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Sample records for showed large bi-directional

  1. Investigations of bi-directional flow behaviour of a large vertical opening in containment

    International Nuclear Information System (INIS)

    Sharma, Pavan K.; Markandeya, S.G.; Ghosh, A.K.; Kushwaha, H.S.

    2002-01-01

    Full text: In the complex codes developed for fire analysis and for containment thermal hydraulic analysis. The junction in the multi-compartment geometries are often modeled as uni-directional junctions. However, certain large size junctions are known to depict bi-directional flow behaviour under specific circumstances. Detailed investigations have been carried out to understand the bi-directionality of a junction by analyzing an earlier reported case study of fire in an enclosure. A computer code FDS was used for the analysis. The paper presents the details of the analysis, the results obtained and further studies required to be conducted so that the findings can be applied to the fire/containment thermal hydraulics analysis codes successfully

  2. Efficient parallel and out of core algorithms for constructing large bi-directed de Bruijn graphs

    Directory of Open Access Journals (Sweden)

    Vaughn Matthew

    2010-11-01

    Full Text Available Abstract Background Assembling genomic sequences from a set of overlapping reads is one of the most fundamental problems in computational biology. Algorithms addressing the assembly problem fall into two broad categories - based on the data structures which they employ. The first class uses an overlap/string graph and the second type uses a de Bruijn graph. However with the recent advances in short read sequencing technology, de Bruijn graph based algorithms seem to play a vital role in practice. Efficient algorithms for building these massive de Bruijn graphs are very essential in large sequencing projects based on short reads. In an earlier work, an O(n/p time parallel algorithm has been given for this problem. Here n is the size of the input and p is the number of processors. This algorithm enumerates all possible bi-directed edges which can overlap with a node and ends up generating Θ(nΣ messages (Σ being the size of the alphabet. Results In this paper we present a Θ(n/p time parallel algorithm with a communication complexity that is equal to that of parallel sorting and is not sensitive to Σ. The generality of our algorithm makes it very easy to extend it even to the out-of-core model and in this case it has an optimal I/O complexity of Θ(nlog(n/BBlog(M/B (M being the main memory size and B being the size of the disk block. We demonstrate the scalability of our parallel algorithm on a SGI/Altix computer. A comparison of our algorithm with the previous approaches reveals that our algorithm is faster - both asymptotically and practically. We demonstrate the scalability of our sequential out-of-core algorithm by comparing it with the algorithm used by VELVET to build the bi-directed de Bruijn graph. Our experiments reveal that our algorithm can build the graph with a constant amount of memory, which clearly outperforms VELVET. We also provide efficient algorithms for the bi-directed chain compaction problem. Conclusions The bi-directed

  3. Efficient parallel and out of core algorithms for constructing large bi-directed de Bruijn graphs.

    Science.gov (United States)

    Kundeti, Vamsi K; Rajasekaran, Sanguthevar; Dinh, Hieu; Vaughn, Matthew; Thapar, Vishal

    2010-11-15

    Assembling genomic sequences from a set of overlapping reads is one of the most fundamental problems in computational biology. Algorithms addressing the assembly problem fall into two broad categories - based on the data structures which they employ. The first class uses an overlap/string graph and the second type uses a de Bruijn graph. However with the recent advances in short read sequencing technology, de Bruijn graph based algorithms seem to play a vital role in practice. Efficient algorithms for building these massive de Bruijn graphs are very essential in large sequencing projects based on short reads. In an earlier work, an O(n/p) time parallel algorithm has been given for this problem. Here n is the size of the input and p is the number of processors. This algorithm enumerates all possible bi-directed edges which can overlap with a node and ends up generating Θ(nΣ) messages (Σ being the size of the alphabet). In this paper we present a Θ(n/p) time parallel algorithm with a communication complexity that is equal to that of parallel sorting and is not sensitive to Σ. The generality of our algorithm makes it very easy to extend it even to the out-of-core model and in this case it has an optimal I/O complexity of Θ(nlog(n/B)Blog(M/B)) (M being the main memory size and B being the size of the disk block). We demonstrate the scalability of our parallel algorithm on a SGI/Altix computer. A comparison of our algorithm with the previous approaches reveals that our algorithm is faster--both asymptotically and practically. We demonstrate the scalability of our sequential out-of-core algorithm by comparing it with the algorithm used by VELVET to build the bi-directed de Bruijn graph. Our experiments reveal that our algorithm can build the graph with a constant amount of memory, which clearly outperforms VELVET. We also provide efficient algorithms for the bi-directed chain compaction problem. The bi-directed de Bruijn graph is a fundamental data structure for

  4. Investigations of bi-directional flow behaviour in presence of a large vertical opening in a fire compartment

    International Nuclear Information System (INIS)

    Sharma, Pavan K.; Gera, B.

    2011-01-01

    In the complex thermal hydraulics codes developed for fire, reactor and containment safety the junctions in the multi-compartment geometries are often modeled as uni-directional junctions and some construct of flow coefficient. However, certain large size junctions are known to depict bi-directional flow behaviour under specific circumstances. The CFD based computer code FDS was used for an earlier reported study of fire in an enclosure on the bidirectional flow behaviour in present of a wall opening. Numerical simulation is directed to monitor the entrainment of the fresh air from outside to the fire compartment and resulting plume deflection due to presence of a big opening. The paper presents the details of the analysis, the results obtained, and comparison with the reported experimental data in terms of plume deflection, entrainment. Detailed investigations have been carried out to understand the bi-directionality of a junction by analyzing studying the outgoing hot air flow and incoming cold air. (orig.)

  5. Performance and cavitation characteristics of bi-directional hydrofoils

    Science.gov (United States)

    Nedyalkov, Ivaylo; Wosnik, Martin

    2013-11-01

    Tidal turbines extract energy from flows which reverse direction. One way to address this bi-directionality in horizontal axis turbines that avoid the use of complex and maintenance-intensive yaw or blade pitch mechanisms, is to design bi-directional blades which perform (equally) well in either flow direction. A large number of proposed hydrofoil designs were investigated using numerical simulations. Selected candidate foils were also tested (at various speeds and angles of attack) in the High-Speed Cavitation Tunnel (HICaT) at the University of New Hampshire. Lift and drag were measured using a force balance, and cavitation inception and desinence were recorded. Experimental and numerical results were compared, and the foils were compared to each other and to reference foils. Bi-directional hydrofoils may provide a feasible solution to the problem of reversing flow direction, when their performance and cavitation characteristics are comparable to those for unidirectional foils, and the penalty in decreased energy production is outweighed by the cost reduction due to lower complexity and respectively lower installation and maintenance costs.

  6. Magnetically actuated bi-directional microactuators with permalloy and Fe/Pt hard magnet

    International Nuclear Information System (INIS)

    Pan, C.T.; Shen, S.C.

    2005-01-01

    Bi-directional polyimide (PI) electromagnetic microactuator with different geometries are designed, fabricated and tested. Fabrication of the electromagnetic microactuator consists of 10 μm thick Ni/Fe (80/20) permalloy deposition on the PI diaphragm by electroplating, high aspect ratio electroplating of copper planar coil with 10 μm in thickness, bulk micromachining, and excimer laser selective ablation. They were fabricated by a novel concept avoiding the etching selectivity and residual stress problems during wafer etching. A mathematical model is created by ANSYS software to analyze the microactuator. The external magnetic field intensity (H ext ) generated by the planar coil is simulated by ANSYS software. ANSYS software is used to predict the deflection angle of the microactuator. Besides, to provide bi-directional and large deflection angle of microactuator, hard magnet Fe/Pt is deposited at a low temperature of 300 deg. C by sputtering onto the PI diaphragm to produce a perpendicular magnetic anisotropic field. This magnetic field can enhance the interaction with H ext to induce attractive and repulsive bi-directional force to provide large displacement. The results of magnetic microactuator with and without hard magnets are compared and discussed. The preliminary result reveals that the electromagnetic microactuator with hard magnet shows a greater deflection angle than that without one

  7. Bi-directional electrons in the near-Earth plasma sheet

    Directory of Open Access Journals (Sweden)

    K. Shiokawa

    2003-07-01

    Full Text Available We have studied the occurrence characteristics of bi-directional electron pitch angle anisotropy (enhanced flux in field-aligned directions, F^ /F|| > 1.5 at energies of 0.1–30 keV using plasma and magnetic field data from the AMPTE/IRM satellite in the near-Earth plasma sheet. The occurrence rate increases in the tailward direction from XGSM = - 9 RE to - 19 RE . The occurrence rate is also enhanced in the midnight sector, and furthermore, whenever the elevation angle of the magnetic field is large while the magnetic field intensity is small, B ~ 15 nT. From these facts, we conclude that the bi-directional electrons in the central plasma sheet are produced mainly in the vicinity of the neutral sheet and that the contribution from ionospheric electrons is minor. A high occurrence is also found after earthward high-speed ion flows, suggesting Fermi-type field-aligned electron acceleration in the neutral sheet. Occurrence characteristics of bi-directional electrons in the plasma sheet boundary layer are also discussed.Key words. Magnetospheric physics (magnetospheric configuration and dynamics; magnetotail; plasma sheet

  8. TOOL ASSEMBLY WITH BI-DIRECTIONAL BEARING

    Science.gov (United States)

    Longhurst, G.E.

    1961-07-11

    A two-direction motion bearing which is incorporated in a refueling nuclear fuel element trsnsfer tool assembly is described. A plurality of bi- directional bearing assembliesare fixed equi-distantly about the circumference of the transfer tool assembly to provide the tool assembly with a bearing surface- for both axial and rotational motion. Each bi-directional bearing assembly contains a plurality of circumferentially bulged rollers mounted in a unique arrangement which will provide a bearing surface for rotational movement of the tool assembly within a bore. The bi-direc tional bearing assembly itself is capable of rational motion and thus provides for longitudinal movement of the tool assembly.

  9. MR imaging of the brain in large cohort studies: feasibility report of the population- and patient-based BiDirect study

    International Nuclear Information System (INIS)

    Teuber, Anja; Berger, Klaus; Wersching, Heike; Sundermann, Benedikt; Kugel, Harald; Schwindt, Wolfram; Heindel, Walter; Minnerup, Jens; Dannlowski, Udo

    2017-01-01

    To describe the implementation and protocol of cerebral magnetic resonance imaging (MRI) in the longitudinal BiDirect study and to report rates of study participation as well as management of incidental findings. Data came from the BiDirect study that investigates the relationship between depression and arteriosclerosis and comprises 2258 participants in three cohorts: 999 patients with depression, 347 patients with manifest cardiovascular disease (CVD) and 912 population-based controls. The study program includes MRI of the brain. Reasons for non-participation were systematically collected. Incidental findings were categorized and disclosed according to clinical relevance. At baseline 2176 participants were offered MRI, of whom 1453 (67 %) completed it. Reasons for non-participation differed according to cohort, age and gender with controls showing the highest participation rate of 79 %. Patient cohorts had higher refusal rates and CVD patients a high prevalence of contraindications. In the first follow-up examination 69 % of participating subjects completed MRI. Incidental findings were disclosed to 246 participants (17 %). The majority of incidental findings were extensive white matter hyperintensities requiring further diagnostic work-up. Knowledge about subjects and sensible definition of incidental findings are crucial for large-scale imaging projects. Our data offer practical and concrete information for the design of future studies. (orig.)

  10. MR imaging of the brain in large cohort studies: feasibility report of the population- and patient-based BiDirect study

    Energy Technology Data Exchange (ETDEWEB)

    Teuber, Anja; Berger, Klaus; Wersching, Heike [University of Muenster, Institute of Epidemiology and Social Medicine, Muenster (Germany); Sundermann, Benedikt; Kugel, Harald; Schwindt, Wolfram; Heindel, Walter [University Hospital Muenster, Department of Clinical Radiology, Muenster (Germany); Minnerup, Jens [University Hospital Muenster, Department of Neurology, Muenster (Germany); Dannlowski, Udo [University of Muenster, Department of Psychiatry, Muenster (Germany); University of Marburg, Department of Psychiatry, Marburg (Germany)

    2017-01-15

    To describe the implementation and protocol of cerebral magnetic resonance imaging (MRI) in the longitudinal BiDirect study and to report rates of study participation as well as management of incidental findings. Data came from the BiDirect study that investigates the relationship between depression and arteriosclerosis and comprises 2258 participants in three cohorts: 999 patients with depression, 347 patients with manifest cardiovascular disease (CVD) and 912 population-based controls. The study program includes MRI of the brain. Reasons for non-participation were systematically collected. Incidental findings were categorized and disclosed according to clinical relevance. At baseline 2176 participants were offered MRI, of whom 1453 (67 %) completed it. Reasons for non-participation differed according to cohort, age and gender with controls showing the highest participation rate of 79 %. Patient cohorts had higher refusal rates and CVD patients a high prevalence of contraindications. In the first follow-up examination 69 % of participating subjects completed MRI. Incidental findings were disclosed to 246 participants (17 %). The majority of incidental findings were extensive white matter hyperintensities requiring further diagnostic work-up. Knowledge about subjects and sensible definition of incidental findings are crucial for large-scale imaging projects. Our data offer practical and concrete information for the design of future studies. (orig.)

  11. Neutrino bi-large mixings and family

    International Nuclear Information System (INIS)

    Bando, Masako; Obara, Midori

    2004-01-01

    After a brief review of quark-lepton relations in grand unified theories (GUT), we show that the Pati-Salam relation with only one type of Higgs field configuration with ''four zero symmetric texture'' can reproduce two large neutrino mixings as well as observed mass differences. This is quite in contrast to the case of SU(5) where bi-large mixings essentially come from the charged lepton sector with non-symmetric charged lepton mass matrix. (author)

  12. Direct synthesis of BiCuChO-type oxychalcogenides by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Pele, Vincent; Barreteau, Celine [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France); Berardan, David, E-mail: david.berardan@u-psud.fr [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France); Zhao, Lidong; Dragoe, Nita [Institut de Chimie Moléculaire et des Matériaux d’Orsay, Univ. Paris-Sud, UMR 8182, Orsay F-91405 (France); CNRS, Orsay F-91405 (France)

    2013-07-15

    We report on the direct synthesis of BiCuChO based materials by mechanical alloying (Ch=Se, Te). We show that contrary to the synthesis paths used in the previous reports dealing with this family of materials, which use costly annealings in closed silica tubes under controlled atmosphere, this new synthesis route enables the synthesis of pure phase materials at room temperature under air, with reasonable milling time. This synthesis procedure is easily scalable for large scale applications. - Highlights: • Phase pure BiCuSeO doped and undoped prepared by mechanical alloying. • Synthesis performed under air at room temperature. • Electrical properties similar to that of samples synthesized by a classical path.

  13. A New Bi-Directional Projection Model Based on Pythagorean Uncertain Linguistic Variable

    Directory of Open Access Journals (Sweden)

    Huidong Wang

    2018-04-01

    Full Text Available To solve the multi-attribute decision making (MADM problems with Pythagorean uncertain linguistic variable, an extended bi-directional projection method is proposed. First, we utilize the linguistic scale function to convert uncertain linguistic variable and provide a new projection model, subsequently. Then, to depict the bi-directional projection method, the formative vectors of alternatives and ideal alternatives are defined. Furthermore, a comparative analysis with projection model is conducted to show the superiority of bi-directional projection method. Finally, an example of graduate’s job option is given to demonstrate the effectiveness and feasibility of the proposed method.

  14. Piezoelectric power converter with bi-directional power transfer

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a bi-directional piezoelectric power converter com¬ prising a piezoelectric transformer. The piezoelectric transformer comprises an input electrode electrically coupled to a primary section of the piezoelectric transformer and an output electrode electrically...... coupled to an output section of the piezoelectric transformer to provide a transformer output signal. A bi-directional switching circuit is coupled between the output electrode and a DC or AC output voltage of the power converter. Forward and reverse current conducting periods of the bi......, a reverse current is conducted through the bi-directional switching circuit from the DC or AC output voltage to the output electrode to discharge the DC or AC output voltage and return power to the primary section of the piezoelectric transformer....

  15. Dynamical implications of bi-directional resource exchange within a meta-ecosystem.

    Science.gov (United States)

    Rodriguez, Marisabel Rodriguez; Kopp, Darin; Allen, Daniel; Kang, Yun

    2018-05-05

    The exchange of resources across ecosystem boundaries can have large impacts on ecosystem structures and functions at local and regional scales. In this article, we develop a simple model to investigate dynamical implications of bi-directional resource exchanges between two local ecosystems in a meta-ecosystem framework. In our model, we assume that (1) Each local ecosystem acts as both a resource donor and recipient, such that one ecosystem donating resources to another results in a cost to the donating system and a benefit to the recipient; and (2) The costs and benefits of the bi-directional resource exchange between two ecosystems are correlated in a nonlinear fashion. Our model could apply to the resource interactions between terrestrial and aquatic ecosystems that are supported by the literature. Our theoretical results show that bi-directional resource exchange between two ecosystems can indeed generate complicated dynamical outcomes, including the coupled ecosystems having amensalistic, antagonistic, competitive, or mutualistic interactions, with multiple alternative stable states depending on the relative costs and benefits. In addition, if the relative cost for resource exchange for an ecosystem is decreased or the relative benefit for resource exchange for an ecosystem is increased, the production of that ecosystem would increase; however, depending on the local environment, the production of the other ecosystem may increase or decrease. We expect that our work, by evaluating the potential outcomes of resource exchange theoretically, can facilitate empirical evaluations and advance the understanding of spatial ecosystem ecology where resource exchanges occur in varied ecosystems through a complicated network. Copyright © 2018. Published by Elsevier Inc.

  16. The structure of the polynomials in preconditioned BiCG algorithms and the switching direction of preconditioned systems

    OpenAIRE

    Itoh, Shoji; Sugihara, Masaaki

    2016-01-01

    We present a theorem that defines the direction of a preconditioned system for the bi-conjugate gradient (BiCG) method, and we extend it to preconditioned bi-Lanczos-type algorithms. We show that the direction of a preconditioned system is switched by construction and by the settings of the initial shadow residual vector. We analyze and compare the polynomial structures of four preconditioned BiCG algorithms.

  17. Estimation of Bi induced changes in the direct E{sub 0} band gap of III–V-Bi alloys and comparison with experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Samajdar, D.P., E-mail: dipprakash010@gmail.com; Dhar, S.

    2016-03-01

    Quantum dielectric Theory (QDT) is used to explain the band gap bowing effect observed in III–V-Bismides such as InSb{sub 1−x}Bi{sub x}, InAs{sub 1−x}Bi{sub x}, InP{sub 1−x}Bi{sub x}, GaSb{sub 1−x}Bi{sub x}, GaAs{sub 1−x}Bi{sub x} and GaP{sub 1−x}Bi{sub x.} The dependence of the direct E{sub 0} band gap for these alloys on Bi mole fraction is calculated using QDT which requires the evaluation of the bowing parameter c. The bowing parameter gives the deviation of the direct E{sub 0} band gap from the linear relationship of E{sub 0} with Bi mole fraction. The band gap reduction values obtained using QDT are compared with those calculated using Virtual Crystal approximation (VCA) and Valence Band Anticrossing (VBAC) model as well as with the reported experimental data and the results of the comparison shows excellent agreement.

  18. Bi-directional causality in California's electricity and natural-gas markets

    International Nuclear Information System (INIS)

    Woo, Chi-Keung; Olson, Arne; Horowitz, Ira; Luk, Stephen

    2006-01-01

    The Granger instantaneous-causality test is applied to explore the potential causal relationships between wholesale electricity and natural-gas prices in California. The test shows these relationships to be bi-directional, and reveals California's electricity and natural-gas markets to be as inextricably intertwined as casual observation and theoretical considerations would suggest they ought to be. This meshing of markets exacerbated the effects of California's natural-gas crisis on the contemporaneous electricity crisis, while concurrently the electricity crisis may have contributed to the dysfunction in the national-gas market and helped to precipitate the natural-gas crisis. The finding supports an integrated approach, as opposed to a piecemeal approach, for formulating energy policy recommendations, not just in California but in the world at large

  19. Crowdsourced bi-directional disaster reporting and alerting on smartphones in Lao PDR

    OpenAIRE

    Frommberger, Lutz; Schmid, Falko

    2013-01-01

    Natural disasters are a large threat for people especially in developing countries such as Laos. ICT-based disaster management systems aim at supporting disaster warning and response efforts. However, the ability to directly communicate in both directions between local and administrative level is often not supported, and a tight integration into administrative workflows is missing. In this paper, we present the smartphone-based disaster and reporting system Mobile4D. It allows for bi-directio...

  20. Bi-directional SIFT predicts a subset of activating mutations.

    Directory of Open Access Journals (Sweden)

    William Lee

    Full Text Available Advancements in sequencing technologies have empowered recent efforts to identify polymorphisms and mutations on a global scale. The large number of variations and mutations found in these projects requires high-throughput tools to identify those that are most likely to have an impact on function. Numerous computational tools exist for predicting which mutations are likely to be functional, but none that specifically attempt to identify mutations that result in hyperactivation or gain-of-function. Here we present a modified version of the SIFT (Sorting Intolerant from Tolerant algorithm that utilizes protein sequence alignments with homologous sequences to identify functional mutations based on evolutionary fitness. We show that this bi-directional SIFT (B-SIFT is capable of identifying experimentally verified activating mutants from multiple datasets. B-SIFT analysis of large-scale cancer genotyping data identified potential activating mutations, some of which we have provided detailed structural evidence to support. B-SIFT could prove to be a valuable tool for efforts in protein engineering as well as in identification of functional mutations in cancer.

  1. Safety design of Pb-Bi-cooled direct contact boiling water fast reactor (PBWFR)

    International Nuclear Information System (INIS)

    Takahashi, Minoru; Uchida, Shoji; Yamada, Yumi; Koyama, Kazuya

    2008-01-01

    In Pb-Bi-cooled direct contact boiling water small fast reactor (PBWFR), steam is generated by direct contact of feedwater with primary Pb-Bi coolant above the core, and Pb-Bi coolant is circulated by steam lift pump in chimneys. Safety design has been developed to show safety features of PBWFR. Negative void reactivity is inserted even if whole of the core and upper plenum are voided hypothetically by steam intrusion from above. The control rod ejection due to coolant pressure is prevented using in-vessel type control rod driving mechanism. At coolant leak from reactor vessel and feedwater pipes, Pb-Bi coolant level in the reactor vessel required for decay heat removal is kept using closed guard vessel. Dual pipes for feedwater are employed to avoid leak of water. Although there is no concern of loss of flow accident due to primary pump trip, feedwater pump trip initiates loss of coolant flow (LOF). Injection of high pressure water slows down the flow coast down of feedwater at the LOF event. The unprotected loss of flow and heat sink (ATWS) has been evaluated, which shows that the fuel temperatures are kept lower than the safety limits. (author)

  2. Integrating high dimensional bi-directional parsing models for gene mention tagging.

    Science.gov (United States)

    Hsu, Chun-Nan; Chang, Yu-Ming; Kuo, Cheng-Ju; Lin, Yu-Shi; Huang, Han-Shen; Chung, I-Fang

    2008-07-01

    Tagging gene and gene product mentions in scientific text is an important initial step of literature mining. In this article, we describe in detail our gene mention tagger participated in BioCreative 2 challenge and analyze what contributes to its good performance. Our tagger is based on the conditional random fields model (CRF), the most prevailing method for the gene mention tagging task in BioCreative 2. Our tagger is interesting because it accomplished the highest F-scores among CRF-based methods and second over all. Moreover, we obtained our results by mostly applying open source packages, making it easy to duplicate our results. We first describe in detail how we developed our CRF-based tagger. We designed a very high dimensional feature set that includes most of information that may be relevant. We trained bi-directional CRF models with the same set of features, one applies forward parsing and the other backward, and integrated two models based on the output scores and dictionary filtering. One of the most prominent factors that contributes to the good performance of our tagger is the integration of an additional backward parsing model. However, from the definition of CRF, it appears that a CRF model is symmetric and bi-directional parsing models will produce the same results. We show that due to different feature settings, a CRF model can be asymmetric and the feature setting for our tagger in BioCreative 2 not only produces different results but also gives backward parsing models slight but constant advantage over forward parsing model. To fully explore the potential of integrating bi-directional parsing models, we applied different asymmetric feature settings to generate many bi-directional parsing models and integrate them based on the output scores. Experimental results show that this integrated model can achieve even higher F-score solely based on the training corpus for gene mention tagging. Data sets, programs and an on-line service of our gene

  3. Outpatient blood pressure monitoring using bi-directional text messaging.

    Science.gov (United States)

    Anthony, Chris A; Polgreen, Linnea A; Chounramany, James; Foster, Eric D; Goerdt, Christopher J; Miller, Michelle L; Suneja, Manish; Segre, Alberto M; Carter, Barry L; Polgreen, Philip M

    2015-05-01

    To diagnose hypertension, multiple blood pressure (BP) measurements are recommended. We randomized patients into three groups: EMR-only (patients recorded BP measurements in an electronic medical record [EMR] web portal), EMR + reminders (patients were sent text message reminders to record their BP measurements in the EMR), and bi-directional text messaging (patients were sent a text message asking them to respond with their current BP). Subjects were asked to complete 14 measurements. Automated messages were sent to each patient in the bi-directional text messaging and EMR + reminder groups twice daily. Among 121 patients, those in the bi-directional text messaging group reported the full 14 measurements more often than both the EMR-only group (P text messaging is an effective way to gather patient BP data. Text-message-based reminders alone are an effective way to encourage patients to record BP measurements. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  4. Fast bi-directional prediction selection in H.264/MPEG-4 AVC temporal scalable video coding.

    Science.gov (United States)

    Lin, Hung-Chih; Hang, Hsueh-Ming; Peng, Wen-Hsiao

    2011-12-01

    In this paper, we propose a fast algorithm that efficiently selects the temporal prediction type for the dyadic hierarchical-B prediction structure in the H.264/MPEG-4 temporal scalable video coding (SVC). We make use of the strong correlations in prediction type inheritance to eliminate the superfluous computations for the bi-directional (BI) prediction in the finer partitions, 16×8/8×16/8×8 , by referring to the best temporal prediction type of 16 × 16. In addition, we carefully examine the relationship in motion bit-rate costs and distortions between the BI and the uni-directional temporal prediction types. As a result, we construct a set of adaptive thresholds to remove the unnecessary BI calculations. Moreover, for the block partitions smaller than 8 × 8, either the forward prediction (FW) or the backward prediction (BW) is skipped based upon the information of their 8 × 8 partitions. Hence, the proposed schemes can efficiently reduce the extensive computational burden in calculating the BI prediction. As compared to the JSVM 9.11 software, our method saves the encoding time from 48% to 67% for a large variety of test videos over a wide range of coding bit-rates and has only a minor coding performance loss. © 2011 IEEE

  5. Bi-directional interhemispheric inhibition during unimanual sustained contractions

    Directory of Open Access Journals (Sweden)

    Ni Zhen

    2009-04-01

    Full Text Available Abstract Background The interaction between homologous muscle representations in the right and left primary motor cortex was studied using a paired-pulse transcranial magnetic stimulation (TMS protocol known to evoke interhemispheric inhibition (IHI. The timecourse and magnitude of IHI was studied in fifteen healthy right-handed adults at several interstimulus intervals between the conditioning stimulus and test stimulus (6, 8, 10, 12, 30, 40, 50 ms. IHI was studied in the motor dominant to non-dominant direction and vice versa while the right or left hand was at rest, performing isometric contraction of the first dorsal interosseous (FDI muscle, and isometric contraction of the FDI muscle in the context of holding a pen. Results Compared with rest, IHI was reduced at all ISIs during contraction of either type (with or without the context of pen. IHI was reduced bi-directionally without evidence of hemispheric dominance. Further, contraction of the hand contralateral to the conditioning and test pulse yielded similar reductions in IHI. Conclusion These data provide evidence for bi-directional reduction of IHI during unimanual contractions. During unimanual, sustained contractions of the hand, the contralateral and ipsilateral motor cortices demonstrate reduced inhibition. The data suggest that unimanual movement decreases inhibition bi-directionally across motor hemispheres and offer one explanation for the observation of ipsilateral M1 activity during hand movements.

  6. On Training Bi-directional Neural Network Language Model with Noise Contrastive Estimation

    OpenAIRE

    He, Tianxing; Zhang, Yu; Droppo, Jasha; Yu, Kai

    2016-01-01

    We propose to train bi-directional neural network language model(NNLM) with noise contrastive estimation(NCE). Experiments are conducted on a rescore task on the PTB data set. It is shown that NCE-trained bi-directional NNLM outperformed the one trained by conventional maximum likelihood training. But still(regretfully), it did not out-perform the baseline uni-directional NNLM.

  7. A new low threshold bi-directional wind vane and its potential impact on unplanned atmospheric release prediction

    International Nuclear Information System (INIS)

    Parker, M.J.

    1996-01-01

    At the Savannah River Site, the Environmental Transport Group (ETG) maintains and develops a comprehensive meteorological monitoring program which employs bi-directional wind vanes (bivanes) for the measurement of horizontal and vertical wind direction and turbulence. Wind data collected near and below instrument starting thresholds under stable nighttime conditions with these bivanes can result in artificially large standard deviations of horizontal wind direction (σA). In one hypothetical case, downwind concentrations could be underestimated by a factor of 40 by using artificially high σA data in a Gaussian dispersion model. In an effort to improve low wind speed measurements of wind direction, a Cooperative Research and Development Agreement (CRADA) between Met One Instruments and the Westinghouse Savannah River Company (WSRC) has been created to improve the dynamic performance of the Met One Model 1585 Bi-Directional Wind Vane

  8. Silent and Efficient Supersonic Bi-Directional Flying Wing

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a Phase I study for a novel concept of a supersonic bi-directional (SBiDir) flying wing (FW) that has the potential to revolutionize supersonic flight...

  9. Analysis of bi-directional piezoelectric-based converters for zero-voltage switching operation

    DEFF Research Database (Denmark)

    Ekhtiari, Marzieh; Zhang, Zhe; Andersen, Michael A. E.

    2016-01-01

    This paper deals with a thorough analysis of zerovoltage switching especially for bi-directional, inductorless, piezoelectric transformer-based switch-mode power supplies with a half-bridge topology. Practically, obtaining zero-voltage switching for all of the switches in a bi-directional piezoel......This paper deals with a thorough analysis of zerovoltage switching especially for bi-directional, inductorless, piezoelectric transformer-based switch-mode power supplies with a half-bridge topology. Practically, obtaining zero-voltage switching for all of the switches in a bi......-directional piezoelectric power converter is a difficult task. However, the analysis in this work will be convenient for overcoming this challenge. The analysis defines the zero-voltage region indicating the operating points whether or not soft switching can be met over the switching frequency and load range. For the first...... time, a comprehensive analysis is provided, which can be used as a design guideline for applying control techniques in order to drive switches in piezoelectric transformer-based converters. This study further conveys the proposed method to the region where all the switches can obtain soft switching...

  10. Developments of high strength Bi-containing Sn0.7Cu lead-free solder alloys prepared by directional solidification

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiaowu, E-mail: xwhmaterials@aliyun.com [School of Mechanical Electrical Engineering, Nanchang University, Nanchang 330031 (China); Li, Yulong [School of Mechanical Electrical Engineering, Nanchang University, Nanchang 330031 (China); Liu, Yi [School of Materials Science and Engineering, Nanchang University, Nanchang 330031 (China); Min, Zhixian [China Electronics Technology Group Corporation No. 38 Research Institute, Hefei 230088 (China)

    2015-03-15

    Highlights: • The Sn0.7Cu–xBi solder alloys were directionally solidified. • Both spacing and diameter of fibers decreased with increasing solidification rate. • The UTS and YS first increased with increased solidification rate, then decreased. • The UTS and YS of Sn0.7Cu–xBi first increased with increased Bi content. - Abstract: Bi-containing Sn0.7Cu (SC) eutectic solder alloys were prepared and subjected to directional solidification, through which new types of fiber reinforced eutectic composites were generated. The influences of Bi addition on the microstructures and tensile properties of directionally solidified (DS) Bi-containing eutectic SC lead-free solder alloys have been investigated by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and a tensile testing machine. The experimental results showed that addition of Bi could effectively reduce both the melting temperature and undercooling of SC solder alloy. The microstructures of DS SC–xBi solder alloys were composed of Sn-rich phase (β) and Cu{sub 6}Sn{sub 5} fiber. No other intermetallic compounds (IMCs) with Bi content were observed in the solder matrix for SC solder alloys with various Bi contents. Both fiber spacing and diameter all decreased gradually with increasing growth rate and/or Bi content. Besides, the regularity of Cu{sub 6}Sn{sub 5} fibers alignment also decreased with increasing growth rate, too. The tensile strengths of the SC–xBi eutectic solder alloys varied parabolically with growth rate (R). When R was 60 μm/s, maximum tensile strengths of 43.8, 55.2 and 56.37 MPa were reached for SC, SC0.7Bi and SC1.3Bi solder alloys. A comparison of tensile strength of SC, SC0.7Bi and SC1.3Bi with the same R indicated that the tensile strength increased with increasing Bi content, which was attributed to the presence of Bi and its role in refining microstructure and solid solution strengthening.

  11. Design of medium band gap Ag-Bi-Nb-O and Ag-Bi-Ta-O semiconductors for driving direct water splitting with visible light.

    Science.gov (United States)

    Wang, Limin; Cao, Bingfei; Kang, Wei; Hybertsen, Mark; Maeda, Kazuhiko; Domen, Kazunari; Khalifah, Peter G

    2013-08-19

    Two new metal oxide semiconductors belonging to the Ag-Bi-M-O (M = Nb, Ta) chemical systems have been synthesized as candidate compounds for driving overall water splitting with visible light on the basis of cosubstitution of Ag and Bi on the A-site position of known Ca2M2O7 pyrochlores. The low-valence band edge energies of typical oxide semiconductors prevents direct water splitting in compounds with band gaps below 3.0 eV, a limitation which these compounds are designed to overcome through the incorporation of low-lying Ag 4d(10) and Bi 6s(2) states into compounds of nominal composition "AgBiM2O7". It was found that the "AgBiTa2O7" pyrochlores are in fact a solid solution with an approximate range of Ag(x)Bi(5/6)Ta2O(6.25+x/2) with 0.5 semiconductors with the onset of strong direct absorption at 2.72 and 2.96 eV, respectively. Electronic structure calculations for an ordered AgBiNb2O7 structure show that the band gap reduction and the elevation of the valence band primarily result from hybridized Ag d(10)-O 2p orbitals that lie at higher energy than the normal O 2p states in typical pyrochlore oxides. While the minimum energy gap is direct in the band structure, the lowest energy dipole allowed optical transitions start about 0.2 eV higher in energy than the minimum energy transition and involve different bands. This suggests that the minimum electronic band gap in these materials is slightly smaller than the onset energy for strong absorption in the optical measurements. The elevated valence band energies of the niobate and tantalate compounds are experimentally confirmed by the ability of these compounds to reduce 2 H(+) to H2 gas when illuminated after functionalization with a Pt cocatalyst.

  12. Bi-directional Multi Dimension CAP Transmission for Smart Grid Communication Services

    DEFF Research Database (Denmark)

    Zhang, Xu; Binti Othman, Maisara; Pang, Xiaodan

    2012-01-01

    We experimentally demonstrate bi-directional multi dimension carrierless amplitude and phase (CAP) transmission for smart grid communication services based on optical fiber networks. The proposed system is able to support multi-Gb/s transmission with high spectral efficiency.......We experimentally demonstrate bi-directional multi dimension carrierless amplitude and phase (CAP) transmission for smart grid communication services based on optical fiber networks. The proposed system is able to support multi-Gb/s transmission with high spectral efficiency....

  13. Bi-directional magnetic resonance based wireless power transfer for electronic devices

    International Nuclear Information System (INIS)

    Kar, Durga P.; Nayak, Praveen P.; Bhuyan, Satyanarayan; Mishra, Debasish

    2015-01-01

    In order to power or charge electronic devices wirelessly, a bi-directional wireless power transfer method has been proposed and experimentally investigated. In the proposed design, two receiving coils are used on both sides of a transmitting coil along its central axis to receive the power wirelessly from the generated magnetic fields through strongly coupled magnetic resonance. It has been observed experimentally that the maximum power transfer occurs at the operating resonant frequency for optimum electric load connected across the receiving coils on both side. The optimum wireless power transfer efficiency is 88% for the bi-directional power transfer technique compared 84% in the one side receiver system. By adopting the developed bi-directional power transfer method, two electronic devices can be powered up or charged simultaneously instead of a single device through usual one side receiver system without affecting the optimum power transfer efficiency

  14. Bi-directional magnetic resonance based wireless power transfer for electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Kar, Durga P.; Nayak, Praveen P.; Bhuyan, Satyanarayan; Mishra, Debasish [Department of Electronics and Instrumentation Engineering, Institute of Technical Education and Research, Siksha ‘O’ Anushandhan University, Bhubaneswar 751030 (India)

    2015-09-28

    In order to power or charge electronic devices wirelessly, a bi-directional wireless power transfer method has been proposed and experimentally investigated. In the proposed design, two receiving coils are used on both sides of a transmitting coil along its central axis to receive the power wirelessly from the generated magnetic fields through strongly coupled magnetic resonance. It has been observed experimentally that the maximum power transfer occurs at the operating resonant frequency for optimum electric load connected across the receiving coils on both side. The optimum wireless power transfer efficiency is 88% for the bi-directional power transfer technique compared 84% in the one side receiver system. By adopting the developed bi-directional power transfer method, two electronic devices can be powered up or charged simultaneously instead of a single device through usual one side receiver system without affecting the optimum power transfer efficiency.

  15. Moral judgment modulation by disgust is bi-directionally moderated by individual sensitivity

    Directory of Open Access Journals (Sweden)

    How Hwee eOng

    2014-03-01

    Full Text Available Modern theories of moral judgment predict that both conscious reasoning and unconscious emotional influences affect the way people decide about right and wrong. In a series of experiments, we tested the effect of subliminal and conscious priming of disgust facial expressions on moral dilemmas. Trolley-car-type scenarios were used, with subjects rating how acceptable they found the utilitarian course of action to be. On average, subliminal priming of disgust facial expressions resulted in higher rates of utilitarian judgments compared to neutral facial expressions. Further, in replication, we found that individual change in moral acceptability ratings due to disgust priming was modulated by individual sensitivity to disgust, revealing a bi-directional function. Our second replication extended this result to show that the function held for both subliminally and consciously presented stimuli. Combined across these experiments, we show a reliable bi-directional function, with presentation of disgust expression primes to individuals with higher disgust sensitivity resulting in more utilitarian judgments (i.e., number-based and presentations to individuals with lower sensitivity resulting in more deontological judgments (i.e., rules-based. Our results may reconcile previous conflicting reports of disgust modulation of moral judgment by modeling how individual sensitivity to disgust determines the direction and degree of this effect.

  16. Moral judgment modulation by disgust is bi-directionally moderated by individual sensitivity

    Science.gov (United States)

    Ong, How Hwee; Mullette-Gillman, O’Dhaniel A.; Kwok, Kenneth; Lim, Julian

    2014-01-01

    Modern theories of moral judgment predict that both conscious reasoning and unconscious emotional influences affect the way people decide about right and wrong. In a series of experiments, we tested the effect of subliminal and conscious priming of disgust facial expressions on moral dilemmas. “Trolley-car”-type scenarios were used, with subjects rating how acceptable they found the utilitarian course of action to be. On average, subliminal priming of disgust facial expressions resulted in higher rates of utilitarian judgments compared to neutral facial expressions. Further, in replication, we found that individual change in moral acceptability ratings due to disgust priming was modulated by individual sensitivity to disgust, revealing a bi-directional function. Our second replication extended this result to show that the function held for both subliminally and consciously presented stimuli. Combined across these experiments, we show a reliable bi-directional function, with presentation of disgust expression primes to individuals with higher disgust sensitivity resulting in more utilitarian judgments (i.e., number-based) and presentations to individuals with lower sensitivity resulting in more deontological judgments (i.e., rules-based). Our results may reconcile previous conflicting reports of disgust modulation of moral judgment by modeling how individual sensitivity to disgust determines the direction and degree of this effect. PMID:24639665

  17. A New Bi-Directional Projection Model Based on Pythagorean Uncertain Linguistic Variable

    OpenAIRE

    Huidong Wang; Shifan He; Xiaohong Pan

    2018-01-01

    To solve the multi-attribute decision making (MADM) problems with Pythagorean uncertain linguistic variable, an extended bi-directional projection method is proposed. First, we utilize the linguistic scale function to convert uncertain linguistic variable and provide a new projection model, subsequently. Then, to depict the bi-directional projection method, the formative vectors of alternatives and ideal alternatives are defined. Furthermore, a comparative analysis with projection model is co...

  18. Learning to Monitor Machine Health with Convolutional Bi-Directional LSTM Networks.

    Science.gov (United States)

    Zhao, Rui; Yan, Ruqiang; Wang, Jinjiang; Mao, Kezhi

    2017-01-30

    In modern manufacturing systems and industries, more and more research efforts have been made in developing effective machine health monitoring systems. Among various machine health monitoring approaches, data-driven methods are gaining in popularity due to the development of advanced sensing and data analytic techniques. However, considering the noise, varying length and irregular sampling behind sensory data, this kind of sequential data cannot be fed into classification and regression models directly. Therefore, previous work focuses on feature extraction/fusion methods requiring expensive human labor and high quality expert knowledge. With the development of deep learning methods in the last few years, which redefine representation learning from raw data, a deep neural network structure named Convolutional Bi-directional Long Short-Term Memory networks (CBLSTM) has been designed here to address raw sensory data. CBLSTM firstly uses CNN to extract local features that are robust and informative from the sequential input. Then, bi-directional LSTM is introduced to encode temporal information. Long Short-Term Memory networks(LSTMs) are able to capture long-term dependencies and model sequential data, and the bi-directional structure enables the capture of past and future contexts. Stacked, fully-connected layers and the linear regression layer are built on top of bi-directional LSTMs to predict the target value. Here, a real-life tool wear test is introduced, and our proposed CBLSTM is able to predict the actual tool wear based on raw sensory data. The experimental results have shown that our model is able to outperform several state-of-the-art baseline methods.

  19. Learning to Monitor Machine Health with Convolutional Bi-Directional LSTM Networks

    Directory of Open Access Journals (Sweden)

    Rui Zhao

    2017-01-01

    Full Text Available In modern manufacturing systems and industries, more and more research efforts have been made in developing effective machine health monitoring systems. Among various machine health monitoring approaches, data-driven methods are gaining in popularity due to the development of advanced sensing and data analytic techniques. However, considering the noise, varying length and irregular sampling behind sensory data, this kind of sequential data cannot be fed into classification and regression models directly. Therefore, previous work focuses on feature extraction/fusion methods requiring expensive human labor and high quality expert knowledge. With the development of deep learning methods in the last few years, which redefine representation learning from raw data, a deep neural network structure named Convolutional Bi-directional Long Short-Term Memory networks (CBLSTM has been designed here to address raw sensory data. CBLSTM firstly uses CNN to extract local features that are robust and informative from the sequential input. Then, bi-directional LSTM is introduced to encode temporal information. Long Short-Term Memory networks(LSTMs are able to capture long-term dependencies and model sequential data, and the bi-directional structure enables the capture of past and future contexts. Stacked, fully-connected layers and the linear regression layer are built on top of bi-directional LSTMs to predict the target value. Here, a real-life tool wear test is introduced, and our proposed CBLSTM is able to predict the actual tool wear based on raw sensory data. The experimental results have shown that our model is able to outperform several state-of-the-art baseline methods.

  20. High electrical conductivity in out of plane direction of electrodeposited Bi2Te3 films

    Directory of Open Access Journals (Sweden)

    Miguel Muñoz Rojo

    2015-08-01

    Full Text Available The out of plane electrical conductivity of highly anisotropic Bi2Te3 films grown via electro-deposition process was determined using four probe current-voltage measurements performed on 4.6 - 7.2 μm thickness Bi2Te3 mesa structures with 80 - 120 μm diameters sandwiched between metallic film electrodes. A three-dimensional finite element model was used to predict the electric field distribution in the measured structures and take into account the non-uniform distribution of the current in the electrodes in the vicinity of the probes. The finite-element modeling shows that significant errors could arise in the measured film electrical conductivity if simpler one-dimensional models are employed. A high electrical conductivity of (3.2 ± 0.4 ⋅ 105 S/m is reported along the out of plane direction for Bi2Te3 films highly oriented in the [1 1 0] direction.

  1. Quantum spin Hall insulator BiXH (XH = OH, SH) monolayers with a large bulk band gap.

    Science.gov (United States)

    Hu, Xing-Kai; Lyu, Ji-Kai; Zhang, Chang-Wen; Wang, Pei-Ji; Ji, Wei-Xiao; Li, Ping

    2018-05-16

    A large bulk band gap is critical for the application of two-dimensional topological insulators (TIs) in spintronic devices operating at room temperature. On the basis of first-principles calculations, we predict BiXH (X = OH, SH) monolayers as TIs with an extraordinarily large bulk gap of 820 meV for BiOH and 850 meV for BiSH, and propose a tight-binding model considering spin-orbit coupling to describe the electronic properties of BiXH. These large gaps are entirely due to the strong spin-orbit interaction related to the pxy orbitals of the Bi atoms of the honeycomb lattice. The orbital filtering mechanism can be used to understand the topological properties of BiXH. The XH groups simply remove one branch of orbitals (pz of Bi) and reduce the trivial 6-band lattice into a 4-band, which is topologically non-trivial. The topological characteristics of BiXH monolayers are confirmed by nonzero topological invariant Z2 and a single pair of gapless helical edge states in the bulk gap. Owing to these features, the BiXH monolayers of the large-gap TIs are an ideal platform to realize many exotic phenomena and fabricate new quantum devices working at room temperature.

  2. Analysis of Bi-directional Effects on the Response of a Seismic Base Isolation System

    International Nuclear Information System (INIS)

    Park, Hyung-Kui; Kim, Jung-Han; Kim, Min Kyu; Choi, In-Kil

    2014-01-01

    The floor response spectrum depends on the height of the floor of the structure. Also FRS depends on the characteristics of the seismic base isolation system such as the natural frequency, damping ratio. In the previous study, the floor response spectrum of the base isolated structure was calculated for each axis without considering bi-directional effect. However, the shear behavior of the seismic base isolation system of two horizontal directions are correlated each other by the bi-directional effects. If the shear behavior of the seismic isolation system changes, it can influence the floor response spectrum and displacement response of isolators. In this study, the analysis of a bi-directional effect on the floor response spectrum was performed. In this study, the response of the seismic base isolation system based on the bi-directional effects was analyzed. By analyzing the time history result, while there is no alteration in the maximum shear force of seismic base isolation system, it is confirmed that the shear force is generally more decreased in a one-directional that in a two-directional in most parts. Due to the overall decreased shear force, the floor response spectrum is more reduced in a two-directional than in a one-directional

  3. Large-scale one-dimensional Bi x O y I z nanostructures: synthesis, characterization, and photocatalytic applications

    Science.gov (United States)

    Liu, Chaohong; Zhang, Dun

    2015-03-01

    The performances of Bi x O y I z photofunctional materials are very sensitive to their composition and microstructures; however, the morphology evolution and crystallization process of one-dimensional Bi x O y I z nanostructures, the roles of experimental factors, and related reaction mechanisms remain poorly understood. In this work, large-scale one-dimensional Bi x O y I z nanostructures were fabricated using simple inorganic iodine source. By combing the results of X-ray diffraction and scanning electron microscope, the effect of volume ratios of water and ethanol, concentration of NaOH, and reaction time on the morphologies and crystal phases of Bi x O y I z were elaborated. On the basis of characterizations, a possible process for the growth of Bi5O7I nanobelts was proposed. The optical performances of Bi x O y I z nanostructures were evaluated by ultraviolet-visible-near infrared diffuse reflectance spectra as well as photocatalytic degradation of organic dye and corrosive bacteria. The as-prepared Bi5O7I/Bi2O2CO3/BiOI composite showed excellent photocatalytic activity over malachite green under visible light irradiation, which was deduced closely related to its heterojunction structures.

  4. Constructing a large variety of Dirac-cone materials in the Bi(1-x)Sb(x) thin film system.

    Science.gov (United States)

    Tang, Shuang; Dresselhaus, Mildred S

    2012-12-21

    We theoretically predict that a large variety of Dirac-cone materials can be constructed in Bi(1-x)Sb(x) thin films and we here show how to construct single-, bi- and tri-Dirac-cone materials with various amounts of wave vector anisotropy. These different types of Dirac cones can be of special interest to electronic device design, quantum electrodynamics and other fields.

  5. Flower-like Bi2Se3 nanostructures: Synthesis and their application for the direct electrochemistry of hemoglobin and H2O2 detection

    International Nuclear Information System (INIS)

    Fan Hai; Zhang Shenxiang; Ju Peng; Su Haichao; Ai Shiyun

    2012-01-01

    Highlights: ► Flower-like Bi 2 Se 3 nanostructures were prepared via a hydrothermal technique. ► Bi 2 Se 3 nanostructures significantly improve the direct electron-transfer of Hb. ► The immobilized Hb shows high catalytic activity to the reduction of H 2 O 2 . - Abstract: In this paper, flower-like Bi 2 Se 3 nanostructures consisting of intercrossed nanosheets networks have been synthesized via a facile hydrothermal technique and applied to the protein electrochemistry for the first time. The prepared Bi 2 Se 3 nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The direct electrochemistry of hemoglobin (Hb) has been achieved by immobilizing Hb on the prepared Bi 2 Se 3 nanostructures and Nafion (Nf) modified glassy carbon electrode. Bi 2 Se 3 nanostructures show significant promotion to the direct electron-transfer of Hb. The immobilized Hb retained its biological activity well and shows high catalytic activity to the reduction of hydrogen peroxide (H 2 O 2 ). Under the optimal experimental conditions, the catalytic currents are linear to the concentrations of H 2 O 2 in the range of 2.0 × 10 −6 to 1.0 × 10 −4 M. The corresponding detection limits are 6.3 × 10 −7 M. The prepared flower-like Bi 2 Se 3 nanostructures provide an alternative matrix for protein immobilization and biosensor preparation.

  6. Photoconductivity in BiFeO3 thin films

    Science.gov (United States)

    Basu, S. R.; Martin, L. W.; Chu, Y. H.; Gajek, M.; Ramesh, R.; Rai, R. C.; Xu, X.; Musfeldt, J. L.

    2008-03-01

    The optical properties of epitaxial BiFeO3 thin films have been characterized in the visible range. Variable temperature spectra show an absorption onset near 2.17eV, a direct gap (2.667±0.005eV at 300K), and charge transfer excitations at higher energy. Additionally, we report photoconductivity in BiFeO3 films under illumination from a 100mW /cm2 white light source. A direct correlation is observed between the magnitude of the photoconductivity and postgrowth cooling pressure. Dark conductivities increased by an order of magnitude when comparing films cooled in 760 and 0.1Torr. Large increases in photoconductivity are observed in light.

  7. Large linear magnetoresistance in a new Dirac material BaMnBi2

    International Nuclear Information System (INIS)

    Wang Yi-Yan; Yu Qiao-He; Xia Tian-Long

    2016-01-01

    Dirac semimetal is a class of materials that host Dirac fermions as emergent quasi-particles. Dirac cone-type band structure can bring interesting properties such as quantum linear magnetoresistance and large mobility in the materials. In this paper, we report the synthesis of high quality single crystals of BaMnBi 2 and investigate the transport properties of the samples. BaMnBi 2 is a metal with an antiferromagnetic transition at T N = 288 K. The temperature dependence of magnetization displays different behavior from CaMnBi 2 and SrMnBi 2 , which suggests the possible different magnetic structure of BaMnBi 2 . The Hall data reveals electron-type carriers and a mobility μ (5 K) = 1500 cm 2 /V·s. Angle-dependent magnetoresistance reveals the quasi-two-dimensional (2D) Fermi surface in BaMnBi 2 . A crossover from semiclassical MR ∼ H 2 dependence in low field to MR ∼ H dependence in high field, which is attributed to the quantum limit of Dirac fermions, has been observed in magnetoresistance. Our results indicate the existence of Dirac fermions in BaMnBi 2 . (rapid communication)

  8. Dominance of Plasmonic Resonant Energy Transfer over Direct Electron Transfer in Substantially Enhanced Water Oxidation Activity of BiVO4 by Shape-Controlled Au Nanoparticles.

    Science.gov (United States)

    Lee, Mi Gyoung; Moon, Cheon Woo; Park, Hoonkee; Sohn, Woonbae; Kang, Sung Bum; Lee, Sanghan; Choi, Kyoung Jin; Jang, Ho Won

    2017-10-01

    The performance of plasmonic Au nanostructure/metal oxide heterointerface shows great promise in enhancing photoactivity, due to its ability to confine light to the small volume inside the semiconductor and modify the interfacial electronic band structure. While the shape control of Au nanoparticles (NPs) is crucial for moderate bandgap semiconductors, because plasmonic resonance by interband excitations overlaps above the absorption edge of semiconductors, its critical role in water splitting is still not fully understood. Here, first, the plasmonic effects of shape-controlled Au NPs on bismuth vanadate (BiVO 4 ) are studied, and a largely enhanced photoactivity of BiVO 4 is reported by introducing the octahedral Au NPs. The octahedral Au NP/BiVO 4 achieves 2.4 mA cm -2 at the 1.23 V versus reversible hydrogen electrode, which is the threefold enhancement compared to BiVO 4 . It is the highest value among the previously reported plasmonic Au NPs/BiVO 4 . Improved photoactivity is attributed to the localized surface plasmon resonance; direct electron transfer (DET), plasmonic resonant energy transfer (PRET). The PRET can be stressed over DET when considering the moderate bandgap semiconductor. Enhanced water oxidation induced by the shape-controlled Au NPs is applicable to moderate semiconductors, and shows a systematic study to explore new efficient plasmonic solar water splitting cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Large linear magnetoresistance from neutral defects in Bi$_2$Se$_3$

    OpenAIRE

    Kumar, Devendra; Lakhani, Archana

    2016-01-01

    The chalcogenide Bi$_2$Se$_3$ can attain the three dimensional (3D) Dirac semimetal state under the influence of strain and microstrain. Here we report the presnece of large linear magnetoresistance in such a Bi$_2$Se$_3$ crystal. The magnetoresistance has quadratic form at low fields which crossovers to linear above 4 T. The temperature dependence of magnetoresistance scales with carrier mobility and the crossover field scales with inverse of mobility. Our analysis suggest that the linear ma...

  10. Bi-directional triplexer with butterfly MMI coupler using SU-8 polymer waveguides

    Science.gov (United States)

    Mareš, David; Jeřábek, Vítězslav; Prajzler, Václav

    2015-01-01

    We report about a design of a bi-directional planar optical multiplex/demultiplex filter (triplexer) for the optical part of planar hybrid WDM bi-directional transceiver in fiber-to-the-home (FTTH) PON applications. The triplex lightwave circuit is based on the Epoxy Novolak Resin SU-8 waveguides on the silica-on-silicon substrate with Polymethylmethacrylate cladding layer. The triplexer is comprised of a linear butterfly concept of multimode interference (MMI) coupler separating downstream optical signals of 1490 nm and 1550 nm. For the upstream channel of 1310 nm, an additional directional coupler (DC) is used to add optical signal of 1310 nm propagating in opposite direction. The optical triplexer was designed and optimized using beam propagation method. The insertion losses, crosstalk attenuation, and extinction ratio for all three inputs/outputs were investigated. The intended triplexer was designed using the parameters of the separated DC and MMI filter to approximate the idealized direct connection of both devices.

  11. Large linear magnetoresistance in a new Dirac material BaMnBi2

    Science.gov (United States)

    Wang, Yi-Yan; Yu, Qiao-He; Xia, Tian-Long

    2016-10-01

    Dirac semimetal is a class of materials that host Dirac fermions as emergent quasi-particles. Dirac cone-type band structure can bring interesting properties such as quantum linear magnetoresistance and large mobility in the materials. In this paper, we report the synthesis of high quality single crystals of BaMnBi2 and investigate the transport properties of the samples. BaMnBi2 is a metal with an antiferromagnetic transition at T N = 288 K. The temperature dependence of magnetization displays different behavior from CaMnBi2 and SrMnBi2, which suggests the possible different magnetic structure of BaMnBi2. The Hall data reveals electron-type carriers and a mobility μ(5 K) = 1500 cm2/V·s. Angle-dependent magnetoresistance reveals the quasi-two-dimensional (2D) Fermi surface in BaMnBi2. A crossover from semiclassical MR ˜ H 2 dependence in low field to MR ˜ H dependence in high field, which is attributed to the quantum limit of Dirac fermions, has been observed in magnetoresistance. Our results indicate the existence of Dirac fermions in BaMnBi2. Project supported by the National Natural Science Foundation of China (Grant No. 11574391), the Fundamental Research Funds for the Central Universities, and the Research Funds of Renmin University of China (Grant No. 14XNLQ07).

  12. Large enhancement of Faraday rotation by localized surface plasmon resonance in Au nanoparticles embedded in Bi:YIG film

    International Nuclear Information System (INIS)

    Uchida, H.; Masuda, Y.; Fujikawa, R.; Baryshev, A.V.; Inoue, M.

    2009-01-01

    A large enhancement of the Faraday rotation, which is associated with localized surface plasmon resonance (LSPR), was obtained in a sample with Au nanoparticles embedded in a Bi-substituted yttrium iron garnet (Bi:YIG) film. On a quartz substrate, Au nanoparticles were formed by heating an Au thin film, and a Bi:YIG film was then deposited on them. A sample containing the Au nanoparticles produced by 1000 deg. C heating showed a resonant attenuation with narrower bandwidth in the transmission spectrum than nanoparticles of other samples formed by low-temperature heating. The sharp resonant Faraday rotation angle was 4.4 times larger than the estimated intrinsic Bi:YIG film at the LSPR wavelength; the angular difference was 0.14 deg. A discrepancy in the bandwidth between the transmission attenuation and the resonant Faraday rotation is discussed

  13. On the electronic structure and thermoelectric properties of BiTeBr and BiTeI single crystals and of BiTeI with the addition of BiI3 and CuI

    International Nuclear Information System (INIS)

    Kulbachinskii, Vladimir A.; Kytin, Vladimir G.; Kudryashov, Alexey A.; Kuznetsov, Alexei N.; Shevelkov, Andrei V.

    2012-01-01

    The electronic structures were calculated for BiTeBr and BiTeI using the density-functional theory approach and accounting for the strong spin–orbital interaction. Qualitatively, the band structures for two compounds are similar, showing strong mixing of the p states of all elements in vicinity of the Fermi level, with the band gaps of 0.595 and 0.478 eV for BiTeBr and BiTeI, respectively. The optimized crystal structures show a tendency for the Bi–X (X=Br, I) bond elongation compared to the Bi–Te one. Both compounds are intrinsic n-type semiconductors but display a metallic-like conductivity coupled to rather large thermopower, which is rationalized within the frames of the acoustic phonons scattering model. Because of larger thermopower BiTeBr exhibits a twice higher thermoelectric figure-of-merit near room temperature, ZT=0.17, compared to BiTeI. The addition of 1 mass% of BiI 3 or CuI to BiTeI decreases the mobility of electrons by two orders of magnitude, leading to significantly lower electrical conductivity, but at the same time effectively reduces the thermal conductivity. The prospects of further enhancing the thermoelectric efficiency are briefly discussed. - Graphical abstract: View of the crystal structure of BiTeBr is shown in the figure The optimized crystal structures show a tendency for the Bi–X (X=Br, I) bond elongation compared to the Bi–Te one. The electronic structures were calculated for BiTeBr and BiTeI using the density-functional theory approach and accounting for the strong spin–orbital interaction. Qualitatively, the band structures for two compounds are similar, showing strong mixing of the p states of all elements in vicinity of the Fermi level, with the band gaps of 0.595 and 0.478 eV for BiTeBr and BiTeI, respectively. Both compounds are intrinsic n-type semiconductors but display a metallic-like conductivity coupled to rather large thermopower, which is rationalized within the frames of the acoustic phonons scattering

  14. Evaluation of a bi-directional aluminum honeycomb impact limiter design

    International Nuclear Information System (INIS)

    Doman, M.J.

    1995-01-01

    A 120 Ton shipping cask is being developed for the on-site shipment of dry spent fuel at the Idaho National Engineering Laboratory. Impact limiters were incorporated in the cask design to limit the inertial load of the package and its contents during the hypothetical 9-meter (30-foot) drop accident required by 10CFR71. The design process included: (1) a series of static and dynamic tests to determine the crush characteristics of the bi-directional aluminum honeycomb impact limiter material, (2) the development of an analytical model to predict the cask deceleration force as a function of impact limiter crush, and (3) a series of quarter scale model drop tests to qualify the analytical model. The scale model testing, performed at Sandia National Laboratory in Albuquerque, New Mexico, revealed several design aspects which should be considered in developing bi-directional aluminum honeycomb impact limiters and several other design aspects which should be considered for impact limiter designs in general

  15. Reconfigurable, Bi-Directional Flexfet Level Shifter for Low-Power, Rad-Hard Integration

    Science.gov (United States)

    DeGregorio, Kelly; Wilson, Dale G.

    2009-01-01

    Two prototype Reconfigurable, Bi-directional Flexfet Level Shifters (ReBiLS) have been developed, where one version is a stand-alone component designed to interface between external low voltage and high voltage, and the other version is an embedded integrated circuit (IC) for interface between internal low-voltage logic and external high-voltage components. Targeting stand-alone and embedded circuits separately allows optimization for these distinct applications. Both ReBiLS designs use the commercially available 180-nm Flex fet Independently Double-Gated (IDG) SOI CMOS (silicon on insulator, complementary metal oxide semiconductor) technology. Embedded ReBiLS circuits were integrated with a Reed-Solomon (RS) encoder using CMOS Ultra-Low-Power Radiation Tolerant (CULPRiT) double-gated digital logic circuits. The scope of the project includes: creation of a new high-voltage process, development of ReBiLS circuit designs, and adjustment of the designs to maximize performance through simulation, layout, and manufacture of prototypes. The primary technical objectives were to develop a high-voltage, thick oxide option for the 180-nm Flexfet process, and to develop a stand-alone ReBiLS IC with two 8-channel I/O busses, 1.8 2.5 I/O on the low-voltage pins, 5.0-V-tolerant input and 3.3-V output I/O on the high-voltage pins, and 100-MHz minimum operation with 10-pF external loads. Another objective was to develop an embedded, rad-hard ReBiLS I/O cell with 0.5-V low-voltage operation for interface with core logic, 5.0-V-tolerant input and 3.3-V output I/O pins, and 100-MHz minimum operation with 10- pF external loads. A third objective was to develop a 0.5- V Reed-Solomon Encoder with embedded ReBilS I/O: Transfer the existing CULPRiT RS encoder from a 0.35-micron bulk-CMOS process to the ASI 180-nm Flexfet, rad-hard SOI Process. 0.5-V low-voltage core logic. 5.0-V-tolerant input and 3.3-V output I/O pins. 100-MHz minimum operation with 10- pF external loads. The stand

  16. Shielded high-T{sub c} (Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Lelovic, M.; Eror, N.G. [Department of Materials Science, University of Pittsburgh, Pittsburgh, PA (United States); Balachandran, U.; Prorok, B. [Energy Technology Division, Argonne National Laboratory, Argonne, IL (United States); Selvamanickam, V.; Haldar, P. [Intermagnetics General Corporations, Latham, NY (United States); Talvacchio, J.; Young, R. [Science and Technology Center, Northrop Grumman, Pittsburgh, PA (United States)

    1998-11-01

    A new composite tape was fabricated in which the primary function of the central Ag-sheathed (Bi, Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) filaments was to conduct transport current. A YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (Y-123) thin film was deposited on the top of the Ag-sheathed Bi-2223 tape to shield the applied magnetic field and to protect the central Bi-2223 filaments. The critical current densities of the Y-123-coated, Ag-sheathed Bi-2223 tapes were better than those of an uncoated tape. However, the Y-123 thin film exhibited T{sub c} approx.= 72 K and a broad transition region that shifted the effect to lower temperatures. Furthermore, pole figure measurements showed widely spread a,b planes along the rolling direction, indicating high-angle grain boundaries that diminished the magnitude of the effect. Microstructural observations showed platelike grains of Y-123 with fine growth ledges in the thin film that was heat treated, in contrast with the microstructure of an as-coated thin film that showed large twinned grains. From the processing point of view, the results showed that heat treating Y-123 thin film according to the Bi-2223 tape schedule was compatible with and beneficial for Y-123. These preliminary results may provide a basis for further improvements in processing of long-length Bi-2223 tapes for high-field applications. (author)

  17. Thermoelectric and morphological effects of Peltier pulsing on directional solidification of eutectic Bi-Mn

    Science.gov (United States)

    Silberstein, R. P.; Larson, D. J., Jr.; Dressler, B.

    1984-01-01

    Extensive in situ thermal measurements using Peltier Interface Demarcation (PID) during directional solidification of eutectic Bi/MnBi were carried out. Observations indicate that significant thermal transients occur throughout the sample as a result of the Peltier pulsing. The contributions of the Peltier, Thomson, and Joule heats were separated and studied as a function of pulse intensity and polarity. The Joule and the combined Peltier and Thomson thermal contributions were determined as a function of time during and after the current pulses, close to the solid/liquid interface. Variations of the Bi/MnBi particle morphology clearly reveal the interface shape, changes in interface velocity, meltback, and temporary loss of cooperative growth, as a result of the pulsing.

  18. Imidazoline derivative templated synthesis of broccoli-like Bi2S3 and its electrocatalysis towards the direct electrochemistry of hemoglobin.

    Science.gov (United States)

    Chen, Xiaoqian; Wang, Qingxiang; Wang, Liheng; Gao, Feng; Wang, Wei; Hu, Zhengshui

    2015-04-15

    A broccoli-like bismuth sulfide (bBi2S3) was synthesized via a solvothermal method using a self-made imidazoline derivative of 2-undecyl-1-dithioureido-ethyl-imidazoline as the soft template. The morphology and chemical constitution of the product were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Electrochemical characterization experiments show that the bBi2S3 has the higher specific surface area and standard heterogeneous electron transfer rate constant than the rod-like Bi2S3 (rBi2S3). Hemoglobin (Hb) was then chosen as a protein model to investigate the electrocatalytic property of the synthesized bBi2S3. The results show that Hb entrapped in the composite film of chitosan and bBi2S3 displays an excellent direct electrochemistry, and retains its biocatalytic activity toward the electro-reduction of hydrogen peroxide. The current response in the amperometry shows a linear response to H2O2 concentrations in the range from 0.4 to 4.8µM with high sensitivity (444µAmM(-1)) and low detection limit (0.096µM). The Michaelis-Menten constant (KM(app)) of the fabricated bioelectrode for H2O2 was determined as low as 1µM. These results demonstrate that the synthesized bBi2S3 offers a new path for the immobilization of redox-active protein and the construction of the third-generation biosensors. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Observations of a bi-directional lightning leader producing an M-component

    Science.gov (United States)

    Kotovsky, D. A.; Uman, M. A.; Wilkes, R.; Carvalho, F. L.; Jordan, D. M.

    2017-12-01

    Lightning discharges to ground often exhibit millisecond-scale surges in the continuing currents following return strokes, called M-components. Relatively little is known regarding the source of M-component charge and the mechanisms by which that charge is transferred to ground. In this work, we seek to directly address these questions by presenting correlated high-speed video and Lightning Mapping Array (LMA) observations of a bi-directional leader that resulted in an M-component occurring in a rocket-and-wire triggered lightning flash. The observed leader initiated in the decayed remnants of a positive leader channel that had traversed virgin air approximately 90 msec prior. Three-dimensional locations and speeds of the photographed bi-directional leader and M-component processes are calculated by mapping video images to the observed LMA channel geometry. Both ends of the bi-directional leader exhibited speeds on the order of 2 x106 m sec-1 over 570 meters of the visible channel. Propagation of the luminosity wave from the in-cloud leader to ground ( 8.8 km channel length) exhibited appreciable dispersion, with rise-times (10-90%) increasing from 330 to 410 μsec and pulse-widths (half-maximum) increasing from 380 to 810 μsec - the M-component current pulse measured at ground-level exhibited a rise-time of 290 μsec and a pulse-width of 770 μsec. Group velocities of the luminosity wave have been calculated as a function of frequency, increasing from 2 x107 to 6 x107 m sec-1 over the dominant signal bandwidth (DC to 2 kHz). Additionally, multiple waves of luminosity are observed within the in-cloud channel, indicating nuanced wave phenomena possibly associated with reflection from the end of the leader channel and attachment with the main lightning channel carrying continuing current to ground.

  20. Ultrahigh vacuum STM/STS studies of the Bi-O surface in Bi2Sr2CuOy single crystals

    International Nuclear Information System (INIS)

    Ikeda, Kazuto; Tomeno, Izumi; Takamuku, Kenshi; Yamaguchi, Koji; Itti, Rittaporn; Koshizuka, Naoki

    1992-01-01

    Scanning tunneling microscopic and spectroscopic studies were made on cleaved surfaces of Bi 2 Sr 2 CuO y single crystals using an ultrahigh-vacuum scanning tunneling microscope (UHV-STM). The modulation structures of the Bi-O surface were observed at room temperature with atomic resolution. The tunneling spectra showed electronic gap structures similar to those observed for the Bi-O surface of superconducting Bi-2212 single crystals. This suggests that superconductivity is not directly related to the electronic structure observed in the Bi-O plane. (orig.)

  1. Bi-directional charger for swiss2G - Annual report; Bi-directional charger for swiss2G - Jahresbericht

    Energy Technology Data Exchange (ETDEWEB)

    Schwab, M.; Baumann, P.

    2010-11-15

    This short annual report for 2010 for the Swiss Federal Office of Energy (SFOE) takes a look at a bi-directional charger that can be used in intelligent 'Smart Grid' applications. The idea is based on being able to use electric vehicles as a source of electricity to help meet peak demand for mains electricity. The swiss2G project aims to produce an electric car battery-charger that also functions as an inverter to convert the car's DC battery voltage to mains electricity. The project was started in September 2010. The report describes the aims of the project and reports on initial work done in the areas of safety, switching electronics and AC/DC conversion. National and international co-operation is noted and prospects for further work are discussed.

