Science.gov (United States)

    Jayasinghe, R; Tsuji, L J S; Gough, W A; Karagatzides, J D; Perera, D; Nieboer, E

    2004-11-01

    Bismuth shotshells have been approved as a "nontoxic" alternative to lead in North America. Approval was based on a limited number of studies; even background levels of bismuth in wildfowl were unknown. We report on the concentration of bismuth (and lead) in muscle and liver tissues of wildfowl (Anas platyrhynchos, Anas acuta, Anas crecca, Branta canadensis, Chen caerulescens) harvested with lead shotshell. Average liver-bismuth levels detected in the present study (e.g., teal, 0.05 microg/g dw; mallard, 0.09 microg/g dw) suggest analytical error in other studies examining the effects of bismuth in birds. Significant positive relationships between bismuth- and lead-tissue levels for muscle when all species were combined (and for B. canadensis and C. caerulescens separately) can be explained by noting that bismuth is a contaminant of lead. Thus, more research is recommended to confirm the appropriateness of bismuth as a "nontoxic" shot alternative.

  8. Bismuth-ceramic nanocomposites through ball milling and liquid crystal synthetic methods

    Science.gov (United States)

    Dellinger, Timothy Michael

    Three methods were developed for the synthesis of bismuth-ceramic nanocomposites, which are of interest due to possible use as thermoelectric materials. In the first synthetic method, high energy ball milling of bismuth metal with either MgO or SiO2 was found to produce nanostructured bismuth dispersed on a ceramic material. The morphology of the resulting bismuth depended on its wetting behavior with respect to the ceramic: the metal wet the MgO, but did not wet on the SiO2. Differential Scanning Calorimetry measurements on these composites revealed unusual thermal stability, with nanostructure retained after multiple cycles of heating and cooling through the metal's melting point. The second synthesis methodology was based on the use of lyotropic liquid crystals. These mixtures of water and amphiphilic molecules self-assemble to form periodic structures with nanometer-scale hydrophilic and hydrophobic domains. A novel shear mixing methodology was developed for bringing together reactants which were added to the liquid crystals as dissolved salts. The liquid crystals served to mediate synthesis by acting as nanoreactors to confine chemical reactions within the nanoscale domains of the mesophase, and resulted in the production of nanoparticles. By synthesizing lead sulfide (PbS) and bismuth (Bi) particles as proof-of-concept, it was shown that nanoparticle size could be controlled by controlling the dimensionality of the nanoreactors through control of the liquid crystalline phase. Particle size was shown to decrease upon going from three-dimensionally percolating nanoreactors, to two dimensional sheet-like nanoreactors, to one dimensional rod-like nanoreactors. Additionally, particle size could be controlled by varying the precursor salt concentration. Since the nanoparticles did not agglomerate in the liquid crystal immediately after synthesis, bismuth-ceramic nanocomposites could be prepared by synthesizing Bi nanoparticles and mixing in SiO2 particles which

  9. The Tower Shielding Facility: Its glorious past

    Energy Technology Data Exchange (ETDEWEB)

    Muckenthaler, F.J.

    1997-05-07

    The Tower Shielding Facility (TSF) is the only reactor facility in the US that was designed and built for radiation-shielding studies in which both the reactor source and shield samples could be raised into the air to allow measurements to be made without interference from ground scattering or other spurious effects. The TSF proved its usefulness as many different programs were successfully completed. It became active in work for the Defense Atomic Support Agency (DASA) Space Nuclear Auxiliary Power, Defense Nuclear Agency, Liquid Metal Fast Breeder Reactor Program, the Gas-Cooled and High-Temperature Gas-Cooled Reactor programs, and the Japanese-American Shielding Program of Experimental Research, just to mention a few of the more extensive ones. The history of the TSF as presented in this report describes the various experiments that were performed using the different reactors. The experiments are categorized as to the programs which they supported and placed in corresponding chapters. The experiments are described in modest detail, along with their purpose when appropriate. Discussion of the results is minimal, but references are given to more extensive topical reports.

  10. Radiation Shielding for Manned Deep Space Missions

    Science.gov (United States)

    Adams, James H., Jr.

    2003-01-01

    The arrival of the Expedition 1 Crew at the International Space Station represents the beginning of the continuous presence of man in space. Already we are deploying astronauts and cosmonauts for missions of approx. 6 months onboard the ISS. In the future we can anticipate that more people will be in space and they will be there for longer periods. Even with 6-months deployments to the ISS, the radiation exposure that crew members receive is approaching the exposure limits imposed by the governments of the space- faring nations. In the future we can expect radiation protection to be a dominant consideration for long manned missions. Recognizing this, NASA has expanded their research program on radiation health. This program has three components, bioastronautics, fundamental biology and radiation shielding materials. Bioastronautics is concerned with the investigating the effects of radiation on humans. Fundamental biology investigates the basic mechanisms of radiation damage to tissue. Radiation shielding materials research focuses on developing accurate computational tools to predict the radiation shielding effectiveness of materials. It also investigates new materials that can be used for spacecraft. The radiation shielding materials program will be described and examples of results from the ongoing research will be shown.

  11. Shielding design for a laser-accelerated proton therapy system.

    Science.gov (United States)

    Fan, J; Luo, W; Fourkal, E; Lin, T; Li, J; Veltchev, I; Ma, C-M

    2007-07-07

    In this paper, we present the shielding analysis to determine the necessary neutron and photon shielding for a laser-accelerated proton therapy system. Laser-accelerated protons coming out of a solid high-density target have broad energy and angular spectra leading to dose distributions that cannot be directly used for therapeutic applications. A special particle selection and collimation device is needed to generate desired proton beams for energy- and intensity-modulated proton therapy. A great number of unwanted protons and even more electrons as a side-product of laser acceleration have to be stopped by collimation devices and shielding walls, posing a challenge in radiation shielding. Parameters of primary particles resulting from the laser-target interaction have been investigated by particle-in-cell simulations, which predicted energy spectra with 300 MeV maximum energy for protons and 270 MeV for electrons at a laser intensity of 2 x 10(21) W cm(-2). Monte Carlo simulations using FLUKA have been performed to design the collimators and shielding walls inside the treatment gantry, which consist of stainless steel, tungsten, polyethylene and lead. A composite primary collimator was designed to effectively reduce high-energy neutron production since their highly penetrating nature makes shielding very difficult. The necessary shielding for the treatment gantry was carefully studied to meet the criteria of head leakage shield neutrons and an outer layer of lead was used to reduce photon dose from neutron capture and electron bremsstrahlung. It is shown that the two-layer shielding design with 10-12 cm thick polyethylene and 4 cm thick lead can effectively absorb the unwanted particles to meet the shielding requirements.

  12. Shielding design for a laser-accelerated proton therapy system

    Science.gov (United States)

    Fan, J.; Luo, W.; Fourkal, E.; Lin, T.; Li, J.; Veltchev, I.; Ma, C.-M.

    2007-07-01

    In this paper, we present the shielding analysis to determine the necessary neutron and photon shielding for a laser-accelerated proton therapy system. Laser-accelerated protons coming out of a solid high-density target have broad energy and angular spectra leading to dose distributions that cannot be directly used for therapeutic applications. A special particle selection and collimation device is needed to generate desired proton beams for energy- and intensity-modulated proton therapy. A great number of unwanted protons and even more electrons as a side-product of laser acceleration have to be stopped by collimation devices and shielding walls, posing a challenge in radiation shielding. Parameters of primary particles resulting from the laser-target interaction have been investigated by particle-in-cell simulations, which predicted energy spectra with 300 MeV maximum energy for protons and 270 MeV for electrons at a laser intensity of 2 × 1021 W cm-2. Monte Carlo simulations using FLUKA have been performed to design the collimators and shielding walls inside the treatment gantry, which consist of stainless steel, tungsten, polyethylene and lead. A composite primary collimator was designed to effectively reduce high-energy neutron production since their highly penetrating nature makes shielding very difficult. The necessary shielding for the treatment gantry was carefully studied to meet the criteria of head leakage shield neutrons and an outer layer of lead was used to reduce photon dose from neutron capture and electron bremsstrahlung. It is shown that the two-layer shielding design with 10-12 cm thick polyethylene and 4 cm thick lead can effectively absorb the unwanted particles to meet the shielding requirements.

  13. Thick Galactic Cosmic Radiation Shielding Using Atmospheric Data

    Science.gov (United States)

    Youngquist, Robert C.; Nurge, Mark A.; Starr, Stanley O.; Koontz, Steven L.

    2013-01-01

    NASA is concerned with protecting astronauts from the effects of galactic cosmic radiation and has expended substantial effort in the development of computer models to predict the shielding obtained from various materials. However, these models were only developed for shields up to about 120 g!cm2 in thickness and have predicted that shields of this thickness are insufficient to provide adequate protection for extended deep space flights. Consequently, effort is underway to extend the range of these models to thicker shields and experimental data is required to help confirm the resulting code. In this paper empirically obtained effective dose measurements from aircraft flights in the atmosphere are used to obtain the radiation shielding function of the earth's atmosphere, a very thick shield. Obtaining this result required solving an inverse problem and the method for solving it is presented. The results are shown to be in agreement with current code in the ranges where they overlap. These results are then checked and used to predict the radiation dosage under thick shields such as planetary regolith and the atmosphere of Venus.

  14. Quantitative assessment of selective in-plane shielding of tissues in computed tomography through evaluation of absorbed dose and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Geleijns, J.; Veldkamp, W.J.H. [Leiden University Medical Center, Radiology Department, ZA Leiden (Netherlands); Salvado Artells, M.; Lopez Tortosa, M. [Universitat Rovira i Virgili, Facultat de Medicina i Ciencies de la Salut, Departament de Ciencies Mediques Basiques, Reus, Tarragona (Spain); Calzado Cantera, A. [Universidad Complutense de Madrid, Departamento de Radiologia, Madrid (Spain)

    2006-10-15

    This study aimed at assessment of efficacy of selective in-plane shielding in adults by quantitative evaluation of the achieved dose reduction and image quality. Commercially available accessories for in-plane shielding of the eye lens, thyroid and breast, and an anthropomorphic phantom were used for the evaluation of absorbed dose and image quality. Organ dose and total energy imparted were assessed by means of a Monte Carlo technique taking into account tube voltage, tube current, and scanner type. Image quality was quantified as noise in soft tissue. Application of the lens shield reduced dose to the lens by 27% and to the brain by 1%. The thyroid shield reduced thyroid dose by 26%; the breast shield reduced dose to the breasts by 30% and to the lungs by 15%. Total energy imparted (unshielded/shielded) was 88/86 mJ for computed tomography (CT) brain, 64/60 mJ for CT cervical spine, and 289/260 mJ for CT chest scanning. An increase in image noise could be observed in the ranges were bismuth shielding was applied. The observed reduction of organ dose and total energy imparted could be achieved more efficiently by a reduction of tube current. The application of in-plane selective shielding is therefore discouraged. (orig.)

  15. Pharmacokinetics and bioequivalence of ranitidine and bismuth derived from two compound preparations

    Institute of Scientific and Technical Information of China (English)

    Quan Zhou; Zou-Rong Ruan; Hong Yuan; Bo Jiang; Dong-Hang Xu

    2006-01-01

    AIM: To evaluate the bioequivalence of ranitidine and bismuth derived from two compound preparations.METHODS: The bioavailability was measured in 20healthy male Chinese volunteers following a single oral dose (equivalent to 200 mg of ranitidine and 220 mg of bismuth) of the test or reference products in the fasting state. Then blood samples were collected for 24 h.Plasma concentrations of ranitidine and bismuth were analyzed by high-performance liquid chromatography and inductively coupled plasma-mass spectrometry (ICPMS), respectively. The non-compartmental method was used for pharmacokinetic analysis. Log-transformed Cmax,AUC(0-t) and AUC(0-∞) were tested for bioequivalence using ANOVA and Schuirmann two-one sided t-test. Tmax was analyzed by Wilcoxon's test.RESULTS: Various pharmacokinetic parameters of ranitidine derived from the two compound preparations,including Cmax, AUC(0-t), AUC(0-∞), Tmax and T1/2, were nearly consistent with previous observations. These parameters derived from test and reference drug were as follows: Cmax(0.67 ± 0.21 vs 0.68 ± 0.22mg/L), AUC(0-t)(3.1 ± 0.6 vs 3.0 ± 0.7 mg/L per hour),AUC(0-∞)(3.3 ± 0.6 vs 3.2 ± 0.8 mg/L per hour),Tmax (2.3 ± 0.9 vs 2.1 ± 0.9 h) and T1/2 (2.8 ± 0.3 vs 3.1± 0.4 h). In addition, double-peak absorption profiles of ranitidine were found in some Chinese volunteers.For bismuth, those parameters derived from test and reference drug were as follows: Cmax (11.80 ± 7.36 vs 11.40 ± 6.55 μg/L),AUC(0-t) (46.65 ± 16.97 vs 47.03 ±21.49 μg/L per hour), Tmax (0.50 ± 0.20 vs 0.50 ± 0.20 h)and T1/2 (10.2 ± 2.3 vs 13.0 ± 6.9 h). Ninety percent of confidence intervals for the test/reference ratio of Cmax,AUC(0-t) and AUC(0-∞) derived from both ranitidine and bismuth were found within the bioequivalence acceptable range of 80%-125%. No significant difference was found in Tmax derived from both ranitidine and bismuth.CONCLUSION: The two compound preparations are bioequivalent and may be prescribed

  16. Graphite felt modified with bismuth nanoparticles as negative electrode in a vanadium redox flow battery.

    Science.gov (United States)

    Suárez, David J; González, Zoraida; Blanco, Clara; Granda, Marcos; Menéndez, Rosa; Santamaría, Ricardo

    2014-03-01

    A graphite felt decorated with bismuth nanoparticles was studied as negative electrode in a vanadium redox flow battery (VRFB). The results confirm the excellent electrochemical performance of the bismuth modified electrode in terms of the reversibility of the V(3+) /V(2+) redox reactions and its long-term cycling performance. Moreover a mechanism that explains the role that Bi nanoparticles play in the redox reactions in this negative half-cell is proposed. Bi nanoparticles favor the formation of BiHx , an intermediate that reduces V(3+) to V(2+) and, therefore, inhibits the competitive irreversible reaction of hydrogen formation (responsible for the commonly observed loss of Coulombic efficiency of VRFBs). Thus, the total charge consumed during the cathodic sweep in this electrode is used to reduce V(3+) to V(2+) , resulting in a highly reversible and efficient process.

  17. Shielding synchrotron light sources: Advantages of circular shield walls tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.L. [Design and Accelerator Operations Consulting, 568 Wintergreen Ct Ridge, NY 11961 (United States); Ghosh, V.J.; Breitfeller, M. [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2016-08-11

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produce significantly higher neutron component dose to the experimental floor than lower energy injection and ramped operations. High energy neutrons produced in the forward direction from thin target beam losses are a major component of the dose rate outside the shield walls of the tunnel. The convention has been to provide thicker 90° ratchet walls to reduce this dose to the beam line users. We present an alternate circular shield wall design, which naturally and cost effectively increases the path length for this forward radiation in the shield wall and thereby substantially decreasing the dose rate for these beam losses. This shield wall design will greatly reduce the dose rate to the users working near the front end optical components but will challenge the beam line designers to effectively utilize the longer length of beam line penetration in the shield wall. Additional advantages of the circular shield wall tunnel are that it's simpler to construct, allows greater access to the insertion devices and the upstream in tunnel beam line components, as well as reducing the volume of concrete and therefore the cost of the shield wall.

  18. Shielding synchrotron light sources: Advantages of circular shield walls tunnels

    Science.gov (United States)

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.

    2016-08-01

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produce significantly higher neutron component dose to the experimental floor than lower energy injection and ramped operations. High energy neutrons produced in the forward direction from thin target beam losses are a major component of the dose rate outside the shield walls of the tunnel. The convention has been to provide thicker 90° ratchet walls to reduce this dose to the beam line users. We present an alternate circular shield wall design, which naturally and cost effectively increases the path length for this forward radiation in the shield wall and thereby substantially decreasing the dose rate for these beam losses. This shield wall design will greatly reduce the dose rate to the users working near the front end optical components but will challenge the beam line designers to effectively utilize the longer length of beam line penetration in the shield wall. Additional advantages of the circular shield wall tunnel are that it's simpler to construct, allows greater access to the insertion devices and the upstream in tunnel beam line components, as well as reducing the volume of concrete and therefore the cost of the shield wall.

  19. Monte Carlo based radial shield design of typical PWR reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gul, Anas; Khan, Rustam; Qureshi, M. Ayub; Azeem, Muhammad Waqar; Raza, S.A. [Pakistan Institute of Engineering and Applied Sciences, Islamabad (Pakistan). Dept. of Nuclear Engineering; Stummer, Thomas [Technische Univ. Wien (Austria). Atominst.

    2016-11-15

    Neutron and gamma flux and dose equivalent rate distribution are analysed in radial and shields of a typical PWR type reactor based on the Monte Carlo radiation transport computer code MCNP5. The ENDF/B-VI continuous energy cross-section library has been employed for the criticality and shielding analysis. The computed results are in good agreement with the reference results (maximum difference is less than 56 %). It implies that MCNP5 a good tool for accurate prediction of neutron and gamma flux and dose rates in radial shield around the core of PWR type reactors.

  20. Inhibition of urease by bismuth(III): implications for the mechanism of action of bismuth drugs.

    Science.gov (United States)

    Zhang, Li; Mulrooney, Scott B; Leung, Andy F K; Zeng, Yibo; Ko, Ben B C; Hausinger, Robert P; Sun, Hongzhe

    2006-10-01

    Bismuth compounds are widely used for the treatment of peptic ulcers and Helicobacter pylori infections. It has been suggested that enzyme inhibition plays an important role in the antibacterial activity of bismuth towards this bacterium. Urease, an enzyme that converts urea into ammonia and carbonic acid, is crucial for colonization of the acidic environment of the stomach by H. pylori. Here, we show that three bismuth complexes exhibit distinct mechanisms of urease inhibition, with some differences dependent on the source of the enzyme. Bi(EDTA) and Bi(Cys)(3) are competitive inhibitors of jack bean urease with K(i) values of 1.74 +/- 0.14 and 1.84 +/- 0.15 mM, while the anti-ulcer drug, ranitidine bismuth citrate (RBC) is a non-competitive inhibitor with a K (i) value of 1.17 +/- 0.09 mM. A (13)C NMR study showed that Bi(Cys)(3) reacts with jack bean urease during a 30 min incubation, releasing free cysteines from the metal complex. Upon incubation with Bi(EDTA) and RBC, the number of accessible cysteine residues in the homohexameric plant enzyme decreased by 5.80 +/- 0.17 and 11.94 +/- 0.13, respectively, after 3 h of reaction with dithiobis(2-nitrobenzoic acid). Kinetic analysis showed that Bi(EDTA) is both a competitive inhibitor and a time-dependent inactivator of the recombinant Klebsiella aerogenes urease. The active C319A mutant of the bacterial enzyme displays a significantly reduced sensitivity toward inactivation by Bi(EDTA) compared with the wild-type enzyme, consistent with binding of Bi(3+) to the active site cysteine (Cys(319)) as the mechanism of enzyme inactivation.

  1. Single crystals of bismuth silicon oxide grown by the Czochralski technique and their characterisation

    Directory of Open Access Journals (Sweden)

    ANDREJA VALCIC

    1999-09-01

    Full Text Available Single crystals of Bi12SiO20 were grown by the Czochralski technique. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. X-Ray measurements were performed on powdered samples to obtain the lattice parameters. The optical properties of the bismuth silicon oxide single crystals were investigated. The obtained results are discussed and compared with published data.

  2. Quantum Interference of Surface States in Bismuth Nanowires in Transverse Magnetic Fields

    Science.gov (United States)

    Konopko, L. A.; Huber, T. E.; Nikolaeva, A. A.; Burceacov, L. A.

    2013-06-01

    We report the results of studies of the magnetoresistance (MR) and electric field effect (EFE) of single-crystal Bi nanowires with diameter dMurakami, bismuth bilayers can exhibit the quantum spin Hall effect. A Bi crystal can be viewed as a stacking of bilayers with a honeycomblike lattice structure along the [111] direction. An interpretation of transverse MR oscillations with using this theory is presented.

  3. Multihelix rotating shield brachytherapy for cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Dadkhah, Hossein [Department of Biomedical Engineering, University of Iowa, 1402 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242 (United States); Kim, Yusung; Flynn, Ryan T., E-mail: ryan-flynn@uiowa.edu [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Wu, Xiaodong [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 and Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center for the Engineering Arts and Sciences, Iowa City, Iowa 52242 (United States)

    2015-11-15

    Purpose: To present a novel brachytherapy technique, called multihelix rotating shield brachytherapy (H-RSBT), for the precise angular and linear positioning of a partial shield in a curved applicator. H-RSBT mechanically enables the dose delivery using only linear translational motion of the radiation source/shield combination. The previously proposed approach of serial rotating shield brachytherapy (S-RSBT), in which the partial shield is rotated to several angular positions at each source dwell position [W. Yang et al., “Rotating-shield brachytherapy for cervical cancer,” Phys. Med. Biol. 58, 3931–3941 (2013)], is mechanically challenging to implement in a curved applicator, and H-RSBT is proposed as a feasible solution. Methods: A Henschke-type applicator, designed for an electronic brachytherapy source (Xoft Axxent™) and a 0.5 mm thick tungsten partial shield with 180° or 45° azimuthal emission angles and 116° asymmetric zenith angle, is proposed. The interior wall of the applicator contains six evenly spaced helical keyways that rigidly define the emission direction of the partial radiation shield as a function of depth in the applicator. The shield contains three uniformly distributed protruding keys on its exterior wall and is attached to the source such that it rotates freely, thus longitudinal translational motion of the source is transferred to rotational motion of the shield. S-RSBT and H-RSBT treatment plans with 180° and 45° azimuthal emission angles were generated for five cervical cancer patients with a diverse range of high-risk target volume (HR-CTV) shapes and applicator positions. For each patient, the total number of emission angles was held nearly constant for S-RSBT and H-RSBT by using dwell positions separated by 5 and 1.7 mm, respectively, and emission directions separated by 22.5° and 60°, respectively. Treatment delivery time and tumor coverage (D{sub 90} of HR-CTV) were the two metrics used as the basis for evaluation and

  4. Hierarchical bismuth phosphate microspheres with high photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Lizhai; Wei, Tian; Lin, Nan; Yu, Haiyun [Anhui University of Technology, Ma' anshan (China). Key Laboratory of Materials Science and Processing of Anhui Province

    2016-05-15

    Hierarchical bismuth phosphate microspheres have been prepared by a simple hydrothermal process with polyvinyl pyrrolidone. Scanning electron microscopy observations show that the hierarchical bismuth phosphate microspheres consist of nanosheets with a thickness of about 30 nm. The diameter of the microspheres is about 1 - 3 μm. X-ray diffraction analysis shows that the microspheres are comprised of triclinic Bi{sub 23}P{sub 4}O{sub 44.5} phase. The formation of the hierarchical microspheres depends on polyvinyl pyrrolidone concentration, hydrothermal temperature and reaction time. Gentian violet acts as the pollutant model for investigating the photocatalytic activity of the hierarchical bismuth phosphate microspheres under ultraviolet-visible light irradiation. Irradiation time, dosage of the hierarchical microspheres and initial gentian violet concentration on the photocatalytic efficiency are also discussed. The hierarchical bismuth phosphate microspheres show good photocatalytic performance for gentian violet removal in aqueous solution.

  5. Synthesis and Electrochemical Sensing Toward Heavy Metals of Bunch-like Bismuth Nanostructures

    Directory of Open Access Journals (Sweden)

    Zhang Zhi

    2009-01-01

    Full Text Available Abstract Large-scale bunch-like bismuth (Bi nanostructures were the first time to be synthesized via two-step electrochemical deposition. The growth mechanism of the nanostructures was discussed. Such a designed bunch-like Bi electrode has high sensitivity to detect the heavy metal ions due to its unique three-dimensional structures and strong ability of adsorbing the heavy metal ions. The bunch-like Bi electrode’s detection of heavy metals was statically performed using anodic stripping voltammetry (ASV. The detection in the Pb(II concentration range of 2.5–50 μg/l was also performed. Based on the experimental results, this bunch-like Bi electrode can be considered as an interesting alternative to common mercury electrodes and bismuth film electrodes for possible use in electrochemical studies and electroanalytical applications.

  6. The photorefractive characteristics of bismuth-oxide doped lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Dahuai; Yao, Jiaying [School of Physics, Nankai University, Tianjin 300071 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Kong, Yongfa, E-mail: kongyf@nankai.edu.cn [School of Physics, Nankai University, Tianjin 300071 (China); MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); R and D Center, Taishan Sports Industry Group, Leling 253600 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Liu, Shiguo [School of Physics, Nankai University, Tianjin 300071 (China); Zhang, Ling; Chen, Shaolin [MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); Xu, Jingjun [School of Physics, Nankai University, Tianjin 300071 (China); MOE Key Laboratory of Weak-Light Nonlinear Photonics and TEDA Applied Physics School, Nankai University, Tianjin 300457 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China)

    2015-01-15

    Bismuth-doped lithium niobate (LN:Bi) crystals were grown by Czochralski method and their optical damage resistance, photorefraction, absorption spectra, and defect energy levels were investigated. The experimental results indicate that the photorefractive properties of LN:Bi were enhanced as compared with congruent one, the photorefractive response time was greatly shortened, the photorefractive sensitivity was increased, and the diffraction efficiency of near-stoichiometric LN:Bi (SLN:Bi) reached 31.72% and 49.08% at 532 nm and 488 nm laser, respectively (light intensity of 400 mW/cm{sup 2}). An absorption peak at about 350 nm was observed in the absorption spectrum of LN:Bi. And the defect energy levels simulation indicates new defect levels appear in the forbidden gap of LN:Bi crystals. Therefore bismuth can act as photorefractive centers in LN crystals.

  7. The photorefractive characteristics of bismuth-oxide doped lithium niobate crystals

    Directory of Open Access Journals (Sweden)

    Dahuai Zheng

    2015-01-01

    Full Text Available Bismuth-doped lithium niobate (LN:Bi crystals were grown by Czochralski method and their optical damage resistance, photorefraction, absorption spectra, and defect energy levels were investigated. The experimental results indicate that the photorefractive properties of LN:Bi were enhanced as compared with congruent one, the photorefractive response time was greatly shortened, the photorefractive sensitivity was increased, and the diffraction efficiency of near-stoichiometric LN:Bi (SLN:Bi reached 31.72% and 49.08% at 532 nm and 488 nm laser, respectively (light intensity of 400 mW/cm2. An absorption peak at about 350 nm was observed in the absorption spectrum of LN:Bi. And the defect energy levels simulation indicates new defect levels appear in the forbidden gap of LN:Bi crystals. Therefore bismuth can act as photorefractive centers in LN crystals.

  8. Ab initio lattice dynamics and thermochemistry of layered bismuth telluride (Bi2Te3)

    Science.gov (United States)

    Zurhelle, Alexander F.; Deringer, Volker L.; Stoffel, Ralf P.; Dronskowski, Richard

    2016-03-01

    We present density-functional theory calculations of the lattice dynamics of bismuth telluride, yielding force constants, mean-square displacements and partial densities of phonon states which corroborate and complement previous nuclear inelastic scattering experiments. From these data, we derive an element- and energy-resolved view of the vibrational anharmonicity, quantified by the macroscopic Grüneisen parameter γ which results in 1.56. Finally, we calculate thermochemical properties in the quasiharmonic approximation, especially the heat capacity at constant pressure and the enthalpy of formation for bismuth telluride; the latter arrives at ▵H f (Bi2Te3)  =  -102 kJ mol-1 at 298 K.

  9. On the nature of photoluminescence in Bismuth-doped silica glass.

    Science.gov (United States)

    Laguta, Oleksii V; Hamzaoui, Hicham El; Bouazaoui, Mohamed; Arion, Vladimir B; Razdobreev, Igor M

    2017-06-09

    We report on the investigation of Bismuth-doped pure silica glass without other co-dopant by the tech- nique of magnetic circular dichroism (MCD), which allows the direct probing of the ground state of optical centres. Taking into account the results of conventional optical spectroscopy, we show that the observed MCD bands belong to the centre responsible for the red photoluminescence in this material. Measurements of the temperature and field dependences indicate that the MCD effect is caused by the even-electron system. This, however, opposes the widespread opinion that Bi(2+) ions are the origin of red photoluminescence in Bismuth-doped silica glasses. On the other hand, the lasing centre responsi- ble for the near infrared photoluminescence does not exhibit any magnetic optical activity connected to its ground state. As a consequence, we conclude that the ground state of lasing centre is a magnetic singlet with the effective spin S = 0.

  10. The Role of Bismuth in the Treatment of Gastroduodenal Pathology (Literature Review and Own Researches

    Directory of Open Access Journals (Sweden)

    Yu.M. Stepanov

    2016-10-01

    Full Text Available The article presents the history of colloidal bismuth subcitrate and considers the basic mechanisms of its effects on the gastric mucosa, both cytoprotective and anti-helicobacter. The recent data of the worldwide researches are given on the use of the bismuth subcitrate as a component of antibacterial therapy in order to improve the effectiveness of the eradication, especially under the resistance to the basic drugs. The results of own researches are also shown, they are dedicated to the dynamics of structural adjustment of the gastric mucosa in patients with chronic atrophic gastritis for 3 years after the eradication of H.pylori. The use of first-line therapy with the addition of the drug De-Nol allowed to achieve eradication in 94.3 % of patients and positive microstructural changes of the gastric mucosa.

  11. Bismuth Basic Nitrate as a Novel Adsorbent for Azo Dye Removal

    Directory of Open Access Journals (Sweden)

    E. A. Abdullah

    2012-01-01

    Full Text Available Bismuth basic nitrate (BBN and its TiO2-Ag modified sorbent, PTBA were successfully synthesized via a precipitation method. The structural characteristics of prepared sorbents were determined through different analytical techniques. The potential use of prepared sorbents for organic compounds' removal was evaluated using Methyl Orange and Sunset Yellow dyes as model pollutants in aqueous solutions. The experimental results showed that the presence of TiO2 and Ag particles during the crystal growth of bismuth basic nitrate has an effect on the crystal structure, point of zero charge (pHpzc, pore volume and diameter. The lower binding energy of Ti 2p core level peak indicates the octahedral coordination of TiO2 particles on the PTBA surface. The alteration of hydrophilic-hydrophobic characteristics of sorbent's surface improves the adsorptive performance of the modified sorbent and provides an efficient route for organic contaminants' removal from aqueous solutions.