  2. Development of a bi-directional standing wave linear piezoelectric actuator with four driving feet.

    Science.gov (United States)

    Liu, Yingxiang; Shi, Shengjun; Li, Chunhong; Chen, Weishan; Wang, Liang; Liu, Junkao

    2018-03-01

    A bi-directional standing wave linear piezoelectric ultrasonic actuator with four driving feet is proposed in this work. Two sandwich type transducers operated in longitudinal-bending hybrid modes are set parallelly. The working mode of the transducer is not simple hybrid vibrations of a longitudinal one and a bending one, but a special coupling vibration mode contained both longitudinal and bending components. Two transducers with the same structure and unsymmetrical boundary conditions are set parallelly to accomplish the bi-directional driving: the first transducer can push the runner forward, while the other one produces the backward driving. In the experiments, two voltages with different amplitudes are applied on the two transducers, respectively: the one with higher voltage serves as the actuator, whereas the other one applied with lower voltage is used to reduce the frictional force. The prototype achieves maximum no-load speed and thrust force of 244 mm/s and 9.8 N. This work gives a new idea for the construction of standing wave piezoelectric ultrasonic actuator with bi-directional driving ability. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Large linear magnetoresistance and shubnikov-de hass oscillations in single crystals of YPdBi heusler topological insulators

    KAUST Repository

    Wang, Wenhong; Du, Yin; Xu, Guizhou; Zhang, Xiaoming; Liu, Enke; Liu, Zhongyuan; Shi, Youguo; Chen, Jinglan; Wu, Guangheng; Zhang, Xixiang

    2013-01-01

    We report the observation of a large linear magnetoresistance (MR) and Shubnikov-de Hass (SdH) quantum oscillations in single crystals of YPdBi Heusler topological insulators. Owning to the successfully obtained the high-quality YPdBi single crystals, large non-saturating linear MR of as high as 350% at 5K and over 120% at 300K under a moderate magnetic field of 7T is observed. In addition to the large, field-linear MR, the samples exhibit pronounced SdH quantum oscillations at low temperature. Analysis of the SdH data manifests that the high-mobility bulk electron carriers dominate the magnetotransport and are responsible for the observed large linear MR in YPdBi crystals. These findings imply that the Heusler-based topological insulators have superiorities for investigating the novel quantum transport properties and developing the potential applications.

  4. Large linear magnetoresistance and shubnikov-de hass oscillations in single crystals of YPdBi heusler topological insulators

    KAUST Repository

    Wang, Wenhong

    2013-07-12

    We report the observation of a large linear magnetoresistance (MR) and Shubnikov-de Hass (SdH) quantum oscillations in single crystals of YPdBi Heusler topological insulators. Owning to the successfully obtained the high-quality YPdBi single crystals, large non-saturating linear MR of as high as 350% at 5K and over 120% at 300K under a moderate magnetic field of 7T is observed. In addition to the large, field-linear MR, the samples exhibit pronounced SdH quantum oscillations at low temperature. Analysis of the SdH data manifests that the high-mobility bulk electron carriers dominate the magnetotransport and are responsible for the observed large linear MR in YPdBi crystals. These findings imply that the Heusler-based topological insulators have superiorities for investigating the novel quantum transport properties and developing the potential applications.

  5. Mechanical analysis of non-uniform bi-directional functionally graded intelligent micro-beams using modified couple stress theory

    Science.gov (United States)

    Bakhshi Khaniki, Hossein; Rajasekaran, Sundaramoorthy

    2018-05-01

    This study develops a comprehensive investigation on mechanical behavior of non-uniform bi-directional functionally graded beam sensors in the framework of modified couple stress theory. Material variation is modelled through both length and thickness directions using power-law, sigmoid and exponential functions. Moreover, beam is assumed with linear, exponential and parabolic cross-section variation through the length using power-law and sigmoid varying functions. Using these assumptions, a general model for microbeams is presented and formulated by employing Hamilton’s principle. Governing equations are solved using a mixed finite element method with Lagrangian interpolation technique, Gaussian quadrature method and Wilson’s Lagrangian multiplier method. It is shown that by using bi-directional functionally graded materials in nonuniform microbeams, mechanical behavior of such structures could be affected noticeably and scale parameter has a significant effect in changing the rigidity of nonuniform bi-directional functionally graded beams.

  6. The Role of PTSD in Bi-directional Intimate Partner Violence in Military and Veteran Populations: A Research Review

    Directory of Open Access Journals (Sweden)

    Gabriela Misca

    2017-08-01

    Full Text Available Evidence supporting the higher prevalence of PTSD linked to combat-related trauma in military personnel and veteran populations is well-established. Consequently, much research has explored the effects that combat related trauma and the subsequent PTSD may have on different aspects of relationship functioning and adjustment. In particular, PTSD in military and veterans has been linked with perpetrating intimate partner violence (IPV. New research and theoretical perspectives suggest that in order to respond effectively to IPV, a more accurate understanding of the direction of the violence experienced within each relationship is critical. In both civilian and military populations, research that has examined the direction of IPV's, bi-directional violence have been found to be highly prevalent. Evidence is also emerging as to how these bi-directional violence differ in relation to severity, motivation, physical and psychological consequences and risk factors. Of particular importance within military IPV research is the need to deepen understanding about the role of PTSD in bi-directional IPV not only as a risk factor for perpetration but also as a vulnerability risk factor for victimization, as findings from recent research suggest. This paper provides a timely, critical review of emergent literature to disentangle what is known about bi-directional IPV patterns in military and veteran populations and the roles that military or veterans' PTSD may play within these patterns. Although, this review aimed to identify global research on the topic, the majority of research meeting the inclusion criteria was from US, with only one study identified from outside, from Canada. Strengths and limitations in the extant research are identified. Directions for future research are proposed with a particular focus on the kinds of instruments and designs needed to better capture the complex interplay of PTSD and bi-directional IPV in military populations and

  7. Bi-Directional DC-DC Converter for PHEV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Abas Goodarzi

    2011-01-31

    Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

  8. Bi-directional gene set enrichment and canonical correlation analysis identify key diet-sensitive pathways and biomarkers of metabolic syndrome

    Directory of Open Access Journals (Sweden)

    Gaora Peadar Ó

    2010-10-01

    Full Text Available Abstract Background Currently, a number of bioinformatics methods are available to generate appropriate lists of genes from a microarray experiment. While these lists represent an accurate primary analysis of the data, fewer options exist to contextualise those lists. The development and validation of such methods is crucial to the wider application of microarray technology in the clinical setting. Two key challenges in clinical bioinformatics involve appropriate statistical modelling of dynamic transcriptomic changes, and extraction of clinically relevant meaning from very large datasets. Results Here, we apply an approach to gene set enrichment analysis that allows for detection of bi-directional enrichment within a gene set. Furthermore, we apply canonical correlation analysis and Fisher's exact test, using plasma marker data with known clinical relevance to aid identification of the most important gene and pathway changes in our transcriptomic dataset. After a 28-day dietary intervention with high-CLA beef, a range of plasma markers indicated a marked improvement in the metabolic health of genetically obese mice. Tissue transcriptomic profiles indicated that the effects were most dramatic in liver (1270 genes significantly changed; p Conclusion Bi-directional gene set enrichment analysis more accurately reflects dynamic regulatory behaviour in biochemical pathways, and as such highlighted biologically relevant changes that were not detected using a traditional approach. In such cases where transcriptomic response to treatment is exceptionally large, canonical correlation analysis in conjunction with Fisher's exact test highlights the subset of pathways showing strongest correlation with the clinical markers of interest. In this case, we have identified selenoamino acid metabolism and steroid biosynthesis as key pathways mediating the observed relationship between metabolic health and high-CLA beef. These results indicate that this type of

  9. Transparent organic light-emitting diodes with different bi-directional emission colors using color-conversion capping layers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jonghee, E-mail: jonghee.lee@etri.re.kr [OLED Research Center, Electronics and Telecommunications Research Institute (ETRI), Daejeon 305-700 (Korea, Republic of); Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01062 Dresden (Germany); Koh, Tae-Wook [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Cho, Hyunsu [OLED Research Center, Electronics and Telecommunications Research Institute (ETRI), Daejeon 305-700 (Korea, Republic of); Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Schwab, Tobias [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01062 Dresden (Germany); Lee, Jae-Hyun [Department School of Global Convergence Studies, Hanbat National University, San 16-1, Duckmyoung-dong, Daejeon 305-719 (Korea, Republic of); Hofmann, Simone [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01062 Dresden (Germany); Lee, Jeong-Ik [OLED Research Center, Electronics and Telecommunications Research Institute (ETRI), Daejeon 305-700 (Korea, Republic of); Yoo, Seunghyup [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); and others

    2015-06-15

    We report a study on transparent organic light-emitting diodes (OLEDs) with different bi-directional emission colors, enabled by color-conversion organic capping layers. Starting from a transparent blue OLED with an uncapped Ag top electrode exhibiting an average transmittance of 33.9%, a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped tris-(8-hydroxy-quinolinato)-aluminum (Alq3) capping layer is applied to achieve color-conversion from blue to orange-red on the top side while maintaining almost unchanged device transmittance. This color-conversion capping layer does not only change the color of the top side emission, but also enhances the overall device efficiency due to the optical interaction of the capping layer with the primary blue transparent OLED. Top white emission from the transparent bi-directional OLED exhibits a correlated color temperature around 6000–7000 K, with excellent color stability as evidenced by an extremely small variation in color coordinate of Δ(x,y)=(0.002, 0.002) in the forward luminance range of 100–1000 cd m{sup −2}. At the same time, the blue emission color of bottom side is not influenced by the color conversion capping layer, which finally results in different emission colors of the two opposite sides of our transparent OLEDs. - Highlights: • We report transparent organic light-emitting diodes (OLEDs) with different bi-directional emission colors. • Transparent blue OLED with color-conversion organic capping layers (CCL) shows orange top side emission. • Top white emission exhibits a CCT around 7000 K, with excellent color stability on a driving voltage.

  10. Transparent organic light-emitting diodes with different bi-directional emission colors using color-conversion capping layers

    International Nuclear Information System (INIS)

    Lee, Jonghee; Koh, Tae-Wook; Cho, Hyunsu; Schwab, Tobias; Lee, Jae-Hyun; Hofmann, Simone; Lee, Jeong-Ik; Yoo, Seunghyup

    2015-01-01

    We report a study on transparent organic light-emitting diodes (OLEDs) with different bi-directional emission colors, enabled by color-conversion organic capping layers. Starting from a transparent blue OLED with an uncapped Ag top electrode exhibiting an average transmittance of 33.9%, a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped tris-(8-hydroxy-quinolinato)-aluminum (Alq3) capping layer is applied to achieve color-conversion from blue to orange-red on the top side while maintaining almost unchanged device transmittance. This color-conversion capping layer does not only change the color of the top side emission, but also enhances the overall device efficiency due to the optical interaction of the capping layer with the primary blue transparent OLED. Top white emission from the transparent bi-directional OLED exhibits a correlated color temperature around 6000–7000 K, with excellent color stability as evidenced by an extremely small variation in color coordinate of Δ(x,y)=(0.002, 0.002) in the forward luminance range of 100–1000 cd m −2 . At the same time, the blue emission color of bottom side is not influenced by the color conversion capping layer, which finally results in different emission colors of the two opposite sides of our transparent OLEDs. - Highlights: • We report transparent organic light-emitting diodes (OLEDs) with different bi-directional emission colors. • Transparent blue OLED with color-conversion organic capping layers (CCL) shows orange top side emission. • Top white emission exhibits a CCT around 7000 K, with excellent color stability on a driving voltage

  11. Automatic Detection of Cortical Arousals in Sleep using Bi-direction LSTM Networks

    DEFF Research Database (Denmark)

    Brink-Kjaer, A.; Olesen, Alexander Neergaard; Jespersen, C. A.

    2018-01-01

    ) and chin electromyography (EMG) to compute a probability of arousals through a bi-directional long short-term memory neural network. The study used a dataset of 233 nocturnal PSGs of population-based samples from Wisconsin Sleep Cohort (WSC) and 30 nocturnal PSGs of clinical samples from the Stanford Sleep...

  12. Bi-directional LSTM Recurrent Neural Network for Chinese Word Segmentation

    OpenAIRE

    Yao, Yushi; Huang, Zheng

    2016-01-01

    Recurrent neural network(RNN) has been broadly applied to natural language processing(NLP) problems. This kind of neural network is designed for modeling sequential data and has been testified to be quite efficient in sequential tagging tasks. In this paper, we propose to use bi-directional RNN with long short-term memory(LSTM) units for Chinese word segmentation, which is a crucial preprocess task for modeling Chinese sentences and articles. Classical methods focus on designing and combining...

  13. Bi-Force

    DEFF Research Database (Denmark)

    Sun, Peng; Speicher, Nora K; Röttger, Richard

    2014-01-01

    of pairwise similarities. We first evaluated the power of Bi-Force to solve dedicated bicluster editing problems by comparing Bi-Force with two existing algorithms in the BiCluE software package. We then followed a biclustering evaluation protocol in a recent review paper from Eren et al. (2013) (A...... comparative analysis of biclustering algorithms for gene expressiondata. Brief. Bioinform., 14:279-292.) and compared Bi-Force against eight existing tools: FABIA, QUBIC, Cheng and Church, Plaid, BiMax, Spectral, xMOTIFs and ISA. To this end, a suite of synthetic datasets as well as nine large gene expression...

  14. Bi-directionally protective communication between neurons and astrocytes under ischemia.

    Science.gov (United States)

    Wu, Xiao-Mei; Qian, Christopher; Zhou, Yu-Fu; Yan, Yick-Chun; Luo, Qian-Qian; Yung, Wing-Ho; Zhang, Fa-Li; Jiang, Li-Rong; Qian, Zhong Ming; Ke, Ya

    2017-10-01

    The extensive existing knowledge on bi-directional communication between astrocytes and neurons led us to hypothesize that not only ischemia-preconditioned (IP) astrocytes can protect neurons but also IP neurons protect astrocytes from lethal ischemic injury. Here, we demonstrated for the first time that neurons have a significant role in protecting astrocytes from ischemic injury. The cultured medium from IP neurons (IPcNCM) induced a remarkable reduction in LDH and an increase in cell viability in ischemic astrocytes in vitro. Selective neuronal loss by kainic acid injection induced a significant increase in apoptotic astrocyte numbers in the brain of ischemic rats in vivo. Furthermore, TUNEL analysis, DNA ladder assay, and the measurements of ROS, GSH, pro- and anti-apoptotic factors, anti-oxidant enzymes and signal molecules in vitro and/or in vivo demonstrated that IP neurons protect astrocytes by an EPO-mediated inhibition of pro-apoptotic signals, activation of anti-apoptotic proteins via the P13K/ERK/STAT5 pathways and activation of anti-oxidant proteins via up-regulation of anti-oxidant enzymes. We demonstrated the existence of astro-protection by IP neurons under ischemia and proposed that the bi-directionally protective communications between cells might be a common activity in the brain or peripheral organs under most if not all pathological conditions. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  15. Bi-directionally protective communication between neurons and astrocytes under ischemia

    Directory of Open Access Journals (Sweden)

    Xiao-Mei Wu

    2017-10-01

    Full Text Available The extensive existing knowledge on bi-directional communication between astrocytes and neurons led us to hypothesize that not only ischemia-preconditioned (IP astrocytes can protect neurons but also IP neurons protect astrocytes from lethal ischemic injury. Here, we demonstrated for the first time that neurons have a significant role in protecting astrocytes from ischemic injury. The cultured medium from IP neurons (IPcNCM induced a remarkable reduction in LDH and an increase in cell viability in ischemic astrocytes in vitro. Selective neuronal loss by kainic acid injection induced a significant increase in apoptotic astrocyte numbers in the brain of ischemic rats in vivo. Furthermore, TUNEL analysis, DNA ladder assay, and the measurements of ROS, GSH, pro- and anti-apoptotic factors, anti-oxidant enzymes and signal molecules in vitro and/or in vivo demonstrated that IP neurons protect astrocytes by an EPO-mediated inhibition of pro-apoptotic signals, activation of anti-apoptotic proteins via the P13K/ERK/STAT5 pathways and activation of anti-oxidant proteins via up-regulation of anti-oxidant enzymes. We demonstrated the existence of astro-protection by IP neurons under ischemia and proposed that the bi-directionally protective communications between cells might be a common activity in the brain or peripheral organs under most if not all pathological conditions.

  16. Dynamics of a minimal consumer network with bi-directional influence

    Science.gov (United States)

    Ekaterinchuk, Ekaterina; Jungeilges, Jochen; Ryazanova, Tatyana; Sushko, Iryna

    2018-05-01

    We study the dynamics of a model of interdependent consumer behavior defined by a family of two-dimensional noninvertible maps. This family belongs to a class of coupled logistic maps with different nonlinearity parameters and coupling terms that depend on one variable only. In our companion paper we considered the case of independent consumers as well as the case of uni-directionally connected consumers. The present paper aims at describing the dynamics in the case of a bi-directional connection. In particular, we investigate the bifurcation structure of the parameter plane associated with the strength of coupling between the consumers, focusing on the mechanisms of qualitative transformations of coexisting attractors and their basins of attraction.

  17. Bi-directional series-parallel elastic actuator and overlap of the actuation layers.

    Science.gov (United States)

    Furnémont, Raphaël; Mathijssen, Glenn; Verstraten, Tom; Lefeber, Dirk; Vanderborght, Bram

    2016-01-27

    Several robotics applications require high torque-to-weight ratio and energy efficient actuators. Progress in that direction was made by introducing compliant elements into the actuation. A large variety of actuators were developed such as series elastic actuators (SEAs), variable stiffness actuators and parallel elastic actuators (PEAs). SEAs can reduce the peak power while PEAs can reduce the torque requirement on the motor. Nonetheless, these actuators still cannot meet performances close to humans. To combine both advantages, the series parallel elastic actuator (SPEA) was developed. The principle is inspired from biological muscles. Muscles are composed of motor units, placed in parallel, which are variably recruited as the required effort increases. This biological principle is exploited in the SPEA, where springs (layers), placed in parallel, can be recruited one by one. This recruitment is performed by an intermittent mechanism. This paper presents the development of a SPEA using the MACCEPA principle with a self-closing mechanism. This actuator can deliver a bi-directional output torque, variable stiffness and reduced friction. The load on the motor can also be reduced, leading to a lower power consumption. The variable recruitment of the parallel springs can also be tuned in order to further decrease the consumption of the actuator for a given task. First, an explanation of the concept and a brief description of the prior work done will be given. Next, the design and the model of one of the layers will be presented. The working principle of the full actuator will then be given. At the end of this paper, experiments showing the electric consumption of the actuator will display the advantage of the SPEA over an equivalent stiff actuator.

  18. Extracting the Evaluations of Stereotypes: Bi-factor Model of the Stereotype Content Structure

    Directory of Open Access Journals (Sweden)

    Pablo Sayans-Jiménez

    2017-10-01

    Full Text Available Stereotype dimensions—competence, morality and sociability—are fundamental to studying the perception of other groups. These dimensions have shown moderate/high positive correlations with each other that do not reflect the theoretical expectations. The explanation for this (e.g., halo effect undervalues the utility of the shared variance identified. In contrast, in this work we propose that this common variance could represent the global evaluation of the perceived group. Bi-factor models are proposed to improve the internal structure and to take advantage of the information representing the shared variance among dimensions. Bi-factor models were compared with first order models and other alternative models in three large samples (300–309 participants. The relationships among the global and specific bi-factor dimensions with a global evaluation dimension (measured through a semantic differential were estimated. The results support the use of bi-factor models rather than first order models (and other alternative models. Bi-factor models also show a greater utility to directly and more easily explore the stereotype content including its evaluative content.

  19. Extracting the Evaluations of Stereotypes: Bi-factor Model of the Stereotype Content Structure.

    Science.gov (United States)

    Sayans-Jiménez, Pablo; Cuadrado, Isabel; Rojas, Antonio J; Barrada, Juan R

    2017-01-01

    Stereotype dimensions-competence, morality and sociability-are fundamental to studying the perception of other groups. These dimensions have shown moderate/high positive correlations with each other that do not reflect the theoretical expectations. The explanation for this (e.g., halo effect) undervalues the utility of the shared variance identified. In contrast, in this work we propose that this common variance could represent the global evaluation of the perceived group. Bi-factor models are proposed to improve the internal structure and to take advantage of the information representing the shared variance among dimensions. Bi-factor models were compared with first order models and other alternative models in three large samples (300-309 participants). The relationships among the global and specific bi-factor dimensions with a global evaluation dimension (measured through a semantic differential) were estimated. The results support the use of bi-factor models rather than first order models (and other alternative models). Bi-factor models also show a greater utility to directly and more easily explore the stereotype content including its evaluative content.

  20. Local variation in Bi crystal sites of epitaxial GaAsBi studied by photoelectron spectroscopy and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Laukkanen, P., E-mail: pekka.laukkanen@utu.fi [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Punkkinen, M.P.J., E-mail: marko.punkkinen@utu.fi [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Lahti, A. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Puustinen, J. [Optoelectronics Research Centre, Tampere University of Technology, FI-33101 Tampere (Finland); Tuominen, M. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Hilska, J. [Optoelectronics Research Centre, Tampere University of Technology, FI-33101 Tampere (Finland); Mäkelä, J.; Dahl, J.; Yasir, M. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Kuzmin, M. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021, Russian Federation (Russian Federation); Osiecki, J.R.; Schulte, K. [The MAX IV laboratory, P. O. Box 118, Lund University, SE-221 00 Lund (Sweden); Guina, M. [Optoelectronics Research Centre, Tampere University of Technology, FI-33101 Tampere (Finland); Kokko, K. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland)

    2017-02-28

    Highlights: • XPS is used to study bulk-like properties of GaAsBi crystals. • Surface effects are removed from XPS signal by an epitaxial AlAs cap film. • Local variation of Bi composition is found. • The result is consistent with photoluminescence and theoretical results. • Ga vacancies and Bi crystallites are suggested to be dominating defects. - Abstract: Epitaxial Bi-containing III–V crystals (III-V{sub 1-x}Bi{sub x}) have attracted increasing interest due to their potential in infrared applications. Atomic-scale characterization and engineering of bulk-like III-V{sub 1-x}Bi{sub x} properties (e.g., Bi incorporation and defect formation) are challenging but relevant to develop applications. Toward that target, we report here that the traditional surface-science measurement of photoelectron spectroscopy (PES) is a potential, non-destructive method to be combined in the studies of bulk-like properties, when surface effects are properly removed. We have investigated epitaxial GaAs{sub 1-x}Bi{sub x} films, capped by epitaxial AlAs layers, with high-resolution photoelectron spectroscopy. The Bi5d core-level spectra of GaAs{sub 1-x}Bi{sub x} together with ab-initio calculations give direct evidence of variation of Bi bonding environment in the lattice sites. The result agrees with photoluminescence (PL) measurement which shows that the studied GaAs{sub 1-x}Bi{sub x} films include local areas with higher Bi content, which contribute to PL but do not readily appear in x-ray diffraction (XRD). The measured and calculated Bi core-level shifts show also that Ga vacancies and Bi clusters are dominant defects.

  1. The Bi-Directional Prediction of Carbon Fiber Production Using a Combination of Improved Particle Swarm Optimization and Support Vector Machine.

    Science.gov (United States)

    Xiao, Chuncai; Hao, Kuangrong; Ding, Yongsheng

    2014-12-30

    This paper creates a bi-directional prediction model to predict the performance of carbon fiber and the productive parameters based on a support vector machine (SVM) and improved particle swarm optimization (IPSO) algorithm (SVM-IPSO). In the SVM, it is crucial to select the parameters that have an important impact on the performance of prediction. The IPSO is proposed to optimize them, and then the SVM-IPSO model is applied to the bi-directional prediction of carbon fiber production. The predictive accuracy of SVM is mainly dependent on its parameters, and IPSO is thus exploited to seek the optimal parameters for SVM in order to improve its prediction capability. Inspired by a cell communication mechanism, we propose IPSO by incorporating information of the global best solution into the search strategy to improve exploitation, and we employ IPSO to establish the bi-directional prediction model: in the direction of the forward prediction, we consider productive parameters as input and property indexes as output; in the direction of the backward prediction, we consider property indexes as input and productive parameters as output, and in this case, the model becomes a scheme design for novel style carbon fibers. The results from a set of the experimental data show that the proposed model can outperform the radial basis function neural network (RNN), the basic particle swarm optimization (PSO) method and the hybrid approach of genetic algorithm and improved particle swarm optimization (GA-IPSO) method in most of the experiments. In other words, simulation results demonstrate the effectiveness and advantages of the SVM-IPSO model in dealing with the problem of forecasting.

  2. The Bi-Directional Prediction of Carbon Fiber Production Using a Combination of Improved Particle Swarm Optimization and Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Chuncai Xiao

    2014-12-01

    Full Text Available This paper creates a bi-directional prediction model to predict the performance of carbon fiber and the productive parameters based on a support vector machine (SVM and improved particle swarm optimization (IPSO algorithm (SVM-IPSO. In the SVM, it is crucial to select the parameters that have an important impact on the performance of prediction. The IPSO is proposed to optimize them, and then the SVM-IPSO model is applied to the bi-directional prediction of carbon fiber production. The predictive accuracy of SVM is mainly dependent on its parameters, and IPSO is thus exploited to seek the optimal parameters for SVM in order to improve its prediction capability. Inspired by a cell communication mechanism, we propose IPSO by incorporating information of the global best solution into the search strategy to improve exploitation, and we employ IPSO to establish the bi-directional prediction model: in the direction of the forward prediction, we consider productive parameters as input and property indexes as output; in the direction of the backward prediction, we consider property indexes as input and productive parameters as output, and in this case, the model becomes a scheme design for novel style carbon fibers. The results from a set of the experimental data show that the proposed model can outperform the radial basis function neural network (RNN, the basic particle swarm optimization (PSO method and the hybrid approach of genetic algorithm and improved particle swarm optimization (GA-IPSO method in most of the experiments. In other words, simulation results demonstrate the effectiveness and advantages of the SVM-IPSO model in dealing with the problem of forecasting.

  3. High electron mobility and large magnetoresistance in the half-Heusler semimetal LuPtBi

    KAUST Repository

    Hou, Zhipeng

    2015-12-18

    Materials with high carrier mobility showing large magnetoresistance (MR) have recently received much attention because of potential applications in future high-performance magnetoelectric devices. Here, we report on an electron-hole-compensated half-Heusler semimetal LuPtBi that exhibits an extremely high electron mobility of up to 79000cm2/Vs with a nonsaturating positive MR as large as 3200% at 2 K. Remarkably, the mobility at 300 K is found to exceed 10500cm2/Vs, which is among the highest values reported in three-dimensional bulk materials thus far. The clean Shubnikov–de Haas quantum oscillation observed at low temperatures and the first-principles calculations together indicate that the high electron mobility is due to a rather small effective carrier mass caused by the distinctive band structure of the crystal. Our findings provide a different approach for finding large, high-mobility MR materials by designing an appropriate Fermi surface topology starting from simple electron-hole-compensated semimetals.

  4. Three-port bi-directional converter for electric vehicles: focus on high-frequency coaxial transformer

    NARCIS (Netherlands)

    Waltrich, G.; Duarte, J.L.; Hendrix, M.A.M.; Paulides, J.J.H.

    2010-01-01

    A bi-directional multi-port converter can accommodate various energy storages and sources. Therefore, a multiport converter will be a good candidate for application as a future universal converter for (hybrid) electrical vehicles or local distribution systems. The main design challenge of the

  5. Coordinated Operation of the Electricity and Natural Gas Systems with Bi-directional Energy Conversion

    DEFF Research Database (Denmark)

    Zeng, Qing; Zhang, Baohua; Fang, Jiakun

    2017-01-01

    A coordinated operation of the natural gas and electricity network with bi-directional energy conversion is expected to accommodate high penetration levels of renewables. This work focuses on the unified optimal operation of the integrated natural gas and electricity system considering the network...

  6. Bi-directional reflectance distribution function of a tungsten block for ITER divertor

    International Nuclear Information System (INIS)

    Iwamae, Atsushi; Ogawa, Hiroaki; Sugie, Tatsuo; Kusama, Yoshinori

    2012-02-01

    In order to investigate reflection properties on plasma-facing material in ITER, the bi-directional reflectance distribution function (BRDF) of a tungsten block sample has been measured. On the machining surface of the block, one-directional machining lines are engraved. Two laser diodes λ652 nm and λ473 nm were used to simulate H α and H β emissions, respectively. The reflected light is affected by the machining surface. The reflected light traces an arc when the incident light is injected in the parallel direction to the engraved line. On the other hand the reflected light traces a line shape when the incident light is injected in the perpendicular direction to the engraved lines. Ray tracing simulation qualitatively explains the experimental results. (author)

  7. Imaging Formation Algorithm of the Ground and Space-Borne Hybrid BiSAR Based on Parameters Estimation from Direct Signal

    Directory of Open Access Journals (Sweden)

    Qingjun Zhang

    2014-01-01

    Full Text Available This paper proposes a novel image formation algorithm for the bistatic synthetic aperture radar (BiSAR with the configuration of a noncooperative transmitter and a stationary receiver in which the traditional imaging algorithm failed because the necessary imaging parameters cannot be estimated from the limited information from the noncooperative data provider. In the new algorithm, the essential parameters for imaging, such as squint angle, Doppler centroid, and Doppler chirp-rate, will be estimated by full exploration of the recorded direct signal (direct signal is the echo from satellite to stationary receiver directly from the transmitter. The Doppler chirp-rate is retrieved by modeling the peak phase of direct signal as a quadratic polynomial. The Doppler centroid frequency and the squint angle can be derived from the image contrast optimization. Then the range focusing, the range cell migration correction (RCMC, and the azimuth focusing are implemented by secondary range compression (SRC and the range cell migration, respectively. At last, the proposed algorithm is validated by imaging of the BiSAR experiment configured with china YAOGAN 10 SAR as the transmitter and the receiver platform located on a building at a height of 109 m in Jiangsu province. The experiment image with geometric correction shows good accordance with local Google images.

  8. Microwave-assisted hydrothermal synthesis of Bi2S3 nanorods in flower-shaped bundles

    International Nuclear Information System (INIS)

    Thongtem, Titipun; Pilapong, Chalermchai; Kavinchan, Jutarat; Phuruangrat, Anukorn; Thongtem, Somchai

    2010-01-01

    Bi 2 S 3 nanorods in flower-shaped bundles were successfully synthesized from the decomposition of Bi-thiourea complexes under the microwave-assisted hydrothermal process. X-ray powder diffraction (XRD) patterns and field emission scanning electron microscopy (FE-SEM) show that Bi 2 S 3 has the orthorhombic phase and appears as nanorods in flower-shaped bundles. A transmission electron microscopic (TEM) study reveals the independent single Bi 2 S 3 nanorods with their growth along the [0 0 1] direction. A possible formation mechanism of Bi 2 S 3 nanorods in flower-shaped bundles is also proposed and discussed. Their UV-vis spectrum shows the absorbance at 596 nm, with its direct energy band gap of 1.82 eV.

  9. Spatial profile of thermoelectric effects during Peltier pulsing in Bi and Bi/MnBi eutectic

    Science.gov (United States)

    Silberstein, R. P.; Larson, D. J., Jr.

    1987-01-01

    The spatial profile of the thermal transients that occur during and following the current pulsing associated with Peltier Interface Demarcation during directional solidification is studied. Results for pure Bi are presented in detail and compared with corresponding results for the Bi/MnBi eutectic. Significant thermal transients occur throughout the sample that can be accounted for by the Peltier effect, the Thomson effect, and Joule heating. These effects are separated and their behavior is studied as a function of time, current density, and position with respect to the solid/liquid interface.

  10. Tolerance of topological surface state towards adsorbed magnetic moments: Fe on Bi{sub 2}Te{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, Markus; Marchenko, Dmitry; Sanchez-Barriga, Jaime; Varykhalov, Andrei; Rader, Oliver [Helmholtz-Zentrum fuer Materialien und Energie, Berlin (Germany); Volykhov, Andrei; Yashina, Lada [Moscow State University, Moskau, Russland (Russian Federation)

    2011-07-01

    Topological surface states on Bi{sub 2}Se{sub 3} and Bi{sub 2}Te{sub 3} are protected by time reversal symmetry. Magnetic fields break time-reversal symmetry, and they have been used in two-dimensional spin quantum-Hall systems to destroy the topological edge states. Another possibility is to introduce magnetic moments. This has been done by substitution of Mn and Fe into the bulk. For Fe a small gap of 44meV was created, however, at very large amounts (12%). In this work, we deposit Fe directly onto the surface where the topological surface state is localized. We show for coverages of 0.25 and 1 ML Fe that the Dirac point remains intact and no gap appears. Core level spectroscopy of Bi and Te states gives insight into the interaction between substrate and adatoms. In addition, extra surface states appear at the Fermi energy which show a large Rashba-type spin-orbit splitting. The orientation of the spin of both, the topological as well as the Rashba-type split surface states is analysed.

  11. TiO2/Bi2(BDC)3/BiOCl nanoparticles decorated ultrathin nanosheets with excellent photocatalytic reaction activity and selectivity

    International Nuclear Information System (INIS)

    Zhou, Shu-Mei; Ma, De-Kun; Cai, Ping; Chen, Wei; Huang, Shao-Ming

    2014-01-01

    Graphical abstract: TiO 2 /Bi 2 (BDC) 3 /BiOCl nanoparticles decorated ultrathin nanosheets showed excellent photocatalytic reaction activity and selectivity. - Highlights: • TiO 2 /Bi 2 (BDC) 3 /BiOCl nanoparticles decorated ultrathin nanosheets were synthesized through a facile hydrothermal process. • The products showed excellent photocatalytic activities for the degradation of various dyes. • The photocatalytic activities of the composite materials could be easily adjusted through tuning the content of TiO 2 . • TiO 2 /Bi 2 (BDC) 3 /BiOCl displayed obvious photocatalytic selectivity in mixed dyes systems of rhodamine B and eosin Y. - Abstract: Photocatalysts with excellent photocatalytic reaction activity and ideal selectivity are highly desirable for pollutants clearance and purification of targeted organics from a mixture. Continued efforts toward the goal, we here present a facile hydrothermal route to synthesize TiO 2 /Bi-benzenedicarboxylate/BiOCl nanoparticles decorated ultrathin nanosheets with a thickness less than 5 nm on a large scale. The as-synthesized products showed excellent photocatalytic activities for the degradation of various dyes such as rhodamine B, eosin Y and methylene blue in aqueous solution under visible light irradiation. The photocatalytic activities of TiO 2 /Bi-benzenedicarboxylate/BiOCl nanocomposites for the degradation of rhodamine B and eosin Y could be adjusted through tuning the content of TiO 2 . With increasing the amount of TiO 2 , the composites showed declining photocatalytic activities in decomposing of rhodamine B while on the contrary they displayed enhanced photocatalytic activities in decomposing of eosin Y. Interestingly, TiO 2 /Bi-benzenedicarboxylate/BiOCl composite nanosheets showed obvious photocatalytic selectivity in a mixed dyes system. The photocatalytic reaction and selectivity mechanisms of the nanocomposites for the degradation of the dyes were discussed on the basis of experimental results. The

  12. Bi-directional exchange of membrane components occurs during co-culture of mesenchymal stem cells and nucleus pulposus cells.

    Science.gov (United States)

    Strassburg, Sandra; Hodson, Nigel W; Hill, Patrick I; Richardson, Stephen M; Hoyland, Judith A

    2012-01-01

    Mesenchymal stem cell (MSC)-based therapies have been proposed as novel treatments for intervertebral disc (IVD) degeneration. We have previously demonstrated that when MSCs are co-cultured with nucleus pulposus (NP) cells with direct cell-cell contact, they differentiate along the NP lineage and simultaneously stimulate the degenerate NP cell population to regain a normal (non-degenerate) phenotype, an effect which requires cell-cell communication. However, the mechanisms by which NP cells and MSCs interact in this system are currently unclear. Thus, in this study we investigated a range of potential mechanisms for exchange of cellular components or information that may direct these changes, including cell fusion, gap-junctional communication and exchange of membrane components by direct transfer or via microvesicle formation. Flow cytometry of fluorescently labeled MSCs and NP cells revealed evidence of some cell fusion and formation of gapjunctions, although at the three timepoints studied these phenomena were detectable only in a small proportion of cells. While these mechanisms may play a role in cell-cell communication, the data suggests they are not the predominant mechanism of interaction. However, flow cytometry of fluorescently dual-labeled cells showed that extensive bi-directional transfer of membrane components is operational during direct co-culture of MSCs and NP cells. Furthermore, there was also evidence for secretion and internalization of membrane-bound microvesicles by both cell types. Thus, this study highlights bi-directional intercellular transfer of membrane components as a possible mechanism of cellular communication between MSC and NP cells.

  13. MicroRNAs let-7b/i suppress human glioma cell invasion and migration by targeting IKBKE directly

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Yuan; Hao, Shaobo [Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052 (China); Laboratory of Neuro-Oncology, Tianjin Neurological Institute, Tianjin 300052 (China); Key Laboratory of Neurotrauma, Variation and Regeneration, Ministry of Education and Tianjin Municipal Government (China); Ye, Minhua [Department of Neurosurgery, Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi Province 330006 (China); Zhang, Anling [Laboratory of Neuro-Oncology, Tianjin Neurological Institute, Tianjin 300052 (China); Key Laboratory of Neurotrauma, Variation and Regeneration, Ministry of Education and Tianjin Municipal Government (China); Nan, Yang [Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052 (China); Wang, Guangxiu; Jia, Zhifan [Laboratory of Neuro-Oncology, Tianjin Neurological Institute, Tianjin 300052 (China); Key Laboratory of Neurotrauma, Variation and Regeneration, Ministry of Education and Tianjin Municipal Government (China); Yu, Kai; Guo, Lianmei [Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052 (China); Pu, Peiyu [Laboratory of Neuro-Oncology, Tianjin Neurological Institute, Tianjin 300052 (China); Key Laboratory of Neurotrauma, Variation and Regeneration, Ministry of Education and Tianjin Municipal Government (China); Huang, Qiang, E-mail: huangqiang209@163.com [Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052 (China); Zhong, Yue, E-mail: zhongyue2457@sina.com [Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052 (China)

    2015-03-06

    We demonstrated that IKBKE is overexpressed in human gliomas and that the downregulation of IKBKE markedly inhibits the proliferative and invasive abilities of glioma cells, which is consistent with the results reported by several different research groups. Therefore, IKBKE represents a promising therapeutic target for the treatment of glioma. In the present study, we verified that the microRNAs let-7b and let-7i target IKBKE through luciferase assays and found that let-7b/i mimics can knock down IKBKE and upregulate E-cadherin through western blot analysis. Moreover, the expression levels of let-7b/i were significantly lower in glioma cell lines than that in normal brain tissues, as determined by quantitative real-time PCR. Furthermore, let-7b/i inhibit the invasion and migration of glioma cells, as determined through wound healing and Transwell assays. The above-mentioned data suggest that let-7b/i inhibit the invasive ability of glioma cells by directly downregulating IKBKE and indirectly upregulating E-cadherin. - Highlights: • Let-7b and let-7i are downregulated in glioma cell lines. • IKBKE is a target gene of let-7b/i. • Let-7b/i inhibit the invasion and migration of glioma cells. • Let-7b/i upregulate E-cadherin by downregulating IKBKE.

  14. MicroRNAs let-7b/i suppress human glioma cell invasion and migration by targeting IKBKE directly

    International Nuclear Information System (INIS)

    Tian, Yuan; Hao, Shaobo; Ye, Minhua; Zhang, Anling; Nan, Yang; Wang, Guangxiu; Jia, Zhifan; Yu, Kai; Guo, Lianmei; Pu, Peiyu; Huang, Qiang; Zhong, Yue

    2015-01-01

    We demonstrated that IKBKE is overexpressed in human gliomas and that the downregulation of IKBKE markedly inhibits the proliferative and invasive abilities of glioma cells, which is consistent with the results reported by several different research groups. Therefore, IKBKE represents a promising therapeutic target for the treatment of glioma. In the present study, we verified that the microRNAs let-7b and let-7i target IKBKE through luciferase assays and found that let-7b/i mimics can knock down IKBKE and upregulate E-cadherin through western blot analysis. Moreover, the expression levels of let-7b/i were significantly lower in glioma cell lines than that in normal brain tissues, as determined by quantitative real-time PCR. Furthermore, let-7b/i inhibit the invasion and migration of glioma cells, as determined through wound healing and Transwell assays. The above-mentioned data suggest that let-7b/i inhibit the invasive ability of glioma cells by directly downregulating IKBKE and indirectly upregulating E-cadherin. - Highlights: • Let-7b and let-7i are downregulated in glioma cell lines. • IKBKE is a target gene of let-7b/i. • Let-7b/i inhibit the invasion and migration of glioma cells. • Let-7b/i upregulate E-cadherin by downregulating IKBKE

  15. Technologies for hydrogen production based on direct contact of gaseous hydrocarbons and evaporated water with Molten Pb or Pb-Bi

    International Nuclear Information System (INIS)

    Gulevich, A. V.; Martynov, P. N.; Gulevsky, V. A.; Ulyanov, V. V.

    2007-01-01

    hydrogen (at t≥500 degree C). A valuable product is formed in this process - powdery carbon readily removable from the reaction zone owing to a large density difference of carbon vs. liquid metal. 3. The oxidation conversion of hydrocarbons (at t≥500 degree C). Hydrogen and CO 2 , hydrogen and synthetic gas (H 2 and CO mixture) can be obtained as end products. This process develops more effectively compared to the traditional vapor conversion. The increase of conversion effectiveness is caused by the new processes not employed before: hydrocarbon oxidation by oxides present in the reaction zone as dissolved in the melt and in solid phase; co-oxidation of hydrocarbons by evaporated water and HLMC oxides. As a result of enhanced effectiveness of oxidation conversion, the conditions for its fulfillment can be considerably simplified - the working pressure, as well as the process temperature can be decreased to the level at which it becomes possible to use structural materials, equipment, and appropriate measures for the employment of technology with coolants that have been developed and substantiated for operation in circuits with Pb and Pb-Bi coolants. The dimensions of 'direct contact' devices for hydrogen production can be very small. Therefore, they can find application both in large-scale hydrogen production, and in small-size (remote) sources of hydrogen

  16. Synthesis of chemically bonded BiOCl@Bi{sub 2}WO{sub 6} microspheres with exposed (0 2 0) Bi{sub 2}WO{sub 6} facets and their enhanced photocatalytic activities under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yongchao [Qingdao Agricultural University, Qingdao 266109 (China); Chen, Zhiwei [School of Life Sciences, Shandong University of Technology, Zibo 255049 (China); Qu, Dan [Qingdao Agricultural University, Qingdao 266109 (China); Shi, Jinsheng, E-mail: jsshiqn@aliyun.com [Qingdao Agricultural University, Qingdao 266109 (China)

    2016-01-15

    Graphical abstract: - Highlights: • BiOCl@Bi{sub 2}WO{sub 6} composites were prepared via a controlled anion exchange method. • The shell of composites was composed of Bi{sub 2}WO{sub 6} sheets with exposed (0 2 0) facets. • The BiOCl@Bi{sub 2}WO{sub 6} composites showed efficient photocatalytic activity. • A possible photocatalytic degradation mechanism is proposed. - Abstract: Bi{sub 2}WO{sub 6} photocatalysts has been extensively studied for its photocatalytic activity. However, few works have been conducted on hierarchical Bi{sub 2}WO{sub 6} composite photocatalysts with specifically exposed facets. In this work, we report a facile method to synthesize BiOCl@Bi{sub 2}WO{sub 6} hierarchical composite microspheres. Bi{sub 2}WO{sub 6} nanosheets with specifically exposed (0 2 0) facet were directly formed on the surface of BiOCl precursor microspheres via a controlled anion exchange route between BiOCl and Na{sub 2}WO{sub 4}. The visible-light photocatalytic activity of the BiOCl@Bi{sub 2}WO{sub 6} heterojunction with exposed (0 2 0) facets (denoted as BiOCl@Bi{sub 2}WO{sub 6}) was investigated by degradation of Rhodamine B (RhB) and ciprofloxacin (CIP) aqueous solution under visible light irradiation. The experimental results indicated that the BiOCl@Bi{sub 2}WO{sub 6} composite microsphere with intimate interfacial contacts exhibited improved efficiency for RhB photodegradation in comparison with pure BiOCl and Bi{sub 2}WO{sub 6}. The BiOCl@Bi{sub 2}WO{sub 6} composite microsphere also shows high photocatalytic activity for degradation of CIP under visible light irradiation. The enhanced photocatalytic performance of BiOCl@Bi{sub 2}WO{sub 6}-020 hierarchical microspheres can be ascribed to the improved visible light harvesting ability, high charge separation and transfer. This work will make significant contributions toward the exploration of novel heterostructures with high potential in photocatalytic applications.

  17. Bi-Polaron Condensation in High Tc Superconductors

    International Nuclear Information System (INIS)

    Ranninger, J.

    1995-01-01

    On the basis of optical measurements-, photoemission-, EXAFS- and neutron scattering-experiments we conclude that itinerant valence electrons coexist with localized bi-polarons.Entering the metallic phase upon chemical doping, a charge transfer between the two electronic subsystems is triggered off. We show that as the temperature is lowered towards Tc this process leads to a delocalization of bi-polarons due to a precursor effect of superfluidity of those bi-polarons. Upon entering the superconducting phase, these bipolarons ultimately condense into a superfluid state which is expected to largely determine the superconducting properties of high Tc materials. (authors)

  18. Light alkane (mixed feed selective dehydrogenation using bi-metallic zeolite supported catalyst

    Directory of Open Access Journals (Sweden)

    Zeeshan Nawaz

    2009-12-01

    Full Text Available Light alkanes are the important intermediates of many refinery processes and their catalytic dehydrogenation gives corresponding alkenes. The aim behind this experimentation is to investigate reaction behavior of mixed alkanes during direct catalytic dehydrogenation and emphasis has been given to enhance propene. Bi-metallic zeolite supported catalyst Pt-Sn/ZSM-5 was prepared by sequentional impregnation method and characterized by BET, EDS and XRD. Direct dehydrogenation reaction is highly endothermic and its conversion is thermodynamically limited. Results showed that the increase in temperature increases the conversion to some extent but there is no overall effect on selectivity of propene. Increase in time-on-stream (TOS remarkably improves propene selectivity at the expense of lower conversion. The performances of bi-metallic zeolite based catalyst largely affected by coke deposition. The presence of butane and ethane adversely affected propane conversion. Optimum propene selectivity is about 48 %, obtained at 600 oC and time-on-stream 10 h.

  19. Comparative Study on Uni- and Bi-Directional Fluid Structure Coupling of Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Mesfin Belayneh Ageze

    2017-09-01

    Full Text Available The current trends of wind turbine blade designs are geared towards a longer and slender blade with high flexibility, exhibiting complex aeroelastic loadings and instability issues, including flutter; in this regard, fluid-structure interaction (FSI plays a significant role. The present article will conduct a comparative study between uni-directional and bi-directional fluid-structural coupling models for a horizontal axis wind turbine. A full-scale, geometric copy of the NREL 5MW blade with simplified material distribution is considered for simulation. Analytical formulations of the governing relations with appropriate approximation are highlighted, including turbulence model, i.e., Shear Stress Transport (SST k-ω. These analytical relations are implemented using Multiphysics package ANSYS employing Fluent module (Computational Fluid Dynamics (CFD-based solver for the fluid domain and Transient Structural module (Finite Element Analysis-based solver for the structural domain. ANSYS system coupling module also is configured to model the two fluid-structure coupling methods. The rated operational condition of the blade for a full cycle rotation is considered as a comparison domain. In the bi-directional coupling model, the structural deformation alters the angle of attack from the designed values, and by extension the flow pattern along the blade span; furthermore, the tip deflection keeps fluctuating whilst it tends to stabilize in the uni-directional coupling model.

  20. Single-stage three-phase AC to DC conversion with isolation and Bi-directional power flow

    NARCIS (Netherlands)

    Vermulst, B.J.D.; Duarte, J.L.; Wijnands, C.G.E.; Lomonova, E.A.

    2014-01-01

    An approach for three-phase AC to DC conversion is proposed, which consists of a single-stage while offering galvanic isolation, soft-switching, bi-directional power flow and a significant reduction of inductive and capacitive energy storage. Two elements enable this approach, namely a neutral

  1. Study on bi-directional pedestrian movement using ant algorithms

    International Nuclear Information System (INIS)

    Gokce, Sibel; Kayacan, Ozhan

    2016-01-01

    A cellular automata model is proposed to simulate bi-directional pedestrian flow. Pedestrian movement is investigated by using ant algorithms. Ants communicate with each other by dropping a chemical, called a pheromone, on the substrate while crawling forward. Similarly, it is considered that oppositely moving pedestrians drop ‘visual pheromones’ on their way and the visual pheromones might cause attractive or repulsive interactions. This pheromenon is introduced into modelling the pedestrians’ walking preference. In this way, the decision-making process of pedestrians will be based on ‘the instinct of following’. At some densities, the relationships of velocity–density and flux–density are analyzed for different evaporation rates of visual pheromones. Lane formation and phase transition are observed for certain evaporation rates of visual pheromones. (paper)

  2. Bi-directional associations between psychological arousal, cortisol, and sleep

    DEFF Research Database (Denmark)

    Garde, Anne Helene; Albertsen, Karen; Persson, Roger

    2012-01-01

    The aim was to elucidate the possible bi-directional relation between daytime psychological arousal, cortisol, and self-reported sleep in a group of healthy employees in active employment. Logbook ratings of sleep (Karolinska Sleep Questionnaire), stress, and energy, as well as positive...... and negative experiences in work and private life, were collected together with salivary cortisol over 3 days (n = 265). Higher bedtime ratings of stress and problems during the day were associated with morning ratings of poor sleep. Poorer morning ratings of sleep were associated with higher ratings of stress...... and problems during the day. The results underpin the possibility that arousal and poor sleep might create a self-reinforcing vicious circle that negatively affects a person's well-being....

  3. Insights into the photocatalytic mechanism of mediator-free direct Z-scheme g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures: A hybrid density functional theory study

    Science.gov (United States)

    Opoku, Francis; Govender, Krishna Kuben; Sittert, Cornelia Gertina Catharina Elizabeth van; Govender, Penny Poomani

    2018-01-01

    Graphite-like carbon nitride (g-C3N4)-based heterostructures have received much attention due to their prominent photocatalytic activity. The g-C3N4/Bi2WO6 and g-C3N4/Bi2MoO6 heterostructures, which follow a typical hetero-junction charge transfer mechanisms show a weak potential for hydrogen evolution and reactive radical generation under visible light irradiation. A mediator-free Z-scheme g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures photocatalyst are designed for the first time using first-principles studies. Moreover, theoretical understanding of the underlying mechanism, the effects of interfacial composition and the role the interface play in the overall photoactivity is still unexplained. The calculated band gap of the heterostructures is reduced compared to the bulk Bi2WO6 and Bi2MoO6. In this study, we systematically calculated energy band structure, optical properties and charge transfer of the g-C3N4/Bi2MoO6(010) and g-C3N4/Bi2WO6(010) heterostructures using the hybrid density functional theory approach. The results show that the charge transfer at the interface of the heterostructures induces a built-in potential, which benefits the separation of photogenerated charge carriers. The g-C3N4/Bi2MoO6(010) heterostructure with more negative adhesion energy (-1.10 eVA-2) is predicted to have a better adsorptive ability and can form more easily compared to the g-C3N4/Bi2WO6(010) interface (-1.16 eVA-2). Therefore, our results show that the g-C3N4 interaction with Bi2MoO6 is stronger than Bi2WO6, which is also verified by the smaller vertical separation (3.25 Å) between Bi2MoO6 and g-C3N4 compared to the g-C3N4/Bi2WO6(010) interface (3.36 Å). The optical absorption verifies that these proposed Z-scheme heterostructures are excellent visible light harvesting semiconductor photocatalyst materials. This enhancement is ascribed to the role of g-C3N4 monolayer as an electron acceptor and the direct Z-scheme charge carrier transfer at the interface of

  4. Microstructure Of MnBi/Bi Eutectic Alloy

    Science.gov (United States)

    Wilcox, William R.; Eisa, G. F.; Baskaran, B.; Richardson, Donald C.

    1988-01-01

    Collection of three reports describes studies of directional solidification of MnBi/Bi eutectic alloy. Two of the reports, "Influence of Convection on Lamellar Spacing of Eutectics" and "Influence of Convection on Eutectic Microstructure," establish theoretical foundation for remaining document. Reports seek to quantify effect of convection on concentration field of growing lamellar eutectic. Remaining report, "Study of Eutectic Formation," begins by continuing theoretical developments. New technique under development by one of the authors helps to reveal three-dimensional microstructures of alloys.

  5. An Observational Approach to Testing Bi-Directional Parent-Child Interactions as Influential to Child Eating and Weight

    Science.gov (United States)

    Demir, Defne; Skouteris, Helen; Dell'Aquila, Daniela; Aksan, Nazan; McCabe, Marita P.; Ricciardelli, Lina A.; Milgrom, Jeannette; Baur, Louise A.

    2012-01-01

    Obesity among children has been on the rise globally for the past few decades. Previous research has centred mainly on self/parent-reported measures examining only uni-directional parental feeding styles and practices. Recent discussions in the literature have raised the importance of bi-directional parent-child interactions in influencing…

  6. Aplikasi Migrasi Database dan Replikasi Bi-Directional

    Directory of Open Access Journals (Sweden)

    Michael Yoseph Ricky

    2011-12-01

    Full Text Available This study aims to analyze and design a migration and replication configurations in an enterprise using several methods such as literary study and direc survey to the company; analysis on hangar systems, process migration and replication as well as existing problems; and a prototype design for migration process implementated with Oracle SQL Developer and replication process implementated with Oracle GoldenGate. The study resluts ini a prototype for migration and replication configuration processes using Oracle's Golden Gate which can produce two sets of identical data for backup and recovery. Also a simple tool is designed to assist active-active replication process as well as active-passive one. The migration process from MySQL database to Oracle database using Oracle GoldenGate can not be done because GoldenGate Oracle has bugs related to the binary log, so database migration is done using Oracle SQL Developer. However, bi-directional replication between Oracle database using Oracle GoldenGate can ensure data availability and reduce the workload of primary database. 

  7. Large critical current density improvement in Bi-2212 wires through the groove-rolling process

    International Nuclear Information System (INIS)

    Malagoli, A; Bernini, C; Braccini, V; Romano, G; Putti, M; Chaud, X; Debray, F

    2013-01-01

    Recently there has been a growing interest in Bi-2212 superconductor round wire for high magnetic field use despite the fact that an increase of the critical current is still needed to boost its successful use in such applications. Recent studies have demonstrated that the main obstacle to current flow, especially in long wires, is the residual porosity inside these powder-in-tube processed conductors that develops from bubble agglomeration when the Bi-2212 melts. In this work we tried to overcome this issue affecting the wire densification by changing the deformation process. Here we show the effects of groove rolling versus the drawing process on the critical current density J C and on the microstructure. In particular, groove-rolled multifilamentary wires show a J C increased by a factor of about 3 with respect to drawn wires prepared with the same Bi-2212 powder and architecture. We think that this approach in the deformation process is able to produce the required improvements both because the superconducting properties are enhanced and because it makes the fabrication process faster and cheaper. (paper)

  8. High-temperature abnormal behavior of resistivities for Bi-In melts

    International Nuclear Information System (INIS)

    Xi Yun; Zu Fangqiu; Li Xianfen; Yu Jin; Liu Lanjun; Li Qiang; Chen Zhihao

    2004-01-01

    The patterns of electrical resistivities versus temperature in large temperature range have been studied, using the D.C. four-probe method, for liquid Bi-In alloys (Bi-In(33 wt%), Bi-In(38 wt%), Bi-In(50.5 wt%), Bi-In(66 wt%)). The clear turning point of each resistivity-temperature curves of the liquid Bi-In alloys is observed at the temperature much above the melting point, in which temperature range the resistivity-temperature coefficient increases rapidly. Except for the turning temperature range, the resistivities of Bi-In alloys increase linearly with temperature. Because resistivity is sensitive to the structure, this experiment shows the structural transition in Bi-In melts at the temperature much higher than the liquidus. And it is suggested that there are different Bi-In short-range orderings in different Bi-In melts, so the resistivity-temperature curves have the turns at different temperatures and the resistivity-temperature coefficients are also different

  9. Large and high-quality single-crystal growth of cuprate superconductor Bi-2223 using the traveling-solvent floating-zone (TSFZ) method

    Science.gov (United States)

    Adachi, Shintaro; Usui, Tomohiro; Kosugi, Kenta; Sasaki, Nae; Sato, Kentaro; Fujita, Masaki; Yamada, Kazuyoshi; Fujii, Takenori; Watanabe, Takao

    In high superconducting transition temperature (high-Tc) cuprates, it is empirically known that Tc increases on increasing the number of CuO2 planes in a unit cell n from 1 to 3. Bi-family cuprates are ideal for investigating the microscopic mechanism involved. However, it is difficult to grow tri-layered Bi-2223, probably owing to its narrow crystallization field. Here, we report improved crystal growth of this compound using the TSFZ method under conditions slightly different from those in an earlier report [J. Cryst. Growth 223, 175 (2001)]. A Bi-rich feed-rod composition of Bi2.2Sr1.9Ca2Cu3Oy and a slightly oxygen-reduced atmosphere (mixed gas flow of O2 (10%) and Ar (90%)) were adopted for the crystal growth. In addition, to increase the supersaturation of the melts, we applied a large temperature gradient along the solid-liquid interface by shielding a high-angle light beam using Al foil around the quartz tube. In this way, we succeeded in preparing large (2 × 2 × 0 . 05 mm3) and high-quality (almost 100% pure) Bi-2223 single crystals. Hirosaki University Grant for Exploratory Research by Young Scientists and Newly-appointed Scientists.

  10. Large displacement bi-directional out-of-plane Lorentz actuator array for surface manipulation

    International Nuclear Information System (INIS)

    Park, Byoungyoul; Afsharipour, Elnaz; Chrusch, Dwayne; Shafai, Cyrus; Andersen, David; Burley, Greg

    2017-01-01

    This paper presents a large displacement out-of-plane Lorentz actuator array for surface manipulation. Actuators are formed from single crystal silicon flexible serpentine springs on either side of a rigid crossbar containing a narrow contact pillar. A rigid mounting rail system was employed to enable a 5  ×  5 array, which offers scalability of the array size. Analytical and finite element models were used to optimize actuator design. Individual actuators were tested to show linear deflection response of  ±150 µ m motion, using a  ±14.7 mA current in the presence of a 0.48 T magnetic field. This actuator array is suitable for various 2D surface modification applications due to its large deformation with low current and temperature of operation, and narrow contact area to a target surface. (paper)

  11. Non-linear seismic response of base-isolated liquid storage tanks to bi-directional excitation

    International Nuclear Information System (INIS)

    Shrimali, M.K.; Jangid, R.S.

    2002-01-01

    Seismic response of the liquid storage tanks isolated by lead-rubber bearings is investigated for bi-directional earthquake excitation (i.e. two horizontal components). The biaxial force-deformation behaviour of the bearings is considered as bi-linear modelled by coupled non-linear differential equations. The continuous liquid mass of the tank is modelled as lumped masses known as convective mass, impulsive mass and rigid mass. The corresponding stiffness associated with these lumped masses has been worked out depending upon the properties of the tank wall and liquid mass. Since the force-deformation behaviour of the bearings is non-linear, as a result, the seismic response is obtained by the Newmark's step-by-step method. The seismic responses of two types of the isolated tanks (i.e. slender and broad) are investigated under several recorded earthquake ground to study the effects of bi-directional interaction. Further, a parametric study is also carried out to study the effects of important system parameters on the effectiveness of seismic isolation for liquid storage tanks. The various important parameters considered are: (i) the period of isolation, (ii) the damping of isolation bearings and (iii) the yield strength level of the bearings. It has been observed that the seismic response of isolated tank is found to be insensitive to interaction effect of the bearing forces. Further, there exists an optimum value of isolation damping for which the base shear in the tank attains the minimum value. Therefore, increasing the bearing damping beyond a certain value may decrease the bearing and sloshing displacements but it may increase the base shear

  12. A new method for the measurement of two-phase mass flow rate using average bi-directional flow tube

    International Nuclear Information System (INIS)

    Yoon, B. J.; Uh, D. J.; Kang, K. H.; Song, C. H.; Paek, W. P.

    2004-01-01

    Average bi-directional flow tube was suggested to apply in the air/steam-water flow condition. Its working principle is similar with Pitot tube, however, it makes it possible to eliminate the cooling system which is normally needed to prevent from flashing in the pressure impulse line of pitot tube when it is used in the depressurization condition. The suggested flow tube was tested in the air-water vertical test section which has 80mm inner diameter and 10m length. The flow tube was installed at 120 of L/D from inlet of test section. In the test, the pressure drop across the average bi-directional flow tube, system pressure and average void fraction were measured on the measuring plane. In the test, fluid temperature and injected mass flow rates of air and water phases were also measured by a RTD and two coriolis flow meters, respectively. To calculate the phasic mass flow rates : from the measured differential pressure and void fraction, Chexal drift-flux correlation was used. In the test a new correlation of momentum exchange factor was suggested. The test result shows that the suggested instrumentation using the measured void fraction and Chexal drift-flux correlation can predict the mass flow rates within 10% error of measured data

  13. DFT study on the interfacial properties of vertical and in-plane BiOI/BiOIO3 hetero-structures.

    Science.gov (United States)

    Dai, Wen-Wu; Zhao, Zong-Yan

    2017-04-12

    Composite photocatalysts with hetero-structures usually favor the effective separation of photo-generated carriers. In this study, BiOIO 3 was chosen to form a hetero-structure with BiOI, due to its internal polar field and good lattice matching with BiOI. The interfacial properties and band offsets were focused on and analyzed in detail by DFT calculations. The results show that the charge depletion and accumulation mainly occur in the region near the interface. This effect leads to an interfacial electric field and thus, the photo-generated electron-hole pairs can be easily separated and transferred along opposite directions at the interface, which is significant for the enhancement of the photocatalytic activity. Moreover, according to the analysis of band offsets, the vertical BiOI/BiOIO 3 belongs to the type-II hetero-structure, while the in-plane BiOI/BiOIO 3 belongs to the type-I hetero-structure. The former type of hetero-structure has more favorable effects to enhance the photocatalytic activity of BiOI than that of the latter type of hetero-structure. In the case of the vertical BiOI/BiOIO 3 hetero-structure, photo-generated electrons can move from the conduction band of BiOI to that of BiOIO 3 , while holes can move from the valence band of BiOIO 3 to that of BiOI under solar radiation. In addition, the introduced internal electric field functions as a selector that can promote the separation of photo-generated carriers, resulting in the higher photocatalytic quantum efficiency. These findings illustrate the underlying mechanism for the reported experiments, and can be used as a basis for the design of novel highly efficient composite photocatalysts with hetero-structures.

  14. Facile Fabrication of BiOI/BiOCl Immobilized Films With Improved Visible Light Photocatalytic Performance

    Directory of Open Access Journals (Sweden)

    Yingxian Zhong

    2018-03-01

    Full Text Available HIGHLIGHTSA facial method was used to fabricate BiOI/BiOCl film at room temperature.30% BiOI/BiOCl showed an excellent photocatalytic activity and stability.Improvement of photocatalytic activity was owed to expanded visible light absorption and high separation efficiency of charge.Photocatalysis has been considered to be one of the most promising ways to photodegrade organic pollutants. Herein, a series of BiOI/BiOCl films coating on FTO were fabricated through a simple method at room temperature. The photocatalytic efficiency of 30%BiOI/BiOCl could reach more than 99% aiming to degrading RhB and MB after 90 and 120 min, respectively. Compared with BiOCl, 30%BiOI/BiOCl showed 12 times higher efficiency when degrading RhB. In comparison with BiOI, 30%BiOI/BiOCl showed 5 and 6 times higher efficiency when degrading RhB and MB, respectively. These obvious enhancements were attributed to expanded visible light absorption and high separation performance of photoinduced charge. Moreover, the photocatalytic activity of 30%BiOI/BiOCl had no obvious decrease after five recycles, suggesting that it was a promising photocatalyst for the removal of MB and RhB pollutants. Finally, the possible growth process for the BiOI/BiOCl thin films and photocatalysis mechanism were investigated in details. This work would provide insight to the reasonable construction of BiOX heterojunction and the photocatalytic mechanism in degrading organic pollutants.

  15. [Differences of bi-directional regulative effects between acu-moxibustion and Chinese materia medica interventions].

    Science.gov (United States)

    Cao, Xin; Yu, Zhi; Xu, Bin

    2012-10-01

    Bi-directional regulation is referred to a balancing effect of both acu-moxibustion and Chinese materia medica interventions when the human body is experiencing a hyperactivity or hypoactivity due to abnormal intrinsic or external factors. In the present paper, the authors analyze their identical and different characteristics from: 1) definition; 2) characters of regulative effects of acu-moxibustion therapy: A) differentiation of meridian and zangfu-organs being the basis of treatment, B) four factors (acupoint-location, body's functional state, acupoint-formula and needle-manipulation techniques) dependant, C) entirety regulation, and D) centrotaxis modulation; 3) characters of Chinese materia medica intervention: including a) correspondence between the drug property and the syndrome being the basis of the regulative effect, b) multi-factors [components (antagonist and agonist), combination, dosages and processing quality of Chinese materia medica, and functional state of the human body] dependant, c) entirety regulation, and d) both centrotaxis and deviation adjustment. In one word, the bi-directional regulation effect is one of the basic characteristics of both acu-moxibustion and Chinese materia medica in clinical practice, but their basis and modes for inducing effects are different.

  16. Steady-state analysis of the integrated natural gas and electric power system with bi-directional energy conversion

    DEFF Research Database (Denmark)

    Zeng, Qing; Fang, Jiakun; Li, Jinghua

    2016-01-01

    Nowadays, the electric power system and natural gas network are becoming increasingly coupled and interdependent. A harmonized integration of natural gas and electricity network with bi-directional energy conversion is expected to accommodate high penetration levels of renewables in terms of system...... flexibility. This work focuses on the steady-state analysis of the integrated natural gas and electric power system with bi-directional energy conversion. A unified energy flow formulation is developed to describe the nodal balance and branch flow in both systems and it is solved with the Newton......–Raphson method. Both the unification of units and the per-unit system are proposed to simplify the system description and to enhance the computation efficiency. The applicability of the proposed method is demonstrated by analyzing an IEEE-9 test system integrated with a 7-node natural gas network. Later, time...

  17. Few-Layer Nanoplates of Bi 2 Se 3 and Bi 2 Te 3 with Highly Tunable Chemical Potential

    KAUST Repository

    Kong, Desheng

    2010-06-09

    A topological insulator (TI) represents an unconventional quantum phase of matter with insulating bulk band gap and metallic surface states. Recent theoretical calculations and photoemission spectroscopy measurements show that group V-VI materials Bi2Se3, Bi2Te3, and Sb2Te3 are TIs with a single Dirac cone on the surface. These materials have anisotropic, layered structures, in which five atomic layers are covalently bonded to form a quintuple layer, and quintuple layers interact weakly through van der Waals interaction to form the crystal. A few quintuple layers of these materials are predicted to exhibit interesting surface properties. Different from our previous nanoribbon study, here we report the synthesis and characterizations of ultrathin Bi2Te3 and Bi2Se3 nanoplates with thickness down to 3 nm (3 quintuple layers), via catalyst-free vapor-solid (VS) growth mechanism. Optical images reveal thickness-dependent color and contrast for nanoplates grown on oxidized silicon (300 nm SiO2/Si). As a new member of TI nanomaterials, ultrathin TI nanoplates have an extremely large surface-to-volume ratio and can be electrically gated more effectively than the bulk form, potentially enhancing surface state effects in transport measurements. Low-temperature transport measurements of a single nanoplate device, with a high-k dielectric top gate, show decrease in carrier concentration by several times and large tuning of chemical potential. © 2010 American Chemical Society.

  18. Facile synthesis of Bi/BiOCl composite with selective photocatalytic properties

    International Nuclear Information System (INIS)

    Chen, Dongling; Zhang, Min; Lu, Qiuju; Chen, Junfang; Liu, Bitao; Wang, Zhaofeng

    2015-01-01

    This paper presents a novel and facile method to fabricate Bi/BiOCl composites with dominant (001) facets in situ via a microwave reduction route. Different characterization techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission scanning electron microscopy (TEM), UV–vis diffuse reflectance spectrometry (DRS), X-ray photoelectron spectroscopy (XPS), electron spin resonance spectroscopy (ESR), cathodoluminescence spectrum (CL), and lifetime, have been employed to investigate the structure, optical and electrical properties of the Bi/BiOCl composites. The experimental results show that the introduction of Bi particles can efficiently enhance the photocatalytic performance of BiOCl for the degradation of several dyes under ultraviolet (UV) light irradiation, especially for negative charged methyl orange (MO). Unlike the UV photocatalytic performance, such Bi/BiOCl composite shows higher degradation efficiency towards rhodamine B (RhB) than MO and methylene blue (MB) under visible light irradiation. This special photocatalytic performance can be ascribed to the synergistic effect between oxygen vacancies and Bi particles. This work provides new insights about the photodegradation mechanisms of MO, MB and RhB under UV and visible light irradiation, which would be helpful to guide the selection of an appropriate catalyst for other pollutants. - Highlights: • Bi/BiOCl composites were synthesized via a microwave reduction. • Tunable selectivity photocatalytic activity can be achieved. • Photodegradation mechanism under UV and visible light were proposed

  19. Early Childhood Media Exposure and Self-Regulation: Bi-Directional Longitudinal Associations.

    Science.gov (United States)

    Cliff, Dylan P; Howard, Steven J; Radesky, Jenny S; McNeill, Jade; Vella, Stewart A

    2018-04-26

    To investigate: i) prospective associations between media exposure (television viewing, computers, and electronic games) at 2 years and self-regulation at 4 and 6 years, and ii) bi-directional associations between media exposure and self-regulation at 4 and 6 years. We hypothesized that media exposure and self-regulation would display a negative prospective association and subsequent bi-directional inverse associations. Data from the nationally-representative Longitudinal Study of Australian Children (LSAC) when children were aged 2 (n=2786) and 4/6 years (n=3527) were used. Primary caregivers reported children's weekly electronic media exposure. A composite measure of self-regulation was computed from caregivers-, teacher-, and observer-report data. Associations were examined using linear regression and cross-lagged panel models, accounting for covariates. Lower television viewing and total media exposure at 2 years were associated with higher self-regulation at 4 years (both β -0.02; 95% confidence interval [CI] -0.03, -0.01). Lower self-regulation at 4 years was also significantly associated with higher television viewing (β -0.15; 95% CI -0.21, -0.08), electronic game use (β -0.05; 95% CI -0.09, -0.01), and total media exposure (β -0.19; 95% CI -0.29, -0.09) at 6 years. However, media exposure at 4 years was not associated with self-regulation at 6 years. Although media exposure duration at 2 years was associated with later self-regulation, and self-regulation at 4 years was associated with later media exposure, associations were of small magnitude. More research is needed examining content quality, social context, and mobile media use and child self-regulation. Copyright © 2018. Published by Elsevier Inc.