  12. Mixed-layered bismuth--oxygen--iodine materials for capture and waste disposal of radioactive iodine

    Energy Technology Data Exchange (ETDEWEB)

    Krumhansl, James L; Nenoff, Tina M

    2015-01-06

    Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

  13. Compatibility tests on steels in molten lead and lead-bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Fazio, C. E-mail: concetta@netbra.brasimone.enea.it; Benamati, G.; Martini, C.; Palombarini, G

    2001-07-01

    The compatibility of steels with liquid lead and liquid lead-bismuth is a critical issue for the development of accelerator-driven system (ADS). In this work the results of a set of preliminary tests carried out in stagnant molten lead at 737 K and in lead-bismuth at 573, 673 and 749 K are summarised. The tests were conducted for 700, 1200, 1500 and 5000 h. Three steels were tested: two martensitic steels (mod. F82H and MANET II) and one austenitic steel (AISI 316L). The martensitic steels underwent oxidation phenomena at the higher testing temperature, due to oxygen dissolved in the melts. At a lower test temperature (573 K) and higher exposure time (5000 h) the oxidation rate of the martensitic steel seems to be lower and the developed oxide layer protective against liquid metal corrosion. The austenitic steel, in turn, exhibited an acceptable resistance to corrosion-oxidation under the test conditions.

  14. DARHT : integration of shielding design and analysis with facility design /

    Energy Technology Data Exchange (ETDEWEB)

    Boudrie, R. L. (Richard L.); Brown, T. H. (Thomas H.); Gilmore, W. E. (Walter E.); Downing, J. N. (James N.), Jr.; Hack, Alan; McClure, D. A. (Donald A.); Nelson, C. A. (Christine A.); Wadlinger, E. Alan; Zumbro, M. V. (Martha V.)

    2002-01-01

    The design of the interior portions of the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility incorporated shielding and controls from the beginning of the installation of the Accelerators. The purpose of the design and analysis was to demonstrate the adequacy of shielding or to determine the need for additional shielding or controls. Two classes of events were considered: (1) routine operation defined as the annual production of 10,000 2000-ns pulses of electrons at a nominal energy of 20 MeV, some of which are converted to the x-ray imaging beam consisting of four nominal 60-ns pulses over the 2000-ns time frame, and (2) accident case defined as up to 100 2000-ns pulses of electrons accidentally impinging on some metallic surface, thereby producing x rays. Several locations for both classes of events were considered inside and outside of the accelerator hall buildings. The analysis method consisted of the definition of a source term for each case studied and the definition of a model of the shielding and equipment present between the source and the dose areas. A minimal model of the fixed existing or proposed shielding and equipment structures was used for a first approximation. If the resulting dose from the first approximation was below the design goal (1 rem/yr for routine operations, 5 rem for accident cases), then no further investigations were performed. If the result of the first approximation was above our design goals, the model was refined to include existing or proposed shielding and equipment. In some cases existing shielding and equipment were adequate to meet our goals and in some cases additional shielding was added or administrative controls were imposed to protect the workers. It is expected that the radiation shielding design, exclusion area designations, and access control features, will result in low doses to personnel at the DARHT Facility.

  15. Hybrid Shielding for Magnetic Fields

    Science.gov (United States)

    Mullins, David; Royal, Kevin

    2017-01-01

    Precision symmetry measurements such as the search for the electric dipole moment of the neutron require magnetic shielding rooms to reduce the ambient field to the pT scale. The massive mu-metal sheets and large separation between layers make these shield rooms bulky and expensive. Active field cancellation systems used to reduce the surrounding field are limited in uniformity of cancellation. A novel approach to reducing the space between shield layers and increasing the effectiveness of active cancellation is to combine the two systems into a hybrid system, with active and passive layers interspersed. We demonstrate this idea in a prototype with an active layer sandwiched between two passive layers of shielding.

  16. Radiation shielding for neutron guides

    Science.gov (United States)

    Ersez, T.; Braoudakis, G.; Osborn, J. C.

    2006-11-01

    Models of the neutron guide shielding for the out of bunker guides on the thermal and cold neutron beam lines of the OPAL Reactor (ANSTO) were constructed using the Monte Carlo code MCNP 4B. The neutrons that were not reflected inside the guides but were absorbed by the supermirror (SM) layers were noted to be a significant source of gammas. Gammas also arise from neutrons absorbed by the B, Si, Na and K contained in the glass. The proposed shielding design has produced compact shielding assemblies. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. To verify the design a prototype was assembled consisting of 120 mm thick Pb(96%)Sb(4%) walls resting on a concrete block. There was good agreement between experimental measurements and calculated dose rates for bulk shield regions.

  17. Structural/Radiation-Shielding Epoxies

    Science.gov (United States)

    Connell, John W.; Smith, Joseph G.; Hinkley, Jeffrey; Blattnig, Steve; Delozier, Donavon M.; Watson, Kent A.; Ghose, Sayata

    2009-01-01

    A development effort was directed toward formulating epoxy resins that are useful both as structural materials and as shielding against heavy-ion radiation. Hydrogen is recognized as the best element for absorbing heavy-ion radiation, and high-hydrogen-content polymers are now in use as shielding materials. However, high-hydrogen-content polymers (e.g. polyethylene) are typically not good structural materials. In contrast, aromatic polymers, which contain smaller amounts of hydrogen, often have the strength necessary for structural materials. Accordingly, the present development effort is based on the concept that an ideal structural/ heavy-ion-radiation-shielding material would be a polymer that contains sufficient hydrogen (e.g., in the form of aliphatic molecular groups) for radiation shielding and has sufficient aromatic content for structural integrity.

  18. Some Excitation Functions of Bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, E.L.; Segre, E.

    1948-10-10

    Excitation functions have been measured, using a 38-Mev alpha-beam and a 19-Mev deuteron beam for the following reactions: Bi({alpha},2n)At{sup 211}, Bi({alpha},3n)At{sup 210}, Bi(d,p)Ra E, Bi(d,n)Po{sup 210}, and Bi(d,3n)Po{sup 209}. The results are summarized in Figs. 4 and 5 and Tables I and II. A new isotope of astatine, At{sup 210}, has been identified; this isotope has a half life of 8.3 hr., decaying by K-capture to Po{sup 210} with the emission of a 1.0-Mev gamma-ray and a few conversion electrons.

  19. Fine-tuning the etch depth profile via dynamic shielding of ion beam

    CERN Document Server

    Wu, Lixiang; Fu, Shaojun

    2016-01-01

    We introduce a method for finely adjusting the etch depth profile by dynamic shielding in the course of ion beam etching (IBE), which is crucial for the ultra-precision fabrication of large optics. We study the physical process of dynamic shielding and propose a parametric modeling method to quantitatively analyze the shielding effect on etch depths, or rather the shielding rate, where a piecewise Gaussian model is adopted to fit the shielding rate profile. We have conducted two experiments. In the experiment on parametric modeling of shielding rate profiles, its result shows that the shielding rate profile is significantly influenced by the rotary angle of the leaf. And the experimental result of fine-tuning the etch depth profile shows good agreement with the simulated result, which preliminarily verifies the feasibility of our method.

  20. Diffused phase transition in fine-grained bismuth vanadate ceramics

    OpenAIRE

    Shantha, K; Varma, KBR

    1999-01-01

    Nanocrystalline powders of ferroelectric bismuth vanadate, Bi4V2O11 (n-BiV), with crystallite size less than 50 nm, were obtained by mechanical milling of a stoichiometric mixture of bismuth oxide and vanadium pentoxide. The n-BiV powders on sintering yielded high-density, fine-grained ceramics with improved dielectric and polar characteristics. Dielectric studies on samples obtained from milled powders indicated that the ferroelectric-to-paraelectric phase transition temperature is strongly ...

  1. Thermal neutron shield and method of manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, Bert Clayton; Brindza, Paul Daniel

    2014-03-04

    A thermal neutron shield comprising boron shielding panels with a high percentage of the element Boron. The panel is least 46% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of boron shielding panels which includes enriching the pre-cursor mixture with varying grit sizes of Boron Carbide.

  2. Measuring space radiation shielding effectiveness

    Science.gov (United States)

    Bahadori, Amir; Semones, Edward; Ewert, Michael; Broyan, James; Walker, Steven

    2017-09-01

    Passive radiation shielding is one strategy to mitigate the problem of space radiation exposure. While space vehicles are constructed largely of aluminum, polyethylene has been demonstrated to have superior shielding characteristics for both galactic cosmic rays and solar particle events due to the high hydrogen content. A method to calculate the shielding effectiveness of a material relative to reference material from Bragg peak measurements performed using energetic heavy charged particles is described. Using accelerated alpha particles at the National Aeronautics and Space Administration Space Radiation Laboratory at Brookhaven National Laboratory, the method is applied to sample tiles from the Heat Melt Compactor, which were created by melting material from a simulated astronaut waste stream, consisting of materials such as trash and unconsumed food. The shielding effectiveness calculated from measurements of the Heat Melt Compactor sample tiles is about 10% less than the shielding effectiveness of polyethylene. Shielding material produced from the astronaut waste stream in the form of Heat Melt Compactor tiles is therefore found to be an attractive solution for protection against space radiation.

  3. Shielding requirements in helical tomotherapy

    Science.gov (United States)

    Baechler, S.; Bochud, F. O.; Verellen, D.; Moeckli, R.

    2007-08-01

    Helical tomotherapy is a relatively new intensity-modulated radiation therapy (IMRT) treatment for which room shielding has to be reassessed for the following reasons. The beam-on-time needed to deliver a given target dose is increased and leads to a weekly workload of typically one order of magnitude higher than that for conventional radiation therapy. The special configuration of tomotherapy units does not allow the use of standard shielding calculation methods. A conventional linear accelerator must be shielded for primary, leakage and scatter photon radiations. For tomotherapy, primary radiation is no longer the main shielding issue since a beam stop is mounted on the gantry directly opposite the source. On the other hand, due to the longer irradiation time, the accelerator head leakage becomes a major concern. An analytical model based on geometric considerations has been developed to determine leakage radiation levels throughout the room for continuous gantry rotation. Compared to leakage radiation, scatter radiation is a minor contribution. Since tomotherapy units operate at a nominal energy of 6 MV, neutron production is negligible. This work proposes a synthetic and conservative model for calculating shielding requirements for the Hi-Art II TomoTherapy unit. Finally, the required concrete shielding thickness is given for different positions of interest.

  4. Ultrasonic and Thermal Properties of Borate and Phosphate Glasses Containing Bismuth and Lead

    Science.gov (United States)

    Aziz, Sidek Hj. Abd.; Ahmad, Hamezan; Wahab, Zaidan A.; Sulaiman, Zainal Abidin; Talib, Zainal Abidin; Shaari, A. Halim; Senin, H. B.

    2007-05-01

    Systematic series of (B2O3,P2O5)-Bi2O3-PbO glasses have been successfully prepared by using the rapid quenching technique in which each oxide content changes for every series on the basis of its weight percentage. Their amorphous natures were confirmed earlier by the x-ray diffraction technique. The experimental results show that the density of both glasses, determined by using the Archimedes principle, increases with the glass modifier content. This is due to the replacement of Bi2O3 and PbO in the borate and phosphate glassy networks. The molar volume for borate glass increases with the addition of bismuth and lead oxides, but a reverse trend occurs for the phosphate glass. The longitudinal and shear ultrasound velocities, determined by the MBS 8000 system, of both lead bismuth borate and phosphate glasses show a decreasing trend as more PbO and Bi2O3 are added to the glass system. The increase in PbO/Bi2O3 content was probably related to the progressive increase in the concentration of non-bridging oxygen (NBOs). Thermal studies of the glass, using the Labsys DTA-Setaram machine, show that the value of the glass transition temperature (Tg) is closely related to the chemical bond in the system. In lead bismuth borate glasses, the addition of more Pb2+ and Bi3+ results in a more dominant ionic bond character in the system and hence decreases Tg of the sample. However, in lead bismuth phosphate glasses, the addition of Pb2+ and Bi3+ not only failed to weaken the covalent character in P-O-P bonds, but strengthened it further, leading to an increment in the values of Tg.

  5. Low permeability asphalt concrete gamma ray shielding properties.

    Science.gov (United States)

    Binney, S E; Sykes, K L

    1997-01-01

    Energy-dependent gamma ray shielding properties were measured as a function of gamma ray energy for a low permeability asphalt concrete that is used as a cap to prevent water infiltration into radioactive waste sites. Experimental data were compared to ISO-PC point kernel shielding calculations. Calculated dose equivalent rates compared well with experimental values, especially considering the poor detector resolution involved. The shielding properties of the asphalt concrete closely resembled those of aluminum. The results presented can be used to determine the asphalt concrete thickness required to reduce dose equivalent rates from several gamma ray emitting radionuclides.

  6. Simulation of divertor targets shielding during transients in ITER

    Energy Technology Data Exchange (ETDEWEB)

    Pestchanyi, Sergey, E-mail: serguei.pestchanyi@kit.edu [KIT, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen (Germany); Pitts, Richard; Lehnen, Michael [ITER Organization,Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

    2016-11-01

    Highlights: • We simulated plasma shielding effect during disruption in ITER using the TOKES code. • It has been found that vaporization is unavoidable under action of ITER transients, but plasma shielding drastically reduces the divertor target damage: the melt pool and the vaporization region widths reduced 10–15 times. • A simplified 1D model describing the melt pool depth and the shielded heat flux to the divertor targets have been developed. • The results of the TOKES simulations have been compared with the analytic model when the model is valid. - Abstract: Direct extrapolation of the disruptive heat flux on ITER conditions predicts severe melting and vaporization of the divertor targets causing their intolerable damage. However, tungsten vaporized from the target at initial stage of the disruption can create plasma shield in front of the target, which effectively protects the target surface from the rest of the heat flux. Estimation of this shielding efficiency has been performed using the TOKES code. The shielding effect under ITER conditions is found to be very strong: the maximal depth of the melt layer reduced 4 times, the melt layer width—more than 10 times and vaporization region shrinks 10–15 times due to shielding for unmitigated disruption of 350 MJ discharge. The simulation results show complex, 2D plasma dynamics of the shield under ITER conditions. However, a simplified analytic model, valid for rough estimation of the maximum value for the shielded flux to the target and for the melt depth at the target surface has been developed.

  7. Face shield design against blast-induced head injuries.

    Science.gov (United States)

    Tan, Long Bin; Tse, Kwong Ming; Tan, Yuan Hong; Sapingi, Mohamad Ali Bin; Tan, Vincent Beng Chye; Lee, Heow Pueh

    2017-03-22

    Blast-induced traumatic brain injury has been on the rise in recent years because of the increasing use of improvised explosive devices in conflict zones. Our study investigates the response of a helmeted human head subjected to a blast of 1 atm peak overpressure, for cases with and without a standard polycarbonate (PC) face shield and for face shields comprising of composite PC and aerogel materials and with lateral edge extension. The novel introduction of aerogel into the laminate face shield is explored and its wave-structure interaction mechanics and performance in blast mitigation is analysed. Our numerical results show that the face shield prevented direct exposure of the blast wave to the face and help delays the transmission of the blast to reduce the intracranial pressures (ICPs) at the parietal lobe. However, the blast wave can diffract and enter the midface region at the bottom and side edges of the face shield, resulting in traumatic brain injury. This suggests that the bottom and sides of the face shield are important regions to focus on to reduce wave ingress. The laminated PC/aerogel/PC face shield yielded higher peak positive and negative ICPs at the frontal lobe, than the original PC one. For the occipital and temporal brain regions, the laminated face shield performed better than the original. The composite face shield with extended edges reduced ICP at the temporal lobe but increases ICP significantly at the parietal lobe, which suggests that a greater coverage may not lead to better mitigating effects. Copyright © 2017 John Wiley & Sons, Ltd.

  8. Landau spectrum and twin boundaries of bismuth in the extreme quantum limit.

    Science.gov (United States)

    Zhu, Zengwei; Fauqué, Benoît; Malone, Liam; Antunes, Arlei Borba; Fuseya, Yuki; Behnia, Kamran

    2012-09-11

    The Landau spectrum of bismuth is complex and includes many angle-dependent lines in the extreme quantum limit. The adequacy of single-particle theory to describe this spectrum in detail has been an open issue. Here, we present a study of angle-resolved Nernst effect in bismuth, which maps the angle-resolved Landau spectrum for the entire solid angle up to 28 T. The experimental map is in good agreement with the results of a theoretical model with parabolic dispersion for holes and an extended Dirac Hamiltonian for electrons. The angular dependence of additional lines in the Landau spectrum allows us to uncover the mystery of their origin. They correspond to the lines expected for the hole Landau levels in a secondary crystal tilted by 108°, the angle between twinned crystals in bismuth. According to our results, the electron reservoirs of the two identical tilted crystals have different chemical potentials, and carriers across the twin boundary have different concentrations. An exceptional feature of this junction is that it separates two electron-hole compensated reservoirs. The link between this edge singularity and the states wrapping a three-dimensional electron gas in the quantum limit emerges as an outstanding open question.

  9. Process for making RF shielded cable connector assemblies and the products formed thereby

    Science.gov (United States)

    Fisher, A.; Clatterbuck, C. H. (Inventor)

    1973-01-01

    A process for making RF shielded cable connector assemblies and the resulting structures is described. The process basically consists of potting wires of a shielded cable between the cable shield and a connector housing to fill in, support, regidize, and insulate the individual wires contained in the cable. The formed potting is coated with an electrically conductive material so as to form an entirely encompassing adhering conductive path between the cable shield and the metallic connector housing. A protective jacket is thereby formed over the conductive coating between the cable shield and the connector housing.

  10. In situ electron beam irradiated rapid growth of bismuth nanoparticles in bismuth-based glass dielectrics at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Shiv Prakash; Karmakar, Basudeb, E-mail: basudebk@cgcri.res.in [Central Glass and Ceramic Research Institute (CSIR, India), Glass Science and Technology Section, Glass Division (India)

    2011-09-15

    In this study, in situ control growth of bismuth nanoparticles (Bi{sup 0} NPs) was demonstrated in bismuth-based glass dielectrics under an electron beam (EB) irradiation at room temperature. The effects of EB irradiation were investigated in situ using transmission electron microscopy (TEM), selected-area electron diffraction and high-resolution transmission electron microscopy. The EB irradiation for 2-8 min enhanced the construction of bismuth nanoparticles with a rhombohedral structure and diameter of 4-9 nm. The average particle size was found to increase with the irradiation time. Bismuth metal has a melting point of 271 Degree-Sign C and this low melting temperature makes easy the progress of energy induced structural changes during in situ TEM observations. This is a very useful technique in nano-patterning for integrated optics and other applications.

  11. Studies on bismuth carboxylates—synthesis and characterization of a new structural form of bismuth(III) dipicolinate

    Indian Academy of Sciences (India)

    O Anjaneyulu; K C Kumara Swamy

    2011-03-01

    Synthesis and X-ray structure of a new bismuth dipicolinate cooordination polymer, {[Bi((2,6-O2C)2C5H3N)((2-HO2C-6-O2C)C5H3N)(H2O)]2.5H2O} (7) are presented. Compound 7 has dimeric units with a Bi2O2 skeleton that are linked by additional weak Bi-O interactions leading to a polymeric structure. The overall coordination number at bismuth is 9 [two Bi-N and seven Bi-O bonds]. New routes to a second crystalline modification (4′) of the previously reported coordination polymer, bismuth tris(picolinate), [Bi(2-O2C-C5H4N)3] (4), are described; bond parameters in the two crystalline forms (4 and 4′) are compared. In both the compounds 4′ and 7, bismuth has a distorted tricapped trigonal prismatic geometry.

  12. Effect of bismuth addition to the triple therapy of Helicobacter pylori eradication

    Directory of Open Access Journals (Sweden)

    Ezel Taşdemir

    2012-03-01

    Full Text Available Objective: Success rates of amoxicillin, clarithromycin, and proton-pump inhibitor therapy in the Helicobacter pylori (Hp eradication have been decreasing. The aim of this study was to investigate the impact of bismuth subcitrate addition to triple therapy.Materials and methods: 148 patients diagnosed Hp infection with both histology and Hp stool antigen (HpSA tests were examined retrospectively. The patients were divided into 3 groups according to the eradication therapy. The first group received triple therapy with claritromycine 2x 500 mg, amoxicilline 2x1 g and PPI 2x1 for 14 days (n=40. The second group had bismuth subcitrate 4x120 mg with triple therapy for 14 days (n=73. The third group received 14 days pretreatment with bismuth subcitrate 4x1 together with PPI 2x1 then had triple therapy for 14 days (n=35. (14C urea breath and HpSA tests were used to detect posttreatment H.pylori status.Results: There were no statistical difference between the groups in terms of gender and age (p > 0.05. In group one 12 patients, in group two 20 patients and in group three 10 patients were identified as Hp positive after treatment. Eradication rates were 70% for group one, 72.6% for group two and 71.4% for group three respectively. There was no statistical difference between the groups in terms of eradication rates of treatment (p > 0.05.Conclusions: The addition of bismuth to conventional triple therapy did not affect treatment success rates.

  13. Analysis of the color alteration and radiopacity promoted by bismuth oxide in calcium silicate cement

    Directory of Open Access Journals (Sweden)

    Marina Angelica Marciano

    2013-07-01

    Full Text Available The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO, determined by weight. Mineral trioxide aggregate (MTA was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the ΔE, Δa, Δb and ΔL values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/Tukey tests (p 3 mm equivalent of Al. The MTA group was statistically similar to the CSC / 30% BO group (p > 0.05. In regard to color, the increase of bismuth oxide resulted in a decrease in the ΔE value of the calcium silicate cement. The CSC group presented statistically higher ΔE values than the CSC / 50% BO group (p < 0.05. The comparison between 24 hours and 7 days showed higher ΔE for the MTA group, with statistical differences for the CSC / 15% BO and CSC / 50% BO groups (p < 0.05. After 30 days, CSC showed statistically higher ΔE values than CSC / 30% BO and CSC / 50% BO (p < 0.05. In conclusion, the increase in radiopacity provided by bismuth oxide has no relation to the color alteration of calcium silicate-based cements.

  14. How stable are the 'stable ancient shields'?

    Science.gov (United States)

    Viola, Giulio; Mattila, Jussi

    2014-05-01

    "Archean cratons are relatively flat, stable regions of the crust that have remained undeformed since the Precambrian, forming the ancient cores of the continents" (King, EPSL, 2005). While this type of statement is supported by a wealth of constraints in the case of episodes of thoroughgoing ductile deformation affecting shield regions of Archean and also Peleoproterozoic age, a growing amount of research indicates that shields are not nearly as structurally stable within the broad field of environmental conditions leading to brittle deformation. In fact, old crystalline basements usually present compelling evidence of long brittle deformation histories, often very complex and challenging to unfold. Recent structural and geochronological studies point to a significant mechanical instability of the shield areas, wherein large volumes of 'stable' rocks actually can become saturated with fractures and brittle faults soon after regional cooling exhumes them to below c. 300-350° C. How cold, rigid and therefore strong shields respond to applied stresses remains, however, still poorly investigated and understood. This in turn precludes a better definition of the shallow rheological properties of large, old crystalline blocks. In particular, we do not yet have good constraints on the mechanisms of mechanical reactivation that control the partial (if not total) accommodation of new deformational episodes by preexisting structures, which remains a key to untangle brittle histories lasting several hundred Myr. In our analysis, we use the Svecofennian Shield (SS) as an example of a supposedly 'stable' region with Archean nucleii and Paleoproterozoic cratonic areas to show how it is possible to unravel the details of brittle histories spanning more than 1.5 Gyr. New structural and geochronological results from Finland are integrated with a review of existing data from Sweden to explore how the effects of far-field stresses are partitioned within a shield, which was growing

  15. SHIELD 1.0: development of a shielding calculator program in diagnostic radiology; SHIELD 1.0: desenvolvimento de um programa de calculo de blindagem em radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Romulo R.; Real, Jessica V.; Luz, Renata M. da [Hospital Sao Lucas (PUCRS), Porto Alegre, RS (Brazil); Friedrich, Barbara Q.; Silva, Ana Maria Marques da, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2013-08-15

    In shielding calculation of radiological facilities, several parameters are required, such as occupancy, use factor, number of patients, source-barrier distance, area type (controlled and uncontrolled), radiation (primary or secondary) and material used in the barrier. The shielding design optimization requires a review of several options about the physical facility design and, mainly, the achievement of the best cost-benefit relationship for the shielding material. To facilitate the development of this kind of design, a program to calculate the shielding in diagnostic radiology was implemented, based on data and limits established by National Council on Radiation Protection and Measurements (NCRP) 147 and SVS-MS 453/98. The program was developed in C⌗ language, and presents a graphical interface for user data input and reporting capabilities. The module initially implemented, called SHIELD 1.0, refers to calculating barriers for conventional X-ray rooms. The program validation was performed by the comparison with the results of examples of shielding calculations presented in NCRP 147.

  16. Facile production of thermoelectric bismuth telluride thick films in the presence of polyvinyl alcohol.

    Science.gov (United States)

    Lei, C; Burton, M R; Nandhakumar, I S

    2016-06-01

    Bismuth telluride is currently the best performing thermoelectric material for room temperature operations in commercial thermoelectric devices. We report the reproducible and facile production of 600 micron thick bismuth telluride (Bi2Te3) layers by low cost and room temperature pulsed and potentiostatic electrodeposition from a solution containing bismuth and tellurium dioxide in 2 M nitric acid onto nickel in the presence of polyvinyl alcohol (PVA). This was added to the electrolyte to promote thick layer formation and its effect on the structure, morphology and composition of the electrodeposits was investigated by SEM and EDX. Well adherent, uniform, compact and stoichiometric n-type Bi2Te3 films with a high Seebeck coefficient of up to -200 μV K(-1) and a high electrical conductivity of up to 400 S cm(-1) resulting in a power factor of 1.6 × 10(-3) W m(-1) K(-2) at film growth rates of 100 μm h(-1) for potentiostatic electrodeposition were obtained. The films also exhibited a well defined hexagonal structure as determined by XRD.

  17. Opto-electronic properties of bismuth oxide films presenting different crystallographic phases

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Celia L. [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico); Posgrado en Ciencia e Ingeniería de Materiales, UNAM, Unidad de Posgrado, Edificio C, Piso 1, Zona Cultural de CU, México, D.F. 04510 (Mexico); Depablos-Rivera, Osmary, E-mail: osmarydep@yahoo.com [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico); Posgrado en Ciencia e Ingeniería de Materiales, UNAM, Unidad de Posgrado, Edificio C, Piso 1, Zona Cultural de CU, México, D.F. 04510 (Mexico); Silva-Bermudez, Phaedra [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico); Instituto Nacional de Rehabilitación, Calz. México Xochimilco No. 289 Col. Arenal de Guadalupe, C.P.14389, Ciudad de México, D.F. (Mexico); Muhl, Stephen [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico); Zeinert, Andreas; Lejeune, Michael; Charvet, Stephane; Barroy, Pierre [Laboratoire de Physique de la Matière Condensée, Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex 1 (France); Camps, Enrique [Instituto Nacional de Investigaciones Nucleares, Carretera México-Toluca S/N, kilómetro 36.5. La Marquesa, Municipio de Ocoyoacac, CP 52750, Estado de México (Mexico); Rodil, Sandra E. [Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n CU, México D.F. 04510 (Mexico)

    2015-03-02

    The optical, electrical and structural properties of bismuth oxide thin films deposited by radio frequency reactive magnetron sputtering were studied. The Bi{sub 2}O{sub 3} thin films were grown on Si and glass substrates under different power and substrate temperatures in an oxygen-enriched plasma leading to films with different crystalline phase as evidenced by X-ray diffraction and Raman spectroscopy. The optical properties of the films were measured using ellipsometric spectroscopy and optical transmission spectra. In order to parameterize the optical dispersion functions (n, k) of the films, the Tauc–Lorentz dispersion model was used. The optical bandgap was then assessed by different methods and the results are compared to the thermal variations of the electrical resistivity of the films. It was found that the refractive index, extinction coefficient and optical gap strongly depend on the deposition conditions and the crystalline phase; the fluorite defect cubic δ-Bi{sub 2}O{sub 3} phase showed the lowest optical gap and lower resistivity. - Highlights: • Different bismuth oxide phases were obtained by sputtering. • The power and substrate temperature were the two key parameters. • Room temperature delta-Bi{sub 2}O{sub 3} thin films were obtained. • The optical bandgap was around 1.5 and 2.2 eV, depending on the phase. • The bismuth oxide films presented activation energies around 1 eV.

  18. Bismuth Modified Porous Silica Preparation, Characterization and Photocatalytic Activity Evaluation for Degradation of Isoproturon

    Institute of Scientific and Technical Information of China (English)

    Anil Kumar Reddy Police; Srinivas Basavaraju; Durga Kumari Valluri; Subrahmanyam Machiraju

    2013-01-01

    Porous silica prepared by using an acrylic emulsion has been impregnated with bismuth ion resulting in Bi2Sio5 species containing surface.The as-prepared materials have been characterized by X-ray diffraction spectroscopy (XRD),X-ray photoelectron spectroscopy (XPS),UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS),scanning electron microscopy (SEM),energy dispersive analysis of X-ray (EDAX),transmission electron microscopy (TEM),Fourier transform infrared spectroscopy (FTIR) and N2 adsorption/desorption techniques.EDAX analysis confirms the penetration of bismuth ions into the framework of silica to form Bi2Sio5,which is substantiated by XRD.The UV-Vis DRS shows that the catalysts are optically active and XPS confirms the inclusion of bismuth into the framework of silica.FTIR spectra illustrate the formation of Bi-O-Si linkages in the porous silica framework.SEM and TEM show the spherical morphology,whereas N2 adsorption/desorption study confirms the porosity of the prepared materials.The photocatalytic activity of the material is evaluated for the degradation of isoproturon herbicide and it is found that the material is active as compared to the commercial P-25 Degussa Tio2.

  19. Dirac fermions at high-index surfaces of bismuth chalcogenide topological insulator nanostructures

    Science.gov (United States)

    Virk, Naunidh; Yazyev, Oleg V.

    2016-01-01

    Binary bismuth chalcogenides Bi2Se3, Bi2Te3, and related materials are currently being extensively investigated as the reference topological insulators (TIs) due to their simple surface-state band dispersion (single Dirac cone) and relatively large bulk band gaps. Nanostructures of TIs are of particular interest as an increased surface-to-volume ratio enhances the contribution of surfaces states, meaning they are promising candidates for potential device applications. So far, the vast majority of research efforts have focused on the low-energy (0001) surfaces, which correspond to natural cleavage planes in these layered materials. However, the surfaces of low-dimensional nanostructures (nanoplatelets, nanowires, nanoribbons) inevitably involve higher-index facets. We perform a systematic ab initio investigation of the surfaces of bismuth chalcogenide TI nanostructures characterized by different crystallographic orientations, atomic structures and stoichiometric compositions. We find several stable terminations of high-index surfaces, which can be realized at different values of the chemical potential of one of the constituent elements. For the uniquely defined stoichiometric termination, the topological Dirac fermion states are shown to be strongly anisotropic with a clear dependence of Fermi velocities and spin polarization on the surface orientation. Self-doping effects and the presence of topologically trivial mid-gap states are found to characterize the non-stoichiometric surfaces. The results of our study pave the way towards experimental control of topologically protected surface states in bismuth chalcogenide nanostructures. PMID:26847409

  20. The fabrication and thermal properties of bismuth-aluminum oxide nanothermometers

    Science.gov (United States)

    Wang, Chiu-Yen; Chen, Shih-Hsun; Tsai, Ping-Hsin; Chiou, Chung-Han; Hsieh, Sheng-Jen

    2017-01-01

    Bismuth (Bi) nanowires, well controlled in length and diameter, were prepared by using an anodic aluminum oxide (AAO) template-assisted molding injection process with a high cooling rate. A high performance atomic layer deposition (ALD)-capped bismuth-aluminum oxide (Bi-Al2O3) nanothermometer is demonstrated that was fabricated via a facile, low-cost and low-temperature method, including AAO templated-assisted molding injection and low-temperature ALD-capped processes. The thermal behaviors of Bi nanowires and Bi-Al2O3 nanocables were studied by in situ heating transmission electron microscopy. Linear thermal expansion of liquid Bi within native bismuth oxide nanotubes and ALD-capped Bi-Al2O3 nanocables were evaluated from 275 °C to 700 °C and 300 °C to 1000 °C, respectively. The results showed that the ALD-capped Bi-Al2O3 nanocable possesses the highest working temperature, 1000 °C, and the broadest operation window, 300 °C-1000 °C, of a thermal-expanding type nanothermometer. Our innovative approach provides another way of fabricating core-shell nanocables and to further achieve sensing local temperature under an extreme high vacuum environment.