  20. L-shell ionization studies of Pb and Bi with α particles

    International Nuclear Information System (INIS)

    Dhal, B.B.; Nandi, T.; Padhi, H.C.

    1994-01-01

    Ionization cross sections for the L subshells of Pb and Bi by α-particle bombardment (2.2--8.2 MeV) have been determined from the experimental data and the currently available radiative transition probabilities, fluorescence yields, and Coster-Kronig factors. The measured ionization cross sections and their ratios are compared with the results of ECPSSR calculations [ECPSSR denotes perturbed-stationary-state (PSS) theory with energy-loss (E), Coulomb deflection (C), and relativistic (R) corrections]. The measured individual cross sections for L 1 and L 2 subshells deviated in opposite directions from the theory, whereas their sum shows good agreement. The L 3 and total ionization cross sections obtained from the data also show good agreement with the ECPSSR theory. The ionization cross-section ratios σ L1 /σ L2 and σ L3 /σ L2 show large deviations from the ECPSSR theory. The experimental x-ray production cross-section ratios are found to be in better agreement with the theoretical results obtained from using ECPSSR ionization cross sections and the decay yield data of Xu and Xu [J. Phys. B 25, 695 (1992)] rather than those obtained from using the decay yield data of Krause [J. Phys. Chem. Ref. Data 8, 307 (1979)]. The x-ray production cross sections, however, are in better agreement with the theoretical results obtained from using the decay yield data of Krause. The measured centroid energy of the Lγ lines of Pb shows large deviations at high projectile energy, whereas for Bi large deviations are found at the low-energy region

  1. Ga-Bi-Te system

    International Nuclear Information System (INIS)

    Rustamov, P.G.; Seidova, N.A.; Shakhbazov, M.G.; AN Azerbajdzhanskoj SSR, Baku. Inst. Neorganicheskoj i Fizicheskoj Khimii)

    1976-01-01

    To elucidate the nature of interaction in the system Ga-Bi-Te, a study has been made of sections GaTe-Bi 2 Te 3 , Ga 2 Te 3 -Bi, GaTe-Bi and Bi 2 Te 3 -Ga. The alloys have been prepared by direct melting of the components or their alloys with subsequent homogenizin.o annealing at 400 deg C. The study has been made by the methods of differential thermal, microstructural analysis and by microhardness measurements. On the basis of literature data and data obtained a projection of the liquidus surface of the phase diagram for the system Ga-Bi-Te has been constructed. In the ternary system there are 17 curves of monovariant equilibrium dividing the liquidus into 10 fields of primary crystallization of phases, 9 points of non-variant equilibrium of which 4 points are triple eutectics and 5 points are triple peritectics

  2. Spatially Resolved Large Magnetization in Ultrathin BiFeO3

    KAUST Repository

    Guo, Er-Jia

    2017-06-19

    Here, a quantitative magnetic depth profile across the planar interfaces in BiFeO3 /La0.7 Sr0.3 MnO3 (BFO/LSMO) superlattices using polarized neutron reflectometry is obtained. An enhanced magnetization of 1.83 ± 0.16 μB /Fe in BFO layers is observed when they are interleaved between two manganite layers. The enhanced magnetic order in BFO persists up to 200 K. The depth dependence of magnetic moments in BFO/LSMO superlattices as a function of the BFO layer thickness is also explored. The results show the enhanced net magnetic moment in BFO from the LSMO/BFO interface extends 3-4 unit cells into BFO. The interior part of a thicker BFO layer has a much smaller magnetization, suggesting it still keeps the small canted AFM state. The results exclude charge transfer, intermixing, epitaxial strain, and octahedral rotations/tilts as dominating mechanisms for the large net magnetization in BFO. An explanation-one suggested by others previously and consistent with the observations-attributes the temperature dependence of the net magnetization of BFO to strong orbital hybridization between Fe and Mn across the interfaces. Such orbital reconstruction would establish an upper temperature limit for magnetic ordering of BFO.

  3. Cooperation of electrically stimulated muscle and pneumatic muscle to realize RUPERT bi-directional motion for grasping.

    Science.gov (United States)

    Xikai Tu; Jiping He; Yue Wen; Jian Huang; Xinhan Huang; Hailong Huang; Meng Guo; Yong Yuan

    2014-01-01

    Robot-assisted rehabilitation is an active area of research to meet the demand of repetitive therapy in stroke rehabilitation. Robotic upper-extremity repetitive trainer (RUPERT) with its unidirectional pneumatic muscle actuation (PMA) can be used by most stroke patients that have difficulty moving in one direction because of a weak agonist or hyperactive antagonist. In this research, to broaden the usage of RUPERT, we not only add grasping functionality to the rehabilitation robot with the help of surface Functional Electrical Stimulation (FES) but also realize the robot joint bi-directional motion by using a PMA in cooperation with surface FES evoked paralyzed muscle force. This integrative rehabilitation strategy is explored for training patients to practice coordinated reaching and grasping functions. The effectiveness of this FES electrically evoked bio-actuator way is verified through a method that separates the mixed electromyogram (MEMG) into the electrically evoked electromyogram (EEMG) and voluntary electromyogram (VEMG). This is a promising approach to alleviate the size and mechanical complexity of the robot, thereby the cost of the joint bi-directional actuator rehabilitation robot by means of their own characteristics of stroke subjects.

  4. A new approach to magnetic circuit analysis and its application to the optimal design of a bi-directional magnetorheological brake

    International Nuclear Information System (INIS)

    Nguyen, Phuong-Bac; Choi, Seung-Bok

    2011-01-01

    This paper proposes a new approach to modeling the magnetic circuit of an MR brake and applies it to explore an engineering optimization problem. The MR brake used in this work is a bi-directional type whose range of braking torque varies from negative to positive values. The model of the bi-directional MR brake can be split into two components: the mechanical part and the magnetic circuit. While the mechanical part is modeled using Bingham's equation, an approach to modeling the magnetic circuit is proposed in this work. For verification of the effectiveness of this method, an optimal design aiming to minimize the mass subjected to the geometric and desired torque constraints is undertaken. In order to solve such an optimization problem, which consists of numerous constraints and potential local optima, a particle swarm optimization (PSO) algorithm in combination with a gradient-based repair method is proposed. The optimal solution of the problem obtained from the proposed method is then investigated and compared with that obtained from finite element analysis (FEA). In addition, an experiment on a manufactured bi-directional MR brake with the optimal parameters is undertaken to validate the accuracy of the proposed analysis methodology

  5. Facile Fabrication of BiOI/BiOCl Immobilized Films with Improved Visible Light Photocatalytic Performance

    Science.gov (United States)

    Zhong, Yingxian; Liu, Yuehua; Wu, Shuang; Zhu, Yi; Chen, Hongbin; Yu, Xiang; Zhang, Yuanming

    2018-03-01

    Photocatalysis has been considered to be one of the most promising ways to photodegrade organic pollutants. Herein, a series of BiOI/BiOCl films coating on FTO were fabricated through a simple method at room temperature. The photocatalytic efficiency of 30%BiOI/BiOCl could reach more than 99% aiming to degrading RhB and MB after 90 and 120 min, respectively. Compared with BiOCl, 30%BiOI/BiOCl showed 12 times higher efficiency when degrading RhB. In comparison with BiOI, 30%BiOI/BiOCl showed 5 and 6 times higher efficiency when degrading RhB and MB, respectively. These obvious enhancements were attributed to expanded visible light absorption and high separation performance of photoinduced charge. Moreover, the photocatalytic activity of 30%BiOI/BiOCl had no obvious decrease after 5 recycles, suggesting that it was a promising photocatalyst for the removal of MB and RhB pollutants. Finally, the possible growth process for the BiOI/BiOCl thin films and photocatalysis mechanism were investigated in details. This work would provide insight to the reasonable construction of BiOX heterojunction and the photocatalytic mechanism in degrading organic pollutants.

  6. UHD Video Transmission over Bi-Directional Underwater Wireless Optical Communication

    KAUST Repository

    Al-Halafi, Abdullah

    2018-04-02

    In this paper, we experimentally demonstrate for the first time a bi-directional underwater wireless optical communication system that is capable of transmitting an ultra high definition real-time video using a downlink channel while simultaneously receiving the feedback messages on the uplink channel. The links extend up to 4.5 m using QPSK, 16-QAM and 64-QAM modulations. The system is built using software defined platforms connected to TO-9 packaged pigtailed 520 nm directly modulated green laser diode (LD) with 1.2 GHz bandwidth as the optical transmitter for video streaming on the downlink, and an avalanche photodiode (APD) module as the downlink receiver. The uplink channel is connected to another pigtailed 450 nm directly modulated blue LD with 1.2 GHz bandwidth as the optical uplink transmitter for the feedback channel, and to a second APD as the uplink receiver. We perform laboratory experiments on different water types. The measured throughput is 15 Mbps for QPSK, and 30 Mbps for both 16-QAM and 64-QAM. We evaluate the quality of the received live video streams using Peak Signal-to-Noise Ratio and achieve values up to 16 dB for 64-QAM when streaming UHD video in harbor II water and 22 dB in clear ocean.

  7. UHD Video Transmission over Bi-Directional Underwater Wireless Optical Communication

    KAUST Repository

    Al-Halafi, Abdullah; Shihada, Basem

    2018-01-01

    In this paper, we experimentally demonstrate for the first time a bi-directional underwater wireless optical communication system that is capable of transmitting an ultra high definition real-time video using a downlink channel while simultaneously receiving the feedback messages on the uplink channel. The links extend up to 4.5 m using QPSK, 16-QAM and 64-QAM modulations. The system is built using software defined platforms connected to TO-9 packaged pigtailed 520 nm directly modulated green laser diode (LD) with 1.2 GHz bandwidth as the optical transmitter for video streaming on the downlink, and an avalanche photodiode (APD) module as the downlink receiver. The uplink channel is connected to another pigtailed 450 nm directly modulated blue LD with 1.2 GHz bandwidth as the optical uplink transmitter for the feedback channel, and to a second APD as the uplink receiver. We perform laboratory experiments on different water types. The measured throughput is 15 Mbps for QPSK, and 30 Mbps for both 16-QAM and 64-QAM. We evaluate the quality of the received live video streams using Peak Signal-to-Noise Ratio and achieve values up to 16 dB for 64-QAM when streaming UHD video in harbor II water and 22 dB in clear ocean.

  8. ROLE OF LEAF SURFACE WATER IN THE BI-DIRECTIONAL AMMONIA EXCHANGE BETWEEN THE ATMOSPHERE AND TERRESTRIAL BIOSPHERE

    Science.gov (United States)

    A field experiment was conducted to study the ammonia exchange between plants and the atmosphere in a soybean field in Duplin County, North Carolina during the summer of 2002. Measurements indicate that the net canopy-scale ammonia exchange is bi-directional and has a significant...

  9. Bi-induced band gap reduction in epitaxial InSbBi alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rajpalke, M. K.; Linhart, W. M.; Birkett, M.; Alaria, J.; Veal, T. D., E-mail: T.Veal@liverpool.ac.uk [Stephenson Institute for Renewable Energy and Department of Physics, School of Physical Sciences, University of Liverpool, Liverpool L69 7ZF (United Kingdom); Yu, K. M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Bomphrey, J. J.; Jones, T. S.; Ashwin, M. J., E-mail: M.J.Ashwin@warwick.ac.uk [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Sallis, S.; Piper, L. F. J. [Materials Science and Engineering, Binghamton University, Binghamton, New York 13902 (United States)

    2014-11-24

    The properties of molecular beam epitaxy-grown InSb{sub 1−x}Bi{sub x} alloys are investigated. Rutherford backscattering spectrometry shows that the Bi content increases from 0.6% for growth at 350 °C to 2.4% at 200 °C. X-ray diffraction indicates Bi-induced lattice dilation and suggests a zinc-blende InBi lattice parameter of 6.626 Å. Scanning electron microscopy reveals surface InSbBi nanostructures on the InSbBi films for the lowest growth temperatures, Bi droplets at intermediate temperatures, and smooth surfaces for the highest temperature. The room temperature optical absorption edge was found to change from 172 meV (7.2 μm) for InSb to ∼88 meV (14.1 μm) for InSb{sub 0.976}Bi{sub 0.024}, a reduction of ∼35 meV/%Bi.

  10. Large-scale synthesis of coiled-like shaped carbon nanotubes using bi-metal catalyst

    Science.gov (United States)

    Krishna, Vemula Mohana; Somanathan, T.; Manikandan, E.; Umar, Ahmad; Maaza, M.

    2018-02-01

    Carbon nanomaterials (CNMs), especially carbon nanotubes (CNTs) with coiled structure exhibit scientifically fascinating. They may be projected as an innovative preference to future technological materials. Coiled carbon nanotubes (c-CNTs) on a large-scale were successfully synthesized with the help of bi-metal substituted α-alumina nanoparticles catalyst via chemical vapor deposition (CVD) technique. Highly spring-like carbon nanostructures were observed by field emission scanning electron microscope (FESEM) examination. Furthermore, the obtained material has high purity, which correlates the X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) analysis. Raman spectroscopy reveals that the carbon multi layers are well graphitized and crystalline, even if they have defects in its structure due to coiled morphology. High-resolution transmission electron microscope (HRTEM) describes internal structure and dia of the product. Ultimately, results support the activity of bi-metal impregnated α-alumina nanoparticles catalyst to determine the high yield, graphitization and internal structure of the material. We have also studied the purified c-CNTs magnetic properties at room temperature and will be an added advantage in several applications.

  11. The modulation and reconstruction of a BiO layer of cuprate Bi2212

    International Nuclear Information System (INIS)

    Fan Wei; Zeng, Z

    2011-01-01

    Studies based on ab initio density functional theory show that the modulated structures of BiO surfaces of cuprate Bi2212 superconductors are spontaneously formed and closely related to the reconstructions of BiO surfaces. The reconstructions of BiO layers occur both on the surface and in the bulk, accompanied with the formations of BiO-zigzag chains and Bi 2 O 2 quadrilaterals. The structural modulations of the BiO surface are along the b axis, perpendicular to the BiO-zigzag chains along the a axis. Our calculations provide a unified understanding of the formation of modulating structures in Bi2212. Another interesting result is that electronic structures of BiO surfaces are significantly influenced by the CuO 2 layer beneath because of the structural modulations and reconstructions.

  12. A high-damping magnetorheological elastomer with bi-directional magnetic-control modulus for potential application in seismology

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Miao, E-mail: yumiao@cqu.edu.cn; Qi, Song; Fu, Jie; Zhu, Mi [Key Lab for Optoelectronic Technology and Systems, Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

    2015-09-14

    A high-damping magnetorheological elastomer (MRE) with bi-directional magnetic-control modulus is developed. This MRE was synthesized by filling NdFeB particles into polyurethane (PU)/ epoxy (EP) interpenetrating network (IPN) structure. The anisotropic samples were prepared in a permanent magnetic field and magnetized in an electromagnetic field of 1 T. Dynamic mechanical responses of the MRE to applied magnetic fields are investigated through magneto-rheometer, and morphology of MREs is observed via scanning electron microscope (SEM). Test result indicates that when the test field orientation is parallel to that of the sample's magnetization, the shear modulus of sample increases. On the other hand, when the orientation is opposite to that of the sample's magnetization, shear modulus decreases. In addition, this PU/EP IPN matrix based MRE has a high-damping property, with high loss factor and can be controlled by applying magnetic field. It is expected that the high damping property and the ability of bi-directional magnetic-control modulus of this MRE offer promising advantages in seismologic application.

  13. Reusable bi-directional 3ω sensor to measure thermal conductivity of 100-μm thick biological tissues

    Science.gov (United States)

    Lubner, Sean D.; Choi, Jeunghwan; Wehmeyer, Geoff; Waag, Bastian; Mishra, Vivek; Natesan, Harishankar; Bischof, John C.; Dames, Chris

    2015-01-01

    Accurate knowledge of the thermal conductivity (k) of biological tissues is important for cryopreservation, thermal ablation, and cryosurgery. Here, we adapt the 3ω method—widely used for rigid, inorganic solids—as a reusable sensor to measure k of soft biological samples two orders of magnitude thinner than conventional tissue characterization methods. Analytical and numerical studies quantify the error of the commonly used "boundary mismatch approximation" of the bi-directional 3ω geometry, confirm that the generalized slope method is exact in the low-frequency limit, and bound its error for finite frequencies. The bi-directional 3ω measurement device is validated using control experiments to within ±2% (liquid water, standard deviation) and ±5% (ice). Measurements of mouse liver cover a temperature ranging from -69 °C to +33 °C. The liver results are independent of sample thicknesses from 3 mm down to 100 μm and agree with available literature for non-mouse liver to within the measurement scatter.

  14. The effect of bi-directional loading on fatigue assessment of pressurized piping elbows with local thinned areas

    International Nuclear Information System (INIS)

    Balan, C.; Redekop, D.

    2005-01-01

    An elastic-plastic finite element study is conducted to determine the effect of bi-directional loading on the fatigue characteristics of pressurized 90 deg. piping elbows with local thinned areas. The analysis is conducted on pressurized piping elbows considered previously in the literature, but analyzed only for in-plane loading. Considering also the out-of-plane loading the present analysis seeks to simulate simultaneous horizontal and vertical seismic actions. A validation study is first conducted in which the present results obtained for in-plane loading are compared with previous results. Comparisons are made for deformation patterns, hoop strain histories, and reaction forces. The relative in-plane to out-of-plane load intensities to be adopted for the combined loading case is determined next. Results considering bi-directional loadings are then found for the pressurized piping elbow for a total of 23 cases of local area thinning. Finally conclusions are drawn about the significance of considering the additional out-of-plane loading

  15. Demonstration of surface transport in a hybrid Bi2Se3/Bi2Te3 heterostructure

    OpenAIRE

    Zhao, Yanfei; Chang, Cui-Zu; Jiang, Ying; DaSilva, Ashley; Sun, Yi; Wang, Huichao; Xing, Ying; Wang, Yong; He, Ke; Ma, Xucun; Xue, Qi-Kun; Wang, Jian

    2013-01-01

    In spite of much work on topological insulators (TIs), systematic experiments for TI/TI heterostructures remain absent. We grow a high quality heterostructure containing single quintuple layer (QL) of Bi2Se3 on 19 QLs of Bi2Te3 and compare its transport properties with 20 QLs Bi2Se3 and 20 QLs Bi2Te3. All three films are grown on insulating sapphire (0001) substrates by molecular beam epitaxy (MBE). In situ angle-resolved photoemission spectroscopy (ARPES) provides direct evidence that the su...

  16. Fabrication of flower-like direct Z-scheme β-Bi2O3/g-C3N4 photocatalyst with enhanced visible light photoactivity for Rhodamine B degradation

    Science.gov (United States)

    Zhang, Liping; Wang, Guohong; Xiong, Zhenzhong; Tang, Hua; Jiang, Chuanjia

    2018-04-01

    A combined hydrothermal-calcination approach is developed to synthesize hierarchical β-Bi2O3/g-C3N4 direct Z-scheme photocatalyst with enhanced visible light photoactivity for Rhodamine B (RhB) degradation. First, Bi2O2CO3 microflowers were hydrothermally prepared using Bi(NO3)3·5H2O as feedstocks, and then a series of β-Bi2O3/g-C3N4 direct Z-scheme photocatalysts were synthesized via a facile calcination method using Bi2O2CO3 and g-C3N4 as precursors. The samples were systematically characterized by various characterization technologies including X-ray diffraction, scanning and transmission electron microscopes, Fourier transform infrared spectroscopy and N2 absorption-desorption equipment. It was found that the g-C3N4 content in the precursors played a key role in affecting the photocatalytic activity of the final products. The β-Bi2O3/g-C3N4 heterojunction exhibited higher photocatalytic activity than single active components (β-Bi2O3 and g-C3N4), indicating the presence of a synergistic effect between two active components in β-Bi2O3/g-C3N4 heterojunction. Among all as-prepared catalysts, the 70 wt.% g-C3N4/Bi2O2CO3 exhibits the highest activity for RhB degradation, and the apparent reaction rate constant k (42.2 × 10-3 min-1) is 3.1 and 1.7 times as high as that of pure β-Bi2O3 (13.5 × 10-3 min-1) and g-C3N4 (25.2 × 10-3 min-1), respectively. The enhanced photocatalytic performance of β-Bi2O3/g-C3N4 heterostructure photocatalysts is mainly due to the high surface area, closely contacted interfaces between the β-Bi2O3 and g-C3N4 component, and the formation of direct Z-scheme structure in the β-Bi2O3/g-C3N4 composites.

  17. Certain physicochemical characteristics of Bi1.4Y0.6O3 prepared by the method of direct high-frequency fusion in cold crucible

    International Nuclear Information System (INIS)

    Poluyan, A.F.; Lashneva, V.V.; Vecher, A.A.; Voropaev, A.G.; Savitskij, A.A.; Tatarintsev, V.M.

    1988-01-01

    Electric properties and the nature of conductivity of Bi 1.4 V 0.6 O 3 solid solution prepared by the method of direct high-frequency melting in the cold crucible are studied. A sample of Bi 1.4 Y 0.6 O 3 composition synthesized by this technique has a higher electric conductivity value as compared with analogous polycrystal sample has a cubic face-centered structure of the τ-Bi 2 O 3 type. On the basis of experimental e.m.f. values temperature dependences of pressures of oxygen dissociation for Bi 2 O 3 and Bi 1.4 Y 0.6 O 3 are calculated. Bi 1.4 Y 0.6 O 3 solid solution has lower values of Po 2 dissociation pressure as compared with bismuth oxide. This expands the limits of its application

  18. High-resolution quantization based on soliton self-frequency shift and spectral compression in a bi-directional comb-fiber architecture

    Science.gov (United States)

    Zhang, Xuyan; Zhang, Zhiyao; Wang, Shubing; Liang, Dong; Li, Heping; Liu, Yong

    2018-03-01

    We propose and demonstrate an approach that can achieve high-resolution quantization by employing soliton self-frequency shift and spectral compression. Our approach is based on a bi-directional comb-fiber architecture which is composed of a Sagnac-loop-based mirror and a comb-like combination of N sections of interleaved single-mode fibers and high nonlinear fibers. The Sagnac-loop-based mirror placed at the terminal of a bus line reflects the optical pulses back to the bus line to achieve additional N-stage spectral compression, thus single-stage soliton self-frequency shift (SSFS) and (2 N - 1)-stage spectral compression are realized in the bi-directional scheme. The fiber length in the architecture is numerically optimized, and the proposed quantization scheme is evaluated by both simulation and experiment in the case of N = 2. In the experiment, a quantization resolution of 6.2 bits is obtained, which is 1.2-bit higher than that of its uni-directional counterpart.

  19. A novel method for sampling the suspended sediment load in the tidal environment using bi-directional time-integrated mass-flux sediment (TIMS) samplers

    Science.gov (United States)

    Elliott, Emily A.; Monbureau, Elaine; Walters, Glenn W.; Elliott, Mark A.; McKee, Brent A.; Rodriguez, Antonio B.

    2017-12-01

    Identifying the source and abundance of sediment transported within tidal creeks is essential for studying the connectivity between coastal watersheds and estuaries. The fine-grained suspended sediment load (SSL) makes up a substantial portion of the total sediment load carried within an estuarine system and efficient sampling of the SSL is critical to our understanding of nutrient and contaminant transport, anthropogenic influence, and the effects of climate. Unfortunately, traditional methods of sampling the SSL, including instantaneous measurements and automatic samplers, can be labor intensive, expensive and often yield insufficient mass for comprehensive geochemical analysis. In estuaries this issue is even more pronounced due to bi-directional tidal flow. This study tests the efficacy of a time-integrated mass sediment sampler (TIMS) design, originally developed for uni-directional flow within the fluvial environment, modified in this work for implementation the tidal environment under bi-directional flow conditions. Our new TIMS design utilizes an 'L' shaped outflow tube to prevent backflow, and when deployed in mirrored pairs, each sampler collects sediment uniquely in one direction of tidal flow. Laboratory flume experiments using dye and particle image velocimetry (PIV) were used to characterize the flow within the sampler, specifically, to quantify the settling velocities and identify stagnation points. Further laboratory tests of sediment indicate that bidirectional TIMS capture up to 96% of incoming SSL across a range of flow velocities (0.3-0.6 m s-1). The modified TIMS design was tested in the field at two distinct sampling locations within the tidal zone. Single-time point suspended sediment samples were collected at high and low tide and compared to time-integrated suspended sediment samples collected by the bi-directional TIMS over the same four-day period. Particle-size composition from the bi-directional TIMS were representative of the array of

  20. Inductorless bi-directional piezoelectric transformerbased converters: Design and control considerations

    DEFF Research Database (Denmark)

    Ekhtiari, Marzieh

    electromagnetic interference, compact, light, high power density and low cost allows for promising market in the near future. The piezoelectric transformer technology has the potential to be used in various applications e.g. motor driver for magnetic resonance imaging scans, the electronic ballast for fluorescent...... of inductorless switch-mode power supplies employing piezoelectric transformers. The main focus of this research is on the functionality of the piezoelectric transformer-based power converters and applying control techniques in order to exploit advantages of the piezoelectric transformers for the power converters...... detector applicable for switch-mode power supplies, optimum phase detector, bi-directional wide bandwidth current sensor and a comprehensive analysis of piezoelectric transformer-based switch-mode power supplies for zero-voltage switching, where all finalized with improving the unidirectional topology...

  1. Strongly compressed Bi (111) bilayer films on Bi{sub 2}Se{sub 3} studied by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, K. F.; Yang, Fang; Song, Y. R. [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Canhua; Qian, Dong; Gao, C. L.; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093 (China)

    2015-09-21

    Ultra-thin Bi films show exotic electronic structure and novel quantum effects, especially the widely studied Bi (111) film. Using reflection high-energy electron diffraction and scanning tunneling microscopy, we studied the structure and morphology evolution of Bi (111) thin films grown on Bi{sub 2}Se{sub 3}. A strongly compressed, but quickly released in-plane lattice of Bi (111) is found in the first three bilayers. The first bilayer of Bi shows a fractal growth mode with flat surface, while the second and third bilayer show a periodic buckling due to the strong compression of the in-plane lattice. The lattice slowly changes to its bulk value with further deposition of Bi.

  2. Corrosion behavior of materials in a liquid Pb-Bi spallation target

    International Nuclear Information System (INIS)

    Barbier, F.; Balbaud, F.; Deloffre, P.; Terlain, A.

    2001-01-01

    Corrosion results of austenitic and martensitic steels exposed to Pb-Bi liquid alloy (material candidate for the spallation target of ADS) are presented. They show the large influence of parameters such as the oxygen content in Pb-Bi and the Pb-Bi velocity on the corrosion. At low O 2 content (7 10 -8 wt%) in Pb-Bi the steels can suffer from significant dissolution while at high O 2 (1-2 10 -6 wt%) content they can be covered by an oxide layer which protects them from the dissolution. Moreover it is shown that, in aniso-thermal systems, the deposit chemical composition formed in the cold parts can depend on the temperature. (authors)

  3. Bismuth-boron multiple bonding in BiB_2O"- and Bi_2B"-

    International Nuclear Information System (INIS)

    Jian, Tian; Cheung, Ling Fung; Chen, Teng-Teng; Wang, Lai-Sheng

    2017-01-01

    Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal-boron double bonding is known, but boron-metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB_2O"- and Bi_2B"-, containing triple and double B-Bi bonds are presented. The BiB_2O"- and Bi_2B"- clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB_2O"- ([Bi≡B-B≡O]"-) and Bi_2B"- ([Bi=B=Bi]"-), respectively. The Bi-B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi-B double and triple bonds, opening the door to design main-group metal-boron complexes with multiple bonding. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Large-scale controllable synthesis of dumbbell-like BiVO4 photocatalysts with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Lu Yang; Luo Yongsong; Kong Dezhi; Zhang Deyang; Jia Yonglei; Zhang Xinwei

    2012-01-01

    The controllable synthesis of novel dumbbell-like BiVO 4 hierarchical nanostructures has been successfully obtained via a simple hydrothermal route. The as-synthesized products were studied by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and UV–vis absorption spectroscopy. The results showed that the nucleation and growth of the nanodumbbells were governed by an oriented aggregation growth mechanism. It is noteworthy that the concentration of poly(vinyl pyrrolidone) and the volume ratio of H 2 O to CH 3 COOH were crucial to the growth of the final nanoarchitectures. Control experiments were also carried out to investigate the factors which impact on the morphology of the products. Furthermore, the as-prepared BiVO 4 hierarchical nanostructures demonstrated the superior visible-light-driven photocatalytic efficiency, which is helpful for the separation and recycle considering their promising applications in harmful pollutants disposal. - Graphical Abstract: The controllable synthesis of novel dumbbell-like BiVO 4 hierarchical nanostructures has been successfully obtained via a simple hydrothermal route; the as-prepared BiVO 4 hierarchical nanostructures demonstrated the superior visible-light-driven photocatalytic efficiency. Highlights: ►Dumbbell-like BiVO 4 structures were synthesized and characterized for the first time. ► The volume ratios of H 2 O to CH 3 COOH were crucial to the final morphologies. ► Their photocatalytic activity was up to 90% under visible-light irradiation. ► Dumbbell-like BiVO 4 structures may utilize the pollutant disposal.

  5. Response of MnBi-Bi eutectic to freezing rate changes

    Science.gov (United States)

    Nair, M.; Fu, T.-W.; Wilcox, W. R.; Doddi, K.; Ravishankar, P. S.; Larson, D.

    1982-01-01

    Reference is made to a study by Fu and Wilcox (1981), which treated theoretically the influence on freezing rate of sudden changes in translation rate in the Bridgman-Stockbarger technique. This treatment is extended here to a linear ramped translation rate and an oscillatory freezing rate. It is found that oscillations above a few hertz are highly damped in small-diameter apparatus. An experimental test is carried out of the theoretical predictions for a sudden change of translation rate. The MnBi-Bi eutectic is solidified with current-induced interface demarcation. The experimental results accord reasonably well with theory if the silica ampoule wall is assumed to either (1) contribute only a resistance to heat exchange between the sample and the furnace wall or (2) transmit heat effectively in the axial direction by radiation. In an attempt to explain the fact that a finer microstructure is obtained in space, MnBi-Bi microstructure is determined when the freezing rate is increased or decreased rapidly. Preliminary results suggest that fiber branching does not occur as readily as fiber termination.

  6. Clinico-serologic co-relation in bi-directional ABO incompatible hemopoietic stem cell transplantation

    Directory of Open Access Journals (Sweden)

    Sabita Basu

    2015-01-01

    Full Text Available Background: The ABO blood group system is of prime significance in red cell transfusion and organ transplantation. However, ABO compatibility is not critical in allogenic hemopoietic stem cell transplantation (HSCT and approximately 40-50% of hemopoietic stem cell transplants are ABO incompatible. This incompatibility may be major, minor or bi-directional. Though there are descriptions of transfusion practice and protocols in ABO incompatible HSCT, there are considerable variations and transfusion support in these patients can be very challenging. Aims: The immunohematologic observations in two cases of bi-directional ABO incompatible HSCT have been described, and clinico-serologic correlation has been attempted. Materials and Methods: In both cases, peripheral blood stem cell harvests were obtained using the Cobe spectra cell separator. Immunohematologic assessments in the donor and recipient were done as a part of pre HSCT evaluation. Both the standard tube technique and column agglutination method (Ortho Biovue Micro Bead System was used. Antibody screen was done by column agglutination method using three cell panel (Surgiscreen cells. Isoagglutinin titration was done by the master dilution method and standard validated techniques were used. Results: The pattern of laboratory findings in the two cases was different and so were the clinical outcomes. Although there was early engraftment in the first case, the second case developed pure red cell aplasia and this was well-reflected in the immunohematologic assessments. Conclusion: Immunohematologic assessment correlated well with the clinical picture and could be used to predict clinical outcome and onset of complications in ABO incompatible HSCT.

  7. Self-Poling of BiFeO3 Thick Films.

    Science.gov (United States)

    Khomyakova, Evgeniya; Sadl, Matej; Ursic, Hana; Daniels, John; Malic, Barbara; Bencan, Andreja; Damjanovic, Dragan; Rojac, Tadej

    2016-08-03

    Bismuth ferrite (BiFeO3) is difficult to pole because of the combination of its high coercive field and high electrical conductivity. This problem is particularly pronounced in thick films. The poling, however, must be performed to achieve a large macroscopic piezoelectric response. This study presents evidence of a prominent and reproducible self-poling effect in few-tens-of-micrometer-thick BiFeO3 films. Direct and converse piezoelectric measurements confirmed that the as-sintered BiFeO3 thick films yield d33 values of up to ∼20 pC/N. It was observed that a significant self-poling effect only appears in cases when the films are heated and cooled through the ferroelectric-paraelectric phase transition (Curie temperature TC ∼ 820 °C). These self-poled films exhibit a microstructure with randomly oriented columnar grains. The presence of a compressive strain gradient across the film thickness cooled from above the TC was experimentally confirmed and is suggested to be responsible for the self-poling effect. Finally, the macroscopic d33 response of the self-poled BiFeO3 film was characterized as a function of the driving-field frequency and amplitude.

  8. Exploring bi-directional and SMS messaging for communications between Public Health Agencies and their stakeholders: a qualitative study.

    Science.gov (United States)

    Revere, Debra; Calhoun, Rebecca; Baseman, Janet; Oberle, Mark

    2015-07-08

    Communication technologies that enable bi-directional/two-way communications and cell phone texting (SMS) between public health agencies and their stakeholders may improve public health surveillance, ensure targeted distribution of alerts to hard-to-reach populations, reduce mortality and morbidity in an emergency, and enable a crucial feedback loop between public health agencies and the communities they serve. Building on prior work regarding health care provider preferences for receiving one-way public health communications by email, fax or SMS, we conducted a formative, exploratory study to understand how a bi-directional system and the incorporation of SMS in that system might be used as a strategy to send and receive messages between public health agencies and community-based organizations which serve vulnerable populations, health care providers, and public health workers. Our research question: Under what conditions and/or situations might public health agencies utilize bi-directional and/or SMS messaging for disseminating time-sensitive public health information (alerts, advisories, updates, etc.) to their stakeholders? A mixed methods (qualitative and quantitative) study was conducted between April and July 2014. Data collection included a survey distributed to health care providers and semi-structured interviews with providers, community- and government-based organization leaders and directors, and public health agency internal workforce staff. Survey respondents and interviewees were asked about their exposure to public health messages, how these messages are received and how the information in these messages are handled, and in what situations (for example, a local vs. a national event, a pandemic or emergency vs. a health update) a bi-directional and/or SMS messaging system might improve communications between public health agencies and their stakeholder group. Interview and survey data were qualitatively analyzed. Thematic codes were quantitized into

  9. A plate-on-plate sandwiched Z-scheme heterojunction photocatalyst: BiOBr-Bi{sub 2}MoO{sub 6} with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shengyao [College of Science, Huazhong Agricultural University, Wuhan 430070 (China); Key Laboratory of Environment Correlative Dietology, Ministry of Education, Wuhan 430070 (China); Yang, Xianglong; Zhang, Xuehao; Ding, Xing; Yang, Zixin [College of Science, Huazhong Agricultural University, Wuhan 430070 (China); Dai, Ke [College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Chen, Hao, E-mail: hchenhao@mail.hzau.edu.cn [College of Science, Huazhong Agricultural University, Wuhan 430070 (China); Key Laboratory of Environment Correlative Dietology, Ministry of Education, Wuhan 430070 (China)

    2017-01-01

    Highlights: • A visible light heterojunction photocatalyst of BiOBr-Bi{sub 2}MoO{sub 6} was simply synthesized. • Carriers transferred efficiently in sandwiched layers causing an enhance activity. • A possible direct Z-scheme charge transfer mechanism of BiOBr-Bi2MoO6 is proposed. - Abstract: In this study, a direct Z-scheme heterojunction BiOBr-Bi{sub 2}MoO{sub 6} with greatly enhanced visible light photocatalytic performance was fabricated via a two-step coprecipitation method. It was indicated that a plate-on-plate heterojunctions be present between BiOBr and Bi{sub 2}MoO{sub 6} through different characterization techniques including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoelectrochemical measurements. The crystal structure and morphology analysis revealed that the heterointerface in BiOBr-Bi{sub 2}MoO{sub 6} occurred mainly on the (001) facets of BiOBr and (001) facets of Bi{sub 2}MoO{sub 6}. The photocatalytic activity of the BiOBr-Bi{sub 2}MoO{sub 6} was investigated by degradation of RhB and about 66.7% total organic carbon (TOC) could be removed. Ciprofloxacin (CIP) was employed to rule out the photosensitization. It was implied that the higher activity of BiOBr-Bi{sub 2}MoO{sub 6} could be attribute to the strong redox ability in the Z-scheme system, which was subsequently confirmed by photoluminescence spectroscopy (PL) and active spices trapping experiments. This study provides a promising platform for Z-scheme heterojunction constructing and also sheds light on highly efficient visible-light-driven photocatalysts designing.

  10. Analysis and Design of Bi-Directional DC-DC Converter in the Extended Run Time DC UPS System Based on Fuel Cell and Supercapacitor

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2009-01-01

    Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes. The deli......Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes...

  11. Algorithm for counting large directed loops

    Energy Technology Data Exchange (ETDEWEB)

    Bianconi, Ginestra [Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste (Italy); Gulbahce, Natali [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, NM 87545 (United States)

    2008-06-06

    We derive a Belief-Propagation algorithm for counting large loops in a directed network. We evaluate the distribution of the number of small loops in a directed random network with given degree sequence. We apply the algorithm to a few characteristic directed networks of various network sizes and loop structures and compare the algorithm with exhaustive counting results when possible. The algorithm is adequate in estimating loop counts for large directed networks and can be used to compare the loop structure of directed networks and their randomized counterparts.

  12. Thickness and growth-condition dependence of in-situ mobility and carrier density of epitaxial thin-film Bi2Se3

    International Nuclear Information System (INIS)

    Hellerstedt, Jack; Fuhrer, Michael S.; Edmonds, Mark T.; Zheng, C. X.; Chen, J. H.; Cullen, William G.

    2014-01-01

    Bismuth selenide Bi 2 Se 3 was grown by molecular beam epitaxy, while carrier density and mobility were measured directly in situ as a function of film thickness. Carrier density shows high interface n-doping (1.5 × 10 13  cm −2 ) at the onset of film conduction and bulk dopant density of ∼5 × 10 11  cm −2 per quintuple-layer unit, roughly independent of growth temperature profile. Mobility depends more strongly on the growth temperature and is related to the crystalline quality of the samples quantified by ex-situ atomic force microscopy measurements. These results indicate that Bi 2 Se 3 as prepared by widely employed parameters is n-doped before exposure to atmosphere, the doping is largely interfacial in origin, and dopants are not the limiting disorder in present Bi 2 Se 3 films.

  13. Supercapacitors studies on BiPO4 nanoparticles synthesized via a simple microwave approach

    Directory of Open Access Journals (Sweden)

    S. Vadivel

    2017-07-01

    Full Text Available BiPO4 nanomaterial was synthesized using EDTA (ethylene diamine tetra acetic acid as the surfactant via a simple microwave method. The structure and morphology of BiPO4 were systematically characterized by X-ray diffraction (XRD, Fourier-transform infrared spectroscopy (FT-IR, and scanning electron microscopy (FE-SEM studies. The obtained BiPO4 nanoparticles were, on average, 150–300 nm. The electrochemical results showed that the specific capacitance of BiPO4 obtained using the microwave route was up to 104 Fg−1 at a current density of 1 Ag−1 with a large potential window of 1.7 V. The material showed excellent cycling stability (92% capacitance retention after 500 cycles at a current density of 1 Ag−1.

  14. Bi-directional vibration control of offshore wind turbines using a 3D pendulum tuned mass damper

    Science.gov (United States)

    Sun, C.; Jahangiri, V.

    2018-05-01

    Offshore wind turbines suffer from excessive bi-directional vibrations due to wind-wave misalignment and vortex induced vibrations. However, most of existing research focus on unidirectional vibration attenuation which is inadequate for real applications. The present paper proposes a three dimensional pendulum tuned mass damper (3d-PTMD) to mitigate the tower and nacelle dynamic response in the fore-aft and side-side directions. An analytical model of the wind turbine coupled with the 3d-PTMD is established wherein the interaction between the blades, the tower and the 3d-PTMD is modeled. Aerodynamic loading is computed using the Blade Element Momentum method where the Prandtls tip loss factor and the Glauert correction are considered. JONSWAP spectrum is adopted to generate wave data. Wave loading is computed using Morisons equation in collaboration with the strip theory. Via a numerical search approach, the design formula of the 3d-PTMD is obtained and examined on a National Renewable Energy Lab (NREL) monopile 5 MW baseline wind turbine model under misaligned wind, wave and seismic loading. Dual linear tuned mass dampers (TMDs) deployed in the fore-aft and side-side directions are utilized for comparison. It is found that the 3d-PTMD with a mass ratio of 2 % can improve the mitigation of the root mean square and peak response by around 10 % when compared with the dual linear TMDs in controlling the bi-directional vibration of the offshore wind turbines under misaligned wind, wave and seismic loading.

  15. Liquid-Phase Exfoliation into Monolayered BiOBr Nanosheets for Photocatalytic Oxidation and Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hongjian [Beijing; Huang, Hongwei [Beijing; Xu, Kang [Center; Hao, Weichang [Center; Guo, Yuxi [Beijing; Wang, Shuobo [Beijing; Shen, Xiulin [Beijing; Pan, Shaofeng [Beijing; Zhang, Yihe [Beijing

    2017-09-26

    Monolayered photocatalytic materials have attracted huge research interests in terms of their large specific surface area and ample active sites. Sillén-structured layered BiOX (X = Cl, Br, I) casts great prospects owing to their strong photo-oxidation ability and high stability. Fabrication of monolayered BiOX by a facile, low-cost, and scalable approach is highly challenging and anticipated. Herein, we describe the large-scale preparation of monolayered BiOBr nanosheets with a thickness of ~0.85 nm via a readily achievable liquid-phase exfoliation strategy with assistance of formamide at ambient conditions. The as-obtained monolayered BiOBr nanosheets are allowed diverse superiorities, such as enhanced specific surface area, promoted band structure, and strengthened charge separation. Profiting from these benefits, the advanced BiOBr monolayers not only show excellent adsorption and photodegradation performance for treating contaminants, but also demonstrate a greatly promoted photocatalytic activity for CO2 reduction into CO and CH4. Additionally, monolayered BiOI nanosheets have also been obtained by the same synthetic approach. Our work offers a mild and general approach for preparation of monolayered BiOX, and may have huge potential to be extended to the synthesis of other single-layer two-dimensional materials.

  16. Electron microscopy analyses and electrical properties of the layered Bi2WO6 phase

    International Nuclear Information System (INIS)

    Taoufyq, A.; Ait Ahsaine, H.; Patout, L.; Benlhachemi, A.; Ezahri, M.

    2013-01-01

    The bismuth tungstate Bi 2 WO 6 was synthesized using a classical coprecipitation method followed by a calcination process at different temperatures. The samples were characterized by X-ray diffraction, simultaneous thermogravimetry and differential thermal analysis (TGA/DTA), scanning and transmission electron microscopy (SEM, TEM) analyses. The Rietveld analysis and electron diffraction clearly confirmed the Pca2 1 non centrosymmetric space group previously proposed for this phase. The layers Bi 2 O 2 2+ and WO 4 2− have been directly evidenced from the HRTEM images. The electrical properties of Bi 2 WO 6 compacted pellets systems were determined from electrical impedance spectrometry (EIS) and direct current (DC) analyses, under air and argon, between 350 and 700 °C. The direct current analyses showed that the conduction observed from EIS analyses was mainly ionic in this temperature range, with a small electronic contribution. Electrical change above the transition temperature of 660 °C is observed under air and argon atmospheres. The strong conductivity increase observed under argon is interpreted in terms of formation of additional oxygen vacancies coupled with electron conduction. - Graphical abstract: High resolution transmission electron microscopy: inverse fast Fourier transform giving the layered structure of the Bi 2 WO 6 phase, with a representation of the cell dimensions (b and c vectors). The Bi 2 O 2 2+ and WO 4 2− sandwiches are visible in the IFFT image. - Highlights: • Using transmission electron microscopy, we visualize the layered structure of Bi 2 WO 6 . • Electrical analyses under argon gas show some increase in conductivity. • The phase transition at 660 °C is evidenced from electrical modification

  17. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J., E-mail: jun.cui@pnnl.gov; Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354 (United States); Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D. [Materials Sciences and Engineering Division, Ames Laboratory, Ames, Iowa 50011 (United States); Marinescu, M. [Electron Energy Corporation, Landisville, Pennsylvania 17538 (United States); Huang, Q. Z.; Wu, H. [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102 (United States); Vuong, N. V.; Liu, J. P. [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μ{sub B} at 50 K and 300 K, respectively.

  18. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    Energy Technology Data Exchange (ETDEWEB)

    Cui, J; Choi, JP; Li, G; Polikarpov, E; Darsell, J; Kramer, MJ; Zarkevich, NA; Wang, LL; Johnson, DD; Marinescu, M; Huang, QZ; Wu, H; Vuong, NV; Liu, JP

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 mu(B) at 50 K and 300 K, respectively. (C) 2014 AIP Publishing LLC.

  19. Fabrication of heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalyst and efficient photodegradation of organic contaminants under visible-light

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Meng; Li, Shuangli; Yan, Tao; Ji, Pengge; Zhao, Xia; Yuan, Kun; Wei, Dong [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Du, Bin, E-mail: dubin61@gmail.com [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

    2017-07-05

    Highlights: • The product shows efficient activity in photodegradation of RhB, BPA, and phenol. • The BBOC-10 heterojunction exhibits the best activity under visible light. • Suppressed recombination of photo-generated carriers lead to the activity enhancement. - Abstract: Heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalysts were fabricated by a facile one-pot hydrothermal method, in which melem served as the sacrificial reagent to supply carbonate anions. The as-synthesized Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction catalysts were characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscope. The XRD patterns of Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} catalysts showed the distinctive peaks of Bi{sub 2}O{sub 2}CO{sub 3} and Bi{sub 2}O{sub 4}. The SEM and TEM results showed that the pure Bi{sub 2}O{sub 2}CO{sub 3} possessed large plate morphology, while Bi{sub 2}O{sub 4} were composed of various nanorods and particles. As for Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction, it was obviously observed that Bi{sub 2}O{sub 4} nanorods and particles were grown on the surfaces of Bi{sub 2}O{sub 2}CO{sub 3} plates. The visible light driven photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction photocatalyst was evaluated by decomposing dyes, phenol, and bisphenol A in water. Compared with Bi{sub 2}O{sub 2}CO{sub 3} and Bi{sub 2}O{sub 4}, the Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalysts have exhibited remarkable enhanced activity under visible light. The excellent activity can be mainly attributed to the enhanced separation efficiency of photo-generated carriers. Controlled experiments using different radical scavengers proved that ·O{sub 2}{sup −} and h{sup +} played the main role in decomposing organic pollutants. The results of this work would

  20. Photocatalytic activity of Bi_2WO_6/Bi_2S_3 heterojunctions: the facilitation of exposed facets of Bi_2WO_6 substrate

    International Nuclear Information System (INIS)

    Yan, Long; Wang, Yufei; Shen, Huidong; Zhang, Yu; Li, Jian; Wang, Danjun

    2017-01-01

    Highlights: • Bi_2S_3/Bi_2WO_6 hybrids with exposed (020) Bi_2WO_6 facets have been synthesized. • X-ray photoelectron spectroscopy reveals that a small amount of Bi_2S_3 was formed. • The enhanced photoactivity of hybrids is due to heterojunction and (020) facets. • A possible photocatalytic degradation mechanism is proposed. - Abstract: Bi_2S_3/Bi_2WO_6 hybrid architectures with exposed (020) Bi_2WO_6 facets have been synthesized via a controlled anion exchange approach. X-ray photoelectron spectroscopy (XPS) reveals that a small amount of Bi_2S_3 was formed on the surface of Bi_2WO_6 during the anion exchange process, thus leading to the transformation from the Bi_2WO_6 to Bi_2S_3/Bi_2WO_6. A rhodamine B (RhB) aqueous solution was chosen as model organic pollutants to evaluate the photocatalytic activities of the Bi_2S_3/Bi_2WO_6 catalysts. Under visible light irradiation, the Bi_2S_3/Bi_2WO_6-TAA displayed the excellent visible light photoactivities compared with pure Bi_2S_3, Bi_2WO_6 and other composite photocatalysts. The efficient photocatalytic activity of the Bi_2S_3/Bi_2WO_6-TAA composite microspheres was ascribed to the constructed heterojunctions and the inner electric field caused by the exposed (020) Bi_2WO_6 facets. Active species trapping experiments revealed that h"+ and O_2·"− are the main active species in the photocatalytic process. Furthermore, the as-obtained photocatalysts showed good photocatalytic activity after four recycles. The results presented in this study provide a new concept for the rational design and development of highly efficient photocatalysts.

  1. Thermoelectric Properties of Cu-Doped n-Type Bi2Te2.85Se0.15 Prepared by Liquid Phase Growth Using a Sliding Boat

    Science.gov (United States)

    Kitagawa, Hiroyuki; Matsuura, Tsukasa; Kato, Toshihito; Kamata, Kin-ya

    2015-06-01

    N-type Bi2Te2.85Se0.15 thermoelectric materials were prepared by liquid phase growth (LPG) using a sliding boat, a simple and short fabrication process for Bi2Te3-related materials. Cu was selected as a donor dopant, and its effect on thermoelectric properties was investigated. Thick sheets and bars of Cu x Bi2 Te2.85Se0.15 ( x=0-0.25) of 1-2mm in thickness were obtained using the process. X-ray diffraction patterns and scanning electron micrographs showed that the in-plane direction tended to correspond to the hexagonal c-plane, which is the preferred direction for thermoelectric conversion. Cu-doping was effective in controlling conduction type and carrier (electron) concentration. The conduction type was p-type for undoped Bi2Te2.85Se0.15 and became n-type after Cu-doping. The Hall carrier concentration was increased by Cu-doping. Small resistivity was achieved in Cu0.02Bi2Te2.85Se0.15 owing to an optimized amount of Cu-doping and high crystal orientation. As a result, the maximum power factor near 310K for Cu0.02Bi2Te2.85Se0.15 was approximately 4×10-3W/K2m and had good reproducibility. Furthermore, the thermal stability of Cu0.02Bi2Te2.85Se0.15 was also confirmed by thermal cycling measurements of electrical resistivity. Thus, n-type Bi2Te2.85Se0.15 with a large power factor was prepared using the present LPG process.

  2. Bi-directional evolutionary structural optimization for strut-and-tie modelling of three-dimensional structural concrete

    Science.gov (United States)

    Shobeiri, Vahid; Ahmadi-Nedushan, Behrouz

    2017-12-01

    This article presents a method for the automatic generation of optimal strut-and-tie models in reinforced concrete structures using a bi-directional evolutionary structural optimization method. The methodology presented is developed for compliance minimization relying on the Abaqus finite element software package. The proposed approach deals with the generation of truss-like designs in a three-dimensional environment, addressing the design of corbels and joints as well as bridge piers and pile caps. Several three-dimensional examples are provided to show the capabilities of the proposed framework in finding optimal strut-and-tie models in reinforced concrete structures and verifying its efficiency to cope with torsional actions. Several issues relating to the use of the topology optimization for strut-and-tie modelling of structural concrete, such as chequerboard patterns, mesh-dependency and multiple load cases, are studied. In the last example, a design procedure for detailing and dimensioning of the strut-and-tie models is given according to the American Concrete Institute (ACI) 318-08 provisions.

  3. Transverse peltier effect in Pb-Bi{sub 2}Te{sub 3} multilayer structures

    Energy Technology Data Exchange (ETDEWEB)

    Reitmaier, Christina; Walther, Franziska; Kyarad, Amir; Lengfellner, Hans [University of Regensburg (Germany)

    2009-07-01

    Metal-semiconductor multilayer structures show, according to model calculations, large anisotropy in their electrical and thermal transport properties. Multilayer stacks consisting of alternating layers of Pb and n-type Bi{sub 2}Te{sub 3} and prepared by a heating procedure displayed large thermoelectric anisotropy up to {delta}S{approx}200 {mu} V/K, depending on the thickness ratio p=d{sub BiTe}/d{sub Pb}, where d{sub BiTe} and d{sub Pb} are the thicknesses of Bi{sub 2}Te{sub 3} and Pb layers, respectively. From multilayer stacks, tilted samples with layers inclined with respect to the sample surface where obtained by cutting stacks obliquely to the stack axis. Non-zero off-diagonal elements in the Seebeck-tensor describing the thermopower of tilted samples allow for the occurance of a transverse Peltier effect. Experimental results demonstrate cooling by the transverse Peltier effect and are compared to model calculations.

  4. 177Lu-immunotherapy of experimental peritoneal carcinomatosis shows comparable effectiveness to 213Bi-immunotherapy, but causes toxicity not observed with 213Bi

    International Nuclear Information System (INIS)

    Seidl, Christof; Zoeckler, Christine; Beck, Roswitha; Senekowitsch-Schmidtke, Reingard; Quintanilla-Martinez, Leticia; Bruchertseifer, Frank

    2011-01-01

    213 Bi-d9MAb-immunoconjugates targeting gastric cancer cells have effectively cured peritoneal carcinomatosis in a nude mouse model following intraperitoneal injection. Because the β-emitter 177 Lu has proven to be beneficial in targeted therapy, 177 Lu-d9MAb was investigated in this study in order to compare its therapeutic efficacy and toxicity with those of 213 Bi-d9MAb. Nude mice were inoculated intraperitoneally with HSC45-M2 gastric cancer cells expressing d9-E-cadherin and were treated intraperitoneally 1 or 8 days later with different activities of specific 177 Lu-d9MAb immunoconjugates targeting d9-E-cadherin or with nonspecific 177 Lu-d8MAb. Therapeutic efficacy was evaluated by monitoring survival for up to 250 days. For evaluation of toxicity, both biodistribution of 177 Lu-d9MAb and blood cell counts were determined at different time points and organs were examined histopathologically. Treatment with 177 Lu-immunoconjugates (1.85, 7.4, 14.8 MBq) significantly prolonged survival. As expected, treatment on day 1 after tumour cell inoculation was more effective than treatment on day 8, and specific 177 Lu-d9MAb conjugates were superior to nonspecific 177 Lu-d8MAb. Treatment with 7.4 MBq of 177 Lu-d9MAb was most successful, with 90% of the animals surviving longer than 250 days. However, treatment with therapeutically effective activities of 177 Lu-d9MAb was not free of toxic side effects. In some animals lymphoblastic lymphoma, proliferative glomerulonephritis and hepatocarcinoma were seen but were not observed after treatment with 213 Bi-d9MAb at comparable therapeutic efficacy. The therapeutic efficacy of 177 Lu-d9MAb conjugates in peritoneal carcinomatosis is impaired by toxic side effects. Because previous therapy with 213 Bi-d9MAb revealed comparable therapeutic efficacy without toxicity it should be preferred for the treatment of peritoneal carcinomatosis. (orig.)

  5. Myths on Bi-direction Communication of Web 2.0 Based Social Networks: Is Social Network Truly Interactive?

    Science.gov (United States)

    2011-03-10

    more and more social interactions are happening on the on-line. Especially recent uptake of the social network sites (SNSs), such as Facebook (http...Smart phones • Live updates within social networks • Facebook & Twitters Solution: WebMon for Risk Management Need for New WebMon for Social Networks ...Title: Myths on bi-direction communication of Web 2.0 based social networks : Is social network truly interactive

  6. One-step growth of nanosheet-assembled BiOCl/BiOBr microspheres for highly efficient visible photocatalytic performance

    Science.gov (United States)

    Zhang, Jinfeng; Lv, Jiali; Dai, Kai; Liang, Changhao; Liu, Qi

    2018-02-01

    In this work, we have developed a simple synthetic approach of nanosheet-assembled BiOCl/BiOBr microspheres by an ethylene glycol (EG)-assisted hydrothermal method. The crystalline form, morphology, chemical composition, optical performance and surface area of BiOCl/BiOBr microspheres were identified using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy spectra (EDX), UV-vis diffuse reflectance spectroscopy (DRS) analysis, high resolution X-ray photoelectron spectra (XPS) and N2 adsorption-desorption isotherms. BiOCl/BiOBr microspheres were nanosheet-assembled particles, which possessed visible light absorption under LED light irridation. Additionally, the methylene blue (MB) photodegradation performance of different BiOCl/BiOBr microspheres irradiated under 410 nm LED light arrays were investigated, the results exhibited that as-prepared BiOCl/BiOBr products showed higher catalytic effiency than pure BiOCl or BiOBr. By optimizing the composition ration of the BiOCl and BiOBr, up to 93% degradation rate can be obtained in the 40%BiOCl/BiOBr microspheres. Finally, the photocatalytic mechanism of BiOCl/BiOBr microspheres had been proposed.

  7. Influence of photoinduced Bi-related self-doping on the photocatalytic activity of BiOBr nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dan [School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR (China); Yue, Songtao; Wang, Wei [College of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); An, Tiacheng, E-mail: antc99@gig.ac.cn [Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Li, Guiying [Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Ye, Liqun [School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR (China); College of Chemistry and Pharmaceutical Engineering, Nanyang Normal University, Nanyang 473061 (China); Yip, Ho Yin [School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR (China); Wong, Po Keung, E-mail: pkwong@cuhk.edu.hk [School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR (China)

    2017-01-01

    Highlights: • Bi{sup 5+} self-doped BiOBr nanosheets are achieved under UV irradiation. • Bi{sup 5+} is formed due to the oxidation of surface Bi{sup 3+} by photoexcited h{sup +} of BiOBr. • Two photoinduced h{sup +} mediated oxidation processes happen simultaneously. • Self-doped BiOBr is superior in phenol degradation and bacterial inactivation. • Bi{sup 5+} electron trapping induced photocatalytic enhancement mechanism is proposed. - Abstract: Under UV irradiation, self-doped Bi{sup 5+} is evidenced to be generated on the surface of BiOBr nanosheets, but with well-preserved crystal structure and morphology compared with pure counterpart. Bi{sup 5+} self-doping BiOBr (BiOBr-4) exhibits distinct photocatalytic mode for dyes degradation, as compared with pure BiOBr nanosheets. These photodegradation distinctions are mainly due to the simultaneous occurrence of two photoinduced hole (h{sup +}) mediated oxidation processes on the BiOBr surfaces: (1) a portion of photoexcited h{sup +} participates in the photocatalytic oxidation of dyes, and (2) partial h{sup +} involves the oxidation of Bi{sup 3+} to Bi{sup 5+}. Notably, BiOBr-4 nanosheets comparatively show superior photocatalytic activity for the phenol decomposition as well as the bacterial inactivation. Besides Bi{sup 5+} induced narrowed bandgap and enhanced light adsorption capacity, significantly, the oxidative Bi{sup 5+} acts as electron traps to promote the photoexcited electron-hole separation and accelerate h{sup +} migration, resulting in the considerable photocatalytic enhancement of BiOBr-4 nanosheets. These novel findings will not only give new insights into the photocatalytic mechanism but also explore new route to enhance photocatalytic performance of Bi-based materials.

  8. Shape Optimization of the Assisted Bi-directional Glenn surgery for stage-1 single ventricle palliation

    Science.gov (United States)

    Verma, Aekaansh; Shang, Jessica; Esmaily-Moghadam, Mahdi; Wong, Kwai; Marsden, Alison

    2016-11-01

    Babies born with a single functional ventricle typically undergo three open-heart surgeries starting as neonates. The first of these stages (BT shunt or Norwood) has the highest mortality rates of the three, approaching 30%. Proceeding directly to a stage-2 Glenn surgery has historically demonstrated inadequate pulmonary flow (PF) & high mortality. Recently, the Assisted Bi-directional Glenn (ABG) was proposed as a promising means to achieve a stable physiology by assisting the PF via an 'ejector pump' from the systemic circulation. We present preliminary parametrization and optimization results for the ABG geometry, with the goal of increasing PF. To limit excessive pressure increases in the Superior Vena Cava (SVC), the SVC pressure is included as a constraint. We use 3-D finite element flow simulations coupled with a single ventricle lumped parameter network to evaluate PF & the pressure constraint. We employ a derivative free optimization method- the Surrogate Management Framework, in conjunction with the OpenDIEL framework to simulate multiple simultaneous evaluations. Results show that nozzle diameter is the most important design parameter affecting ABG performance. The application of these results to patient specific situations will be discussed. This work was supported by an NSF CAREER award (OCI1150184) and by the XSEDE National Computing Resource.

  9. Microstructure, mechanical properties, castability and in vitro biocompatibility of Ti-Bi alloys developed for dental applications.

    Science.gov (United States)

    Qiu, K J; Liu, Y; Zhou, F Y; Wang, B L; Li, L; Zheng, Y F; Liu, Y H

    2015-03-01

    In this study, the microstructure, mechanical properties, castability, electrochemical behaviors, cytotoxicity and hemocompatibility of Ti-Bi alloys with pure Ti as control were systematically investigated to assess their potential applications in the dental field. The experimental results showed that, except for the Ti-20Bi alloy, the microstructure of all other Ti-Bi alloys exhibit single α-Ti phase, while Ti-20Bi alloy is consisted of mainly α-Ti phase and a small amount of BiTi2 and BiTi3 phases. The tensile strength, hardness and wear resistance of Ti-Bi alloys were demonstrated to be improved monotonically with the increase of Bi content. The castability test showed that Ti-2Bi alloy increased the castability of pure Ti by 11.7%. The studied Ti-Bi alloys showed better corrosion resistance than pure Ti in both AS (artificial saliva) and ASFL (AS containing 0.2% NaF and 0.3% lactic acid) solutions. The concentrations of both Ti ion and Bi ion released from Ti-Bi alloys are extremely low in AS, ASF (AS containing 0.2% NaF) and ASL (AS containing 0.3% lactic acid) solutions. However, in ASFL solution, a large number of Ti and Bi ions are released. In addition, Ti-Bi alloys produced no significant deleterious effect to L929 cells and MG63 cells, similar to pure Ti, indicating a good in vitro biocompatibility. Besides, both L929 and MG63 cells perform excellent cell adhesion ability on Ti-Bi alloys. The hemolysis test exhibited that Ti-Bi alloys have an ultra-low hemolysis percentage below 1% and are considered nonhemolytic. To sum up, the Ti-2Bi alloy exhibits the optimal comprehensive performance and has great potential for dental applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. High pressure synthesis of BiS2

    DEFF Research Database (Denmark)

    Søndergaard-Pedersen, Simone; Nielsen, Morten Bormann; Bremholm, Martin

    crystal structures and electrical properties.1,2 Up until now, the most sulfur rich phase in the Bi-S phase diagram was Bi2S3.3 For BiS2 the Bi atoms have anisotropic charge distribution and more complex structures are expected when comparing the layered structures of transition metal dichalcogenides....... The possibilities of using high pressure synthesis to discover new phases in the Bi-S binary system were investigated as early as the 1960’s.4 The research led to discovery of a compound with BiS2 stoichiometry, but no structure solution of BiS2 was reported. A reason behind making this new phase is to study...... the physical properties since the related compound Bi2S3 is known to be a thermoelectric material.5 In this research the BiS2 compound was synthesized by a high pressure and high temperature method using a multi-anvil large volume press and the structure was solved by single crystal diffraction. The structure...

  11. Economic growth, energy consumption and CO2 emissions in OECD (Organization for Economic Co-operation and Development)'s transport sector: A fully modified bi-directional relationship approach

    International Nuclear Information System (INIS)

    Saboori, Behnaz; Sapri, Maimunah; Baba, Maizan bin

    2014-01-01

    This paper explores the bi-directional long-run relationship between energy consumption in the road transport sector with CO 2 emissions and economic growth in OECD countries. Using time series data from 1960 to 2008 and employing the Fully Modified Ordinary Least Squares cointegration approach, the paper shows positive significant long-run bi-directional relationship between CO 2 emissions and economic growth, road sector energy consumption and economic growth and CO 2 emissions and road sector energy consumption in all the OECD countries. To examine the response of each of the variables to shocks in the value of other variables, the generalized impulse response approach is employed. The response of CO 2 emissions to economic growth is initially positive in most cases but it is relatively shorter when compared to its initial response to the road transport sector energy consumption. Moreover, in most cases, the response of carbon emissions to the road transport sector energy consumption lasts longer than its response to economic growth. This implies that most of the CO 2 emissions from transport come from energy consumption, thus long-run policies related to the efficient use of energy and shifting to biofuel, renewable and nuclear energy can bring major benefits in mitigating GHG (Greenhouse Gas) emissions. - Highlights: • The relationship between GDP, energy and CO 2 in OECD's transport is investigated. • The Fully Modified Ordinary Least Squares cointegration approach was employed. • There is positive long-run bi-directional relationship between the variables. • The response of CO 2 to GDP is shorter than its response to the energy consumption

  12. Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

    Directory of Open Access Journals (Sweden)

    Hao-Min Xu

    2016-11-01

    Full Text Available Pure BiFeO3 and heterostructured BiFeO3/BiFe0.95Mn0.05O3 (5% Mn-doped BiFeO3 thin films have been prepared by a chemical deposition method. The band structures and photosensitive properties of these films have been investigated elaborately. Pure BiFeO3 films showed stable and strong response to photo illumination (open circuit potential kept −0.18 V, short circuit photocurrent density was −0.023 mA·cm−2. By Mn doping, the energy band positions shifted, resulting in a smaller band gap of BiFe0.95Mn0.05O3 layer and an internal field being built in the BiFeO3/BiFe0.95Mn0.05O3 interface. BiFeO3/BiFe0.95Mn0.05O3 and BiFe0.95Mn0.05O3 thin films demonstrated poor photo activity compared with pure BiFeO3 films, which can be explained by the fact that Mn doping brought in a large amount of defects in the BiFe0.95Mn0.05O3 layers, causing higher carrier combination and correspondingly suppressing the photo response, and this negative influence was more considerable than the positive effects provided by the band modulation.

  13. Targeting SR-BI for cancer diagnostics, imaging and therapy

    Directory of Open Access Journals (Sweden)

    Maneesha Amrita Rajora

    2016-09-01

    Full Text Available Scavenger receptor class B type I (SR-BI plays an important role in trafficking cholesteryl esters between the core of high density lipoprotein and the liver. Interestingly, this integral membrane protein receptor is also implicated in the metabolism of cholesterol by cancer cells, whereby overexpression of SR-BI has been observed in a number of tumours and cancer cell lines, including breast and prostate cancers. Consequently, SR-BI has recently gained attention as a cancer biomarker and exciting target for the direct cytosolic delivery of therapeutic agents. This brief review highlights these key developments in SR-BI-targeted cancer therapies and imaging probes. Special attention is given to the exploration of high density lipoprotein nanomimetic platforms that take advantage of upregulated SR-BI expression to facilitate targeted drug-delivery and cancer diagnostics, and promising future directions in the development of these agents.

  14. Room-temperature in situ fabrication of Bi2O3/g-C3N4 direct Z-scheme photocatalyst with enhanced photocatalytic activity

    Science.gov (United States)

    He, Rongan; Zhou, Jiaqian; Fu, Huiqing; Zhang, Shiying; Jiang, Chuanjia

    2018-02-01

    Constructing direct Z-scheme heterojunction is an effective approach to separating photogenerated charge carriers and improving the activity of semiconductor photocatalysts. Herein, a composite of bismuth(III) oxide (Bi2O3) and graphitic carbon nitride (g-C3N4) was in situ fabricated at room temperature by photoreductive deposition of Bi3+ and subsequent air-oxidation of the resultant metallic Bi. Quantum-sized ω-Bi2O3 nanoparticles approximately 6 nm in diameter were uniformly distributed on the surface of mesoporous g-C3N4. The as-prepared Bi2O3/g-C3N4 composite exhibited higher photocatalytic activity than pure Bi2O3 and g-C3N4 for photocatalytic degradation of phenol under visible light. Reactive species trapping experiments revealed that superoxide radicals and photogenerated holes played important roles in the photocatalytic degradation of phenol. The enhanced photocatalytic activity, identification of reactive species and higher rate of charge carrier recombination (as indicated by stronger photoluminescence intensity) collectively suggest that the charge migration within the Bi2O3/g-C3N4 composite followed a Z-scheme mechanism. Photogenerated electrons on the conduction band of Bi2O3 migrate to the valence band of g-C3N4 and combine with photogenerated holes therein. At the cost of these less reactive charge carriers, the Z-scheme heterojunction enables efficient charge separation, while preserving the photogenerated electrons and holes with stronger redox abilities, which is beneficial for enhanced photocatalytic activity.