  1. Simultaneous enhancements in photon absorption and charge transport of bismuth vanadate photoanodes for solar water splitting

    Science.gov (United States)

    Kim, Tae Woo; Ping, Yuan; Galli, Giulia A.; Choi, Kyoung-Shin

    2015-10-01

    n-Type bismuth vanadate has been identified as one of the most promising photoanodes for use in a water-splitting photoelectrochemical cell. The major limitation of BiVO4 is its relatively wide bandgap (~2.5 eV), which fundamentally limits its solar-to-hydrogen conversion efficiency. Here we show that annealing nanoporous bismuth vanadate electrodes at 350 °C under nitrogen flow can result in nitrogen doping and generation of oxygen vacancies. This gentle nitrogen treatment not only effectively reduces the bandgap by ~0.2 eV but also increases the majority carrier density and mobility, enhancing electron-hole separation. The effect of nitrogen incorporation and oxygen vacancies on the electronic band structure and charge transport of bismuth vanadate are systematically elucidated by ab initio calculations. Owing to simultaneous enhancements in photon absorption and charge transport, the applied bias photon-to-current efficiency of nitrogen-treated BiVO4 for solar water splitting exceeds 2%, a record for a single oxide photon absorber, to the best of our knowledge.

  2. The synthesis of bismuth vanadate powders and their photocatalytic properties under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shen Yue [Institute of Material Physical Chemistry, Huaqiao University, Key Laboratory for Functional Materials of Fujian Higher Education, Quanzhou, Fujian 362021 (China); Huang Miaoliang, E-mail: huangml@hqu.edu.c [Institute of Material Physical Chemistry, Huaqiao University, Key Laboratory for Functional Materials of Fujian Higher Education, Quanzhou, Fujian 362021 (China); Huang Yi; Lin Jianming; Wu Jihuai [Institute of Material Physical Chemistry, Huaqiao University, Key Laboratory for Functional Materials of Fujian Higher Education, Quanzhou, Fujian 362021 (China)

    2010-04-30

    Bismuth vanadate powders were prepared by hydrothermal method with NaVO{sub 3} and Bi(NO{sub 3}){sub 3} as starting materials and with Na{sub 2}CO{sub 3} to adjust pH, and characterized by XRD, SEM, EDS and surface area analyzer. The results showed that the phase formation of bismuth vanadate depended on the adding amount of Na{sub 2}CO{sub 3}. The bismuth vanadate samples existed as monoclinic BiVO{sub 4} by adding 0.019 and 0.038 mol of Na{sub 2}CO{sub 3} with corresponding pH value of 0.2 and 5.8, respectively, and as Bi{sub 4}V{sub 2}O{sub 11} by adding 0.057 mol of Na{sub 2}CO{sub 3} with corresponding pH value of 9.7. The photocatalytic activities of the samples were evaluated by the decolorization of methylene blue (MB) under visible light irradiation. The sample with monoclinic form obtained by adding 0.019 mol of Na{sub 2}CO{sub 3} had the highest photocatalytic activity, the decolorization rate of MB reached to 96.4% under visible light irradiation in 200 min and the reaction rate constant was 0.015 min{sup -1}.

  3. Dirac fermions at high-index surfaces of bismuth chalcogenide topological insulator nanostructures

    Science.gov (United States)

    Virk, Naunidh; Yazyev, Oleg V.

    2016-02-01

    Binary bismuth chalcogenides Bi2Se3, Bi2Te3, and related materials are currently being extensively investigated as the reference topological insulators (TIs) due to their simple surface-state band dispersion (single Dirac cone) and relatively large bulk band gaps. Nanostructures of TIs are of particular interest as an increased surface-to-volume ratio enhances the contribution of surfaces states, meaning they are promising candidates for potential device applications. So far, the vast majority of research efforts have focused on the low-energy (0001) surfaces, which correspond to natural cleavage planes in these layered materials. However, the surfaces of low-dimensional nanostructures (nanoplatelets, nanowires, nanoribbons) inevitably involve higher-index facets. We perform a systematic ab initio investigation of the surfaces of bismuth chalcogenide TI nanostructures characterized by different crystallographic orientations, atomic structures and stoichiometric compositions. We find several stable terminations of high-index surfaces, which can be realized at different values of the chemical potential of one of the constituent elements. For the uniquely defined stoichiometric termination, the topological Dirac fermion states are shown to be strongly anisotropic with a clear dependence of Fermi velocities and spin polarization on the surface orientation. Self-doping effects and the presence of topologically trivial mid-gap states are found to characterize the non-stoichiometric surfaces. The results of our study pave the way towards experimental control of topologically protected surface states in bismuth chalcogenide nanostructures.

  4. Underpotential Deposition Study and Determination of Bismuth on Gold Electrode by Using Voltammetry

    Institute of Scientific and Technical Information of China (English)

    DU,Yong-Ling(杜永令); WANG,Chun-Ming(王春明)

    2002-01-01

    The cyclic voltammetry (CV) and the semidifferential anodic stripping voltanmetry (SdASV) were used for investigation of bismuth(Ⅲ) underpotential deposition (UPD) on gold electrode. Based on the excellent electrochemical properties of Au/Bi UPD system, a new method for determining bismuth (Ⅲ)was established. A solution of 0.1 mol/L HNO3 was selected as the supporting electrolyte. Factors affecting the Bi(Ⅲ) UPD and stripping steps were investigated and an opthmized analytical procedure was developed. The calibration plots for Bi(Ⅲ) concentration in the range 1.25 × 10-8-1.0 × 10-7 mol/L were obtained. The detection limit, calculated as three times the standard deviation of the analytical signal of 8.3×10-8 mol/L for a 90 s electrodeposition at 0.00 V (while the solution magnetically stirred at a speed of 300 rpm), was 7.5× 10-9 mol/ L. For8 successive determinations of 1.25 × 10-7 mol/L Bi(Ⅲ), the obtained RSD (relative standard deviation) was 0.4%. The developed method was applied to bismuth determining in medicine and urine samples. The analytical results were compared with that of atomic emission spectrometry (AES) method.

  5. Glass composite waste forms for iodine confined in bismuth-embedded SBA-15

    Science.gov (United States)

    Yang, Jae Hwan; Park, Hwan Seo; Ahn, Do-Hee; Yim, Man-Sung

    2016-11-01

    The aim of this study was to stabilize bismuth-embedded SBA-15 that captured iodine gas by fabrication of monolithic waste forms. The iodine containing waste was mixed with Bi2O3 (a stabilizing additive) and low-temperature sintering glass followed by pelletizing and the sintering process to produce glass composite materials. Iodine volatility during the sintering process was significantly affected by the ratio of Bi2O3 and the glass composition. It was confirmed that BiI3, the main iodine phase within bismuth-embedded SBA-15, was effectively transformed to the mixed phases of Bi5O7I and BiOI. The initial leaching rates of iodine from the glass composite waste forms ranged 10-3-10-2 g/m2 day, showing the stability of the iodine phases encapsulated by the glassy networks. It was also observed that common groundwater anions (e.g., chloride, carbonate, sulfite, and fluoride) elevated the iodine leaching rate by anion exchange reactions. The present results suggest that the glass composite waste form of bismuth-embedded SBA-15 could be a candidate material for stable storage of 129I.

  6. Thermochemically evolved nanoplatelets of bismuth selenide with enhanced thermoelectric figure of merit

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Zulfiqar; Cao, Chuanbao, E-mail: cbcao@bit.edu.cn; Butt, Faheem K.; Tahir, Muhammad; Tanveer, M.; Aslam, Imran; Rizwan, Muhammad; Idrees, Faryal; Khalid, Syed [Research Centre of Materials Science, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Butt, Sajid [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2014-11-15

    We firstly present a simple thermochemical method to fabricate high-quality Bi{sub 2}Se{sub 3} nanoplatelets with enhanced figure of merit using elemental bismuth and selenium powders as precursors. The crystal structure of as synthesized products is characterized via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) measurements. Morphological and chemical synthetic parameters are investigated through a series of experiments; thickness and composition of the platelets are well controlled in large scale production. Subsequently spark plasma sintering (SPS) is performed to fabricate n-type nanostructured bulk thermoelectric materials. Raman Spectroscopy of the two selected samples with approximately of 50 and 100 nm thicknesses shows three vibrational modes. The lower thickness sample exhibits the maximum red shift of about 2.17 cm{sup -1} and maximum broadening of about 10 cm{sup -1} by in-plane vibrational mode E{sup 2}{sub g}. The enhanced value of figure of merit ∼0.41 is obtained for pure phase bismuth selenide to the best of our knowledge. We observe metallic conduction behavior while semiconducting behavior for nanostructured bismuth selenide is reported elsewhere which could be due to different synthetic techniques adopted. These results clearly suggest that our adopted synthetic technique has profound effect on the electronic and thermoelectric transport properties of this material.

  7. A Launch Requirements Trade Study for Active Space Radiation Shielding for Long Duration Human Missions

    Science.gov (United States)

    Singleterry, Robert C., Jr.; Bollweg, Ken; Martin, Trent; Westover, Shayne; Battiston, Roberto; Burger, William J.; Meinke, Rainer

    2015-01-01

    A trade study for an active shielding concept based on magnetic fields in a solenoid configuration versus mass based shielding was developed. Monte Carlo simulations were used to estimate the radiation exposure for two values of the magnetic field strength and the mass of the magnetic shield configuration. For each field strength, results were reported for the magnetic region shielding (end caps ignored) and total region shielding (end caps included but no magnetic field protection) configurations. A value of 15 cSv was chosen to be the maximum exposure for an astronaut. The radiation dose estimate over the total shield region configuration cannot be used at this time without a better understanding of the material and mass present in the end cap regions through a detailed vehicle design. The magnetic shield region configuration, assuming the end cap regions contribute zero exposure, can be launched on a single Space Launch System rocket and up to a two year mission can be supported. The magnetic shield region configuration results in two versus nine launches for a comparable mass based shielding configuration. The active shielding approach is clearly more mass efficient because of the reduced number of launches than the mass based shielding for long duration missions.

  8. Heavy Metal Pad Shielding during Fluoroscopic Interventions

    OpenAIRE

    Dromi, Sergio; Wood, Bradford J.; Oberoi, Jay; Neeman, Ziv

    2006-01-01

    Significant direct and scatter radiation doses to patient and physician may result from routine interventional radiology practice. A lead-free disposable tungsten antimony shielding pad was tested in phantom patients during simulated diagnostic angiography procedures. Although the exact risk of low doses of ionizing radiation is unknown, dramatic dose reductions can be seen with routine use of this simple, sterile pad made from lightweighttungsten antimony material.

  9. Facile synthesis of light harvesting semiconductor bismuth oxychloride nano photo-catalysts for efficient removal of hazardous organic pollutants.

    Science.gov (United States)

    Seddigi, Zaki S; Gondal, Mohammed A; Baig, Umair; Ahmed, Saleh A; Abdulaziz, M A; Danish, Ekram Y; Khaled, Mazen M; Lais, Abul

    2017-01-01

    In the present work, bismuth oxychloride nanoparticles-a light harvesting semiconductor photocatalyst-were synthesized by a facile hydrolysis route, with sodium bismuthate and hydroxylammonium chloride as the precursor materials. The as-synthesized semiconductor photocatalysts were characterized using X-ray diffraction analysis, Fourier transform infra-red spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy, X-ray photoelectron spectroscopy and Photoluminescence spectroscopy techniques. The crystal structure, morphology, composition, and optical properties of these facile synthesized bismuth oxychloride nanoparticles (BiOCl NPs) were compared to those of traditional bismuth oxychloride. In addition, the photocatalytic performance of facile-synthesized BiOCl NPs and traditional BiOCl, as applied to the removal of hazardous organic dyes under visible light illumination, is thoroughly investigated. Our results reveal that facile-synthesized BiOCl NPs display strong UV-Vis light adsorption, improved charge carrier mobility and an inhibited rate of charge carrier recombination, when compared to traditional BiOCl. These enhancements result in an improved photocatalytic degradation rate of hazardous organic dyes under UV-Vis irradiance. For instance, the facile-synthesized BiOCl NPs attained 100% degradation of methylene blue and methyl orange dyes in approximately 30 mins under UV-Vis irradiation, against 55% degradation for traditional BiOCl under similar experimental conditions.

  10. Effect of roxatidine bismuth citrate (MX1) against acetylsalicylic acid- and indomethacin-induced gastric mucosal damage in rats.

    Science.gov (United States)

    Marazova, K; Klouchek, E; Popov, A; Ivanov, C; Krushkov, I; Ichikawa, T; Ishihara, K; Hotta, K

    1998-10-01

    We have studied the effect of the newly synthesized agent, roxatidine bismuth citrate (N-[3-(3-(1-piperidinyl-methyl)phenoxy)propyl]-hydroxyacetamide-2- hydroxypropane-1,2,3-tricarboxylate-bismuth(3+) complex), code name MX1, against acetylsalicylic acid (ASA)- and indomethacin-induced gastric mucosal damage in rats. Effects of MX1 (12.5, 50, 125, 184, 250 mg/kg) were compared to the effects of equimolar doses of roxatidine and bismuth subcitrate. Effect of MX1 (10(-6) M) on mucin biosynthesis measured by [3H] glucosamine incorporation in rat gastric corpus has been determined. MX1-pretreatment dose-dependently decreased the mean ulcer number and length in all doses used in an extent similar to that of roxatidine and more pronounced in comparison with bismuth subcitrate. The morphometrical results have been confirmed histomorphologically. The biosynthesis of mucin was found to be significantly enhanced after MX1 addition. The results of the present study suggest that MX1 has a gastroprotective effect against ASA- and indomethacin-induced ulcers which might be due both to its H2-blocking and mucus-stimulating activity.

  11. Facile synthesis of light harvesting semiconductor bismuth oxychloride nano photo-catalysts for efficient removal of hazardous organic pollutants

    Science.gov (United States)

    Seddigi, Zaki S.; Baig, Umair; Ahmed, Saleh A.; Abdulaziz, M. A.; Danish, Ekram Y.; Khaled, Mazen M.; Lais, Abul

    2017-01-01

    In the present work, bismuth oxychloride nanoparticles–a light harvesting semiconductor photocatalyst–were synthesized by a facile hydrolysis route, with sodium bismuthate and hydroxylammonium chloride as the precursor materials. The as-synthesized semiconductor photocatalysts were characterized using X-ray diffraction analysis, Fourier transform infra-red spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy, X-ray photoelectron spectroscopy and Photoluminescence spectroscopy techniques. The crystal structure, morphology, composition, and optical properties of these facile synthesized bismuth oxychloride nanoparticles (BiOCl NPs) were compared to those of traditional bismuth oxychloride. In addition, the photocatalytic performance of facile-synthesized BiOCl NPs and traditional BiOCl, as applied to the removal of hazardous organic dyes under visible light illumination, is thoroughly investigated. Our results reveal that facile-synthesized BiOCl NPs display strong UV-Vis light adsorption, improved charge carrier mobility and an inhibited rate of charge carrier recombination, when compared to traditional BiOCl. These enhancements result in an improved photocatalytic degradation rate of hazardous organic dyes under UV-Vis irradiance. For instance, the facile-synthesized BiOCl NPs attained 100% degradation of methylene blue and methyl orange dyes in approximately 30 mins under UV-Vis irradiation, against 55% degradation for traditional BiOCl under similar experimental conditions. PMID:28245225

  12. Analysis for Radiation and Shielding Dose in Plasma Focus Neutron Source Using FLUKA

    Science.gov (United States)

    Nemati, M. J.; Amrollahi, R.; Habibi, M.

    2012-06-01

    Monte Carlo simulations have been performed for the attenuation of neutron radiation produced at Plasma focus (PF) devices through various shielding design. At the test site it will be fired with deuterium and tritium (D-T) fusion resulting in a yield of about 1013 fusion neutrons of 14 MeV. This poses a radiological hazard to scientists and personnel operating the device. The goal of this paper was to evaluate various shielding options under consideration for the PF operating with D-T fusion. Shields of varying neutrons-shielding effectiveness were investigated using concrete, polyethylene, paraffin and borated materials. The most effective shield, a labyrinth structure, allowed almost 1,176 shots per year while keeping personnel under 20 mSV of dose. The most expensive shield that used, square shield with 100 cm concrete thickness on the walls and Borated paraffin along with borated polyethylene added outside the concrete allowed almost 15,000 shot per year.

  13. Design and Implementation of Simultaneous Shield And Repeater Insertion for On-chip Interconnects

    Directory of Open Access Journals (Sweden)

    M. Surendra Goud Mr. Y. Sreenivas Goud

    2012-02-01

    Full Text Available A Resource based optimization is a new approach for high performance integrated circuits. The method is applied to simultaneous shield and repeater insertion, resulting in minimum coupling noise under power, delay, and area constraints Repeater insertion is a well known design technique to reduce the delay required to propagate a signal along a line. Shielding inserts an additional line between a victim line and an aggressor line. Finally placing a shield beside and inserting repeaters along a victim line and are chosen to exemplify the resource based optimization process. In the active shielding architecture shield driving circuits as 4:1 multiplexer, full adder, multipliers are inserted. The power consumption of active shielding architecture is observed to be approximately 20% less compare to passive shielding architecture. The main aim of this is minimize the coupling noise under power, delay, and area constraints

  14. Preliminary Analysis of a Water Shield for a Surface Power Reactor

    Science.gov (United States)

    Pearson, J. Boise

    2006-01-01

    A water based shielding system is being investigated for use on initial lunar surface power systems. The use of water may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. A simple 1-D thermal model indicates the necessity of natural convection to maintain acceptable temperatures and pressures in the water shield. CFD analysis is done to quantify the natural convection in the shield, and predicts sufficient natural convection to transfer heat through the shield with small temperature gradients. A test program will he designed to experimentally verify the thermal hydraulic performance of the shield, and to anchor the CFD models to experimental results.

  15. Shielding performance of metal fiber composites

    Institute of Scientific and Technical Information of China (English)

    CHEN Gang; WU Bin; CHEN Ze-fei

    2004-01-01

    Metal fibers have been applied to construct composites with desirable electromagnetic interference shiel ding effectiveness and mechanical properties. Copper and stainless steel fibers were prepared with micro-saw fiberpulling combined cutting method. The cross section of the fibers is hook-like, which is beneficial to the improvement of bonding strength. Cement-based composites with copper and stainless steel fibers were fabricated and their electromagnetic shielding effectiveness was measured in the frequency range of 1 - 5 GHz. The results show that the electromagnetic interference shielding effectiveness of those composites is enhanced by the addition of metal fibers,which functions mainly due to the absorption. At some frequencies, 20 dB or more difference is obtained between the materials with and without metal fibers.

  16. EMC Test Report Electrodynamic Dust Shield

    Science.gov (United States)

    Carmody, Lynne M.; Boyette, Carl B.

    2014-01-01

    This report documents the Electromagnetic Interference E M I evaluation performed on the Electrodynamic Dust Shield (EDS) which is part of the MISSE-X System under the Electrostatics and Surface Physics Laboratory at Kennedy Space Center. Measurements are performed to document the emissions environment associated with the EDS units. The purpose of this report is to collect all information needed to reproduce the testing performed on the Electrodynamic Dust Shield units, document data gathered during testing, and present the results. This document presents information unique to the measurements performed on the Bioculture Express Rack payload; using test methods prepared to meet SSP 30238 requirements. It includes the information necessary to satisfy the needs of the customer per work order number 1037104. The information presented herein should only be used to meet the requirements for which it was prepared.

  17. SHIELD II: WSRT HI Spectral Line Observations

    Science.gov (United States)

    Gordon, Alex Jonah Robert; Cannon, John M.; Adams, Elizabeth A.; SHIELD II Team

    2016-01-01

    The "Survey of HI in Extremely Low-mass Dwarfs II" ("SHIELD II") is a multiwavelength, legacy-class observational campaign that is facilitating the study of both internal and global evolutionary processes in low-mass dwarf galaxies discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We present new results from WSRT HI spectral line observations of 22 galaxies in the SHIELD II sample. We explore the morphology and kinematics by comparing images of the HI surface densities and the intensity weighted velocity fields with optical images from HST, SDSS, and WIYN. In most cases the HI and stellar populations are cospatial; projected rotation velocities range from less than 10 km/s to roughly 30 km/s.Support for this work was provided by NSF grant AST-1211683 to JMC at Macalester College, and by NASA through grant GO-13750 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555.

  18. Electromagnetic and transient shielding effectiveness for near-field sources

    Directory of Open Access Journals (Sweden)

    C. Möller

    2007-06-01

    Full Text Available The contribution deals with an investigation of the recently proposed definitions for the electromagnetic and transient shielding effectiveness (SE in the case of an electric-dipole near-field source. To this end, new factors are introduced which depend on the distance between the dipole source and the measurement point inside the shield and which are valid for perpendicularly (with respect to the distance vector polarized dipoles. Numerical results support and confirm the theoretical derivations.

  19. Effect of bismuth doping on the structural and magnetic properties of zinc-ferrite nanoparticles prepared by a microwave combustion method

    Science.gov (United States)

    Shoushtari, Morteza Zargar; Emami, Akram; Ghahfarokhi, Seyed Ebrahim Mosavi

    2016-12-01

    In this study, we examine the bismuth doping effect on the structural, magnetic and microstructural properties of zinc-ferrite nanoparticles (ZnFe2-xBixO4 with x=0.0, 0.02, 0.04, 0.06, 0.1, 0.15) which have been prepared by a microwave combustion method. The structural, morphological and electromagnetic properties and also Curie temperature of the samples were examined by x-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), vibrating sample magnetometer (VSM), and LCR meter, respectively. In order to measure the energy band gap, the FTIR spectra of the samples were also considered. The XRD patterns of the samples revealed that all of them are ZnFe2O4 structure and no additional peak was observed in their patterns. This implied that the samples were single-phase up to bismuth solubility of 0.15 in Zinc-Ferrite. The results of XRD patterns also showed that the value lattice parameter increases with increasing the bismuth doping. The FESEM results revealed an ascending trend in the size of the nanoparticles. Also considering the VSM results characterized that an increasing the bismuth doping leads to lower the saturation magnetization. The Curie temperatures of the samples were reduced as a result of increasing the amount of bismuth.

  20. Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement

    Directory of Open Access Journals (Sweden)

    Marina Angélica MARCIANO

    2014-07-01

    Full Text Available Objectives: To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. Material and Methods: White Portland cement (WPC was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6. The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p0.05. For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05. The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05. Conclusions: The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.

  1. Sensitive voltammetric determination of lead released from ceramic dishes by using of bismuth nanostructures anchored on biochar.

    Science.gov (United States)

    Agustini, Deonir; Mangrich, Antonio Salvio; Bergamini, Márcio F; Marcolino-Junior, Luiz Humberto

    2015-09-01

    A simple and sensitive electroanalytical method was developed for determination of nanomolar levels of Pb(II) based on the voltammetric stripping response at a carbon paste electrode modified with biochar (a special charcoal) and bismuth nanostructures (nBi-BchCPE). The proposed methodology was based on spontaneous interactions between the highly functionalized biochar surface and Pb(II) ions followed by reduction of these ions into bismuth nanodots which promote an improvement on the stripping anodic current. The experimental procedure could be summarized in three steps: including an open circuit pre-concentration, reduction of accumulated lead ions at the electrode surface and stripping step under differential pulse voltammetric conditions (DPAdSV). SEM images revealed dimensions of bismuth nanodots ranging from 20 nm to 70 nm. The effects of main parameters related to biochar, bismuth and operational parameters were examined in detail. Under the optimal conditions, the proposed sensor has exhibited linear range from 5.0 to 1000 nmol L(-1) and detection limit of 1.41 nmol L(-1) for Pb(II). The optimized method was successfully applied for determination of Pb(II) released from overglaze-decorated ceramic dishes. Results obtained were compared with those given by inductively coupled plasma optical emission spectroscopy (ICP-OES) and they are in agreement at 99% of confidence level. Copyright © 2015. Published by Elsevier B.V.

  2. Radiation Shielding Materials and Containers Incorporating Same

    Energy Technology Data Exchange (ETDEWEB)

    Mirsky, Steven M.; Krill, Stephen J.; and Murray, Alexander P.

    2005-11-01

    An improved radiation shielding material and storage systems for radioactive materials incorporating the same. The PYRolytic Uranium Compound (''PYRUC'') shielding material is preferably formed by heat and/or pressure treatment of a precursor material comprising microspheres of a uranium compound, such as uranium dioxide or uranium carbide, and a suitable binder. The PYRUC shielding material provides improved radiation shielding, thermal characteristic, cost and ease of use in comparison with other shielding materials. The shielding material can be used to form containment systems, container vessels, shielding structures, and containment storage areas, all of which can be used to house radioactive waste. The preferred shielding system is in the form of a container for storage, transportation, and disposal of radioactive waste. In addition, improved methods for preparing uranium dioxide and uranium carbide microspheres for use in the radiation shielding materials are also provided.

  3. Magnetic shielding for superconducting RF cavities

    Science.gov (United States)

    Masuzawa, M.; Terashima, A.; Tsuchiya, K.; Ueki, R.

    2017-03-01

    Magnetic shielding is a key technology for superconducting radio frequency (RF) cavities. There are basically two approaches for shielding: (1) surround the cavity of interest with high permeability material and divert magnetic flux around it (passive shielding); and (2) create a magnetic field using coils that cancels the ambient magnetic field in the area of interest (active shielding). The choice of approach depends on the magnitude of the ambient magnetic field, residual magnetic field tolerance, shape of the magnetic shield, usage, cost, etc. However, passive shielding is more commonly used for superconducting RF cavities. The issue with passive shielding is that as the volume to be shielded increases, the size of the shielding material increases, thereby leading to cost increase. A recent trend is to place a magnetic shield in a cryogenic environment inside a cryostat, very close to the cavities, reducing the size and volume of the magnetic shield. In this case, the shielding effectiveness at cryogenic temperatures becomes important. We measured the permeabilities of various shielding materials at both room temperature and cryogenic temperature (4 K) and studied shielding degradation at that cryogenic temperature.

  4. Thyroid shields and neck exposures in cephalometric radiography

    Directory of Open Access Journals (Sweden)

    Cunha-Cruz Joana

    2006-06-01

    Full Text Available Abstract Background The thyroid is among the more radiosensitive organs in the body. The goal of this study was twofold: (1 to evaluate age-related changes in what is exposed to ionizing radiation in the neck area, and (2 to assess thyroid shield presence in cephalometric radiographs Methods Cephalometric radiographs at one academic setting were sampled and neck exposure was related to calendar year and patient's gender and age. Results In the absence of shields, children have more vertebrae exposed than adults (p Conclusion In the absence of a thyroid shield, children have more neck structure exposed to radiation than adults. In agreement with other reports, thyroid shield utilization in this study was low, particularly in children.

  5. China Plays an Important Role in the World Bismuth Market Place

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>Available statistics shows that China not only has the world largest bismuth deposit but also is the world largest producer, exporter and consumer country. Particularly in the recent three years, China’s production and supply as well as the related policy changes has become a major factor in the bismuth market price fluctuations. China’s bismuth ore production in the recent two years has been kept stable and China’s output of bismuth ore concentrates accounts for

  6. Evaluation of the Prevalence and Utility of Gonad Shielding in Pediatrics Undergoing Pelvic X-Ray

    Directory of Open Access Journals (Sweden)

    Vahid Karami

    2016-11-01

    Full Text Available Background: Gonad shielding has been recommended during pelvic x-rays since the 1950s. The popular method of gonad shielding is placement a lead shield in the midline of the pelvis. The aim of this study was to evaluate the prevalence and utility of gonad shielding in pediatrics undergoing pelvic x-rays.Materials and MethodsFollowing study approval, we retrospectively retrieved data from the digital image library of ten radiology depertments of Khuzestan provience-Iran to identify pediatric patients who underwent pelvic x-ray (anteriorposterior [AP] view. All the images were reviewed for the probable evidence of gonad shield. If there was evidence of shielding, the accuracy positioning of the shield was also investigated by a single assistant radiologist.ResultsIn all 1745 pelvic x-rays (942 girls and 803 boys were identified of which the shield was present in 51 (5.41% radiographs of girls and 132 (16.43% radiographs of boys. When a shield was present; the shields has adequate positioning only in 8 (15.68% radiographs in girls and 59 radiographs in boys. Inaccurate placement and absence of gonad shields were more common in girls than the boys. Due to the shield has concealed the anatomical criteria of the pelvis, retakes of the examination was required in 11 (21.56% radiographs of girls and 14 (10.6% radiographs of boys.ConclusionThe current methods of gonad shielding in girls pelvic x-ray was not effective nor is justifiable. We  no longer advocate of gonad shielding during girls pelvic x-ray. However in boys it is controversial and depends on the skill and effort of radiographers.

  7. Determination of dosimetric parameters for shielded 153Gd source in prostate cancer brachytherapy

    Science.gov (United States)

    Ghorbani, Mahdi; Ghatei, Najmeh; Mehrpouyan, Mohammad; Meigooni, Ali S.; Shahraini, Ramin

    2017-01-01

    Abstract Background Interstitial rotating shield brachytherapy (I-RSBT) is a recently developed method for treatment of prostate cancer. In the present study TG-43 dosimetric parameters of a 153Gd source were obtained for use in I-RSBT. Materials and methods A 153Gd source located inside a needle including a Pt shield and an aluminum window was simulated using MCNPX Monte Carlo code. Dosimetric parameters of this source model, including air kerma strength, dose rate constant, radial dose function and 2D anisotropy function, with and without the shields were calculated according to the TG-43 report. Results The air kerma strength was found to be 6.71 U for the non-shielded source with 1 GBq activity. This value was found to be 0.04 U and 6.19 U for the Pt shield and Al window cases, respectively. Dose rate constant for the non-shielded source was found to be 1.20 cGy/(hU). However, for a shielded source with Pt and aluminum window, dose rate constants were found to be 0.07 cGy/(hU) and 0.96 cGy/(hU), on the shielded and window sides, respectively. The values of radial dose function and anisotropy function were tabulated for these sources. Additionally, isodose curves were drawn for sources with and without shield, in order to evaluate the effect of shield on dose distribution. Conclusions Existence of the Pt shield may greatly reduce the dose to organs at risk and normal tissues which are located toward the shielded side. The calculated air kerma strength, dose rate constant, radial dose function and 2D anisotropy function data for the 153Gd source for the non-shielded and the shielded sources can be used in the treatment planning system (TPS). PMID:28265239

  8. Prognostic Value of Bismuth Typing and Modified T-stage in Hilar Cholangiocarcinoma

    Directory of Open Access Journals (Sweden)

    Shengen Yi

    2015-01-01

    Conclusion: The majority of our patients with HCC were characterized as Subtype IV in Bismuth typing and Stage T3 in modified T-stage. Both Bismuth typing and modified T-stage showed prognostic value in HCC. Compared with Bismuth typing, modified T-stage is a better indicator of the resectability of HCC.