  15. Investigating Cross-Device Interaction between a Handheld Device and a Large Display

    DEFF Research Database (Denmark)

    Paay, Jeni; Raptis, Dimitrios; Kjeldskov, Jesper

    2017-01-01

    and mid-air gestures, pinching, swiping, swinging and flicking. We look specifically at their relative efficiency, effectiveness and accuracy in bi-directional interaction between a smartphone and large display in a point-click context. We report findings from two user studies, which show that swiping...... is both most effective, fastest and most accurate, closely followed by swinging. What these two approaches have in common is the ability to keep the pointer steady on the large display, unaffected by concurrent gestures or body movements used to complete the interaction, suggesting...

  16. The Origin of the Superstructure in Bi2Sr2CaCu2O8+dgr as Revealed by Scanning Tunneling Microscopy.

    Science.gov (United States)

    Kirk, M D; Nogami, J; Baski, A A; Mitzi, D B; Kapitulnik, A; Geballe, T H; Quate, C F

    1988-12-23

    Real-space images with atomic resolution of the BiO plane of Bi(2)Sr(2)CaCu(2)O(8+delta) were obtained with a scanning tunneling microscope. Single-crystal samples were cleaved and imaged under ultrahigh vacuum conditions at room temperature. The images clearly show the one-dimensional incommensurate superstructure along the b-axis that is common to this phase. High-resolution images show the position of the Bi atoms, revealing the structural nature of the superlattice. A missing row of Bi atoms occurs either every nine or ten atomic sites in both (110) directions, accounting for the measured incommensurate periodicity of the superstructure. A model is proposed that includes missing rows of atoms, as well as displacements of the atomic positions along both the a- and c-axis directions.

  17. The origin of the superstructure in Bi2Sr2CaCu2O(8+delta) as revealed by scanning tunneling microscopy

    Science.gov (United States)

    Kirk, M. D.; Nogami, J.; Baski, A. A.; Mitzi, D. B.; Kapitulnik, A.

    1988-12-01

    Real-space images with atomic resolution of the BiO plane of Bi2Sr2CaCu2O(8+delta) were obtained with a scanning tunneling microscope. Single-crystal samples were cleaved and imaged under ultrahigh vacuum conditions at room temperature. The images clearly show the one-dimensional incommensurate superstructure along the b-axis that is common to this phase. High-resolution images show the position of the Bi atoms, revelaing the structural nature of the superlattice. A missing row of Bi atoms occurs either every nine or ten atomic sites in both 110-line directions, accounting for the measured incommensurate periodicity of the superstructure. A model is proposed that includes missing rows of atoms, as well as displacements of the atomic positions along both the a- and c-axis directions.

  18. An analysis of periodic solutions of bi-directional associative memory networks with time-varying delays

    International Nuclear Information System (INIS)

    Cao Jinde; Jiang Qiuhao

    2004-01-01

    In this Letter, several sufficient conditions are derived for the existence and uniqueness of periodic oscillatory solution for bi-directional associative memory (BAM) networks with time-varying delays by employing a new Lyapunov functional and an elementary inequality, and all other solutions of the BAM networks converge exponentially to the unique periodic solution. These criteria are presented in terms of system parameters and have important leading significance in the design and applications of periodic neural circuits for delayed BAM. As an illustration, two numerical examples are worked out using the results obtained

  19. PROTOTIPE VIDEO EDITOR DENGAN MENGGUNAKAN DIRECT X DAN DIRECT SHOW

    Directory of Open Access Journals (Sweden)

    Djoni Haryadi Setiabudi

    2004-01-01

    Full Text Available Technology development had given people the chance to capture their memorable moments in video format. A high quality digital video is a result of a good editing process. Which in turn, arise the new need of an editor application. In accordance to the problem, here the process of making a simple application for video editing needs. The application development use the programming techniques often applied in multimedia applications, especially video. First part of the application will begin with the video file compression and decompression, then we'll step into the editing part of the digital video file. Furthermore, the application also equipped with the facilities needed for the editing processes. The application made with Microsoft Visual C++ with DirectX technology, particularly DirectShow. The application provides basic facilities that will help the editing process of a digital video file. The application will produce an AVI format file after the editing process is finished. Through the testing process of this application shows the ability of this application to do the 'cut' and 'insert' of video files in AVI, MPEG, MPG and DAT formats. The 'cut' and 'insert' process only can be done in static order. Further, the aplication also provide the effects facility for transition process in each clip. Lastly, the process of saving the new edited video file in AVI format from the application. Abstract in Bahasa Indonesia : Perkembangan teknologi memberi kesempatan masyarakat untuk mengabadikan saat - saat yang penting menggunakan video. Pembentukan video digital yang baik membutuhkan proses editing yang baik pula. Untuk melakukan proses editing video digital dibutuhkan program editor. Berdasarkan permasalahan diatas maka pada penelitian ini dibuat prototipe editor sederhana untuk video digital. Pembuatan aplikasi memakai teknik pemrograman di bidang multimedia, khususnya video. Perencanaan dalam pembuatan aplikasi tersebut dimulai dengan pembentukan

  20. Optical spectroscopy and Fermi surface studies of BiTeCl and BiTeBr

    Science.gov (United States)

    Martin, Catalin; Suslov, A. V.; Buvaev, S.; Hebard, A. F.; Bugnon, Philippe; Berger, Helmuth; Magrez, Arnaud; Tanner, D. B.

    2014-03-01

    The observation of a large bulk Rashba effect in the non-centrosymmetric semiconductors BiTeX(X=Cl, Br, I) has stimulated the interest in these sys- tems, as promising candidates for studying spin related phenomena and for the realization of spin devices. Here we present a comparative study of the electronic properties of BiTeCl and BiTeBr, determined from temperature dependent infrared spectroscopy and Shubnikov-de Haas oscillations. In par- ticular, we compare the angle dependence of quantum oscillations between the two compounds and discuss possible differences between the topology of their Fermi surfaces. Supported by NSF Cooperative Agreement DMR-1157490 to the National High Magnetic Field Laboratory.

  1. A New Control Method for a Bi-Directional Phase-Shift-Controlled DC-DC Converter with an Extended Load Range

    Directory of Open Access Journals (Sweden)

    Wenzheng Xu

    2017-10-01

    Full Text Available Phase-shifted converters are practically important to provide high conversion efficiencies through soft-switching techniques. However, the limitation on a resonant inductor current in the converters often leads to a non-fulfillment of the requirement of minimum load current. This paper presents a new power electronics control technique to enable the dual features of bi-directional power flow and an extended load range for soft-switching in phase-shift-controlled DC-DC converters. The proposed technique utilizes two identical full bridge converters and inverters in conjunction with a new control logic for gate-driving signals to facilitate both Zero Current Switching (ZCS and Zero Voltage Switching (ZVS in a single phase-shift-controlled DC-DC converter. The additional ZCS is designed for light load conditions at which the minimum load current cannot be attained. The bi-directional phase-shift-controlled DC-DC converter can implement the function of synchronous rectification. Its fast dynamic response allows for quick energy recovery during the regenerative braking of traction systems in electrified trains.

  2. Cs2AgBiBr6 single-crystal X-ray detectors with a low detection limit

    Science.gov (United States)

    Pan, Weicheng; Wu, Haodi; Luo, Jiajun; Deng, Zhenzhou; Ge, Cong; Chen, Chao; Jiang, Xiaowei; Yin, Wan-Jian; Niu, Guangda; Zhu, Lujun; Yin, Lixiao; Zhou, Ying; Xie, Qingguo; Ke, Xiaoxing; Sui, Manling; Tang, Jiang

    2017-11-01

    Sensitive X-ray detection is crucial for medical diagnosis, industrial inspection and scientific research. The recently described hybrid lead halide perovskites have demonstrated low-cost fabrication and outstanding performance for direct X-ray detection, but they all contain toxic Pb in a soluble form. Here, we report sensitive X-ray detectors using solution-processed double perovskite Cs2AgBiBr6 single crystals. Through thermal annealing and surface treatment, we largely eliminate Ag+/Bi3+ disordering and improve the crystal resistivity, resulting in a detector with a minimum detectable dose rate as low as 59.7 nGyair s-1, comparable to the latest record of 0.036 μGyair s-1 using CH3NH3PbBr3 single crystals. Suppressed ion migration in Cs2AgBiBr6 permits relatively large external bias, guaranteeing efficient charge collection without a substantial increase in noise current and thus enabling the low detection limit.

  3. Direct observation of anisotropic small-hole polarons in an orthorhombic structure of BiV O4 films

    Science.gov (United States)

    Chaudhuri, A.; Mandal, L.; Chi, X.; Yang, M.; Scott, M. C.; Motapothula, M.; Yu, X. J.; Yang, P.; Shao-Horn, Y.; Venkatesan, T.; Wee, A. T. S.; Rusydi, A.

    2018-05-01

    Here, we report an anisotropic small-hole polaron in an orthorhombic structure of BiV O4 films grown by pulsed-laser deposition on yttrium-doped zirconium oxide substrate. The polaronic state and electronic structure of BiV O4 films are revealed using a combination of polarization-dependent x-ray absorption spectroscopy at V L3 ,2 edges, spectroscopic ellipsometry, x-ray photoemission spectroscopies, and high-resolution x-ray diffraction with the support of first-principles calculations. We find that in the orthorhombic phase, which is slightly different from the conventional pucherite structure, the unoccupied V 3d orbitals and charge inhomogeneities lead to an anisotropic small-hole polaron state. Our result shows the importance of the interplay of charge and lattice for the formation of a hole polaronic state, which has a significant impact in the electrical conductivity of BiV O4 , hence its potential use as a photoanode for water splitting.

  4. Preparation, characterization and enhanced visible-light photocatalytic activities of BiPO4/BiVO4 composites

    International Nuclear Information System (INIS)

    Wu, Siyuan; Zheng, Hong; Lian, Youwei; Wu, Yiying

    2013-01-01

    Graphical abstract: - Highlights: • BiPO 4 /BiVO 4 composites were successfully prepared by the hydrothermal method. • BiPO 4 /BiVO 4 composites exhibited broad absorption in the visible region. • Visible-light photocatalytic activities of BiPO 4 /BiVO 4 composites were enhanced. • P/V molar ratio and pH value of the reaction affect photocatalytic activity. • The mechanism of enhanced visible-light photocatalytic activities was discussed. - Abstract: BiPO 4 /BiVO 4 composites with different P/V molar ratios were prepared by the hydrothermal method and the effect of pH values of hydrothermal reaction on photocatalytic activity of BiPO 4 /BiVO 4 composite was investigated. The photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic property of BiPO 4 /BiVO 4 was evaluated by photocatalytic degradation of Methylene blue under visible light irradiation. The results showed that the photocatalytic activity of the composites was much higher than that of pure BiPO 4 and BiVO 4 . The rate constant of Methylene blue degradation over BiPO 4 /BiVO 4 (P/V molar ratio of 5:1 and hydrothermal reaction pH value of 1.5) is 1.7 times that of pure BiVO 4 . The photocatalytic activity enhancement of BiPO 4 /BiVO 4 composite is closely related to the BiVO 4 functioning as a sensitizer to adsorb visible light and the heterojunction of BiPO 4 /BiVO 4 acting as an active center for hindering the rapid recombination of electron–hole pairs during the photocatalytic reaction

  5. Performance analysis of bi-directional broadband passive optical network using erbium-doped fiber amplifier

    Science.gov (United States)

    Almalaq, Yasser; Matin, Mohammad A.

    2014-09-01

    The broadband passive optical network (BPON) has the ability to support high-speed data, voice, and video services to home and small businesses customers. In this work, the performance of bi-directional BPON is analyzed for both down and up streams traffic cases by the help of erbium doped fiber amplifier (EDFA). The importance of BPON is reduced cost. Because PBON uses a splitter the cost of the maintenance between the providers and the customers side is suitable. In the proposed research, BPON has been tested by the use of bit error rate (BER) analyzer. BER analyzer realizes maximum Q factor, minimum bit error rate, and eye height.

  6. Thermoelectric properties of Bi2Te3 base solid solutions in the Bi2Te3-InS system

    International Nuclear Information System (INIS)

    Safarov, M.G.; Rustamov, P.G.; Alidzhanov, M.A.

    1979-01-01

    The rich Bi 2 Te 3 part ot the Bi 2 Te 3 -InS constitutional diagram has been studied with a view to produce new Bi 2 Te 3 -based solid solutions and to establish the maximum solubility of InS in Bi 2 Te 3 . The methods of differential-thermal, X-ray phase and microstructural analysis have been used. The alloys microhardness, density and thermal electric properties have been measured. A large region of Bi 2 Te 3 -based restricted solid solutions has been detected; it reaches 14.0 mol.% InS at room temperature. Studied have been the thermoelectromotive forces, electric and thermal conductivity of the alloys, containing up to 5 mol.% InS in the 300-700 K temperature range

  7. Electronic structure of superconducting Bi2212 crystal by angle resolved ultra violet photoemission

    International Nuclear Information System (INIS)

    Saini, N.L.; Shrivastava, P.; Garg, K.B.

    1993-01-01

    The electronic structure of a high quality superconducting Bi 2 Sr 2 CaCu 2 Osub(8+δ) (Bi2212) single crystal is studied by angle resolved ultra violet photoemission (ARUPS) using He I (21.2 eV). Our results appear to show two bands crossing the Fermi level in ΓX direction of the Brillouin zone as reported by Takahashi et al. The bands at higher binding energy do not show any appreciable dispersion. The nature of the states near the Fermi level is discussed and the observed band structure is compared with the band structure calculations. (author)

  8. Parenting and Anxiety: Bi-directional Relations in Young Children.

    Science.gov (United States)

    Gouze, Karen R; Hopkins, Joyce; Bryant, Fred B; Lavigne, John V

    2017-08-01

    Developmental psychopathologists have long posited a reciprocal relation between parenting behaviors and the development of child anxiety symptoms. Yet, little empirical research has utilized a longitudinal design that would allow exploration of this bi-directional influence. The present study examined the reciprocal relations between parental respect for autonomy, parental hostility, and parental support, and the development of childhood anxiety during a critical developmental period-the transition from preschool to kindergarten and then first grade. Study participants included a community sample of 391 male and 405 female socioeconomically, racially and ethnically diverse 4 to 6-7 year olds. 54 % of the sample was White, non-Hispanic, 16.8 % was African American, 20.4 % was Hispanic, 2.4 % were Asian and 4.4 % self-identified as Other or mixed race. Parent report and observational methodology were used. Parenting and anxiety were found to interact reciprocally over time. Higher levels of age 4 anxiety led to reduced respect for child autonomy at age 5. At age 4 higher levels of parental hostility led to small increases in age 5 anxiety, and increased age 5 anxiety led to increased levels of age 6 parent hostility. Parental support at age 5 resulted in decreased anxiety symptoms at age 6-7 while higher age 5 anxiety levels were associated with reductions in age 6-7 parental support. No relations were found between these variables at the younger ages. Although the magnitude of these findings was small, they suggest that early treatment for childhood anxiety should include both parent intervention and direct treatment of the child's anxiety symptoms.

  9. Novel ultrathin Bi2O3 nanowires for supercapacitor electrode materials with high performance

    Science.gov (United States)

    Qiu, Yongfu; Fan, Hongbo; Chang, Xueyi; Dang, Haifeng; Luo, Qun; Cheng, Zhiyu

    2018-03-01

    In this paper, the ultrathin Bi2O3 nanowires are synthesized by an oxidative metal vapor transport deposition technique. Their diameters and length are about 10 nm and several tens of micrometers, the growth direction is along [101] and the specific surface area is about 7.34 m2 g-1. The galvanostatic charge-discharge measurement results show that the specific capacitances of the Bi2O3 nanowires-based electrodes increase with the decrease of the current densities. The maximum capacitance is 691.3 F g-1 at the current density of 2.0 A g-1. The Ragone plot shows that the Bi2O3 nanowires has excellent supercapacitive performance. Moreover, the cyclic stability is measured by the galvanostatic charge/discharge technique at a constant current density of 10.0 A g-1 in 6.0 M KOH electrolyte. The results show the excellent capacitance retention of 75.5% over 3000 cycles. In a word, the Bi2O3 nanowires should be the ideal potential electrode materials for low-costing and effective electrochemical supercapacitors.

  10. Metaheuristics for bi-level optimization

    CERN Document Server

    2013-01-01

    This book provides a complete background on metaheuristics to solve complex bi-level optimization problems (continuous/discrete, mono-objective/multi-objective) in a diverse range of application domains. Readers learn to solve large scale bi-level optimization problems by efficiently combining metaheuristics with complementary metaheuristics and mathematical programming approaches. Numerous real-world examples of problems demonstrate how metaheuristics are applied in such fields as networks, logistics and transportation, engineering design, finance and security.

  11. Fuzzy Bi-level Decision-Making Techniques: A Survey

    Directory of Open Access Journals (Sweden)

    Guangquan Zhang

    2016-04-01

    Full Text Available Bi-level decision-making techniques aim to deal with decentralized management problems that feature interactive decision entities distributed throughout a bi-level hierarchy. A challenge in handling bi-level decision problems is that various uncertainties naturally appear in decision-making process. Significant efforts have been devoted that fuzzy set techniques can be used to effectively deal with uncertain issues in bi-level decision-making, known as fuzzy bi-level decision-making techniques, and researchers have successfully gained experience in this area. It is thus vital that an instructive review of current trends in this area should be conducted, not only of the theoretical research but also the practical developments. This paper systematically reviews up-to-date fuzzy bi-level decisionmaking techniques, including models, approaches, algorithms and systems. It also clusters related technique developments into four main categories: basic fuzzy bi-level decision-making, fuzzy bi-level decision-making with multiple optima, fuzzy random bi-level decision-making, and the applications of bi-level decision-making techniques in different domains. By providing state-of-the-art knowledge, this survey paper will directly support researchers and practitioners in their understanding of developments in theoretical research results and applications in relation to fuzzy bi-level decision-making techniques.

  12. Investigating Cross-Device Interaction between a Handheld Device and a Large Display

    DEFF Research Database (Denmark)

    Paay, Jeni; Raptis, Dimitrios; Kjeldskov, Jesper

    2017-01-01

    and mid-air gestures, pinching, swiping, swinging and flicking. We look specifically at their relative efficiency, effectiveness and accuracy in bi-directional interaction between a smartphone and large display in a point-click context. We report findings from two user studies, which show that swiping...... is both most effective, fastest and most accurate, closely followed by swinging. What these two approaches have in common is the ability to keep the pointer steady on the large display, unaffected by concurrent gestures or body movements used to complete the interaction, suggesting...... that this is an important factor for designing effective cross-device interaction with large displays....

  13. ParBiBit: Parallel tool for binary biclustering on modern distributed-memory systems.

    Science.gov (United States)

    González-Domínguez, Jorge; Expósito, Roberto R

    2018-01-01

    Biclustering techniques are gaining attention in the analysis of large-scale datasets as they identify two-dimensional submatrices where both rows and columns are correlated. In this work we present ParBiBit, a parallel tool to accelerate the search of interesting biclusters on binary datasets, which are very popular on different fields such as genetics, marketing or text mining. It is based on the state-of-the-art sequential Java tool BiBit, which has been proved accurate by several studies, especially on scenarios that result on many large biclusters. ParBiBit uses the same methodology as BiBit (grouping the binary information into patterns) and provides the same results. Nevertheless, our tool significantly improves performance thanks to an efficient implementation based on C++11 that includes support for threads and MPI processes in order to exploit the compute capabilities of modern distributed-memory systems, which provide several multicore CPU nodes interconnected through a network. Our performance evaluation with 18 representative input datasets on two different eight-node systems shows that our tool is significantly faster than the original BiBit. Source code in C++ and MPI running on Linux systems as well as a reference manual are available at https://sourceforge.net/projects/parbibit/.

  14. Topological Phase Transition-Induced Triaxial Vector Magnetoresistance in (Bi1-xInx)2Se3 Nanodevices.

    Science.gov (United States)

    Zhang, Minhao; Wang, Huaiqiang; Mu, Kejun; Wang, Pengdong; Niu, Wei; Zhang, Shuai; Xiao, Guiling; Chen, Yequan; Tong, Tong; Fu, Dongzhi; Wang, Xuefeng; Zhang, Haijun; Song, Fengqi; Miao, Feng; Sun, Zhe; Xia, Zhengcai; Wang, Xinran; Xu, Yongbing; Wang, Baigeng; Xing, Dingyu; Zhang, Rong

    2018-02-27

    We report the study of a triaxial vector magnetoresistance (MR) in nonmagnetic (Bi 1-x In x ) 2 Se 3 nanodevices at the composition of x = 0.08. We show a dumbbell-shaped in-plane negative MR up to room temperature as well as a large out-of-plane positive MR. MR at three directions is about in a -3%:-1%:225% ratio at 2 K. Through both the thickness and composition-dependent magnetotransport measurements, we show that the in-plane negative MR is due to the topological phase transition enhanced intersurface coupling near the topological critical point. Our devices suggest the great potential for room-temperature spintronic applications in, for example, vector magnetic sensors.

  15. Electron microscopy analyses and electrical properties of the layered Bi{sub 2}WO{sub 6} phase

    Energy Technology Data Exchange (ETDEWEB)

    Taoufyq, A. [Institut Matériaux Microélectronique et Nanosciences de Provence, IM2NP, UMR CNRS 7334, Université du Sud Toulon-Var, BP 20132, 83957, La Garde Cedex (France); Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc (Morocco); Département d‘Études des Réacteurs, Laboratoire Dosimétrie Capteurs Instrumentation, CEA Cadarache (France); Société CESIGMA—Signals and Systems, 1576 Chemin de La Planquette, F 83 130 LA GARDE (France); Ait Ahsaine, H. [Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc (Morocco); Patout, L. [Institut Matériaux Microélectronique et Nanosciences de Provence, IM2NP, UMR CNRS 7334, Université du Sud Toulon-Var, BP 20132, 83957, La Garde Cedex (France); Benlhachemi, A.; Ezahri, M. [Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc (Morocco); and others

    2013-07-15

    The bismuth tungstate Bi{sub 2}WO{sub 6} was synthesized using a classical coprecipitation method followed by a calcination process at different temperatures. The samples were characterized by X-ray diffraction, simultaneous thermogravimetry and differential thermal analysis (TGA/DTA), scanning and transmission electron microscopy (SEM, TEM) analyses. The Rietveld analysis and electron diffraction clearly confirmed the Pca2{sub 1} non centrosymmetric space group previously proposed for this phase. The layers Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} have been directly evidenced from the HRTEM images. The electrical properties of Bi{sub 2}WO{sub 6} compacted pellets systems were determined from electrical impedance spectrometry (EIS) and direct current (DC) analyses, under air and argon, between 350 and 700 °C. The direct current analyses showed that the conduction observed from EIS analyses was mainly ionic in this temperature range, with a small electronic contribution. Electrical change above the transition temperature of 660 °C is observed under air and argon atmospheres. The strong conductivity increase observed under argon is interpreted in terms of formation of additional oxygen vacancies coupled with electron conduction. - Graphical abstract: High resolution transmission electron microscopy: inverse fast Fourier transform giving the layered structure of the Bi{sub 2}WO{sub 6} phase, with a representation of the cell dimensions (b and c vectors). The Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} sandwiches are visible in the IFFT image. - Highlights: • Using transmission electron microscopy, we visualize the layered structure of Bi{sub 2}WO{sub 6}. • Electrical analyses under argon gas show some increase in conductivity. • The phase transition at 660 °C is evidenced from electrical modification.

  16. Photoreduction of non-noble metal Bi on the surface of Bi{sub 2}WO{sub 6} for enhanced visible light photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaojing [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China); Yu, Shan; Liu, Yang; Zhang, Qian [The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China); Zhou, Ying, E-mail: yzhou@swpu.edu.cn [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, No. 8, Xindu Road, Xindu District, Chengdu 610500 (China)

    2017-02-28

    Highlights: • Bi{sub 2}WO{sub 6}-Bi composite was synthesized by in situ photoreduction of Bi{sub 2}WO{sub 6}. • Bi{sub 2}WO{sub 6}-Bi exhibits improved photocatalytic efficiency towards degradation of Rhodamine B. • The generation of elemental Bi in Bi{sub 2}WO{sub 6}-Bi induces vacancy and structure distortion of Bi{sub 2}WO{sub 6}. • The surface oxygen adsorption mode changes from hydroxyl group on Bi{sub 2}WO{sub 6} to molecular oxygen on Bi{sub 2}WO{sub 6}-Bi. - Abstract: In this report, Bi{sub 2}WO{sub 6}-Bi composite was prepared through an in situ photoreduction method and was characterized systematically by X-Ray diffraction, transmission electron microscopy, X-Ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The as-prepared Bi{sub 2}WO{sub 6}-Bi maintains the same crystal structure with the pristine Bi{sub 2}WO{sub 6} regardless of some surface defects. Nevertheless, these surface defects result in the change of surface oxygen adsorption mode from hydroxyl to molecular oxygen on Bi{sub 2}WO{sub 6}. Photocatalytic activity over Bi{sub 2}WO{sub 6}-Bi is 2.4 times higher than that of Bi{sub 2}WO{sub 6} towards the degradation of organic dye Rhodamine B (RhB) under visible light irradiation (λ > 420 nm). A deep study shows that cleavage of benzene ring is the main pathway for RhB degradation over Bi{sub 2}WO{sub 6}, but both the benzene cleavage and de-ethylation pathway coexist for RhB decomposition in the presence of Bi{sub 2}WO{sub 6}-Bi as the photocatalyst. Photoelectrochemical study including transient photocurrent tests and electrochemical impedance spectroscopy measurements shows that Bi{sub 2}WO{sub 6}-Bi could facilitate the charge transfer process compared to Bi{sub 2}WO{sub 6}. These data above has indicated a new insight into the promotion mechanism based on Bi related heterostructures.

  17. Vibration Energy Harvester with Bi-stable Curved Beam Spring Offset by Gravitational Acceleration

    International Nuclear Information System (INIS)

    Yamamoto, Koki; Fujita, Takayuki; Kanda, Kensuke; Maenaka, Kazusuke; Badel, Adrien; Formosa, Fabien

    2015-01-01

    We developed MEMS bi-stable spring for vibration energy harvester (VEH), which consists of intrinsically curved shape spring and gravitational acceleration. By applying the gravitational acceleration, the curved beam is offset to the gravity direction. It will make more symmetrical bi-stable motion and the symmetry is improved from 3.3 to 65.4%. We proposed that the combination between curved beam and gravity acceleration for decreasing snap- through acceleration. From the analytical result, we investigate the combination can effective to use for decreasing of snap-through force. We also fabricated the prototype device by using MEMS fabrication process. The frequency response for horizontal direction and the acceleration response for vertical direction are measured. The acceleration response shows that the gravitational acceleration improves the symmetry of snap-through force. (paper)

  18. Correlation between modulation structure and electronic inhomogeneity on Pb-doped Bi-2212 single crystals

    International Nuclear Information System (INIS)

    Sugimoto, A.; Kashiwaya, S.; Eisaki, H.; Yamaguchi, H.; Oka, K.; Kashiwaya, H.; Tsuchiura, H.; Tanaka, Y.

    2005-01-01

    The correlation between nanometer-size electronic states and surface structure is investigated by scanning tunneling microscopy/spectroscopy (STM/S) on Pb-doped Bi 2-x Pb x Sr 2 CaCu2O 8+y (Pb-Bi-2212) single crystals. The advantage of the Pb-Bi-2212 samples is that the modulation structure can be totally or locally suppressed depending on the Pb contents and annealing conditions. The superconducting gap (Δ) distribution on modulated Pb-Bi-2212 samples showed the lack of correlation with modulation structure except a slight reduction of superconducting island size for the b-axis direction. On the other hand, the optimal doped Pb-Bi-2212 (x = 0.6) samples obtained by reduced-annealing showed totally non-modulated structure in topography, however, the spatial distribution of Δ still showed inhomogeneity of which features were quite similar to those of modulated samples. These results suggest that the modulation structure is not the dominant origin of inhomogeneity although it modifies the streaky Δ structure sub-dominantly. From the gap structure variation around the border of narrow gap and broad gap regions, a trend of the coexistence of two separated phases i.e., superconducting phase and pseudogap like phase, is detected

  19. Bismuth-boron multiple bonding in BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -}

    Energy Technology Data Exchange (ETDEWEB)

    Jian, Tian; Cheung, Ling Fung; Chen, Teng-Teng; Wang, Lai-Sheng [Department of Chemistry, Brown University, Providence, RI (United States)

    2017-08-01

    Despite its electron deficiency, boron is versatile in forming multiple bonds. Transition-metal-boron double bonding is known, but boron-metal triple bonds have been elusive. Two bismuth boron cluster anions, BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -}, containing triple and double B-Bi bonds are presented. The BiB{sub 2}O{sup -} and Bi{sub 2}B{sup -} clusters are produced by laser vaporization of a mixed B/Bi target and characterized by photoelectron spectroscopy and ab initio calculations. Well-resolved photoelectron spectra are obtained and interpreted with the help of ab initio calculations, which show that both species are linear. Chemical bonding analyses reveal that Bi forms triple and double bonds with boron in BiB{sub 2}O{sup -} ([Bi≡B-B≡O]{sup -}) and Bi{sub 2}B{sup -} ([Bi=B=Bi]{sup -}), respectively. The Bi-B double and triple bond strengths are calculated to be 3.21 and 4.70 eV, respectively. This is the first experimental observation of Bi-B double and triple bonds, opening the door to design main-group metal-boron complexes with multiple bonding. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Shock compression behavior of bi-material powder composites with disparate melting temperatures

    International Nuclear Information System (INIS)

    Sullivan, Kyle T.; Swift, Damian; Barham, Matthew; Stölken, James; Kuntz, Joshua; Kumar, Mukul

    2014-01-01

    Laser driven experiments were used to investigate the shock compression behavior of powder processed Bismuth/Tungsten (Bi/W) composite samples. The constituents provide different functionality to the composite behavior as Bi could be shock melted at the pressures attained in this work, while the W could not. Samples were prepared by uniaxial pressing, and the relative density was measured as a function of particle size, applied pressure, and composition for both hot and cold pressing conditions. This resulted in sample densities between 73% and 99% of the theoretical maximum density, and also noticeable differences in microstructure in the hot and cold pressed samples. The compression waves were generated with a 1.3 × 1.3 mm square spot directly onto the surface of the sample, using irradiances between 10 12 and 10 13  W/cm 2 , which resulted in calculated peak pressures between 50 and 150 GPa within a few micrometers. Sample recovery and post-mortem analysis revealed the formation of a crater on the laser drive surface, and the depth of this crater corresponded to the depth to which the Bi had been melted. The melt depth was found to be primarily a function of residual porosity and composition, and ranged from 167 to 528 μm. In general, a higher porosity led to a larger melt depth. Direct numerical simulations were performed, and indicated that the observed increase in melt depth for low-porosity samples could be largely attributed to increased heating associated with work done for pore collapse. However, the relative scaling was sensitive to composition, with low volume fraction Bi samples exhibiting a much stronger dependence on porosity than high Bi content samples. Select samples were repeated using an Al foil ablator, but there were no noticeable differences ensuring that the observed melting was indeed pressure-driven and was not a result of direct laser heating. The resultant microstructures and damage near the spall surface were also investigated

  1. A novel biosensor based on the direct electrochemistry of horseradish peroxidase immobilized in the three-dimensional flower-like Bi_2WO_6 microspheres

    International Nuclear Information System (INIS)

    Liu, Hui; Guo, Kai; Duan, Congyue; Chen, Xianjin; Zhu, Zhenfeng

    2016-01-01

    Three-dimensional flower-like Bi_2WO_6 microspheres (3D-Bi_2WO_6 MSs) have been synthesized through a simple hydrothermal method. The morphology and structure of 3D-Bi_2WO_6 MSs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The 3D-Bi_2WO_6 MSs subsequently were used to immobilize horseradish peroxidase (HRP) and fabricate a mediator-free biosensor for the detection of H_2O_2. Spectroscopic and electrochemical results reveal that 3D-Bi_2WO_6 MSs constitute an excellent immobilization matrix with biocompatibility for enzymes. Meanwhile, due to unique morphology of the flower-like microspheres, the direct electron transfer of HRP is facilitated and the prepared biosensors display good performances for the detection of H_2O_2 with a wide linear range, including two linear sections: 0.5–100 μM (R"2 = 0.9983) and 100–250 μM (R"2 = 0.9981), as well as an extremely low method detection limit of 0.18 μM. - Highlights: • 3D-Bi_2WO_6 microspheres are used to fabricate a mediator-free biosensor firstly. • The biosensor displays a wide linear range of 0.5–250 μM for H_2O_2. • The biosensor exhibits a low detection limit of 0.18 μM for H_2O_2.

  2. Using a Single VCSEL Source Employing OFDM Downstream Signal and Remodulated OOK Upstream Signal for Bi-directional Visible Light Communications.

    Science.gov (United States)

    Yeh, Chien-Hung; Wei, Liang-Yu; Chow, Chi-Wai

    2017-11-20

    In this work, we propose and demonstrate for the first time up to our knowledge, using a 682 nm visible vertical-cavity surface-emitting laser (VCSEL) applied in a bi-directional wavelength remodulated VLC system with a free space transmission distance of 3 m. To achieve a high VLC downstream traffic, spectral efficient orthogonal-frequency-division-multiplexing quadrature-amplitude-modulation (OFDM-QAM) with bit and power loading algorithms are applied on the VCSEL in the central office (CO). The OFDM downstream wavelength is remodulated by an acousto-optic modulator (AOM) with OOK modulation to produce the upstream traffic in the client side. Hence, only a single VCSEL laser is needed for the proposed bi-directional VLC system, achieving 10.6 Gbit/s OFDM downstream and 2 Mbit/s remodulated OOK upstream simultaneously. For the proposed system, as a single laser source with wavelength remodulation is used, the laser wavelength and temperature managements at the client side are not needed; and the whole system could be cost effective and energy efficient.

  3. Neutrino tri-bi-maximal mixing from a non-Abelian discrete family symmetry

    CERN Document Server

    Varzielas, I M; Ross, Graham G

    2007-01-01

    The observed neutrino mixing, having a near maximal atmospheric neutrino mixing angle and a large solar mixing angle, is close to tri-bi-maximal. We argue that this structure suggests a family symmetric origin in which the magnitude of the mixing angles are related to the existence of a discrete non-Abelian family symmetry. We construct a model in which the family symmetry is the non-Abelian discrete group $\\Delta(27)$, a subgroup of $SU(3)$ in which the tri-bi-maximal mixing directly follows from the vacuum structure enforced by the discrete symmetry. In addition to the lepton mixing angles, the model accounts for the observed quark and lepton masses and the CKM matrix. The structure is also consistent with an underlying stage of Grand Unification.

  4. Coordinated Operation of the Electricity and Natural Gas Systems with Bi-directional Energy Conversion

    DEFF Research Database (Denmark)

    Zeng, Qing; Zhang, Baohua; Fang, Jiakun

    2017-01-01

    A coordinated operation of the natural gas and electricity network with bi-directional energy conversion is expected to accommodate high penetration levels of renewables. This work focuses on the unified optimal operation of the integrated natural gas and electricity system considering the network...... constraints in both systems. An iterative method is proposed to deal with the nonlinearity in the proposed model. The models of the natural gas and power system are linearized in every iterative step. Simulation results demonstrate the effectiveness of the approach. Applicability of the proposed method...... is tested in the sample case. Finally, the effect of Power to Gas (P2G) on the daily economic dispatch is also investigated....

  5. Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO₃ thin films.

    Science.gov (United States)

    Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

    2013-05-22

    Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different.

  6. Pairing mechanism in Bi-O superconductors: A finite-size chain calculation

    International Nuclear Information System (INIS)

    Aligia, A.A.; Nunez Regueiro, M.D.; Gagliano, E.R.

    1989-01-01

    We have studied the pairing mechanism in BiO 3 systems by calculating the binding energy of a pair of holes in finite Bi-O chains, for parameters that simulate three-dimensional behavior. In agreement with previous results using perturbation theory in the hopping t, for covalent Bi-O binding and parameters for which the parent compound has a disproportionate ground state, pairing induced by the presence of biexcitons is obtained for sufficiently large interatomic Coulomb repulsion. The analysis of appropriate correlation functions shows a rapid metallization of the system as t and the number of holes increase. This fact shrinks the region of parameters for which the finite-size calculations can be trusted without further study. The same model for other parameters yields pairing in two other regimes: bipolaronic and magnetic excitonic

  7. Bi-Level Decentralized Active Power Control for Large-Scale Wind Farm Cluster

    DEFF Research Database (Denmark)

    Huang, Shengli; Wu, Qiuwei; Guo, Yifei

    2018-01-01

    This paper presents a bi-level decentralized active power control (DAPC) for a large-scale wind farm cluster, consisting of several wind farms for better active power dispatch. In the upper level, a distributed active power control scheme based on the distributed consensus is designed to achieve...... fair active power sharing among multiple wind farms, which generates the power reference for each wind farm. A distributed estimator is used to estimate the total available power of all wind farms. In the lower level, a centralized control scheme based on the Model Predictive Control (MPC) is proposed...... to regulate active power outputs of all wind turbines (WTs) within a wind farm, which reduces the fatigue loads of WTs while tracking the power reference obtained from the upper level control. A wind farm cluster with 8 wind farms and totally 160 WTs, was used to test the control performance of the proposed...

  8. DeBi: Discovering Differentially Expressed Biclusters using a Frequent Itemset Approach

    Directory of Open Access Journals (Sweden)

    Vingron Martin

    2011-06-01

    Full Text Available Abstract Background The analysis of massive high throughput data via clustering algorithms is very important for elucidating gene functions in biological systems. However, traditional clustering methods have several drawbacks. Biclustering overcomes these limitations by grouping genes and samples simultaneously. It discovers subsets of genes that are co-expressed in certain samples. Recent studies showed that biclustering has a great potential in detecting marker genes that are associated with certain tissues or diseases. Several biclustering algorithms have been proposed. However, it is still a challenge to find biclusters that are significant based on biological validation measures. Besides that, there is a need for a biclustering algorithm that is capable of analyzing very large datasets in reasonable time. Results Here we present a fast biclustering algorithm called DeBi (Differentially Expressed BIclusters. The algorithm is based on a well known data mining approach called frequent itemset. It discovers maximum size homogeneous biclusters in which each gene is strongly associated with a subset of samples. We evaluate the performance of DeBi on a yeast dataset, on synthetic datasets and on human datasets. Conclusions We demonstrate that the DeBi algorithm provides functionally more coherent gene sets compared to standard clustering or biclustering algorithms using biological validation measures such as Gene Ontology term and Transcription Factor Binding Site enrichment. We show that DeBi is a computationally efficient and powerful tool in analyzing large datasets. The method is also applicable on multiple gene expression datasets coming from different labs or platforms.

  9. Bi-Frequency Modulated Quasi-Resonant Converters: Theory and Applications

    Science.gov (United States)

    Zhang, Yuefeng

    1995-01-01

    To avoid the variable frequency operation of quasi -resonant converters, many soft-switching PWM converters have been proposed, all of them require an auxiliary switch, which will increase the cost and complexity of the power supply system. In this thesis, a new kind of technique for quasi -resonant converters has been proposed, which is called the bi-frequency modulation technique. By operating the quasi-resonant converters at two switching frequencies, this technique enables quasi-resonant converters to achieve the soft-switching, at fixed switching frequencies, without an auxiliary switch. The steady-state analysis of four commonly used quasi-resonant converters, namely, ZVS buck, ZCS buck, ZVS boost, and ZCS boost converter has been presented. Using the concepts of equivalent sources, equivalent sinks, and resonant tank, the large signal models of these four quasi -resonant converters were developed. Based on these models, the steady-state control characteristics of BFM ZVS buck, BFM ZCS buck, BFM ZVS boost, and BFM ZCS boost converter have been derived. The functional block and design consideration of the bi-frequency controller were presented, and one of the implementations of the bi-frequency controller was given. A complete design example has been presented. Both computer simulations and experimental results have verified that the bi-frequency modulated quasi-resonant converters can achieve soft-switching, at fixed switching frequencies, without an auxiliary switch. One of the application of bi-frequency modulation technique is for EMI reduction. The basic principle of using BFM technique for EMI reduction was introduced. Based on the spectral analysis, the EMI performances of the PWM, variable-frequency, and bi-frequency modulated control signals was evaluated, and the BFM control signals show the lowest EMI emission. The bi-frequency modulated technique has also been applied to the power factor correction. A BFM zero -current switching boost converter has

  10. Electric properties of a textured BiNaKTiO3 ceramic for energy harvesting system

    Science.gov (United States)

    Lim, D. H.; Song, T. K.; Lee, D. S.; Jeong, S. J.; Kim, Min-Soo; Song, Jae-Sung

    2012-01-01

    Piezoelectric ceramics with microstructural texturing were fabricated and evaluated to investigate their possibility for use in piezoelectric energy harvest devices in response to external mechanical impact. The microstructural evolution and properties of a Bi0.5(Na0.425K0.075) TiO3 (BNKT) ceramic material with platelike Bi4Ti3O12 (BiT) were investigated. The platelike Bi4Ti3O12 (BiT) was used as a template to induce grain growth under a proper heat treatment. The textured BNKTs were fabricated and heated at 1150 °C for 10 h. They exhibited -oriented large grains and improved of ferroelectric properties. The textured microstructure was due to the occurrence of grain growth around the templates. When subjected to a low stress of 0.8 MPa, the textured BNKT had a slightly larger voltage and power than the randomly-oriented BNKT. Meanwhile, when high stresses over 2 MPa were applied, the voltage and the power of the textured specimen were larger than those of the randomly-oriented specimen. The microstructure textured along the direction may contribute to the improved power generation.

  11. Electric properties of a textured BiNaKTiO3 ceramic for energy harvesting system

    International Nuclear Information System (INIS)

    Lim, D. H.; Song, T. K.; Lee, D. S.; Jeong, S. J.; Kim, M. S.; Song, J. S.

    2012-01-01

    Piezoelectric ceramics with microstructural texturing were fabricated and evaluated to investigate their possibility for use in piezoelectric energy harvest devices in response to external mechanical impact. The microstructural evolution and properties of a Bi 0.5 (Na 0.425 K 0.075 ) TiO 3 (BNKT) ceramic material with platelike Bi 4 Ti 3 O 12 (BiT) were investigated. The platelike Bi 4 Ti 3 O 12 (BiT) was used as a template to induce grain growth under a proper heat treatment. The textured BNKTs were fabricated and heated at 1150 .deg. C for 10 h. They exhibited -oriented large grains and improved of ferroelectric properties. The textured microstructure was due to the occurrence of grain growth around the templates. When subjected to a low stress of 0.8 MPa, the textured BNKT had a slightly larger voltage and power than the randomly-oriented BNKT. Meanwhile, when high stresses over 2 MPa were applied, the voltage and the power of the textured specimen were larger than those of the randomly-oriented specimen. The microstructure textured along the direction may contribute to the improved power generation.

  12. Flicker noise comparison of direct conversion mixers using Schottky and HBT dioderings in SiGe:C BiCMOS technology

    DEFF Research Database (Denmark)

    Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke; Tamborg, Kjeld

    2015-01-01

    In this paper, we present flicker noise measurements of two X-band direct conversion mixers implemented in a SiGe:C BiCMOS technology. Both mixers use a ring structure with either Schottky diodes or diode-connected HBTs for double balanced operation. The mixers are packaged in a metal casing on a...... circuit demonstrates a 1/f noise corner frequency around 10 kHz....

  13. The influence of the first non-singular stress terms on crack initiation direction in an orthotropic bi-material plate

    Czech Academy of Sciences Publication Activity Database

    Klusák, Jan; Hrstka, M.; Profant, T.; Krepl, Ondřej; Ševeček, O.; Kotoul, M.

    2014-01-01

    Roč. 71, JUN (2014), s. 67-75 ISSN 0167-8442 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068; GA ČR GA14-11234S Institutional support: RVO:68081723 Keywords : Bi-material notch * Crack initiation direction * Non-singular stress term * Generalized fracture mechanics * Path-independent integral Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.262, year: 2014

  14. Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film

    International Nuclear Information System (INIS)

    Gupta, Surbhi; Gupta, Vinay; Tomar, Monika; James, A. R.; Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar

    2014-01-01

    Multiferroic Bismuth Ferrite (BiFeO 3 ) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO 3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO 3 and Fe 2 O 3 to pure BiFeO 3 phase and, subsequently, to a mixture of BiFeO 3 and Bi 2 O 3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO 3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe 2 O 3 ). Deterioration in ferroic properties of BiFeO 3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO 3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm 2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO 3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO 3 thin films exhibiting the improved multiferroic properties.

  15. Comparison of ultraviolet Bi-directional Reflectance Distribution Function (BRDF) measurements of diffusers used in the calibration of the Total Ozone Mapping Spectrometer (TOMS)

    NARCIS (Netherlands)

    Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.

    2002-01-01

    The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those

  16. Bi-Directional Theta Modulation between the Septo-Hippocampal System and the Mammillary Area in Free-Moving Rats

    Directory of Open Access Journals (Sweden)

    Ming Ruan

    2017-09-01

    Full Text Available Hippocampal (HPC theta oscillations have long been linked to various functions of the brain. Many cortical and subcortical areas that also exhibit theta oscillations have been linked to functional circuits with the hippocampus on the basis of coupled activities at theta frequencies. We examine, in freely moving rats, the characteristics of diencephalic theta local field potentials (LFPs recorded in the supramammillary/mammillary (SuM/MM areas that are bi-directionally connected to the HPC through the septal complex. Using partial directed coherence (PDC, we find support for previous suggestions that SuM modulates HPC theta at higher frequencies. We find weak separation of SuM and MM by dominant theta frequency recorded locally. Contrary to oscillatory cell activities under anesthesia where SuM is insensitive, but MM is sensitive to medial septal (MS inactivation, theta LFPs persisted and became indistinguishable after MS-inactivation. However, MS-inactivation attenuated SuM/MM theta power, while increasing the frequency of SuM/MM theta. MS-inactivation also reduced root mean squared power in both HPC and SuM/MM equally, but reduced theta power differentially in the time domain. We provide converging evidence that SuM is preferentially involved in coding HPC theta at higher frequencies, and that the MS-HPC circuit normally imposes a frequency-limiting modulation over the SuM/MM area as suggested by cell-based recordings in anesthetized animals. In addition, we provide evidence that the postulated SuM-MS-HPC-MM circuit is under complex bi-directional control, rather than SuM and MM having roles as unidirectional relays in the network.

  17. Sodium citrate-assisted anion exchange strategy for construction of Bi2O2CO3/BiOI photocatalysts

    International Nuclear Information System (INIS)

    Song, Peng-Yuan; Xu, Ming; Zhang, Wei-De

    2015-01-01

    Highlights: • Heterostructured Bi 2 O 2 CO 3 /BiOI microspheres were prepared via anion exchange. • Sodium citrate-assisted anion exchange for construction of composite photocatalysts. • Bi 2 O 2 CO 3 /BiOI composites show high visible light photocatalytic activity. - Abstract: Bi 2 O 2 CO 3 /BiOI heterojuncted photocatalysts were constructed through a facile partial anion exchange strategy starting from BiOI microspheres and urea with the assistance of sodium citrate. The content of Bi 2 O 2 CO 3 in the catalysts was regulated by modulating the amount of urea as a precursor, which was decomposed to generate CO 3 2− in the hydrothermal process. Citrate anion plays a key role in controlling the morphology and composition of the products. The Bi 2 O 2 CO 3 /BiOI catalysts display much higher photocatalytic activity than pure BiOI and Bi 2 O 2 CO 3 towards the degradation of rhodamine B (RhB) and bisphenol A (BPA). The enhancement of photocatalytic activity of the heterojuncted catalysts is attributed to the formation of p–n junction between p-BiOI and n-Bi 2 O 2 CO 3 , which is favorable for retarding the recombination of photoinduced electron-hole pairs. Moreover, the holes are demonstrated to be the main active species for the degradation of RhB and BPA

  18. Delay-dependent exponential stability analysis of bi-directional associative memory neural networks with time delay: an LMI approach

    International Nuclear Information System (INIS)

    Li Chuandong; Liao Xiaofeng; Zhang Rong

    2005-01-01

    For bi-directional associative memory (BAM) neural networks (NNs) with different constant or time-varying delays, the problems of determining the exponential stability and estimating the exponential convergence rate are investigated in this paper. An approach combining the Lyapunov-Krasovskii functional with the linear matrix inequality (LMI) is taken to study the problems, which provide bounds on the interconnection matrix and the activation functions, so as to guarantee the system's exponential stability. Some criteria for the exponential stability, which give information on the delay-dependent property, are derived. The results obtained in this paper provide one more set of easily verified guidelines for determining the exponential stability of delayed BAM (DBAM) neural networks, which are less conservative and less restrictive than the ones reported so far in the literature. Some typical examples are presented to show the application of the criteria obtained in this paper

  19. Sample-size resonance, ferromagnetic resonance and magneto-permittivity resonance in multiferroic nano-BiFeO3/paraffin composites at room temperature

    International Nuclear Information System (INIS)

    Wang, Lei; Li, Zhenyu; Jiang, Jia; An, Taiyu; Qin, Hongwei; Hu, Jifan

    2017-01-01

    In the present work, we demonstrate that ferromagnetic resonance and magneto-permittivity resonance can be observed in appropriate microwave frequencies at room temperature for multiferroic nano-BiFeO 3 /paraffin composite sample with an appropriate sample-thickness (such as 2 mm). Ferromagnetic resonance originates from the room-temperature weak ferromagnetism of nano-BiFeO 3 . The observed magneto-permittivity resonance in multiferroic nano-BiFeO 3 is connected with the dynamic magnetoelectric coupling through Dzyaloshinskii–Moriya (DM) magnetoelectric interaction or the combination of magnetostriction and piezoelectric effects. In addition, we experimentally observed the resonance of negative imaginary permeability for nano BiFeO 3 /paraffin toroidal samples with longer sample thicknesses D=3.7 and 4.9 mm. Such resonance of negative imaginary permeability belongs to sample-size resonance. - Highlights: • Nano-BiFeO 3 /paraffin composite shows a ferromagnetic resonance. • Nano-BiFeO 3 /paraffin composite shows a magneto-permittivity resonance. • Resonance of negative imaginary permeability in BiFeO 3 is a sample-size resonance. • Nano-BiFeO 3 /paraffin composite with large thickness shows a sample-size resonance.

  20. First-principles approach to the dynamic magnetoelectric couplings for the non-reciprocal directional dichroism in BiFeO3

    International Nuclear Information System (INIS)

    Lee, Jun Hee; Fishman, Randy S; Kézsmáki, István

    2016-01-01

    Due to the complicated magnetic and crystallographic structures of BiFeO 3 , its magnetoelectric (ME) couplings and microscopic model Hamiltonian remain poorly understood. By employing a first-principles approach, we uncover all possible ME couplings associated with the spin-current (SC) and exchange-striction (ES) polarizations, and construct an appropriate Hamiltonian for the long-range spin-cycloid in BiFeO 3 . First-principles calculations are used to understand the microscopic origins of the ME couplings. We find that inversion symmetries broken by ferroelectric and antiferroelectric distortions induce the SC and the ES polarizations, which cooperatively produce the dynamic ME effects in BiFeO 3 . A model motivated by first principles reproduces the absorption difference of counter-propagating light beams called non-reciprocal directional dichroism. The current paper focuses on the spin-driven (SD) polarizations produced by a dynamic electric field, i.e. the dynamic ME couplings. Due to the inertial properties of Fe, the dynamic SD polarizations differ significantly from the static SD polarizations. Our systematic approach can be generally applied to any multiferroic material, laying the foundation for revealing hidden ME couplings on the atomic scale and for exploiting optical ME effects in the next generation of technological devices such as optical diodes. (paper)

  1. One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres with enhanced photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Lingling [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Luo, Zhijun, E-mail: lzj@ujs.edu.cn [School of the Environment, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 (China); Tang, Chao [Maple Leaf International High School, Zhenjiang 212013 (China)

    2013-11-15

    Graphical abstract: Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core–shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs). Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation. - Highlights: • One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres. • Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@CRCSs. • Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits enhanced photocatalytic activity under visible light irradiation. - Abstract: Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core-shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs) have been synthesized via a one-step method. The core–shell nanosturctures of the as-prepared samples were confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Raman spectroscopy. The formation of Bi@Bi{sub 2}O{sub 3}@CRCSs core–shell nanosturctures should attribute to the synergetic roles of different functional groups of sodium gluconate. Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation (λ > 420 nm) and shows an O{sub 2}-dependent feature. According to trapping experiments of radicals and holes, hydroxyl radicals were not the main active oxidative species in the photocatalytic degradation of MB, but O{sub 2}·{sup −} are the main active oxidative species.

  2. Label-Free Biosensors Based on Bimodal Waveguide (BiMW) Interferometers.

    Science.gov (United States)

    Herranz, Sonia; Gavela, Adrián Fernández; Lechuga, Laura M

    2017-01-01

    The bimodal waveguide (BiMW) sensor is a novel common path interferometric transducer based on the evanescent field detection principle, which in combination with a bio-recognition element allows the direct detection of biomolecular interactions in a label-free scheme. Due to its inherent high sensitivity it has great potential to become a powerful analytical tool for monitoring substances of interest in areas such as environmental control, medical diagnostics and food safety, among others. The BiMW sensor is fabricated using standard silicon-based technology allowing cost-effective production, and meeting the requirements of portability and disposability necessary for implementation in a point-of-care (POC) setting.In this chapter we describe the design and fabrication of the BiMW transducer, as well as its application for bio-sensing purposes. We show as an example the biosensor capabilities two different applications: (1) the immunodetection of Irgarol 1051 biocide useful in the environmental field, and (2) the detection of human growth hormone as used in clinical diagnostics. The detection is performed in real time by monitoring changes in the intensity pattern of light exiting the BiMW transducer resulting from antigen-antibody interactions on the surface of the sensor.

  3. Photoelectrochemical properties of TiO2 Nanotube Arrays Modified with BiOCl nanosheets

    International Nuclear Information System (INIS)

    Liu, Haipeng; Xu, Guangqing; Wang, Jinwen; Lv, Jun; Zheng, Zhixiang; Wu, Yucheng

    2014-01-01

    Highlights: • BiOCl were deposited on TiO2 NTAs by sequential chemical bath deposition. • BiOCl can decrease background photocurrent and increase current response. • High sensitivity BiOCl/TiO2 is due to the direct oxidation of organics on BiOCl. - Abstract: BiOCl nanosheets were deposited on anodized TiO 2 nanotube arrays (NTAs) by sequential chemical bath deposition method to get BiOCl/TiO 2 NTAs for photoelectrochemical detection of organic compounds (represented by glucose). The structures, elemental components and morphologies of TiO 2 and BiOCl/TiO 2 NTAs were characterized by using X-ray diffraction diffractometer, scanning electron microscope and transmission electron microscope. The photoelectrochemical behaviors of TiO 2 and BiOCl/TiO 2 NTAs in the buffer and glucose solutions were measured by cyclic votammetry and amperometry with different optical powers. The modification of BiOCl nanosheets on TiO 2 NTAs decreases the photocurrents of TiO 2 NTAs in the buffer solution and increases the current response to glucose. Both of the background photocurrent decrease and current response increase are benefit for photoelectrochemical detection of organic compounds. When glucose was used as the target organic compound, the optimized BiOCl/TiO 2 NTAs sensor achieved a sensitivity of 0.327 μA/μM (0.417 μA·cm −2 ·μM −1 ), linear range from 0 to 1300 μM and calculated detection limit of 5.7 μM. Mechanisms of BiOCl modification were studied by measuring the optical absorption and hydroxyl radical HO· productivity. The transfer of holes from TiO 2 to BiOCl and the direct oxidation of organic compounds on BiOCl nanosheets led to the decrease of background photocurrent (lower reaction rate of water splitting on BiOCl nanosheets) and the increase of current response to organic compounds (higher reaction rate of direct oxidation of organic compounds)

  4. Preparation and characterization of PtRu/C, PtBi/C, PtRuBi/C electrocatalysts for direct electro-oxidation of ethanol in PEM fuels cells using the method of reduction by sodium borohydride

    International Nuclear Information System (INIS)

    Brandalise, Michele

    2010-01-01

    Pt/C, PtBi/C, PtRu/C and PtRuBi/C electrocatalysts were prepared by a borohydride reduction methodology and tested for ethanol oxidation. This methodology consists in mix a solution with sodium hydroxide and sodium borohydride to a mixture containing water/isopropyl alcohol, metallic precursors and the Vulcan XC 72 carbon support. It was studied the addition method of borohydride (drop by drop addition or rapid addition). The obtained electrocatalysts were characterized by energy dispersive X ray spectroscopy (EDX), thermogravimetric analysis (TGA), X ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry. The ethanol electro-oxidation was studied by cyclic voltammetry and chronoamperometry using the thin porous coating technique. The electrocatalysts were tested in real conditions of operation by unit cell tests. The stability of PtRuBi/C electrocatalysts was evaluated by cyclic voltammetry, chronoamperometry using the ultra-thin porous coating technique and ring-disk electrode. The PtRuBi/C electro catalyst apparently presented a good performance for ethanol electro-oxidation but experimental evidences showed accentuated bismuth dissolution. (author)

  5. In situ grown hierarchical 50%BiOCl/BiOI hollow flowerlike microspheres on reduced graphene oxide nanosheets for enhanced visible-light photocatalytic degradation of rhodamine B

    Science.gov (United States)

    Su, Xiangde; Yang, Jinjin; Yu, Xiang; Zhu, Yi; Zhang, Yuanming

    2018-03-01

    50%BiOCl/BiOI/reduced graphene oxide (50%BiOCl/BiOI/rGO) composite photocatalyst was synthesized successfully by a facile one-step solvothermal route in this work. Reduction of graphene oxide (GO) took place in the process of solvothermal reaction and a new Bi-C bond between rGO and 50%BiOCl/BiOI was formed. The introduction of rGO affected the morphology of 50%BiOCl/BiOI, resulting in the transformation of 50%BiOCl/BiOI from solid microspheres to hollow microspheres. Both the introduction of rGO and formation of 50%BiOCl/BiOI hollow microspheres can facilitate the light absorption. The strong interaction between 50%BiOCl/BiOI and rGO and the electrical conductivity of rGO greatly improved the effective separation of photogenerated carriers. Hence, GOB-5 demonstrated the highest photocatalytic activity which was over twice of the pristine 50%BiOCl/BiOI in the presence of visible light. Mechanism study revealed that 50%BiOCl/BiOI generated electrons and holes in the presence of visible light, and holes together with rad O2- generated from reduction of O2 by electrons degraded the pollutant directly. Overall, this work provides an excellent reference to the synthesis of chemically bonded BiOX/BiOY (X, Y = Cl, Br, I)/rGO nanocomposite and helps to promote their applications in environmental protection and photoelectric conversion.

  6. Photocatalytic activity of Bi{sub 2}WO{sub 6}/Bi{sub 2}S{sub 3} heterojunctions: the facilitation of exposed facets of Bi{sub 2}WO{sub 6} substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Long [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China); Wang, Yufei [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); Shen, Huidong; Zhang, Yu [School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China); Li, Jian [School of Chemistry and Chemical Engineering, Yulin University, Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization, Yulin 71900 (China); Wang, Danjun, E-mail: yulyanlong@aliyun.com [School of Chemistry and Chemical Engineering, Yan’an University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan’an 716000 (China)

    2017-01-30

    Highlights: • Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} hybrids with exposed (020) Bi{sub 2}WO{sub 6} facets have been synthesized. • X-ray photoelectron spectroscopy reveals that a small amount of Bi{sub 2}S{sub 3} was formed. • The enhanced photoactivity of hybrids is due to heterojunction and (020) facets. • A possible photocatalytic degradation mechanism is proposed. - Abstract: Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} hybrid architectures with exposed (020) Bi{sub 2}WO{sub 6} facets have been synthesized via a controlled anion exchange approach. X-ray photoelectron spectroscopy (XPS) reveals that a small amount of Bi{sub 2}S{sub 3} was formed on the surface of Bi{sub 2}WO{sub 6} during the anion exchange process, thus leading to the transformation from the Bi{sub 2}WO{sub 6} to Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}. A rhodamine B (RhB) aqueous solution was chosen as model organic pollutants to evaluate the photocatalytic activities of the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6} catalysts. Under visible light irradiation, the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}-TAA displayed the excellent visible light photoactivities compared with pure Bi{sub 2}S{sub 3}, Bi{sub 2}WO{sub 6} and other composite photocatalysts. The efficient photocatalytic activity of the Bi{sub 2}S{sub 3}/Bi{sub 2}WO{sub 6}-TAA composite microspheres was ascribed to the constructed heterojunctions and the inner electric field caused by the exposed (020) Bi{sub 2}WO{sub 6} facets. Active species trapping experiments revealed that h{sup +} and O{sub 2}·{sup −} are the main active species in the photocatalytic process. Furthermore, the as-obtained photocatalysts showed good photocatalytic activity after four recycles. The results presented in this study provide a new concept for the rational design and development of highly efficient photocatalysts.

  7. Bi-directional Exchange: the Cornerstone of Globally Focused Social Work.

    Science.gov (United States)

    Parker, Gary; Ali, Samira; Ringell, Kassia; McKay, Mary

    2014-03-01

    Social work holds a unique place relative to other professions in that it prioritizes the elimination of human suffering as its primary goal. The roots of the profession are firmly planted in Western theories, historically and culturally specific perspectives, and knowledge. History has repeatedly demonstrated an association between the arrival of Westerners and the subsequent control of natural resources. Some argue that the development of global social work practice has serious pitfalls, including diverting needed resources away from local contexts and inadvertently spreading western world-views, paradigms and practices. However, the social work profession is uniquely positioned to offer expertise and collaborate with those experiencing the serious consequences of social inequity and the dearth of economic and social resources locally and across the globe. Grounded in anti-oppressive theory, guided by the difficult, yet acute awareness of western privilege and racism, and drawing from social/collective action and collaborative paradigms, a bi-directional exchange and action are detailed as the foundations for globally focused social work. The skills and knowledge base for global social work are essential as populations locally and worldwide are impacted by a global economic system that innately increases serious social inequity. Comprehensive training and preparation for globally focused social work, critical to successful engagement in global practice are outlined.

  8. Sample-size resonance, ferromagnetic resonance and magneto-permittivity resonance in multiferroic nano-BiFeO{sub 3}/paraffin composites at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lei; Li, Zhenyu; Jiang, Jia; An, Taiyu; Qin, Hongwei; Hu, Jifan, E-mail: hujf@sdu.edu.cn

    2017-01-01

    In the present work, we demonstrate that ferromagnetic resonance and magneto-permittivity resonance can be observed in appropriate microwave frequencies at room temperature for multiferroic nano-BiFeO{sub 3}/paraffin composite sample with an appropriate sample-thickness (such as 2 mm). Ferromagnetic resonance originates from the room-temperature weak ferromagnetism of nano-BiFeO{sub 3}. The observed magneto-permittivity resonance in multiferroic nano-BiFeO{sub 3} is connected with the dynamic magnetoelectric coupling through Dzyaloshinskii–Moriya (DM) magnetoelectric interaction or the combination of magnetostriction and piezoelectric effects. In addition, we experimentally observed the resonance of negative imaginary permeability for nano BiFeO{sub 3}/paraffin toroidal samples with longer sample thicknesses D=3.7 and 4.9 mm. Such resonance of negative imaginary permeability belongs to sample-size resonance. - Highlights: • Nano-BiFeO{sub 3}/paraffin composite shows a ferromagnetic resonance. • Nano-BiFeO{sub 3}/paraffin composite shows a magneto-permittivity resonance. • Resonance of negative imaginary permeability in BiFeO{sub 3} is a sample-size resonance. • Nano-BiFeO{sub 3}/paraffin composite with large thickness shows a sample-size resonance.

  9. Growth and characterization of Bi2Se3 crystals by chemical vapor transport

    Directory of Open Access Journals (Sweden)

    W. H. Jiao

    2012-06-01

    Full Text Available Regularly-shaped high-quality Bi2Se3 crystals were grown by a chemical vapor transport using iodine as the transport agent. In addition to exhibiting a characteristic Dirac cone for a topological insulator, the Bi2Se3 crystals show some outstanding properties including additional crystallographic surfaces, large residual resistance ratio (∼10, and high mobility (∼8000 cm2·V−1·s−1. The low-temperature resistivity abnormally increases with applying pressures up to 1.7 GPa, and no superconductivity was observed down to 0.4 K.

  10. Photocatalytic perfermance of sandwich-like BiVO_4 sheets by microwave assisted synthesis

    International Nuclear Information System (INIS)

    Liu, Suqin; Tang, Huiling; Zhou, Huan; Dai, Gaopeng; Wang, Wanqiang

    2017-01-01

    Graphical abstract: Sandwich-like BiVO_4 sheets were successfully synthesized via a facile microwave-assisted method. The as-prepared samples exhibit a high activity for the degradation of methyl orange under visible light irradiation. - Highlights: • Sandwich-like BiVO_4 sheets were synthesized by a facile microwave-assisted method. • The presence of PEG-10000 plays a critical role in the formation of BiVO_4 sheets. • Ostwald ripening is the primary driving force for the formation of sandwich-like BiVO_4. • The sandwich-like BiVO_4 sheets exhibit a high visible-light photocatalytic activity. - Abstract: Sandwich-like BiVO_4 sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG-10000) using a facile microwave-assisted method. The as-prepared samples were characterized by scanning electron microscopy, N_2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy. The results show that the presence of PEG-10000 plays a critical role in the formation of BiVO_4 sheets, and Ostwald ripening is the primary driving force for the formation of sandwich-like structures. The sandwich-like BiVO_4 sheets exhibit a high activity for the degradation of methyl orange under visible light irradiation (λ ≥ 420 nm). The enhancement of photocatalytic activity of sandwich-like BiVO_4 sheets can be attributed to its large surface area over the irregular BiVO_4 particles.

  11. Synthesis and characterization of Bi2S3 composite nanoparticles with high X-ray absorption

    International Nuclear Information System (INIS)

    Huang, Huan-Huan; Chen, Jun; Meng, Yuan-Zheng; Yang, Xiao-Quan; Zhang, Ming-Zhen; Yu, Yong; Ma, Zhi-Ya; Zhao, Yuan-Di

    2013-01-01

    Graphical abstract: - Highlights: • Uniform Bi 2 S 3 nanorods were prepared via a hot injection method. • Bi 2 S 3 nanorods were coated with TEOS and PEG for surface modification. • CT images of Bi 2 S 3 @SiO 2 -PEG are much higher than clinical iobitridol when they have the same concentration. • Cellular toxicity of Bi 2 S 3 @SiO 2 -PEG is low when the probes were directly in contact with tissue fluid. - Abstract: Owing to the high X-ray absorption, Bi 2 S 3 nanocrystals are widely used as CT contrast agents. Here, we prepared uniform Bi 2 S 3 nanorods via a hot injection method using bismuth (III) chloride, sulfur and oleyl amine. The resulting nanocrystals were coated with tetraethylorthosilicate (TEOS) and 2-[methoxy(polyethyleneoxy)propyl]yrimethoxysilane (PEG-silane) for the biological utility. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that the Bi 2 S 3 nanorods had an orthorhombic structure with the length of 14 nm and the diameter of 7 nm, respectively. Composite nanoparticles (0.0226 M) gave a CT number at 550 (HU), which was higher than that of the commercial available iobitridol CT contrast agent. Furthermore, cell experiments revealed that Bi 2 S 3 composite nanoparticles had a low cytotoxicity with a concentration up to 0.01 M of Bi for 24 h

  12. Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO{sub 3} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Surbhi; Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi (India); Tomar, Monika [Department of Physics, Miranda Housea, University of Delhi, Delhi (India); James, A. R. [Defence Metallurgical Research Laboratory, Hyderabad (India); Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar [Department of Electrical and Computer Engineering, College of Engineering, University of Texas at SanAntonio, San Antonio 78249 (United States)

    2014-06-21

    Multiferroic Bismuth Ferrite (BiFeO{sub 3}) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO{sub 3} thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO{sub 3} and Fe{sub 2}O{sub 3} to pure BiFeO{sub 3} phase and, subsequently, to a mixture of BiFeO{sub 3} and Bi{sub 2}O{sub 3} with increase in the concentration of excess Bi from 0% to 15%. BiFeO{sub 3} thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe{sub 2}O{sub 3}). Deterioration in ferroic properties of BiFeO{sub 3} thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO{sub 3} thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm{sup 2} and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO{sub 3} thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO{sub 3} thin films exhibiting the improved multiferroic properties.

  13. Large Tc depression at low angle [100] tilt grain boundaries in bulk Bi2Sr2CaCu2O8+δ bicrystals

    International Nuclear Information System (INIS)

    Li, Q.; Tsay, Y.N.; Zhu, Y.; Suenaga, M.; Gu, G.D.; Koshizuka, N.

    1997-01-01

    Large depression of T c at 7 degree [100] tilt grain boundaries was observed in bulk Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) bicrystals by measuring the zero-field electrical transport properties of the grain boundaries and the constituent single crystals over an extended range of currents and voltages. The T c -depressed region was determined to be around 20 nm, comparable to the width of the strain field associated with the observed array of grain-boundary dislocations. Superconducting coupling of the grain boundaries increases sharply as temperature decreases below the grain-boundary T c congruent 68 K. copyright 1997 American Institute of Physics

  14. Magnetic Doping and Kondo Effect in Bi 2 Se 3 Nanoribbons

    KAUST Repository

    Cha, Judy J.; Williams, James R.; Kong, Desheng; Meister, Stefan; Peng, Hailin; Bestwick, Andrew J.; Gallagher, Patrick; Goldhaber-Gordon, David; Cui, Yi

    2010-01-01

    A simple surface band structure and a large bulk band gap have allowed Bi2Se3 to become a reference material for the newly discovered three-dimensional topological insulators, which exhibit topologically protected conducting surface states that reside inside the bulk band gap. Studying topological insulators such as Bi2Se3 in nanostructures is advantageous because of the high surfaceto-volume ratio, which enhances effects from the surface states; recently reported Aharonov-Bohm oscillation in topological insulator nanoribbons by some of us is a good example. Theoretically, introducing magnetic impurities in topological insulators is predicted to open a small gap in the surface states by breaking time-reversal symmetry. Here, we present synthesis of magnetically doped Bi 2Se3 nanoribbons by vapor-liquid-solid growth using magnetic metal thin films as catalysts. Although the doping concentration is less than ∼2 %. low-temperature transport measurements of the Fe-doped Bi2Se3 nanoribbon devices show a clear Kondo effect at temperatures below 30 K, confirming the presence of magnetic impurities in the Bi2Se3 nanoribbons. The capability to dope topological insulator nanostructures magnetically opens up exciting opportunities for spintronics. © 2010 American Chemical Society.

  15. Magnetic Doping and Kondo Effect in Bi 2 Se 3 Nanoribbons

    KAUST Repository

    Cha, Judy J.

    2010-03-10

    A simple surface band structure and a large bulk band gap have allowed Bi2Se3 to become a reference material for the newly discovered three-dimensional topological insulators, which exhibit topologically protected conducting surface states that reside inside the bulk band gap. Studying topological insulators such as Bi2Se3 in nanostructures is advantageous because of the high surfaceto-volume ratio, which enhances effects from the surface states; recently reported Aharonov-Bohm oscillation in topological insulator nanoribbons by some of us is a good example. Theoretically, introducing magnetic impurities in topological insulators is predicted to open a small gap in the surface states by breaking time-reversal symmetry. Here, we present synthesis of magnetically doped Bi 2Se3 nanoribbons by vapor-liquid-solid growth using magnetic metal thin films as catalysts. Although the doping concentration is less than ∼2 %. low-temperature transport measurements of the Fe-doped Bi2Se3 nanoribbon devices show a clear Kondo effect at temperatures below 30 K, confirming the presence of magnetic impurities in the Bi2Se3 nanoribbons. The capability to dope topological insulator nanostructures magnetically opens up exciting opportunities for spintronics. © 2010 American Chemical Society.

  16. Effect of Working Fluids on the Thermal Performance of a Bi-directional Solar Thermodiode

    International Nuclear Information System (INIS)

    Ko, Yung Joo

    2008-02-01

    An excessive use of fossil fuel leads to the limitation of coal deposits and carbon dioxide accumulation that accelerates the global warming, so the international environment regulation becomes more strict to control the greenhouse gas emission. Many researches are being made on alternative energy development to cut down fossil fuel and to decrease carbon dioxide. During the last decade, there have been active tries to utilize the solar energy that is unlimited and clean . The application of solar energy to heating and cooling of the building has much improved the economical efficiency and function with the development of high-technology materials, and it is not rare to find the recently built houses and commercial buildings equipped with solar energy systems. In particular, the advanced countries such as USA and Japan attempt the remarkable reduction of energy consumption in heating and cooling of buildings. For this, they are searching for the more effective application of various alternative energies including the solar energy. In addition, they are trying to realize the distinct zero energy conception by applying the new techniques and materials to the existing buildings. In developing the new techniques of solar energy application to heating and cooling system, the economic problems hire to be addressed, The typical problems encountered in applying the solar energy are insufficient design concept for HVAC(heating, ventilation, and air conditioning) system and low reliability, Further, the economical efficiency of the solar energy is still low to compete with the oil, and there are many limits on the realization of the actual system in a building, e.g. spatial alignments and exterior appearances. The purpose of this study is to find the improved method to increase the heat transfer efficiency of the solar energy system that are to be installed in houses and commercial buildings. For this, a series of experiments using the bi-directional thermo diode system

  17. Quantum interference effects in [Co/Bi]n thin films

    Directory of Open Access Journals (Sweden)

    Athanasopoulos P.

    2014-07-01

    Full Text Available Magnetoconductivity (MC, Δσ(Β, and Hall coefficient, RH(B, measurements have been performed in polycrystalline thin films of Bi(15nm, Bi(10nm/Co(1nm/Bi(10nm trilayer and [Co(0.7nm/Bi(2nm]10 multilayer, grown by magnetron scattering. The temperature dependence of RH(B curves reveal the existence of a second conduction channel below 250K, that can be assigned to surface states. MC measurements between ±0.4T show at 5K an interplay between weak-antilocalization (WAL in Bi and Bi/Co/Bi films and weal-localization (WL in [Co/Bi]10 multilayer.

  18. Synthesis of Zn{sup 2+} doped BiOCl hierarchical nanostructures and their exceptional visible light photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wen Ting [Department of Chemistry, Fujian Normal University, Fuzhou 350007 (China); Huang, Wan Zhen; Zhou, Huan [Research Center of Analysis and Measurement, Zhejiang University of Technology, Hangzhou 310014 (China); Yin, Hao Yong [Institute of Environmental Science and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zheng, Yi Fan [Research Center of Analysis and Measurement, Zhejiang University of Technology, Hangzhou 310014 (China); Song, Xu Chun, E-mail: songxuchunfj@163.com [Department of Chemistry, Fujian Normal University, Fuzhou 350007 (China)

    2015-07-25

    Highlights: • Hierarchical-structured Zn-doped BiOCl were prepared by a facile solvothermal method. • The Zn-doped BiOCl showed higher photocatalytic ability than other BiOCl materials. • The effects of Zn-doping contents on the photocatalytic activity were discussed. • Repetitive tests implied the good stability of the Zn-doped BiOCl photocatalyst. - Abstract: In this study, BiOCl doped with different contents of zinc were successfully prepared via a facile ethylene glycol (EG)-assisted solvothermal process at 160 °C for 12 h. The as-synthesized samples were characterized in details by X-ray powder diffraction (XRD), energy dispersive X-ray analysis (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), UV–vis diffuse reflectance spectra (UV–vis DRS) and Brunauer Emmet Teller (BET) measurement. The photocatalytic performances were evaluated by the photocatalytic degradation of Rhodamine B (RhB) under visible light irradiation. The results showed that Zn doping did not change the morphologies and particle sizes of BiOCl. However, it had an obvious effect on the photocurrent and BET surface area of BiOCl and accordingly the photocatalytic performance of BiOCl was greatly improved. The Zn-doped BiOCl with R{sub Zn} = 0.07 showed the highest photocatalytic activities with almost all of the RhB decomposed in 8 min. Moreover, repetitive tests imply the good recyclability and stability of the catalysts. The enhanced photocatalytic activity was largely ascribed to the efficient separation of photogenerated electron–hole pairs and high BET surface area of the catalysts. In addition, a possible mechanism on basis of the experimental results was discussed.

  19. Overexpression of BiP in tobacco alleviates endoplasmic reticulum stress

    NARCIS (Netherlands)

    Leborgne-Castel, N.; Jelitto- Dooren, E.P.W.M. van; Crofts, A.J.; Denecke, J.

    1999-01-01

    To study the role of the lumenal binding protein (BiP) in the transport and secretion of proteins, we have produced plants with altered BiP levels. Transgenic plants overexpressing BiP showed dramatically increased BiP mRNA levels but only a modest increase in BiP protein levels. The presence of

  20. Spectroscopic evidence of two-dimensional character of the 90 K Bi2(Sr,La,Ca)3Cu2O8 superconductors

    International Nuclear Information System (INIS)

    Lindberg, P.A.P.; Shen, Z.; Wells, B.O.; Dessau, D.S.; Borg, A.; Lindau, I.; Spicer, W.E.; Mitzi, D.B.; Kapitulnik, A.

    1989-01-01

    Polarization-dependent angle-resolved photoemission experiments in the constant final state mode (absorption measurements) were performed on single crystals of the Bi-based 2212 material using synchrotron radiation in the photon energy range 10--40 eV. Evidence of polarization-dependent transitions due to Bi 5d→6p, Sr 4p→4d, and Ca 3p→3d excitations is observed. The data show that the electronic charge is highly localized to the layers of the crystal structure, thus providing a direct spectroscopic confirmation of the two-dimensional nature of these types of materials. Polarization-sensitive absorption signals at 14--15 eV attributed to Bi 6s→6p transitions show that the density of states (DOS) of the Bi 6p z holes peaks at about 0.7 eV higher energy than the DOS of the Bi 6p x,y holes

  1. Design and Fabrication of Multifunctional Portable Bi2Te3-Based Thermoelectric Camping Lamp

    Science.gov (United States)

    Zhou, Yi; Li, Gongping

    2018-05-01

    Camping lamps have been widely used in the lighting, power supply, and intelligent electronic equipment fields. However, applications of traditional chemical and solar camping lamps are largely limited by the physical size of the source and operating conditions. A new prototype multifunctional portable Bi2Te3-based thermoelectric camping lamp (TECL) has been designed and fabricated. Ten parallel light-emitting diodes were lit directly by a Bi2Te3-based thermoelectric generator (TEG). The highest short-circuit current of 0.38 A and open-circuit voltage of 4.2 V were obtained at temperature difference of 115 K. This TECL is attractive for use in multifunctional and extreme applications as it integrates a portable heat source, high-performance TEG, and power management unit.

  2. Chemical bath deposition of Cu{sub 3}BiS{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, S.G., E-mail: deshmukhpradyumn@gmail.com; Vipul, Kheraj, E-mail: vipulkheraj@gmail.com [Department of Applied Physics, Sardar Vallabhbhai National Institute of Technology, Ichchhanath, Surat (India); Panchal, A.K. [Department of Electrical Engineering, Sardar Vallabhbhai National Institute of Technology, Ichchhanath, Surat (India)

    2016-05-06

    First time, copper bismuth sulfide (Cu{sub 3}BiS{sub 3}) thin films were synthesized on the glass substrate using simple, low-cost chemical bath deposition (CBD) technique. The synthesized parameters such as temperature of bath, pH and concentration of precursors were optimized for the deposition of uniform, well adherent Cu{sub 3}BiS{sub 3} thin films. The optical, surface morphology and structural properties of the Cu{sub 3}BiS{sub 3} thin films were studied using UV-VIS-NIR spectra, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The as- synthesized Cu{sub 3}BiS{sub 3} film exhibits a direct band gap 1.56 to 1.58 eV having absorption coefficient of the order of 10{sup 5} cm{sup −1}. The XRD declares the amorphous nature of the films. SEM images shows films were composed of close-packed fine spherical nanoparticles of 70-80 nm in diameter. The chemical composition of the film was almost stoichiometric. The optical study indicates that the Cu{sub 3}BiS{sub 3} films can be applied as an absorber layer for thin film solar cells.

  3. Solvothermal modification of BiOCl nanosheets with Bi nanoparticles using ascorbic acid as reductant and the superoxide radicals dominated photocatalytic performance

    Science.gov (United States)

    Cui, Zhankui; Gao, Keke; Ge, Suxiang; Fa, Wenjun

    2017-11-01

    BiOCl nanosheets were solvothermally modified with Bi nanoparticles (NPs) using ascorbic acid as the reductant. The structures of Bi/BiOCl composites were characterized by XRD, Raman spectroscopy, FTIR spectroscopy and SEM. The light absorption properties were measured by UV-vis-NIR spectroscopy. The photocatalytic performances were evaluated by photodegrading methyl orange (MO) and the photocatalytic mechanism was investigated using trapping experiments and a fluorescent probe method. The results show that Bi NPs are uniformly distributed on the surfaces of BiOCl nanosheets and the modification amount of Bi NPs could be well controlled because of the mild property of ascorbic acid as reducing agent. The photocatalytic activities for the composites are improved obviously and the best photocatalytic performance is obtained when the weight ratio of Bi and BiOCl is1:10 and the photochemical reaction rate is 3.5 times that of pure BiOCl nanosheets and 19.7 times of Bi powders. The enhanced photocatalytic efficiency is ascribed to the favorable formation of dominant \\cdot O2- radicals caused by the increased photoinduced electrons from both Bi NPs and BiOCl nanosheets.

  4. Effect of oxidant on resputtering of Bi from Bi--Sr--Ca--Cu--O films

    International Nuclear Information System (INIS)

    Grace, J.M.; McDonald, D.B.; Reiten, M.T.; Olson, J.; Kampwirth, R.T.; Gray, K.E.

    1992-01-01

    The type and partial pressure of oxidant mixed with argon can affect the selective sputtering of Bi in composite-target, magnetron-sputtered Bi--Sr--Ca--Cu--O films. Comparative studies using oxygen and ozone show that ozone is a more potent oxidant, as well as a more potent source of resputterers than is oxygen. Severe resputtering from ozone is significantly reduced by a -40 V potential on the sample block. We suggest that oxygen causes resputtering by forming O + 2 , which interacts with the target to produce energetic O - . In contrast, ozone may form lower-energy O - by electron impact in the dark space. Negative oxygen ions from the target itself may be responsible for a background resputtering effect. Our results and those found for Y--Ba--Cu--O by others are comparable. Bi in Bi--Sr--Ca--Cu--O behaves as Ba in Y--Ba--Cu--O, with regard to selective resputtering; furthermore, the response of Sr, Ca, and Cu to oxygen in sputtered Bi--Sr--Ca--Cu--O is similar to what is observed for Cu in Y--Ba--Cu--O

  5. Microstructure of thermoelectric (Bi0.15Sb0.85)2Te3 film

    International Nuclear Information System (INIS)

    Yildiz, Koksal; Akgul, Unal; Atici, Yusuf; Leipner, Hartmut S.

    2014-01-01

    The film of thermoelectric ternary p-type (Bi 0.15 Sb 0.85 ) 2 Te 3 was deposited on polyimide foil substrate at 168 C using direct-current magnetron sputtering. Microstructural investigations of the film were performed by electron microscopy techniques. SEM observations showed that the film surface consisted of large-sized particulates with small-sized particles and also mound-like crystal agglomerates in some areas. Chemical composition of the film was analyzed using energy-dispersive X-ray spectrometer (EDS). It has been observed that the EDS results were in an agreement with nominal composition for the film. Detailed microstructural investigations were carried out using transmission electron microscopy (TEM). TEM images and selected area electron diffraction patterns showed that the film has randomly oriented polycrystalline grain structure. High-resolution TEM images indicated that the microstructure of film also contained nano-crystal structure, smaller than 10 nm. (orig.)

  6. A study of the formation processes of the 2212 phase in the Bi-based superconductor systems. [BiSrCaCuO

    Energy Technology Data Exchange (ETDEWEB)

    Wai, Lo; Glowacki, B A [Interdisciplinary Research Centre in Superconductivity, Univ. of Cambridge (United Kingdom)

    1992-04-15

    A study towards the identification of the reactions contributing to and accompanying the formation of the 2212 phase from oxides and carbonates by solid state reaction processes was conducted. The formation processes were investigated by thermal analysis, powder X-ray diffractometry and AC magnetic susceptometry. The 2212 phase was found to form from reactions between the 2201 phases (the non-superconducting pseudo-tetragonal and the superconducting monoclinic phases), Bi{sub 6}Ca{sub 7}O{sub 16}, CuO and SrCO{sub 3}. The 2201 phases were produced by the reactions of Bi-Sr-Cu-O or Bi-Sr-O compounds with SrCO{sub 3} or CuO. The 2201 phases could also be formed through the direct reaction between Bi{sub 2}CuO{sub 4} and SrCO{sub 3}. (orig.).

  7. Antiphase Boundaries in the Turbostratically Disordered Misfit Compound (BiSe)(1+δ)NbSe2.

    Science.gov (United States)

    Mitchson, Gavin; Falmbigl, Matthias; Ditto, Jeffrey; Johnson, David C

    2015-11-02

    (BiSe)(1+δ)NbSe2 ferecrystals were synthesized in order to determine whether structural modulation in BiSe layers, characterized by periodic antiphase boundaries and Bi-Bi bonding, occurs. Specular X-ray diffraction revealed the formation of the desired compound with a c-axis lattice parameter of 1.21 nm from precursors with a range of initial compositions and initial periodicities. In-plane X-ray diffraction scans could be indexed as hk0 reflections of the constituents, with a rectangular basal BiSe lattice and a trigonal basal NbSe2 lattice. Electron micrographs showed extensive turbostratic disorder in the samples and the presence of periodic antiphase boundaries (approximately 1.5 nm periodicity) in BiSe layers oriented with the [110] direction parallel to the zone axis of the microscope. This indicates that the structural modulation in the BiSe layers is not due to coherency strain resulting from commensurate in-plane lattices. Electrical transport measurements indicate that holes are the dominant charge carrying species, that there is a weak decrease in resistivity as temperature decreases, and that minimal charge transfer occurs from the BiSe to NbSe2 layers. This is consistent with the lack of charge transfer from the BiX to the TX2 layers reported in misfit layer compounds where antiphase boundaries were observed. This suggests that electronic considerations, i.e., localization of electrons in the Bi-Bi pairs at the antiphase boundaries, play a dominant role in stabilizing the structural modulation.

  8. Hydrothermal Synthesis, Characterization, and Optical Properties of Ce Doped Bi2MoO6 Nanoplates

    Directory of Open Access Journals (Sweden)

    Anukorn Phuruangrat

    2014-01-01

    Full Text Available Undoped and Ce doped Bi2MoO6 samples were synthesized by hydrothermal reaction at 180°C for 20 h. Phase, morphology, atomic vibration, and optical properties were characterized by X-ray powder diffraction (XRD, X-ray photoelectron spectroscopy (XPS, Raman spectrophotometry, Fourier transform infrared (FTIR spectroscopy, scanning electron microscopy (SEM, transmission electron microscopy (TEM, selected area electron diffraction (SAED, and UV-visible spectroscopy. In this research, the products were orthorhombic Bi2MoO6 nanoplates with the growth direction along the [0b0], including the asymmetric and symmetric stretching and bending modes of Bi–O and Mo–O. Undoped and Ce doped Bi2MoO6 samples show a strong absorption in the UV region.

  9. Scavenger Receptor BI Plays a Role in Facilitating Chylomicron Metabolism

    NARCIS (Netherlands)

    Out, R.; Kruijt, J.K.; Rensen, P.C.N.; Hildebrand, R.B.; Vos, P. de; Eck, M. van; Berkel, T.J.C. van

    2004-01-01

    The function of scavenger receptor class B type I (SR-BI) in mediating the selective uptake of high density lipoprotein (HDL) cholesterol esters is well established. However, the potential role of SR-BI in chylomicron and chylomicron remnant metabolism is largely unknown. In the present

  10. X-ray standing wave study of the Bi/GaAs and Bi/GaP interfaces

    International Nuclear Information System (INIS)

    Herrera-Gomez, A.

    1994-04-01

    Interfaces are one of the most important elements determining the characteristics of electronic devices. Composite semiconductors, specifically the III-V family, are technologically attractive because of their mobility and optical properties, and also because they offer the possibility of engineering such properties as the size of the band gap. Nevertheless, Si has remained the most utilized semiconductor material, primarily because the fabrication of practical MOSFETs with III-V semiconductors remains elusive. Examples of such complex interfaces are the structures formed by one monolayer of Bi on the (110) surface of GaAs and GaP. While better matched Column V elements form epitaxial continuous monolayers on III-V semiconductor (110) surfaces, Bi is too large to accommodate on GaAs and GaP surfaces with long range order, and vacancies appear to allow relaxation. For the ideal systems, symmetry imposes the presence of only two nonequivalent adatom sites. However, for Bi/GaAs and Bi/GaP, more than two different sites are present because the position of Bi atoms next to a vacancy is not necessarily equivalent to that between other Bi atoms. The geometry of the Bi/GaAs and Bi/GaP systems was determined here by triangulating XSW results from three Bragg planes. A methodology was developed that provides an intrinsic check of the validity of assuming two sites for the overlayer structures. An experimental method was developed that allows the three reflections to be measured on the same sample, thus reducing the number of experimental variables, such as the degree of disorder. The traditional method of analysis was not accurate enough for this data, so a more reliable and faster method of data fitting was developed. A configuration used in the present work, which previously has been widely used, presents an intrinsic multireflection problem. This issue is discussed in depth, and the appropriate method is determined for analyzing the data obtained with this configuration

  11. Magnetoresistance and magnetothermopower properties of Bi/Ca/Co/O and Bi(Pb)/Ca/Co/O misfit layer cobaltites

    CERN Document Server

    Maignan, A; Hervieu, M; Michel, C; Pelloquin, D; Khomskii, D

    2003-01-01

    Two new compounds of the Bi/Ca/Co/O and Bi(Pb)/Ca/Co/O systems have been prepared. Their structure is built up from the intergrowth of four rock-salt-type layers and one [CoO sub 2 ] hexagonal layer. Both cobaltites exhibit large thermopower values (S sub 3 sub 0 sub 0 sub K approx 140 mu V K sup - sup 1), low resistivity values (rho sub 3 sub 0 sub 0 sub K = 40-60 m OMEGA cm) and small thermal conductivities (kappa sub 3 sub 0 sub 0 sub K approx 1 W K sup - sup 1 m sup - sup 1). Furthermore, these compounds exhibit a negative magnetoresistance, (MR = rho sub H - rho sub H sub sub 0 /rho sub H sub = sub 0), reaching, at 2.5 K, - 85% in 7 T for the Bi/Ca/Co/O misfit cobaltite. A large negative magnetothermopower is also found for these cobaltites in the same temperature range. A qualitative explanation of the observed behaviour is proposed.

  12. Mechanism and bias considerations for design of a bi-directional pneumatic artificial muscle actuator

    International Nuclear Information System (INIS)

    Vocke III, Robert D; Wereley, Norman M; Kothera, Curt S

    2014-01-01

    Pneumatic artificial muscles (PAMs), or McKibben actuators, have received considerable attention for robotic manipulators and in aerospace applications due to their similarity to natural muscles. Like natural muscles, PAMs are a purely contractile actuator, so that, in order to produce bi-directional or rotational motion, they must be arranged in an agonist/antagonist pair, which inherently limits the deflection of the system due to the high parasitic stiffness of the antagonistic PAM. This study presents two methods for increasing the performance of an antagonistic PAM system by decreasing the passive parasitic torque, rather than increasing the active torque. The first involves selection of the kinematic mechanism geometry, and the second involves the introduction of bias into the system, both in terms of PAM contraction and passive (antagonistic) PAM pressure. It was found with the proper selection of design parameters, including mechanism geometry, PAM geometry, and bias conditions, that an ideal actuator configuration can be chosen that maximizes deflection for a given arbitrary loading. When comparing a baseline design to an improved design for a simplified case, a nearly 50% increase in maximum deflection was predicted simply by optimizing mechanism geometry and bias contraction. These results were experimentally verified with quasi-static testing that showed a 300% increase in actuator deflection over the baseline design. (paper)

  13. Bi-directional Reflectance of Icy Surface Analogs: A Dual Approach

    Science.gov (United States)

    Quinones, Juan Manuel; Vides, Christina; Nelson, Robert M.; Boryta, Mark; Mannat, Ken s.

    2018-01-01

    Bi-directional reflectance measurements of analogs for planetary regolith have provided insight into the surface properties of planetary satellites and small bodies. Because Aluminum Oxide (Al2O3) and water ice share a similar hexagonal crystalline structure, the former has been used in laboratory experiments to simulate the regolith of both icy and dusty planetary bodies. By measuring various sizes of well sorted size fractions of Al2O3, the reflectance phase curve and porosity of a planetary regolith can be determined. We have designed an experiment to test the laboratory measurements produced by Nelson et al. (2000). Additionally, we made reflectance measurements for other alkali-halide compounds that could be used for applications beyond astronomy and planetary science.In order to provide an independent check on the Nelson et al. data, we designed an instrument with a different configuration. While both instruments take bidirectional reflectance measurements, our instrument, the Rigid Photometric Goniometer (RPG), is fixed at a phase angle of 5° and detects the scattered light with a photomultiplier tube (PMT). The PMT current is then measured with an electrometer. Following the example of Nelson et al., we measured the bidirectional reflectance of Al2O3 particulate size fractions between 0.1sizes from 20size that provided optimal, or maximum, reflectance for each compound. Our conclusions bring confirmation and clarity to photometric sciences.

  14. A novel biosensor based on the direct electrochemistry of horseradish peroxidase immobilized in the three-dimensional flower-like Bi{sub 2}WO{sub 6} microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hui, E-mail: liuhui@sust.edu.cn; Guo, Kai; Duan, Congyue; Chen, Xianjin; Zhu, Zhenfeng

    2016-07-01

    Three-dimensional flower-like Bi{sub 2}WO{sub 6} microspheres (3D-Bi{sub 2}WO{sub 6} MSs) have been synthesized through a simple hydrothermal method. The morphology and structure of 3D-Bi{sub 2}WO{sub 6} MSs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The 3D-Bi{sub 2}WO{sub 6} MSs subsequently were used to immobilize horseradish peroxidase (HRP) and fabricate a mediator-free biosensor for the detection of H{sub 2}O{sub 2}. Spectroscopic and electrochemical results reveal that 3D-Bi{sub 2}WO{sub 6} MSs constitute an excellent immobilization matrix with biocompatibility for enzymes. Meanwhile, due to unique morphology of the flower-like microspheres, the direct electron transfer of HRP is facilitated and the prepared biosensors display good performances for the detection of H{sub 2}O{sub 2} with a wide linear range, including two linear sections: 0.5–100 μM (R{sup 2} = 0.9983) and 100–250 μM (R{sup 2} = 0.9981), as well as an extremely low method detection limit of 0.18 μM. - Highlights: • 3D-Bi{sub 2}WO{sub 6} microspheres are used to fabricate a mediator-free biosensor firstly. • The biosensor displays a wide linear range of 0.5–250 μM for H{sub 2}O{sub 2}. • The biosensor exhibits a low detection limit of 0.18 μM for H{sub 2}O{sub 2}.

  15. Microwave-assisted solvothermal synthesis of flower-like Ag/AgBr/BiOBr microspheres and their high efficient photocatalytic degradation for p-nitrophenol

    International Nuclear Information System (INIS)

    Li, Tingting; Luo, Shenglian; Yang, Lixia

    2013-01-01

    Flower-like Ag/AgBr/BiOBr microspheres were successfully fabricated by the approach of microwave-assisted solvothermal and in situ photo-assisted reduction. A reactive ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C 16 mim]Br) was employed as Br source in the presence of surfactant polyvinylpyrrolidone (PVP). The photocatalytic activity of Ag/AgBr/BiOBr towards the decomposition of p-nitrophenol under visible light irradiation was evaluated. The results indicated that Ag/AgBr/BiOBr showed enhanced photocatalytic activity towards p-nitrophenol, comparing with P25, BiOBr and Ag/AgBr. More than 96% of p-nitrophenol was decomposed in 3.5 h under visible-light irradation. The excellent photocatalytic activity of flower-like Ag/AgBr/BiOBr microspheres can be attributed to the large specific surface area, strong visible-light absorption, suitable energy band structure and surface plasmon resonance effect of Ag nanoparticles. The possible photocatalytic mechanism was proposed based on the active species test and band gap structure analysis. - Graphical abstract: The photocatalytic reaction mechanisms of the as-prepared Ag/AgBr/BiOBr. Display Omitted - Highlights: • Successful synthesis of flower-like Ag/AgBr/BiOBr microspheres. • The Ag/AgBr/BiOBr showed much higher photocatalytic activity towards p-nitrophenol as compared to BiOBr and Ag/AgBr. • The reasons for the excellent photocatalytic activity are the large specific surface area, strong visible-light absorption and surface plasmon resonance effect of Ag nanoparticles. • The O 2 · − , Br 0 and photogenerated h + play key roles in the photocatalytic degradation process

  16. Bi-Directional Brillouin Optical Time Domain Analyzer System for Long Range Distributed Sensing

    Science.gov (United States)

    Guo, Nan; Wang, Liang; Wang, Jie; Jin, Chao; Tam, Hwa-Yaw; Zhang, A. Ping; Lu, Chao

    2016-01-01

    We propose and experimentally demonstrate a novel scheme of bi-directional Brillouin time domain analyzer (BD-BOTDA) to extend the sensing range. By deploying two pump-probe pairs at two different wavelengths, the Brillouin frequency shift (BFS) distribution over each half of the whole fiber can be obtained with the simultaneous detection of Brillouin signals in both channels. Compared to the conventional unidirectional BOTDA system of the same sensing range, the proposed BD-BOTDA scheme enables distributed sensing with a performance level comparable to the conventional one with half of the sensing range and a spatial resolution of 2 m, while maintaining the Brillouin signal-to-noise ratio (SNR) and the BFS uncertainty. Based on this technique, we have achieved distributed temperature sensing with a measurement range of 81.9 km fiber at a spatial resolution of 2 m and BFS uncertainty of ~0.44 MHz without introducing any complicated components or schemes. PMID:27999250

  17. Bi-Directional Brillouin Optical Time Domain Analyzer System for Long Range Distributed Sensing.

    Science.gov (United States)

    Guo, Nan; Wang, Liang; Wang, Jie; Jin, Chao; Tam, Hwa-Yaw; Zhang, A Ping; Lu, Chao

    2016-12-16

    We propose and experimentally demonstrate a novel scheme of bi-directional Brillouin time domain analyzer (BD-BOTDA) to extend the sensing range. By deploying two pump-probe pairs at two different wavelengths, the Brillouin frequency shift (BFS) distribution over each half of the whole fiber can be obtained with the simultaneous detection of Brillouin signals in both channels. Compared to the conventional unidirectional BOTDA system of the same sensing range, the proposed BD-BOTDA scheme enables distributed sensing with a performance level comparable to the conventional one with half of the sensing range and a spatial resolution of 2 m, while maintaining the Brillouin signal-to-noise ratio (SNR) and the BFS uncertainty. Based on this technique, we have achieved distributed temperature sensing with a measurement range of 81.9 km fiber at a spatial resolution of 2 m and BFS uncertainty of ~0.44 MHz without introducing any complicated components or schemes.

  18. Reliability analysis of an LCL tuned track segmented bi-directional inductive power transfer system

    DEFF Research Database (Denmark)

    Asif Iqbal, S. M.; Madawala, U. K.; Thrimawithana, D. J.

    2013-01-01

    Bi-directional Inductive Power Transfer (BDIPT) technique is suitable for renewable energy based applications such as electric vehicles (EVs), for the implementation of vehicle-to-grid (V2G) systems. Recently, more efforts have been made by researchers to improve both efficiency and reliability...... of renewable energy systems to further enhance their economical sustainability. This paper presents a comparative reliability study between a typical BDIPT system and an individually controlled segmented BDIPT system. Steady state thermal simulation results are provided for different output power levels...... for a 1.5 kW BDIPT system in a MATLAB/Simulink environment. Reliability parameters such as failure rate and mean time between failures (MTBF) are compared between the two systems. A nonlinear programming (NP) model is developed for optimizing charging schedule for a stationery EV. A case study of EV...

  19. A realistic bi-hemispheric model of the cerebellum uncovers the purpose of the abundant granule cells during motor control.

    Science.gov (United States)

    Pinzon-Morales, Ruben-Dario; Hirata, Yutaka

    2015-01-01

    The cerebellar granule cells (GCs) have been proposed to perform lossless, adaptive spatio-temporal coding of incoming sensory/motor information required by downstream cerebellar circuits to support motor learning, motor coordination, and cognition. Here we use a physio-anatomically inspired bi-hemispheric cerebellar neuronal network (biCNN) to selectively enable/disable the output of GCs and evaluate the behavioral and neural consequences during three different control scenarios. The control scenarios are a simple direct current motor (1 degree of freedom: DOF), an unstable two-wheel balancing robot (2 DOFs), and a simulation model of a quadcopter (6 DOFs). Results showed that adequate control was maintained with a relatively small number of GCs (< 200) in all the control scenarios. However, the minimum number of GCs required to successfully govern each control plant increased with their complexity (i.e., DOFs). It was also shown that increasing the number of GCs resulted in higher robustness against changes in the initialization parameters of the biCNN model (i.e., synaptic connections and synaptic weights). Therefore, we suggest that the abundant GCs in the cerebellar cortex provide the computational power during the large repertoire of motor activities and motor plants the cerebellum is involved with, and bring robustness against changes in the cerebellar microcircuit (e.g., neuronal connections).

  20. submitter Comparison of microstructure, second phases and texture formation during melt processing of Bi-2212 mono- and multifilament wires

    CERN Document Server

    Kadar, J; Rikel, MO; Di Michiel, M; Huang, Y

    2016-01-01

    Based on simultaneous in situ high energy synchrotron micro-tomography and x-ray diffraction (XRD) measurements we compare the microstructural changes and the formation of second phases and texture during the processing of Bi-2212 round wires with 15 μm filament diameter (multifilament) and 650 μm filament diameter (monofilament) fabricated using identical Bi-2212 precursor. The monofilament tomograms show in unprecedented detail how the distributed porosity agglomerates well before Bi-2212 melting decomposition to form lenticular voids that completely interrupt the filament connectivity along the wire axis. When the Bi-2212 phase completely melts connectivity in the axial wire direction is established via the changes in the void morphology from the lenticular voids to bubbles that remain when Bi-2212 crystallises out of the melt. By measuring the attenuation of the monochromatic x-ray beam, the associated Bi-2212 mass density changes have been monitored during the entire heat cycle. The XRD results reveal ...

  1. The highly enhanced visible light photocatalytic degradation of gaseous o-dichlorobenzene through fabricating like-flowers BiPO{sub 4}/BiOBr p-n heterojunction composites

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Xuejun [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Dong, Yuying, E-mail: dongy@dlnu.edu.cn [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Zhang, Xiaodong, E-mail: fatzhxd@126.com [Environment and Low-Carbon Research Center, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, 200093 (China); Cui, Yubo; Ou, Xiaoxia [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Qi, Xiaohui [College of Life Science, Dalian Nationalities University, Dalian, 116600 (China)

    2017-01-01

    Highlights: • Like-flowers BiPO{sub 4}/BiOBr was fabricated by mixing in solvent method. • o-Dichlorobenzene removal efficiency was 53.6% using BiPO{sub 4}/BiOBr. • The p–n junction improved o-dichlorobenzene degradation activity. - Abstract: In this paper, in order to enhance photo-induced electron-hole pairs separation of BiOBr, flowers-like BiPO{sub 4}/BiOBr p-n heterojunction composites was fabricated by a mixing in solvent method. The as-prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV–vis absorption spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and N{sub 2} adsorption-desorption. Meanwhile, their photocatalytic properties were investigated by the degradation of gaseous o-dichlorobenzene under visible light irradiation. Due to its strong adsorption capacity and the formation of p-n heterojunction, compared with BiPO{sub 4} and BiOBr, the BiPO{sub 4}/BiOBr composites showed higher photocatalytic activity in the degradation of gaseous o-DCB under visible light. Among them, 2% BiPO{sub 4}/BiOBr showed the maximum value of the activity, whose degradation rate was about 2.6 times as great as the pure BiOBr. Furthermore, the OH· was confirmed the main active species during the photocatalytic process by the trapping experiments. The outstanding performance indicated that the photocatalysts could be applied to air purification for chlorinated volatile organic compound.

  2. Bi-Directional Tuning of Amygdala Sensitivity in Combat Veterans Investigated with fMRI

    Science.gov (United States)

    Brashers-Krug, Tom; Jorge, Ricardo

    2015-01-01

    Objectives Combat stress can be followed by persistent emotional consequences. It is thought that these emotional consequences are caused in part by increased amygdala reactivity. It is also thought that amygdala hyper-reactivity results from decreased inhibition from portions of the anterior cingulate cortex (ACC) in which activity is negatively correlated with activity in the amygdala. However, experimental support for these proposals has been inconsistent. Methods We showed movies of combat and civilian scenes during a functional magnetic resonance imaging (fMRI) session to 50 veterans of recent combat. We collected skin conductance responses (SCRs) as measures of emotional arousal. We examined the relation of blood oxygenation-level dependent (BOLD) signal in the amygdala and ACC to symptom measures and to SCRs. Results Emotional arousal, as measured with SCR, was greater during the combat movie than during the civilian movie and did not depend on symptom severity. As expected, amygdala signal during the less-arousing movie increased with increasing symptom severity. Surprisingly, during the more-arousing movie amygdala signal decreased with increasing symptom severity. These differences led to the unexpected result that amygdala signal in highly symptomatic subjects was lower during the more-arousing movie than during the less-arousing movie. Also unexpectedly, we found no significant inverse correlation between any portions of the amygdala and ACC. Rather, signal throughout more than 80% of the ACC showed a strong positive correlation with signal throughout more than 90% of the amygdala. Conclusions Amygdala reactivity can be tuned bi-directionally, either up or down, in the same person depending on the stimulus and the degree of post-traumatic symptoms. The exclusively positive correlations in BOLD activity between the amygdala and ACC contrast with findings that have been cited as evidence for inhibitory control of the amygdala by the ACC. The

  3. Layer structured bismuth selenides Bi2Se3 and Bi3Se4 for high energy and flexible all-solid-state micro-supercapacitors

    Science.gov (United States)

    Hao, Chunxue; Wang, Lidan; Wen, Fusheng; Xiang, Jianyong; Li, Lei; Hu, Wentao; Liu, Zhongyuan

    2018-02-01

    In this work, bismuth selenides (Bi2Se3 and Bi3Se4), both of which have a layered rhombohedral crystal structure, have been found to be useful as electrode materials for supercapacitor applications. In a liquid electrolyte system (6M KOH), Bi2Se3 nanoplates exhibit much better performance as an electrode material than Bi3Se4 nanoparticles do, delivering a higher specific capacitance (272.9 F g-1) than that of Bi3Se4 (193.6 F g-1) at 5 mV s-1. This result may be attributed to the fact that Bi2Se3 nanoplates possess more active electrochemical surfaces for the reversible surface redox reactions owing to their planar quintuple stacked layers (septuple layers for Bi3Se4). To meet the demands of electronic skin, we used a novel flexible annular interdigital structure electrode to support the all-solid-state micro-supercapacitors (AMSCs). The Bi2Se3 AMSC device delivers a much better supercapacitor performance, exhibits a large stack capacitance of 89.5 F cm-3 at 20 mV s-1 (Bi3Se4: 79.1 F cm-3), a high energy density of 17.9 mWh cm-3 and a high power density of 18.9 W cm-3. The bismuth selenides also exhibit good cycle stability, with 95.5% retention after 1000 c for Bi2Se3 (Bi3Se4:90.3%). Clearly, Bi2Se3 nanoplates can be promising electrode materials for flexible annular interdigital AMSCs.

  4. In vitro studies of immunoglobulin heavy-chain binding protein (BiP, GRP78). Interactions of BiP with newly synthesized proteins and adenine nucleotides

    International Nuclear Information System (INIS)

    Kassenbrock, C.K.

    1988-01-01

    Here we examine the interaction of BiP with newly synthesized polypeptides in an in vitro protein translations-translocation system. We find that BiP forms tight complexes with nonglycosylated yeast invertase and incorrectly disulfide-bonded prolactin but not with glycosylated invertase or correctly disulfide-bonded prolactin. Moreover, BiP associates detectably only with completed chains of prolactin, not with chains undergoing synthesis. We conclude that BiP recognizes and binds with high affinity to aberrantly folded or aberrantly glycosylated polypeptides in vitro, but not to all nascent chains as they are folding. BiP also binds APT and can be purified by APT affinity chromatography. We show that submicromolar levels of ATP or ADP decrease the rate of absorption of 125 I-BiP to nitrocellulose filters coated with protein or nonionic detergents. ATP and ADP also protect portions of BiP from proteolytic degradation. In contrast, micromolar levels of AMP increase the rate of adsorption and the rate of proteolytic degradation of BiP. We also show that an ATPase activity co-purifies with BiP, but its slow turnover number suggests a regulatory, rather than a functional role. The BiP-associated ATPase shares several properties with the related cytoplasmic protein, HSC70/clathrin uncoating ATPase

  5. Synthesis and characterization of hierarchical Bi2MoO6/Polyaniline nanocomposite for all-solid-state asymmetric supercapacitor

    International Nuclear Information System (INIS)

    Wu, Fangsheng; Wang, Xiaohong; Zheng, Wanru; Gao, Haiwen; Hao, Chen; Ge, Cunwang

    2017-01-01

    Bi 2 MoO 6 /Polyaniline (PANI) hybrid nanocomposite with enhanced specific capacity and rate performance was synthesized by compositing Bi 2 MoO 6 with the PANI layer using sodium lignosulphonate (SLS) as a dopant through a simple chemical polymerization. The Bi 2 MoO 6 /PANI (BMP) nanocomposite affords a large reaction surface area, an excellent structural stability, a large number of active sites, good strain accommodation, and fast electron and ion transportation compared with pure Bi 2 MoO 6 , which all are beneficial for improving the electrochemical performance. Hence, the Bi 2 MoO 6 /PANI electrode with 0.15 g Bi 2 MoO 6 (BMP-2) shows a high specific capacitance of 826 F g −1 at a current density of 1 A g −1 and capacitance retention of 75.5% after 3000 cycles at a current density of 5 A g −1 , which is higher than pristine Bi 2 MoO 6 and other electrodes. In addition, an all-solid-state asymmetric supercapacitor (ASC) fabricated by the BMP-2 electrode and activated carbon (AC) displays a high specific capacitance of 90.0 F g −1 and a high energy density of 31.9 Wh kg −1 . Moreover, the BMP-2//AC ASC device exhibits high cycle stability, and 86.5% of its initial capacitance is retained after continuous 6000 cycles. Therefore, these results will promote a promising potential application of the Bi 2 MoO 6 /PANI nanocomposite for use as an effective electrode material in supercapacitors.

  6. Magnetic field induced strong valley polarization in the three-dimensional topological semimetal LaBi

    Science.gov (United States)

    Kumar, Nitesh; Shekhar, Chandra; Klotz, J.; Wosnitza, J.; Felser, Claudia

    2017-10-01

    LaBi is a three-dimensional rocksalt-type material with a surprisingly quasi-two-dimensional electronic structure. It exhibits excellent electronic properties such as the existence of nontrivial Dirac cones, extremely large magnetoresistance, and high charge-carrier mobility. The cigar-shaped electron valleys make the charge transport highly anisotropic when the magnetic field is varied from one crystallographic axis to another. We show that the electrons can be polarized effectively in these electron valleys under a rotating magnetic field. We achieved a polarization of 60% at 2 K despite the coexistence of three-dimensional hole pockets. The valley polarization in LaBi is compared to the sister compound LaSb where it is found to be smaller. The performance of LaBi is comparable to the highly efficient bismuth.

  7. Dispersion interactions between neighboring Bi atoms in (BiH3 )2 and Te(BiR2 )2.

    Science.gov (United States)

    Haack, Rebekka; Schulz, Stephan; Jansen, Georg

    2018-03-13

    Triggered by the observation of a short Bi⋯Bi distance and a BiTeBi bond angle of only 86.6° in the crystal structure of bis(diethylbismuthanyl)tellurane quantum chemical computations on interactions between neighboring Bi atoms in Te(BiR 2 ) 2 molecules (R = H, Me, Et) and in (BiH 3 ) 2 were undertaken. Bi⋯Bi distances atoms were found to significantly shorten upon inclusion of the d shells of the heavy metal atoms into the electron correlation treatment, and it was confirmed that interaction energies from spin component-scaled second-order Møller-Plesset theory (SCS-MP2) agree well with coupled-cluster singles and doubles theory including perturbative triples (CCSD(T)). Density functional theory-based symmetry-adapted perturbation theory (DFT-SAPT) was used to study the anisotropy of the interplay of dispersion attraction and steric repulsion between the Bi atoms. Finally, geometries and relative stabilities of syn-syn and syn-anti conformers of Te(BiR 2 ) 2 (R = H, Me, Et) and interconversion barriers between them were computed. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

  8. Thermoelectric power of Bi and Bi{sub 1{minus}x}Sb{sub x} alloy thin films and superlattices grown by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Cho, S; DiVenere, A; Wong, G K; Ketterson, J B; Meyer, J R; Hoffman, C A

    1997-07-01

    The authors have measured the thermoelectric power (TEP) of MBE-grown epitaxial Bi and Bi{sub 1{minus}x} alloy thin films and superlattices as a function of temperature in the range 20--300 K. They have observed that the TEP of a Bi thin film of 1 {micro}m thickness is in good agreement with the bulk single crystal value and that the TEPs for superlattices with 400 {angstrom} and 800 {angstrom} Bi well thicknesses are enhanced over the bulk values. For x = 0.072 and 0.088 in Bi{sub 1{minus}x}Sb{sub x} thin films showing semiconducting behavior, TEP enhancement was observed by a factor of two. However as Bi or Bi{sub 1{minus}x}Sb{sub x} well thickness decreases in superlattice geometry, the TEP decreases, which may be due to unintentional p-type doping.

  9. Dielectric and piezoelectric properties of BiFeO3 modified Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3 lead-free piezoelectric ceramics

    International Nuclear Information System (INIS)

    Zhou Changrong; Liu Xinyu; Li Weizhou

    2008-01-01

    The (0.82 - x)Bi 0.5 Na 0.5 TiO 3 -0.18Bi 0.5 K 0.5 TiO 3 -xBiFeO 3 (x = 0-0.07) lead-free piezoelectric ceramics were fabricated by a conventional solid-state reaction method and the effect of BiFeO 3 addition on microstructure and electrical properties of the ceramics was investigated. The specimens with x ≤ 0.05 maintained a rhombohedral-tetragonal phase coexistence and changed into a rhombohedral phase when x > 0.05 in crystal structure. The addition of BiFeO 3 caused a promoted grain growth. All the specimens reveal a low-frequency dielectric dispersion in the frequency range of 40-1 MHz. The piezoelectric constant d 33 and the electromechanical coupling factor k p show an obvious improvement by the addition of small amount of BiFeO 3 , which shows optimum values of d 33 = 170 pC/N and k p = 0.366 at x = 0.03. Contrary to the enhancement of piezoelectric properties, Q m decreases with increasing BiFeO 3 content. The mechanisms of intrinsic and extrinsic contributions to the dielectric and piezoelectric responses have been proposed. Intrinsic contributions are from the relative ion/cation shift that preserves the ferroelectric crystal structure. The remaining extrinsic contributions are from the domain-wall motion and point defects

  10. Enhanced photosensitization process induced by the p–n junction of Bi2O2CO3/BiOCl heterojunctions on the degradation of rhodamine B

    International Nuclear Information System (INIS)

    Lu, Haijing; Xu, Lingling; Wei, Bo; Zhang, Mingyi; Gao, Hong; Sun, Wenjun

    2014-01-01

    Herein, we report the enhanced photosensitization process in the nanosheet Bi 2 O 2 CO 3 /BiOCl heterojunctions photocatalyst. The combined XRD, FT-IR and Raman results have confirmed the co-existence of Bi 2 O 2 CO 3 and BiOCl phases in the composites. Although both Bi 2 O 2 CO 3 and BiOCl are wide bandgap semiconductors, the composites showed an unexpectedly high catalytic activity in decomposing RhB (rhodamine B) aqueous solution under visible light irradiation. The mechanism of enhanced photocatalytic activity was ascribed to the inner electric field formed in the Bi 2 O 2 CO 3 /BiOCl p–n junction.

  11. Large pore bi-functionalised mesoporous silica for metal ion pollution treatment

    International Nuclear Information System (INIS)

    Burke, Aoife M.; Hanrahan, John P.; Healy, David A.; Sodeau, John R.; Holmes, Justin D.; Morris, Michael A.

    2009-01-01

    Here we demonstrate aminopropyl and mercatopropyl functionalised and bi-functionalised large pore mesoporous silica spheres to extract various metal ions from aqueous solutions towards providing active sorbents for mitigation of metal ion pollution. Elemental analysis (EA) and FTIR techniques were used to quantify the attachment of the aminopropyl and mercatopropyl functional groups to the mesoporous silica pore wall. Functionalisation was achieved by post-synthesis reflux procedures. For all functionalised silicas the functionalisation refluxing does not alter particle morphology/agglomeration of the particles. It was found that sorptive capacities of the mesoporous silica towards the functional groups were unaffected by co-functionalisation. Powder X-ray diffraction (PXRD) and nitrogen adsorption techniques were used to establish the pore diameters, packing of the pores and specific surface areas of the modified mesoporous silica spheres. Atomic absorption (AA) spectroscopy and inductively coupled plasma-atomic emission spectrometry (ICP-AES) techniques were used to measure the extraction efficiencies of each metal ion species from solution at varying pHs. Maximum sorptive capacities (as metal ions) were determined to be 384 μmol g -1 for Cr, 340 μmol g -1 for Ni, 358 μmol g -1 for Fe, 364 μmol g -1 for Mn and 188 μmol g -1 for Pd

  12. Large pore bi-functionalised mesoporous silica for metal ion pollution treatment

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Aoife M.; Hanrahan, John P. [Department of Chemistry, Materials Section and Supercritical Fluid Centre, University College Cork, Cork (Ireland); Environmental Research Institute (ERI), Lee Road, Cork (Ireland); Healy, David A.; Sodeau, John R. [Department of Chemistry, Centre of Research in Atmospheric Chemistry, University College Cork, Cork (Ireland); Holmes, Justin D. [Department of Chemistry, Materials Section and Supercritical Fluid Centre, University College Cork, Cork (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland); Morris, Michael A. [Department of Chemistry, Materials Section and Supercritical Fluid Centre, University College Cork, Cork (Ireland); Environmental Research Institute (ERI), Lee Road, Cork (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin 2 (Ireland)], E-mail: m.morris@ucc.ie

    2009-05-15

    Here we demonstrate aminopropyl and mercatopropyl functionalised and bi-functionalised large pore mesoporous silica spheres to extract various metal ions from aqueous solutions towards providing active sorbents for mitigation of metal ion pollution. Elemental analysis (EA) and FTIR techniques were used to quantify the attachment of the aminopropyl and mercatopropyl functional groups to the mesoporous silica pore wall. Functionalisation was achieved by post-synthesis reflux procedures. For all functionalised silicas the functionalisation refluxing does not alter particle morphology/agglomeration of the particles. It was found that sorptive capacities of the mesoporous silica towards the functional groups were unaffected by co-functionalisation. Powder X-ray diffraction (PXRD) and nitrogen adsorption techniques were used to establish the pore diameters, packing of the pores and specific surface areas of the modified mesoporous silica spheres. Atomic absorption (AA) spectroscopy and inductively coupled plasma-atomic emission spectrometry (ICP-AES) techniques were used to measure the extraction efficiencies of each metal ion species from solution at varying pHs. Maximum sorptive capacities (as metal ions) were determined to be 384 {mu}mol g{sup -1} for Cr, 340 {mu}mol g{sup -1} for Ni, 358 {mu}mol g{sup -1} for Fe, 364 {mu}mol g{sup -1} for Mn and 188 {mu}mol g{sup -1} for Pd.

  13. Photocatalytic perfermance of sandwich-like BiVO{sub 4} sheets by microwave assisted synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Suqin, E-mail: liusuqin888@126.com [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices, Xiangyang 441053 (China); Tang, Huiling; Zhou, Huan [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Dai, Gaopeng, E-mail: dgp2000@126.com [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China); Wang, Wanqiang [Department of Chemical engineering and Food Science, Hubei University of arts and science, Xiangyang 441053 (China)

    2017-01-01

    Graphical abstract: Sandwich-like BiVO{sub 4} sheets were successfully synthesized via a facile microwave-assisted method. The as-prepared samples exhibit a high activity for the degradation of methyl orange under visible light irradiation. - Highlights: • Sandwich-like BiVO{sub 4} sheets were synthesized by a facile microwave-assisted method. • The presence of PEG-10000 plays a critical role in the formation of BiVO{sub 4} sheets. • Ostwald ripening is the primary driving force for the formation of sandwich-like BiVO{sub 4}. • The sandwich-like BiVO{sub 4} sheets exhibit a high visible-light photocatalytic activity. - Abstract: Sandwich-like BiVO{sub 4} sheets were successfully synthesized in an aqueous solution containing bismuth nitrate, ammonium metavanadate and polyethylene glycol with a molecular weight of 10,000 (PEG-10000) using a facile microwave-assisted method. The as-prepared samples were characterized by scanning electron microscopy, N{sub 2} adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy. The results show that the presence of PEG-10000 plays a critical role in the formation of BiVO{sub 4} sheets, and Ostwald ripening is the primary driving force for the formation of sandwich-like structures. The sandwich-like BiVO{sub 4} sheets exhibit a high activity for the degradation of methyl orange under visible light irradiation (λ ≥ 420 nm). The enhancement of photocatalytic activity of sandwich-like BiVO{sub 4} sheets can be attributed to its large surface area over the irregular BiVO{sub 4} particles.

  14. Anharmonic phonons and magnons in BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Delaire, Olivier A [ORNL; Ma, Jie [ORNL; Stone, Matthew B [ORNL; Huq, Ashfia [ORNL; Gout, Delphine J [ORNL; Brown, Craig [National Institute of Standards and Technology (NIST); Wang, Kefeng [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing; Ren, Zhifeng [Boston College, Chestnut Hill

    2012-01-01

    The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO3 were measured for temperatures 200 < T < 750K , using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO3 closely resembles that of similar Fe perovskites, such as LaFeO3, despite the cycloid modulation in BiFeO3. We do not find any evidence for a spin gap. A strong T-dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large amplitude motions of Bi and O ions observed with neutron diffraction. These results highlight the importance of spin-phonon coupling in this material.

  15. Bismuth oxychloride homogeneous phasejunction BiOCl/Bi12O17Cl2 with unselectively efficient photocatalytic activity and mechanism insight

    Science.gov (United States)

    Hao, Lin; Huang, Hongwei; Guo, Yuxi; Du, Xin; Zhang, Yihe

    2017-10-01

    Fabrication of homo/hetero-junctions by coupling of wide-band gap semiconductor and narrow-band gap semiconductor is desirable as they can achieve a decent balance between photoabsorption and photo-redox ability. Herein, a n-n type bismuth oxychloride homogeneous phasejunction BiOCl/Bi12O17Cl2 was developed by facilely manipulating the basicity in a one-pot hydrothermal process. Compared with BiOCl which only responds to UV light, the photo-responsive range is remarkably extended to visible region. The BiOCl/Bi12O17Cl2 phasejunctions show much higher photocatalytic activity than the single BiOCl and Bi12O17Cl2 toward degradation of methyl orange (MO) under simulated solar light. In particular, it presented a high photo-oxidation ability in degrading diverse industrial contaminants including 2,4-dichlorophenol (2,4-DCP), phenol, bisphenol A (BPA) and tetracycline hydrochloride. Based on a series of photoelectrochemical and photoluminescence measurements, the fortified photocatalytic performance of BiOCl/Bi12O17Cl2 phasejunctions was manifested to be attributed to the efficient separation and transfer efficiencies of photoinduced electron-hole pairs because of the junctional interface formed between BiOCl and Bi12O17Cl2. The study may not only furnish a high-effective photocatalyst in the application of environment purification, but also pave a path to fabricate agnate phase-junctional photocatalyst.

  16. Ultrathin Topological Insulator Bi 2 Se 3 Nanoribbons Exfoliated by Atomic Force Microscopy

    KAUST Repository

    Hong, Seung Sae; Kundhikanjana, Worasom; Cha, Judy J.; Lai, Keji; Kong, Desheng; Meister, Stefan; Kelly, Michael A.; Shen, Zhi-Xun; Cui, Yi

    2010-01-01

    Ultrathin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak van der Waals interaction between adjacent quintuple layers (QLs), the layered bismuth selenide (Bi2Se 3), a single Dirac-cone topological insulator with a large bulk gap, can be exfoliated down to a few QLs. In this paper, we report the first controlled mechanical exfoliation of Bi2Se3 nanoribbons (>50 QLs) by an atomic force microscope (AFM) tip down to a single QL. Microwave impedance microscopy is employed to map out the local conductivity of such ultrathin nanoribbons, showing drastic difference in sheet resistance between 1-2 QLs and 4-5 QLs. Transport measurement carried out on an exfoliated (>5 QLs) Bi2Se3 device shows nonmetallic temperature dependence of resistance, in sharp contrast to the metallic behavior seen in thick (>50 QLs) ribbons. These AFM-exfoliated thin nanoribbons afford interesting candidates for studying the transition from quantum spin Hall surface to edge states. © 2010 American Chemical Society.

  17. Ultrathin Topological Insulator Bi 2 Se 3 Nanoribbons Exfoliated by Atomic Force Microscopy

    KAUST Repository

    Hong, Seung Sae

    2010-08-11

    Ultrathin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak van der Waals interaction between adjacent quintuple layers (QLs), the layered bismuth selenide (Bi2Se 3), a single Dirac-cone topological insulator with a large bulk gap, can be exfoliated down to a few QLs. In this paper, we report the first controlled mechanical exfoliation of Bi2Se3 nanoribbons (>50 QLs) by an atomic force microscope (AFM) tip down to a single QL. Microwave impedance microscopy is employed to map out the local conductivity of such ultrathin nanoribbons, showing drastic difference in sheet resistance between 1-2 QLs and 4-5 QLs. Transport measurement carried out on an exfoliated (>5 QLs) Bi2Se3 device shows nonmetallic temperature dependence of resistance, in sharp contrast to the metallic behavior seen in thick (>50 QLs) ribbons. These AFM-exfoliated thin nanoribbons afford interesting candidates for studying the transition from quantum spin Hall surface to edge states. © 2010 American Chemical Society.

  18. Highly efficient visible-light-induced photocatalytic activity of Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterojunction photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Chaiwichian, Saranyoo [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai50200 (Thailand); Inceesungvorn, Burapat [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wetchakun, Khatcharin [Program of Physics, Faculty of Science, Ubon Ratchathani Rajabhat University, Ubon Ratchathani 34000 (Thailand); Phanichphant, Sukon [Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Kangwansupamonkon, Wiyong [National Nanotechnology Center, Thailand Science Park, Phahonyotin Road, Klong 1, Klong Luang, Phathumthani 12120 (Thailand); Wetchakun, Natda, E-mail: natda_we@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai50200 (Thailand)

    2014-06-01

    Highlights: • Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterojunction photocatalysts were obtained using hydrothermal method. • Physicochemical properties played a significant role on photocatalytic efficiency. • Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterogeneous structures were greatly enhanced for degradation of MB. • A tentative mechanism of charge transfer process in MB degradation was proposed. - Abstract: The Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterojunction photocatalysts were synthesized by hydrothermal method. Physical properties of the heterojunction photocatalyst samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The XRD results indicated that BiVO{sub 4} retain monoclinic and tetragonal structures, while Bi{sub 2}WO{sub 6} presented as orthorhombic structure. The Brunauer, Emmett and Teller (BET) adsorption–desorption of nitrogen gas for specific surface area determination at the temperature of liquid nitrogen was performed on all samples. UV–vis diffuse reflectance spectra (UV–vis DRS) were used to identify the absorption range and band gap energy of the heterojunction photocatalysts. The photocatalytic performance of Bi{sub 2}WO{sub 6}/BiVO{sub 4} heterojunction photocatalysts was studied via the photodegradation of methylene blue (MB) under visible light irradiation. The results indicated that the heterojunction photocatalyst at 0.5:0.5 mole ratio of Bi{sub 2}WO{sub 6}:BiVO{sub 4} shows the highest photocatalytic activity.

  19. Bi-cooperative games in bipolar fuzzy settings

    Science.gov (United States)

    Hazarika, Pankaj; Borkotokey, Surajit; Mesiar, Radko

    2018-01-01

    In this paper, we introduce the notion of a bi-cooperative game with Bipolar Fuzzy Bi-coalitions and discuss the related properties. In many decision-making situations, players show bipolar motives while cooperating among themselves. This is modelled in both crisp and fuzzy environments. Bi-cooperative games with fuzzy bi-coalitions have already been proposed under the product order of bi-coalitions where one had memberships in [0, 1]. In the present paper, we adopt the alternative ordering: ordering by monotonicity and account for players' memberships in ?, a break from the previous formulation. This simplifies the model to a great extent. The corresponding Shapley axioms are proposed. An explicit form of the Shapley value to a particular class of such games is also obtained. Our study is supplemented with an illustrative example.

  20. Potential barrier behavior in BiCuVOX materials Comportamento da barreira de potencial em materiais BiCuVOX

    Directory of Open Access Journals (Sweden)

    S. M. Gheno

    2011-12-01

    Full Text Available The BiMeVOX materials appear being high attractive for applications at low temperatures when the ionic conductivity is the determining parameter. The occurrence of many types substitution was confirmed for numerous Me ions, but the greatest interest have been focused on the BiCuVOX materials. The objective of this study was to image the potential barriers in BiCuVOX. The sample was sintered for 4 h at 750 °C and the results show that the high density compound can be obtained. Simultaneously, topography and electric force microscopy (EFM images are viewed side-by-side. EFM experiments were performed and the results show the maps of the electric field distribution on the surface of BiCuVOX. The formation of potential barrier was observed and the width and intensity were measured.Materiais do tipo BiMeVOX são muito atrativos para aplicações em baixas temperaturas quando a condutividade iônica for o parâmetro determinante. A ocorrência de muitos tipos de substituições foi confirmada para numerosos íons Me, dentre os quais, existe um grande interesse no estudo de materiais BiCuVOX. O objetivo deste estudo foi realizar o imageamento das barreiras de potencial em uma amostra de material BiCuVOX. A amostra foi sinterizada 4 h a 750 °C e apresentou alta densidade. Imagens da superfície topográfica e de microscopia de força elétrica (EFM foram obtidas simultaneamente em um microscópio de varredura por sonda. Os experimentos EFM mostraram um mapa da distribuição do campo elétrico na superfície do material BiCuVOx. A formação da barreira de potencial foi observada e tanto a largura quanto a altura foram medidas.

  1. Unusual Concentration Induced Antithermal Quenching of the Bi(2+) Emission from Sr2P2O7:Bi(2.).

    Science.gov (United States)

    Li, Liyi; Peng, Mingying; Viana, Bruno; Wang, Jing; Lei, Bingfu; Liu, Yingliang; Zhang, Qinyuan; Qiu, Jianrong

    2015-06-15

    The resistance of a luminescent material to thermal quenching is essential for the application in high power LEDs. Usually, thermal luminescence quenching becomes more and more serious as the activator concentration increases. Conversely, we found here that a red phosphor Sr2P2O7:Bi(2+) is one of the exceptions to this as we studied the luminescence properties at low (10-300 K) and high (300-500 K) temperatures. As Bi(2+) ions are incorporated into Sr2P2O7, they exhibit the emissions at ∼660 and ∼698 nm at room temperature and are encoded, hereafter, as Bi(1) and Bi(2) due to the substitutions for two different crystallographic sites Sr(1) and Sr(2), respectively, in the compound. However, they will not substitute for these sites equally. At lower dopant concentration, they will occupy preferentially Sr(2) sites partially due to size match. As the concentration increases, more Bi(2+) ions start to occupy the Sr(1) sites. This can be verified by the distinct changes of emission intensity ratio of Bi(2) to Bi(1). As environment temperature increases, the thermal quenching happens, but it can be suppressed by the Bi(2+) concentration increase. This becomes even more pronounced in Bi(2+) heavily doped sample as we decompose the broad emission band into separated Bi(1) and Bi(2) Gaussian peaks. For the sample, the Bi(1) emission at ∼660 nm even shows antithermal-quenching particularly at higher temperatures. This phenomenon is accompanied by the blue shift of the overall emission band and almost no changes of lifetimes. A mechanism is proposed due to volume expansion of the unit cell, the increase of Bi(1) content, and temperature dependent energy transfer between Bi(2) and Bi(1). This work helps us better understand the complex luminescent behavior of Bi(2+) doped materials, and it will be helpful to design in the future the heavily doped phosphor for WLEDs with even better resistance to thermal quenching.

  2. Layer Structured Bismuth Selenides of Bi2Se3 and Bi3Se4 for High Energy and Flexible All-Solid-State Micro-Supercapacitors.

    Science.gov (United States)

    Hao, Chunxue; Wang, Lidan; Wen, Fusheng; Xiang, Jianyong; Li, Lei; Hu, Wentao; Liu, Zhongyuan

    2017-12-20

    Bismuth selenides (Bi2Se3 and Bi3Se4), both of which have the layered rhombohedral crystal structure, and found to be useful as electrode materials for supercapacitor application in this work. Bi2Se3 nanoplates as electrode material exhibit much better performance than that of Bi3Se4 nanoparticles in liquid electrolyte system (6 M KOH), which delivers a higher specific capacitance (272.9 F/g) than that of Bi3Se4 (193.6 F/g) at 5 mV/s. This result would may be attributed to that Bi2Se3 nanoplates possess more active electrochemical surfaces for the reversible surface redox reactions owing to its planar quintuple stacked layers (septuple layers for Bi3Se4). For the demand of electronic skin, we used a novel flexible annular interdigital structure electrode applying for all-solid-state micro-supercapacitors (AMSCs). Bi2Se3 AMSCs device delivers a much more excellent supercapacitor performance, exhibits a large stack capacitance 89.5 F/cm3 (Bi3Se4: 79.1 F/cm3) at 20 mV/s, a high energy density 17.9 mWh/cm3 and high power density 18.9 W/cm3. The bismuth selenides also exhibit good cycle stability, retention 95.5% (90.3%) after 1000 c for Bi2Se3 (Bi3Se4). Obviously, Bi2Se3 nanoplates can be promising electrode materials for flexible annular interdigital all-solid-sate supercapacitor. © 2017 IOP Publishing Ltd.

  3. Single-crystalline Bi2Sr2CaCu2O8+x detectors for direct detection of microwave radiation

    International Nuclear Information System (INIS)

    Li, M.; Winkler, D.; Yurgens, A.

    2015-01-01

    We test radiation detectors made from single-crystalline Bi 2 Sr 2 CaCu 2 O 8+x flakes put on oxidized Si substrates. The 100-nm-thick flakes are lithographically patterned into 4×12 μm 2 large rectangles embedded in thin-film log-spiral antennas. The SiO 2 layer weakens the thermal link between the flakes and the bath. Two modes of radiation detection have been observed. For a bolometric type of sensors a responsivity of ∼300 V/W and a noise equivalent power of 30 nW/√(Hz) has been deduced at 70 K. Much more sensitive is the non-bolometric device showing characteristics similar to a Golay-type detector while being at least a thousand times faster. Making smaller (sub-μm) structures is expected to significantly improve the performance of these devices and makes them very competitive among other microwave and terahertz detectors

  4. Giant magnetostriction effect near onset of spin reorientation in MnBi

    Science.gov (United States)

    Choi, Y.; Ryan, P. J.; McGuire, M. A.; Sales, B. C.; Kim, J.-W.

    2018-05-01

    In materials undergoing spontaneous symmetry breaking transitions, the emergence of multiple competing order parameters is pervasive. Employing in-field x-ray diffraction, we investigate the temperature and magnetic field dependence of the crystallographic structure of MnBi, elucidating the microscopic interplay between lattices and spin. The hexagonal phase of MnBi undergoes a spin reorientation transition (TSR), whereby the easy axis direction changes from the c axis to the basal plane. Across TSR, an abrupt symmetry change is accompanied by a clear sign change in the magnetostrictive coefficient, revealing that this transition corresponds to the onset of the spin reorientation. In the vicinity of TSR, a significantly larger in-plane magnetostrictive effect is observed, presenting the emergence of an intermediate phase that is highly susceptible to an applied magnetic field. X-ray linear dichroism shows that asymmetric Bi and Mn p orbitals do not play a role in the spin reorientation. This work suggests that the spin reorientation is caused by structural modification rather than changes in the local electronic configuration, providing a strategy for manipulating the magnetic anisotropy by external strain.

  5. Novel Bi/BiOBr/AgBr composite microspheres: Ion exchange synthesis and photocatalytic performance

    Science.gov (United States)

    Lyu, Jianchang; Li, Zhenlu; Ge, Ming

    2018-06-01

    Novel Bi/BiOBr/AgBr composite microspheres were prepared by a rational in situ ion exchange reaction between Bi/BiOBr microspheres and AgNO3. The characteristic of the as-obtained ternary microspheres was tested by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL). Under visible light irradiation, Bi/BiOBr/AgBr microspheres exhibited an excellent photocatalytic efficiency for rhodamine B (RhB) degradation, which was about 1.4 and 4.9 times as high as that of Bi/BiOBr and BiOBr/AgBr, demonstrating that the highest separation efficiency of charge carriers in the heterostructured Bi/BiOBr/AgBr. The photocatalytic activity of Bi/BiOBr/AgBr microspheres just exhibited a slight decrease after three consecutive cycles. The photocatalytic mechanism investigation confirmed that the superoxide radicals (O2•-) were the dominant reactive oxygen species for RhB degradation in Bi/BiOBr/AgBr suspension.

  6. Optical properties of a new Bi{sub 38}Mo{sub 7}O{sub 78} semiconductor with fluorite-type δ-Bi{sub 2}O{sub 3} structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zuoshan; Bi, Shala; Wan, Yingpeng [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Huang, Pengjie [College of Textile and Clothing Engineering, Soochow University, Suzhou 215006 (China); Zheng, Min, E-mail: zhengmin@suda.edu.cn [College of Textile and Clothing Engineering, Soochow University, Suzhou 215006 (China)

    2017-03-31

    Highlights: • Bi{sub 38}Mo{sub 7}O{sub 78} semiconductor nanoparticles were synthesized by sol-gel method. • Bi{sub 38}Mo{sub 7}O{sub 78} keeps the structural characteristics of the patrimonial δ-Bi{sub 2}O{sub 3} structure. • Bi{sub 38}Mo{sub 7}O{sub 78} show an efficient optical absorption in visible light. • Photocatalytic property was markedly enhanced for Bi{sub 38}Mo{sub 7}O{sub 78} nanoparticles. • The mechanism of this photocatalysis system was proposed. - Abstract: Bi{sup 3+}-containing inorganic materials usually show rich optical and electronic properties due to the hybridization between 6s and 6p electronic components together with the lone pair in Bi{sup 3+} ions. In this work, a new semiconductor of bismuth molybdate Bi{sub 38}Mo{sub 7}O{sub 78} (19Bi{sub 2}O{sub 3}·7MoO{sub 3}) was synthesized by the sol-gel film coating and the following heat process. The samples developed into nanoparticles with average size of 40 nm. The phase formation was verified via the XRD Rietveld structural refinement. Orthorhombic Bi{sub 38}Mo{sub 7}O{sub 78} can be regarded to be derived from the cubic δ-phase Bi{sub 2}O{sub 3} structure. The microstructure was investigated by SEM, EDX, TEM, BET and XPS measurements. The UV-vis absorption spectra showed that the band gap of Bi{sub 38}Mo{sub 7}O{sub 78} (2.38 eV) was greatly narrowed in comparison with Bi{sub 2}O{sub 3} (2.6 eV). This enhances the efficient absorption of visible light. Meanwhile, the conduction band of is wider and shows more dispersion, which greatly benefits the mobility of the light-induced charges taking part in the photocatalytic reactions. Bi{sub 38}Mo{sub 7}O{sub 78} nanoparticles possess efficient activities on the photodegradation of methylene blue (MB) solutions under the excitation of visible-light. The photocatalysis activities and mechanisms were discussed on the crystal structure characteristics and the measurements such as photoluminescence, exciton lifetime and XPS results.