  9. Bismuth X-ray absorber studies for TES microcalorimeters

    Energy Technology Data Exchange (ETDEWEB)

    Sadleir, J.E. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States) and University of Illinois Physics Department, Urbana, IL 61801 (United States)]. E-mail: sadleir@milkyway.gsfc.nasa.gov; Bandler, S.R. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Brekosky, R.P. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Chervenak, J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Figueroa-Feliciano, E. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Finkbeiner, F. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Iyomoto, N. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kelley, R.L. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kilbourne, C.A. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); King, J.M. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Porter, F.S. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Robinson, I.K. [University of Illinois Physics Department, Urbana, IL 61801 (United States); Saab, T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Talley, D.J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2006-04-15

    Bismuth's large atomic number and low carrier density makes it an attractive X-ray absorber material for microcalorimeters. Bismuth's long Fermi wavelength and long mean free paths have motivated much interest in the fabrication of high quality bismuth films to study quantum size effects. Despite such incentives, fabrication of high quality bismuth films has proven difficult, and measured properties of such films are highly variable in the literature. Implementing a bismuth deposition process for TES (superconducting Transition Edge Sensor) device fabrication presents additional challenges particularly at interfaces due to the inherent granularity and surface roughness of its films, its low melting point, and its tendency to diffuse and form undesired intermetallic phases. We report observations of Bi-Cu and Bi-Au diffusion in our devices correlating with large shifts in T{sub c} (superconducting transition temperature). Using SEM and in situ R vs T annealing experiments we have been able to study these diffusion processes and identify their activation temperatures.

  10. Characterization, Leaching, and Filtration Testing for Bismuth Phosphate Sludge (Group 1) and Bismuth Phosphate Saltcake (Group 2) Actual Waste Sample Composites

    Energy Technology Data Exchange (ETDEWEB)

    Lumetta, Gregg J.; Buck, Edgar C.; Daniel, Richard C.; Draper, Kathryn; Edwards, Matthew K.; Fiskum, Sandra K.; Hallen, Richard T.; Jagoda, Lynette K.; Jenson, Evan D.; Kozelisky, Anne E.; MacFarlan, Paul J.; Peterson, Reid A.; Shimskey, Rick W.; Sinkov, Sergey I.; Snow, Lanee A.

    2009-02-19

    A testing program evaluating actual tank waste was developed in response to Task 4 from the M-12 External Flowsheet Review Team (EFRT) issue response plan.() The test program was subdivided into logical increments. The bulk water-insoluble solid wastes that are anticipated to be delivered to the Waste Treatment and Immobilization Plant (WTP) were identified according to type such that the actual waste testing could be targeted to the relevant categories. Eight broad waste groupings were defined. Samples available from the 222S archive were identified and obtained for testing. The actual waste-testing program included homogenizing the samples by group, characterizing the solids and aqueous phases, and performing parametric leaching tests. Two of the eight defined groups—bismuth phosphate sludge (Group 1) and bismuth phosphate saltcake (Group 2)—are the subjects of this report. The Group 1 waste was anticipated to be high in phosphorus and was implicitly assumed to be present as BiPO4 (however, results presented here indicate that the phosphate in Group 1 is actually present as amorphous iron(III) phosphate). The Group 2 waste was also anticipated to be high in phosphorus, but because of the relatively low bismuth content and higher aluminum content, it was anticipated that the Group 2 waste would contain a mixture of gibbsite, sodium phosphate, and aluminum phosphate. Thus, the focus of the Group 1 testing was on determining the behavior of P removal during caustic leaching, and the focus of the Group 2 testing was on the removal of both P and Al. The waste-type definition, archived sample conditions, homogenization activities, characterization (physical, chemical, radioisotope, and crystal habit), and caustic leaching behavior as functions of time, temperature, and hydroxide concentration are discussed in this report. Testing was conducted according to TP-RPP-WTP-467.

  11. Stable high conductivity ceria/bismuth oxide bilayered electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Wachsman, E.D.; Jayaweera, P.; Jiang, N.; Lowe, D.M.; Pound, B.G. [SRI international, Menlo Park, CA (United States). Materials Research Center

    1997-01-01

    The authors have developed a high conductivity bilayered ceria/bismuth oxide anolyte/electrolyte that uses the Po{sub 2} gradient to obtain stability at the anolyte-electrolyte interface and reduced electronic conduction due to the electrolyte region. Results in terms of solid oxide fuel cell (SOFC) performance and stability are presented. These results include a 90 to 160 mV increase in open-circuit potential, depending on temperature, with the bilayered structure as compared to SOFCs fabricated from a single ceria layer. An open-circuit potential of >1.0 V was obtained at 500 C with the bilayered structure. This increase in open-circuit potential is obtained without any measurable increase in cell resistance and is stable for over 1,400 h of testing, under both open-circuit and maximum power conditions. Moreover, SOFCs fabricated from the bilayered structure result in a 33% greater power density as compared to cells with a single ceria electrolyte layer.

  12. High Photon-to-Current Conversion in Solar Cells Based on Light-Absorbing Silver Bismuth Iodide.

    Science.gov (United States)

    Zhu, Huimin; Pan, Mingao; Johansson, Malin B; Johansson, Erik M J

    2017-06-22

    Here, a lead-free silver bismuth iodide (AgI/BiI3 ) with a crystal structure with space group R3‾ m is investigated for use in solar cells. Devices based on the silver bismuth iodide deposited from solution on top of TiO2 and the conducting polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) as a hole-transport layer are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %, which is higher than the performance of previously reported bismuth-halide materials for solar cells. Photocurrent generation is observed between 350 and 700 nm, and the maximum external quantum efficiency is around 45 %. The results are compared to solar cells based on the previously reported material AgBi2 I7 , and we observe a clearly higher performance for the devices with the new silver and bismuth iodides composition and different crystal structure. The X-ray diffraction spectrum of the most efficient silver bismuth iodide material shows a hexagonal crystal structure with space group R3‾ m, and from the light absorption spectrum we obtain an indirect band gap energy of 1.62 eV and a direct band gap energy of 1.85 eV. This report shows the possibility for finding new structures of metal-halides efficient in solar cells and points out new directions for further exploration of lead-free metal-halide solar cells. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  13. High frequency electromagnetic interference shielding magnetic polymer nanocomposites

    Science.gov (United States)

    He, Qingliang

    Electromagnetic interference is one of the most concerned pollution and problem right now since more and more electronic devices have been extensively utilized in our daily lives. Besides the interference, long time exposure to electromagnetic radiation may also result in severe damage to human body. In order to mitigate the undesirable part of the electromagnetic wave energy and maintain the long term sustainable development of our modern civilized society, new technology development based researches have been made to solve this problem. However, one of the major challenges facing to the electromagnetic interference shielding is the relatively low shielding efficiency and the high cost as well as the complicated shielding material manufacture. From the materials science point of view, the key solutions to these challenges are strongly depended on the breakthrough of the current limit of shielding material design and manufacture (such as hierarchical material design with controllable and predictable arrangement in nanoscale particle configuration via an easy in-situ manner). From the chemical engineering point of view, the upgrading of advanced material shielding performance and the enlarged production scale for shielding materials (for example, configure the effective components in the shielding material in order to lower their usage, eliminate the "rate-limiting" step to enlarge the production scale) are of great importance. In this dissertation, the design and preparation of morphology controlled magnetic nanoparticles and their reinforced polypropylene polymer nanocomposites will be covered first. Then, the functionalities of these polymer nanocomposites will be demonstrated. Based on the innovative materials design and synergistic effect on the performance advancement, the magnetic polypropylene polymer nanocomposites with desired multifunctionalities are designed and produced targeting to the electromagnetic interference shielding application. In addition

  14. M-C simulation of shielding effects of PE, LiH and graphite fibers under 1 MeV electrons and 20 MeV protons

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Shielding effects of different materials under 1 MeV electron and 20 MeV proton beams were simulated with Geant4 code. It was found that shielding effects of polyethylene and graphite fibers are much better than aluminum. Energy depositions in the phantom shielded by the materials are calculated, with the least energy deposition by graphite fiber shielding. The results show that graphite fibers are good radiation shielding material in space programs.

  15. LMO dielectronic resonances in highly charged bismuth

    Science.gov (United States)

    Smiga, Joseph; Gillaspy, John; Podpaly, Yuri; Ralchenko, Yuri

    2016-05-01

    Dielectronic resonances from high-Z elements are important for the analysis of high temperature plasmas. Thus, the extreme ultraviolet spectra of highly charged bismuth were measured using the NIST electron beam ion trap (EBIT) at beam energies ranging from 8.7 keV to 9.2 keV. The measured intensity ratios between forbidden magnetic-dipole lines in Bi64+ and Bi63+ show strong resonance features. The experimental data were compared to theoretical predictions from a large-scale collisional-radiative model with the code NOMAD, and good agreement was found that allowed the identification of observed resonance features as the LMO inner-shell dielectronic resonances. It is common practice in EBIT experiments that ions are periodically dumped from the trap and replaced. However, in this particular experiment, the contents of the trap were not dumped for the duration of each 10 minute sampling. The effects of trap stability were studied and a small but noticeable shift in beam energy over time was observed. Potential explanations for this are considered.

  16. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  17. Noise Modeling From Conductive Shields Using Kirchhoff Equations.

    Science.gov (United States)

    Sandin, Henrik J; Volegov, Petr L; Espy, Michelle A; Matlashov, Andrei N; Savukov, Igor M; Schultz, Larry J

    2010-10-01

    Progress in the development of high-sensitivity magnetic-field measurements has stimulated interest in understanding the magnetic noise of conductive materials, especially of magnetic shields based on high-permeability materials and/or high-conductivity materials. For example, SQUIDs and atomic magnetometers have been used in many experiments with mu-metal shields, and additionally SQUID systems frequently have radio frequency shielding based on thin conductive materials. Typical existing approaches to modeling noise only work with simple shield and sensor geometries while common experimental setups today consist of multiple sensor systems with complex shield geometries. With complex sensor arrays used in, for example, MEG and Ultra Low Field MRI studies, knowledge of the noise correlation between sensors is as important as knowledge of the noise itself. This is crucial for incorporating efficient noise cancelation schemes for the system. We developed an approach that allows us to calculate the Johnson noise for arbitrary shaped shields and multiple sensor systems. The approach is efficient enough to be able to run on a single PC system and return results on a minute scale. With a multiple sensor system our approach calculates not only the noise for each sensor but also the noise correlation matrix between sensors. Here we will show how the algorithm can be implemented.

  18. Non-dispersive atomic-fluorescence spectrometry of trace amounts of bismuth by introduction of its gaseous hydride into a premixed argon (entrained air)-hydrogen flame.

    Science.gov (United States)

    Kobayashi, S; Nakahara, T; Musha, S

    1979-10-01

    A method has been developed for the determination of bismuth by generation of its gaseous hydride and introduction of the hydride into a premixed argon (entrained air)-hydrogen flame, the atomic-fluorescence lines from which are all detected by use of a non-dispersive system. The detection limit is 5 pg/ml, or 0.1 ng of bismuth, but the reagent blank found in a 20-ml sample volume was approximately 2 ng of bismuth. Analytical working curves obtained by measuring peak-heights and integrated peak-areas of the signals are linear over a range of about four orders of magnitude from the detection limit. Perchloric, phosphoric and sulphuric acids up to 2.0M concentration give no interference, but nitric acid gives slight depression of the signal. The presence of silver, gold, nickel, palladium, platinum, selenium and tellurium in 1000-fold ratio to bismuth causes pronounced depression of the signal, whereas mercury and tin slightly enhance the atomic-fluorescence signal. The method has been applied to the determination of bismuth in aluminium-base alloys and sulphide ores with use of the standard additions method. The results are in good agreement with those obtained by flame atomic-absorption spectrometry and optical emission spectrometry with an inductively coupled plasma.

  19. Spectrophotometric determination of bismuth in concentrates and non-ferrous alloys by the iodide method after separations by diethyldithiocarbamate and xanthate extraction.

    Science.gov (United States)

    Donaldson, E M

    1978-03-01

    A method for determining 0.0001-1% of bismuth in copper, molybdenum, lead, zinc and nickel sulphide concentrates is described. After sample decomposition, bismuth is separated from matrix and other elements, except lead and thallium(III), by chloroform extraction of its diethyldithiocarbamate complex, pH 11.5-12.0, from a sodium hydroxide medium containing citric acid, tartaric acid, EDTA and potassium cyanide as complexing agents. Following back-extraction of bismuth into 12M hydrochloric acid and reduction of thallium to the univalent state, bismuth is separated from co-extracted lead and thallium by chloroform extraction of its xanthate from a 2.5M hydrochloric acid-tartaric acid-ammonium chloride medium. Bismuth is then determined spectrophotometrically, at 337 or 460 nm, as the iodide. Interference from lead, which is co-extracted in mug-amounts as the xanthate and causes high results at 337 nm, is eliminated by washing the extract with a hydrochloric acid solution of the same composition as the medium used for extraction. The proposed method is also applicable to lead-, tin- and copper-base alloys.

  20. Antibacterial effect of bismuth subsalicylate nanoparticles synthesized by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Castañeda, Mariela [Instituto Nacional de Investigaciones Nucleares (Mexico); Vega-Jiménez, Alejandro L., E-mail: argelia.almaguer@mac.com; Almaguer-Flores, Argelia [Universidad Nacional Autónoma de México, Facultad de Odontología, DEPeI, I (Mexico); Camps, Enrique; Pérez, Mario [Instituto Nacional de Investigaciones Nucleares (Mexico); Silva-Bermudez, Phaedra [Instituto Nacional de Rehabilitación, Unidad de Ingeniería de Tejidos, Terapia Celular y Medicina Regenerativa (Mexico); Berea, Edgardo [FarmaQuimia SA de CV. (Mexico); Rodil, Sandra E. [Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales (Mexico)

    2015-11-15

    The antimicrobial properties of bismuth subsalicylate (BSS) nanoparticles against four opportunistic pathogens; E. coli, P. aeruginosa, S. aureus, and S. epidermidis were determined. BSS nanoparticles were synthesized by pulse laser ablation of a solid target in distilled water under different conditions. The nanoparticles were characterized using high-resolution transmission electron microscopy and absorption spectra and small angle X-ray scattering. The analysis shows that the colloids maintained the BSS structure and presented average particle size between 20 and 60 nm, while the concentration ranges from 95 to 195 mg/L. The antibacterial effect was reported as the inhibition ratio of the bacterial growth after 24 h and the cell viability was measured using the XTT assay. The results showed that the inhibition ratio of E. coli and S. epidermidis was dependant on the NPs size and/or concentration, meanwhile P. aeruginosa and S. aureus were more sensitive to the BSS nanoparticles independently of both the size and the concentration. In general, the BSS colloids with average particle size of 20 nm were the most effective, attaining inhibition ratios >80 %, similar or larger than those obtained with the antibiotic used as control. The results suggest that the BSS colloids could be used as effective antibacterial agents with potential applications in the medical area.

  1. Low eddy current RF shielding enclosure designs for 3T MR applications.

    Science.gov (United States)

    Lee, Brian J; Watkins, Ronald D; Chang, Chen-Ming; Levin, Craig S

    2017-06-06

    Magnetic resonance-compatible medical devices operate within the MR environment while benefitting from the superior anatomic information of MRI. Avoiding electromagnetic interference between such instrumentation and the MR system is crucial. In this work, various shielding configurations for positron emission tomography (PET) detectors were studied and analyzed regarding radiofrequency (RF) shielding effectiveness and gradient-induced eddy current performances. However, the results of this work apply to shielding considerations for any MR-compatible devices. Six shielding enclosure configurations with various thicknesses, patterns, and materials were designed: solid and segmented copper, phosphor bronze mesh (PBM), and carbon fiber composite (CFC). A series of tests was performed on RF shielding effectiveness and the gradient-induced eddy current. For the shielding effectiveness, the solid copper with various thickness and PBM configurations yield significantly better shielding effectiveness (>15 dB) compared with CFC and segmented configurations. For the gradient-induced eddy current performance, the solid copper shielding configurations with different thicknesses showed significantly worse results, up to a factor of 3.89 dB, compared with the segmented copper, PBM, and the CFC configurations. We evaluated the RF shielding effectiveness and the gradient-induced eddy current artifacts of several shielding designs, and only the PBM showed positive outcomes for both aspects. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  2. Decreased dose of radiation to dogs during acquisition of elbow radiographs using draped shielding.

    Science.gov (United States)

    Nemanic, S; Nixon, B K; Francis, R A; Farmer, R H; Harlan, D L; Baltzer, W I

    2015-05-16

    Protective lead equivalent shielding of patients is not routinely used in veterinary radiology. The goal of this study was to determine whether the use of lead equivalent shielding results in a significant reduction in dose of radiation to dogs during acquisition of elbow radiographs. The authors measured radiation doses in the primary beam and over and under protective lead equivalent shielding that was placed at the level of the eyes, body and gonads during acquisition of elbow radiographs using 0.01 mSv sensitivity dosimetry badges. Shielding consisted of 0.5 mm lead equivalent aprons and thyroid shields placed over bodies and eyes, respectively. All badges in the primary beam-detected radiation. Shielding significantly decreased the dose of radiation with significantly less scatter and tube leakage radiation detected under compared with over shielding (P=0.0001). The dose of radiation detected over shielding was significantly greater than zero (P=0.0001), while that under shielding did not differ significantly from zero (P=0.09). Based on these results, the authors recommend protective shielding be used on veterinary patients during radiography.

  3. Bismuth iron oxide thin films using atomic layer deposition of alternating bismuth oxide and iron oxide layers

    Energy Technology Data Exchange (ETDEWEB)

    Puttaswamy, Manjunath; Vehkamäki, Marko [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Kukli, Kaupo, E-mail: kaupo.kukli@helsinki.fi [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); University of Tartu, Institute of Physics, W. Ostwald 1, EE-50411 Tartu (Estonia); Dimri, Mukesh Chandra [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Kemell, Marianna; Hatanpää, Timo; Heikkilä, Mikko J. [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Mizohata, Kenichiro [University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 Helsinki (Finland); Stern, Raivo [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Ritala, Mikko; Leskelä, Markku [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland)

    2016-07-29

    Bismuth iron oxide films with varying contributions from Fe{sub 2}O{sub 3} or Bi{sub 2}O{sub 3} were prepared using atomic layer deposition. Bismuth (III) 2,3-dimethyl-2-butoxide, was used as the bismuth source, iron(III) tert-butoxide as the iron source and water vapor as the oxygen source. The films were deposited as stacks of alternate Bi{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} layers. Films grown at 140 °C to the thickness of 200–220 nm were amorphous, but crystallized upon post-deposition annealing at 500 °C in nitrogen. Annealing of films with intermittent bismuth and iron oxide layers grown to different thicknesses influenced their surface morphology, crystal structure, composition, electrical and magnetic properties. Implications of multiferroic performance were recognized in the films with the remanent charge polarization varying from 1 to 5 μC/cm{sup 2} and magnetic coercivity varying from a few up to 8000 A/m. - Highlights: • Bismuth iron oxide thin films were grown by atomic layer deposition at 140 °C. • The major phase formed in the films upon annealing at 500 °C was BiFeO{sub 3}. • BiFeO{sub 3} films and films containing excess Bi favored electrical charge polarization. • Slight excess of iron oxide enhanced saturative magnetization behavior.

  4. Reliability-Based Electronics Shielding Design Tools

    Science.gov (United States)

    Wilson, J. W.; O'Neill, P. J.; Zang, T. A.; Pandolf, J. E.; Tripathi, R. K.; Koontz, Steven L.; Boeder, P.; Reddell, B.; Pankop, C.

    2007-01-01

    Shielding design on large human-rated systems allows minimization of radiation impact on electronic systems. Shielding design tools require adequate methods for evaluation of design layouts, guiding qualification testing, and adequate follow-up on final design evaluation.

  5. A Novel Radiation Shielding Material Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Radiation shielding simulations showed that epoxy loaded with 10-70% polyethylene would be an excellent shielding material against GCRs and SEPs. Milling produced an...

  6. Material Effectiveness for Radiation Shielding

    Science.gov (United States)

    2003-01-01

    Materials with a smaller mean atomic mass, such as lithium (Li) hydride and polyethylene, make the best radiation shields for astronauts. The materials have a higher density of nuclei and are better able to block incoming radiation. Also, they tend to produce fewer and less dangerous secondary particles after impact with incoming radiation.

  7. Characterization of bismuth nanospheres deposited by plasma focus device

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, M., E-mail: cscientific2@aec.org.sy [IBA Laboratory, Chemistry Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic); Al-Hawat, Sh.; Akel, M. [Physics Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic); Mrad, O. [Chemistry Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic)

    2015-02-14

    A new method for producing thin layer of bismuth nanospheres based on the use of low energy plasma focus device is demonstrated. Various techniques such as scanning electron microscopy, Rutherford backscattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy have been used to characterize the morphology and the composition of the nanospheres. Experimental parameters may be adjusted to favour the formation of bismuth nanospheres instead of microspheres. Therefore, the formation of large surface of homogeneous layer of bismuth nanospheres with sizes of below 100 nm can be obtained. The natural snowball phenomenon is observed to be reproduced in nanoscale where spheres roll over the small nanospheres and grow up to bigger sizes that can reach micro dimensions. The comet-like structure, a reverse phenomenon to snowball is also observed.

  8. Dependence of optical properties of calcium bismuthates on synthesis conditions

    Science.gov (United States)

    Shtarev, D. S.; Shtareva, A. V.

    2016-08-01

    The article studies optical properties of calcium bismuthate nanoparticles of different composition. For the first time the synthesis of these compounds was produced by the pyrolysis of organic precursors using an organic solvent. Characterization of particles was made by scanning electron microscopy and X-ray analysis. The optical properties were investigated by diffuse reflectance spectroscopy (DRS). It is shown that the type of crystal lattice of the particles of calcium bismuthate determines the possibility to control the optical properties of nanoparticles by varying their composition. The conclusions about the production process and the composition of calcium bismuthate, the most promising for use as a photocatalyst of visible light and solar cells, were made.

  9. Predictions for Radiation Shielding Materials

    Science.gov (United States)

    Kiefer, Richard L.

    2002-01-01

    Radiation from galactic cosmic rays (GCR) and solar particle events (SPE) is a serious hazard to humans and electronic instruments during space travel, particularly on prolonged missions outside the Earth s magnetic fields. Galactic cosmic radiation (GCR) is composed of approx. 98% nucleons and approx. 2% electrons and positrons. Although cosmic ray heavy ions are 1-2% of the fluence, these energetic heavy nuclei (HZE) contribute 50% of the long-term dose. These unusually high specific ionizations pose a significant health hazard acting as carcinogens and also causing microelectronics damage inside spacecraft and high-flying aircraft. These HZE ions are of concern for radiation protection and radiation shielding technology, because gross rearrangements and mutations and deletions in DNA are expected. Calculations have shown that HZE particles have a strong preference for interaction with light nuclei. The best shield for this radiation would be liquid hydrogen, which is totally impractical. For this reason, hydrogen-containing polymers make the most effective practical shields. Shielding is required during missions in Earth orbit and possibly for frequent flying at high altitude because of the broad GCR spectrum and during a passage into deep space and LunarMars habitation because of the protracted exposure encountered on a long space mission. An additional hazard comes from solar particle events (SPEs) which are mostly energetic protons that can produce heavy ion secondaries as well as neutrons in materials. These events occur at unpredictable times and can deliver a potentially lethal dose within several hours to an unshielded human. Radiation protection for humans requires safety in short-term missions and maintaining career exposure limits within acceptable levels on future long-term exploration missions. The selection of shield materials can alter the protection of humans by an order of magnitude. If improperly selected, shielding materials can actually

  10. News from the Library: Facilitating access to a program for radiation shielding - the Library can help

    CERN Multimedia

    CERN Library

    2013-01-01

    MicroShield® is a comprehensive photon/gamma ray shielding and dose assessment programme. It is widely used for designing shields, estimating source strength from radiation measurements, minimising exposure to people, and teaching shielding principles.   Integrated tools allow the graphing of results, material and source file creation, source inference with decay (dose-to-Bq calculations accounting for decay and daughter buildup), the projection of exposure rate versus time as a result of decay, access to material and nuclide data, and decay heat calculations. The latest version is able to export results using Microsoft Office (formatted and colour-coded for readability). Sixteen geometries accommodate offset dose points and as many as ten standard shields plus source self-shielding and cylinder cladding are available. The library data (radionuclides, attenuation, build-up and dose conversion) reflect standard data from ICRP 38 and 107* as well as ANSI/ANS standards and RSICC publicat...

  11. Studies on the heat shield structure of ceramic gas turbine components, first report: heat shield properties of the ceramic combustor

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, K.; Hisamatsu, T.; Yuri, I. (CRIEPI, Yokosuka-shi (Japan). Yokosuka Research Lab.)

    1993-04-01

    The ceramic gas turbine for power generation consists of ceramic parts and metal parts. In order to improve the performance and reliability of the ceramic gas turbine, it is important to develop a heat shield structure between ceramics and metal. CRIEPI proposed a heat shield structure for the ceramic combustor wall in which a small amount of air is introduced in a ceramic fibre layer in the ceramic combustor wall. It was confirmed that the heat shield structure has excellent performance in a high pressure combustion test. This report describes the heat transfer property of the heat shield structure in the ceramic combustor wall by numerical analysis. As a result of analysis, it was clarified that the ceramic fibre temperature changes rapidly near the ceramic tiles, and that the heat transfer property of the heat shield structure is as follows: heat shield performance is maintained by introducing a small amount of air; metal wall temperature is little affected by combustion gas temperature, thermophysical property of ceramic fibres and so on. 9 refs., 19 figs., 2 tabs.

  12. Numerical Analysis of Lead-Bismuth-Water Direct Contact Boiling Heat Transfer

    Science.gov (United States)

    Yamada, Yumi; Takahashi, Minoru

    Direct contact boiling heat transfer of sub-cooled water with lead-bismuth eutectic (Pb-Bi) was investigated for the evaluation of the performance of steam generation in direct contact of feed water with primary Pb-Bi coolant in upper plenum above the core in Pb-Bi-cooled direct contact boiling water fast reactor. An analytical two-fluid model was developed to estimate the heat transfer numerically. Numerical results were compared with experimental ones for verification of the model. The overall volumetric heat transfer coefficient was calculated from heat exchange rate in the chimney. It was confirmed that the calculated results agreed well with the experimental result.

  13. Energy levels scheme simulation of divalent cobalt doped bismuth germanate

    Energy Technology Data Exchange (ETDEWEB)

    Andreici, Emiliana-Laura, E-mail: andreicilaura@yahoo.com [Department of Physics, West University of Timisoara, Bd. V. Parvan 4,300223 Timisoara (Romania); Petkova, Petya [Shumen University “Konstantin Preslavsky”, 115 Universitetska street, 9712 Shumen (Bulgaria); Avram, Nicolae M. [Department of Physics, West University of Timisoara, Bd. V. Parvan 4,300223 Timisoara (Romania); Academy of Romanian Scientists, Independentei 54, 050094-Bucharest (Romania)

    2015-12-07

    The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO:Cr{sup 2+} system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of doped BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system.

  14. Thermoelectric characterization of individual bismuth selenide topological insulator nanoribbons

    Science.gov (United States)

    Tang, Hao; Wang, Xiaomeng; Xiong, Yucheng; Zhao, Yang; Zhang, Yin; Zhang, Yan; Yang, Juekuan; Xu, Dongyan

    2015-04-01

    Bismuth selenide (Bi2Se3) nanoribbons have attracted tremendous research interest recently to study the properties of topologically protected surface states that enable new opportunities to enhance the thermoelectric performance. However, the thermoelectric characterization of individual Bi2Se3 nanoribbons is rare due to the technological challenges in the measurements. One challenge is to ensure good contacts between the nanoribbon and electrodes in order to determine the thermal and electrical properties accurately. In this work, we report the thermoelectric characterization of individual Bi2Se3 nanoribbons via a suspended microdevice method. Through careful measurements, we have demonstrated that contact thermal resistance is negligible after the electron-beam-induced deposition (EBID) of platinum/carbon (Pt/C) composites at the contacts between the nanoribbon and electrodes. It is shown that the thermal conductivity of the Bi2Se3 nanoribbons is less than 50% of the bulk value over the whole measurement temperature range, which can be attributed to enhanced phonon boundary scattering. Our results indicate that intrinsic Bi2Se3 nanoribbons prepared in this work are highly doped n-type semiconductors, and therefore the Fermi level should be in the conduction band and no topological transport behavior can be observed in the intrinsic system.

  15. Aromatic amino acids in high selectivity bismuth(III) recognition.

    Science.gov (United States)

    Ghatak, Sumanta Kumar; Dey, Debarati; Sen, Souvik; Sen, Kamalika

    2013-04-21

    The three aromatic amino acids, tyrosine, tryptophan and phenylalanine, play different physiological roles in life processes. Metal ions capable of binding these amino acids may aid in the reduction of effective concentration of these amino acids in any physiological system. Here we have studied the efficacy of some heavy metals for their complexation with these three amino acids. Bismuth has been found to bind selectively with these aromatic amino acids and this was confirmed using spectrofluorimetric, spectrophotometric and cyclic voltammetric studies. The series of heavy metals has been chosen because each of these metals remains associated with the others at very low concentration levels and Bi(III) is the least toxic amongst the other elements. So, selective recognition for Bi(III) would also mean no response for the other heavy elements if contaminants are present even at low concentration levels. The affinity towards these amino acids has been found to be in the order tryptophan phenylalanine amino acids have been calculated using Benesi-Hildebrand equations and the corresponding free energy change has also been calculated. The values of the association constants obtained from BH equations using absorbance values corroborate with the Stern-Volmer constants obtained from fluorimetric studies. The evidence for complexation is also supported by the results of cyclic voltammetry.

  16. WAVS radiation shielding references and assumptions

    Energy Technology Data Exchange (ETDEWEB)

    McLean, Adam [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-07

    At ITER, the confluence of a high radiation environment and the requirement for high performance imaging for plasma and plasma-facing surface diagnosis will necessitate extensive application of radiation shielding. Recommended here is a dual-layer shield design composed of lead for gamma attenuation, surrounded by a fire-resistant polyehtylene doped with a thermal neutron absorber for neutron shielding.

  17. Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, A., E-mail: soumen.basu@phy.nitdgp.ac.in; Banerjee, M., E-mail: soumen.basu@phy.nitdgp.ac.in; Basu, S., E-mail: soumen.basu@phy.nitdgp.ac.in [Department of Physics, National Institute of Technology, Durgapur-713209 (India); Pal, M. [CSIR-Central Mechanical Engineering Research Institute, Durgapur-713209 (India)

    2014-04-24

    Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

  18. Optimal shielding thickness for galactic cosmic ray environments

    Science.gov (United States)

    Slaba, Tony C.; Bahadori, Amir A.; Reddell, Brandon D.; Singleterry, Robert C.; Clowdsley, Martha S.; Blattnig, Steve R.

    2017-02-01

    Models have been extensively used in the past to evaluate and develop material optimization and shield design strategies for astronauts exposed to galactic cosmic rays (GCR) on long duration missions. A persistent conclusion from many of these studies was that passive shielding strategies are inefficient at reducing astronaut exposure levels and the mass required to significantly reduce the exposure is infeasible, given launch and associated cost constraints. An important assumption of this paradigm is that adding shielding mass does not substantially increase astronaut exposure levels. Recent studies with HZETRN have suggested, however, that dose equivalent values actually increase beyond ∼20 g/cm2 of aluminum shielding, primarily as a result of neutron build-up in the shielding geometry. In this work, various Monte Carlo (MC) codes and 3DHZETRN are evaluated in slab geometry to verify the existence of a local minimum in the dose equivalent versus aluminum thickness curve near 20 g/cm2. The same codes are also evaluated in polyethylene shielding, where no local minimum is observed, to provide a comparison between the two materials. Results are presented so that the physical interactions driving build-up in dose equivalent values can be easily observed and explained. Variation of transport model results for light ions (Z ≤ 2) and neutron-induced target fragments, which contribute significantly to dose equivalent for thick shielding, is also highlighted and indicates that significant uncertainties are still present in the models for some particles. The 3DHZETRN code is then further evaluated over a range of related slab geometries to draw closer connection to more realistic scenarios. Future work will examine these related geometries in more detail.

  19. Hydrolysis studies on bismuth nitrate: synthesis and crystallization of four novel polynuclear basic bismuth nitrates.

    Science.gov (United States)

    Miersch, L; Rüffer, T; Schlesinger, M; Lang, H; Mehring, M

    2012-09-03

    Hydrolysis of Bi(NO(3))(3) in aqueous solution gave crystals of the novel compounds [Bi(6)O(4)(OH)(4)(NO(3))(5)(H(2)O)](NO(3)) (1) and [Bi(6)O(4)(OH)(4)(NO(3))(6)(H(2)O)(2)]·H(2)O (2) among the series of hexanuclear bismuth oxido nitrates. Compounds 1 and 2 both crystallize in the monoclinic space group P2(1)/n but show significant differences in their lattice parameters: 1, a = 9.2516(6) Å, b = 13.4298(9) Å, c = 17.8471(14) Å, β = 94.531(6)°, V = 2210.5(3) Å(3); 2, a = 9.0149(3) Å, b = 16.9298(4) Å, c = 15.6864(4) Å, β = 90.129(3)°, V = 2394.06(12) Å(3). Variation of the conditions for partial hydrolysis of Bi(NO(3))(3) gave bismuth oxido nitrates of even higher nuclearity, [{Bi(38)O(45)(NO(3))(24)(DMSO)(26)}·4DMSO][{Bi(38)O(45)(NO(3))(24)(DMSO)(24)}·4DMSO] (3) and [{Bi(38)O(45)(NO(3))(24)(DMSO)(26)}·2DMSO][{Bi(38)O(45)(NO(3))(24)(DMSO)(24)}·0.5DMSO] (5), upon crystallization from DMSO. Bismuth oxido clusters 3 and 5 crystallize in the triclinic space group P1 both with two crystallographically independent molecules in the asymmetric unit. The following lattice parameters are observed: 3, a = 20.3804(10) Å, b = 20.3871(9) Å, c = 34.9715(15) Å, α = 76.657(4)°, β = 73.479(4)°, γ = 60.228(5)°, V = 12021.7(9) Å(3); 5, a = 20.0329(4) Å, b = 20.0601(4) Å, c = 34.3532(6) Å, α = 90.196(1)°, β = 91.344(2)°, γ = 119.370(2)°, V = 12025.8(4) Å(3). Differences in the number of DMSO molecules (coordinated and noncoordinated) and ligand (nitrate, DMSO) coordination modes are observed.

  20. γ irradiation induced effects on bismuth active centres and related photoluminescence properties of Bi/Er co-doped optical fibres

    Science.gov (United States)

    Sporea, D.; Mihai, L.; Neguţ, D.; Luo, Yanhua; Yan, Binbin; Ding, Mingjie; Wei, Shuen; Peng, Gang-Ding

    2016-07-01

    We investigate the effects of γ irradiation on bismuth active centres (BACs) and related photoluminescence properties of bismuth/erbium co-doped silica fibre (BEDF), [Si] ~28, [Ge] ~1.60, [Al] ~0.10, [Er] ~ BACs and their photoluminescence performance, as important changes in absorption and emission properties associated with the 830 nm pump produces the direct evidence of γ irradiation effects on BAC-Si. We notice that the saturable to unsaturable absorption ratio at pump wavelength could be increased with high dose γ irradiation, indicating that emission and pump efficiency could be increased by γ irradiation. Our experimental results also reveal good radiation survivability of the BEDF under low and moderate γ irradiation. Our investigation suggests the existence of irradiation related processing available for tailoring the photoluminescence properties and performance of bismuth doped/co-doped fibres.

  1. Bismuth centred magnetic perovskite: A projected multiferroic

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Asish K., E-mail: asish.k@gmail.com [Discipline of Physics, Indian Institute of Information Technology, Design and Manufacturing, Dumna Airport Road, Jabalpur 482005 (India); Seikh, Md. Motin [Department of Chemistry, Visva-Bharati University, Santiniketan, West Bengal 731235 (India); Nautiyal, Pranjal [Discipline of Mechanical Engineering, Indian Institute of Information Technology, Design and Manufacturing, Dumna Airport Road, Jabalpur 482005 (India)

    2015-03-15

    In recent time substantial attention has been initiated to understand the physics behind multiferroism and to design new multiferroic materials. BiMnO{sub 3} and BiFeO{sub 3} are the well-studied Bi-centred multiferroic oxides. BiMnO{sub 3} is a ferromagnetic–ferroelectric (metastable) phase and require drastic conditions to synthesize. However, lanthanum substituted BiMnO{sub 3} phases stabilized at ambient pressure. It is thus of major importance to increase the number of ferromagnetic perovskites with Bi cations that could be designed under ambient conditions. In this article, we have presented an up to date report of investigations on Bi-centred magnetic perovskites, a prospective material for multiferroic application. Central focus is concentrated on La{sub 0.5}Bi{sub 0.5}MnO{sub 3} perovskite with various substitutions at different levels. A few of these perovskites are found to be of practical importance e.g. La{sub 0.5}Bi{sub 0.5}Mn{sub 0.67}Co{sub 0.33}O{sub 3} with high dielectric permittivity coupled with ferromagnetism. A comprehensive analysis of different physical functionalities and their interrelation for a wide range of compositions of these Bi-centred perovskites is presented. It has been found that the complex magnetic behaviour originates from mixed valence metal ions. The ferroelectricity is associated with the 6s{sup 2} lone pair of Bi{sup 3+} cations. The magnetic ground state influences the dielectric properties reflecting the multiferroism in a single material. - Highlights: • Multiferroics have attracted increasing attention due to their possible device applications. • Bismuth centred magnetic perovskite is one kind of such promising multiferroic materials. • Ferromagnetic Bi-perovskites, which are synthesized at ambient conditions, have been discussed.

  2. Effect of Bismuth Oxide on the Microstructure and Electrical Conductivity of Yttria Stabilized Zirconia

    Directory of Open Access Journals (Sweden)

    Liwei Liu

    2016-03-01

    Full Text Available Bismuth oxide (Bi2O3-doped yttria-stabilized zirconia (YSZ were prepared via the solid state reaction method. X-ray diffraction and electron diffraction spectroscopy results indicate that doping with 2 mol% Bi2O3 and adding 10 mol% yttria result in a stable zirconia cubic phase. Adding Bi2O3 as a dopant increases the density of zirconia to above 96%, while reducing its normal sintering temperature by approximately 250 °C. Moreover, electrical impedance analyses show that adding Bi2O3 enhances the conductivity of zirconia, improving its capability as a solid electrolyte for intermediate or even lower temperatures.

  3. Effect of Bismuth Oxide on the Microstructure and Electrical Conductivity of Yttria Stabilized Zirconia.

    Science.gov (United States)

    Liu, Liwei; Zhou, Zheng; Tian, He; Li, Jixue

    2016-03-14

    Bismuth oxide (Bi2O3)-doped yttria-stabilized zirconia (YSZ) were prepared via the solid state reaction method. X-ray diffraction and electron diffraction spectroscopy results indicate that doping with 2 mol% Bi2O3 and adding 10 mol% yttria result in a stable zirconia cubic phase. Adding Bi2O3 as a dopant increases the density of zirconia to above 96%, while reducing its normal sintering temperature by approximately 250°C. Moreover, electrical impedance analyses show that adding Bi2O3 enhances the conductivity of zirconia, improving its capability as a solid electrolyte for intermediate or even lower temperatures.

  4. Shielding design studies for a neutron irradiator system based on a 252Cf source.

    Science.gov (United States)

    da Silva, A X; Crispim, V R

    2001-01-01

    This study aims to investigate a shielding design against neutrons and gamma rays from a source of 252Cf, using Monte Carlo simulation. The shielding materials studied were borated polyethylene, borated-lead polyethylene and stainless steel. The Monte Carlo code MCNP4B was used to design shielding for 252Cf based neutron irradiator systems. By normalising the dose equivalent rate values presented to the neutron production rate of the source, the resulting calculations are independent of the intensity of the actual 252Cf source. The results show that the total dose equivalent rates were reduced significantly by the shielding system optimisation.

  5. Shielding optimization studies for the detector systems of the Superconducting Super Collider

    Energy Technology Data Exchange (ETDEWEB)

    Slater, C.O.; Lillie, R.A.; Gabriel, T.A.

    1994-09-01

    Preliminary shielding optimization studies for the Superconducting Super Collider`s Solenoidal Detector Collaboration detector system were performed at the Oak Ridge National Laboratory in 1993. The objective of the study was to reduce the neutron and gamma-ray fluxes leaving the shield to a level that resulted in insignificant effects on the functionality of the detector system. Steel and two types of concrete were considered as components of the shield, and the shield was optimized according to thickness, weight, and cost. Significant differences in the thicknesses, weights, and costs were noted for the three optimization parameters. Results from the study are presented.

  6. Shielding the a. c. magnetic fields in bitter-type magnets

    Energy Technology Data Exchange (ETDEWEB)

    Alekseevskii, N.E.; Fuchs, G.; Glinski, M.; Gostishchev, V. (International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw (Poland))

    1984-01-01

    The results of shielding efficiency investigations of various shields for a.c. component of magnetic field generated by Bitter magnets are presented. The best effects were obtained for shields made of In with RRR approximately 10/sup 5/ and for single-turn V/sub 3/Ga solenoid shorted by Cu wire. In both cases the a.c. component was decreased about ten times in field of 14 T.

  7. LOW-FREQUENCY MAGNETIC FIELD SHIELDING BY A CIRCULAR PASSIVE LOOP AND CLOSED SHELLS

    Directory of Open Access Journals (Sweden)

    V.S. Grinchenko

    2016-05-01

    Full Text Available Purpose. To analyze the shielding factors for a circular passive loop and conductive closed shells placed in a homogeneous low-frequency magnetic field. Methodology. We have obtained simplified expressions for the shielding factors for a circular passive loop and a thin spherical shell. In addition, we have developed the numerical model of a thin cubical shell in a magnetic field, which allows exploring its shielding characteristics. Results. We have obtained dependences of the shielding factors for passive loops and shells on the frequency of the external field. Analytically determined frequency of the external magnetic field, below which field shielding of a passive loop is expedient to use, above which it is advisable to use a shielding shell.

  8. Structural Integrity Evaluation of Cold Neutron Laboratory Building by Design Change of Guide Shielding Room

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Sangik; Kim, Youngki; Kim, Harkrho

    2007-06-15

    This report summarizes the results of the structural integrity evaluation for the cold neutron laboratory building by design change of guide shielding room. The design of the guide shielding room was changed by making its structure members in normal concrete (2.3 g/cc) instead of heavy concrete (3.5 g/cc) because the heavy concrete could be not supplied to meet its design specification. Therefore, it was decided that the guide shielding room is made of the normal concrete. And, the shielding performance of the normal concrete was recalculated to confirm satisfying its design specification, which is of a 9000 zone according to HANARO radiation region classification. The change makes the shielding wall thicker than existing design, and then it is caused to qualify the structural integrity evaluation of the CNLB. Finally, the structural integrity of the CNLB was re-evaluated by considering the design change of the guide shielding room.

  9. Influence of the ionization-energy losses of high-energy bismuth ions on the development of helium blisters in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Reutov, V. F., E-mail: reutov@jinr.ru; Dmitriev, S. N.; Sohatsky, A. S. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research (Russian Federation); Zaluzhnyi, A. G. [National Research Nuclear University “MEPhi” (Moscow Engineering Physics Institute) (Russian Federation)

    2015-10-15

    Understanding the behavior of helium in solids under conditions of intense ionizing radiation is of particular interest in solving many problems of nuclear, fusion, and space materials science and also in microelectronics. The observed effect of suppressing the formation of helium blisters on the surface of helium ion-doped silicon as a result of irradiation with high-energy bismuth ions is reported in this publication. It is suggested that a possible decrease in the concentration of helium atoms in silicon is due to their radiationinduced desorption from the area of doping in terms of the high-impact ionization of bismuth ions.

  10. Radiation shielding for diagnostic radiology.

    Science.gov (United States)

    Martin, Colin J

    2015-07-01

    Scattered radiation makes up the majority of the stray radiation field around an X-ray unit. The scatter is linked to the amount of radiation incident on the patient. It can be estimated from quantities used to assess patient dose such as the kerma-area product, and factors have been established linking this to levels of scattered radiation for radiography and fluoroscopy. In radiography shielding against primary radiation is also needed, but in other modalities this is negligible, as the beam is intercepted by the image receptor. In the same way scatter from CT can be quantified in terms of dose-length product, but because of higher radiation levels, exposure to tertiary scatter from ceilings needs to be considered. Transmission requirements are determined from comparisons between calculated radiation levels and agreed dose criteria, taking into account the occupancy of adjacent areas. Thicknesses of shielding material required can then be calculated from simple equations.

  11. Facility target insert shielding assessment

    Energy Technology Data Exchange (ETDEWEB)

    Mocko, Michal [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-06

    Main objective of this report is to assess the basic shielding requirements for the vertical target insert and retrieval port. We used the baseline design for the vertical target insert in our calculations. The insert sits in the 12”-diameter cylindrical shaft extending from the service alley in the top floor of the facility all the way down to the target location. The target retrieval mechanism is a long rod with the target assembly attached and running the entire length of the vertical shaft. The insert also houses the helium cooling supply and return lines each with 2” diameter. In the present study we focused on calculating the neutron and photon dose rate fields on top of the target insert/retrieval mechanism in the service alley. Additionally, we studied a few prototypical configurations of the shielding layers in the vertical insert as well as on the top.

  12. Thermal-hydraulic Analysis in the Pool of PGSFR including the Shielding

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung; Lee, Taeho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Various design issues relate to this region, and one of them is thermal-hydraulic behavior when shielding exists inside the reactor vessel. The shielding is used for the blockage of the radiation emitted by the reactor core. The shielding is installed at the Intermediate Heat eXchanger (IHX), core shroud, and redan region at the top of core. However, this structure disturbs the normal flow path and heat transfer of the primary heat transfer system. In this study, the multi-dimensional thermal-hydraulic characteristics in the pool of PGSFR including the shielding are analyzed. Also these results are compared to a case in which no shielding is installed. A thermal-hydraulic analysis in the pool of the PGSFR considering the shielding structure are performed using STAR-CCM+. The internal major components of the pool inside are modeled, and calculations are performed with a normal operation condition. Also, these results are compared to a no shielding case. The flow and temperature changes owing to the shielding structure at a redan inside are shown, but the overall flow and temperature distributions in both cases are substantially similar. Also the physical properties such as the flow rate, temperature, and static pressure at each major point are almost the same. These results are utilized in the arrangement of the reactor internal structure and design of the shielding structure.

  13. Preparation of Bismuth Subcarbonate by Ball-milling Coversion Method Using Bismuth Oxide%球磨转化法由氧化铋制取次碳酸铋研究

    Institute of Scientific and Technical Information of China (English)

    蒋叶; 唐朝波; 唐谟堂; 杨声海; 何静; 陈永明; 杨建广

    2013-01-01

      针对次碳酸铋传统制备工艺存在试剂消耗大、产生大量氨氮废水等问题,提出了一种用氧化铋和碳酸氢铵机械球磨直接制备次碳酸铋新工艺,考察了碳酸氢铵浓度、液固体积质量比、球料质量比、反应时间对氧化铋转化率的影响。结果表明,在碳酸氢铵浓度为2.5 mol/L、液固体积质量比为7∶1、球料质量比为8∶1、反应时间为2 h、室温条件下,氧化铋转化率达93.23%。该工艺流程简短,成本低,转化母液可循环利用,解决了传统工艺试剂消耗大及产生大量氨氮废水等问题。%A new process for preparation of bismuth subcarbonate by ball-milling coversion method using bismuth oxide has been proposed .T he effects of ammonium bicarbonate concentrate ,liquid/solid ratio ,mass ratio of ball to bismuth oxide and milling time on conversion rate of bismuth oxide were ex-amined .The results showed that the direct conversion rate of bismuth oxide colud reach 93 .23% under the optimum conditions which the ammonium bicarbonate concentration was 2 .5 mol/L ,liquid/solid ratio was 7∶1 ,mass ratio of ball to bismuth oxide was 8∶1 ,and milling 2 hours at room temperature . The process has the advantage of short procedure ,cheap reactant ,low cost ,and mother liquid can be u-tilized circularly .

  14. Paramagnetism shielding in drilling fluid

    OpenAIRE

    Li,Zhuo

    2013-01-01

    In drilling operations, drilling fluid containing magnetic materials is used when drilling a well. The materials can significantly shield the Earth’s magnetic field as measured by magnetic sensors inside the drilling strings. The magnetic property of the drilling fluid is one of the substantial error sources for the determination of magnetic azimuth for wellbores. Both the weight material, cuttings, clay and other formation material plus metal filings from the tubular wear m...

  15. Light shield for solar concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Plesniak, Adam P.; Martins, Guy L.

    2014-08-26

    A solar receiver unit including a housing defining a recess, a cell assembly received in the recess, the cell assembly including a solar cell, and a light shield received in the recess and including a body and at least two tabs, the body defining a window therein, the tabs extending outward from the body and being engaged with the recess, wherein the window is aligned with the solar cell.

  16. Highly monodisperse bismuth nanoparticles and their three-dimensional superlattices.

    Science.gov (United States)

    Yarema, Maksym; Kovalenko, Maksym V; Hesser, Günter; Talapin, Dmitri V; Heiss, Wolfgang

    2010-11-01

    A simple and reproducible synthesis of highly monodisperse and ligand-protected bismuth nanoparticles (Bi NPs) is reported. The size of the single-crystalline and spherically shaped NPs is controlled between 11 and 22 nm mainly by the reaction temperature. The high uniformity of the NPs allows their self-assembly into long-range-ordered two- and three-dimensional superstructures.

  17. Ultrafast electronic dynamics in laser-excited crystalline bismuth

    Directory of Open Access Journals (Sweden)

    Chekalin S.

    2013-03-01

    Full Text Available Femtosecond spectroscopy was applied to capture complex dynamics of non equilibrium electrons in bismuth. Data analysis reveals significant wavevector dependence of electron-hole and electron-phonon coupling strength along the Γ-T direction of the Brillouin zone

  18. Phase transition of bismuth telluride thin films grown by MBE

    DEFF Research Database (Denmark)

    Fülöp, Attila; Song, Yuxin; Charpentier, Sophie

    2014-01-01

    A previously unreported phase transition between Bi2Te3 and Bi4Te3 in bismuth telluride grown by molecular beam epitaxy is recorded via XRD, AFM, and SIMS observations. This transition is found to be related to the Te/Bi beam equivalent pressure (BEP) ratio. BEP ratios below 17 favor the formation...

  19. Oxygen semi-permeability of erbia-stabilized bismuth oxide

    NARCIS (Netherlands)

    Bouwmeester, H.J.M.; Kruidhof, H.; Burggraaf, A.J.; Gellings, P.J.

    1992-01-01

    The isothermal permeability of oxygen through sintered dense disks of bismuth oxide stabilized with 25 mol% erbia (BE25) has been studied at 610–810°C and oxygen pressures of 0.0001–1 atm. It is concluded that the permeating flux is rate limited both by solid state diffusion of electron holes and by

  20. Bismuth-lead oxide, a new highly conductive oxygen materials

    NARCIS (Netherlands)

    Honnart, F.; Boivin, J.C.; Thomas, D.; Vries, de K.J.

    1983-01-01

    The transport properties of an oxygen-deficient solid solution containing lead and bismuth oxides have been investigated. The conductivity is larger than 1 (ω× cm)−1 at 600 °C. Thermogalvanic measurements confirm that no significant electronic contribution occurs in the range 1–10−3atm p O2. The hea

  1. High ionic conductivity in confined bismuth oxide-based heterostructures

    DEFF Research Database (Denmark)

    Sanna, Simone; Esposito, Vincenzo; Christensen, Mogens

    2016-01-01

    Bismuth trioxide in the cubic fluorite phase (δ-Bi2O3) exhibits the highest oxygen ionic conductivity. In this study, we were able to stabilize the pure -Bi2O3 at low temperature with no addition of stabilizer but only by engineering the interface, using highly coherent heterostructures made...

  2. Nanometer bismuth oxide produced by resistance heating vapor oxidation

    Institute of Scientific and Technical Information of China (English)

    HU Han-xiang; QIU Ke-qiang

    2006-01-01

    Bismuth oxide has wide applications in superconductive material, photoelectric material, electronic ceramic, electrolyte, and catalysts. To produce ultrafine bismuth oxide powders, some costly heating sources, such as plasma, high frequency induction, electron beam or laser, have to be used in the conventional vapor oxidation methods. The vapor oxidation method was improved by adding a reducing agent in the reaction system, where heating source was resistance tubular oven, instead of special heat source requirement. Nanometer bismuth oxide was prepared at 1 000-1 140 ℃, and the particle characteristics were investigated by XRD, SEM, DTA, laser sedimentograph. With low oxygen concentration (less than 20%) in the carrier gas, the bismuth oxide particle was near-sphere β-Bi2O3 with uniform and fine particle size (d0.5=65 nm, GSD=1.42); while with higher oxygen content (more than 50%), the powders were mixture of Bi2O2CO3 and β-Bi2O3.

  3. Polymeric architectures of bismuth citrate based on dimeric building blocks

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Four bismuth complexes, (H2En)[Bi2(cit)2(H2O)4/3]·(H2O)x (1), (H2En)3[Bi2(cit)2Cl4]·(H2O)x (2), (HPy)2[Bi2(cit)2(H2O)8/5]·(H2O)x (3) and (H2En)[Bi2(cit)2](H2O)x (4) [cit = citrate4-; En = ethylenediamine; Py = pyridine] have been synthesized and crystallized. The crystal structures reveal that the basic building blocks in all of these complexes are bismuth citrate dimeric units which combine to form polymeric architectures. The embedded protonated ethylenediamine and pyridine moieties in the polymeric frameworks have been identified by X-ray crystallography and solid-state cross polarization/magic angle spinning (CP/MAS) 13C NMR. Based on the framework of complex 1, a structural model of a clinically used antiulcer drug, ranitidine bismuth citrate (RBC) was generated. The behavior of the protonated amine-bismuth citrate complexes in acidic aqueous solution has been studied by electrospray ionization-mass spectrometry (ESI-MS).

  4. REMOVAL OF CERTAIN FISSION PRODUCT METALS FROM LIQUID BISMUTH COMPOSITIONS

    Science.gov (United States)

    Dwyer, O.E.; Howe, H.E.; Avrutik, E.R.

    1959-11-24

    A method is described for purifying a solution of urarium in liquid bismuth containing at least one metal from the group consisting of selenium, tellurium, palladium, ruthenium, rhodium, niobium, and zirconium. The solution is contacted with zinc in an inert atmosphere to form a homogeneous melt, a solid zinc phase is formed, and the zinc phase containing the metal is separated from the melt.

  5. Ultrafast electron diffraction studies of optically excited thin bismuth films

    Energy Technology Data Exchange (ETDEWEB)

    Rajkovic, Ivan

    2008-10-21

    This thesis contains work on the design and the realization of an experimental setup capable of providing sub-picosecond electron pulses for ultrafast electron diffraction experiments, and performing the study of ultrafast dynamics in bismuth after optical excitation using this setup. (orig.)

  6. Discovery of the thallium, lead, bismuth, and polonium isotopes

    Science.gov (United States)

    Fry, C.; Thoennessen, M.

    2013-05-01

    Forty-two thallium, forty-two lead, forty-one bismuth, and forty-two polonium isotopes have so far been observed; the discovery of these isotopes is described. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  7. Discovery of the thallium, lead, bismuth, and polonium isotopes

    CERN Document Server

    Fry, C

    2012-01-01

    Currently, forty-two thallium, forty-two lead, forty-one bismuth, and forty-two polonium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  8. Bismuth Ferrite for Active Control of Surface Plasmon Polariton Modes

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2014-01-01

    We propose and investigate several layouts of m etal-insulator-metal waveguide with active core which can be utilized for dynamic switching in photonic integrated circuits. The active material, bismuth ferrite (BiFeO3), is sandwiched between metal plates and changes i ts refractive index through ...

  9. ATLAS Award for Shield Supplier

    CERN Multimedia

    2004-01-01

    ATLAS technical coordinator Dr. Marzio Nessi presents the ATLAS supplier award to Vojtech Novotny, Director General of Skoda Hute.On 3 November, the ATLAS experiment honoured one of its suppliers, Skoda Hute s.r.o., of Plzen, Czech Republic, for their work on the detector's forward shielding elements. These huge and very massive cylinders surround the beampipe at either end of the detector to block stray particles from interfering with the ATLAS's muon chambers. For the shields, Skoda Hute produced 10 cast iron pieces with a total weight of 780 tonnes at a cost of 1.4 million CHF. Although there are many iron foundries in the CERN member states, there are only a limited number that can produce castings of the necessary size: the large pieces range in weight from 59 to 89 tonnes and are up to 1.5 metres thick.The forward shielding was designed by the ATLAS Technical Coordination in close collaboration with the ATLAS groups from the Czech Technical University and Charles University in Prague. The Czech groups a...

  10. Vibration Monitoring Using Fiber Optic Sensors in a Lead-Bismuth Eutectic Cooled Nuclear Fuel Assembly

    OpenAIRE

    Ben De Pauw; Alfredo Lamberti; Julien Ertveldt; Ali Rezayat; Katrien van Tichelen; Steve Vanlanduit; Francis Berghmans

    2016-01-01

    Excessive fuel assembly vibrations in nuclear reactor cores should be avoided in order not to compromise the lifetime of the assembly and in order to prevent the occurrence of safety hazards. This issue is particularly relevant to new reactor designs that use liquid metal coolants, such as, for example, a molten lead-bismuth eutectic. The flow of molten heavy metal around and through the fuel assembly may cause the latter to vibrate and hence suffer degradation as a result of, for example, fr...

  11. Performance of neutron activation analysis in the evaluation of bismuth iodide purification methodology

    Energy Technology Data Exchange (ETDEWEB)

    Armelin, Maria Jose A.; Ferraz, Caue de Mello; Hamada, Margarida M., E-mail: marmelin@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Lab. de Analise por Ativacao Neutronica

    2015-07-01

    Bismuth tri-iodide (BrI{sub 3}) is an attractive material for using as a semiconductor. In this paper, BiI{sub 3} crystals have been grown by the vertical Bridgman technique using commercially available powder. The impurities were evaluated by instrumental neutron activation analysis (INAA). The results show that INAA is an analytical method appropriate for monitoring the impurities of: Ag, As, Br, Cr, K, Mo, Na and Sb in the various stages of the BiI{sub 3} purification methodology. (author)

  12. Shielding Performance Measurements of Spent Fuel Transportation Container

    Directory of Open Access Journals (Sweden)

    SUN Hong-chao

    2015-11-01

    Full Text Available The safety supervision of radioactive material transportation package has been further stressed and implemented. The shielding performance measurements of spent fuel transport container is the important content of supervision. However, some of the problems and difficulties reflected in practice need to be solved, such as the neutron dose rate on the surface of package is too difficult to measure exactly, the monitoring results are not always reliable, etc. The monitoring results using different spectrometers were compared and the simulation results of MCNP runs were considered. An improvement was provided to the shielding performance measurements technique and management of spent fuel transport.

  13. A Dynamic Discrete Dislocation Plasticity study of elastodynamic shielding of stationary cracks

    Science.gov (United States)

    Gurrutxaga-Lerma, B.; Balint, D. S.; Dini, D.; Sutton, A. P.

    2017-01-01

    Employing Dynamic Discrete Dislocation Plasticity (D3P), an elastodynamic analysis of the shielding of a stationary crack tip by dislocations is studied. Dislocations are generated via Frank-Read sources, and make a negligible contribution to the shielding of the crack tip, whereas dislocations generated at the crack tip via homogeneous nucleation dominate the shielding. Their effect is found to be highly localised around the crack, leading to a magnification of the shielding when compared to time-independent, elastostatic predictions. The resulting attenuation of KI(t) is computed, and is found to be directly proportional to the applied load and to √{ t }.

  14. Influence of the gas shielding method upon the properties of the weld joints

    Science.gov (United States)

    Chinakhov, D. A.; Sapozhkov, A. S.

    2016-11-01

    The authors consider the influence of the gas shielding method under consumable electrode welding and double-jet gas shielding together with its influence upon the processes in the arc zone and the properties of weld joints from high-strength alloyed 30HGSA steel. The authors provide the results of recent experimental research on weld joints properties improvement through changing the gas dynamics of the active shielding gas. It was established that the jet of active shielding gas has a considerable gas-dynamic influence upon weld joints formation, chemical composition, structure and properties of the weld joints from high-strength alloyed steels.