  7. Paediatric ED BiPAP continuous quality improvement programme with patient analysis: 2005-2013.

    Science.gov (United States)

    Abramo, Thomas; Williams, Abby; Mushtaq, Samaiya; Meredith, Mark; Sepaule, Rawle; Crossman, Kristen; Burney Jones, Cheryl; Godbold, Suzanne; Hu, Zhuopei; Nick, Todd

    2017-01-16

    In paediatric moderate-to-severe asthmatics, there is significant bronchospasm, airway obstruction, air trapping causing severe hyperinflation with more positive intraplural pressure preventing passive air movement. These effects cause an increased respiratory rate (RR), less airflow and shortened inspiratory breath time. In certain asthmatics, aerosols are ineffective due to their inadequate ventilation. Bilevel positive airway pressure (BiPAP) in acute paediatric asthmatics can be an effective treatment. BiPAP works by unloading fatigued inspiratory muscles, a direct bronchodilation effect, offsetting intrinsic PEEP and recruiting collapsed alveoli that reduces the patient's work of breathing and achieves their total lung capacity quicker. Unfortunately, paediatric emergency department (PED) BiPAP is underused and quality analysis is non-existent. A PED BiPAP Continuous Quality Improvement Program (CQIP) from 2005 to 2013 was evaluated using descriptive analytics for the primary outcomes of usage, safety, BiPAP settings, therapeutics and patient disposition. PED BiPAP CQIP descriptive analytics. Academic PED. 1157 patients. A PED BiPAP CQIP from 2005 to 2013 for the usage, safety, BiPAP settings, therapeutic response parameters and patient disposition was evaluated using descriptive analytics. Safety, usage, compliance, therapeutic response parameters, BiPAP settings and patient disposition. 1157 patients had excellent compliance without complications. Only 6 (0.5%) BiPAP patients were intubated. BiPAP median settings: IPAP 18 (16,20) cm H 2 O range 12-28; EPAP 8 cmH 2 O (8,8) range 6-10; inspiratory-to-expiratory time (I:E) ratio 1.75 (1.5,1.75). Pediatric Asthma Severity score and RR decreased (pimproved therapeutics times, very low intubations and decreased PICU admissions. CQIP analysis demonstrated that using a higher IPAP, low EPAP with longer I:E optimises the patient's BiPAP settings and showed a significant improvement in PAS, RR and tidal volume. Bi

  8. Causal relationship between obesity and vitamin D status: bi-directional Mendelian randomization analysis of multiple cohorts.

    Directory of Open Access Journals (Sweden)

    Karani S Vimaleswaran

    Full Text Available Obesity is associated with vitamin D deficiency, and both are areas of active public health concern. We explored the causality and direction of the relationship between body mass index (BMI and 25-hydroxyvitamin D [25(OHD] using genetic markers as instrumental variables (IVs in bi-directional Mendelian randomization (MR analysis.We used information from 21 adult cohorts (up to 42,024 participants with 12 BMI-related SNPs (combined in an allelic score to produce an instrument for BMI and four SNPs associated with 25(OHD (combined in two allelic scores, separately for genes encoding its synthesis or metabolism as an instrument for vitamin D. Regression estimates for the IVs (allele scores were generated within-study and pooled by meta-analysis to generate summary effects. Associations between vitamin D scores and BMI were confirmed in the Genetic Investigation of Anthropometric Traits (GIANT consortium (n = 123,864. Each 1 kg/m(2 higher BMI was associated with 1.15% lower 25(OHD (p = 6.52×10⁻²⁷. The BMI allele score was associated both with BMI (p = 6.30×10⁻⁶² and 25(OHD (-0.06% [95% CI -0.10 to -0.02], p = 0.004 in the cohorts that underwent meta-analysis. The two vitamin D allele scores were strongly associated with 25(OHD (p≤8.07×10⁻⁵⁷ for both scores but not with BMI (synthesis score, p = 0.88; metabolism score, p = 0.08 in the meta-analysis. A 10% higher genetically instrumented BMI was associated with 4.2% lower 25(OHD concentrations (IV ratio: -4.2 [95% CI -7.1 to -1.3], p = 0.005. No association was seen for genetically instrumented 25(OHD with BMI, a finding that was confirmed using data from the GIANT consortium (p≥0.57 for both vitamin D scores.On the basis of a bi-directional genetic approach that limits confounding, our study suggests that a higher BMI leads to lower 25(OHD, while any effects of lower 25(OHD increasing BMI are likely to be small. Population level interventions to

  9. Heterojunction BiOI/Bi2MoO6 nanocomposite with much enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Li, Wen Ting; Zheng, Yi Fan; Yin, Hao Yong; Song, Xu Chun

    2015-01-01

    BiOI/Bi 2 MoO 6 heterostructures with different amounts of BiOI were successfully prepared via a facile deposition method. The obtained BiOI/Bi 2 MoO 6 photocatalysts exhibited much higher visible light (λ > 420 nm) induced photocatalytic activity compared with single Bi 2 MoO 6 and BiOI photocatalysts. 20 % BiOI/Bi 2 MoO 6 nanocomposite exhibited the highest photocatalytic activity with almost all RhB decomposed within 70 min. However, excess BiOI covering on the surface of Bi 2 MoO 6 can inversely reduce the photocatalytic activity. The enhanced photocatalytic activities could be resulted from the function of the novel p–n heterojunction interface between Bi 2 MoO 6 and BiOI, which could separate photoinduced carriers efficiently. Possible mechanisms on the basis of the relative band positions were also discussed

  10. Multiferroic BiFeO3-BiMnO3 Nanocheckerboard From First Principles

    OpenAIRE

    Palova, L.; Chandra, P.; Rabe, K. M.

    2010-01-01

    We present a first principles study of an unusual heterostructure, an atomic-scale checkerboard of BiFeO3-BiMnO3, and compare its properties to the two bulk constituent materials, BiFeO3 and BiMnO3. The "nanocheckerboard" is found to have a multiferroic ground state with the desired properties of each constituent: polar and ferrimagnetic due to BiFeO3 and BiMnO3, respectively. The effect of B-site cation ordering on magnetic ordering in the BiFeO3-BiMnO3 system is studied. The checkerboard ge...

  11. Synthesis and melting behaviour of Bi, Sn and Sn–Bi nanostructured alloy

    Energy Technology Data Exchange (ETDEWEB)

    Frongia, F.; Pilloni, M.; Scano, A.; Ardu, A.; Cannas, C.; Musinu, A. [Università di Cagliari, Dipartimento di Scienze Chimiche e Geologiche and Cagliari Research Unit of the National Consortium of Materials Science and Technology (INSTM), Cittadella Universitaria di Monserrato, 09042 Monserrato, CA (Italy); Borzone, G.; Delsante, S. [Department of Chemistry and Industrial Chemistry, Genoa University and Genoa Research Unit of the National Consortium of Materials Science and Technology (INSTM), Via Dodecaneso 31, I-16146 Genoa (Italy); Novakovic, R. [National Research Council (CNR), Institute for Energetics and Interphases (IENI), Via De Marini 6, 16149 Genoa (Italy); Ennas, G., E-mail: ennas@unica.it [Università di Cagliari, Dipartimento di Scienze Chimiche e Geologiche and Cagliari Research Unit of the National Consortium of Materials Science and Technology (INSTM), Cittadella Universitaria di Monserrato, 09042 Monserrato, CA (Italy)

    2015-02-25

    Highlights: • Aqueous solution route is used to produce Bi, Sn and Bi–Sn nanoparticles. • HRTEM revealed core–shell and Janus type structures of Bi–Sn nanoparticles. • Melting temperature depression of Bi and Bi–Sn nanoparticles were measured by DSC. • DSC data on Bi melting temperature depression agrees with theoretical values. - Abstract: Lead-free solders based on Bi–Sn bimetallic nanoclusters with eutectic composition (Bi{sub 43}Sn{sub 57}) were synthesized at low temperature by simultaneous reduction reaction from aqueous solution containing bismuth and tin chlorides, using potassium borohydride as a reducing agent. By the same processing route, pure bismuth and tin nanoparticles have also been prepared. Microstructure, morphology and composition of the samples were characterized by X-ray powder diffraction (XRD), transmission (TEM) and scanning electron microscopy (SEM). TEM images of Bi–Sn nanoparticles show average size ranging from 30 to 100 nm. Thermal behaviour of Bi–Sn nanopowders was studied by DSC (differential scanning calorimetry) and a melting temperature (135 °C) lower than that of the corresponding microcrystalline sample (139 °C) was observed. SEM micrographs of the thermally treated sample up to 400 °C show fine spherical grains in the micrometer range with finer powder particles on the surface. XRD powder diffraction analysis indicates the formation of bismuth and tin nanophases with an average particle size of 85 and 126 nm, respectively. The oxidation behaviour of the samples was also investigated. The results obtained have been analyzed in view of theoretical models describing the melting temperature depression of nanoparticles.

  12. Comparative study of phase structure and dielectric properties for K0.5Bi0.5TiO3-BiAlO3 and LaAlO3-BiAlO3

    International Nuclear Information System (INIS)

    Hou, Yudong; Zheng, Mupeng; Si, Meiju; Cui, Lei; Zhu, Mankang; Yan, Hui

    2013-01-01

    In this work, two perovskite-type compounds, K 0.5 Bi 0.5 TiO 3 and LaAlO 3 , have been selected as host material to incorporate with BiAlO 3 using a solid-state reaction route. The phase evolution and dielectric properties for both systems have been investigated in detail. For the K 0.5 Bi 0.5 TiO 3 -BiAlO 3 system, it is interesting to find that when using Bi 2 O 3 , Al 2 O 3 , K 2 CO 3 , and TiO 2 as starting materials, the formed compounds are K 0.5 Bi 0.5 TiO 3 -K 0.5 Bi 4.5 Ti 4 O 15 and Al 2 O 3 only plays a dopant role. There are two distinct dielectric peaks appearing in the patterns of temperature dependence of dielectric constant, corresponding to the phase-transition points of perovskite-type K 0.5 Bi 0.5 TiO 3 and Aurivillius-type K 0.5 Bi 4.5 Ti 4 O 15 , independently. In comparison, using Bi 2 O 3 , Al 2 O 3 , and La 2 O 3 as starting materials, the pure perovskite phase LaAlO 3 -BiAlO 3 can be obtained. Compared to the inherent paraelectric behavior in LaAlO 3 , the diffuse phase-transition phenomena can be observed in the LaAlO 3 -BiAlO 3 binary system, which corresponds well to the Vogel-Fulcher (VF) relationship. Moreover, compared to pure LaAlO 3 , the synthesized LaAlO 3 -BiAlO 3 compound shows enhanced dielectric properties, which are promising in application as gate dielectric materials. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. The effect of oxidant on resputtering of Bi from Bi-Sr-Ca-Cu-O films

    Science.gov (United States)

    Grace, J. M.; McDonald, D. B.; Reiten, M. T.; Olson, J.; Kampwirth, R. T.; Gray, K. E.

    1991-09-01

    The type and partial pressure of oxidant mixed with argon can affect the selective resputtering of Bi in composite-target, magnetron-sputtered Bi-Sr-Ca-Cu-O films. Comparative studies using oxygen and ozone show that ozone is a more potent oxidant, as well as a more potent source of resputterers, than is oxygen. Severe resputtering from ozone is significantly reduced by a -40 V potential on the sample block. We suggest that oxygen causes resputtering by forming O2(+)p , which interacts with the target to produce energetic O(-). In contrast, ozone may form lower-energy O(-) by electron impact in the dark space. Negative oxygen ions from the target itself may be responsible for a background resputtering effect. Our results and those found for Y-Ba-Cu-O by others are comparable. Bi in Bi-Sr-Ca-Cu-O behaves as Ba in Y-Ba-Cu-O, with regard to selective resputtering; furthermore, the response of Sr, Ca, and Cu to oxygen in sputtered Bi-Sr-Ca-Cu-O is similar to what is observed for Cu in Y-Ba-Cu-O.

  14. Optical anisotropy of Bi2Sr2CaCu2O8

    Science.gov (United States)

    Kim, J. H.; Bozovic, I.; Mitzi, D. B.; Kapitulnik, A.; Harris, J. S., Jr.

    1990-04-01

    The optical anisotropy of Bi2Sr2CaCu2O8 in the 0.08-0.5-eV region is investigated by polarized reflectance measurements on single crystals. A very large anisotropy is found in this spectral region. The in-plane reflectance exhibits metallic behavior, while the c-axis reflectance exhibits insulatorlike behavior. This result is consistent with the large anisotropy found in the resistivity of Bi2Sr2CaCu2O8. Our spectroscopic data suggest that Bi2Sr2CaCu2O8 is a quasi-two-dimensional metal similar to La2-xSrxCuO4.

  15. Bi-species imposex monitoring in Galicia (NW Spain) shows contrasting achievement of the OSPAR Ecological Quality Objective for TBT.

    Science.gov (United States)

    Ruiz, J M; Carro, B; Albaina, N; Couceiro, L; Míguez, A; Quintela, M; Barreiro, R

    2017-01-30

    Imposex is decreasing worldwide after the total ban on tributyltin (TBT) from antifouling paints. In order to assess improvement in the NE Atlantic, the OSPAR Convention designed an Ecological Quality Objective (EcoQO) based on the VDSI (vas deferens sequence index, an agreed measure of imposex) in the rock snail Nucella lapillus; wherever this is not available, the mud snail Nassarius reticulatus was proposed as a proxy. We determined VDSI in Galician populations of rock (n≥34) and mud (n≥18) snails at regular intervals from pre-ban times until 2009 and 2011, respectively. While imposex in the former started decreasing in 2006 and by 2009 the EcoQO had been met in the area, VDSI in the latter was not significantly reduced until 2011 and values contradict such an achievement. This suggests that the OSPAR imposex bi-species scheme may not be of direct application in the current post-ban scenario. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Model and algorithm for bi-fuel vehicle routing problem to reduce GHG emissions.

    Science.gov (United States)

    Abdoli, Behroz; MirHassani, Seyed Ali; Hooshmand, Farnaz

    2017-09-01

    Because of the harmful effects of greenhouse gas (GHG) emitted by petroleum-based fuels, the adoption of alternative green fuels such as biodiesel and compressed natural gas (CNG) is an inevitable trend in the transportation sector. However, the transition to alternative fuel vehicle (AFV) fleets is not easy and, particularly at the beginning of the transition period, drivers may be forced to travel long distances to reach alternative fueling stations (AFSs). In this paper, the utilization of bi-fuel vehicles is proposed as an operational approach. We present a mathematical model to address vehicle routing problem (VRP) with bi-fuel vehicles and show that the utilization of bi-fuel vehicles can lead to a significant reduction in GHG emissions. Moreover, a simulated annealing algorithm is adopted to solve large instances of this problem. The performance of the proposed algorithm is evaluated on some random instances.

  17. Bi-Histogram Equalization with Brightnes Preservation Using Contras Enhancement

    OpenAIRE

    A. Anitha Rani; Gowthami Rajagopal; A. Jagadeswaran

    2014-01-01

    Contrast enhancement is an important factor in the image preprocesing step. One of the widely acepted contrast enhancement method is the histogram equalization. Although histogram equalization achieves comparatively beter performance on almost al types of image, global histogram equalization sometimes produces excesive visual deterioration. A new extension of bi- histogram equalization caled Bi-Histogram Equalization with Neighborhod Metric (BHENM). First, large histogram bins that cause w...

  18. Superstrengthening Bi2Te3 through Nanotwinning

    Science.gov (United States)

    Li, Guodong; Aydemir, Umut; Morozov, Sergey I.; Wood, Max; An, Qi; Zhai, Pengcheng; Zhang, Qingjie; Goddard, William A.; Snyder, G. Jeffrey

    2017-08-01

    Bismuth telluride (Bi2Te3 ) based thermoelectric (TE) materials have been commercialized successfully as solid-state power generators, but their low mechanical strength suggests that these materials may not be reliable for long-term use in TE devices. Here we use density functional theory to show that the ideal shear strength of Bi2Te3 can be significantly enhanced up to 215% by imposing nanoscale twins. We reveal that the origin of the low strength in single crystalline Bi2Te3 is the weak van der Waals interaction between the Te1 coupling two Te 1 - Bi - Te 2 - Bi - Te 1 five-layer quint substructures. However, we demonstrate here a surprising result that forming twin boundaries between the Te1 atoms of adjacent quints greatly strengthens the interaction between them, leading to a tripling of the ideal shear strength in nanotwinned Bi2Te3 (0.6 GPa) compared to that in the single crystalline material (0.19 GPa). This grain boundary engineering strategy opens a new pathway for designing robust Bi2Te3 TE semiconductors for high-performance TE devices.

  19. Facile synthesis of BiOF/Bi{sub 2}O{sub 3}/reduced graphene oxide photocatalyst with highly efficient and stable natural sunlight photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Limin; Dong, Shuying; Li, Qilu; Feng, Jinglan; Pi, Yunqing; Liu, Menglin [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environmental and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China); Sun, Jingyu, E-mail: sunjy-cnc@pku.edu.cn [Center for Nanochemistry (CNC), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Sun, Jianhui, E-mail: sunjh@htu.cn [School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environmental and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, Xinxiang, Henan 453007 (China)

    2015-06-05

    Highlights: • A dual Bi-based ball-shaped material BiOF/Bi{sub 2}O{sub 3} were facilely synthesized. • The composition effect of BiOF/Bi{sub 2}O{sub 3}/RGO hybrid were probed for the first time. • The photocatalytic performances were evaluated upon natural sunlight irradiation. • The composites showed a twofold augmentation in the degradation efficiency. • The hybrid photocatalyst can be easily recycled for three times. - Abstract: A facile and efficient route for the controllable synthesis of BiOF/Bi{sub 2}O{sub 3} nanostructures by hydrolysis method was reported, where the as-prepared BiOF/Bi{sub 2}O{sub 3} was subsequently incorporated with reduced graphene oxide (RGO) sheets to form BiOF/Bi{sub 2}O{sub 3}/RGO composites. The obtained BiOF/Bi{sub 2}O{sub 3} and BiOF/Bi{sub 2}O{sub 3}/RGO composites were well characterized with the aid of various techniques to probe their crystallographic, morphological, chemical and optical properties. Photocatalytic capacities of the pure BiOF/Bi{sub 2}O{sub 3} and BiOF/Bi{sub 2}O{sub 3}/RGO composites have been investigated by the degradation of Rhodamine B (RhB)-contained wastewater under natural sunlight irradiation. A twofold augmentation of degradation efficiency was in turn observed for BiOF/Bi{sub 2}O{sub 3}/RGO composites compared with that of pure BiOF/Bi{sub 2}O{sub 3} under the natural sunlight irradiation. The optimum conditions, the effects of the active species and stabilities in photocatalytic performances of the BiOF/Bi{sub 2}O{sub 3}/RGO composites have also been probed.

  20. Preparation and Faraday rotation of Bi-YIG/PMMA nanocomposite

    Science.gov (United States)

    Fu, H. P.; Hong, R. Y.; Wu, Y. J.; Di, G. Q.; Xu, B.; Zheng, Y.; Wei, D. G.

    Bismuth-substituted yttrium iron garnet (Bi-YIG) nanoparticles (NPs) were prepared by coprecipitation and subsequent heating treatment. Thermal gravity-differential thermal analysis was performed to investigate the thermal behavior of the Bi-YIG precursors and to decide the best annealing temperature. Phase formation of garnet NPs was investigated by X-ray powder diffraction. The size of Bi-YIG NPs was investigated by transmission electron microscopy, and the magnetic properties of Bi-YIG NPs were measured using a vibrating sample magnetometer. The results show that the temperature needed for the transformation of Bi-YIG from the amorphous phase to the garnet phase decreases with increasing Bi content, and Bi-YIG NPs with sizes of 28-78 nm are obtained after heating treatment at 650-1000 °C. The saturation magnetization of Bi-YIG NPs increases as the Bi content increases. Moreover, the Faraday rotation of polymethyl methacrylate (PMMA) slices doped with Bi-YIG NPs was investigated. The results indicate that the angle of Faraday rotation increases with increasing Bi content in PMMA composites, and the maximum value of the figure of merit is 1.46°, which is comparable to the value of a sputtered film. The Bi-YIG NPs-doped PMMA slices are new promising materials for magneto-optical devices.

  1. One-pot solvothermal synthesis of three-dimensional (3D) BiOI/BiOCl composites with enhanced visible-light photocatalytic activities for the degradation of bisphenol-A

    International Nuclear Information System (INIS)

    Xiao, Xin; Hao, Rong; Liang, Min; Zuo, Xiaoxi; Nan, Junmin; Li, Laisheng; Zhang, Weide

    2012-01-01

    Highlights: ► Synthesis of 3D BiOI/BiOCl microspheres by a one-pot template-free solvothermal method. ► Photocatalyst is BiOI/BiOCl composites. ► BiOI/BiOCl composites have enhanced visible-light photocatalytic ability to bisphenol-A. ► A simple and direct photodegradation pathway of bisphenol-A is proposed. - Abstract: Three-dimensional (3D) BiOI/BiOCl composite microspheres with enhanced visible-light photodegradation activity of bisphenol-A (BPA) are synthesized by a simple, one-pot, template-free, solvothermal method using BiI 3 and BiCl 3 as precursors. These 3D hierarchical microspheres with heterojunction structures are composed of 2D nanosheets and have composition-dependent absorption properties in the ultraviolet and visible light regions. The photocatalytic oxidation of BPA over BiOI/BiOCl composites followed pseudo first-order kinetics according to the Langmuir–Hinshelwood model. The highest photodegradation efficiency of BPA, i.e., nearly 100%, was observed with the BiOI/BiOCl composite (containing 90% BiOI) using a catalyst dosage of 1 g L −1 in the BPA solution (C 0 = 20 mg L −1 , pH = 7.0) under visible light irradiation for 60 min. Under these conditions, the reaction rate constant was more than 4 and 20 times greater than that of pure BiOI and the commercially available Degussa P25, respectively. The superior photocatalytic activity of this composite catalyst is attributed to the suitable band gap energies and the low recombination rate of the photogenerated electron–hole pairs due to the presence of BiOI/BiOCl heterostructures. Only one intermediate at m/z 151 was observed in the photodegradation process of BPA by liquid chromatography combined with mass spectrometry (LC–MS) analysis, and a simple and hole-predominated photodegradation pathway of BPA was subsequently proposed. Furthermore, this photocatalyst exhibited a high mineralization ratio, high stability and easy separation for recycling use, suggesting that it is a

  2. [The Support System for Diabetic Patients at Home with Bi-Directional IT Communication].

    Science.gov (United States)

    Kubota, Masakazu; Hosoda, Kiminori; Eguchi, Kyoko; Nishijima, Yuki; Nakao, Kazuwa; Kinoshita, Ayae

    2010-12-01

    The present study analyzed the effects of bi-directional IT communication on the purpose of preventing diabetes progression and to reduce a caregiver burden. Diabetic patients were informed of the nature and purpose of the study before giving their voluntary consents to participate in the study. For the period of 12 weeks, a diabetic patient and his caregiver were communicated with a nurse through the TV telephone for 30 minutes once a week. Medical staff checked the list of weight change, compliance check, exercise habit, and attached pictures of the plate with a diabetic patient through the TV telephone in real time. We encouraged a diabetic patient to eat properly based on the diet record. The 12-week TV telephone communication resulted in the body weight decrease and HbA1c. There was a consciousness change about their daily eating habit. In the present study, the 12-week TV telephone communication once a week might be useful as an auxiliary therapy for changing a bad daily habit to a good daily habit for a diabetic patient at home.

  3. Electron diffraction study of the sillenites Bi12SiO20, Bi25FeO39 and Bi25InO39: Evidence of short-range ordering of oxygen-vacancies in the trivalent sillenites

    Directory of Open Access Journals (Sweden)

    Craig A. Scurti

    2014-08-01

    Full Text Available We present an electron diffraction study of three sillenites, Bi12SiO20, Bi25FeO39, and Bi25InO39 synthesized using the solid-state method. We explore a hypothesis, inspired by optical studies in the literature, that suggests that trivalent sillenites have additional disorder not present in the tetravalent compounds. Electron diffraction patterns of Bi25FeO39 and Bi25InO39 show streaks that confirm deviations from the ideal sillenite structure. Multi-slice simulations of electron-diffraction patterns are presented for different perturbations to the sillenite structure - partial substitution of the M site by Bi3+, random and ordered oxygen-vacancies, and a frozen-phonon model. Although comparison of experimental data to simulations cannot be conclusive, we consider the streaks as evidence of short-range ordered oxygen-vacancies.

  4. Reduction in thermal conductivity of BiSbTe lump

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Kaleem [King Saud University, Sustainable Energy Technologies Center, College of Engineering, PO Box 800, Riyadh (Saudi Arabia); Wan, C. [Tsinghua University, State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Beijing (China); Al-Eshaikh, M.A.; Kadachi, A.N. [King Saud University, Research Center, College of Engineering, PO Box 800, Riyadh (Saudi Arabia)

    2017-03-15

    In this work, systematic investigations on the thermal conductivities of BiSbTe lump, microstructured pristine BiSbTe bulk and single wall carbon nanotubes (SWCNTs)/BiSbTe bulk nanocomposites were performed. BiSbTe lumps were crushed to form a coarse powder (200 μm) and effect of particle size reduction on the effective thermal conductivity of BiSbTe (200 μm) bulk were analyzed. For further reduction in the conductivity, a two pronged strategy has been employed. First, additional refinement of BiSbTe (200 μm) were performed through ball milling in an inert environment. Second, SWCNTs in 0.75, and 1.0 vol% were distributed uniformly in the fine BiSbTe ball milled powder. The results showed that the effective thermal conductivities decrease with the reduction in the particle size from lump to BiSbTe (200 μm) bulk as well as with the addition of SWCNTs accompanied by further refinement of BiSbTe particles. The significant reduction in thermal conductivities of the lump was achieved for pure BiSbTe (200 μm) bulk and 0.75 vol% of SWCNTs/BiSbTe composite. This can be ascribed to the enhanced phonon scattering by the grain boundaries between the nanostructured BiSbTe particles as well as the interfaces between BiSbTe and the low dimensional carbon nanotubes. (orig.)

  5. Direct synthesis of antimicrobial coatings based on tailored bi-elemental nanoparticles

    Directory of Open Access Journals (Sweden)

    Giulio Benetti

    2017-03-01

    Full Text Available Ultrathin coatings based on bi-elemental nanoparticles (NPs are very promising to limit the surface-related spread of bacterial pathogens, particularly in nosocomial environments. However, tailoring the synthesis, composition, adhesion to substrate, and antimicrobial spectrum of the coating is an open challenge. Herein, we report on a radically new nanostructured coating, obtained by a one-step gas-phase deposition technique, and composed of bi-elemental Janus type Ag/Ti NPs. The NPs are characterized by a cluster-in-cluster mixing phase with metallic Ag nano-crystals embedded in amorphous TiO2 and present a promising antimicrobial activity including also multidrug resistant strains. We demonstrate the flexibility of the method to tune the embedded Ag nano-crystals dimension, the total relative composition of the coating, and the substrate type, opening the possibility of tailoring the dimension, composition, antimicrobial spectrum, and other physical/chemical properties of such multi-elemental systems. This work is expected to significantly spread the range of applications of NPs coatings, not only as an effective tool in the prevention of healthcare-associated infections but also in other technologically relevant fields like sensors or nano-/micro joining.

  6. Direct synthesis of antimicrobial coatings based on tailored bi-elemental nanoparticles

    Science.gov (United States)

    Benetti, Giulio; Cavaliere, Emanuele; Canteri, Adalberto; Landini, Giulia; Rossolini, Gian Maria; Pallecchi, Lucia; Chiodi, Mirco; Van Bael, Margriet J.; Winckelmans, Naomi; Bals, Sara; Gavioli, Luca

    2017-03-01

    Ultrathin coatings based on bi-elemental nanoparticles (NPs) are very promising to limit the surface-related spread of bacterial pathogens, particularly in nosocomial environments. However, tailoring the synthesis, composition, adhesion to substrate, and antimicrobial spectrum of the coating is an open challenge. Herein, we report on a radically new nanostructured coating, obtained by a one-step gas-phase deposition technique, and composed of bi-elemental Janus type Ag/Ti NPs. The NPs are characterized by a cluster-in-cluster mixing phase with metallic Ag nano-crystals embedded in amorphous TiO2 and present a promising antimicrobial activity including also multidrug resistant strains. We demonstrate the flexibility of the method to tune the embedded Ag nano-crystals dimension, the total relative composition of the coating, and the substrate type, opening the possibility of tailoring the dimension, composition, antimicrobial spectrum, and other physical/chemical properties of such multi-elemental systems. This work is expected to significantly spread the range of applications of NPs coatings, not only as an effective tool in the prevention of healthcare-associated infections but also in other technologically relevant fields like sensors or nano-/micro joining.

  7. In-situ synthesis of nanofibers with various ratios of BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z} for effective trichloroethylene photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yifan [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of); Park, Mira [Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Kim, Hak Yong [Department of BIN Convergence Technology, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of); Ding, Bin [College of Textiles, Donghua University, Shanghai 201620 (China); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of)

    2016-10-30

    Highlights: • BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z}/PAN fibers were synthesized by in-situ method. • Photodegradation behavior of BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z}/PAN fibers was measured under solar light irradiation. • BiOCl{sub 0.3}/BiOBr{sub 0.3}/BiOI{sub 0.4}/PAN fibers exhibited the highest photocatalytic activity. • Photocatalytic mechanism was discussed in detail. - Abstract: In this work, BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z} (x + y + z = 1) composite nanofibers were prepared through electrospinning and the sol-gel methods. Photocatalytic degradation of trichloroethylene (TCE) by BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z}/PAN nanofibers was systematically investigated via gas chromatography (GC). Optimum photocatalytic activity was achieved with BiOCl{sub 0.3}/BiOBr{sub 0.3}/BiOI{sub 0.4} fibers under solar light irradiation. X-ray photoelectron spectroscopy (XPS) peaks due to C−O and C=O were observed at 286.0 and 288.3 eV, respectively, it indicated that the BiOCl{sub x}/BiOBr{sub y}/BiOI{sub z} mixture had been successfully doped on the polyacrylonitrile (PAN) fibers. Furthermore, X-ray diffraction (XRD) results also confirmed that we had synthesized the as-prepared composite nanofibers successfully. Photocatalytic activities of BiOCl{sub 0.3}/BiOBr{sub 0.3}/BiOI{sub 0.4} were up to 3 times higher than the pure BiOCl, BiOBr and BiOI samples, respectively.

  8. PtRu/C and PtRuBi/C electrocatalysts prepared by two different methodologies of borohydride reduction process for ethanol electro-oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Brandalise, Michele; Tusi, Marcelo Marques; Piasentin, Ricardo Marcelo; Correa, Olandir Vercino; Linardi, Marcelo; Spinace, Estevam Vitorio; Oliveira Neto, Almir, E-mail: brandalise@usp.br, E-mail: mmtusi@usp.br, E-mail: rmpiasen@ipen.br, E-mail: ovcorrea@ipen.br, E-mail: mlinardi@ipen.br, E-mail: espinace@ipen.br, E-mail: aolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    PtRu/C (50:50) and PtRuBi/C (50:40:10) electrocatalysts were prepared by borohydride reduction using H{sub 2}PtCl{sub 6.6}H{sub 2}O, RuCl{sub 3.x}H{sub 2}O and Bi(NO{sub 3}){sub 3.5}H{sub 2}O as metals sources and Vulcan XC72 as support. The borohydride solution was added in two different ways: drop by drop and rapid addition of all the solution. The obtained electrocatalysts were characterized by EDX, XRD and cyclic voltammetry. The electro-oxidation of ethanol was studied by cyclic voltammetry and chronoamperometry at room temperature and on a single cell of a direct ethanol fuel cell (DEFC) at 100 deg C. PtRuBi/C electrocatalysts showed superior performance for ethanol electro-oxidation than PtRu/C electrocatalysts prepared in a similar way. However, PtRuBi/C electrocatalyst prepared by rapid addition of the borohydride solution showed superior performance for ethanol electro oxidation at room temperature, while PtRuBi/C electrocatalyst prepared by addition drop by drop of borohydride solution showed superior performance on DEFC at 100 deg C. (author)

  9. PtRu/C and PtRuBi/C electrocatalysts prepared by two different methodologies of borohydride reduction process for ethanol electro-oxidation

    International Nuclear Information System (INIS)

    Brandalise, Michele; Tusi, Marcelo Marques; Piasentin, Ricardo Marcelo; Correa, Olandir Vercino; Linardi, Marcelo; Spinace, Estevam Vitorio; Oliveira Neto, Almir

    2009-01-01

    PtRu/C (50:50) and PtRuBi/C (50:40:10) electrocatalysts were prepared by borohydride reduction using H 2 PtCl 6.6 H 2 O, RuCl 3.x H 2 O and Bi(NO 3 ) 3.5 H 2 O as metals sources and Vulcan XC72 as support. The borohydride solution was added in two different ways: drop by drop and rapid addition of all the solution. The obtained electrocatalysts were characterized by EDX, XRD and cyclic voltammetry. The electro-oxidation of ethanol was studied by cyclic voltammetry and chronoamperometry at room temperature and on a single cell of a direct ethanol fuel cell (DEFC) at 100 deg C. PtRuBi/C electrocatalysts showed superior performance for ethanol electro-oxidation than PtRu/C electrocatalysts prepared in a similar way. However, PtRuBi/C electrocatalyst prepared by rapid addition of the borohydride solution showed superior performance for ethanol electro oxidation at room temperature, while PtRuBi/C electrocatalyst prepared by addition drop by drop of borohydride solution showed superior performance on DEFC at 100 deg C. (author)

  10. Fluctuations in medium-range structure of Bi-based metallic liquid alloys

    International Nuclear Information System (INIS)

    Ueno, H; Takeda, S; Kawakita, Y; Ohara, K; Kohara, S; Itou, M; Tahara, S

    2012-01-01

    Liquid structure of Bi 50 Zn 50 , which is situated at around the Bi-rich end of miscibility gap in Bi-Zn system, has been investigated by neutron and x-ray diffraction experiments and following analysis using reverse Monte Carlo (RMC) structural modelling. Among the partial correlations calculated from the structural model obtained by RMC, the Zn-Zn partial has a large temperature variation. It is found that there are medium-range fluctuations in Zn distribution which have a scale of 10 Å.

  11. The role of the isolated 6s states in BiVO{sub 4} on the electronic and atomic structures

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jie; Wang, Lin-Wang [Joint Center for Artificial Photosynthesis and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2014-10-27

    BiVO{sub 4} is one of the most promising photoanodes for water-splitting applications. Similar to many d{sup 10} materials, where the full-shell d electrons are not directly involved in the bonding, the Bi 6s electrons form isolated low-energy bands in BiVO{sub 4}. By systematically altering the energy of the Bi 6s states, we find direct evidences that the isolated s states, through the s-p coupling, affect the BiVO{sub 4} properties, including valence band maximum position, charge density, and atomic structural distortion. We find that many good properties of BiVO{sub 4} for water splitting are related to the s-p coupling due to the existence of Bi 6s states. Based on this understanding, we propose that alloying Bi with Sb can enhance these properties, and hence improve the water-splitting efficiency.

  12. Synthesis, crystal structure, and physical properties of the Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8} phases

    Energy Technology Data Exchange (ETDEWEB)

    Forbes, Scott; Yuan, Fang [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Kosuda, Kosuke; Kolodiazhnyi, Taras [Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Mozharivskyj, Yurij, E-mail: mozhar@mcmaster.ca [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada)

    2016-01-15

    The second and third known rare-earth bismuthide oxides, Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8}, have been discovered via high temperature reactions at 1300 °C. Like its Gd–Sb–O counterparts, the Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8} phases crystallize in the monoclinic C2/m space group, with the latter containing disordered Bi atoms along the b direction of the unit cell. Unlike the RE{sub 8}Sb{sub 3}O{sub 8} series, the formation of the Gd{sub 3}BiO{sub 3} phase does not necessarily precede the formation of Gd{sub 8}Bi{sub 3}O{sub 8}, which is likely due to the difficulty of accommodating bismuth in the RE–O framework due to its larger size. Physical property measurements performed on a pure Gd{sub 8}Bi{sub 3}O{sub 8} sample reveal semiconducting behavior. Although electronic structure calculations predict metallic behavior due to an unbalanced electron count, the semiconducting behavior originates from the Anderson localization of the Bi p states near the Fermi level as a result of atomic disorder. - Graphical abstract: Reaction of GdBi and Gd{sub 2}O{sub 3} at high temperatures yields Gd–Bi–O phases. - Highlights: • Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8}, the second and third rare-earth bismuthide oxides, have been discovered. • Gd{sub 3}BiO{sub 3} and Gd{sub 8}Bi{sub 3}O{sub 8} are isostructural with RE{sub 3}SbO{sub 3} and RE{sub 8}Sb{sub 3}O{sub 8}. • Gd{sub 8}Bi{sub 3}O{sub 8} displays semiconducting behavior despite an unbalanced electron count. • Anderson localization of Bi p states results in semiconducting behavior in Gd{sub 8}Bi{sub 3}O{sub 8}.

  13. BiP Negatively Affects Ricin Transport

    Directory of Open Access Journals (Sweden)

    Kirsten Sandvig

    2013-05-01

    Full Text Available The AB plant toxin ricin binds both glycoproteins and glycolipids at the cell surface via its B subunit. After binding, ricin is endocytosed and then transported retrogradely through the Golgi to the endoplasmic reticulum (ER. In the ER, the A subunit is retrotranslocated to the cytosol in a chaperone-dependent process, which is not fully explored. Recently two separate siRNA screens have demonstrated that ER chaperones have implications for ricin toxicity. ER associated degradation (ERAD involves translocation of misfolded proteins from ER to cytosol and it is conceivable that protein toxins exploit this pathway. The ER chaperone BiP is an important ER regulator and has been implicated in toxicity mediated by cholera and Shiga toxin. In this study, we have investigated the role of BiP in ricin translocation to the cytosol. We first show that overexpression of BiP inhibited ricin translocation and protected cells against the toxin. Furthermore, shRNA-mediated depletion of BiP enhanced toxin translocation resulting in increased cytotoxicity. BiP-dependent inhibition of ricin toxicity was independent of ER stress. Our findings suggest that in contrast to what was shown with the Shiga toxin, the presence of BiP does not facilitate, but rather inhibits the entry of ricin into the cytosol.

  14. A realistic bi-hemispheric model of the cerebellum uncovers the purpose of the abundant granule cells during motor control

    Directory of Open Access Journals (Sweden)

    Ruben Dario Pinzon Morales

    2015-05-01

    Full Text Available The cerebellar granule cells (GCs have been proposed to perform lossless, adaptive spatio-temporal coding of incoming sensory/motor information required by downstream cerebellar circuits to textcolor{red}{support} motor learning, motor coordination, and cognition. Here we use a physio-anatomically inspired bi-hemispheric cerebellar neuronal network (biCNN to selectively enable/disable the output of GCs and evaluate the behavioral and neural consequences during three different control scenarios. The control scenarios are a simple direct current motor (1 degree of freedom: DOF, an unstable two-wheel balancing robot (2 DOFs, and a simulation model of a quadcopter (6 DOFs. Results showed that adequate control was maintained with a relatively small number of GCs ($<$ 200 in all the control scenarios. However, the minimum number of GCs required to successfully govern each control plant increased with their complexity (i.e., DOFs. It was also shown that increasing the number of GCs resulted in higher robustness against changes in the initialization parameters of the biCNN model (i.e., synaptic connections and synaptic weights. Therefore, we suggest that the abundant GCs in the cerebellar cortex provide the computational power during the large repertoire of motor activities and motor plants the cerebellum is involved with, and bring robustness against changes in the cerebellar microcircuit (e.g., neuronal connections.

  15. Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry.

    Science.gov (United States)

    Norris, G; McConnell, G

    2010-03-01

    A novel bi-directional pump geometry that nonlinearly increases the nonlinear optical conversion efficiency of a synchronously pumped optical parametric oscillator (OPO) is reported. This bi-directional pumping method synchronizes the circulating signal pulse with two counter-propagating pump pulses within a linear OPO resonator. Through this pump scheme, an increase in nonlinear optical conversion efficiency of 22% was achieved at the signal wavelength, corresponding to a 95% overall increase in average power. Given an almost unchanged measured pulse duration of 260 fs under optimal performance conditions, this related to a signal wavelength peak power output of 18.8 kW, compared with 10 kW using the traditional single-pass geometry. In this study, a total effective peak intensity pump-field of 7.11 GW/cm(2) (corresponding to 3.55 GW/cm(2) from each pump beam) was applied to a 3 mm long periodically poled lithium niobate crystal, which had a damage threshold intensity of 4 GW/cm(2), without impairing crystal integrity. We therefore prove the application of this novel pump geometry provides opportunities for power-scaling of synchronously pumped OPO systems together with enhanced nonlinear conversion efficiency through relaxed damage threshold intensity conditions.

  16. Crystalline and magnetooptical characteristics of (Tb,Bi)3(Fe,Ga)5O12 deposited on (Y,Nd)3Al5O12

    Science.gov (United States)

    Morimoto, Ryohei; Goto, Taichi; Nakamura, Yuichi; Boey Lim, Pang; Uchida, Hironaga; Inoue, Mitsuteru

    2018-06-01

    We prepared Bi- and Ga-substituted Tb3Fe5O12 (BiGa:TIG) films on a Nd-substituted Y3Al5O12 (Nd:YAG) single crystal substrate by pulsed laser deposition, and investigated their magnetic, optical, and magnetooptical properties. A BiGa:TIG film deposited with a substrate temperature of 700 °C shows the easy axis of magnetization along the out-of-plane direction of the film and the Faraday rotation angle of 900°/cm at a wavelength of 1064 nm. The epitaxial growth of the film is confirmed by X-ray diffraction analysis.

  17. Carbon dots/BiOCl films with enhanced visible light photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Weitian; Yu, Xiang; Shen, Yinghua; Chen, Hongbin; Zhu, Yi, E-mail: tzhury@jnu.edu.cn; Zhang, Yuanming [Jinan University, Department of Chemistry (China); Meng, Hui [Jinan University, Siyuan laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics (China)

    2017-02-15

    Novel carbon dots with a diameter of 6 nm modified BiOCl (CDs/BiOCl) photocatalyst on FTO was synthesized via a facile immobilization method at room temperature. The crystalline structures, morphologies, optical properties, and photocatalytic properties were studied. The results showed that the CDs/BiOCl films exhibited higher photocatalytic activity than pure BiOCl. The 4 wt% CDs/BiOCl film showed the best photocatalytic activity, which was about eight times than that of pure BiOCl and excellent recyclability even after four recycles. Compared with other film photocatalysts, the photocatalytic activity of 4 wt% CDs/BiOCl was also higher than that of many other photocatalysts. The enhanced activity was ascribed to the enhanced light adsorption and the improvement of charge separation. Holes and superoxide radicals ·O{sub 2}{sup −} were revealed as the dominant reactive species. The photocatalytic mechanism was proposed based on the results.

  18. Extremely large nonsaturating magnetoresistance and ultrahigh mobility due to topological surface states in the metallic Bi2Te3 topological insulator

    Science.gov (United States)

    Shrestha, K.; Chou, M.; Graf, D.; Yang, H. D.; Lorenz, B.; Chu, C. W.

    2017-05-01

    Weak antilocalization (WAL) effects in Bi2Te3 single crystals have been investigated at high and low bulk charge-carrier concentrations. At low charge-carrier density the WAL curves scale with the normal component of the magnetic field, demonstrating the dominance of topological surface states in magnetoconductivity. At high charge-carrier density the WAL curves scale with neither the applied field nor its normal component, implying a mixture of bulk and surface conduction. WAL due to topological surface states shows no dependence on the nature (electrons or holes) of the bulk charge carriers. The observations of an extremely large nonsaturating magnetoresistance and ultrahigh mobility in the samples with lower carrier density further support the presence of surface states. The physical parameters characterizing the WAL effects are calculated using the Hikami-Larkin-Nagaoka formula. At high charge-carrier concentrations, there is a greater number of conduction channels and a decrease in the phase coherence length compared to low charge-carrier concentrations. The extremely large magnetoresistance and high mobility of topological insulators have great technological value and can be exploited in magnetoelectric sensors and memory devices.

  19. Effect of Bi on the corrosion resistance of zirconium alloys

    International Nuclear Information System (INIS)

    Yao Meiyi; Zhou Bangxin; Li Qiang; Zhang Weipeng; Zhu Li; Zou Linghong; Zhang Jinlong; Peng Jianchao

    2014-01-01

    In order to investigate systematically the effect of Bi addition on the corrosion resistance of zirconium alloys, different zirconium-based alloys, including Zr-4 (Zr-l.5Sn-0.2Fe-0.1Cr), S5 (Zr-0.8Sn-0.35Nb-0.4Fe-0.1Cr), T5 (Zr-0.7Sn-l.0Nb-0.3Fe-0.1Cr) and Zr-1Nb, were adopted to prepare the zirconium alloys containing Bi of 0∼0.5% in mass fraction. These alloys were denoted as Zr-4 + xBi, S5 + xBi, T5 + xBi and Zr-1Nb + xBi, respectively. The corrosion behavior of these specimens was investigated by autoclave testing in lithiated water with 0.01 M LiOH or deionized water at 360 ℃/18.6 MPa and in superheated steam at 400 ℃/10.3 MPa. The microstructure of the alloys was examined by TEM and the second phase particles (SPPs) were analyzed by EDS. Microstructure observation shows that the addition of Bi promotes the precipitation of Sn as second phase particles (SPPs) because Sn is in solid solution in α-Zr matrix in Zr-4, S5 and T5 alloys. The concentration of Bi dissolved in α-Zr matrix increase with the increase of Nb in the alloys, and the excess Bi precipitates as Bi-containing SPPs. The corrosion results show that the effect of Bi addition on the corrosion behavior of different zirconium-based alloys is very complicated, depending on their compositions and corrosion conditions. In the case of higher Bi concentration in α-Zr, the zirconium alloys exhibit better corrosion resistance. However, in the case of precipitation of Bi-containing SPPs, the corrosion resistance gets worse. This indicates that the solid solution of Bi in α-Zr matrix can improve the corrosion resistance, while the precipitation of the Bi-containing SPPs is harmful to the corrosion resistance. (authors)

  20. Dirac state in a centrosymmetric superconductor α -PdBi2

    Science.gov (United States)

    Dimitri, Klauss; Hosen, M. Mofazzel; Dhakal, Gyanendra; Choi, Hongchul; Kabir, Firoza; Sims, Christopher; Kaczorowski, Dariusz; Durakiewicz, Tomasz; Zhu, Jian-Xin; Neupane, Madhab

    2018-04-01

    Topological superconductor (TSC) hosting Majorana fermions has been established as a milestone that may shift our scientific trajectory from research to applications in topological quantum computing. Recently, superconducting Pd-Bi binaries have attracted great attention as a possible medium for the TSC phase as a result of their large spin-orbit coupling strength. Here, we report a systematic high-resolution angle-resolved photoemission spectroscopy (ARPES) study on the normal state electronic structure of superconducting α -PdBi2 (Tc=1.7 K). Our results show the presence of Dirac states at higher-binding energy with the location of the Dirac point at 1.26 eV below the chemical potential at the zone center. Furthermore, the ARPES data indicate multiple band crossings at the chemical potential, consistent with the metallic behavior of α -PdBi2 . Our detailed experimental studies are complemented by first-principles calculations, which reveal the presence of surface Rashba states residing in the vicinity of the chemical potential. The obtained results provide an opportunity to investigate the relationship between superconductivity, topology, and the Majorana fermion, as well as explore pathways to possible future platforms for topological quantum computing.

  1. Structural determination of Bi-doped magnetite multifunctional nanoparticles for contrast imaging.

    Science.gov (United States)

    Laguna-Marco, M A; Piquer, C; Roca, A G; Boada, R; Andrés-Vergés, M; Veintemillas-Verdaguer, S; Serna, C J; Iadecola, A; Chaboy, J

    2014-09-14

    To determine with precision how Bi atoms are distributed in Bi-doped iron oxide nanoparticles their structural characterization has been carried out by X-ray absorption spectroscopy (XAS) recorded at the K edge of Fe and at the L3 edge of Bi. The inorganic nanoparticles are nominally hybrid structures integrating an iron oxide core and a bismuth oxide shell. Fe K-edge XAS indicates the formation of a structurally ordered, non-stoichiometric magnetite (Fe3-δO4) phase for all the nanoparticles. The XAS spectra show that, in the samples synthesized by precipitation in aqueous media and laser pyrolysis, the Bi atoms neither enter into the iron oxide spinel lattice nor form any other mixed Bi-Fe oxides. No modification of the local structure around the Fe atoms induced by the Bi atoms is observed at the Fe K edge. In addition, contrary to expectations, our results indicate that the Bi atoms do not form a well-defined Bi oxide structure. The XAS study at the Bi L3 edge indicates that the environment around Bi atoms is highly disordered and only a first oxygen coordination shell is observed. Indefinite [BiO6-x(OH)x] units (isolated or aggregated forming tiny amorphous clusters) bonded through hydroxyl bridges to the nanoparticle, rather than a well defined Bi2O3 shell, surround the nanoparticle. On the other hand, the XAS study indicates that, in the samples synthesized by thermal decomposition, the Bi atoms are embedded in a longer range ordered structure showing the first and second neighbors.

  2. LaBiTe3: An unusual thermoelectric material

    KAUST Repository

    Singh, Nirpendra

    2014-06-18

    Using first-principles calculations and semi-classical Boltzmann transport theory, the thermoelectric properties of LaBiTe3 are studied. The band gap and, hence, the thermoelectric response are found to be easily tailored by application of strain. Independent of the temperature, the figure of merit turns out to be maximal at a doping of about 1.6 × 1021 cm-3. At room temperature we obtain values of 0.4 and 0.5 for unstrained and moderately strained LaBiTe3, which increases to 1.1 and 1.3 at 800 K. A large spin splitting is observed in the conduction band at the T point. Therefore, LaBiTe3 merges characteristics that are interesting for thermoelectric as well as spintronic devices.

  3. LaBiTe3: An unusual thermoelectric material

    KAUST Repository

    Singh, Nirpendra; Schwingenschlö gl, Udo

    2014-01-01

    Using first-principles calculations and semi-classical Boltzmann transport theory, the thermoelectric properties of LaBiTe3 are studied. The band gap and, hence, the thermoelectric response are found to be easily tailored by application of strain. Independent of the temperature, the figure of merit turns out to be maximal at a doping of about 1.6 × 1021 cm-3. At room temperature we obtain values of 0.4 and 0.5 for unstrained and moderately strained LaBiTe3, which increases to 1.1 and 1.3 at 800 K. A large spin splitting is observed in the conduction band at the T point. Therefore, LaBiTe3 merges characteristics that are interesting for thermoelectric as well as spintronic devices.

  4. PRECONDITIONED BI-CONJUGATE GRADIENT METHOD FOR RADIATIVE TRANSFER IN SPHERICAL MEDIA

    International Nuclear Information System (INIS)

    Anusha, L. S.; Nagendra, K. N.; Paletou, F.; Leger, L.

    2009-01-01

    A robust numerical method called the Preconditioned Bi-Conjugate Gradient (Pre-BiCG) method is proposed for the solution of the radiative transfer equation in spherical geometry. A variant of this method called Stabilized Preconditioned Bi-Conjugate Gradient (Pre-BiCG-STAB) is also presented. These are iterative methods based on the construction of a set of bi-orthogonal vectors. The application of the Pre-BiCG method in some benchmark tests shows that the method is quite versatile, and can handle difficult problems that may arise in astrophysical radiative transfer theory.

  5. Bi-directional ultrasonic wave coupling to FBGs in continuously bonded optical fiber sensing.

    Science.gov (United States)

    Wee, Junghyun; Hackney, Drew; Bradford, Philip; Peters, Kara

    2017-09-01

    Fiber Bragg grating (FBG) sensors are typically spot-bonded onto the surface of a structure to detect ultrasonic waves in laboratory demonstrations. However, to protect the rest of the optical fiber from any environmental damage during real applications, bonding the entire length of fiber, called continuous bonding, is commonly done. In this paper, we investigate the impact of continuously bonding FBGs on the measured Lamb wave signal. In theory, the ultrasonic wave signal can bi-directionally transfer between the optical fiber and the plate at any adhered location, which could potentially produce output signal distortion for the continuous bonding case. Therefore, an experiment is performed to investigate the plate-to-fiber and fiber-to-plate signal transfer, from which the signal coupling coefficient of each case is theoretically estimated based on the experimental data. We demonstrate that the two coupling coefficients are comparable, with the plate-to-fiber case approximately 19% larger than the fiber-to-plate case. Finally, the signal waveform and arrival time of the output FBG responses are compared between the continuous and spot bonding cases. The results indicate that the resulting Lamb wave signal output is only that directly detected at the FBG location; however, a slight difference in signal waveform is observed between the two bonding configurations. This paper demonstrates the practicality of using continuously bonded FBGs for ultrasonic wave detection in structural health monitoring (SHM) applications.

  6. Bi3+–Pr3+ energy transfer processes and luminescent properties of LuAG:Bi,Pr and YAG:Bi,Pr single crystalline films

    International Nuclear Information System (INIS)

    Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Zorenko, T.; Nikl, M.; Mares, J.A.; Beitlerova, A.; Jary, V.

    2013-01-01

    Absorption, cathodoluminescence, excitation spectra of photoluminescence (PL) and PL decay kinetics were studied at 300 K for the double doped with Bi 3+ –Pr 3+ and separately doped with Bi 3+ and Pr 3+ Lu 3 Al 5 O 12 (LuAG) and Y 3 Al 5 O 12 (YAG) single crystalline film (SCF) phosphors grown by the liquid phase epitaxy method. The emission bands in the UV range arising from the intrinsic radiative transitions of Bi 3+ based centers, and emission bands in the visible range, related to the luminescence of excitons localized around Bi 3+ based centers, were identified both in Bi–Pr and Bi-doped LuAG and YAG SCFs. The energy transfer processes from the host lattice simultaneously to Bi 3+ and Pr 3+ ions and from Bi 3+ to Pr 3+ ions were investigated. Competition between Pr 3+ and Bi 3+ ions in the energy transfer processes from the LuAG and YAG hosts was evidenced. The strong decrease of the intensity of Pr 3+ luminescence both in LuAG:Pr and YAG:Pr SCFs phosphors, grown from Bi 2 O 3 flux, is observed due to the quenching influence of Bi 3+ flux related impurity. Due to overlap of the UV emission band of Bi 3+ centers with the f–d absorption bands of Pr 3+ ions in the UV range and the luminescence of excitons localized around Bi ions with the f–f absorption bands of Pr 3+ ions in the visible range, an effective energy transfer from Bi 3+ ions to Pr 3+ ions takes place in LuAG:Bi,Pr and YAG:Bi,Pr SCFs, resulting in the appearance of slower component in the decay kinetics of the Pr 3+ d–f luminescence. -- Highlights: • Bi and Pr doped film phosphor grown by liquid phase epitaxy method. • Energy transfer from Bi 3+ to Pr 3+ ions. • Strong quenching of the Pr 3+ luminescence by Bi 3+ co-dopant

  7. Growth and structure of thermally evaporated Bi{sub 2}Te{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rogacheva, E.I., E-mail: rogacheva@kpi.kharkov.ua [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine); Budnik, A.V. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine); Dobrotvorskaya, M.V.; Fedorov, A.G.; Krivonogov, S.I.; Mateychenko, P.V. [Institute for Single Crystals of NAS of Ukraine, 60 Lenin Prospect, Kharkov 61001 (Ukraine); Nashchekina, O.N.; Sipatov, A.Yu. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine)

    2016-08-01

    The growth mechanism, microstructure, and crystal structure of the polycrystalline n-Bi{sub 2}Te{sub 3} thin films with thicknesses d = 15–350 nm, prepared by thermal evaporation in vacuum onto glass substrates, were studied. Bismuth telluride with Te excess was used as the initial material for the thin film preparation. The thin film characterization was performed using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scan electron microscopy, and electron force microscopy. It was established that the chemical composition of the prepared films corresponded rather well to the starting material composition and the films did not contain any phases apart from Bi{sub 2}Te{sub 3}. It was shown that the grain size and the film roughness increased with increasing film thickness. The preferential growth direction changed from [00l] to [015] under increasing d. The X-ray photoelectron spectroscopy studies showed that the thickness of the oxidized surface layer did not exceed 1.5–2.0 nm and practically did not change in the process of aging at room temperature, which is in agreement with the results reported earlier for single crystals. The obtained data show that using simple and inexpensive method of thermal evaporation in vacuum and appropriate technological parameters, one can grow n-Bi{sub 2}Te{sub 3} thin films of a sufficiently high quality. - Highlights: • The polycrystalline n-Bi{sub 2}Te{sub 3} thin films were grown thermal evaporation onto glass. • The growth mechanism and film structure were studied by different structure methods. • The grain size and film roughness increased with increasing film thickness. • The growth direction changes from [00l] to [015] under film thickness increasing. • The oxidized layer thickness (1–2 nm) did not change under aging at room temperature.

  8. L-subshell ionization studies in Au and Bi for 19F and 28Si large-ion bombardment

    International Nuclear Information System (INIS)

    Padhi, H.C.; Dhal, B.B.; Nanal, V.; Prasad, K.G.; Tandon, P.N.; Trautmann, D.

    1996-01-01

    L x-ray production and subshell ionization cross sections of Au and Bi have been measured for the bombardment of 19 F and 28 Si ions in the energy range 30 endash 57 MeV and 36 endash 84 MeV, respectively. Comparison of the Lα x-ray production cross sections of Au with the earlier data by Malhi and Gray [Phys. Rev. A 44, 7199 (1991)] shows reasonable agreement for 19 F impact and their data are consistently higher for 28 Si at all energies. The measured Lα line energy shows a shift towards higher energy, which appears to be proportional to the square of the projectile atomic number at all impact energies. This shift suggests the presence of multiple ionization in the L and M shells with a simultaneous production of four M holes in Au at the impact energy of 3 MeVu -1 of 28 Si. The L-subshell ionization cross sections obtained from the measured x-ray production cross sections have been compared with the semiclassical approximation and perturbed stationary state theory with energy loss, Coulomb deflection, and relativistic correction for the electron motion calculations, which show large deviations for the L 1 subshell. The L 2 - and L 3 -subshell ionization cross sections are underestimated by both the theories by a factor of 1.2 endash 4.0 for 28 Si impact whereas for the 19 F case there is reasonable agreement for the L 3 cross section but the L 2 cross section is underestimated by 20 endash 30%. copyright 1996 The American Physical Society

  9. Synthesis, characterization and photoluminescence properties of Bi³⁺ co-doped CaSiO₃:Eu³⁺ nanophosphor.

    Science.gov (United States)

    Kumar, M Madesh; Krishna, R Hari; Nagabhushana, B M; Shivakumara, C

    2015-03-15

    Ceramic luminescent powders with the composition Ca(0.96-x)Eu0.04Bi(x)SiO3 (x=0.01-0.05) were prepared by solution combustion method. The nanopowders are characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) techniques. PXRD patterns of calcined (950°C for 3h) Ca(0.96-x)Eu0.04Bi(x)SiO3 powders exhibit monoclinic phase with mean crystallite sizes ranging from 28 to 48 nm. SEM micrographs show the products are foamy, agglomerated and fluffy in nature due to the large amount of gases liberated during combustion reaction. TEM micrograph shows the crystalline characteristics of the nanoparticles. Upon 280 nm excitation, the photoluminescence of the Ca(0.96-x)Eu0.04Bi(x)SiO3 particles show red emission at 611 nm corresponding to 5D0→7F2 transition. It is observed that PL intensity increases with Bi(3+) concentration. Our work demonstrates very interesting energy transfer from Bi(3+) to Eu(3+) in CaSiO3 host. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Structural properties of superconducting Bi-2223/Ag tapes

    Energy Technology Data Exchange (ETDEWEB)

    Gottschalck Andersen, L.

    2001-05-01

    The structural properties of silver clad high-T{sub c} superconducting ceramic tapes of (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) have been investigated by means of synchrotron X-ray diffraction (including the 3DXRD microscope setup), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDS). By synchrotron X-ray diffraction in situ studies of the phase development during the transformation of (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 1}Cu{sub 2}O{sub x} (Bi-2212) into Bi-2223, the stoichiometry changes and the texture have been performed during annealing in 8% O{sub 2} and in air. Furthermore, an annealing with two high temperature cycles has been performed to study the equilibrium phenomena. During heating (Ca,Sr){sub 2}PbO{sub 4} decomposes at temperatures between 700 deg. C and 840 deg.C. Simultaneously, the Bi-2212 lattice contracts, indicating an incorporation of Pb. Moreover, the grain mis-alignment decreases significantly. In air we have observed that Bi-2212 partly dissociates into (Ca,Sr){sub 2}CuO{sub 3} and a liquid at temperatures above 812 deg. C. At the annealing temperature Bi-2212 and (Ca,Sr){sub 2}CuO{sub 3} react with the liquid to form Bi-2223. The transformation mechanism is discussed. During cooling below {approx}750 deg.C (Ca,Sr){sub 2}CuO{sub 3} and the liquid mainly transform into Bi-2201. Below {approx}780 deg. C Bi-2223 decomposes to 3221. In addition, a two-step cooling experiment and a decomposition study have been performed in 8% O{sub 2}. By TEM the grain and colony size in the c-axis direction, the angles of c-axis tilt grain boundaries and the intergrowth content are investigated. A fully processed tape has on average 50% thicker grains than a tape after the 1st annealing. The angles of c-axis tilt grain boundaries are on average 14 deg. and 26 deg. for the fully processed tape and the tape after the 1st annealing, respectively. The intergrowth content (15%) and

  11. XPS and DFT study of pulsed Bi-implantation of bulk and thin-films of ZnO—The role of oxygen imperfections

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, D.A. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Boukhvalov, D.W., E-mail: danil@hanyang.ac.kr [Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 04763 (Korea, Republic of); Theoretical Physics and Applied Mathematics Department, Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Gavrilov, N.V. [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 620990 Yekaterinburg (Russian Federation); Kurmaev, E.Z. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Zhidkov, I.S. [Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation)

    2016-11-30

    Highlights: • Both theory and experiment evidence similarity of patterns of Bi-implantation in surface and bulk ZnO. • In the bulk morphology of ZnO both experiment and theory demonstrate preferability of substitutional defects. • Experiment and theory also evidence the formation of bismuth nano-clustes from substitutional and interstitial defects without formation of secondary metallic phase. • Oxygen vacancies is crucial to formation of these nano-clusters. - Abstract: An atomic and electronic structure of the bulk and thin-film morphologies of ZnO were modified using pulsed Bi-ion implantation (1 × 10{sup 17} cm{sup −2} fluence, 70 min exposure under Bi-ion beam, E{sub Bi}{sup +} = 30 keV, pulsed ion-current density of not more than 0.8 mA/cm{sup 2} with a repetition rate of 12.5 Hz). The final samples were qualified by X-ray photoelectron core-level and valence band mapping spectroscopy applying ASTM materials science standard. The spectroscopy data obtained was discussed on the basis of DFT-models for Bi-embedding into ZnO host-matrices. It was established that in the case of direct Bi-impurities insertion into the employed ZnO-host for both studied morphologies neither the only “pure” Bi{sub 2}O{sub 3}-like phase nor the only “pure” Bi-metal will be preferable to appear as a secondary phase. An unfavorability of the large cluster agglomeration of Bi-impurities in ZnO-hosts has been shown and an oxygen 2s electronic states pleomorphizm was surely established.

  12. Nanoscale Control of Exchange Bias with BiFeO3 Thin Films

    NARCIS (Netherlands)

    Martin, Lane W.; Chu, Ying-Hao; Holcomb, Mikel B.; Huijben, Mark; Yu, Pu; Han, Shu-Jen; Lee, Donkoun; Wang, Shan X.; Ramesh, R.

    2008-01-01

    We demonstrate a direct correlation between the domain structure of multiferroic BiFeO3 thin films and exchange bias of Co0.9Fe0.1/BiFeO3 heterostructures. Two distinct types of interactions − an enhancement of the coercive field (exchange enhancement) and an enhancement of the coercive field

  13. InP-DHBT-on-BiCMOS technology with fT/fmax of 400/350 GHz for heterogeneous integrated millimeter-wave sources

    DEFF Research Database (Denmark)

    Kraemer, Tomas; Ostermay, Ina; Jensen, Thomas

    2013-01-01

    -100 GHz. The 0.8 × 5 μm2 InP DHBTs show fT/fmax of 400/350 GHz with an output power of more than 26 mW at 96 GHz. These are record values for a heterogeneously integrated transistor on silicon. As a circuit example, a 164-GHz signal source is presented. It features a voltage-controlled oscillator in Bi......This paper presents a novel InP-SiGe BiCMOS technology using wafer-scale heterogeneous integration. The vertical stacking of the InP double heterojunction bipolar transistor (DHBT) circuitry directly on top of the BiCMOS wafer enables ultra-broadband interconnects with

  14. A validation of a ray-tracing tool used to generate bi-directional scattering distribution functions for complex fenestration systems

    DEFF Research Database (Denmark)

    McNeil, A.; Jonsson, C.J.; Appelfeld, David

    2013-01-01

    , or daylighting systems. However, such tools require users to provide bi-directional scattering distribution function (BSDF) data that describe the solar-optical performance of the CFS. A free, open-source Radiance tool genBSDF enables users to generate BSDF data for arbitrary CFS. Prior to genBSDF, BSDF data.......We explain the basis and use of the genBSDF tool and validate the tool by comparing results for four different cases to BSDF data produced via alternate methods. This validation demonstrates that BSDFs created with genBSDF are comparable to BSDFs generated analytically using TracePro and by measurement...

  15. The physic properties of Bi-Zn codoped Y-type hexagonal ferrite

    International Nuclear Information System (INIS)

    Bai Yang; Zhou Ji; Gui Zhilun; L, Longtu; Qiao Lijie

    2008-01-01

    The magnetic and dielectric properties of Bi-Zn codoped Y-type hexagonal ferrite was investigated. The samples with composition of Ba 2-x Bi x Zn 0.8+x Co 0.8 Cu 0.4 Fe 12-x O 22 (x = 0-0.4) were prepared by the solid-state reaction method. Phase formation was characterized by X-ray diffraction. The microstructure was observed via scanning electron microscopy. The magnetic and dielectric properties were measured using an impedance analyzer. Direct current (dc) electrical resistivity was measured using a pA meter/dc voltage source. Minor Bi doping (x = 0.05-0.25) will not destroy the phase formation of Y-type hexagonal ferrite, but lower the phase formation temperature distinctly. Bi substitution can also promote the sintering process. The Bi-containing samples (x > 0.05) can be sintered well under 900 deg. C without any other addition. The sintering temperature is about 200 deg. C lower than that of the Bi-free sample. The Bi-Zn codoped samples exhibit excellent magnetic and dielectric properties in hyper frequency. These materials are suitable for multi-layer chip-inductive components

  16. A novel perovskite oxide chemically designed to show multiferroic phase boundary with room-temperature magnetoelectricity

    Science.gov (United States)

    Fernández-Posada, Carmen M.; Castro, Alicia; Kiat, Jean-Michel; Porcher, Florence; Peña, Octavio; Algueró, Miguel; Amorín, Harvey

    2016-09-01

    There is a growing activity in the search of novel single-phase multiferroics that could finally provide distinctive magnetoelectric responses at room temperature, for they would enable a range of potentially disruptive technologies, making use of the ability of controlling polarization with a magnetic field or magnetism with an electric one (for example, voltage-tunable spintronic devices, uncooled magnetic sensors and the long-searched magnetoelectric memory). A very promising novel material concept could be to make use of phase-change phenomena at structural instabilities of a multiferroic state. Indeed, large phase-change magnetoelectric response has been anticipated by a first-principles investigation of the perovskite BiFeO3-BiCoO3 solid solution, specifically at its morphotropic phase boundary between multiferroic polymorphs of rhombohedral and tetragonal symmetries. Here, we report a novel perovskite oxide that belongs to the BiFeO3-BiMnO3-PbTiO3 ternary system, chemically designed to present such multiferroic phase boundary with enhanced ferroelectricity and canted ferromagnetism, which shows distinctive room-temperature magnetoelectric responses.

  17. Bi:Ge substitution - its effect on the structural and electrical properties of the Bi2212 superconductor

    International Nuclear Information System (INIS)

    Saligan, P.P.