  15. MicroShield/ISOCS gamma modeling comparison.

    Energy Technology Data Exchange (ETDEWEB)

    Sansone, Kenneth R

    2013-08-01

    Quantitative radiological analysis attempts to determine the quantity of activity or concentration of specific radionuclide(s) in a sample. Based upon the certified standards that are used to calibrate gamma spectral detectors, geometric similarities between sample shape and the calibration standards determine if the analysis results developed are qualitative or quantitative. A sample analyzed that does not mimic a calibrated sample geometry must be reported as a non-standard geometry and thus the results are considered qualitative and not quantitative. MicroShieldR or ISOCSR calibration software can be used to model non-standard geometric sample shapes in an effort to obtain a quantitative analytical result. MicroShieldR and Canberras ISOCSR software contain several geometry templates that can provide accurate quantitative modeling for a variety of sample configurations. Included in the software are computational algorithms that are used to develop and calculate energy efficiency values for the modeled sample geometry which can then be used with conventional analysis methodology to calculate the result. The response of the analytical method and the sensitivity of the mechanical and electronic equipment to the radionuclide of interest must be calibrated, or standardized, using a calibrated radiological source that contains a known and certified amount of activity.

  16. EMPLACEMENT DRIFT SHIELDING CALCULATION

    Energy Technology Data Exchange (ETDEWEB)

    A. Nielsen

    1999-10-13

    The purpose of this analysis is to determine the structural response of a TRIGA Department of Energy (DOE) spent nuclear fuel (SNF) codisposal canister placed in a 5-Defense High Level Waste (DHLW) waste package (WP) and subjected to a tipover design basis event (DBE) dynamic load; the results will be reported in terms of displacements and stress magnitudes. This activity is associated with the WP design.

  17. Novel shielding materials for space and air travel.

    Science.gov (United States)

    Vana, N; Hajek, M; Berger, T; Fugger, M; Hofmann, P

    2006-01-01

    The reduction of dose onboard spacecraft and aircraft by appropriate shielding measures plays an essential role in the future development of space exploration and air travel. The design of novel shielding strategies and materials may involve hydrogenous composites, as it is well known that liquid hydrogen is most effective in attenuating charged particle radiation. As precursor for a later flight experiment, the shielding properties of newly developed hydrogen-rich polymers and rare earth-doped high-density rubber were tested in various ground-based neutron and heavy ion fields and compared with aluminium and polyethylene as reference materials. Absorbed dose, average linear energy transfer and gamma-equivalent neutron absorbed dose were determined by means of LiF:Mg,Ti thermoluminescence dosemeters and CR-39 plastic nuclear track detectors. First results for samples of equal aerial density indicate that selected hydrogen-rich plastics and rare-earth-doped rubber may be more effective in attenuating cosmic rays by up to 10% compared with conventional aluminium shielding. The appropriate adaptation of shielding thicknesses may thus allow reducing the biologically relevant dose. Owing to the lower density of the plastic composites, mass savings shall result in a significant reduction of launch costs. The experiment was flown as part of the European Space Agency's Biopan-5 mission in May 2005.

  18. Deep-penetration calculations in concrete and iron for shielding of proton therapy accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Sheu, Rong-Jiun, E-mail: rjsheu@mx.nthu.edu.tw [Institute of Nuclear Engineering and Science, National Tsing Hua University, 101 Sec. 2, Kung Fu Road, Hsinchu 300, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, 101 Sec. 2, Kung Fu Road, Hsinchu 300, Taiwan (China); National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 300, Taiwan (China); Chen, Yen-Fu [Department of Engineering and System Science, National Tsing Hua University, 101 Sec. 2, Kung Fu Road, Hsinchu 300, Taiwan (China); Lin, Uei-Tyng [Institute of Radiological Sciences, Tzu Chi College of Technology, 880 Sec. 2, Chien-Kuo Road, Hualien 970, Taiwan (China); Jiang, Shiang-Huei [Institute of Nuclear Engineering and Science, National Tsing Hua University, 101 Sec. 2, Kung Fu Road, Hsinchu 300, Taiwan (China); Department of Engineering and System Science, National Tsing Hua University, 101 Sec. 2, Kung Fu Road, Hsinchu 300, Taiwan (China)

    2012-06-01

    Proton accelerators in the energy range of approximately 200 MeV have become increasingly popular for cancer treatment in recent years. These proton therapy facilities usually involve bulky concrete or iron in their shielding design or accelerator structure. Simple shielding data, such as source terms or attenuation lengths for various proton energies and materials are useful in designing accelerator shielding. Understanding the appropriateness or uncertainties associated with these data, which are largely generated from Monte Carlo simulations, is critical to the quality of a shielding design. This study demonstrated and investigated the problems of deep-penetration calculations on the estimation of shielding parameters through an extensive comparison between the FLUKA and MCNPX calculations for shielding against a 200-MeV proton beam hitting an iron target. Simulations of double-differential neutron production from proton bombardment were validated by comparison with experimental data. For the concrete shielding, the FLUKA calculated depth-dose distributions were consistent with the MCNPX results, except for some discrepancies in backward directions. However, for the iron shielding, if FLUKA is used inappropriately then overestimation of neutron attenuation can be expected as shown by this work because of the multigroup treatment for low-energy neutrons in FLUKA. Two neutron energy group structures, three degrees of self-shielding correction, and two iron compositions were considered in this study. Significant variation of the resulting attenuation lengths indicated the importance of problem-dependent multigroup cross sections and proper modeling of iron composition in deep-penetration calculations.

  19. Study on surface modification of bismuth nanoparticles%纳米铋的表面改性研究

    Institute of Scientific and Technical Information of China (English)

    罗洁; 卢业玉; 余林

    2012-01-01

    The adsorption amounts of three types of surfactants, i.e.stearic acid (SA),oleic acid (OA), and cetyltrimethylam-monium bromide (CTAB), on the surface of bismuth nanoparticles were investigated, in order to select the best surface modifier. Effects of various factors on modification of bismuth nanoparticles with stearic acid were discussed, and optimal modification conditions were obtained as follows: dosage of stearic acid was 10% (relative to the mass of bismuth powder) ,pH=5~6, and modification time was 1 h.Under these conditions,the modified bismuth nanoparticles had good wetting and dispersity in liquid paraffin and the powder was changed from hydrophilicity to hydrophobicity.FT-IR and XRD results showed the organic long-chain group of stearic acid grafted onto the surface of bismuth nanoparticles by chemical bonds; the crystal type of bismuth nanoparticles was not changed, but the grain diameter was decreased periodically.%测定了3种表面活性剂硬脂酸(SA)、油酸(OA)和十六烷基三甲基溴化铵(CTAB)在纳米铋表面的吸附量,进而选出最佳表面改性剂.研究了硬脂酸改性纳米铋粉各种因素对改性效果的影响,确定最佳工艺条件:改性剂用量为10%(相对于铋粉质量),pH为5~6,改性时间为1h.此条件下,改性后的纳米铋粉能在液体石蜡中润湿和分散,表明改性后粉体由亲水性变为亲油性.红外光谱(FT-IR)分析及X射线衍射(XRD)分析结果表明,硬脂酸有机长链基团成功地以化学键结合在纳米铋表面,改性后的铋粒子未发生晶型改变,只是粒径略有降低.

  20. Lab-on-a-Chip Sensor with Evaporated Bismuth Film Electrode for Anodic Stripping Voltammetry of Zinc

    Science.gov (United States)

    Kang, Wenjing; Pei, Xing; Yue, Wei; Bange, Adam; Heineman, William R.; Papautsky, Ian

    2013-01-01

    In this work, we report on the development of a lab-on-a-chip electrochemical sensor that uses an evaporated bismuth electrode to detect zinc using square wave anodic stripping voltammetry. The microscale electrochemical cell consists of a bismuth working electrode, an integrated silver/silver chloride reference electrode, and a gold auxiliary electrode. The sensor demonstrated linear response in 0.1 M acetate buffer at pH 6 with zinc concentrations ranging from 1 μM to 30 μM and a calculated detection limit of 60 nM. The sensor was also able to successfully detect zinc in a bovine serum extract and the results were verified with independent AAS measurements. These results demonstrate the advantageous qualities of this lab-on-a-chip electrochemical sensor for clinical applications, which include a small sample volume (μL scale), reduced cost, short response time and high accuracy at low concentrations of analyte. PMID:24436575

  1. Bismuth tri-iodide radiation detector development

    Science.gov (United States)

    Gokhale, Sasmit S.

    Bismuth tri-iodide is an attractive material for room temperature radiation detection. BiI3 demonstrates a number of properties that are apt for semiconductor radiation detection, especially gamma ray spectroscopy. The high atomic number (ZBi = 83 and ZI = 53) and the relatively high density (5.78 g/cm3) cause the material to have good photon stopping power, while the large band-gap (1.67 eV ) allows it to function as a room temperature radiation detector without any cooling mechanism. This work presents the fabrication and characterization of BiI3 radiation detectors. For the purpose of this research detectors were fabricated by cutting BiI3 crystal boules, followed by mechanical and chemical surface treatments. Detectors with various electrode geometries enabling single polarity charge sensing were fabricated. The electrical characteristics and the radiation response of the detectors were measured. The radiation response measurement was performed at room temperature using a 241Am alpha particle source and a 241Am sealed gamma-ray source. The spectral resolutions of the detectors varied from 2.09% - 6.1% for 59.5 keV gamma-rays and between 26% - 40% for 5.48 MeV alpha particles. Charge carrier properties such as the electron and hole mobility and lifetime were also estimated. The electron mobility for an ultrapure BiI 3 detector was estimated to be approximately 433 cm 2/Vs while that for antimony doped BiI3 was estimated to be around 956 cm2/Vs and the mobility-lifetime product for electrons was estimated to be around 5.44 x 10-4 cm 2/V. Detector simulation was performed using the Monte Carlo simulation code MCNP5. A Matlab script which incorporates charge carrier trapping and statistical variation was written to generate a gamma-ray spectrum from the simulated energy deposition spectra. Measured and simulated spectra were compared to extract the charge carrier mobility-lifetime products, which for electrons and holes were estimated to be 5 x 10-3 cm2/V and 1.3 x

  2. Texture and anisotropy of ferroelectric bismuth titanate

    Science.gov (United States)

    Jones, Jacob Leo

    Ferroelectric bismuth titanate, Na0.5Bi4.5 Ti4O15, is a piezoelectric ceramic used as an electromechanical sensor in high temperature environments (T piezoelectric constant, d33, is relatively low in randomly oriented ceramics. Crystallographic texturing is often employed to increase the piezoelectric constant because the spontaneous polarization axes of the grains are better aligned. This research distinguishes between the crystallographic texture induced to the grains from tape casting and crystallographic texture induced to the ferroelectric domains from electrical poling. Novel quantitative approaches describe texture of both types independently using conventional and synchrotron X-ray sources as well as time-of-flight neutron diffraction with multiple detectors. Furthermore, methods are developed to describe the combined effect of a ferroelectric texture superimposed on a paraelectric texture. Texture of the paraelectric crystallographic axes was induced by novel processing approaches. An alternative to using plate-shaped template particles was developed utilizing calcined powder. Paraelectric texture develops from particle settling and strong surface energy anisotropy during sintering. The 00l textures induced from this process are on the order of two to four multiples of a random distribution. These textures create property anisotropies between the casting plane and normal directions of 6.4 and 5.7 in piezoelectric d33 constant and remanent polarization, respectively. Texture of the ferroelectric crystallographic axes was induced by electrical poling at different temperatures and in different orientations. Ceramics with an initial paraelectric texture can exhibit greater change in the domain volume fractions during electrical poling than randomly oriented ceramics. This is demonstrated by applying novel quantitative approaches to reflection X-ray spectra from many sample directions. Because orthorhombic Na0.5Bi 4.5Ti4O15 has two ferroelectric domains that

  3. Radiation shielding for future space exploration missions

    Science.gov (United States)

    DeWitt, Joel Michael

    weighted figure of merit (WFoM) approach that quantifies the effectiveness of a candidate material to shield space crews from the whole of the space radiation environment. The results of the WFoM approach should prove useful to designers and engineers in seeking alternative materials suitable for the construction of spacecraft or planetary surface habitats needed for long-term space exploration missions. The dosimetric measurements in this study have confirmed the principle of good space radiation shielding design by showing that low-Z¯ materials are most effective at reducing absorbed dose and dose equivalent while high-Z¯ materials are to be avoided. The relatively high WFoMs of carbon composite and lunar- and Martian-regolith composite could have important implications for the design and construction of future spacecraft or planetary surface habitats. The ground-based measurements conducted in this study have validated the heavy ion extension of FLUKA by producing normalized differential LET fluence spectra that are in good agreement with experiment.

  4. Shielding from space radiations

    Science.gov (United States)

    Chang, C. Ken; Badavi, Forooz F.; Tripathi, Ram K.

    1993-01-01

    This Progress Report covering the period of 1 June 1993 to 1 Dec. 1993 presents the development of an analytical solution to the heavy ion transport equation in terms of a one-layer Green's function formalism. The mathematical developments are recasted into an efficient computer code for space applications. The efficiency of this algorithm is accomplished by a nonperturbative technique of extending the Green's function over the solution domain. The code may also be applied to accelerator boundary conditions to allow code validation in laboratory experiments. Results from the isotopic version of the code with 80 isotopes present for a single layer target material, for the case of an iron beam projectile at 600 MeV/nucleon in water is presented.

  5. X-Ray Computed Tomography Inspection of the Stardust Heat Shield

    Science.gov (United States)

    McNamara, Karen M.; Schneberk, Daniel J.; Empey, Daniel M.; Koshti, Ajay; Pugel, D. Elizabeth; Cozmuta, Ioana; Stackpoole, Mairead; Ruffino, Norman P.; Pompa, Eddie C.; Oliveras, Ovidio; hide

    2010-01-01

    The "Stardust" heat shield, composed of a PICA (Phenolic Impregnated Carbon Ablator) Thermal Protection System (TPS), bonded to a composite aeroshell, contains important features which chronicle its time in space as well as re-entry. To guide the further study of the Stardust heat shield, NASA reviewed a number of techniques for inspection of the article. The goals of the inspection were: 1) to establish the material characteristics of the shield and shield components, 2) record the dimensions of shield components and assembly as compared with the pre-flight condition, 3) provide flight infonnation for validation and verification of the FIAT ablation code and PICA material property model and 4) through the evaluation of the shield material provide input to future missions which employ similar materials. Industrial X-Ray Computed Tomography (CT) is a 3D inspection technology which can provide infonnation on material integrity, material properties (density) and dimensional measurements of the heat shield components. Computed tomographic volumetric inspections can generate a dimensionally correct, quantitatively accurate volume of the shield assembly. Because of the capabilities offered by X-ray CT, NASA chose to use this method to evaluate the Stardust heat shield. Personnel at NASA Johnson Space Center (JSC) and Lawrence Livermore National Labs (LLNL) recently performed a full scan of the Stardust heat shield using a newly installed X-ray CT system at JSC. This paper briefly discusses the technology used and then presents the following results: 1. CT scans derived dimensions and their comparisons with as-built dimensions anchored with data obtained from samples cut from the heat shield; 2. Measured density variation, char layer thickness, recession and bond line (the adhesive layer between the PICA and the aeroshell) integrity; 3. FIAT predicted recession, density and char layer profiles as well as bondline temperatures Finally suggestions are made as to future uses

  6. Origin of broad NIR photoluminescence in bismuthate glass and Bi-doped glasses at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Mingying; Zollfrank, Cordt; Wondraczek, Lothar [Lehrstuhl fuer Glas und Keramik, WW3, Friedrich Alexander Universitaet Erlangen-Nuernberg, Martensstrasse 5, D-91058 Erlangen (Germany)], E-mail: mingying.peng@ww.uni-erlangen.de, E-mail: lothar.wondraczek@ww.uni-erlangen.de

    2009-07-15

    Bi-doped glasses with broadband photoluminescence in the near-infrared (NIR) spectral range are presently receiving significant consideration for potential applications in telecommunications, widely tunable fiber lasers and spectral converters. However, the origin of NIR emission remains disputed. Here, we report on NIR absorption and emission properties of bismuthate glass and their dependence on the melting temperature. Results clarify that NIR emission occurs from the same centers as it does in Bi-doped glasses. The dependence of absorption and NIR emission of bismuthate glasses on the melting temperature is interpreted as thermal dissociation of Bi{sub 2}O{sub 3} into elementary Bi. Darkening of bismuthate glass melted at 1300 deg. C is due to the agglomeration of Bi atoms. The presence of Bi nanoparticles is confirmed by transmission electron microscopy, high-resolution energy dispersive x-ray spectroscopy and element distribution mapping. By adding antimony oxide as an oxidation agent to the glass, NIR emission centers can be eliminated and Bi{sup 3+} is formed. By comparing with atomic spectral data, absorption bands at {approx}320 , {approx}500 , 700 , 800 and 1000 nm observed in Bi-doped glasses are assigned to Bi{sup 0} transitions {sup 4}S{sub 3/2}{yields}{sup 2}P{sub 3/2}, {sup 4}S{sub 3/2}{yields}{sup 2}P{sub 1/2}, {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 5/2}, {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 3/2}(2) and {sup 4}S{sub 3/2}{yields}{sup 2}D{sub 3/2}(1), respectively, and broadband NIR emission is assigned to the transition {sup 2}D{sub 3/2}(1){yields}{sup 4}S{sub 3/2}.

  7. Origin of broad NIR photoluminescence in bismuthate glass and Bi-doped glasses at room temperature

    Science.gov (United States)

    Peng, Mingying; Zollfrank, Cordt; Wondraczek, Lothar

    2009-07-01

    Bi-doped glasses with broadband photoluminescence in the near-infrared (NIR) spectral range are presently receiving significant consideration for potential applications in telecommunications, widely tunable fiber lasers and spectral converters. However, the origin of NIR emission remains disputed. Here, we report on NIR absorption and emission properties of bismuthate glass and their dependence on the melting temperature. Results clarify that NIR emission occurs from the same centers as it does in Bi-doped glasses. The dependence of absorption and NIR emission of bismuthate glasses on the melting temperature is interpreted as thermal dissociation of Bi2O3 into elementary Bi. Darkening of bismuthate glass melted at 1300 °C is due to the agglomeration of Bi atoms. The presence of Bi nanoparticles is confirmed by transmission electron microscopy, high-resolution energy dispersive x-ray spectroscopy and element distribution mapping. By adding antimony oxide as an oxidation agent to the glass, NIR emission centers can be eliminated and Bi3+ is formed. By comparing with atomic spectral data, absorption bands at ~320 , ~500 , 700 , 800 and 1000 nm observed in Bi-doped glasses are assigned to Bi0 transitions {}^{4}\\mathrm {S_{3/2}} \\to {}^{2}\\mathrm {P_{3/2}} , {}^{4}\\mathrm {S_{3/2}}\\to {}^{2}\\mathrm {P_{1/2}} , {}^{4}\\mathrm {S_{3/2}}\\to {}^{2}\\mathrm {D_{5/2}} , {}^{4}\\mathrm {S_{3/2}}\\to {}^{2}\\mathrm {D_{3/2}}(2) and {}^{4}\\mathrm {S_{3/2}}\\to {}^{2}\\mathrm {D_{3/2 }}(1) , respectively, and broadband NIR emission is assigned to the transition {}^{2}\\mathrm {D_{3/2}(1)}\\to {}^{4}\\mathrm {S_{3/2}} .

  8. Feasibility of preparing patterned molybdenum coatings on bismuth telluride thermoelectric modules.

    Energy Technology Data Exchange (ETDEWEB)

    Sarobol, Pylin; Hall, Aaron Christopher; Miller, Stephen Samuel; Knight, Marlene E.; LePage, William S.; Sobczak, Catherine Elizabeth.; Wesolowski, Daniel Edward

    2013-09-01

    Molybdenum electrical interconnects for thermoelectric modules were produced by air plasma spraying a 30%CE%BCm size molybdenum powder through a laser-cut Kapton tape mask. Initial feasibility demonstrations showed that the molybdenum coating exhibited excellent feature and spacing retention (~170%CE%BCm), adhered to bismuth-telluride, and exhibited electrical conductivity appropriate for use as a thermoelectric module interconnect. A design of experiments approach was used to optimize air plasma spray process conditions to produce a molybdenum coating with low electrical resistivity. Finally, a molybdenum coating was successfully produced on a fullscale thermoelectric module. After the addition of a final titanium/gold layer deposited on top of the molybdenum coating, the full scale module exhibited an electrical resistivity of 128%CE%A9, approaching the theoretical resistivity value for the 6mm module leg of 112%CE%A9. Importantly, air plasma sprayed molybdenum did not show significant chemical reaction with bismuth-telluride substrate at the coating/substrate interface. The molybdenum coating microstructure consisted of lamellar splats containing columnar grains. Air plasma sprayed molybdenum embedded deeply (several microns) into the bismuth-telluride substrate, leading to good adhesion between the coating and the substrate. Clusters of round pores (and cracks radiating from the pores) were found immediately beneath the molybdenum coating. These pores are believed to result from tellurium vaporization during the spray process where the molten molybdenum droplets (2623%C2%B0C) transferred their heat of solidification to the substrate at the moment of impact. Substrate cooling during the molybdenum deposition process was recommended to mitigate tellurium vaporization in future studies.

  9. Analysis of shielding charged particle beams by thin conductors

    Directory of Open Access Journals (Sweden)

    Robert Gluckstern

    2001-02-01

    Full Text Available We present an analysis of shielding of electromagnetic fields excited by beams of charged particles surrounded by thin conducting layers or metal stripes inside an external structure of finite length. The ability of shielding by a layer thinner than the skin depth is explained and expressions for the impedance are derived. A previous result showing preferential penetration through the shielding layer at the resonant frequencies of the surrounding structure is verified and extended to include finite resistivity of the outer structure. Integration over the spectrum of the beam bunch shows that penetration is (nearly independent of the quality factors of the resonances. The transition of these results to those for a geometry of infinite length requires numerical evaluation.

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

    Science.gov (United States)

    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.

  11. Interstitial rotating shield brachytherapy for prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Quentin E., E-mail: quentin-adams@uiowa.edu; Xu, Jinghzu; Breitbach, Elizabeth K.; Li, Xing; Rockey, William R.; Kim, Yusung; Wu, Xiaodong; Flynn, Ryan T. [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Enger, Shirin A. [Medical Physics Unit, McGill University, 1650 Cedar Ave, Montreal, Quebec H3G 1A4 (Canada)

    2014-05-15

    Purpose: To present a novel needle, catheter, and radiation source system for interstitial rotating shield brachytherapy (I-RSBT) of the prostate. I-RSBT is a promising technique for reducing urethra, rectum, and bladder dose relative to conventional interstitial high-dose-rate brachytherapy (HDR-BT). Methods: A wire-mounted 62 GBq{sup 153}Gd source is proposed with an encapsulated diameter of 0.59 mm, active diameter of 0.44 mm, and active length of 10 mm. A concept model I-RSBT needle/catheter pair was constructed using concentric 50 and 75 μm thick nickel-titanium alloy (nitinol) tubes. The needle is 16-gauge (1.651 mm) in outer diameter and the catheter contains a 535 μm thick platinum shield. I-RSBT and conventional HDR-BT treatment plans for a prostate cancer patient were generated based on Monte Carlo dose calculations. In order to minimize urethral dose, urethral dose gradient volumes within 0–5 mm of the urethra surface were allowed to receive doses less than the prescribed dose of 100%. Results: The platinum shield reduced the dose rate on the shielded side of the source at 1 cm off-axis to 6.4% of the dose rate on the unshielded side. For the case considered, for the same minimum dose to the hottest 98% of the clinical target volume (D{sub 98%}), I-RSBT reduced urethral D{sub 0.1cc} below that of conventional HDR-BT by 29%, 33%, 38%, and 44% for urethral dose gradient volumes within 0, 1, 3, and 5 mm of the urethra surface, respectively. Percentages are expressed relative to the prescription dose of 100%. For the case considered, for the same urethral dose gradient volumes, rectum D{sub 1cc} was reduced by 7%, 6%, 6%, and 6%, respectively, and bladder D{sub 1cc} was reduced by 4%, 5%, 5%, and 6%, respectively. Treatment time to deliver 20 Gy with I-RSBT was 154 min with ten 62 GBq {sup 153}Gd sources. Conclusions: For the case considered, the proposed{sup 153}Gd-based I-RSBT system has the potential to lower the urethral dose relative to HDR-BT by 29

  12. An evaluation of the shielding effectiveness of lead aprons used in clinics for protection against ionising radiation from novel radioisotopes.

    Science.gov (United States)

    Deb, Pradip; Jamison, Robert; Mong, Lisa; U, Paul

    2015-07-01

    The purpose of this study is to evaluate the effectiveness of personal radiation shields currently worn in hospital and other diagnostic environments. This study was performed with four different radioisotopes; (18)F, (99m)Tc, (124)I and (131)I. (18)F results showed a decrease in dose with 0.5-mm Pb shielding but the reduction provided does not warrant its use clinically. (124)I testing demonstrated that dose enhancement can occur in greater shield thicknesses. PET isotope (124)I can be adequately shielded using 0.25-mm Pb equivalent aprons but any higher thickness increase the wearer's dose. As a result more shielding does not always equal more protection. The (131)I test showed that no dose reduction occurred, even when tested with up to 1.25-mm Pb equivalent shielding. Novel radioisotopes being used in the laboratory and clinic should be individually tested as each requires specific shielding testing.

  13. Innovative neutron shielding materials composed of natural rubber-styrene butadiene rubber blends, boron oxide and iron(III) oxide

    Science.gov (United States)

    Jumpee, C.; Wongsawaeng, D.

    2015-05-01

    Optimized flexible and lightweight neutron shielding materials were designed using the Monte Carlo N-Particle (MCNP) code. Thicknesses of 10 mm and 100 mm were tested for neutron shielding performances. Simulation results indicated that the 10 mm shielding material of natural rubber (NR) and styrene butadiene rubber (SBR) blend (1:1) with 60 part per hundred rubber (phr) boron oxide (B2O3) and 100 mm shielding material with four alternating layers of NR with 100 phr iron (III) oxide (Fe2O3) and of NR and SBR blend (1:1) with 10 phr B2O3 were most suitable for thermal neutron shielding and all-energy neutron shielding, respectively. Experimental results verified the shielding efficiency of these optimal designs and ease of fabrication.

  14. One-step synthesis of bismuth molybdate catalysts via flame spray pyrolysis for the selective oxidation of propylene to acrolein

    DEFF Research Database (Denmark)

    Schuh, K.; Kleist, W.; Høj, Martin

    2014-01-01

    Flame spray pyrolysis (FSP) of Bi(III)-and Mo(VI)-2-ethylhexanoate dissolved in xylene resulted in various nanocrystalline bismuth molybdate phases depending on the Bi/Mo ratio. Besides alpha-Bi2Mo3O12 and gamma-Bi2MoO6, FSP gave direct access to the metastable beta-Bi2Mo2O9 phase with high surfa...... to acrolein at temperatures relevant for industrial applications (360 degrees C)....

  15. Superconducting and hybrid systems for magnetic field shielding

    Science.gov (United States)

    Gozzelino, L.; Gerbaldo, R.; Ghigo, G.; Laviano, F.; Truccato, M.; Agostino, A.

    2016-03-01

    In this paper we investigate and compare the shielding properties of superconducting and hybrid superconducting/ferromagnetic systems, consisting of cylindrical cups with an aspect ratio of height/radius close to unity. First, we reproduced, by finite-element calculations, the induction magnetic field values measured along the symmetry axis in a superconducting (MgB2) and in a hybrid configuration (MgB2/Fe) as a function of the applied magnetic field and of the position. The calculations are carried out using the vector potential formalism, taking into account simultaneously the non-linear properties of both the superconducting and the ferromagnetic material. On the basis of the good agreement between the experimental and the computed data we apply the same model to study the influence of the geometric parameters of the ferromagnetic cup as well as of the thickness of the lateral gap between the two cups on the shielding properties of the superconducting cup. The results show that in the considered non-ideal geometry, where the edge effect in the flux penetration cannot be disregarded, the superconducting shield is always the most efficient solution at low magnetic fields. However, a partial recovery of the shielding capability of the hybrid configuration occurs if a mismatch in the open edges of the two cups is considered. In contrast, at high magnetic fields the hybrid configurations are always the most effective. In particular, the highest shielding factor was found for solutions with the ferromagnetic cup protruding over the superconducting one.

  16. Empennage Noise Shielding Benefits for an Open Rotor Transport

    Science.gov (United States)

    Berton, Jeffrey J.

    2012-01-01

    NASA sets aggressive, strategic, civil aircraft performance and environmental goals and develops ambitious technology roadmaps to guide its research efforts. NASA has adopted a phased approach for community noise reduction of civil aircraft. While the goal of the near-term first phase focuses primarily on source noise reduction, the goal of the second phase relies heavily on presumed architecture changes of future aircraft. The departure from conventional airplane configurations to designs that incorporate some type of propulsion noise shielding is anticipated to provide an additional 10 cumulative EPNdB of noise reduction. One candidate propulsion system for these advanced aircraft is the open rotor engine. In some planned applications, twin open rotor propulsors are located on the aft fuselage, with the vehicle s empennage shielding some of their acoustic signature from observers on the ground. This study focuses on predicting the noise certification benefits of a notional open rotor aircraft with tail structures shielding a portion of the rotor noise. The measured noise of an open rotor test article--collected with and without an acoustic barrier wall--is the basis of the prediction. The results are used to help validate NASA s reliance on acoustic shielding to achieve the second phase of its community noise reduction goals. The noise measurements are also compared to a popular empirical diffraction correlation often used at NASA to predict acoustic shielding.

  17. Magnetic Shielding Studies of the RICH Photon Detectors

    CERN Document Server

    Patel, M; Gys, Thierry

    2006-01-01

    The Hybrid Photon Detectors (HPDs) adopted for LHCb's RICH detectors are required to operate in the fringe field of the 4Tm LHCb dipole magnet. In fields in excess of 15G, photoelectrons are lost from the active area of an HPD. Shielding the HPDs from the fringe field is therefore essential for the efficient operation of the RICH detectors. A primary magnetic shield has been designed that reduces the field at the photon detectors to <20G. This field is to be further reduced by a set of individual secondary magnetic shields around each HPD. This note describes the technique used to calculate the residual field inside these secondary shields. The size of the problem, together with the disparity in the geometric scales involved, make the calculations intractable using a finite element model of the entire magnetic environment. As a result, a sub-modelling method has been used together with a rectangular approximation to the circular cross-section shields. The model indicates that with a 89.5mm HPD pitch, 0.9mm...

  18. Jet Noise Shielding Provided by a Hybrid Wing Body Aircraft

    Science.gov (United States)

    Doty, Michael J.; Brooks, Thomas F.; Burley, Casey L.; Bahr, Christopher J.; Pope, Dennis S.

    2014-01-01

    One approach toward achieving NASA's aggressive N+2 noise goal of 42 EPNdB cumulative margin below Stage 4 is through the use of novel vehicle configurations like the Hybrid Wing Body (HWB). Jet noise measurements from an HWB acoustic test in NASA Langley's 14- by 22-Foot Subsonic Tunnel are described. Two dual-stream, heated Compact Jet Engine Simulator (CJES) units are mounted underneath the inverted HWB model on a traversable support to permit measurement of varying levels of shielding provided by the fuselage. Both an axisymmetric and low noise chevron nozzle set are investigated in the context of shielding. The unshielded chevron nozzle set shows 1 to 2 dB of source noise reduction (relative to the unshielded axisymmetric nozzle set) with some penalties at higher frequencies. Shielding of the axisymmetric nozzles shows up to 6.5 dB of reduction at high frequency. The combination of shielding and low noise chevrons shows benefits beyond the expected additive benefits of the two, up to 10 dB, due to the effective migration of the jet source peak noise location upstream for increased shielding effectiveness. Jet noise source maps from phased array results processed with the Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS) algorithm reinforce these observations.

  19. Determining the background levels of bismuth in tissues of wild game birds: a first step in addressing the environmental consequences of using bismuth shotshells

    Energy Technology Data Exchange (ETDEWEB)

    Jayasinghe, R.; Tsuji, L.J.S.; Gough, W.A.; Karagatzides, J.D.; Perera, D.; Nieboer, E

    2004-11-01

    Bismuth shotshells have been approved as a 'nontoxic' alternative to lead in North America. Approval was based on a limited number of studies; even background levels of bismuth in wildfowl were unknown. We report on the concentration of bismuth (and lead) in muscle and liver tissues of wildfowl (Anas platyrhynchos, Anas acuta, Anas crecca, Branta canadensis, Chen caerulescens) harvested with lead shotshell. Average liver-bismuth levels detected in the present study (e.g., teal, 0.05 {mu}g/g dw; mallard, 0.09 {mu}g/g dw) suggest analytical error in other studies examining the effects of bismuth in birds. Significant positive relationships between bismuth- and lead-tissue levels for muscle when all species were combined (and for B. canadensis and C. caerulescens separately) can be explained by noting that bismuth is a contaminant of lead. Thus, more research is recommended to confirm the appropriateness of bismuth as a 'nontoxic' shot alternative.

  20. Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Biasotto, G. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil); Simoes, A.Z., E-mail: alezipo@yahoo.com [Universidade Estadual Paulista-Unesp, Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333, Bairro Pedregulho, CEP 12516-410, Guaratingueta, SP (Brazil); Foschini, C.R.; Zaghete, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer BiFeO{sub 3} (BFO) nanoparticles were grown by hydrothermal microwave method (HTMW). Black-Right-Pointing-Pointer The soaking time is effective in improving phase formation. Black-Right-Pointing-Pointer Rietveld refinement reveals an orthorhombic structure. Black-Right-Pointing-Pointer The observed magnetism of the BFO crystallites is a consequence of particle size. Black-Right-Pointing-Pointer The HTMW is a genuine technique for low temperatures and short times of synthesis. -- Abstract: Hydrothermal microwave method (HTMW) was used to synthesize crystalline bismuth ferrite (BiFeO{sub 3}) nanoparticles (BFO) in the temperature of 180 Degree-Sign C with times ranging from 5 min to 1 h. BFO nanoparticles were characterized by means of X-ray analyses, FT-IR, Raman spectroscopy, TG-DTA and FE-SEM. X-ray diffraction results indicated that longer soaking time was benefit to refraining the formation of any impurity phases and growing BFO crystallites into almost single-phase perovskites. Typical FT-IR spectra for BFO nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH{sup -} groups, commonly found in materials obtained by HTMW process. Compared with the conventional solid-state reaction process, submicron BFO crystallites with better homogeneity could be produced at the temperature as low as 180 Degree-Sign C. These results show that the HTMW synthesis route is rapid, cost effective, and could be used as an alternative to obtain BFO nanoparticles in the temperature of 180 Degree-Sign C for 1 h.

  1. Picosecond 1.3{-}\\unicode{956} {\\text{m}} bismuth fibre laser mode-locked by a nonlinear loop mirror

    Science.gov (United States)

    Khegai, A. M.; Afanas'ev, F. V.; Riumkin, K. E.; Firstov, S. V.; Khopin, V. F.; Myasnikov, D. V.; Mel'kumov, M. A.; Dianov, E. M.

    2016-12-01

    The influence of the concentration of bismuth active centres (BACs) in phosphosilicate fibres on their optical parameters, including gain coefficient and non-saturable losses, has been studied. A range of BAC concentrations optimal for designing ultrashort-pulse (USP) lasers was chosen based on the obtained results. The optimised fibre was used to fabricate an all-fibre 1.3-\\unicode{956}{\\text{m}} USP laser mode-locked by a nonlinear loop mirror, which emits 11.3-{\\text{ps}} pulses with an energy of 1.65 {\\text{nJ}} and a repetition rate of 3.6 {\\text{MHz}}. A bismuth fibre amplifier made it possible to increase the pulse energy to 8.3 {\\text{nJ}}. After compression in a diffraction grating compressor, the pulse duration decreased to 530 {\\text{fs}}.

  2. Determination of trace amounts of Ga(III) by adsorptive stripping voltammetry with in situ plated bismuth film electrode.

    Science.gov (United States)

    Grabarczyk, Malgorzata; Wasąg, Joanna

    2015-11-01

    The determination of trace gallium using adsorptive stripping voltammetry at an in situ plated bismuth film electrode was described. The method was based on simultaneous film formation and the Ga(III)-cupferron complex preconcentration at -0.65 V and its cathodic stripping during the potential scan. The effect of Bi(III) and cupferron concentration, the influence of deposition potential and time, and the scan rate on the determination of Ga(III) were studied. A linear response in the concentration range of 3×10(-10) to 3×10(-7) mol L(-1) (r=0.998) was obtained with detection limit of 1.05×10(-10) mol L(-1) using accumulation time of 180 s. Finally, the bismuth film electrode was successfully applied for the determination of Ga(III) in certified reference material seawater NASS-5 with satisfactory results.

  3. Operating Practice for Recovering Bismuth from Bismuth Dross%从铋渣中回收铋的生产实践

    Institute of Scientific and Technical Information of China (English)

    刘金铭

    2015-01-01

    阐述了从处理铅阳极泥时产生的铋渣中回收铋的生产实践,采用湿法浸出→氯氧铋→热浓碱转型→氧化铋→还原熔炼→火法精炼的生产工艺,为铋渣的处理提供了新的途径。%This paper expounds operating practice for recovering bismuth from bismuth dross that were outputed during dealing with the lead anode mud in pyrometallurgical process,which uesd production process of leaching—bismuth oxychloride—transformation—bismuth oxide—reduction smelting—pyrometallurgical refining.The operating practice provided a new technology to process the bismuth dross.

  4. Diffusion-controlled intergranular penetration and embrittlement of copper by liquid bismuth between 300 and 600 Celsius degrees; Penetration intergranulaire fragilisante du cuivre par le bismuth liquide: identification de la cinetique et du mecanisme de type diffusionnel entre 300 et 600 deg

    Energy Technology Data Exchange (ETDEWEB)

    Laporte, V

    2005-02-15

    Hybrid reactors are a new concept for energy production and nuclear waste treatment. Among other requirements, structural materials have to withstand liquid metal embrittlement. This thesis aimed therefore to identify the controlling mechanism for the intergranular embrittlement of copper in contact with liquid bismuth. Scanning electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy have been used to analyze fracture surfaces of both copper polycrystals and a copper bicrystal (symmetric tilt boundary 50 degrees <100>). These analyses reveal both parabolic intergranular penetration kinetics and a maximal intergranular bismuth concentration that is less than two monolayers equivalent. These two results allow us to identify grain boundary diffusion as the controlling mechanism for the intergranular penetration of copper by liquid bismuth between 300 and 600 Celsius degrees, showing the absence of perfect grain boundary wetting. (author)

  5. Bismuth subsalicylate nanoparticles with anaerobic antibacterial activity for dental applications

    Science.gov (United States)

    Vega-Jiménez, A. L.; Almaguer-Flores, A.; Flores-Castañeda, M.; Camps, E.; Uribe-Ramírez, M.; Aztatzi-Aguilar, O. G.; De Vizcaya-Ruiz, A.

    2017-10-01

    In recent years, nanomaterials have been used in the medical-dental field as new alternative antimicrobial agents. Bismuth subsalicylate (BSS) has been used as an antimicrobial agent, but the effect of BSS in the form of nanoparticles (BSS-nano) as a potential antimicrobial agent has not been tested, in specific against bacteria responsible for periodontal disease. The aim of this study was to evaluate the antibacterial effect of BSS-nano against oral anaerobic bacteria and to assess the safety of BSS-nano by evaluating their cytotoxicity in human gingival fibroblast (HGF-1) cells. BSS-nano were synthesized by laser ablation and were previously physico-chemically characterized using in vitro assays. The antibacterial activity was measured using the tetrazolium-based XTT assay, and cytotoxicity was determined using lactate dehydrogenase (LDH) and MTS assays in HGF-1 cells. Transmission electron microscopy of HGF-1 exposed to BSS-nano was also performed. BSS-nano was shown to have a primary size of 4–22 nm and a polygonal shape. Among the tested bacterial strains, those with a greater sensitivity to BSS-nano (highest concentration of 21.7 μg ml‑1) were A. actinomycetemcomitans, C. gingivalis, and P. gingivalis. BSS-nano at a concentration of 60 μg ml‑1 showed low cytotoxicity (6%) in HFG-1 cells and was mainly localized intracellularly in acidic vesicles. Our results indicate that the concentration of BSS-nano used as an effective antibacterial agent does not induce cytotoxicity in mammalian cells; thus, BSS-nano can be applied as an antibacterial agent in dental materials or antiseptic solutions.

  6. Formic acid oxidation at platinum-bismuth catalysts

    Directory of Open Access Journals (Sweden)

    Popović Ksenija Đ.

    2015-01-01

    Full Text Available The field of heterogeneous catalysis, specifically catalysis on bimetallic surfaces, has seen many advances over the past few decades. Bimetallic catalysts, which often show electronic and chemical properties that are distinct from those of their parent metals, offer the opportunity to obtain new catalysts with enhanced selectivity, activity, and stability. The oxidation of formic acid is of permanent interest as a model reaction for the mechanistic understanding of the electrooxidation of small organic molecules and because of its technical relevance for fuel cell applications. Platinum is one of the most commonly used catalysts for this reaction, despite the fact that it shows a few significant disadvantages: high cost and extreme susceptibility to poisoning by CO. To solve this problem, several approaches have been used, but generally, they all consist in the modification of platinum with a second element. Especially, bismuth has received significant attention as Pt modifier. According to the results presented in this survey dealing with the effects influencing the formic acid oxidation it was found that two types of Pt-Bi bimetallic catalysts (bulk and low loading deposits on GC showed superior catalytic activity in terms of the lower onset potential and oxidation current density, as well as exceptional stability compared to Pt. The findings in this report are important for the understanding of mechanism of formic acid electrooxidation on a bulk alloy and decorated surface, for the development of advanced anode catalysts for direct formic acid fuel cells, as well as for the synthesis of novel low-loading bimetallic catalysts. The use of bimetallic compounds as the anode catalysts is an effective solution to overcoming the problems of the formic acid oxidation current stability for long term applications. In the future, the tolerance of both CO poisoning and electrochemical leaching should be considered as the key factors in the development

  7. Evaluation Of Shielding Efficacy Of A Ferrite Containing Ceramic Material

    Energy Technology Data Exchange (ETDEWEB)

    Verst, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-12

    The shielding evaluation of the ferrite based Mitsuishi ceramic material has produced for several radiation sources and possible shielding sizes comparative dose attenuation measurements and simulated projections. High resolution gamma spectroscopy provided uncollided and scattered photon spectra at three energies, confirming theoretical estimates of the ceramic’s mass attenuation coefficient, μ/ρ. High level irradiation experiments were performed using Co-60, Cs-137, and Cf-252 sources to measure penetrating dose rates through steel, lead, concrete, and the provided ceramic slabs. The results were used to validate the radiation transport code MCNP6 which was then used to generate dose rate attenuation curves as a function of shielding material, thickness, and mass for photons and neutrons ranging in energy from 200 keV to 2 MeV.

  8. Electromagnetic shielding of thermal protection system for hypersonic vehicles

    Science.gov (United States)

    Albano, M.; Micheli, D.; Gradoni, G.; Morles, R. B.; Marchetti, M.; Moglie, F.; Mariani Primiani, V.

    2013-06-01

    The numerical simulation and the measurement of electromagnetic shielding at microwave frequencies of thermal protection system for hypersonic vehicles is presented using nested reverberation chamber. An example of a possible thermal protection system for a re-entry vehicle is presented. This system based on carbon material is electromagnetically characterized. The characterization takes into account not only the materials but also the final assembly configuration of the thermal protection system. The frequency range is 2-8 GHz. The results of measurements and simulations show that the microwave shielding effectiveness of carbon materials is above 60 dB for a single tile and that the tile inter-distance is able to downgrade the shielding effectiveness on the average to about 40 dB.

  9. STUDY OF WING SHIELDING EFFECT OF PROPELLER AIRCRAFT

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The calculation of wing shielding effect starts from solving Ffowcs Williams and Hawkings equation without quadrupole source in time domain. The sound scattering of the wing and fuselage which are surrounded by a multi-propeller sound field is modeled as a second sound source. A program is developed to calculate the acoustical effects of the rigid fuselage as well as wings with arbitrary shape in motion at low Mach number. As an example, the numerical calculation of the wing shielding of Y12 aircraft with an approximate shape is presented. The result manifests clearly the shielding effect of the wing on the fuselage and the approach is more efficient than that published before.

  10. Radiation Shielding Properties of Some Marbles in Turkey

    Science.gov (United States)

    Günoǧlu, K.; Akkurt, I.

    2011-12-01

    Especially after development of technology, radiation started to be used in a large fields such as medicine, industry and energy. Using radiation in those fields bring hazordous effect of radition into humancell. Thus radiation protection becomes important in physics. Although there are three ways for radiation protection, shielding of the radiation is the most commonly used method. Natural Stones such as marble is used as construction material especially in critical building and thus its radiation shielding capability should be determined. In this study, gamma ray shielding properties of some different types of marble mined in Turkey, have been measured using a NaI(Tl) scintillator detector. The measured results were also compared with the theoretical calculations XCOM.

  11. Characteristics of Electromagnetic Coupling with A Wire through Shielding Enclosure

    Directory of Open Access Journals (Sweden)

    Yanpeng Sun

    2013-09-01

    Full Text Available The paper presents a numerical method based on Finite Difference Time Domain (FDTD in both frequency and time domain for modeling the coupling of an incident electromagnetic pulse(EMP with a conducting wire through a metallic shielding enclosure with a small aperture. Simulation and analysis are done by radius, length, and number of the wires, the incidence angle of EMP and the polaration angle of electric field in consideration. The simulation result shows that interference of the electromagnetic coupling into the shielding enclosure can be affected in different degrees by above factors. At low frequency, the larger the leakage length, the radius or the number of the wire penetrated into the cavity, the more interference is coupled into the shielding cavity from electromagnetic field. Also, the smaller the incident direction angle of propagation of the electromagnetic pulse or the polarization direction angle of the incident electric field, the more easily the electromagnetic interference is coupled into the cavity.

  12. Investigating Radiation Shielding Properties of Different Mineral Origin Heavyweight Concretes

    Science.gov (United States)

    Basyigit, Celalettin; Uysal, Volkan; Kilinçarslan, Şemsettin; Mavi, Betül; Günoǧlu, Kadir; Akkurt, Iskender; Akkaş, Ayşe

    2011-12-01

    The radiation although has hazardous effects for human health, developing technologies bring lots of usage fields to radiation like in medicine and nuclear power station buildings. In this case protecting from undesirable radiation is a necessity for human health. Heavyweight concrete is one of the most important materials used in where radiation should be shielded, like those areas. In this study, used heavyweight aggregates of different mineral origin (Limonite, Siderite), in order to prepare different series in concrete mixtures and investigated radiation shielding properties. The experimental results on measuring the radiation shielding, the heavyweight concrete prepared with heavyweight aggregates of different mineral origin show that, are useful radiation absorbents when they used in concrete mixtures.

  13. Simplified shielding calculation system for high-intensity proton accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Masumura, Tomomi; Nakashima, Hiroshi; Nakane, Yoshihiro; Sasamoto, Nobuo [Center for Neutron Science, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    2000-06-01

    A simplified shielding calculation system is developed for applying conceptual shielding design of facilities in the joint project for high-intensity proton accelerators. The system is composed of neutron transmission calculation part for bulk shielding using simplified formulas: Moyer model and Tesch's formula, and neutron skyshine calculation part using an empirical formula: Stapleton's formula. The system is made with the Microsoft Excel software for user's convenience. This report provides a manual for the system as well as calculation conditions used in the calculation such as Moyer model's parameters. In this report preliminary results based on data at December 8, 1999, are also shown as an example. (author)

  14. Rapid Analysis of Mass Distribution of Radiation Shielding

    Science.gov (United States)

    Zapp, Edward

    2007-01-01

    Radiation Shielding Evaluation Toolset (RADSET) is a computer program that rapidly calculates the spatial distribution of mass of an arbitrary structure for use in ray-tracing analysis of the radiation-shielding properties of the structure. RADSET was written to be used in conjunction with unmodified commercial computer-aided design (CAD) software that provides access to data on the structure and generates selected three-dimensional-appearing views of the structure. RADSET obtains raw geometric, material, and mass data on the structure from the CAD software. From these data, RADSET calculates the distribution(s) of the masses of specific materials about any user-specified point(s). The results of these mass-distribution calculations are imported back into the CAD computing environment, wherein the radiation-shielding calculations are performed.

  15. Effect of compositional variation in plutonium on process shielding design

    Energy Technology Data Exchange (ETDEWEB)

    Brown, T.H.

    1997-11-01

    Radiation dose rate from plutonium with high {sup 239}Pu content varies with initial nuclidic content, radioactive decay time, and impurity elemental content. The two idealized states of old plutonium and clean plutonium, whose initial compositions are given, provide approximate upper and lower bounds on dose rate variation. Whole-body dose rates were calculated for the two composition states, using unshielded and shielded plutonium spheres of varying density. The dose rates from these variable density spheres are similar to those from expanded plutonium configurations encountered during processing. The dose location of 40 cm from the sphere center is representative of operator standoff for direct handling of plutonium inside a glove box. The results have shielding implications for glove boxes with only structurally inherent shielding, especially for processing of old plutonium in an expanded configuration. Further reduction in total dose rate by using lead to reduce photon dose rate is shown for two density cases representing compact and expanded plutonium configurations.

  16. Optimum Location of Thermal Radiation Shield in Superconducting Rotating Machines

    Science.gov (United States)

    Saikiran, P. A.; Rao, V. V.

    2017-02-01

    Superconducting rotating machines have rotor maintained at low temperatures, below the critical temperature of the superconductor. This establishes large temperature difference between the cold rotor and surroundings, resulting in large heat leak into rotor through conduction, convection and radiation. Minimizing this heat leak is essential to reduce the power expense of cryogenic cooling system. A radiation shield is anchored at a suitable location on torque tube to minimize the radiation heat leak into the cold rotor. This paper presents a methodology to determine the optimum location of this anchor-point of radiation shield for a given geometry, which minimizes the total heat leak into cold rotor. The location of radiation shield is found to be depending on emissivity of cold rotor.

  17. Greener Friedel-Crafts Acylation using Microwave-enhanced reactivity of Bismuth Triflate in the Friedel-Crafts Benzoylation of Aromatic Compounds with Benzoic Anhydride

    DEFF Research Database (Denmark)

    Tran, Phuong Hoang; Nguyen, hai Truong; Hansen, Poul Erik

    2017-01-01

    An efficient and facile bismuth trifluoromethanesulfonate-catalyzed benzoylation of aromatic compounds using benzoic anhydride under solvent-free microwave irradiation has been developed. The microwave-assisted Friedel-Crafts benzoylation results in good yields within short reaction times. Bismut...

  18. Optimization of Shielded Scintillator for Neutron Detection

    Science.gov (United States)

    Belancourt, Patrick; Morrison, John; Akli, Kramer; Freeman, Richard; High Energy Density Physics Team

    2011-10-01

    The High Energy Density Physics group is interested in the basic science of creating a neutron and gamma ray source. The neutrons and gamma rays are produced by accelerating ions via a laser into a target and creating fusion neutrons and gamma rays. A scintillator and photomultiplier tube will be used to detect these neutrons. Neutrons and photons produce ionizing radiation in the scintillator which then activates metastable states. These metastable states have both short and long decay rates. The initial photon count is orders of magnitude higher than the neutron count and poses problems for accurately detecting the neutrons due to the long decay state that is activated by the photons. The effects of adding lead shielding on the temporal response and signal level of the neutron detector will be studied in an effort to minimize the photon count without significant reduction to the temporal resolution of the detector. MCNP5 will be used to find the temporal response and energy deposition into the scintillator by adding lead shielding. Results from the simulations will be shown. Optimization of our scintillator neutron detection system is needed to resolve the neutron energies and neutron count of a novel neutron and gamma ray source.

  19. Large scale mechanical metamaterials as seismic shields

    Science.gov (United States)

    Miniaci, Marco; Krushynska, Anastasiia; Bosia, Federico; Pugno, Nicola M.

    2016-08-01

    Earthquakes represent one of the most catastrophic natural events affecting mankind. At present, a universally accepted risk mitigation strategy for seismic events remains to be proposed. Most approaches are based on vibration isolation of structures rather than on the remote shielding of incoming waves. In this work, we propose a novel approach to the problem and discuss the feasibility of a passive isolation strategy for seismic waves based on large-scale mechanical metamaterials, including for the first time numerical analysis of both surface and guided waves, soil dissipation effects, and adopting a full 3D simulations. The study focuses on realistic structures that can be effective in frequency ranges of interest for seismic waves, and optimal design criteria are provided, exploring different metamaterial configurations, combining phononic crystals and locally resonant structures and different ranges of mechanical properties. Dispersion analysis and full-scale 3D transient wave transmission simulations are carried out on finite size systems to assess the seismic wave amplitude attenuation in realistic conditions. Results reveal that both surface and bulk seismic waves can be considerably attenuated, making this strategy viable for the protection of civil structures against seismic risk. The proposed remote shielding approach could open up new perspectives in the field of seismology and in related areas of low-frequency vibration damping or blast protection.

  20. Enhanced radiation shielding with galena concrete

    Directory of Open Access Journals (Sweden)

    Hadad Kamal

    2015-01-01

    Full Text Available A new concrete, containing galena mineral, with enhanced shielding properties for gamma sources is developed. To achieve optimized shielding properties, ten types of galena concrete containing different mixing ratios and a reference normal concrete of 2300 kg/m3 density are studied experimentally and numerically using Monte Carlo and XCOM codes. For building galena concrete, in addition to the main composition, micro-silica and water, galena mineral (containing lead were used. The built samples have high density of 4470 kg/m3 to 5623 kg/m3 and compressive strength of 628 kg/m2 to 685 kg/m2. The half and tenth value layers (half value layer and tenth value layers for the galena concrete, when irradiated with 137Cs gamma source, were found to be 1.45 cm and 4.94 cm, respectively. When irradiated with 60Co gamma source, half value layer was measured to be 2.42 cm. The computation modeling by FLUKA and XCOM shows a good agreement between experimental and computational results.

  1. A superconducting shield to protect astronauts

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    The CERN Superconductors team in the Technology department is involved in the European Space Radiation Superconducting Shield (SR2S) project, which aims to demonstrate the feasibility of using superconducting magnetic shielding technology to protect astronauts from cosmic radiation in the space environment. The material that will be used in the superconductor coils on which the project is working is magnesium diboride (MgB2), the same type of conductor developed in the form of wire for CERN for the LHC High Luminosity Cold Powering project.   Image: K. Anthony/CERN. Back in April 2014, the CERN Superconductors team announced a world-record current in an electrical transmission line using cables made of the MgB2 superconductor. This result proved that the technology could be used in the form of wire and could be a viable solution for both electrical transmission for accelerator technology and long-distance power transportation. Now, the MgB2 superconductor has found another application: it wi...

  2. Discussion on variance reduction technique for shielding

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Fujio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    As the task of the engineering design activity of the international thermonuclear fusion experimental reactor (ITER), on 316 type stainless steel (SS316) and the compound system of SS316 and water, the shielding experiment using the D-T neutron source of FNS in Japan Atomic Energy Research Institute has been carried out. However, in these analyses, enormous working time and computing time were required for determining the Weight Window parameter. Limitation or complication was felt when the variance reduction by Weight Window method of MCNP code was carried out. For the purpose of avoiding this difficulty, investigation was performed on the effectiveness of the variance reduction by cell importance method. The conditions of calculation in all cases are shown. As the results, the distribution of fractional standard deviation (FSD) related to neutrons and gamma-ray flux in the direction of shield depth is reported. There is the optimal importance change, and when importance was increased at the same rate as that of the attenuation of neutron or gamma-ray flux, the optimal variance reduction can be done. (K.I.)

  3. Earth pressure balance control for EPB shield

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This paper mainly deals with the critical technology of earth pressure balance (EPB) control in shield tunneling. On the assumption that the conditioned soil in the working chamber of the shield is plasticized, a theoretical principle for EPB control is proposed. Dynamic equilibrium of intake volume and discharge volume generated by thrust and discharge is modeled theoretically to simulate the earth pressure variation during excavating. The thrust system and the screw conveyor system for earth pressure control are developed based on the electro-hydraulic technique. The control models of the thrust speed regulation of the cylinders and the rotating speed adjustment of the screw conveyor are also presented. Simulation for earth pressure control is conducted with software AMESim and MATLAB/Simulink to verify the models. Experiments are carried out with intake control in clay soil and discharge control in sandy gravel section, respectively. The experimental results show that the earth pressure variations in the working chamber can be kept at the expected value with a practically acceptable precision by means of real-time tuning the thrust speed or the revolving speed of discharge system.

  4. Dique seco, en South Shields

    Directory of Open Access Journals (Sweden)

    Frank Stott, Peter

    1958-10-01

    Full Text Available La conocida empresa Brigham & Cowan Ltd, de South Shields (Inglaterra, acaba de construir un dique de carena en la desembocadura del río Tyne, destinado a la reparación de tanques y cargas de gran tonelaje y de relativamente poco calado. El vaso tiene 217 m de longitud, 29 de anchura mínima en la entrada, 6,40 de a l tura de agua sobre el umbral de entrada y una compuerta metálica rebatible hacia adelante. En este trabajo se describen las partes que mejor caracterizan esta importante obra.

  5. Dynamic rotating-shield brachytherapy.

    Science.gov (United States)

    Liu, Yunlong; Flynn, Ryan T; Kim, Yusung; Yang, Wenjun; Wu, Xiaodong

    2013-12-01

    To present dynamic rotating shield brachytherapy (D-RSBT), a novel form of high-dose-rate brachytherapy (HDR-BT) with electronic brachytherapy source, where the radiation shield is capable of changing emission angles during the radiation delivery process. A D-RSBT system uses two layers of independently rotating tungsten alloy shields, each with a 180° azimuthal emission angle. The D-RSBT planning is separated into two stages: anchor plan optimization and optimal sequencing. In the anchor plan optimization, anchor plans are generated by maximizing the D90 for the high-risk clinical-tumor-volume (HR-CTV) assuming a fixed azimuthal emission angle of 11.25°. In the optimal sequencing, treatment plans that most closely approximate the anchor plans under the delivery-time constraint will be efficiently computed. Treatment plans for five cervical cancer patients were generated for D-RSBT, single-shield RSBT (S-RSBT), and (192)Ir-based intracavitary brachytherapy with supplementary interstitial brachytherapy (IS + ICBT) assuming five treatment fractions. External beam radiotherapy doses of 45 Gy in 25 fractions of 1.8 Gy each were accounted for. The high-risk clinical target volume (HR-CTV) doses were escalated such that the D2cc of the rectum, sigmoid colon, or bladder reached its tolerance equivalent dose in 2 Gy fractions (EQD2 with α∕β = 3 Gy) of 75 Gy, 75 Gy, or 90 Gy, respectively. For the patients considered, IS + ICBT had an average total dwell time of 5.7 minutes∕fraction (min∕fx) assuming a 10 Ci(192)Ir source, and the average HR-CTV D90 was 78.9 Gy. In order to match the HR-CTV D90 of IS + ICBT, D-RSBT required an average of 10.1 min∕fx more delivery time, and S-RSBT required 6.7 min∕fx more. If an additional 20 min∕fx of delivery time is allowed beyond that of the IS + ICBT case, D-RSBT and S-RSBT increased the HR-CTV D90 above IS + ICBT by an average of 16.3 Gy and 9.1 Gy, respectively. For cervical cancer patients, D-RSBT can boost HR-CTV D90

  6. One-step synthesis of in situ reduced metal Bi decorated bismuth molybdate hollow microspheres with enhancing photocatalytic activity

    Science.gov (United States)

    Jin, Meng; Lu, Shiyu; Ma, Li; Gan, Mengyu

    2017-02-01

    In this feature work, in situ metal Bi are successfully modified bismuth molybdate hollow spheres using an effective one-pot solvthermal reduction without any temple. In order to deeply understand the influence of reduction conditions on the texture, surface state, and photocatalytic performance of the resulting samples, a series of products were synthesized by tuning the temperatures. The similar morphology, surface area of photocatalysis (BMO-160 and BMO-170) were synthesized, only with the different composition. The detailed characterization and analysis distinctly suggested that increasing solvothermal reduction temperature led to Bi3+ was in situ reduced to elementary substance Bi0 by ethylene glycol gradually and dispersed very uniform in bismuth molybdate. Benefiting from the enhanced charge separation, transfer, and donor density resulting from the formation of Bi decorated bismuth molybdate where Bi as cocatalyst, the photocatalytic performance of the reductive Bi/Bi2-xMoOy hollow spheres (BMO-170) is higher than that of the untreated Bi2-xMoOy hollow spheres (BMO-160) for Rh6G degradation under visible light irradiation. Additionally, the reductive BMO-170 has a superior stability after five cycles.

  7. A Novel Technique for the Deposition of Bismuth Tungstate onto Titania Nanoparticulates for Enhancing the Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Marina Ratova

    2016-07-01

    Full Text Available A novel powder handling technique was used to allow the deposition of bismuth tungstate coatings onto commercial titanium dioxide photocatalytic nanoparticles. The coatings were deposited by reactive pulsed DC magnetron sputtering in an argon/oxygen atmosphere. The use of an oscillating bowl with rotary particle propagation, positioned beneath two closed-field planar magnetrons, provided uniform coverage of the titania particle surfaces. The bismuth/tungsten atomic ratio of the coatings was controlled by varying the power applied to each target. The resulting materials were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX, Brunauer–Emmett–Teller (BET surface area measurements, transmission electron microscopy (TEM, and UV-visible diffuse reflectance spectroscopy. Photocatalytic properties under visible light irradiation were assessed using an acetone degradation test. It was found that deposition of bismuth tungstate onto titania nanoparticles resulted in significant increases in visible light photocatalytic activity, compared to uncoated titania. Of the coatings studied, the highest photocatalytic activity was measured for the sample with a Bi/W atomic ratio of 2/1.