    1997-03-01

    The critical temperature determined from dc resistance and ac magnetic susceptibility measurements, and the coherence length obtained from the of fluctuation conductivity of polycrystalline Bi 2-x Ge x Sr 2 CaCu 2 O 8 +δ were studied. The effect of sample quality was also studied by making two kinds of pellet samples: (1) by conventional sintering process and (2) by conventional sintering process followed annealing at high temperature. The rough phase diagram of Bi 2-x Ge x Sr 2 CaCu 2 O 8 +δ was constructed and it was found that from x=0 to x=0.3 a predominantly Bi2212 phase can be obtained. The critical temperature of the unsubstituted Bi 2 Sr 2 CaCu 2 O 8 +δ is sensitive to the cold press and anneal method. The resistive transition T c based on the maximum dR(T)dT of the as-sintered Bi 2 Sr 2 CaCu 2 O 8 +δ is about 74 K. The resistive T c of the cold-pressed-annealed samples either (1) remain near 74 K or (2) increase to approximately 85 K or (3) show two values at about 74 K and 85 K. A structural relaxation is observed in the Bi 2-x Ge x Sr 2 CaCu 2 O 8 +δ the c-axis decreases with increasing x and the a-axis increases at x=0.1 then settles back to its unsubstituted value at higher x. The as-sintered samples show an increasing resistive T c with x, 74 K for x=0 and 79 K for x>0. The resistive T c 's of the cold-pressed-annealed samples are almost independent of x, 85 K for x=0 and 87 K for x>0. The increase in the magnetic critical temperature induced by the cold press and anneal method is considerably larger compared to the increase in the resistive critical temperature, independent of the Bi:Ge substitution. An analysis of fluctuation conductivity just above T c using the Aslamasov-Larkin model for two-dimensional superconductors and the Lawrence-Doniach model for layered superconductors was done. The Aslamasov-Larkin model gives the thickness of the two dimensional superconductor to be ∼34 A also independent of the Bi:Ge substitution. The Lawrence

  18. The Effect of Temperature Dependence of AC Losses in a Bi-2223/Ag Insert of an 8-T Superconducting Magnet

    DEFF Research Database (Denmark)

    Wang, Lei; Wang, Qiuliang; Wang, Hui

    2016-01-01

    A conduction-cooled split-gap superconducting magnet system with a center field of 8 T has been designed and fabricated in the Institute of Electrical Engineering, Chinese Academy of Sciences. The system consists of two Bi-2223/Ag coils and six NbTi coils. Due to a large aspect ratio of the high-...... in the second case. Hence, it is a good way to reduce the ac losses by changing the charging sequences of the Bi-2223/Ag and NbTi cols. Afterward, the calculated results are compared with the experimental data, and they show a good agreement.......A conduction-cooled split-gap superconducting magnet system with a center field of 8 T has been designed and fabricated in the Institute of Electrical Engineering, Chinese Academy of Sciences. The system consists of two Bi-2223/Ag coils and six NbTi coils. Due to a large aspect ratio of the high......-temperature superconducting tape, there will be large ac losses when the magnet is ramped up and down. An accurate estimation of the total ac losses in the high-temperature superconducting coils is essential for the cryogenic system design. In the Bi-2223/Ag coils, the total ac losses mainly originate from two parts: One...

  19. One-pot solvothermal synthesis of three-dimensional (3D) BiOI/BiOCl composites with enhanced visible-light photocatalytic activities for the degradation of bisphenol-A

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Xin [School of Chemistry and Environment, South China Normal University, Key Lab of Theoretical Chemistry of Environment, Guangzhou 510006 (China); Nano Science Research Center, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China); Hao, Rong; Liang, Min; Zuo, Xiaoxi [School of Chemistry and Environment, South China Normal University, Key Lab of Theoretical Chemistry of Environment, Guangzhou 510006 (China); Nan, Junmin, E-mail: jmnan@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Key Lab of Theoretical Chemistry of Environment, Guangzhou 510006 (China); Li, Laisheng [School of Chemistry and Environment, South China Normal University, Key Lab of Theoretical Chemistry of Environment, Guangzhou 510006 (China); Zhang, Weide [Nano Science Research Center, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer Synthesis of 3D BiOI/BiOCl microspheres by a one-pot template-free solvothermal method. Black-Right-Pointing-Pointer Photocatalyst is BiOI/BiOCl composites. Black-Right-Pointing-Pointer BiOI/BiOCl composites have enhanced visible-light photocatalytic ability to bisphenol-A. Black-Right-Pointing-Pointer A simple and direct photodegradation pathway of bisphenol-A is proposed. - Abstract: Three-dimensional (3D) BiOI/BiOCl composite microspheres with enhanced visible-light photodegradation activity of bisphenol-A (BPA) are synthesized by a simple, one-pot, template-free, solvothermal method using BiI{sub 3} and BiCl{sub 3} as precursors. These 3D hierarchical microspheres with heterojunction structures are composed of 2D nanosheets and have composition-dependent absorption properties in the ultraviolet and visible light regions. The photocatalytic oxidation of BPA over BiOI/BiOCl composites followed pseudo first-order kinetics according to the Langmuir-Hinshelwood model. The highest photodegradation efficiency of BPA, i.e., nearly 100%, was observed with the BiOI/BiOCl composite (containing 90% BiOI) using a catalyst dosage of 1 g L{sup -1} in the BPA solution (C{sub 0} = 20 mg L{sup -1}, pH = 7.0) under visible light irradiation for 60 min. Under these conditions, the reaction rate constant was more than 4 and 20 times greater than that of pure BiOI and the commercially available Degussa P25, respectively. The superior photocatalytic activity of this composite catalyst is attributed to the suitable band gap energies and the low recombination rate of the photogenerated electron-hole pairs due to the presence of BiOI/BiOCl heterostructures. Only one intermediate at m/z 151 was observed in the photodegradation process of BPA by liquid chromatography combined with mass spectrometry (LC-MS) analysis, and a simple and hole-predominated photodegradation pathway of BPA was subsequently proposed. Furthermore, this photocatalyst

  20. Improved photoelectrochemical performance of Z-scheme g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} heterostructure and degradation property

    Energy Technology Data Exchange (ETDEWEB)

    Li, Junqi, E-mail: sfmlab@163.com; Yuan, Huan; Zhu, Zhenfeng

    2016-11-01

    Highlights: • A novel Z-scheme g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} composite was synthesized. • The Z-scheme system we made can remain the strong reducibility and oxidizability of the photocatalysts. • The solar light was made the utmost use both the ultraviolet and visible region light through the g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} composite. - Abstract: In g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}, the p–n junction between p-type Bi{sub 2}O{sub 3} and n-type BiPO{sub 4} was encapsulated by g-C{sub 3}N{sub 4} and a direct Z-scheme was built between g-C{sub 3}N{sub 4} and Bi{sub 2}O{sub 3}. The optical, morphological and photoelectrochemical (PEC) properties of BiPO{sub 4}, g-C{sub 3}N{sub 4}/BiPO{sub 4}, Bi{sub 2}O{sub 3}/BiPO{sub 4} and g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4} hierarchical Z-scheme system were studied. More than 90% photodegradation of methyl orange (MO) with the exposure of simulated solar light was achieved within 160 min with the g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}, which displayed remarkably promoted photocatalytic activities than other samples. The electrochemical impedance spectra and photocurrent results also proved that efficient charge separation and better electron transport properties were achieved by g-C{sub 3}N{sub 4}/Bi{sub 2}O{sub 3}/BiPO{sub 4}. In general, the addition of g-C{sub 3}N{sub 4} can guide the residual electrons on p-type Bi{sub 2}O{sub 3} to recombine with photoholes of g-C{sub 3}N{sub 4} and make sure the left carries exhibit stronger oxidation and reduction ability to boost the production of active groups.

  1. Accurate torque control of a bi-directional magneto-rheological actuator considering hysteresis and friction effects

    International Nuclear Information System (INIS)

    Nguyen, Phuong-Bac; Choi, Seung-Bok

    2013-01-01

    This paper presents a novel type of magneto-rheological (MR) actuator called a bi-directional magneto-rheological (BMR) actuator and accurate torque control results considering both hysteresis and friction compensation. The induced torque of this actuator varies from negative to positive values. As a result, it can work as either a brake or a clutch depending on the scheme of current input. In our work, the configuration of the actuator as well as its driving system is presented first. Subsequently, a congruency hysteresis based (CBH) model to take account of the effect of the hysteresis is proposed. After that, a compensator based on this model is developed. In addition, the effect of dry friction, which exists inherently with MR actuators in general, is also considered. In order to assess the effectiveness of the hysteresis compensator, several experiments on modeling and control of the actuator with different waveforms are carried out. (paper)

  2. Accurate torque control of a bi-directional magneto-rheological actuator considering hysteresis and friction effects

    Science.gov (United States)

    Nguyen, Phuong-Bac; Choi, Seung-Bok

    2013-05-01

    This paper presents a novel type of magneto-rheological (MR) actuator called a bi-directional magneto-rheological (BMR) actuator and accurate torque control results considering both hysteresis and friction compensation. The induced torque of this actuator varies from negative to positive values. As a result, it can work as either a brake or a clutch depending on the scheme of current input. In our work, the configuration of the actuator as well as its driving system is presented first. Subsequently, a congruency hysteresis based (CBH) model to take account of the effect of the hysteresis is proposed. After that, a compensator based on this model is developed. In addition, the effect of dry friction, which exists inherently with MR actuators in general, is also considered. In order to assess the effectiveness of the hysteresis compensator, several experiments on modeling and control of the actuator with different waveforms are carried out.

  3. Fabrication and characterization of Bi2Sr2CaCu2O8+δ stacks by self-planarizing process

    International Nuclear Information System (INIS)

    Okanoue, K.; Ishida, H.; Funabiki, H.; Hamasaki, K.; Shimakage, N.; Kawakami, A.; Wang, Z.; Abe, H.

    2005-01-01

    We developed a new fabrication process of stacked intrinsic Josephson junctions using superconducting Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212) single crystals. In the proposed self-planarizing process, the Bi-2212 crystal around the junction window was modified to insulator by soaking into the solution of dilute (0.05-0.2%) hydrochloric acid for 5 s. Energy dispersive X-ray (EDX) spectroscopy revealed that the acid-treated Bi-2212 exhibited the decrease of Cu and Sr contents in the crystals. The current-voltage characteristic of the stacks showed distinct resistive branches with large hysteresis at 77 K. The number of intrinsic junctions in the stacks linearly decreased with decreasing the concentration of the solution. The well controllability of the number of junctions in the self-planarized stacks may be useful for electronic device applications

  4. Facile synthesis of flower-like BiOI hierarchical spheres at room temperature with high visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Wang, Xiao-jing; Li, Fa-tang; Li, Dong-yan; Liu, Rui-hong; Liu, Shuang-jun

    2015-01-01

    Graphical abstract: - Highlights: • Flower-like BiOI hierarchical sphere is obtained in the presence of ethylene glycol. • A template free hydrolysis route is employed at room temperature. • Ethylene glycol plays an important role in assembling BiOI nanoflakes to form spheres. • The BiOI sphere shows high visible-light photocatalytic activity and good stability. - Abstract: Flower-like BiOI hierarchical spheres are prepared at room temperature via a template free route simply by dropping water into ethylene glycol (EG) solution containing reactants based on the hydrolysis and oriented assembly roles of water and EG, respectively. The BiOI samples are characterized by X-ray diffraction (XRD), nitrogen adsorption/desorption, emission scanning electron microscopy (SEM), UV–Vis diffuse reflectance spectra (UV–Vis DRS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The photocatalytic reaction rate constant of the as-prepared BiOI hierarchical spheres is 15.8, 13.3, and 2.0 times that of BiOI nanoflakes obtained in the absence of EG in degradation of anionic dye (methyl orange), cationic dye (methylene blue), and colorless target pollutant (phenol), respectively, under the visible-light irradiation, which can be attributed to its unique flower-like structure for utilization of light, small crystal size, and large specific surface area

  5. Large power factor and anomalous Hall effect and their correlation with observed linear magneto resistance in Co-doped Bi2Se3 3D topological insulator

    Science.gov (United States)

    Singh, Rahul; Shukla, K. K.; Kumar, A.; Okram, G. S.; Singh, D.; Ganeshan, V.; Lakhani, Archana; Ghosh, A. K.; Chatterjee, Sandip

    2016-09-01

    Magnetoresistance (MR), thermo power, magnetization and Hall effect measurements have been performed on Co-doped Bi2Se3 topological insulators. The undoped sample shows that the maximum MR as a destructive interference due to a π-Berry phase leads to a decrease of MR. As the Co is doped, the linearity in MR is increased. The observed MR of Bi2Se3 can be explained with the classical model. The low temperature MR behavior of Co doped samples cannot be explained with the same model, but can be explained with the quantum linear MR model. Magnetization behavior indicates the establishment of ferromagnetic ordering with Co doping. Hall effect data also supports the establishment of ferromagnetic ordering in Co-doped Bi2Se3 samples by showing the anomalous Hall effect. Furthermore, when spectral weight suppression is insignificant, Bi2Se3 behaves as a dilute magnetic semiconductor. Moreover, the maximum power factor is observed when time reversal symmetry (TRS) is maintained. As the TRS is broken the power factor value is decreased, which indicates that with the rise of Dirac cone above the Fermi level the anomalous Hall effect and linearity in MR increase and the power factor decreases.

  6. Adsorption and photocatalytic degradation of pharmaceuticals by BiOCl{sub x}I{sub y} nanospheres in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoning; Bi, Wenlong; Zhai, Pingping [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China); Wang, Xiaobing [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF)-ENSCCF, BP 10448, F-63000 Clermont-Ferrand (France); Li, Hongjing, E-mail: lihongjing@fudan.edu.cn [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China); Mailhot, Gilles [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand (ICCF)-ENSCCF, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, F-63171 Aubière (France); Dong, Wenbo, E-mail: wbdong@fudan.edu.cn [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China)

    2016-01-01

    Graphical abstract: - Highlights: • BiOCl{sub x}I{sub y} nanospheres were synthesised by precipitation method in EG-H{sub 2}O. • BiOCl{sub x}I{sub y} catalyst possessed high surface area and small particle size. • BiOCl{sub 0.75}I{sub 0.25} showed the best photocatalytic ability of p-HPA and ACTP. • Degradation of p-HPA and ACTP primarily proceeded by O{sub 2}·{sup −}. - Abstract: BiOCl{sub x}I{sub y} nanospheres have been synthesised via precipitation method in ethylene glycol (EG)-water (H{sub 2}O) mixed solvent at 80 °C and ambient pressure. Results of BiOCl{sub x}I{sub y} characterisation showed that these composite materials well combined BiOCl with BiOI crystals, which displayed flower-like hierarchical nanospheres consisted of numerous nanosheets and possessed smaller particle size, higher surface area than those in previous papers. The great surface area resulted in its high adsorption abilities of hydroxyphenylacetic acid (p-HPA) in the dark, the adsorption process could be suitably described by a pseudo-second-order kinetics model and the adsorption isotherms could be well fitted with Freundlich and Langmuir equations. The photocatalytic degradation of p-HPA and acetaminophen (ACTP) were investigated under simulated solar and visible irradiation using BiOCl{sub x}I{sub y} catalyst for the first time. The combination of BiOCl and BiOI to a certain extent has largely improved the remove efficiency, and BiOCl{sub 0.75}I{sub 0.25} was the optimal catalyst with almost 100% removal of p-HPA and 80% removal of ACTP under solar light for 3 h. Experimental results demonstrated that the photocatalytic degradation of p-HPA and ACTP followed pseudo-first-order kinetics and O{sub 2}·{sup −} and dissolved oxygen play predominant roles in photocatalytic process efficiency. This research will supply an environment-friendly photocatalyst for pharmaceutical wastewater treatment under sunlight.

  7. Modeling of Ammonia Dry Deposition to a Pocosin Landscape Downwind of a Large Poultry Facility

    Science.gov (United States)

    A semi-empirical bi-directional flux modeling approach is used to estimate NH3 air concentrations and dry deposition fluxes to a portion of the Pocosin Lakes National Wildlife Refuge (PLNWR) downwind of a large poultry facility. Meteorological patterns at PLNWR are such that som...

  8. Perovskite BaBiO3 Transformed Layered BaBiO2.5 Crystals Featuring Unusual Chemical Bonding and Luminescence.

    Science.gov (United States)

    Li, Hong; Zhao, Qing; Liu, Bo-Mei; Zhang, Jun-Ying; Li, Zhi-Yong; Guo, Shao-Qiang; Ma, Ju-Ping; Kuroiwa, Yoshihiro; Moriyoshi, Chikako; Zheng, Li-Rong; Sun, Hong-Tao

    2018-04-14

    Engineering oxygen coordination environments of cations in oxides has received intense interest thanks to the opportunities for the discovery of novel oxides with unusual properties. Here we present the successful synthesis of stoichiometric layered BaBiO2.5 enabled by a non-topotactic phase transformation of perovskite BaBiO3. By analysing the synchrotron X-ray diffraction data using the maximum entropy method/Rietveld technique, we find that Bi forms unusual chemical bondings with four oxygen atoms, featuring one ionic bonding and three covalent bondings that results in an asymmetric coordination geometry. A broad range of photophysical characterizations reveal that this peculiar structure shows near-infrared luminescence differing from conventional Bi-bearing systems. Experimental and theoretical results lead us to propose the excitonic nature of luminescence. Our work highlights that synthesizing materials with uncommon Bi-O bonding and Bi coordination geometry provides a pathway to the discovery of systems with new functionalities. We envisage that this work could inspire interest for the exploration of a range of materials containing heavier p-block elements, offering prospects for the finding of systems with unusual properties. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Comparison of ultraviolet Bi-directional Reflectance Distribution Function (BRDF) measurements of diffusers used in the calibration of the Total Ozone Mapping Spectrometer (TOMS)

    OpenAIRE

    Butler, J.J.; Park, H.; Barnes, P.Y.; Early, E.A.; Eijk-Olij, C. van; Zoutman, A.E.; Buller-Leeuwen, S. van; Groote Schaarsberg, J.

    2002-01-01

    The measurement and long-term monitoring of global total ozone by ultraviolet albedo measuring satellite instruments require accurate and precise determination of the Bi-directional Reflectance Distribution Function (BRDF) of laboratory-based diffusers used in the pre-launch calibration of those instruments. To assess the ability of laboratories to provide accurate Ultra Violet (UV) diffuse BRDF measurements, a BRDF measurement comparison was initiated by the NASA Total Ozone Mapping Spectrom...

  10. State diagram of Pr-Bi system

    International Nuclear Information System (INIS)

    Abulkhaev, V.L.; Ganiev, I.N.

    1994-01-01

    By means of thermal differential analysis, X-ray and microstructural analysis the state diagram of Pr-Bi system was studied. Following intermetallic compounds were defined in the system: Pr 2 Bi, Pr 5 Bi 3 , Pr 4 Bi 3 , Pr Bi, PrBi 2 , Pr 2 Bi, Pr 5 Bi 3 , Pr 4 Bi 3 and PrBi 2 . The data analysis on Ln-Bi diagram allowed to determine the regularity of change of properties of intermetallic compounds in the line of rare earth elements of cerium subgroup.

  11. Photocatalytic removal of tetrabromobisphenol A by magnetically separable flower-like BiOBr/BiOI/Fe{sub 3}O{sub 4} hybrid nanocomposites under visible-light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Shengwang [Department of Chemistry, College of Science, North University of China, Taiyuan 030051 (China); State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Guo, Changsheng; Hou, Song; Wan, Li [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Wang, Qiang [Heilongjiang Research Academy of Environmental Sciences, Harbin 150056 (China); Lv, Jiapei; Zhang, Yuan [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Gao, Jianfeng [Department of Chemistry, College of Science, North University of China, Taiyuan 030051 (China); Meng, Wei [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Xu, Jian, E-mail: xujian@craes.org.cn [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)

    2017-06-05

    Highlights: • A novel BiOBr/BiOI/Fe{sub 3}O{sub 4} hybrid nanocomposites was prepared for the first time. • BiOBr-BiOI-Fe{sub 3}O{sub 4} (2:2:0.5) displays superior photocatalytic activity for TBBPA. • Good magnetic property makes it easy for the material’s recovery from solution. • The photocatalytic reaction mechanism of BiOBr/BiOI/Fe{sub 3}O{sub 4} was proposed. • Superoxide radical is the dominant ROS in TBBPA degradation. - Abstract: A novel flower-like three-dimensional BiOBr/BiOI/Fe{sub 3}O{sub 4} heterojunction photocatalyst was synthesized using a simple in situ co-precipitation method at room temperature. The hybrid composites were characterized by a couple of techniques including X-ray powder diffraction, scanning electron microscope, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, Brunauer-Emmett-Teller, X-ray photo-electron spectroscopy, photoluminescence technique, and vibrating sample magnetometer. Fe{sub 3}O{sub 4} nanoparticles were perfectly loaded on the surface of BiOBr/BiOI microspheres. The recyclable magnetic BiOBr/BiOI/Fe{sub 3}O{sub 4} was employed to degrade TBBPA under visible light irradiation. The optimal removal efficiency of the ternary BiOBr/BiOI/Fe{sub 3}O{sub 4} (2:2:0.5) nanocomposite reached up to 98.5% for TBBPA in aqueous solution. The superior photocatalytic activity of BiOBr/BiOI/Fe{sub 3}O{sub 4} was mainly ascribed to large surface area and appropriate energy gaps, resulting in the effective adsorption and separation of electrons-hole pairs. The photogenerated reactive species determined by free radicals trapping experiments revealed that the excellent catalytic activity was primarily driven by ·O{sub 2}{sup −} radical. The photocatalytic degradation kinetics and a detailed mechanism were also proposed. Result demonstrated that the BiOBr/BiOI/Fe{sub 3}O{sub 4} can be magnetically recycled, and maintain high photocatalytic activity after reuse over five cycles. It

  12. Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells

    International Nuclear Information System (INIS)

    Yu, Zhongwei; Lu, Jiawen; Qian, Shengyi; Xu, Jun; Xu, Ling; Wang, Junzhuan; Shi, Yi; Chen, Kunji; Misra, Soumyadeep; Roca i Cabarrocas, Pere; Yu, Linwei

    2015-01-01

    Low-melting point metals such as bismuth (Bi) and tin (Sn) are ideal choices for mediating a low temperature growth of silicon nanowires (SiNWs) for radial junction thin film solar cells. The incorporation of Bi catalyst atoms leads to sufficient n-type doping in the SiNWs core that exempts the use of hazardous dopant gases, while an easy morphology control with pure Bi catalyst has never been demonstrated so far. We here propose a Bi-Sn alloy catalyst strategy to achieve both a beneficial catalyst-doping and an ideal SiNW morphology control. In addition to a potential of further growth temperature reduction, we show that the alloy catalyst can remain quite stable during a vapor-liquid-solid growth, while providing still sufficient n-type catalyst-doping to the SiNWs. Radial junction solar cells constructed over the alloy-catalyzed SiNWs have demonstrated a strongly enhanced photocurrent generation, thanks to optimized nanowire morphology, and largely improved performance compared to the reference samples based on the pure Bi or Sn-catalyzed SiNWs

  13. On the synthesis and microstructure analysis of high performance MnBi

    Directory of Open Access Journals (Sweden)

    Yu-Chun Chen

    2016-12-01

    Full Text Available Highly anisotropic MnBi powder with over 90 wt% low-temperature phase can be prepared using conventional arc-melting and 2 hour-low energy ball milling (BM followed by magnetic separation. After proper alignment, the purified Mn55Bi45(Mn45Bi55 powder show remarkable magnetic properties: mass remanence of 71(65 Am2/kg and coercivity of 1.23(1.18 T at 300 K. The nominal maximum energy product of 120 kJ/m3 is achieved in the purified 2h-BM Mn55Bi45 powder, close to theoretical value of 140.8 kJ/m3. The Mn55Bi45(Mn45Bi55 bulk magnets show the highest volume remanence of 0.68(0.57 T at 300 K, while they were consolidated at 573(523 K by a pressure of 200 MPa for 5 minutes using hot-compaction method. In addition to the observed grain size, the coercivity of the hot-compacted samples at 300 K was found to be strongly related to the amount of metallic Mn and Bi residue at the grain-boundary. Our study proves that the magnetic properties of the Mn45Bi55 bulk magnets are stable up to 500 K, and the nominal (BHmax values are still above 40 kJ/m3 at 500 K showing the potential ability for high-temperature applications.

  14. Weak antilocalization effect and noncentrosymmetric superconductivity in a topologically nontrivial semimetal LuPdBi

    KAUST Repository

    Xu, Guizhou; Wang, Wenhong; Zhang, Xiaoming; Du, Yin; Liu, Enke; Wang, Shouguo; Wu, Guangheng; Liu, Zhongyuan; Zhang, Xixiang

    2014-01-01

    A large number of half-Heusler compounds have been recently proposed as three-dimensional (3D) topological insulators (TIs) with tunable physical properties. However, no transport measurements associated with the topological surface states have been observed in these half-Heusler candidates due to the dominating contribution from bulk electrical conductance. Here we show that, by reducing the mobility of bulk carriers, a two-dimensional (2D) weak antilocalization (WAL) effect, one of the hallmarks of topological surface states, was experimentally revealed from the tilted magnetic field dependence of magnetoconductance in a topologically nontrivial semimetal LuPdBi. Besides the observation of a 2D WAL effect, a superconducting transition was revealed at T c ∼ 1.7â.K in the same bulk LuPdBi. Quantitative analysis within the framework of a generalized BCS theory leads to the conclusion that the noncentrosymmetric superconductivity of LuPdBi is fully gapped with a possibly unconventional pairing character. The co-existence of superconductivity and the transport signature of topological surface states in the same bulk alloy suggests that LuPdBi represents a very promising candidate as a topological superconductor.

  15. Weak antilocalization effect and noncentrosymmetric superconductivity in a topologically nontrivial semimetal LuPdBi

    KAUST Repository

    Xu, Guizhou

    2014-07-21

    A large number of half-Heusler compounds have been recently proposed as three-dimensional (3D) topological insulators (TIs) with tunable physical properties. However, no transport measurements associated with the topological surface states have been observed in these half-Heusler candidates due to the dominating contribution from bulk electrical conductance. Here we show that, by reducing the mobility of bulk carriers, a two-dimensional (2D) weak antilocalization (WAL) effect, one of the hallmarks of topological surface states, was experimentally revealed from the tilted magnetic field dependence of magnetoconductance in a topologically nontrivial semimetal LuPdBi. Besides the observation of a 2D WAL effect, a superconducting transition was revealed at T c ∼ 1.7â.K in the same bulk LuPdBi. Quantitative analysis within the framework of a generalized BCS theory leads to the conclusion that the noncentrosymmetric superconductivity of LuPdBi is fully gapped with a possibly unconventional pairing character. The co-existence of superconductivity and the transport signature of topological surface states in the same bulk alloy suggests that LuPdBi represents a very promising candidate as a topological superconductor.

  16. Emergence of topological and topological crystalline phases in TlBiS2 and TlSbS2

    KAUST Repository

    Zhang, Qingyun

    2015-02-11

    Using first-principles calculations, we investigate the band structure evolution and topological phase transitions in TlBiS2 and TlSbS2 under hydrostatic pressure as well as uniaxial and biaxial strain. The phase transitions are identified by parity analysis and by calculating the surface states. Zero, one, and four Dirac cones are found for the (111) surfaces of both TlBiS2 and TlSbS2 when the pressure grows, which confirms trivial-nontrivial-trivial phase transitions. The Dirac cones at the (M) over bar points are anisotropic with large out-of-plane component. TlBiS2 shows normal, topological, and topological crystalline insulator phases under hydrostatic pressure, thus being the first compound to exhibit a phase transition from a topological to a topological crystalline insulator.

  17. Emergence of topological and topological crystalline phases in TlBiS2 and TlSbS2

    KAUST Repository

    Zhang, Qingyun; Cheng, Yingchun; Schwingenschlö gl, Udo

    2015-01-01

    Using first-principles calculations, we investigate the band structure evolution and topological phase transitions in TlBiS2 and TlSbS2 under hydrostatic pressure as well as uniaxial and biaxial strain. The phase transitions are identified by parity analysis and by calculating the surface states. Zero, one, and four Dirac cones are found for the (111) surfaces of both TlBiS2 and TlSbS2 when the pressure grows, which confirms trivial-nontrivial-trivial phase transitions. The Dirac cones at the (M) over bar points are anisotropic with large out-of-plane component. TlBiS2 shows normal, topological, and topological crystalline insulator phases under hydrostatic pressure, thus being the first compound to exhibit a phase transition from a topological to a topological crystalline insulator.

  18. First-principles approach to the dynamic magnetoelectric couplings for the non-reciprocal directional dichroism in BiFeO3

    Science.gov (United States)

    Lee, Jun Hee; Kézsmáki, István; Fishman, Randy S.

    2016-04-01

    Due to the complicated magnetic and crystallographic structures of BiFeO3, its magnetoelectric (ME) couplings and microscopic model Hamiltonian remain poorly understood. By employing a first-principles approach, we uncover all possible ME couplings associated with the spin-current (SC) and exchange-striction (ES) polarizations, and construct an appropriate Hamiltonian for the long-range spin-cycloid in BiFeO3. First-principles calculations are used to understand the microscopic origins of the ME couplings. We find that inversion symmetries broken by ferroelectric and antiferroelectric distortions induce the SC and the ES polarizations, which cooperatively produce the dynamic ME effects in BiFeO3. A model motivated by first principles reproduces the absorption difference of counter-propagating light beams called non-reciprocal directional dichroism. The current paper focuses on the spin-driven (SD) polarizations produced by a dynamic electric field, i.e. the dynamic ME couplings. Due to the inertial properties of Fe, the dynamic SD polarizations differ significantly from the static SD polarizations. Our systematic approach can be generally applied to any multiferroic material, laying the foundation for revealing hidden ME couplings on the atomic scale and for exploiting optical ME effects in the next generation of technological devices such as optical diodes. This manuscript has been written by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan.

  19. Bi-directional effects of depressed mood in the postnatal period on mother-infant non-verbal engagement with picture books.

    Science.gov (United States)

    Reissland, Nadja; Burt, Mike

    2010-12-01

    The purpose of the present study is to examine the bi-directional nature of maternal depressed mood in the postnatal period on maternal and infant non-verbal behaviors while looking at a picture book. Although, it is acknowledged that non-verbal engagement with picture books in infancy plays an important role, the effect of maternal depressed mood on stimulating the interest of infants in books is not known. Sixty-one mothers and their infants, 38 boys and 23 girls, were observed twice approximately 3 months apart (first observation: mean age 6.8 months, range 3-11 months, 32 mothers with depressed mood; second observation: mean age 10.2 months, range 6-16 months, 17 mothers with depressed mood). There was a significant effect for depressed mood on negative behaviors: infants of mothers with depressed mood tended to push away and close books more often. The frequency of negative behaviors (pushing the book away/closing it on the part of the infant and withholding the book and restraining the infant on the part of the mother) were behaviors which if expressed during the first visit were more likely to be expressed during the second visit. Levels of negative behaviors by mother and infant were strongly related during each visit. Additionally, the pattern between visits suggests that maternal negative behavior may be the cause of her infant negative behavior. These results are discussed in terms of the effects of maternal depressed mood on the bi-directional relation of non-verbal engagement of mother and child. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.

  20. A Hierarchical multi-input and output Bi-GRU Model for Sentiment Analysis on Customer Reviews

    Science.gov (United States)

    Zhang, Liujie; Zhou, Yanquan; Duan, Xiuyu; Chen, Ruiqi

    2018-03-01

    Multi-label sentiment classification on customer reviews is a practical challenging task in Natural Language Processing. In this paper, we propose a hierarchical multi-input and output model based bi-directional recurrent neural network, which both considers the semantic and lexical information of emotional expression. Our model applies two independent Bi-GRU layer to generate part of speech and sentence representation. Then the lexical information is considered via attention over output of softmax activation on part of speech representation. In addition, we combine probability of auxiliary labels as feature with hidden layer to capturing crucial correlation between output labels. The experimental result shows that our model is computationally efficient and achieves breakthrough improvements on customer reviews dataset.

  1. Physical activity and self-esteem: testing direct and indirect relationships associated with psychological and physical mechanisms.

    Science.gov (United States)

    Zamani Sani, Seyed Hojjat; Fathirezaie, Zahra; Brand, Serge; Pühse, Uwe; Holsboer-Trachsler, Edith; Gerber, Markus; Talepasand, Siavash

    2016-01-01

    In the present study, we investigated the relationship between physical activity (PA) and self-esteem (SE), while introducing body mass index (BMI), perceived physical fitness (PPF), and body image (BI) in adults (N =264, M =38.10 years). The findings indicated that PA was directly and indirectly associated with SE. BMI predicted SE neither directly nor indirectly, but was directly associated with PPF and both directly and indirectly with BI. Furthermore, PPF was directly related to BI and SE, and a direct association was found between BI and SE. The pattern of results suggests that among a sample of adults, PA is directly and indirectly associated with SE, PPF, and BI, but not with BMI. PA, PPF, and BI appear to play an important role in SE. Accordingly, regular PA should be promoted, in particular, among adults reporting lower SE.

  2. Synthesis and temperature dependent Raman studies of large crystalline faces topological GeBi4Te7 single crystal

    Science.gov (United States)

    Mal, Priyanath; Bera, G.; Turpu, G. R.; Srivastava, Sunil K.; Das, Pradip

    2018-05-01

    We present a study of structural and vibrational properties of topological insulator GeBi4Te7. Modified Bridgeman technique is employed to synthesize the single crystal with relatively large crystalline faces. Sharp (0 0 l) reflection confirms the high crystallinity of the single crystal. We have performed temperature dependent Raman measurement for both parallel and perpendicular to crystallographic c axis geometry. In parallel configuration we have observed seven Raman modes whereas in perpendicular geometry only four of these are identified. Appearance and disappearance of Raman modes having different intensities for parallel and perpendicular to c measurement attribute to the mode polarization. Progressive blue shift is observed with lowering temperature, reflects the increase in internal stress.

  3. Electronic structure of the BiSI cluster

    Energy Technology Data Exchange (ETDEWEB)

    Audzijonis, A. [Department of Physics, Vilnius Pedagogical University, Studentu 39, LT-08106 Vilnius (Lithuania); Gaigalas, G. [Department of Physics, Vilnius Pedagogical University, Studentu 39, LT-08106 Vilnius (Lithuania); Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, LT-01108 Vilnius (Lithuania); Zigas, L. [Department of Physics, Vilnius Pedagogical University, Studentu 39, LT-08106 Vilnius (Lithuania)]. E-mail: kkol@vpu.lt; Pauliukas, A. [Department of Physics, Vilnius Pedagogical University, Studentu 39, LT-08106 Vilnius (Lithuania); Zaltauskas, R. [Department of Physics, Vilnius Pedagogical University, Studentu 39, LT-08106 Vilnius (Lithuania); Cerskus, A. [Department of Physics, Vilnius Pedagogical University, Studentu 39, LT-08106 Vilnius (Lithuania); Narusis, J. [Department of Physics, Vilnius Pedagogical University, Studentu 39, LT-08106 Vilnius (Lithuania); Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, LT-01108 Vilnius (Lithuania); Kvedaravicius, A. [Department of Physics, Vilnius Pedagogical University, Studentu 39, LT-08106 Vilnius (Lithuania)

    2007-03-15

    The energy levels of valence bands (VB) and core levels (CL) of the BiSI crystals have been investigated theoretically. The molecular model of this crystal was used for calculation of VB and CL by the unrestricted Hartree-Fock method using GAMESS program, with Hw and MINI basis set. The molecular cluster consisting of 20 molecules of BiSI was used for calculations of averaged total density of states including atom vibrations. The spectra of averaged total density of states from VB of BiSI cluster has been compared with experimental X-ray photoelectron spectra (XPS) of VB of SbSI crystal. The results clarify that the atomic vibrations is one of possible reasons for the smoother appearance of the experimental XPS. The investigation of vibrational spectrum reveals new experimental information about the reflection spectrum of BiSI crystals. The cluster model calculations have shown that the splitting of the CL in the BiSI may be caused by the photoelectron emission from the atoms at the surface that is in different valence states. The cluster model calculation showed that splitting energy of CL depends on difference of ionic charges of the same atoms at the edges of BiSI cluster.

  4. Electronic structure of the BiSI cluster

    International Nuclear Information System (INIS)

    Audzijonis, A.; Gaigalas, G.; Zigas, L.; Pauliukas, A.; Zaltauskas, R.; Cerskus, A.; Narusis, J.; Kvedaravicius, A.

    2007-01-01

    The energy levels of valence bands (VB) and core levels (CL) of the BiSI crystals have been investigated theoretically. The molecular model of this crystal was used for calculation of VB and CL by the unrestricted Hartree-Fock method using GAMESS program, with Hw and MINI basis set. The molecular cluster consisting of 20 molecules of BiSI was used for calculations of averaged total density of states including atom vibrations. The spectra of averaged total density of states from VB of BiSI cluster has been compared with experimental X-ray photoelectron spectra (XPS) of VB of SbSI crystal. The results clarify that the atomic vibrations is one of possible reasons for the smoother appearance of the experimental XPS. The investigation of vibrational spectrum reveals new experimental information about the reflection spectrum of BiSI crystals. The cluster model calculations have shown that the splitting of the CL in the BiSI may be caused by the photoelectron emission from the atoms at the surface that is in different valence states. The cluster model calculation showed that splitting energy of CL depends on difference of ionic charges of the same atoms at the edges of BiSI cluster

  5. Accuracy and Transferability of Ab Initio Electronic Band Structure Calculations for Doped BiFeO3

    Science.gov (United States)

    Gebhardt, Julian; Rappe, Andrew M.

    2017-11-01

    BiFeO3 is a multiferroic material and, therefore, highly interesting with respect to future oxide electronics. In order to realize such devices, pn junctions need to be fabricated, which are currently impeded by the lack of successful p-type doping in this material. In order to guide the numerous research efforts in this field, we recently finished a comprehensive computational study, investigating the influence of many dopants onto the electronic structure of BiFeO3. In order to allow for this large scale ab initio study, the computational setup had to be accurate and efficient. Here we discuss the details of this assessment, showing that standard density-functional theory (DFT) yields good structural properties. The obtained electronic structure, however, suffers from well-known shortcomings. By comparing the conventional DFT results for alkali and alkaline-earth metal doping with more accurate hybrid-DFT calculations, we show that, in this case, the problems of standard DFT go beyond a simple systematic error. Conventional DFT shows bad transferability and the more reliable hybrid-DFT has to be chosen for a qualitatively correct prediction of doping induced changes in the electronic structure of BiFeO3.

  6. Magnetic properties in MnBi alloy of small crystallites for permanent magnet devices

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, S. K.; Prakash, H. R.; Ram, S., E-mail: jms.sanjeev@gmail.com [Materials Science Centre, Indian Institute of Technology, Kharagpur-721302 (India)

    2016-05-06

    A rare-earth free alloy like MnBi is a potential candidate for developing small magnets and devices. In a commercially viable method, a MnBi alloy was prepared by arc melting Mn and Bi metals in a 1:1 ratio. In terms of the X-ray diffraction a single crystalline MnBi phase is formed of the as prepared alloy. FESEM images delineate thin MnBi layers (25 – 40 nm thickness) of average EDX composition throughout the specimen. A large coercivity 5.501 kOe (6.5 emu/g magnetization) observed in an M-H at 300 K is decreased to 0.171 (9.0 emu/g magnetization) at 100 K in decreasing upon cooling.

  7. Effects of Bi Addition on the Microstructure and Mechanical Properties of Nanocrystalline Ag Coatings

    Directory of Open Access Journals (Sweden)

    Yuxin Wang

    2017-08-01

    Full Text Available In this study we investigated the effects of Bi addition on the microstructure and mechanical properties of an electrodeposited nanocrystalline Ag coating. Microstructural features were investigated with transmission electron microscopy (TEM. The results indicate that the addition of Bi introduced nanometer-scale Ag-Bi solid solution particles and more internal defects to the initial Ag microstructures. The anisotropic elastic-plastic properties of the Ag nanocrystalline coating with and without Bi addition were examined with nanoindentation experiments in conjunction with the recently-developed inverse method. The results indicate that the as-deposited nanocrystalline Ag coating contained high mechanical anisotropy. With the addition of 1 atomic percent (at% Bi, the anisotropy within Ag-Bi coating was very small, and yield strength of the nanocrystalline Ag-Bi alloy in both longitudinal and transverse directions were improved by over 100% compared to that of Ag. On the other hand, the strain-hardening exponent of Ag-Bi was reduced to 0.055 from the original 0.16 of the Ag coating. Furthermore, the addition of Bi only slightly increased the electrical resistivity of the Ag-Bi coating in comparison to Ag. Results of our study indicate that Bi addition is a promising method for improving the mechanical and physical performances of Ag coating for electrical contacts.

  8. Polycrystalline and Mesoporous 3-D Bi2O3 Nanostructured Negatrodes for High-Energy and Power-Asymmetric Supercapacitors: Superfast Room-Temperature Direct Wet Chemical Growth.

    Science.gov (United States)

    Shinde, Nanasaheb M; Xia, Qi Xun; Yun, Je Moon; Mane, Rajaram S; Kim, Kwang Ho

    2018-04-04

    Superfast (≤10 min) room-temperature (300 K) chemical synthesis of three-dimensional (3-D) polycrystalline and mesoporous bismuth(III) oxide (Bi 2 O 3 ) nanostructured negatrode (as an abbreviation of negative electrode) materials, viz., coconut shell, marigold, honey nest cross section and rose with different surface areas, charge transfer resistances, and electrochemical performances essential for energy storage, harvesting, and even catalysis devices, are directly grown onto Ni foam without and with poly(ethylene glycol), ethylene glycol, and ammonium fluoride surfactants, respectively. Smaller diffusion lengths, caused by the involvement of irregular crevices, allow electrolyte ions to infiltrate deeply, increasing the utility of inner active sites for the following electrochemical performance. A marigold 3-D Bi 2 O 3 electrode of 58 m 2 ·g -1 surface area has demonstrated a specific capacitance of 447 F·g -1 at 2 A·g -1 and chemical stability of 85% even after 5000 redox cycles at 10 A·g -1 in a 6 M KOH electrolyte solution, which were higher than those of other morphology negatrode materials. An asymmetric supercapacitor (AS) device assembled with marigold Bi 2 O 3 negatrode and manganese(II) carbonate quantum dots/nickel hydrogen-manganese(II)-carbonate (MnCO 3 QDs/NiH-Mn-CO 3 ) positrode corroborates as high as 51 Wh·kg -1 energy at 1500 W·kg -1 power and nearly 81% cycling stability even after 5000 cycles. The obtained results were comparable or superior to the values reported previously for other Bi 2 O 3 morphologies. This AS assembly glowed a red-light-emitting diode for 20 min, demonstrating the scientific and industrial credentials of the developed superfast Bi 2 O 3 nanostructured negatrodes in assembling various energy storage devices.

  9. Prevention of intra-abdominal adhesion by bi-layer electrospun membrane.

    Science.gov (United States)

    Jiang, Shichao; Wang, Wei; Yan, Hede; Fan, Cunyi

    2013-06-04

    The aim of this study was to compare the anti-adhesion efficacy of a bi-layer electrospun fibrous membrane consisting of hyaluronic acid-loaded poly(ε-caprolactone) (PCL) fibrous membrane as the inner layer and PCL fibrous membrane as the outer layer with a single-layer PCL electrospun fibrous membrane in a rat cecum abrasion model. The rat model utilized a cecal abrasion and abdominal wall insult surgical protocol. The bi-layer and PCL membranes were applied between the cecum and the abdominal wall, respectively. Control animals did not receive any treatment. After postoperative day 14, a visual semiquantitative grading scale was used to grade the extent of adhesion. Histological analysis was performed to reveal the features of adhesion tissues. Bi-layer membrane treated animals showed significantly lower adhesion scores than control animals (p compared with the PCL membrane. Histological analysis of the bi-layer membrane treated rat rarely demonstrated tissue adhesion while that of the PCL membrane treated rat and control rat showed loose and dense adhesion tissues, respectively. Bi-layer membrane can efficiently prevent adhesion formation in abdominal cavity and showed a significantly decreased adhesion tissue formation compared with the control.

  10. Phase development and kinetics of high temperature Bi-2223 phase

    International Nuclear Information System (INIS)

    Yavuz, M.; Maeda, H.; Hua, K.L.; Shi, X.D.

    1998-01-01

    The two-dimensional nucleation (random)-growth mechanism were observed as a support for the related previous works, which is attributable to the growth of the Bi-2223 grain in the a-b plane direction of the Bi-2212 matrix is being much faster than in the c-direction, or that the early-formed plate-like 2212 phase confines the 2223 product. At the beginning of the reaction, the additional phases are partially melted. Because of the structure, composition and thermal fluctuation, the 2223 nucleates and grows in the phase boundary between the liquid phase and Bi-2212. It was shown here that the nucleation and the growth rate were relatively fast between 0 and 36 h. At the final stage, between 36 and 60 h, because of the impingement of the growth fronts of different nuclei, the high formation rate of 2223 is suppressed. The major reactant 2212 remains as a solid and its plate-like configuration determines the two dimensional nature of the reaction. The amount of liquid forms during reaction is small. (orig.)

  11. An unexpected role for the yeast nucleotide exchange factor Sil1 as a reductant acting on the molecular chaperone BiP

    Science.gov (United States)

    Siegenthaler, Kevin D; Pareja, Kristeen A; Wang, Jie; Sevier, Carolyn S

    2017-01-01

    Unfavorable redox conditions in the endoplasmic reticulum (ER) can decrease the capacity for protein secretion, altering vital cell functions. While systems to manage reductive stress are well-established, how cells cope with an overly oxidizing ER remains largely undefined. In previous work (Wang et al., 2014), we demonstrated that the chaperone BiP is a sensor of overly oxidizing ER conditions. We showed that modification of a conserved BiP cysteine during stress beneficially alters BiP chaperone activity to cope with suboptimal folding conditions. How this cysteine is reduced to reestablish 'normal' BiP activity post-oxidative stress has remained unknown. Here we demonstrate that BiP's nucleotide exchange factor – Sil1 – can reverse BiP cysteine oxidation. This previously unexpected reductant capacity for yeast Sil1 has potential implications for the human ataxia Marinesco-Sjögren syndrome, where it is interesting to speculate that a disruption in ER redox-signaling (due to genetic defects in SIL1) may influence disease pathology. DOI: http://dx.doi.org/10.7554/eLife.24141.001 PMID:28257000

  12. A comparative study of the Aurivillius phase ferroelectrics CaBi 4Ti 4O 15 and BaBi 4Ti 4O 15

    Science.gov (United States)

    Tellier, J.; Boullay, Ph.; Manier, M.; Mercurio, D.

    2004-06-01

    The room temperature structures of the four-layer Aurivillius phase ferroelectrics CaBi 4Ti 4O 15 and BaBi 4Ti 4O 15 are determined by means of single crystal X-ray diffraction. Regarding the CaBi 4Ti 4O 15 phase, in agreement with the tolerance factor, a significant deformation of the perovskite blocks is observed. The rotation system of the octahedra is typical from even layer Aurivillius phases and leads to the use of the space group A2 1am. For the BaBi 4Ti 4O 15 phase, only a weak variation with respect to the F2 mm space group can be suggested from single crystal X-ray diffraction. A significant presence of Ba atoms in the [ M2O 2] slabs is confirmed in agreement with the previous works but specific Ba 2+ and Bi 3+ sites have to be considered due to the large difference in bounding requirement of these cations. Possible origins for the ferroelectric relaxor behavior of the Ba-based compound are discussed in view of the presented structural analyses.

  13. Morphology effect on photocatalytic activity in Bi3Fe0.5Nb1.5O9

    Science.gov (United States)

    Yin, Xiaofeng; Li, Xiaoning; Gu, Wen; Zou, Wei; Liu, Huan; Zhu, Liuyang; Fu, Zhengping; Lu, Yalin

    2018-06-01

    In this work, the Aurivillius-phase ferroelectric Bi3Fe0.5Nb1.5O9 were synthesized by hydrothermal (BFNO-H) and solid state methods (BFNO-S), respectively. The BFNO-H shows a hierarchical morphology, which is stacked by intersecting single-crystal nanosheets with {001} and {110} exposed facets, while the BFNO-S shows disorganized micron-scale morphology. BFNO-H shows a much stronger photodegradation activity (10.4 times and 9.8 times) than BFNO-S in the visible-light photodegradation of rhodamine B (RhB) and salicylic acid. The higher photodegradation activity of BFNO-H was firstly ascribed to the hierarchical structure and the larger specific surface area (16.586 m2 g‑1) because a large specific surface area can increase reactive sites and shorten photogenerated carrier migration distance. However, after being normalized by the specific surface area, BFNO-H still performs better than BFNO-S, implying that the specific surface area is not the only factor that determines the photocatalytic activity. Considering that the built-in electric field originating from spontaneous polarization in Bi3Fe0.5Nb1.5O9 has existed in both ab plane and c direction, it matches well with the {001} and {110} exposed facets of BFNO-H nanosheets. This appropriate matching in BFNO-H nanosheets may improve the separation and transmission of photogenerated electron–hole pairs and further enhance its photocatalytic activity. Moreover, the trapping experiments reveals that holes (h +) are the main active species and hole-derived oxidation is the main redox reaction during photodegradation of organic pollutions.

  14. Solidification of Bi2Sr2Ca1Cu2Oy and Bi2Sr1.75Ca0.25CuOy

    International Nuclear Information System (INIS)

    Holesinger, T.G.; Miller, D.J.; Viswanathan, H.K.; Chumbley, L.S.

    1993-01-01

    The solidification processes for the compositions Bi 2 Sr 2 CaCu 2 O y (2212) and Bi 2 Sr 1.75 Ca 0.25 CuO y (2201) were determined as a function of oxygen partial pressure. During solidification in argon, the superconducting phases were generally not observed to form for either composition. In both cases, the solidus is lowered to approximately 750 degree C. Solidification of Bi 2 Sr 1.75 Ca 0.25 CuO y in Ar resulted in a divorced eutectic structure of Bi 2 Sr 2-x Ca x O y (22x) and Cu 2 O while solidification of Bi 2 Sr 2 CaCu 2 O y in Ar resulted in a divorced eutectic structure of Bi 2 Sr 3-x Ca x O y (23x) and Cu 2 O. Solidification of Bi 2 Sr 1.75 Ca 0.25 CuO y in O 2 resulted in large grains of 2201 interspersed with small regions containing the eutectic structure of 22x and CuO/Cu 2 O. Solidification of Bi 2 Sr 2 CaCu 2 O y in partial pressures of 1%, 20%, and 100% oxygen resulted in multiphase samples consisting of 2212, 2201, some alkaline-earth cuprates, and both divorced eutectic structures found during solidification in Ar. For both compositions, these latter structures can be attributed to oxygen deficiencies present in the melt regardless of the overpressure of oxygen. These eutectic structures are unstable and convert into the superconducting phases during subsequent anneals in oxygen. The formation process of the 2212 phase during solidification from the melt was determined to proceed through an intermediate state involving the 2201 phase

  15. Global EiBI-monopole

    Directory of Open Access Journals (Sweden)

    JIN Xinghua

    2014-04-01

    Full Text Available A global EiBI-monopole problem is studied under EiBI gravitational theory.The equations of global EiBI-monopole are derived in the curved spacetime and the relation between the spacetime metric and auxiliary metric is found.In the case of a very small parameter,an asymptotic form of equations is given.The series solutions of global EiBI-monopole at infinity are found.

  16. Bi-layer plate-type acoustic metamaterials with Willis coupling

    Science.gov (United States)

    Ma, Fuyin; Huang, Meng; Xu, Yicai; Wu, Jiu Hui

    2018-01-01

    Dynamic effective negative parameters are principal to the representation of the physical properties of metamaterials. In this paper, a bi-layer plate-type unit was proposed with both a negative mass density and a negative bulk modulus; moreover, through analysis of these bi-layer structures, some important problems about acoustic metamaterials were studied. First, dynamic effective mass densities and the bulk modulus of the bi-layer plate-type acoustic structure were clarified through both the direct and the retrieval methods, and, in addition, the intrinsic relationship between the sound transmission (absorption) characteristics and the effective parameters was analyzed. Furthermore, the properties of dynamic effective parameters for an asymmetric bi-layer acoustic structure were further considered through an analysis of experimental data, and the modified effective parameters were then obtained through consideration of the Willis coupling in the asymmetric passive system. In addition, by taking both the clamped and the periodic boundary conditions into consideration in the bi-layer plate-type acoustic system, new perspectives were presented for study on the effective parameters and sound insulation properties in the range below the cut-off frequency. The special acoustic properties established by these effective parameters could enrich our knowledge and provide guidance for the design and installation of acoustic metamaterial structures in future sound engineering practice.

  17. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Loganathan, Muthukumaran; Bristow, Douglas A., E-mail: dbristow@mst.edu [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, Missouri 65401 (United States)

    2014-04-15

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.

  18. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy.

    Science.gov (United States)

    Loganathan, Muthukumaran; Bristow, Douglas A

    2014-04-01

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.

  19. Seven fundamental, unsolved questions in molecular biology. Cooperative storage and bi-directional transfer of biological information by nucleic acids and proteins: an alternative to "central dogma".

    Science.gov (United States)

    Biro, J C

    2004-01-01

    The Human Genome Mapping Project provided us a large amount of sequence data. However our understanding of these data did not grow proportionally, because old dogmas still set the limits of our thinking. The gene-centric, reductionistical side of molecular biology is reviewed and seven problems are formulated, each indicating the insufficiency of the "central dogma". The following is concluded and suggested: 1. Genes are located and expressed on both DNA strands; 2. Introns are the source of important biological regulation and diversity; 3. Repeats are the frame of the chromatin structure and participate in the chromatin regulation; 4. The molecular accessibility of the canonical dsDNA structure is poor; 5. The genetic code is co-evolved with the amino acids and there is a stereochemical matching between the codes andamino acids; 6. The flow of information between nucleic acids and proteins is bi-directional and reverse translation might exist; 7. Complex genetic information is always carried and stored by nucleic acids and proteins together.

  20. Synthesis, Characterization and Antibacterial Activity of BiVO4 Microstructure

    Science.gov (United States)

    Ekthammathat, Nuengruethai; Phuruangrat, Anukorn; Thongtem, Somchai; Thongtem, Titipun

    2018-05-01

    Hyperbranched BiVO4 microstructure were successfully synthesized by a hydrothermal method. Upon characterization the products by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, selected area electron diffraction (SAED) and photoluminescence (PL) spectroscopy, pure monoclinic hyperbranched BiVO4 with dominant vibration peak at 810 cm-1 and strong photoemission peak at 360 nm was synthesized in the solution with pH 1. In the solution with pH 2, tetragonal BiVO4 phase was also detected. In this research, antibacterial activity against S. aureus and E. coli was investigated by counting the colony forming unit (CFU). At 37°C within 24 h, the monoclinic BiVO4 phase can play the role in inhibiting S. aureus growth (350 CFU/mL remaining bacteria) better than that against E. coli (a large number of remaining bacteria).

  1. Large-Scale Direct-Writing of Aligned Nanofibers for Flexible Electronics.

    Science.gov (United States)

    Ye, Dong; Ding, Yajiang; Duan, Yongqing; Su, Jiangtao; Yin, Zhouping; Huang, Yong An

    2018-05-01

    Nanofibers/nanowires usually exhibit exceptionally low flexural rigidities and remarkable tolerance against mechanical bending, showing superior advantages in flexible electronics applications. Electrospinning is regarded as a powerful process for this 1D nanostructure; however, it can only be able to produce chaotic fibers that are incompatible with the well-patterned microstructures in flexible electronics. Electro-hydrodynamic (EHD) direct-writing technology enables large-scale deposition of highly aligned nanofibers in an additive, noncontact, real-time adjustment, and individual control manner on rigid or flexible, planar or curved substrates, making it rather attractive in the fabrication of flexible electronics. In this Review, the ground-breaking research progress in the field of EHD direct-writing technology is summarized, including a brief chronology of EHD direct-writing techniques, basic principles and alignment strategies, and applications in flexible electronics. Finally, future prospects are suggested to advance flexible electronics based on orderly arranged EHD direct-written fibers. This technology overcomes the limitations of the resolution of fabrication and viscosity of ink of conventional inkjet printing, and represents major advances in manufacturing of flexible electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Structure and phase transition of BiFeO3 cubic micro-particles prepared by hydrothermal method

    International Nuclear Information System (INIS)

    Zhou, Jian-Ping; Yang, Ruo-Lin; Xiao, Rui-Juan; Chen, Xiao-Ming; Deng, Chao-Yong

    2012-01-01

    Graphical abstract: Bismuth ferrite (BiFeO 3 ) cubic micro-particles with smooth surfaces were synthesized. BiFeO 3 has a hexagonal perovskite structure with a space group R3c below 370 °C and rhombohedral perovskite structure with a space group R3m below 755 °C, undergoes a phase transition in the temperature range of 755–817 °C to a cubic structure, then decompose to liquid and Fe 2 O 3 above 939 °C. Highlights: ► BiFeO 3 micro-particles with smooth surface were synthesized by hydrothermal method. ► BiFeO 3 enjoys hexagonal structure with well element ratio and chemical valence. ► BiFeO 3 transition from rhombohedral phase to cubic phase lasts 60 °C. -- Abstract: Single-phase bismuth ferrite (BiFeO 3 ) powders were synthesized with a hydrothermal method by controlling the experimental conditions carefully. The powder structure, morphology and composition were characterized by using X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscope, Raman measurement and X-ray photoelectron spectroscopy. The particles change from irregular agglomerations to regular cubes with increasing KOH concentration. The large BiFeO 3 cubic particles enjoy much smooth surfaces with well-matched element ratio (Bi:Fe:O = 1:1:3) and chemical valence (Bi 3+ , Fe 3+ and O 2− ). The high temperature XRD and differential scanning calorimetry show that BiFeO 3 powders have a hexagonal perovskite structure with a space group R3c below 370 °C and a rhombohedral structure with a space group R3m below 755 °C. BiFeO 3 undergoes a phase transition in the temperature range of 755–817 °C from rhombohedral structure to a cubic phase, then decomposes to liquid and Fe 2 O 3 above 939 °C.

  3. Growth of (100)-highly textured BaBiO{sub 3} thin films on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ferreyra, C. [GIyA and INN, CNEA, Av. Gral Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Departamento de Física, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1, Ciudad Universitaria, Buenos Aires (Argentina); Marchini, F. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Departamento de Química Inorgánica, Analítica y Química-Física, INQUIMAE-CONICET, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, Buenos Aires (Argentina); Granell, P. [INTI, CMNB, Av. Gral Paz 5445, B1650KNA San Martín, Buenos Aires (Argentina); Golmar, F. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); INTI, CMNB, Av. Gral Paz 5445, B1650KNA San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología, UNSAM, Campus Miguelete, 1650 San Martín, Buenos Aires (Argentina); Albornoz, C. [GIyA and INN, CNEA, Av. Gral Paz 1499, 1650 San Martín, Buenos Aires (Argentina); and others

    2016-08-01

    We report on the growth and characterization of non-epitaxial but (100)-highly textured BaBiO{sub 3} thin films on silicon substrates. We have found the deposition conditions that optimize the texture, and show that the textured growth is favoured by the formation of a BaO layer at the first growth stages. X-ray diffraction Φ-scans, together with the observation that the same textured growth is found on films grown on Pt and SiO{sub 2} buffered Si, demonstrate the absence of epitaxy. Finally, we have shown that our (100)-oriented BaBiO{sub 3} films can be used as suitable buffers for the growth of textured heterostructures on silicon, which could facilitate the integration of potential devices with standard electronics. - Highlights: • BaBiO{sub 3} thin films were grown on Si substrates and characterized. • Films prepared using optimized conditions are highly textured in the (100) direction. • The absence of in-plane texture was demonstrated by X-ray diffraction. • Our films are suitable buffers for the growth of (100)-textured oxide heterostructures.

  4. Aurivillius-Popper mixed superconductors in BiO--CuO--(Sr/sub 0.5/, Ca/sub 0.5/)O system

    International Nuclear Information System (INIS)

    Fukuhara, M.; Bhalla, A.S.; Mulay, L.N.; Newnham, R.E.

    1989-01-01

    We report the effect of inhomogeneities on the electric resistivity and ac magnetic susceptibility in Aurivillius-like bismuth mixed phase oxides of the BiO--Cuo--(Sr/sub 0.5/, Ca/sub 0.5/)O system and propose a crystal structure of the major phase having highest T/sub c/. Nominal Aurivillius compositions with molar ratios of BiO/(Sr/sub 0.5/, Ca/sub 0.5/)O = 1/2 are superconductors with T/sub c/ ranging from 83 to 107 K, and are accompanied by a large expansion during sintering due to the formation of Kirkendall voids. T/sub c/ increases with decreasing of the c lattice parameter. An oxide BiSrCaCu 2 O/sub x/ (n = 2) shows a maximum T/sub c/ value of 107 K and an onset of superconductivity at a much higher temperature. It seems that the structure of Bi 2 Sr 2 CaCu 2 O/sub x/ consists of an Aurivillius-like phase having two perovskite layers and a Popper mixed phase. The ac magnetic susceptibility showed an overall decrease in susceptibility with time up to 220 days. This appears to be related to the relief of intralattice strain

  5. Live visualization of genomic loci with BiFC-TALE.

    Science.gov (United States)

    Hu, Huan; Zhang, Hongmin; Wang, Sheng; Ding, Miao; An, Hui; Hou, Yingping; Yang, Xiaojing; Wei, Wensheng; Sun, Yujie; Tang, Chao

    2017-01-11

    Tracking the dynamics of genomic loci is important for understanding the mechanisms of fundamental intracellular processes. However, fluorescent labeling and imaging of such loci in live cells have been challenging. One of the major reasons is the low signal-to-background ratio (SBR) of images mainly caused by the background fluorescence from diffuse full-length fluorescent proteins (FPs) in the living nucleus, hampering the application of live cell genomic labeling methods. Here, combining bimolecular fluorescence complementation (BiFC) and transcription activator-like effector (TALE) technologies, we developed a novel method for labeling genomic loci (BiFC-TALE), which largely reduces the background fluorescence level. Using BiFC-TALE, we demonstrated a significantly improved SBR by imaging telomeres and centromeres in living cells in comparison with the methods using full-length FP.

  6. First-principles study on doping and temperature dependence of thermoelectric property of Bi2S3 thermoelectric material

    International Nuclear Information System (INIS)

    Guo, Donglin; Hu, Chenguo; Zhang, Cuiling

    2013-01-01

    Graphical abstract: The direction-induced ZT is found. At ZZ direction and n = 1.47 × 10 19 cm −3 , the ZT can reach maximal value, 0.36, which is three times as much as maximal laboratorial value. This result matches well the analysis of electron effective mass. Highlights: ► Electrical transportations of Bi 2 S 3 depend on the concentration and temperature. ► The direction-induced ZT is found. ► At ZZ direction and n = 1.47 × 10 19 cm −3 , the ZT can reach maximal value, 0.36. ► The maximal ZT value is three times as much as maximal laboratorial value. ► By doping and temperature tuning, Bi 2 S 3 is a promising thermoelectric material. - Abstract: The electronic structure and thermoelectric property of Bi 2 S 3 are investigated. The electron and hole effective mass of Bi 2 S 3 is analyzed in detail, from which we find that the thermoelectric transportation varies in different directions in Bi 2 S 3 crystal. Along ac plane the higher figure of merit (ZT) could be achieved. For n-type doped Bi 2 S 3 , the optimal doping concentration is found in the range of (1.0–5.0) × 10 19 cm −3 , in which the maximal ZT reaches 0.21 at 900 K, but along ZZ direction, the maximal ZT reaches 0.36. These findings provide a new understanding of thermoelectricity-dependent structure factors and improving ZT ways. The donor concentration N increases as T increases at one bar of pressure under a suitable chemical potential μ, but above this chemical potential μ, the donor concentration N keeps a constant

  7. Does it matter which Life Cycle Assessment (LCA) tool you choose? - a comparative assessment of SimaPro and GaBi

    DEFF Research Database (Denmark)

    Herrmann, Ivan Tengbjerg; Moltesen, Andreas

    2015-01-01

    SimaPro and GaBi are the leading software tools used for life cycle assessments. Assessing product systems applying the exact same unit process foundation would be expected to yield comparable result sets with either tool. The software performances are compared based on a random sample of 100 unit...... of these differences are so large that they could influence the conclusions. For some of the 100 unit processes, six elementary flows were inventoried differently in SimaPro and GaBi, with an extreme maximum comparative ratio of 109. The implementation of the impact assessment methodologies shows notable differences...... processes. The research question investigated here is; can there be a difference between SimaPro and GaBi influencing the results and the decisions based on them? In many cases the results are identical between SimaPro and GaBi or nearly so, but in other cases the results reveal differences. Some...

  8. Photovoltaic effect in Bi2TeO5 photorefractive crystal

    International Nuclear Information System (INIS)

    Oliveira, Ivan de; Capovilla, Danilo Augusto; Carvalho, Jesiel F.; Montenegro, Renata; Fabris, Zanine V.; Frejlich, Jaime

    2015-01-01

    We report on the presence of a strong photovoltaic effect on nominally undoped photorefractive Bi 2 TeO 5 crystals and estimated their Glass photovoltaic constant and photovoltaic field for λ = 532 nm illumination. We directly measured the photovoltaic-based photocurrent in this material under λ = 532 nm wavelength laser light illumination and compared its behavior with that of a well known photovoltaic Fe-doped Lithium Niobate crystal. We also show the photovoltaic current to strongly depend on the polarization direction of light. Holographic diffraction efficiency oscillation during recording and the behavior of fringe-locked running holograms in self-stabilized experiments are also demonstrated here as additional indirect proofs of the photovoltaic nature of this material

  9. High photocatalytic performance of BiOI/Bi{sub 2}WO{sub 6} toward toluene and Reactive Brilliant Red

    Energy Technology Data Exchange (ETDEWEB)

    Li Huiquan [School of Chemistry and Chemical Engineering, Fuyang Normal College, Fuyang 236041 (China); Key Laboratory of Mesoscopic Chemistry of MOE, Jiangsu Provincial Key Laboratory of Nanotechnology, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Cui Yumin, E-mail: cuiyumin0908@163.com [School of Chemistry and Chemical Engineering, Fuyang Normal College, Fuyang 236041 (China); Hong Wenshan [School of Chemistry and Chemical Engineering, Fuyang Normal College, Fuyang 236041 (China)

    2013-01-01

    Graphical abstract: When BiOI/Bi{sub 2}WO{sub 6} catalyst was exposed to UV or visible light, the electrons in the valence band of Bi{sub 2}WO{sub 6} would be excited into the conduction band and then injected into the more positive conduction band of BiOI. Therefore, the photoelectrons were generated from Bi{sub 2}WO{sub 6} and transferred across the interface between BiOI and Bi{sub 2}WO{sub 6} to the surface of BiOI, leaving the photogenerated holes in the valence band of Bi{sub 2}WO{sub 6}. In this way, the photoinduced electron-hole pairs were effectively separated. Highlights: Black-Right-Pointing-Pointer BiOI sensitized Bi{sub 2}WO{sub 6} catalysts were successfully prepared by a facile method. Black-Right-Pointing-Pointer The 13.2% BiOI/Bi{sub 2}WO{sub 6} catalyst exhibits higher photoactivities than P25. Black-Right-Pointing-Pointer A possible transfer process of photogenerated carriers was proposed. - Abstract: BiOI sensitized nano-Bi{sub 2}WO{sub 6} photocatalysts with different BiOI contents were successfully synthesized by a facile deposition method at room temperature, and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) spectra, UV-vis diffuse reflection spectroscopy (UV-vis DRS) and Brunauer-Emmett-Teller (BET) surface area measurements. The photocatalytic activity of BiOI/Bi{sub 2}WO{sub 6} was evaluated by the photo-degradation of Reactive Brilliant Red (X-3B) in suspended solution and toluene in gas phase. It has been shown that the BiOI/Bi{sub 2}WO{sub 6} catalysts exhibit a coexistence of both tetragonal BiOI and orthorhombic Bi{sub 2}WO{sub 6} phases. With increasing BiOI content, the absorption intensity of BiOI/Bi{sub 2}WO{sub 6} catalysts increases in the 380-600 nm region and the absorption edge shifts significantly to longer wavelengths as compared to pure Bi{sub 2}WO{sub 6}. The 13.2% BiOI/Bi{sub 2}WO{sub 6} catalyst exhibits

  10. MLED_BI: a new BI Design Approach to Support Multilingualism in Business Intelligence

    Directory of Open Access Journals (Sweden)

    Nedim Dedić

    2017-11-01

    Full Text Available Existing approaches to support Multilingualism (ML in Business Intelligence (BI create problems for business users, present a number of challenges from the technical perspective, and lead to issues with logical dependence in the star schema. In this paper, we propose MLED_BI (Multilingual Enabled Design for Business Intelligence, a novel BI design approach to support the application of ML in BI Environment, which overcomes the issues and problems found with existing approaches. The approach is based on a revision of the data warehouse dimensional modelling approach and treats the Star Schema as a higher level entity. This paper describes MLED_BI and the validation and evaluation approach used.

  11. Redox signaling via the molecular chaperone BiP protects cells against endoplasmic reticulum-derived oxidative stress

    Science.gov (United States)

    Wang, Jie; Pareja, Kristeen A; Kaiser, Chris A; Sevier, Carolyn S

    2014-01-01

    Oxidative protein folding in the endoplasmic reticulum (ER) has emerged as a potentially significant source of cellular reactive oxygen species (ROS). Recent studies suggest that levels of ROS generated as a byproduct of oxidative folding rival those produced by mitochondrial respiration. Mechanisms that protect cells against oxidant accumulation within the ER have begun to be elucidated yet many questions still remain regarding how cells prevent oxidant-induced damage from ER folding events. Here we report a new role for a central well-characterized player in ER homeostasis as a direct sensor of ER redox imbalance. Specifically we show that a conserved cysteine in the lumenal chaperone BiP is susceptible to oxidation by peroxide, and we demonstrate that oxidation of this conserved cysteine disrupts BiP's ATPase cycle. We propose that alteration of BiP activity upon oxidation helps cells cope with disruption to oxidative folding within the ER during oxidative stress. DOI: http://dx.doi.org/10.7554/eLife.03496.001 PMID:25053742

  12. Convenient hydrothermal decomposition process for preparation of nanocrystalline mineral Cu3BiS3 and Pb1-xBi2x/3S

    International Nuclear Information System (INIS)

    Hu Junqing; Deng Bin; Wang Chunrui; Tang Kaibin; Qian Yitai

    2003-01-01

    Mineral nanocrystalline Cu 3 BiS 3 and Pb 1-x Bi 2x/3 S (or Bi 0.22 Pb 0.89 S 1.22 ) have been prepared at low synthetic temperature of 100-150 deg. C by convenient hydrothermal decomposition process. X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectra, and element analysis were used to characterize and measure the samples. The as-prepared Cu 3 BiS 3 sample consisted of whisker-like particles with an average size of 50x10 nm 2 and the Pb 1-x Bi 2x/3 S sample displayed aggregative particles with size in the range of 30-50 nm. Preliminary results showed that the prepared precursors, reaction temperature and time played a role in the formation of the final products. A possible reaction mechanism was also discussed briefly

  13. Large effect of columnar defects on the thermodynamic properties of Bi2Sr2CaCu2O8 single crystals

    Science.gov (United States)

    van der Beek, C. J.; Konczykowski, M.; Li, T. W.; Kes, P. H.; Benoit, W.