  8. Detailed mechanical design of the LIPAc beam dump radiological shielding

    OpenAIRE

    Nomen Escoda, Oriol; Mollá, Joaquin; Sanmartí, Manel; José I. Martínez; Arranz, Fernando; Iglesias, Daniel; Barrera, German; Brañas, Beatriz; Ogando, Francisco

    2013-01-01

    The LIPAc is a 9 MeV, D+ linear prototype accelerator for the validation of the IFMIF accelerator design. The high intensity, 125 mA CW beam is stopped in a copper cone involving a high production of neutrons and gamma radiation and activation of its surface. The beam stopper is surrounded by a shielding to attenuate the resulting radiation so that dose rate values comply with the limits at the different zones of the installation. The shielding includes for that purpose polyethylene rings...

  9. Ab initio calculation of the NMR shielding constants for histamine

    Science.gov (United States)

    Mazurek, A. P.; Dobrowolski, J. Cz.; Sadlej, J.

    1997-12-01

    The gage-independent atomic orbital (GIAO) approach is used within the coupled Hartree-Fock approximation to compute the 1H, 13C and 15N NMR shielding constants in two tautomeric forms of both the histamine molecule and its protonated form. An analysis of the results shows that the protonation on the end of the chain changes its nitrogen shielding constants of the pyridine and pyrrole type. These changes are much higher for the N(3)-H than for the N(1)-H tautomer.

  10. MCNPX vs. DORT for SNS shielding design studies.

    Science.gov (United States)

    Popova, Irina I

    2005-01-01

    Radiation transport occurs through the 18 m long access way adjacent to the Spallation Neutron Source accelerator tunnel and the 2.2 m thick massive shielding door which closes the access way. A variety of typical materials for accelerator shielding, such as concrete and steel, were used for construction of the door to study radiation penetration. A comparison was carried out using both Monte Carlo (code MCNPX) and discrete ordinates (code DORT) methods. The beam losses during the accelerator operation are the sources for the radiation calculations. Analyses show that the results from the two methods are in good agreement.

  11. Preliminary Design and Analysis of ITER In-Wall Shielding

    Institute of Scientific and Technical Information of China (English)

    LIU Changle; YU Jie; WU Songtao; CAI Yingxiang; PAN Wanjiang

    2007-01-01

    ITER in-wall shielding (IIS) is situated between the doubled shells of the ITER Vacuum Vessel (IVV). Its main functions are applied in shielding neutron, gamma-ray and toroidal field ripple reduction. The structure of IIS has been modelled according to the IVV design criteria which has been updated by the ITER team (IT). Static analysis and thermal expansion analysis were performed for the structure. Thermal-hydraulic analysis verified the heat removal capability and resulting temperature, pressure, and velocity changes in the coolant flow. Consequently, our design work is possibly suitable as a reference for IT's updated or final design in its next step.

  12. Recent Improvements in the SHIELD-HIT Code

    DEFF Research Database (Denmark)

    Hansen, David Christoffer; Lühr, Armin Christian; Herrmann, Rochus

    2012-01-01

    Purpose: The SHIELD-HIT Monte Carlo particle transport code has previously been used to study a wide range of problems for heavy-ion treatment and has been benchmarked extensively against other Monte Carlo codes and experimental data. Here, an improved version of SHIELD-HIT is developed...... of using accelerator control files as a basis for the primaries. Furthermore, the code has been parallelized and efficiency is improved. The physical description of inelastic ion collisions has been modified. Results: The simulation of an experimental depth-dose distribution including a ripple filter...

  13. Description of Transport Codes for Space Radiation Shielding

    Science.gov (United States)

    Kim, Myung-Hee Y.; Wilson, John W.; Cucinotta, Francis A.

    2011-01-01

    This slide presentation describes transport codes and their use for studying and designing space radiation shielding. When combined with risk projection models radiation transport codes serve as the main tool for study radiation and designing shielding. There are three criteria for assessing the accuracy of transport codes: (1) Ground-based studies with defined beams and material layouts, (2) Inter-comparison of transport code results for matched boundary conditions and (3) Comparisons to flight measurements. These three criteria have a very high degree with NASA's HZETRN/QMSFRG.

  14. Magnetic resonance imaging receiver coil decoupling using circumferential shielding structures.

    Science.gov (United States)

    Yeh, Jhy-Neng Tasso; Fa-Hsuan Lin

    2016-08-01

    We propose a flexible phased-array design using circular coils with circumferential shielding structure to achieve robust decoupling between coil elements when the array is either bended or on a flat plane. Two types of circumferential shielding were tested through numerical simulation and imaging experiment. The results demonstrated that our arrays have good decoupling between coils when they are on a curved surface with S21 coil array. Future work will empirically construct a multi-channel array with the number of channel matched to commercial phased array in order to validate the performance in vivo.

  15. Late Proterozoic extensional collapse in the Arabian-Nubian Shield

    OpenAIRE

    Blasband, B.B.; White, S H; Brooijmans, P.; Boorder, H. de; Visser, W.

    2000-01-01

    A structural and petrological study of the Late Proterozoic rocks in the Wadi Kid area, Sinai, Egypt indicates the presence of an extensional metamorphic core complex in the northern Arabian–Nubian Shield. Gneissic domes throughout the Arabian–Nubian Shield resemble the core complex of the Wadi Kid area and as a result, they are interpreted as extensional metamorphic core complexes. The presence of a widespread phase of extension at the end of the Pan-African period in the Arabian–Nubian Shie...

  16. Comparison between Clinically Used Irregular Fields Shielded by Cerrobend and Standard Lead Blocks

    Directory of Open Access Journals (Sweden)

    Farajollahi A. R.

    2015-06-01

    Full Text Available Introduction: In radiation therapy centers across Iran, protection of normal tissues is usually accomplished by either Cerrobend or lead block shielding. In this study, the influence of these two shielding methods on central axis dose distribution of photon beam a Cobalt unit was investigated in clinical conditions. Materials and Methods: All measurements were performed for 60Co γ-ray beams and the Cerrobend blocks were fabricated by commercial Cerrobend materials. Standard lead block shields belonged to Cobalt unit. Data was collected through a calibrated ionization chamber, relative dosimetry systems and a TLD dosimetery. Results: Results of the percent depth dose (PDD measurements at depths of 0.5, 1, 5, 10, 15 and 20 cm for 23 different field sizes of patients with head and neck cancer showed no significant differences between lead and Cerrobend shielding methods. Measurement results of absolute dosimetry in depths of 1.5, 3, 5, 7, 10 and 12 cm also showed no significant differences between these two shielding methods. The same results were obtained by TLD dosimetry on patient skin. Conclusion: Use of melt shielding methods is a very easy and fast shield-making technique with no differences in PDD, absolute and skin dose between lead and Cerrobend block shielding methods.

  17. Shielding examinations for the European Spallation Source ESS: Update for use by EURISOL

    CERN Document Server

    Rainer Moormann

    The Moyer model used in shielding design of the ESS accelerator is outlined in detail and relevant results are presented. General guidelines for shielding of a large spallation based system are presented, which take into account accidental beam losses and enhanced beam losses during start-up, too.

  18. Lithium hydride - A space age shielding material

    Science.gov (United States)

    Welch, F. H.

    1974-01-01

    Men and materials performing in the environment of an operating nuclear reactor require shielding from the escaping neutron particles and gamma rays. For efficient shielding from gamma rays, dense, high atomic number elements such as iron, lead, or tungsten are required, whereas light, low atomic number elements such as hydrogen, lithium, or beryllium are required for efficient neutron shielding. The use of lithium hydride (LiH) as a highly efficient neutron-shielding material is considered. It contains, combined into a single, stable compound, two of the elements most effective in attenuating and absorbing neutrons.

  19. Focused ion beam processing to fabricate ohmic contact electrodes on a bismuth nanowire for Hall measurements

    OpenAIRE

    Murata, Masayuki; Hasegawa, Yasuhiro

    2013-01-01

    Ohmic contact electrodes for four-wire resistance and Hall measurements were fabricated on an individual single-crystal bismuth nanowire encapsulated in a cylindrical quartz template. Focused ion beam processing was utilized to expose the side surfaces of the bismuth nanowire in the template, and carbon and tungsten electrodes were deposited on the bismuth nanowire in situ to achieve electrical contacts. The temperature dependence of the four-wire resistance was successfully measured for the ...

  20. Standard triple, bismuth pectin quadruple and sequential therapies for Helicobacter pylori eradication

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    AIM: To compare the effectiveness of standard triple, bismuth pectin quadruple and sequential therapies for Helicobacter pylori (H. pylori ) eradication in a randomized, double-blinded, comparative clinical trial in China. METHODS: A total of 215 H. pylori -positive patients were enrolled in the study and randomly allocated into three groups: group A (n = 72) received a 10-d bismuth pectin quadruple therapy (20 mg rabeprazole bid , 1000 mg amoxicillin bid , 100 mg bismuth pectin qid , and 500 mg levofloxaci...

  1. Evaluation of shielding parameters for heavy metal fluoride based tellurite-rich glasses for gamma ray shielding applications

    Science.gov (United States)

    Sayyed, M. I.; Lakshminarayana, G.; Kityk, I. V.; Mahdi, M. A.

    2017-10-01

    In this work, we have evaluated the γ-ray shielding parameters such as mass attenuation coefficient (μ/ρ), effective atomic number (Zeff), half value layer (HVL), mean free path (MFP) and exposure buildup factors (EBF) for heavy metal fluoride (PbF2) based tellurite-rich glasses. In addition, neutron total macroscopic cross sections (∑R) for these glasses were also calculated. The maximum value for μ/ρ, Zeff and ∑R was found for heavy metal (Bi2O3) oxide introduced glass. The results of the selected glasses have been compared, in terms of MFP with different glass systems. The shielding effectiveness of the selected glasses is found comparable or better than of common ones, which indicates that these glasses with suitable oxides could be developed for gamma ray shielding applications.

  2. Paddle-based rotating-shield brachytherapy

    Science.gov (United States)

    Liu, Yunlong; Flynn, Ryan T.; Kim, Yusung; Dadkhah, Hossein; Bhatia, Sudershan K.; Buatti, John M.; Xu, Weiyu; Wu, Xiaodong

    2015-01-01

    Purpose: The authors present a novel paddle-based rotating-shield brachytherapy (P-RSBT) method, whose radiation-attenuating shields are formed with a multileaf collimator (MLC), consisting of retractable paddles, to achieve intensity modulation in high-dose-rate brachytherapy. Methods: Five cervical cancer patients using an intrauterine tandem applicator were considered to assess the potential benefit of the P-RSBT method. The P-RSBT source used was a 50 kV electronic brachytherapy source (Xoft Axxent™). The paddles can be retracted independently to form multiple emission windows around the source for radiation delivery. The MLC was assumed to be rotatable. P-RSBT treatment plans were generated using the asymmetric dose–volume optimization with smoothness control method [Liu et al., Med. Phys. 41(11), 111709 (11pp.) (2014)] with a delivery time constraint, different paddle sizes, and different rotation strides. The number of treatment fractions (fx) was assumed to be five. As brachytherapy is delivered as a boost for cervical cancer, the dose distribution for each case includes the dose from external beam radiotherapy as well, which is 45 Gy in 25 fx. The high-risk clinical target volume (HR-CTV) doses were escalated until the minimum dose to the hottest 2 cm3 (D2cm3) of either the rectum, sigmoid colon, or bladder reached their tolerance doses of 75, 75, and 90 Gy3, respectively, expressed as equivalent doses in 2 Gy fractions (EQD2 with α/β = 3 Gy). Results: P-RSBT outperformed the two other RSBT delivery techniques, single-shield RSBT (S-RSBT) and dynamic-shield RSBT (D-RSBT), with a properly selected paddle size. If the paddle size was angled at 60°, the average D90 increases for the delivery plans by P-RSBT on the five cases, compared to S-RSBT, were 2.2, 8.3, 12.6, 11.9, and 9.1 Gy10, respectively, with delivery times of 10, 15, 20, 25, and 30 min/fx. The increases in HR-CTV D90, compared to D-RSBT, were 16.6, 12.9, 7.2, 3.7, and 1.7 Gy10

  3. Paddle-based rotating-shield brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yunlong; Xu, Weiyu [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 (United States); Flynn, Ryan T.; Kim, Yusung; Bhatia, Sudershan K.; Buatti, John M. [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Dadkhah, Hossein [Department of Biomedical Engineering, University of Iowa, 1402 Seamans Center, Iowa City, Iowa 52242 (United States); Wu, Xiaodong, E-mail: xiaodong-wu@uiowa.edu [Department of Electrical and Computer Engineering, University of Iowa, 4016 Seamans Center, Iowa City, Iowa 52242 and Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)

    2015-10-15

    Purpose: The authors present a novel paddle-based rotating-shield brachytherapy (P-RSBT) method, whose radiation-attenuating shields are formed with a multileaf collimator (MLC), consisting of retractable paddles, to achieve intensity modulation in high-dose-rate brachytherapy. Methods: Five cervical cancer patients using an intrauterine tandem applicator were considered to assess the potential benefit of the P-RSBT method. The P-RSBT source used was a 50 kV electronic brachytherapy source (Xoft Axxent™). The paddles can be retracted independently to form multiple emission windows around the source for radiation delivery. The MLC was assumed to be rotatable. P-RSBT treatment plans were generated using the asymmetric dose–volume optimization with smoothness control method [Liu et al., Med. Phys. 41(11), 111709 (11pp.) (2014)] with a delivery time constraint, different paddle sizes, and different rotation strides. The number of treatment fractions (fx) was assumed to be five. As brachytherapy is delivered as a boost for cervical cancer, the dose distribution for each case includes the dose from external beam radiotherapy as well, which is 45 Gy in 25 fx. The high-risk clinical target volume (HR-CTV) doses were escalated until the minimum dose to the hottest 2 cm{sup 3} (D{sub 2cm{sup 3}}) of either the rectum, sigmoid colon, or bladder reached their tolerance doses of 75, 75, and 90 Gy{sub 3}, respectively, expressed as equivalent doses in 2 Gy fractions (EQD2 with α/β = 3 Gy). Results: P-RSBT outperformed the two other RSBT delivery techniques, single-shield RSBT (S-RSBT) and dynamic-shield RSBT (D-RSBT), with a properly selected paddle size. If the paddle size was angled at 60°, the average D{sub 90} increases for the delivery plans by P-RSBT on the five cases, compared to S-RSBT, were 2.2, 8.3, 12.6, 11.9, and 9.1 Gy{sub 10}, respectively, with delivery times of 10, 15, 20, 25, and 30 min/fx. The increases in HR-CTV D{sub 90}, compared to D-RSBT, were 16

  4. Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation

    Directory of Open Access Journals (Sweden)

    Favazza CP

    2014-10-01

    Full Text Available Christopher P Favazza, Deirdre M King, Heidi A Edmonson, Joel P Felmlee, Phillip J Rossman, Nicholas J Hangiandreou, Robert E Watson, Krzysztof R Gorny Department of Radiology, Mayo Clinic, Rochester, MN, USA Abstract: Radiofrequency (RF shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (~1 dB of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices. Keywords: radiofrequency shield, magnetic resonance imaging, radiofrequency attenuation

  5. Electrowetting on dielectric-actuation of microdroplets of aqueous bismuth telluride nanoparticle suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Dash, Raj K [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Borca-Tasciuc, T [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Purkayastha, A [Materials Science and Engineering Department, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Ramanath, G [Materials Science and Engineering Department, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States)

    2007-11-28

    This work reports the actuation of droplets of nanofluid by the electrowetting on dielectric (EWOD) effect. The nanofluid is comprised of an aqueous (deionized water) suspension of 3 nm diameter bismuth telluride nanoparticles capped with thioglycolic acid (TGA). Microdroplets of nanofluid are cast on Si(001) wafers coated with 100 nm thick layers of silicon dioxide and AF Teflon. Applying an electric field between the substrate and an electrode immersed in the nanofluid droplet results in a strong change in the contact angle from 110{sup 0} to 84{sup 0} for a 0-60 V voltage range. The droplets of nanofluid exhibit enhanced stability and absence of contact angle saturation in the tested voltage range when compared with droplets of aqueous solutions of 0.01 M Na{sub 2}SO{sub 4} or thioglycolic acid in deionized water. We propose that ion generation due to capping-agent desorption is a key factor determining the EWOD effect in the bismuth telluride nanofluid along with the nanoparticle contribution to charge transport. Our results open up new vistas for using nanofluids for microscale actuator device applications.

  6. Structural analysis of bismuth nanowire by X-ray standing wave method

    CERN Document Server

    Saito, A; Kurata, T; Maruyama, J; Kuwahara, Y; Aono, M; Miki, K

    2003-01-01

    Bismuth forms perfect wires without any defects on a clean Si(001) surface. Despite the importance of this self-organized nanowire from the viewpoints of both surface science and device application, an analysis of the internal structure of the wire is quite difficult under the condition of a buried interface. In order to clarify the atomic structure of the wire capped by amorphous Si layers, the three-dimensional bismuth atomic site was measured with respect to the substrate Si lattice by the X-ray standing wave method. The results indicate that the absolute height of Bi atoms is 0.26 A upper from the bulklike Si(004) plane of the Si-dimer layer. For the structure inside the (004) plane, Bi atoms are in the range of +-0.5 A in the [110] direction from an intact Si-dimmer position. This result disagrees with recent reports that were derived from other analytical methods used solely for a clean surface. A new model was proposed and it suggests an influence of a burying effect for the wire structure. (author)

  7. Direct numerical simulation and statistical analysis of turbulent convection in lead-bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Otic, I.; Grotzbach, G. [Forschungszentrum Karlsruhe GmbH, Institut fuer Kern-und Energietechnik (Germany)

    2003-07-01

    Improved turbulent heat flux models are required to develop and analyze the reactor concept of an lead-bismuth cooled Accelerator-Driven-System. Because of specific properties of many liquid metals we have still no sensors for accurate measurements of the high frequency velocity fluctuations. So, the development of the turbulent heat transfer models which are required in our CFD (computational fluid dynamics) tools needs also data from direct numerical simulations of turbulent flows. We use new simulation results for the model problem of Rayleigh-Benard convection to show some peculiarities of the turbulent natural convection in lead-bismuth (Pr = 0.025). Simulations for this flow at sufficiently large turbulence levels became only recently feasible because this flow requires the resolution of very small velocity scales with the need for recording long-wave structures for the slow changes in the convective temperature field. The results are analyzed regarding the principle convection and heat transfer features. They are also used to perform statistical analysis to show that the currently available modeling is indeed not adequate for these fluids. Basing on the knowledge of the details of the statistical features of turbulence in this convection type and using the two-point correlation technique, a proposal for an improved statistical turbulence model is developed which is expected to account better for the peculiarities of the heat transfer in the turbulent convection in low Prandtl number fluids. (authors)

  8. Comparison between Clinically Used Irregular Fields Shielded by Cerrobend and Standard Lead Blocks.

    Science.gov (United States)

    Farajollahi, A R; Bouzarjomehri, F; Kiani, M

    2015-06-01

    In radiation therapy centers across Iran, protection of normal tissues is usually accomplished by either Cerrobend or lead block shielding. In this study, the influence of these two shielding methods on central axis dose distribution of photon beam a Cobalt unit was investigated in clinical conditions. All measurements were performed for 60Co γ-ray beams and the Cerrobend blocks were fabricated by commercial Cerrobend materials. Standard lead block shields belonged to Cobalt unit. Data was collected through a calibrated ionization chamber, relative dosimetry systems and a TLD dosimetery. Results of the percent depth dose (PDD) measurements at depths of 0.5, 1, 5, 10, 15 and 20 cm for 23 different field sizes of patients with head and neck cancer showed no significant differences between lead and Cerrobend shielding methods. Measurement results of absolute dosimetry in depths of 1.5, 3, 5, 7, 10 and 12 cm also showed no significant differences between these two shielding methods. The same results were obtained by TLD dosimetry on patient skin. Use of melt shielding methods is a very easy and fast shield-making technique with no differences in PDD, absolute and skin dose between lead and Cerrobend block shielding methods.

  9. Bismuth-induced Raman modes in GaP1- x Bi x

    Science.gov (United States)

    Christian, Theresa M.; Fluegel, Brian; Beaton, Daniel A.; Alberi, Kirstin; Mascarenhas, Angelo

    2016-10-01

    Dilute bismide semiconductor alloys are a promising material platform for optoelectronic devices due to drastic impacts of bismuth on the electronic structure of the alloy. At the same time, the details of bismuth incorporation in the lattice are not fully understood. In this work, we conduct Raman scattering spectroscopy on GaP1- x Bi x epilayers grown by molecular beam epitaxy (MBE) and identify several bismuth-related Raman features including gap vibration modes at 296, 303, and 314 cm-1. This study paves the way for more detailed analysis of the local symmetry at bismuth incorporation sites in the dilute bismide alloy regime.

  10. Nanophotonic Modulator with Bismuth Ferrite as Low-loss Switchable Material

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2015-01-01

    We propose a nanophotonic waveguide modulator with bismuth ferrite as a tunable material. Due to near-zero losses in bismuth ferrite, modulation with up to 20 dB/μm extinction ratio and 12 μm propagation length is achieved.......We propose a nanophotonic waveguide modulator with bismuth ferrite as a tunable material. Due to near-zero losses in bismuth ferrite, modulation with up to 20 dB/μm extinction ratio and 12 μm propagation length is achieved....

  11. Antibacterial effects of Bismuth compounds and it synergy with Tetracycline and Metronidazole on Helicobacter Pylori

    Directory of Open Access Journals (Sweden)

    Rajabie A

    1997-04-01

    Full Text Available Bismuth salts and different antimicrobials including Metonidazole & Tetracyclines were used in the assessment of inhibition zone of Helicobacter pylori cultures on solid media. Antibiotics were used or in combined in order to find out their possible synergistic effects. It was showed that: only Bismuth substrate and not then salts have antibacterial effects on Helicobacter pylori and also on the other bacteria such as staphylococci; salmonella and brulla. In addition, only Bismuth substrances showed remarkable synergistic effects with antimicrobial drugs against Helicobacter pylori. Therefore the data obtained from this investigation confirm previously known effect of combination antibiotic therapy including Bismuth compounds in eradicating Helicobacter pylori.

  12. Bismuth-Induced Raman Modes in GaP1-xBix

    Energy Technology Data Exchange (ETDEWEB)

    Christian, Theresa M.; Fluegel, Brian; Beaton, Daniel A.; Alberi, Kirstin; Mascarenhas, Angelo

    2016-10-01

    Dilute bismide semiconductor alloys are a promising material platform for optoelectronic devices due to drastic impacts of bismuth on the electronic structure of the alloy. At the same time, the details of bismuth incorporation in the lattice are not fully understood. In this work, we conduct Raman scattering spectroscopy on GaP1- x Bi x epilayers grown by molecular beam epitaxy (MBE) and identify several bismuth-related Raman features including gap vibration modes at 296, 303, and 314 cm-1. This study paves the way for more detailed analysis of the local symmetry at bismuth incorporation sites in the dilute bismide alloy regime.

  13. Preparation of high-purity bismuth by sulphur deleadization in vacuum distillation

    Institute of Scientific and Technical Information of China (English)

    熊利芝; 何则强; 刘文萍; 麻成金; 戴永年

    2004-01-01

    The feasibility of separation of impurities in refined bismuth and sulphur deleadization with vacuum distillation was studied theoretically. Experimental studies on sulphur deleadization were carried out under vacuum.The influences of amount of sulphur, distillation temperature, vacuum degree and distillation time on deleadization were investigated and an optimal technical condition was achieved. The content of lead in refined bismuth can be decreased from 30 μg/g to 0.21 μg/g, which has reached the level of "5N" high-purity bismuth. Other impurities in refined bismuth can be also removed effectively under certain conditions.

  14. Production cross sections of discrete gamma-ray resulting from interaction of 14. 2 MeV neutron with Pb and Bi

    Energy Technology Data Exchange (ETDEWEB)

    Wu Youngshun; Shen Ronglin; Shi Xiamin; Xing Jinqiang; Ding Dazhao

    1982-11-01

    The differential cross sections of gamma-rays produced in interation of 14.2 MeV neutron with natural lead and bismuth have been measured at 55/sup 0/ (lab). The complete shield Ge (Li) spectrometer with time-of-flight technique gated by associated particle in T(d,n) reaction was used. The gamma-ray spectra from 14.2 MeV neutron interactions with /sup 238/U and natural Tungsten have been measured as well. For Pb and Bi, tens of discrete gamma-rays were identified. Some of thme have not been reported in previous work. The effects of attenuation and multiple scattering of neutron and the gamma-ray self-absorption in sample are corrected by Monte-Carlo method. The experimental results are compared with others.

  15. Shielding of emitting dust particles

    Science.gov (United States)

    Luca Delzanno, Gian; Lapenta, Giovanni; Rosenberg, Marlene

    2003-10-01

    In the present work we focus on the role of electron emission (either thermionic or photoelectric) in charging an object immersed in a plasma. In fact, it is well known that the higher mobility of the plasma electrons (that would lead to negatively charged objects) can be overcome by electron emission, thus reversing the object polarity. Moreover, recent work [1] has shown how electron emission can fundamentally affect the shielding potential around the dust. In particular, depending on the physical parameters of the system (that were chosen such to correspond to common experimental conditions), the shielding potential can develop an attractive potential well. The aim of the present work is two-fold. First, we will present a parametric study in order to enlight the conditions for the formation, as well as the stability of the well. Furthermore, simulations will be presented with physical parameters corresponding to the ionosphere, thus extending our study to the case of meteroids. [1] G.L. Delzanno, G. Lapenta, M. Rosenberg, "Attractive Potential among Thermionically Emitting Microparticles", submitted.

  16. Influence of temperature on the oxidation/corrosion process of F82Hmod. martensitic steel in lead-bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Briceno, D.; Soler Crespo, L.; Martin Munoz, F.J.; Hernandez Arroyo, F

    2002-06-01

    A F82Hmod. martensitic steel has been tested in lead-bismuth under a gas atmosphere with a H{sub 2}/H{sub 2}O equilibrium of 0.3 to examine the influence of temperature on the oxidation/corrosion process. The temperature range studied was 535-550 deg. C, temperatures just below the temperature transformation of magnetite into wustite. The durations of the tests were 500 and 1000 h and the oxygen concentration in lead-bismuth was between 3x10{sup -7} and 4x10{sup -7} wt%. The results point out the existence of a threshold temperature, around 550 deg. C, above which corrosion occurs and the formation of a protective oxide layer is not possible. Two approaches have been considered to explain this behaviour: (a) a kinetic mechanism more than thermodynamic considerations as the driving force of the oxidation/corrosion in lead-bismuth under low oxygen potential, (b) the possible transformation of magnetite into wustite.

  17. Using nanostructured conductive carbon tape modified with bismuth as the disposable working electrode for stripping analysis in paper-based analytical devices.

    Science.gov (United States)

    Feng, Qiu-Mei; Zhang, Qing; Shi, Chuan-Guo; Xu, Jing-Juan; Bao, Ning; Gu, Hai-Ying

    2013-10-15

    Low cost disposable working electrodes are specifically desired for practical applications of electrochemical detection considering maturity of electrochemical stations and data collection protocols. In this paper double-sided conductive adhesive carbon tape with nanostructure was applied to fabricate disposable working electrodes. Being supported by indium tin oxide glass, the prepared carbon tape electrodes were coated with bismuth film for stripping analysis of heavy metal ions. By integrating the bismuth modified electrodes with paper-based analytical devices, we were able to differentiate Zn, Cd and Pb ions with the sample volume of around 15 μL. After the optimization of parameters, including modification of bismuth film and the area of the electrodes, etc., Pb ions could be measured in the linear range from 10 to 500 μg/L with the detection limit of 2 μg/L. Our experimental results revealed that the disposable modified electrodes could be used to quantify migrated lead from toys with the results agreed well with that using atomic absorption spectrometry. Although bismuth modification and stripping analysis could be influenced by the low conductivity of the carbon tape, the low cost disposable carbon tape electrodes take the advantages of large-scaled produced double-sided carbon tape, including its reproducible nanostructure and scaled-up fabrication process. In addition, the preparation of disposable electrodes avoids time-consuming pretreatment and experienced operation. This study implied that the carbon tape might be an alternative candidate for practical applications of electrochemical detection.

  18. Large area bismuth absorbers for X-ray microcalorimeters

    Energy Technology Data Exchange (ETDEWEB)

    Vaillancourt, J.E. E-mail: vaillancourt@wisp.physics.wisc.edu; Allen, C.A.; Brekosky, R.; Dosaj, A.; Galeazzi, M.; Kelley, R.; Liu, D.; McCammon, D.; Porter, F.S.; Rocks, L.E.; Sanders, W.T.; Stahle, C.K

    2004-03-11

    Two challenges facing the use of large area (2 mmx2 mm) bismuth absorbers for microcalorimetry are uncertainties in the heat capacity of bismuth and the effects of lateral heat conduction and position dependence due to the absorber's large size. We have measured the heat capacity of three Bi samples to be 0.3-0.6 J K{sup -1} m{sup -3} at 100 mK. These absorbers also exhibit response variations as phonons created by an X-ray event at an absorber edge will take longer to propagate to the thermometer attachment point than those at the absorber center. This effect may degrade the detector's energy resolution if the propagation time is not very short compared to the thermometer time constant. We show that the response of the largest absorber varies by {approx}4% across its area.

  19. Shielding experiment of heavy-ion produced neutrons using a tissue-equivalent proportional counter.

    Science.gov (United States)

    Nunomiya, T; Yonai, S; Takada, M; Fukumura, A; Nakamura, T

    2003-01-01

    A shielding experiment was performed at the HIMAC (Heavy Ion Medical Accelerator in Chiba), of National Institute of Radiological Sciences (NIRS), to measure neutron dose using a spherical TEPC (tissue-equivalent proportional counter) of 12.55 cm inner diameter. Neutrons are produced from a 5 cm thick stopping length Cu target bombarded by 400 MeV/nucleon C6+ ions and penetrate concrete or iron shields of various thicknesses at 0 degree to the beam direction. From this shielding experiment. y-distribution, mean lineal energy, absorbed dose, dose equivalent and mean-quality factor were obtained behind the shield as a function of shield thickness. The neutron dose attenuation lengths were also obtained as 126 g cm(-2) for concrete and 211 g cm(-2) for iron. The measured results were compared with the calculated results using the MARS Monte Carlo code.

  20. Application of Particle Swarm Optimization Algorithm in Design of Multilayered Planar Shielding Body

    Institute of Scientific and Technical Information of China (English)

    FUJiwei; HOUChaozhen; DOULihua

    2005-01-01

    Based on the basic electromagnetic wave propagation theory in this article, the Particle swarm optimization algorithm (PSO) is used in the design of the multilayered composite materials and the thickness of shielding body by the existent multilayered planar composite elec-tromagnetic shielding materials model, the different shielding materials of each layer can be designed under some kinds of circumstances: the prespecified Shielding effectiveness (SE), different incident angle and the prespecified band of frequencies. Finally the algorithm is simulated. At the same time the similar procedure can be implemented by Genetic algorithm (GA). The results acquired by particle swarm optimization algorithm are compared with there sults acquired by the genetic algorithm. The results indicate that: the particle swarm optimization algorithm is much better than the genetic algorithm not only in convergence speed but also in simplicity. So a more effective method (Particle Swarm Optimization algorithm) is offered for the design of the multilayered composite shielding materials.