    1996-07-01

    The introduction of columnar defects by irradiation with 5.8-GeV Pb ions is shown to affect significantly the reversible magnetic properties of Bi2Sr2CaCu2O8+δ single crystals. Notably, the suppression of superconducting fluctuations on length scales greater than the separation between columns leads to the disappearance of the ``crossing point'' in the critical fluctuation regime. At lower temperatures, the strong modification of the vortex energy due to pinning leads to an important change of the reversible magnetization. The analysis of the latter permits the direct determination of the pinning energy.

  14. The Quantum Chemistry Calculation and Thermoelectrics of Bi-Sb-Te Series

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The density function theory and discrete variation method(DFT-DVM) was used to study correlation between composition, structure, chemical bond,and property of thermoelectrics of Bi-Sb-Te series.8 models of Bi20-xSbxTe32(x=0,2,6,8,12,14,18 and 20) were calculated.The results show that there is less difference in the ionic bonds between Te(Ⅰ)-Bi(Sb) and Te(Ⅱ)-Bi(Sb), but the covalent bond of Te(Ⅰ)-Bi(Sb) is stronger than that of Te(Ⅱ)-Bi(Sb).The interaction between Te(Ⅰ) and Te(Ⅰ) in different layers is the weakest and the interaction should be Van Der Waals power.The charge of Sb is lower than that of Bi,and the ionic bond of Te-Sb is weaker than that of Te-Bi.The covalent bond of Te-Sb is also weaker than that of Te-Bi.Therefore,the thermoelectric property may be improved by adjusting the electrical conductivity and thermal conductivity through changing the composition in the compounds of Bi-Sb-Te. The calculated results are consistent with the experiments.

  15. Facile large scale synthesis of Bi{sub 2}S{sub 3} nano rods–graphene composite for photocatalytic photoelectrochemical and supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Vadivel, S. [Electrochemical Engineering Laboratory, Department of Chemical Engineering, C. Tech Campus, Anna University, Chennai-600 025 (India); Naveen, A. Nirmalesh [Department of Physics, Anna University, Chennai, Tamil Nadu 600025 (India); Kamalakannan, V.P. [Electrochemical Engineering Laboratory, Department of Chemical Engineering, C. Tech Campus, Anna University, Chennai-600 025 (India); Cao, P. [Department of Chemistry and Materials Engineering, The University of Auckland, PB 92019, Auckland 1142 (New Zealand); Balasubramanian, N., E-mail: nbsbala@annauniv.edu [Electrochemical Engineering Laboratory, Department of Chemical Engineering, C. Tech Campus, Anna University, Chennai-600 025 (India)

    2015-10-01

    Graphical abstract: - Highlights: • A Bi{sub 2}S{sub 3}/RGO composite was synthesized by one pot precipitation method. • The synthesized Bi{sub 2}S{sub 3}/RGO composite exhibit rod like morphology. • As synthesized composite was applied for malachite green degradation. • The synthesized Bi{sub 2}S{sub 3}/RGO composite exhibits a specific capacitance of 290 F g{sup −1} at a scan rate of 1 A g{sup −1}. • Photocatalytic and supercapacitor properties of Bi{sub 2}S{sub 3} were enhanced mainly due to effective graphene incorporation. - Abstract: Bi{sub 2}S{sub 3} nano rods–graphene (BG) composite material was synthesized by a simple one step precipitation method. The crystallanity, structural and morphological properties were studied by the X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy techniques. The photocatalytic activity of BG was evaluated by the photocatalytic degradation of malachite green dye (MG) aqueous solution under the visible light irradiation. The effect of graphene content on the photoelectrochemical property of Bi{sub 2}S{sub 3} nano rods was also studied. The enhancement of photocurrent and photocatalytic properties of BG composite attributed to the synergistic effect between the Bi{sub 2}S{sub 3} nano rods and graphene sheets which improves the charge separation efficiency in Bi{sub 2}S{sub 3} nano rods. The supercapacitor behavior was studied using cyclic voltametry and galvanostatic charge discharge studies. The BG composite exhibits a maximum specific capacitance of 290 F g{sup −1} at a current density of 1 A g{sup −1}. The present study may provide as a new approach in improving the performance of BG composite in supercapacitor, solar cells and photocatalytic applications.

  16. Radio frequency response of Ag-sheathed (Bi, Pb)2Sr2Ca2Cu3O10+x superconducting tapes

    International Nuclear Information System (INIS)

    Grasso, G.

    2000-01-01

    The response of long (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10 conductors fabricated by the oxide-powder-in-tube method to a radio frequency excitation was investigated while employed as the inductive part of large L-C resonating circuits. After removal of the outer silver sheath, superconducting devices cooled down to 77 K showed superior properties compared to equivalent non-superconducting circuits: Bi-based resonators, conceived for a working frequency in the range between 5 and 17 MHz, presented an improvement of the quality factor by a factor of 20. This result opens new perspectives for the application of Bi-based superconducting materials in the detection of a weak radio frequency signal, as in magnetic resonance imaging. (author)

  17. Fabricaion of improved novel p–n junction BiOI/Bi{sub 2}Sn{sub 2}O{sub 7} nanocomposite for visible light driven photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Weicheng [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Jianzhang, E-mail: fangjzh@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China); Zhu, Ximiao [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Zhanqiang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China); Cen, Chaoping [The Key Laboratory of Water and Air Pollution Control of Guangdong Province, South China Institute of Environmental Sciences, Guangzhou 510655 (China)

    2015-12-15

    Graphical abstract: - Highlights: • A p–n heterojunction photocatalyst BiOI/Bi{sub 2}Sn{sub 2}O{sub 7} was prepared by hydrothermal method. • 4% BiOI/Bi{sub 2}Sn{sub 2}O{sub 7} with maximal photocatalytic degradation efficiency (RhB) of 99.9%. • A specific degradation routes of RhB was illustrated. • The photocatalytic mechanism is discussed according to p–n junction principles. • • O{sub 2}{sup −} and h+ are the main reactive species for the degradation of RhB. - Abstract: A series of novel p−n junction photocatalysts BiOI/Bi{sub 2}Sn{sub 2}O{sub 7} (BiOI/BSO) were successfully fabricated via a facile hydrothermal method. The phase structures, morphologies and optical properties of the as-prepared samples were studied by XRD, TEM, HRTEM, BET, XPS, UV–vis DRS and photoluminescence (PL) spectroscopy. The results showed that BiOI/BSO heteronanostructures displayed much higher photocatalytic activity than pure BSO and BiOI for the degradation of rhodamine B (RhB). The best photocatalytic activity of BiOI/BSO with almost 99.9% RhB degradation situated at molar percentage ratio of 4% after 6 h irradiation. The enhanced photocatalytic performance of BiOI/BSO could be mainly attributed to the formation of the heterojunction between p-BiOI and n-BSO, which effectively restrains the recombination of photoinduced electron–hole pairs. Moreover, the study of radical scavengers affirmed that h{sup +} and • O{sub 2}{sup −} were the primary reactive species for the degradation of RhB.

  18. Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

    International Nuclear Information System (INIS)

    Xiong Ka; Wang Weichao; Alshareef, Husam N; Gupta, Rahul P; Gnade, Bruce E; Cho, Kyeongjae; White, John B

    2010-01-01

    We investigate the electronic structures and stability for Ni/Bi 2 Te 3 , NiTe/Bi 2 Te 3 , Co/Bi 2 Te 3 and CoTe 2 /Bi 2 Te 3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi 2 Te 3 . The interface formation energy for Co/Bi 2 Te 3 interfaces is much lower than that of Ni/Bi 2 Te 3 interfaces. Furthermore, we found that NiTe on Bi 2 Te 3 is more stable than Ni, while the formation energies for Co and CoTe 2 on Bi 2 Te 3 are comparable.

  19. Bi sub 2 Sr sub 2 Ca sub n sub - sub 1 Cu sub n O sub y films sputtered on substrates of Bi sub 2 Sr sub 2 CuO sub y single crystals

    CERN Document Server

    Katsurahara, K; Matsumoto, K; Fujiwara, N; Tanaka, H; Kishida, S

    2003-01-01

    We prepared Bi sub 2 Sr sub 2 CaCu sub 2 O sub y (Bi-2212) films on substrates of Bi sub 2 Sr sub 2 CuO sub y (Bi-2201) single crystals by a rf magnetron sputtering method, where He and O sub 2 mixture sputtering gas and an off-axis geometry were used. The EPMA measurement indicated that the films deposited on the Bi-2201 single crystal had approximately the same composition as those on MgO substrate, which showed a Bi-221 single-phase. The film deposited on the Bi-2201 single crystal post-annealed at 500degC for 0.5h showed a metallic temperature dependent resistance in the normal state and the superconducting transition (T sub c sup o sup n sup s sup e sup t) of about 80 K. Therefore, the Bi-2212 films are considerate to grow on the substrate of the Bi-2201 singe crystal. (author)

  20. Performance Analysis of Video PHY Controller Using Unidirection and Bi-directional IO Standard via 7 Series FPGA

    DEFF Research Database (Denmark)

    Das, Bhagwan; Abdullah, M F L; Hussain, Dil muhammed Akbar

    2017-01-01

    graphics consumes more power, this creates a need of designing the low power design for Video PHY controller. In this paper, the performance of Video PHY controller is analyzed by comparing the power consumption of unidirectional and bi-directional IO Standard over 7 series FPGA. It is determined...... that total on-chip power is reduced for unidirectional IO Standard based Video PHY controller compared to bidirectional IO Standard based Video PHY controller. The most significant achievement of this work is that it is concluded that unidirectional IO Standard based Video PHY controller consume least...... standby power compared to bidirectional IO Standard based Video PHY controller. It is defined that for 6 GHz operated frequency Video PHY controller, the 32% total on-chip power is reduced using unidirectional IO Standard based Video PHY controller is less compared to bidirectional IO Standard based Video...

  1. Unidirectional THz radiation propagation in BiFeO3

    Science.gov (United States)

    Room, Toomas

    The mutual coupling between magnetism and electricity present in many multiferroic materials permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to write a magnetic state current-free by an electric voltage would provide a huge technological advantage. However, ME coupling changes the low energy electrodynamics of these materials in unprecedented way - optical ME effects give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. The transparent direction can be switched with dc magnetic or electric field, thus opening up new possibilities to manipulate the propagation of electromagnetic waves in multiferroic materials. We studied the unidirectional transmission of THz radiation in BiFeO3 crystals, the unique multiferroic compound offering a real potential for room temperature applications. The electrodynamics of BiFeO3 at 1THz and below is dominated by the spin wave modes of cycloidal spin order. We found that the optical magnetoelectric effect generated by spin waves in BiFeO3 is robust enough to cause considerable nonreciprocal directional dichroism in the GHz-THz range even at room temperature. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. Our work demonstrates that the nonreciprocal directional dichroism spectra of low energy excitations and their theoretical analysis provide microscopic model of ME couplings in multiferroic materials. Recent THz spectroscopy studies of multiferroic materials are an important step toward the realization of optical diodes, devices which transmit light in one but not in the opposite direction.

  2. Electron diffraction study of the sillenites Bi{sub 12}SiO{sub 20}, Bi{sub 25}FeO{sub 39} and Bi{sub 25}InO{sub 39}: Evidence of short-range ordering of oxygen-vacancies in the trivalent sillenites

    Energy Technology Data Exchange (ETDEWEB)

    Scurti, Craig A.; Arenas, D. J. [Department of Physics, University of North Florida, Jacksonville, FL 32224 (United States); Auvray, Nicolas [Department of Physics, University of North Florida, Jacksonville, FL 32224 (United States); Laboratoire de Nanotechnologie et d’Instrumentation Optique - UMR CNRS 6279, Université Technologie de Troyes, 12 rue Marie Curie, Troyes 10010 (France); Lufaso, Michael W. [Department of Chemistry, University of North Florida, Jacksonville, FL 32224 (United States); Takeda, Seiji [The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kohno, Hideo [School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502 Japan (Japan)

    2014-08-15

    We present an electron diffraction study of three sillenites, Bi{sub 12}SiO{sub 20}, Bi{sub 25}FeO{sub 39}, and Bi{sub 25}InO{sub 39} synthesized using the solid-state method. We explore a hypothesis, inspired by optical studies in the literature, that suggests that trivalent sillenites have additional disorder not present in the tetravalent compounds. Electron diffraction patterns of Bi{sub 25}FeO{sub 39} and Bi{sub 25}InO{sub 39} show streaks that confirm deviations from the ideal sillenite structure. Multi-slice simulations of electron-diffraction patterns are presented for different perturbations to the sillenite structure - partial substitution of the M site by Bi{sup 3+}, random and ordered oxygen-vacancies, and a frozen-phonon model. Although comparison of experimental data to simulations cannot be conclusive, we consider the streaks as evidence of short-range ordered oxygen-vacancies.

  3. Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi 2 Se 3

    KAUST Repository

    Kong, Desheng; Cha, Judy J.; Lai, Keji; Peng, Hailin; Analytis, James G.; Meister, Stefan; Chen, Yulin; Zhang, Hai-Jun; Fisher, Ian R.; Shen, Zhi-Xun; Cui, Yi

    2011-01-01

    Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from

  4. Bi-liquid foams

    International Nuclear Information System (INIS)

    Sonneville, Odile

    1997-01-01

    Concentrated emulsions have structures similar to foams; for this reason they are also called 'bi-liquid foams'. For oil in water emulsions, they are made of polyhedral oil cells separated by aqueous surfactant films. The limited stability of these Systems is a major nuisance in their applications. In this work, we tried to understand and to control the mechanisms through which bi-liquid foams can loose their stability. In a first stage, we characterized the states of surfactant films in bi-liquid foams submitted to different pressures. We determined their hydration, the surfactant density at interfaces as well as their thicknesses. The bi-liquid foams were made by concentrating hexadecane-in-water emulsions through centrifugation. The initial emulsions contained submicron oil droplets that were completely covered with surfactant. We measured the resistance of the films to dehydration, and we represented it by pressure-film thickness curves or pressure-film hydration curves. We also obtained evidence that the interfacial surfactant density increases when the film thickness is decreased (SDS case). The Newton Black Film state is the most dehydrated metastable state that can be reached. In this state, the films can be described as surfactant bilayers that only contain the hydration water of the surfactant polar heads. Two different processes are involved the destabilization of bi-liquid foams: Ostwald ripening (oil transfer from small cells to large cells) and coalescence (films rupture). The first mechanism can be controlled by choosing oils that are very insoluble in water, avoiding ethoxylated nonionic surfactants of low molecular weight, and making emulsions that are not too fine. The second mechanism is responsible for the catastrophic destabilization of bi-liquid foams made of droplets above one micron or with a low coverage in surfactant. In these cases, destabilization occurs in the early stages of concentration, when the films are still thick. It is caused

  5. Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

    KAUST Repository

    Xiong, Ka; Wang, Weichao; Alshareef, Husam N.; Gupta, Rahul P.; White, John B.; Gnade, Bruce E.; Cho, Kyeongjae

    2010-01-01

    We investigate the electronic structures and stability for Ni/Bi 2Te3, NiTe/Bi2Te3, Co/Bi 2Te3 and CoTe2/Bi2Te3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi2Te3. The interface formation energy for Co/Bi2Te3 interfaces is much lower than that of Ni/Bi2Te3 interfaces. Furthermore, we found that NiTe on Bi2Te3 is more stable than Ni, while the formation energies for Co and CoTe2 on Bi2Te3 are comparable. © 2010 IOP Publishing Ltd.

  6. Electronic structures and stability of Ni/Bi2Te3 and Co/Bi2Te3 interfaces

    KAUST Repository

    Xiong, Ka

    2010-03-04

    We investigate the electronic structures and stability for Ni/Bi 2Te3, NiTe/Bi2Te3, Co/Bi 2Te3 and CoTe2/Bi2Te3 interfaces by first-principles calculations. It is found that the surface termination strongly affects the band alignment. Ni and Co are found to form Ohmic contacts to Bi2Te3. The interface formation energy for Co/Bi2Te3 interfaces is much lower than that of Ni/Bi2Te3 interfaces. Furthermore, we found that NiTe on Bi2Te3 is more stable than Ni, while the formation energies for Co and CoTe2 on Bi2Te3 are comparable. © 2010 IOP Publishing Ltd.

  7. Exploiting strain to enhance the Bi incorporation in GaAs-based III/V semiconductors using MOVPE

    Science.gov (United States)

    Nattermann, L.; Ludewig, P.; Sterzer, E.; Volz, K.

    2017-07-01

    Bi containing III/V semiconductors are frequently mentioned for their importance as part of the next generation of optoelectronic devices. Bi containing ternary and quaternary materials like Ga(AsBi), Ga(NAsBi) or Ga(PAsBi) are promising candidates to meet the requirements for new laser structures for telecommunications and solar cell applications. However, in previous studies it was determined that the incorporation of sufficient amounts of Bi still poses a challenge, especially when using MOVPE (metalorganic vapour phase epitaxy) as the growth technique. In order to figure out which mechanisms are responsible for the limitation of Bi incorporation, this work deals with the question of whether there is a relationship between strain, induced by the large Bi atoms, and the saturation level of Bi incorporation in Ga(AsBi). Ga(NAsBi) structures were grown by MOVPE at a low temperature, 400 °C, and compared to Ga(PAsBi) as well as Ga(AsBi) growth. By using the two group V atoms P and N, which have a smaller covalent radius than Bi, the effect of local strain compensation was investigated systematically. The comparison of Bi incorporation in the two quaternary materials systems proved the importance of local strain for the limitation of Bi incorporation, in addition to other effects, like Bi surface coverage and hydrocarbon groups at the growth surface. This, of course, also opens up ways to strain-state-engineer the Bi incorporation in semiconductor alloys.

  8. Low-temperature phase MnBi compound: A potential candidate for rare-earth free permanent magnets

    International Nuclear Information System (INIS)

    Ly, V.; Wu, X.; Smillie, L.; Shoji, T.; Kato, A.; Manabe, A.; Suzuki, K.

    2014-01-01

    Highlights: • The spin reorientation temperature of MnBi is suppressed by nanoscale grain refinement. • Hardness parameter of MnBi reaches as large as 2.8 at 580 K. • MnBi has a great potential as a hard phase in rare-earth free nanocomposite magnets. • Improving the surface passivity is a remaining task for MnBi-based permanent magnets. - Abstract: The low-temperature phase (LTP) MnBi is one of the few rare-earth free compounds that exhibit a large magnetocrystalline anisotropy energy in the order of 10 6 J/m 3 . A large coercive field (μ 0 H cj ) above 1 T can be obtained readily by reducing the crystallite size (D) through mechanical grinding (MG). The room-temperature H cj values follow a phenomenological expression μ 0 H cj = μ 0 H a (δ/D) n where the anisotropy field (μ 0 H a ) is ∼4 T, the Bloch wall width (δ) is 7 nm and the exponent (n) is about 0.7 in our study. The grain refinement upon MG is accompanied by suppression of the spin reorientation transition temperature (T SR ) from 110 K to below 50 K. The coercive field starts to exhibit positive temperature dependence approximately 50 K above T SR and the room-temperature magnetic hardening induced by MG could partially be brought about by the lowered onset of this positive temperature dependence. The suppression of T SR by MG is likely to be induced by the surface anisotropy with which the 2nd order crystal field term is enhanced. One of the shortcomings of LTP-MnBi is its poor phase stability under the ambient atmosphere. The spontaneous magnetization decreases considerably after room-temperature aging for 1 week. This is due to oxidation of Mn which leads to decomposition of the MnBi phase. Hence, the surface passivity needs to be established before this material is considered for a permanent magnet in practical uses. Another shortcoming is the limited spontaneous magnetization. The theoretical upper limit of the maximum energy product in LTP-MnBi remains only a quarter of that in Nd 2

  9. Low-temperature phase MnBi compound: A potential candidate for rare-earth free permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ly, V.; Wu, X.; Smillie, L. [Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia); Shoji, T.; Kato, A.; Manabe, A. [Toyota Motor Corporation, Mishuku, Susono, Shizuoka 410-1193 (Japan); Suzuki, K., E-mail: kiyonori.suzuki@monash.edu [Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia)

    2014-12-05

    Highlights: • The spin reorientation temperature of MnBi is suppressed by nanoscale grain refinement. • Hardness parameter of MnBi reaches as large as 2.8 at 580 K. • MnBi has a great potential as a hard phase in rare-earth free nanocomposite magnets. • Improving the surface passivity is a remaining task for MnBi-based permanent magnets. - Abstract: The low-temperature phase (LTP) MnBi is one of the few rare-earth free compounds that exhibit a large magnetocrystalline anisotropy energy in the order of 10{sup 6} J/m{sup 3}. A large coercive field (μ{sub 0}H{sub cj}) above 1 T can be obtained readily by reducing the crystallite size (D) through mechanical grinding (MG). The room-temperature H{sub cj} values follow a phenomenological expression μ{sub 0}H{sub cj} = μ{sub 0}H{sub a}(δ/D){sup n} where the anisotropy field (μ{sub 0}H{sub a}) is ∼4 T, the Bloch wall width (δ) is 7 nm and the exponent (n) is about 0.7 in our study. The grain refinement upon MG is accompanied by suppression of the spin reorientation transition temperature (T{sub SR}) from 110 K to below 50 K. The coercive field starts to exhibit positive temperature dependence approximately 50 K above T{sub SR} and the room-temperature magnetic hardening induced by MG could partially be brought about by the lowered onset of this positive temperature dependence. The suppression of T{sub SR} by MG is likely to be induced by the surface anisotropy with which the 2nd order crystal field term is enhanced. One of the shortcomings of LTP-MnBi is its poor phase stability under the ambient atmosphere. The spontaneous magnetization decreases considerably after room-temperature aging for 1 week. This is due to oxidation of Mn which leads to decomposition of the MnBi phase. Hence, the surface passivity needs to be established before this material is considered for a permanent magnet in practical uses. Another shortcoming is the limited spontaneous magnetization. The theoretical upper limit of the maximum

  10. Structural and optical properties of cobalt doped multiferroics BiFeO3 nanostructure thin films

    Science.gov (United States)

    Prasannakumara, R.; Naik, K. Gopalakrishna

    2018-05-01

    Bismuth ferrite (BiFeO3) and Cobalt doped BiFeO3 (BiFe1-XCoXO3) nanostructure thin films were deposited on glass substrates by the sol-gel spin coating method. The X-ray diffraction patterns (XRD) of the grown BiFeO3 and BiFe1-XCoXO3 nanostructure thin films showed distorted rhombohedral structure. The shifting of peaks to higher angles was observed in cobalt doped BiFeO3. The surface morphology of the BiFeO3 and BiFe1-XCoXO3 nanostructure thin films were studied using FESEM, an increase in grain size was observed as Co concentration increases. The thickness of the nanostructure thin films was examined using FESEM cross-section. The EDX studies confirmed the elemental composition of the grown BiFeO3 and BiFe1-XCoXO3 nanostructure thin films. The optical characterizations of the grown nanostructure thin films were carried out using FTIR, it confirms the existence of Fe-O and Bi-O bands and UV-Visible spectroscopy shows the increase in optical band gap of the BiFeO3 nanostructure thin films with Co doping by ploting Tauc plot.

  11. Rashba split surface states in BiTeBr

    International Nuclear Information System (INIS)

    Eremeev, S V; Rusinov, I P; Nechaev, I A; Chulkov, E V

    2013-01-01

    Within density functional theory, we study the bulk band structure and surface states of BiTeBr. We consider both ordered and disordered phases, which differ in atomic order in the Te–Br sublattice. On the basis of relativistic ab initio calculations, we show that the ordered BiTeBr is energetically preferable as compared with the disordered one. We demonstrate that both Te- and Br-terminated surfaces of the ordered BiTeBr hold surface states with a giant spin–orbit splitting. The Te-terminated surface-state spin splitting has Rashba-type behavior with the coupling parameter α R ∼ 2 eVÅ. (paper)

  12. Evidence for charge transfer in Bi-based superconductors studied by positron annihilation

    International Nuclear Information System (INIS)

    Tang, Z.; Wang, S.J.; Gao, X.H.; Ce, G.C.; Zhao, Z.X.

    1993-01-01

    We have measured Doppler-broadening annihilation radiation (DBAR) spectra and positron lifetimes in normal and superconducting states for three kinds of Bi-based superconductors: Bi2212, Pb-doped Bi2223, Pb- and F-doped Bi2223. The difference spectra after deconvolution between two states show a sharpening effect with increasing temperature; the F-doped sample has the greatest amplitude in difference spectra but nearly the same positron lifetimes as the Pb-doped sample. The results are interpreted in terms of charge transfer between the Cu-O and Bi-O planes. The role of oxygen defects in charge transfer is discussed. (orig.)

  13. Structure and phase transition of BiFeO{sub 3} cubic micro-particles prepared by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jian-Ping, E-mail: zhoujp@snnu.edu.cn [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Yang, Ruo-Lin; Xiao, Rui-Juan; Chen, Xiao-Ming [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Deng, Chao-Yong [Department of Electronic Science, Guizhou University, Guizhou Guiyang 550025 (China)

    2012-11-15

    Graphical abstract: Bismuth ferrite (BiFeO{sub 3}) cubic micro-particles with smooth surfaces were synthesized. BiFeO{sub 3} has a hexagonal perovskite structure with a space group R3c below 370 °C and rhombohedral perovskite structure with a space group R3m below 755 °C, undergoes a phase transition in the temperature range of 755–817 °C to a cubic structure, then decompose to liquid and Fe{sub 2}O{sub 3} above 939 °C. Highlights: ► BiFeO{sub 3} micro-particles with smooth surface were synthesized by hydrothermal method. ► BiFeO{sub 3} enjoys hexagonal structure with well element ratio and chemical valence. ► BiFeO{sub 3} transition from rhombohedral phase to cubic phase lasts 60 °C. -- Abstract: Single-phase bismuth ferrite (BiFeO{sub 3}) powders were synthesized with a hydrothermal method by controlling the experimental conditions carefully. The powder structure, morphology and composition were characterized by using X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscope, Raman measurement and X-ray photoelectron spectroscopy. The particles change from irregular agglomerations to regular cubes with increasing KOH concentration. The large BiFeO{sub 3} cubic particles enjoy much smooth surfaces with well-matched element ratio (Bi:Fe:O = 1:1:3) and chemical valence (Bi{sup 3+}, Fe{sup 3+} and O{sup 2−}). The high temperature XRD and differential scanning calorimetry show that BiFeO{sub 3} powders have a hexagonal perovskite structure with a space group R3c below 370 °C and a rhombohedral structure with a space group R3m below 755 °C. BiFeO{sub 3} undergoes a phase transition in the temperature range of 755–817 °C from rhombohedral structure to a cubic phase, then decomposes to liquid and Fe{sub 2}O{sub 3} above 939 °C.

  14. Symmetry analysis of strain, electric and magnetic fields in the Bi2Se3-class of topological insulators

    DEFF Research Database (Denmark)

    Brems, Mathias Rosdahl; Paaske, Jens; Lunde, Anders Mathias

    2018-01-01

    velocity. The spin-momentum locking of strained Bi2Se3 is shown to be modified. Hence, strain control can be used to manipulate the spin degree of freedom via the spin–orbit coupling. We show that for a thin film of Bi2Se3 the SS band gap induced by coupling between the opposite surfaces changes opposite...... to the bulk band gap under strain. Tuning the SS band gap by strain, gives new possibilities for the experimental investigation of the thickness dependent gap and optimization of optical properties relevant for, e.g., photodetector and energy harvesting applications. We finally derive analytical expressions...... analytically the effects of strain on the electronic structure of Bi2Se3. For the most experimentally relevant surface termination we analytically derive the surface state (SS) spectrum, revealing an anisotropic Dirac cone with elliptical constant energy contours giving rise to a direction-dependent group...

  15. Selenium-assisted controlled growth of graphene–Bi_2Se_3 nanoplates hybrid Dirac materials by chemical vapor deposition

    International Nuclear Information System (INIS)

    Sun, Zhencui; Man, Baoyuan; Yang, Cheng; Liu, Mei; Jiang, Shouzhen; Zhang, Chao; Zhang, Jiaxin; Liu, Fuyan; Xu, Yuanyuan

    2016-01-01

    Graphical abstract: - Highlights: • We synthesize the graphene–Bi_2Se_3 nanoplates hybrid Dirac materials via CVD. • The Se seed layer impels the Bi_2Se_3 plates growing along the lateral direction. • The Se seed layer can supply enough Se atoms to fill the Se vacancies. • The Se seed layer can effectively avoid the interaction of Bi_2Se_3 and the graphene. • The Se seed layer can be used to control the density of the Bi_2Se_3 nanoplates. - Abstract: Se seed layers were used to synthesize the high-quality graphene–Bi_2Se_3 nanoplates hybrid Dirac materials via chemical vapor deposition (CVD) method. The morphology, crystallization and structural properties of the hybrid Dirac materials were characterized by SEM, EDS, Raman, XRD, AFM and HRTEM. The measurement results verify that the Se seed layer on the graphene surface can effectively saturate the surface dangling bonds of the graphene, which not only impel the uniform Bi_2Se_3 nanoplates growing along the horizontal direction but also can supply enough Se atoms to fill the Se vacancies. We also demonstrate the Se seed layer can effectively avoid the interaction of Bi_2Se_3 and the graphene. Further experiments testify the different Se seed layer on the graphene surface can be used to control the density of the Bi_2Se_3 nanoplates.

  16. Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

    OpenAIRE

    Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

    2015-01-01

    A new BiS2-based superconductor Bi2(O,F)S2 was discovered. This is a layered compound consisting of alternate stacking structure of rock-salt-type BiS2 superconducting layer and fluorite-type Bi(O,F) blocking layer. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2, which is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis length increased and decreased, respe...

  17. Weak antilocalization effect due to topological surface states in Bi2Se2.1Te0.9

    Science.gov (United States)

    Shrestha, K.; Graf, D.; Marinova, V.; Lorenz, B.; Chu, C. W.

    2017-10-01

    We have investigated the weak antilocalization (WAL) effect in the p-type Bi2Se2.1Te0.9 topological system. The magnetoconductance shows a cusp-like feature at low magnetic fields, indicating the presence of the WAL effect. The WAL curves measured at different tilt angles merge together when they are plotted as a function of the normal field components, showing that surface states dominate the magnetoconductance in the Bi2Se2.1Te0.9 crystal. We have calculated magnetoconductance per conduction channel and applied the Hikami-Larkin-Nagaoka formula to determine the physical parameters that characterize the WAL effect. The number of conduction channels and the phase coherence length do not change with temperature up to T = 5 K. In addition, the sample shows a large positive magnetoresistance that reaches 1900% under a magnetic field of 35 T at T = 0.33 K with no sign of saturation. The magnetoresistance value decreases with both increasing temperature and tilt angle of the sample surface with respect to the magnetic field. The large magnetoresistance of topological insulators can be utilized in future technology such as sensors and memory devices.

  18. Temporal and bi-directional associations between sleep duration and physical activity/sedentary time in children: An international comparison.

    Science.gov (United States)

    Lin, Yingyi; Tremblay, Mark S; Katzmarzyk, Peter T; Fogelholm, Mikael; Hu, Gang; Lambert, Estelle V; Maher, Carol; Maia, Jose; Olds, Timothy; Sarmiento, Olga L; Standage, Martyn; Tudor-Locke, Catrine; Chaput, Jean-Philippe

    2018-06-01

    The purpose of this multinational and cross-sectional study was to investigate whether nighttime sleep duration was associated with physical activity (PA) and sedentary time (SED) the following day, whether daytime PA/SED were associated with sleep duration the subsequent night, and whether the associations were modified by sex and study sites. Data from 5779 children aged 9-11years were analyzed. A waist-worn Actigraph GT3X+ accelerometer was used to assess children's 24-h movement behaviours for 7days, i.e. sleep duration, total SED, light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA). Multilevel linear regression models were used to account for the repeated measures nested within participants (there were up to 7 sleep→PA/SED and PA/SED→sleep pairings per participant) and schools, and adjusted for covariates. To facilitate interpretation, all sleep and PA/SED variables were standardized. Results showed that the relationship between sleep and PA/SED is bi-directional in this international sample of children. Specifically, for each one standard deviation (SD) unit increase in sleep duration, SED the following day decreased by 0.04 SD units, while LPA and MVPA increased by 0.04 and 0.02 SD units, respectively. Sleep duration decreased by 0.02 SD units and increased by 0.04 SD units for each one SD unit increase in SED and MVPA, respectively. Sleep duration was not affected by changes in LPA. These associations differed across sex and study sites in both directions. However, since the observed effect sizes are subtle, public health initiatives should consider the clinical and practical relevance of these findings. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Improving historical spelling normalization with bi-directional LSTMs and multi-task learning

    OpenAIRE

    Bollmann, Marcel; Søgaard, Anders

    2016-01-01

    Natural-language processing of historical documents is complicated by the abundance of variant spellings and lack of annotated data. A common approach is to normalize the spelling of historical words to modern forms. We explore the suitability of a deep neural network architecture for this task, particularly a deep bi-LSTM network applied on a character level. Our model compares well to previously established normalization algorithms when evaluated on a diverse set of texts from Early New Hig...

  20. Valence band structure of InAs(1-x)Bi(x) and InSb(1-x)Bi(x) alloy semiconductors calculated using valence band anticrossing model.

    Science.gov (United States)

    Samajdar, D P; Dhar, S

    2014-01-01

    The valence band anticrossing model has been used to calculate the heavy/light hole and spin-orbit split-off energies in InAs(1-x)Bi(x) and InSb(1-x)Bi(x) alloy systems. It is found that both the heavy/light hole, and spin-orbit split E + levels move upwards in energy with an increase in Bi content in the alloy, whereas the split E - energy for the holes shows a reverse trend. The model is also used to calculate the reduction of band gap energy with an increase in Bi mole fraction. The calculated values of band gap variation agree well with the available experimental data.

  1. Dependency of the properties of Sr xBi yTa2O9 thin films on the Sr and Bi stoichiometry

    International Nuclear Information System (INIS)

    Viapiana, Matteo; Schwitters, Michael; Wouters, Dirk J.; Maes, Herman E.; Van der Biest, Omer

    2005-01-01

    In this study the properties of ferroelectric SBT thin films crystallized at 700 deg. C have been investigated as function of the Sr and Bi stoichiometry. A matrix of 130 nm Sr x Bi y Ta 2 O 9 films with 0.7 ≤ x ≤ 1.0 and 2.0 ≤ y ≤ 2.4 has been realized by metal-organic spin-on deposition technique on Pt/IrO 2 /Ir/TiAlN/SiO 2 /Si substrates. Within this composition range, we found that the ferroelectric properties peak into a narrow window of 0.8 ≤ x ≤ 0.9 and y ∼ 2.25 with Pr and Ec of 6.5 μC/cm 2 and 50 kV/cm, respectively (at 2.5 V). Outside this composition window, the Pr decreases while the hysteresis loop becomes slanted. For some Sr/Bi-ratios even no ferroelectricity was achieved. 2Ec-tendencies were seen as function of the x/y-ratios, too. Examination of the microstructure of the films by scanning electron microscopy showed that film grain size increased with decreasing Sr-deficiency and that nucleation increased with increasing Bi-excess. At high Sr-deficiency and low Bi-excess, no complete crystallization of the SBT film occurs. From the film morphology, also different phases can be discriminated. X-ray diffraction analysis showed a strong correlation of the film orientation with the film composition. While our results show a clear correlation of Pr, film grain size and orientation with composition, further investigations are required to clarify the relation of the hysteresis parameters with film orientation

  2. Photoelectrochemical performance of multi-layered BiOx–TiO2/Ti electrodes for degradation of phenol and production of molecular hydrogen in water

    International Nuclear Information System (INIS)

    Park, Hyunwoong; Bak, Ayoung; Ahn, Yong Yoon; Choi, Jina; Hoffmannn, Michael R.

    2012-01-01

    Highlights: ► We demonstrated that the electrocatalytic performance of BiO x –TiO 2 anodes for the degradation of aqueous phenol could be highly boosted by light irradiation. ► Although BiO x –TiO 2 anodes have been originally developed as the electrocatalytic anodes that operate in the absence of light by degeneratively doping Bi in TiO 2 , the presence of TiO 2 made them retain photoelectrocatalytic activity as well. ► Such dual functionality of BiO x –TiO 2 electrodes with high synergy effects may be directly used for water treatment with simultaneous hydrogen production from water. - Abstract: Multi-layered BiO x –TiO 2 electrodes were used for the oxidation of chemical contaminants coupled with the production of H 2 characterized by a synergistic enhancement. The BiO x –TiO 2 electrodes were composed of a mixed-metal oxide array involving an under layer of TaO x –IrO x , a middle layer of BiO x –SnO 2 , and a top layer of BiO x –TiO 2 deposited in a series on both sides of Ti foil. Cyclic voltammograms showed that the BiO x –TiO 2 electrodes had an electrocatalytic activity for oxidation of phenol that was enhanced by 70% under illumination with AM 1.5 light. When the BiO x –TiO 2 anode was coupled with a stainless steel cathode in a Na 2 SO 4 electrolyte with phenol and irradiated with UV light at an applied DC voltage, the anodic phenol oxidation rate and the cathodic H 2 production rates were enhanced by factors of four and three, respectively, as compared to the sum of each light irradiation and direct DC electrolysis. These synergistic effects depend on the specific electrode composition and decrease on TaO x –IrO x and BiO x –SnO 2 anodes in the absence of a top layer of BiO x –TiO 2 . These results indicate that the BiO x –TiO 2 layer functions as the key photo-electrocatalyst. The heavy doping level of Bi (25 mol%) in TiO 2 increases the electric conductivity of the parent TiO 2 .

  3. Synthesis of belt-like BiOBr hierarchical nanostructure with high photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haiping [National Engineering Technology Research Center for Colloidal Materials, Shandong University, Jinan 250100 (China); Liu, Jingyi; Hu, Tingxia [Environment Research Institute, Shandong University, Jinan 250100 (China); Du, Na; Song, Shue [Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100 (China); Hou, Wanguo, E-mail: wghou@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100 (China)

    2016-05-15

    Highlights: • BiOBr hierarchical nanobelts (NBs) were solvothermally prepared. • NBs show higher specific surface area and photoabsorption than BiOBr nanosheets. • NBs exhibit higher photoactivity than the nanosheets. - Abstract: One-dimensional (1D) bismuth oxyhalide (BiOX) hierarchical nanostructures are always difficult to prepare. Herein, we report, for the first time, a simple synthesis of BiOBr nanobelts (NBs) via a facile solvothermal route, using bismuth subsalicylate as the template and bismuth source. The BiOBr nanobelts are composed of irregular single crystal nanoparticles with highly exposed (0 1 0) facets. Compared with the BiOBr nanosheets (NSs) with dominant exposed (0 0 1) facets, they exhibit higher photocatalytic activity toward degradation of Rhodamine B and Methylene Blue under visible light irradiation. The higher photocatalytic performance of BiOBr NBs arises from their larger specific surface area and higher photoabsorption capability. This study provides a simple route for synthesis of belt-like Bi-based hierarchical nanostructures.

  4. Photocatalytic Degradation of Methyl Orange on Bi2O3 and Ag2O-Bi2O3 Nano Photocatalysts

    Directory of Open Access Journals (Sweden)

    Seyed Ali Hosseini

    2017-04-01

    Full Text Available The photocatalytic activity of Bi2O3 and Ag2O-Bi2O3 was evaluated by degradation of aqueous methyl orange as a model dye effluent. Bi2O3 was synthesized using chemical precipitation method. Structural analysis revealed that Bi2O3 contain a unique well-crystallized phase and the average crystallite size of 22.4 nm. The SEM analysis showed that the size of Bi2O3 particles was mainly in the range of 16-22 nm. The most important variables affecting the photocatalytic degradation of dyes, namely reaction time, initial pH and catalyst dosage were studied, and their optimal amounts were found at 60 min, 5.58 and 0.025 g, respectively. A good correlation was found between experimental and predicted responses, confirming the reliability of the model. Incorporation of Ag2O in the structure of composite caused decreasing band gap and its response to visible light. Because a high percentage of sunlight is visible light, hence Ag2O-Bi2O3 nano-composite could be used as an efficient visible light driven photocatalyst for degradation of dye effluents by sunlight. Copyright © 2017 BCREC GROUP. All rights reserved Received: 15th August 2016; Revised: 20th December 2016; Accepted: 21st December 2016 How to Cite: Hosseini, S.A., Saeedi, R. (2017. Photocatalytic Degradation of Methyl Orange on Bi2O3 and Ag2O-Bi2O3 Nano Photocatalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (1: 96-105 (doi:10.9767/bcrec.12.1.623.96-105 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.1.623.96-105

  5. Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

    Science.gov (United States)

    Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

    2015-02-01

    A new BiS2-based superconductor, Bi2(O,F)S2, was discovered. It is a layered compound consisting of alternately stacked structure of rock-salt-type BiS2 superconducting layers and fluorite-type Bi(O,F) blocking layers. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2. This is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis lengths increased and decreased, respectively, and Tc increased to 5.1 K.

  6. Photoluminescence of electron beam evaporated CaS:Bi thin films

    CERN Document Server

    Smet, P F; Poelman, D R; Meirhaeghe, R L V

    2003-01-01

    For the first time, the photoluminescence (PL) of electron beam evaporated CaS:Bi thin films is reported. Luminescent CaS:Bi powder prepared out of aqueous solutions was used as source material. The influence of substrate temperature on the PL and the morphology of thin films is discussed, and an optimum is determined. Substrate temperatures between 200 deg. C and 300 deg. C lead to good quality thin films with sufficient PL intensity. As-deposited thin films show two emission bands, peaking at 450 and 530 nm. Upon annealing the emission intensity increases, and annealing at 800 deg. C is sufficient to obtain a homogeneously blue emitting thin film (CIE colour coordinates (0.17; 0.12)), thanks to a single remaining emission band at 450 nm. The influence of ambient temperature on the PL of CaS:Bi powder and thin films was also investigated and it was found that CaS:Bi thin films show a favourable thermal quenching behaviour near room temperature.

  7. BUSINESS INTELLIGENCE ADOPTION IN LARGE ROMANIAN COMPANIES

    Directory of Open Access Journals (Sweden)

    Flavia CAIA

    2014-11-01

    Full Text Available The economic conditions and market competition create pressures on companies to adopt new technologies that can provide more efficient information and can support decision-making better. The purpose of the research is to investigate the decision support information systems in order to apprise and enhance the capacity of the entities to apply the new knowledge that BI produces for organizational success and competitiveness. The importance of the conducted research consists in identifying solutions to improve reporting and stimulate the entities to start using business intelligence (BI technologies, which facilitate obtaining new information, in order to ensure flexibility, resilience and provide answers to questions that go beyond what the pre-defined reports can do to support decision-making. The estimated result is a technical and operational overview of the large companies in Romania, drawing future directions for an improved competitive behaviour and strategic awareness, and identifying the significant factors for optimizing the decision-making process.

  8. Evidence for oxygen vacancy or ferroelectric polarization induced switchable diode and photovoltaic effects in BiFeO3 based thin films

    International Nuclear Information System (INIS)

    Guo Yiping; Guo Bing; Dong Wen; Li Hua; Liu Hezhou

    2013-01-01

    The diode and photovoltaic effects of BiFeO 3 and Bi 0.9 Sr 0.1 FeO 3−δ polycrystalline thin films were investigated by poling the films with increased magnitude and alternating direction. It was found that both electromigration of oxygen vacancies and polarization flipping are able to induce switchable diode and photovoltaic effects. For the Bi 0.9 Sr 0.1 FeO 3−δ thin films with high oxygen vacancy concentration, reversibly switchable diode and photovoltaic effects can be observed due to the electromigration of oxygen vacancies under an electric field much lower than its coercive field. However, for the pure BiFeO 3 thin films with lower oxygen vacancy concentration, the reversibly switchable diode and photovoltaic effect is hard to detect until the occurrence of polarization flipping. The switchable diode and photovoltaic effects can be explained well using the concepts of Schottky-like barrier-to-Ohmic contacts resulting from the combination of oxygen vacancies and polarization. The sign of photocurrent could be independent of the direction of polarization when the modulation of the energy band induced by oxygen vacancies is large enough to offset that induced by polarization. The photovoltaic effect induced by the electromigration of oxygen vacancies is unstable due to the diffusion of oxygen vacancies or the recombination of oxygen vacancies with hopping electrons. Our work provides deep insights into the nature of diode and photovoltaic effects in ferroelectric films, and will facilitate the advanced design of switchable devices combining spintronic, electronic, and optical functionalities. (paper)

  9. Preparation of BiVO4-Graphene Nanocomposites and Their Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Xuan Xu

    2014-01-01

    Full Text Available We prepared BiVO4-graphene nanocomposites by using a facile single-step method and characterized the material by x-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, ultraviolet-visible diffuse-reflection spectroscopy, and three-dimensional fluorescence spectroscopy. The results show that graphene oxide in the catalyst was thoroughly reduced. The BiVO4 is densely dispersed on the graphene sheets, which facilitates the transport of electrons photogenerated in BiVO4, thereby leading to an efficient separation of photogenerated carriers in the coupled graphene-nanocomposite system. For degradation of rhodamine B dye under visible-light irradiation, the photocatalytic activity of the synthesized nanocomposites was over ∼20% faster than for pure BiVO4 catalyst. To study the contribution of electrons and holes in the degradation reaction, silver nitrate and potassium sodium tartrate were added to the BiVO4-graphene photocatalytic reaction system as electron-trapping agent and hole-trapping agent, respectively. The results show that holes play the main role in the degradation of rhodamine B.

  10. Enhanced magnetic and ferroelectric properties in scandium doped nano Bi2Fe4O9

    International Nuclear Information System (INIS)

    Dutta, Dimple P.; Sudakar, C.; Mocherla, Pavana S.V.; Mandal, Balaji P.; Jayakumar, Onnatu D.; Tyagi, Avesh K.

    2012-01-01

    In this study we report the synthesis of undoped and Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles using sonochemical technique. X-ray diffraction reveals that all samples are single phase with no impurities detected. EDS analysis was done to confirm the extent of Sc 3+ doping in the samples. The size and morphology of the nanoparticles have been analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Bi 2 Fe 4 O 9 nanoparticles show a weak ferromagnetic behavior at room temperature, which is quite different from the linear M–H relationship reported for bulk Bi 2 Fe 4 O 9 . A magnetization of 0.144 μB/f.u. is obtained at 300 K, which is mainly attributed to the uncompensated moments at the disordered particle surface resulting from the reduced coordination of the surface spins, arising due to lattice strain or oxygen deficiency. Addition of Sc 3+ dopant in varying concentrations in these Bi 2 Fe 4 O 9 nanoparticles, improves their magnetic as well as ferroelectric properties. The leakage current is considerably reduced and electric polarization increases significantly in case of Bi 2 Fe 4(1−x) Sc x O 9 (x = 0.1) nanoparticles. Thus it can be inferred that Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles shows promise as good multiferroic materials. -- Graphical abstract: Undoped and Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles have been synthesized using sonochemical technique. The bi-functionalities of Sc 3+ doped Bi 2 Fe 4 O 9 nanoparticles have been demonstrated. The Bi 2 Fe 4(1−x) Sc x O 9 (x = 0.1) nanoparticles showed enhanced magnetic and ferroelectric properties with considerably less lossy characteristics compared to the bulk Bi 2 Fe 4 O 9 . Highlights: ► Phase pure Bi 2 Fe 4 O 9 nanostructures synthesized using a facile sonochemical technique. ► Nanoparticles show a weak ferromagnetic order at room temperature. ► Sc 3+ doping in Bi 2 Fe 4 O 9 nanoparticles alters their magnetic and ferroelectric properties. ► A

  11. Rotational Symmetry Breaking in a Trigonal Superconductor Nb-doped Bi_{2}Se_{3}

    Directory of Open Access Journals (Sweden)

    Tomoya Asaba

    2017-01-01

    Full Text Available The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi_{2}Se_{3} is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb-doped Bi_{2}Se_{3}. As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi_{2}Se_{3}.

  12. Non-noble metal Bi deposition by utilizing Bi2WO6 as the self-sacrificing template for enhancing visible light photocatalytic activity

    Science.gov (United States)

    Yu, Shixin; Zhang, Yihe; Li, Min; Du, Xin; Huang, Hongwei

    2017-01-01

    Bi metal deposited on Bi2WO6 composite photocatalysts have been successfully synthesized via a simple in-situ reduction method at room temperature with using Bi2WO6 as self-sacrificing template and NaBH4 as reducing agent. The reduction extent can be easily modulated by controlling the concentration of NaBH4 solution. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectra, N2 adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), diffuse reflection spectroscopy (DRS) and photoelectrochemical measurements were carried out to analyze the phase, morphology, optical property and photoelectrochemical property of the as-prepared samples. The photocatalytic activity is surveyed by degradation of phenol under visible light (λ > 420 nm), which showed that the BWO-0.2 photocatalyst exhibited the highest efficiency, which was over 3 times as high as pure Bi2WO6. The enhanced photocatalytic activity should be attributed to strengthened photoabsorption and charge separation efficiency derived from the surface plasmon resonance (SPR) of Bi metal.

  13. A new high-spin isomer in {sup 195}Bi

    Energy Technology Data Exchange (ETDEWEB)

    Roy, T.; Mukherjee, G.; Rana, T.K.; Bhattacharya, Soumik; Asgar, Md.A.; Bhattacharya, C.; Bhattacharya, S.; Bhattacharyya, S.; Pai, H. [Variable Energy Cyclotron Centre, Kolkata (India); Madhavan, N.; Bala, I.; Gehlot, J.; Gurjar, R.K.; Jhingan, A.; Kumar, R.; Muralithar, S.; Nath, S.; Singh, R.P.; Varughese, T. [Inter University Acclerator Centre, New Delhi (India); Basu, K.; Bhattacharjee, S.S.; Ghugre, S.S.; Raut, R.; Sinha, A.K. [UGC-DAE-CSR Kolkata Centre, Kolkata (India); Palit, R. [Tata Institute of Fundamental Research, Department of Nuclear and Atomic Physics, Mumbai (India)

    2015-11-15

    A new high-spin isomer has been identified in {sup 195}Bi at the focal plane of the HYbrid Recoil mass Analyser (HYRA) used in the gas-filled mode. The fusion evaporation reactions {sup 169}Tm ({sup 30}Si, x n) {sup 193,} {sup 195}Bi were used with the beam energies on targets of 168 and 146MeV for 6n and 4n channels, respectively. The evaporation residues, separated from the fission fragments, and their decays were detected at the focal plane of HYRA using MWPC, Si-Pad and clover HPGe detectors. The half-life of the new isomer in {sup 195}Bi has been measured to be 1.6(1) μs. The configuration of the new isomer has been proposed and compared with the other isomers in this region. The Total Routhian Surface (TRS) calculations for the three-quasiparticle configurations corresponding to the new isomer suggest an oblate deformation for this isomeric state. The same calculations for different configurations in {sup 195}Bi and for the even-even {sup 194}Pb core indicate that the proton i{sub 13/2} orbital has a large shape driving effect towards oblate shape in these nuclei. (orig.)

  14. Visible-light photocatalytic activity of graphene oxide-wrapped Bi2WO6 hierarchical microspheres

    Science.gov (United States)

    Zhai, Jiali; Yu, Hongwen; Li, Haiyan; Sun, Lei; Zhang, Kexin; Yang, Hongjun

    2015-07-01

    A facile approach of fabricating homogeneous graphene oxide (GO)-wrapped Bi2WO6 microspheres (GO/Bi2WO6) is developed. The transmission electron microscopy (TEM) results show that a heterojunction interface between GO and Bi2WO6. The UV-vis diffuse reflection spectra (DRS) reveal that the as-prepared GO/Bi2WO6 composites own more intensive absorption in the visible light range compared with pure Bi2WO6. These characteristic structural and optical properties endow GO/Bi2WO6 composites with enhanced photocatalytic activity. The enhanced photocatalytic activity of the GO/Bi2WO6 is attributed predominantly to the synergetic effect between GO and Bi2WO6, causing rapid generation and separation of photo-generated charge carriers.

  15. Partial enthalpies of Bi and Te in Bi-Te melts and of In and Te in In-Te melts

    International Nuclear Information System (INIS)

    Yassin, Abeer; Amzil, Abdelhamid; Castanet, Robert

    2000-01-01

    Full text.Calorimetric measurement are reported which allow the enthalpic behaviour of Bi-Te melts to be established. Further work is required, however, to supplement results obtained for In-Te melts. The partial enthalpies of bismuth and tellurium in the Bi-Te melts at 755K and those of indium and tellurium in the In-Te melts at 1010 and 987K were measured at high dilution by direct reaction calorimetry (drop method) with the help of a Tian-Calvet calorimeter. The limiting partial enthalpies of the components were deduced by extrapolation at infinite dilution: Δh f,∞ B i(755K)/KJ.mol -1 = -34.0 and Δh f,∞ Te(755K) /KJ·mol -1 = -24.1 in the Bi-Te melts Δh f,∞ In(1010K) /KJ·mol -1 = -75.9 and Δh f,∞ Te(1010K) /KJ·mol -1 = -47.8 in the In-Te melts Δh f,∞ In(987K) /KJ·mol -1 = -75.2 and Δh f,∞ Te(987K) /KJ·mol -1 = -48.0 in the In-Te melts

  16. Damage evolution of bi-body model composed of weakly cemented soft rock and coal considering different interface effect.

    Science.gov (United States)

    Zhao, Zenghui; Lv, Xianzhou; Wang, Weiming; Tan, Yunliang

    2016-01-01

    Considering the structure effect of tunnel stability in western mining of China, three typical kinds of numerical model were respectively built as follows based on the strain softening constitutive model and linear elastic-perfectly plastic model for soft rock and interface: R-M, R-C(s)-M and R-C(w)-M. Calculation results revealed that the stress-strain relation and failure characteristics of the three models vary between each other. The combination model without interface or with a strong interface presented continuous failure, while weak interface exhibited 'cut off' effect. Thus, conceptual models of bi-material model and bi-body model were established. Then numerical experiments of tri-axial compression were carried out for the two models. The relationships between stress evolution, failure zone and deformation rate fluctuations as well as the displacement of interface were detailed analyzed. Results show that two breakaway points of deformation rate actually demonstrate the starting and penetration of the main rupture, respectively. It is distinguishable due to the large fluctuation. The bi-material model shows general continuous failure while bi-body model shows 'V' type shear zone in weak body and failure in strong body near the interface due to the interface effect. With the increasing of confining pressure, the 'cut off' effect of weak interface is not obvious. These conclusions lay the theoretical foundation for further development of constitutive model for soft rock-coal combination body.

  17. Facile one-pot transformation using structure-guided combustion waves of micro-nanostructured β-Bi2O3 to α-Bi2O3@C and analysis of electrochemical capacitance

    Science.gov (United States)

    Hwang, Hayoung; Shin, Jung-ho; Lee, Kang Yeol; Choi, Wonjoon

    2018-01-01

    Precise phase-transformation can facilitate control of the properties of various materials, while an organic coating surrounding inorganic materials can yield useful characteristics. Herein, we demonstrate facile, selective manipulation of micro-nanostructured bismuth oxide (Bi2O3) for phase transformation from microflower-like β-Bi2O3 to micropill-like α-Bi2O3, with carbon-coating layer deposition, using structure-guided combustion waves (SGCWs). Microflower-like β-Bi2O3 are synthesized as core materials and nitrocellulose is coated on their surfaces for the formation of core-shell hybrid structures of Bi2O3 and chemical fuel. The SGCWs, which propagate along the core-material and fuel interfaces, apply high thermal energy (550-600 °C) and deposit incompletely combusted carbonaceous fuel on the microflower-like β-Bi2O3 to enable transformation to α-phase and carbon-coating-layer synthesis. SGCW-induced improvements to the electrochemical characteristics of the developed micropill-like α-Bi2O3@C, compared with the microflower-like β-Bi2O3, are investigated. The enhanced stability from the α-phase Bi2O3 and micropill-like structures during charge-discharge cycling improves the specific capacitance, while the carbon-coating layers facilitate increased electrical conductivity. SGCW-based methods exhibit high potential for selective phase manipulation and synthesis of carbon coatings surrounding micro-nanomaterials. They constitute a low-cost, fast, large-scale process for metal oxides, ceramics, and hybrid materials, implemented through control of the processing parameters by tuning the temperature, chemical fuel, and ambient conditions.

  18. Electroforming of Bi(1-x)Sb(x) nanowires for high-efficiency micro-thermoelectric cooling devices on a chip.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Webb, Edmund Blackburn, III (,; ); Siegal, Michael P.; Yelton, William Graham

    2006-11-01

    Active cooling of electronic systems for space-based and terrestrial National Security missions has demanded use of Stirling, reverse-Brayton, closed Joule-Thompson, pulse tube and more elaborate refrigeration cycles. Such cryocoolers are large systems that are expensive, demand large powers, often contain moving parts and are difficult to integrate with electronic systems. On-chip, solid-state, active cooling would greatly enhance the capabilities of future systems by reducing the size, cost and inefficiencies compared to existing solutions. We proposed to develop the technology for a thermoelectric cooler capable of reaching 77K by replacing bulk thermoelectric materials with arrays of Bi{sub 1-x}Sb{sub x} nanowires. Furthermore, the Sandia-developed technique we will use to produce the oriented nanowires occurs at room temperature and can be applied directly to a silicon substrate. Key obstacles include (1) optimizing the Bi{sub 1-x}Sb{sub x} alloy composition for thermoelectric properties; (2) increasing wire aspect ratios to 3000:1; and (3) increasing the array density to {ge} 10{sup 9} wires/cm{sup 2}. The primary objective of this LDRD was to fabricate and test the thermoelectric properties of arrays of Bi{sub 1-x}Sb{sub x} nanowires. With this proof-of-concept data under our belts we are positioned to engage National Security systems customers to invest in the integration of on-chip thermoelectric coolers for future missions.

  19. The BiCu{sub 1−x}OS oxysulfide: Copper deficiency and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Berthebaud, D.; Guilmeau, E.; Lebedev, O.I. [Laboratoire CRISMAT, UMR 6508 CNRS/ENSICAEN/UCBN, 6 bd du Maréchal Juin, F-14050 CAEN Cedex 4 (France); Maignan, A., E-mail: antoine.maignan@ensicaen.fr [Laboratoire CRISMAT, UMR 6508 CNRS/ENSICAEN/UCBN, 6 bd du Maréchal Juin, F-14050 CAEN Cedex 4 (France); Gamon, J.; Barboux, P. [Institut de Recherche de Chimie de Paris, Ecole Nationale Supérieure de Chimie de Paris, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 09 France (France)

    2016-05-15

    An oxysulfide series of nominal compositions BiCu{sub 1−x}OS with x<0.20 has been prepared and its structural properties characterized by combining powder X-ray diffraction and transmission electron microscopy techniques. It is found that this oxysulfide, crystallizing in the P4/nmm space group, tends to adopt a constant amount of copper vacancy corresponding to x=0.05 in the BiCu{sub 1−x}OS formula. The presence of Cu vacancies is confirmed by HAADF-STEM analysis showing, in the Cu atomic columns, alternating peaks of different intensities in some very localized regions. For larger Cu deficiencies (x>0.05 in the nominal composition), other types of structural nanodefects are evidenced such as bismuth oxysulfides of the “BiOS” ternary system which might explain the report of superconductivity for the BiCu{sub 1−x}OS oxysulfide. Local epitaxial growth of the BiCuOS oxysulfide on top of CuO is also observed. In marked contrast to the BiCu{sub 1−x}OSe oxyselenide, these results give an explanation to the limited impact of Cu deficiency on the Seebeck coefficient in BiCu{sub 1−x}OS compounds. - Graphical abstract: High resolution TEM image showing a Bi(Cu)OS/Bi{sub 2}O{sub 2}S interface and corresponding dislocation region. The Bi(Cu)OS structure adopts a rather constant Cu content (near 0.95); starting from BiCuOS leads to the formation of defects such as the Bi{sub 2}O{sub 2}S oxysulfide.

  20. Novel composition above the limit of Bi:Zr solid solution; synthesis and physical properties of Bi1.33Zr0.67O3+δ

    International Nuclear Information System (INIS)

    Meatza, Iratxe de; Chapman, Jon P.; Mauvy, Fabrice; Larramendi, Jose I. Ruiz de; Arriortua, Maria I.; Rojo, Teofilo

    2004-01-01

    This paper presents an increase to x = 0.67 of the zirconium content in the conductive Bi 2-x Zr x O 3+δ solid solution. Complete incorporation of Zr in the β III -Bi 2 O 3 structure, confirmed by X-ray powder diffraction, has produced a phase with a lower volume and superior conductivity than those predicted by an earlier study. The observed β III -δ Bi 2-x Zr x O 3+δ phase transition around 730 deg. C has been characterised for the first time and shows a segregation of a mixture of predominantly γ-Bi 2 O 3 and approximately 30% of the ZrO 2 , before total reincorporation of the Zr in the high temperature δ-phase

  1. The tensor bi-spectrum in a matter bounce

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Debika; Sreenath, V.; Sriramkumar, L., E-mail: debika@physics.iitm.ac.in, E-mail: sreenath@lsu.edu, E-mail: sriram@physics.iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2015-11-01

    Matter bounces are bouncing scenarios wherein the universe contracts as in a matter dominated phase at early times. Such scenarios are known to lead to a scale invariant spectrum of tensor perturbations, just as de Sitter inflation does. In this work, we examine if the tensor bi-spectrum can discriminate between the inflationary and the bouncing scenarios. Using the Maldacena formalism, we analytically evaluate the tensor bi-spectrum in a matter bounce for an arbitrary triangular configuration of the wavevectors. We show that, over scales of cosmological interest, the non-Gaussianity parameter h{sub NL} that characterizes the amplitude of the tensor bi-spectrum is quite small when compared to the corresponding values in de Sitter inflation. During inflation, the amplitude of the tensor perturbations freeze on super-Hubble scales, a behavior that results in the so-called consistency condition relating the tensor bi-spectrum and the power spectrum in the squeezed limit. In contrast, in the bouncing scenarios, the amplitude of the tensor perturbations grow strongly as one approaches the bounce, which suggests that the consistency condition will not be valid in such situations. We explicitly show that the consistency relation is indeed violated in the matter bounce. We discuss the implications of the results.

  2. Charge carrier localised in zero-dimensional (CH3NH3)3Bi2I9 clusters.

    Science.gov (United States)

    Ni, Chengsheng; Hedley, Gordon; Payne, Julia; Svrcek, Vladimir; McDonald, Calum; Jagadamma, Lethy Krishnan; Edwards, Paul; Martin, Robert; Jain, Gunisha; Carolan, Darragh; Mariotti, Davide; Maguire, Paul; Samuel, Ifor; Irvine, John

    2017-08-01

    A metal-organic hybrid perovskite (CH 3 NH 3 PbI 3 ) with three-dimensional framework of metal-halide octahedra has been reported as a low-cost, solution-processable absorber for a thin-film solar cell with a power-conversion efficiency over 20%. Low-dimensional layered perovskites with metal halide slabs separated by the insulating organic layers are reported to show higher stability, but the efficiencies of the solar cells are limited by the confinement of excitons. In order to explore the confinement and transport of excitons in zero-dimensional metal-organic hybrid materials, a highly orientated film of (CH 3 NH 3 ) 3 Bi 2 I 9 with nanometre-sized core clusters of Bi 2 I 9 3- surrounded by insulating CH 3 NH 3 + was prepared via solution processing. The (CH 3 NH 3 ) 3 Bi 2 I 9 film shows highly anisotropic photoluminescence emission and excitation due to the large proportion of localised excitons coupled with delocalised excitons from intercluster energy transfer. The abrupt increase in photoluminescence quantum yield at excitation energy above twice band gap could indicate a quantum cutting due to the low dimensionality.Understanding the confinement and transport of excitons in low dimensional systems will aid the development of next generation photovoltaics. Via photophysical studies Ni et al. observe 'quantum cutting' in 0D metal-organic hybrid materials based on methylammonium bismuth halide (CH 3 NH 3 )3Bi 2 I 9 .

  3. Enhanced motor learning with bilateral transcranial direct current stimulation: Impact of polarity or current flow direction?

    Science.gov (United States)

    Naros, Georgios; Geyer, Marc; Koch, Susanne; Mayr, Lena; Ellinger, Tabea; Grimm, Florian; Gharabaghi, Alireza

    2016-04-01

    Bilateral transcranial direct current stimulation (TDCS) is superior to unilateral TDCS when targeting motor learning. This effect could be related to either the current flow direction or additive polarity-specific effects on each hemisphere. This sham-controlled randomized study included fifty right-handed healthy subjects in a parallel-group design who performed an exoskeleton-based motor task of the proximal left arm on three consecutive days. Prior to training, we applied either sham, right anodal (a-TDCS), left cathodal (c-TDCS), concurrent a-TDCS and c-TDCS with two independent current sources and return electrodes (double source (ds)-TDCS) or classical bilateral stimulation (bi-TDCS). Motor performance improved over time for both unilateral (a-TDCS, c-TDCS) and bilateral (bi-TDCS, ds-TDCS) TDCS montages. However, only the two bilateral paradigms led to an improvement of the final motor performance at the end of the training period as compared to the sham condition. There was no difference between the two bilateral stimulation conditions (bi-TDCS, ds-TDCS). Bilateral TDCS is more effective than unilateral stimulation due to its polarity-specific effects on each hemisphere rather than due to its current flow direction. This study is the first systematic evaluation of stimulation polarity and current flow direction of bi-hemispheric motor cortex TDCS on motor learning of proximal upper limb muscles. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  4. Quantum confinement of Bi2S3 in glass with magnetic behavior

    Directory of Open Access Journals (Sweden)

    Rajendra P. Panmand

    2013-02-01

    Full Text Available The novel Bi2S3 quantum dots (QDs glass nanosystems with unique magnetic properties have been investigated. The monodispersed QDs of size in the range of 3 to 15 nm were grown in the glass matrix. The optical study of these nanosystems clearly demonstrated the size quantization effect resulting in a pronounced band gap variation with QD size. The magnetic properties of the pristine glass and the Bi2S3 QD glass nanosystems were investigated by VSM and SQUID magnetometer. The pristine glass did not show any ferromagnetism while the Bi2S3 glass nanosystems showed significant and reproducible ferromagnetism. We also investigated the effect of the size of Bi2S3 QDs on the magnetic properties. The saturation magnetization for the 15 nm QD glass-nanosystem (124 memu/g was observed to be higher as compared to the 3nm QD glass nanosystem (58.2 memu/g. The SQUID measurement gave the excellent hysteresis up to 300K. Surprisingly, the bulk Bi2S3 powder is diamagnetic in nature but Bi2S3 quantum dots glass nanosystem showed the ferromagnetic behavior for the first time. The investigated novel QD glass-nanosystem may have a potential application in spintronic devices and most importantly, this nanosystem can be fabricated in any usable shape as per the device requirement.

  5. Zener diode controls switching of large direct currents

    Science.gov (United States)

    1965-01-01

    High-current zener diode is connected in series with the positive input terminal of a dc supply to block the flow of direct current until a high-frequency control signal is applied across the zener diode. This circuit controls the switching of large dc signals.

  6. Electric and Magnetic Properties of Sputter Deposited BiFeO3 Films

    Directory of Open Access Journals (Sweden)

    N. Siadou

    2013-01-01

    Full Text Available Polycrystalline BiFeO3 films have been magnetron sputter deposited at room temperature and subsequently heat-treated ex situ at temperatures between 400 and 700°C. The deposition was done in pure Ar atmosphere, as the use of oxygen-argon mixture was found to lead to nonstoichiometric films due to resputtering effects. At a target-to-substrate distance d=2′′ the BiFeO3 structure can be obtained in larger range process gas pressures (2–7 mTorr but the films do not show a specific texture. At d=6′′ codeposition from BiFeO3 and Bi2O3 has been used. Films sputtered at low rate tend to grow with the (001 texture of the pseudo-cubic BiFeO3 structure. As the film structure does not depend on epitaxy similar results are obtained on different substrates. A result of the volatility of Bi, Bi rich oxide phases occur after heat treatment at high temperatures. A Bi2SiO5 impurity phase forms on the substrate side, and does not affect the properties of the main phase. Despite the deposition on amorphous silicon oxide substrate weak ferromagnetism phenomena and displaced loops have been observed at low temperatures showing that their origin is not strain. Ba, La, Ca, and Sr doping suppress the formation of impurity phases and leakage currents.

  7. Silicon nanodot formation and self-ordering under bombardment with heavy Bi3 ions

    International Nuclear Information System (INIS)

    Boettger, Roman; Heinig, Karl-Heinz; Bischoff, Lothar; Liedke, Bartosz; Huebner, Rene; Pilz, Wolfgang

    2013-01-01

    Si nanodots of high density and hexagonal short-range order are observed upon normal-incidence bombardment of hot, crystalline Si with Bi 3 + ions having a kinetic energy of a few tens of keV. The heights of nanodots are comparable to their widths of ∝20 nm. The implanted Bi accumulates in tiny Bi nanocrystals in a thin Si top layer which is amorphous due to implantation damage. Light and heavy ions up to Xe cause smoothing of surfaces, but Bi 3 + ions considered here have a much higher mass. Atomistic simulations prove that each Bi 3 + impact deposits an extremely high energy density resulting in a several nanometer large melt pool, which resolidifies within a few hundreds of picoseconds. Experiments confirm that dot patterns form only if the deposited energy density exceeds the threshold for melting. Comparing monatomic and polyatomic Bi ion irradiation, Bi-Si phase separation and preferential ion erosion are ruled out as driving forces of pattern formation. A model based on capillary forces in the melt pool explains the pattern formation consistently. High-density Si nanodots are formed by polyatomic Bi ion irradiation of hot Si surfaces. Each impact causes local transient melt pools smaller than the dots. Hexagonally ordered patterns evolve by self-organization driven by repeated ion-induced melting of tiny volumes. Homogeneously distributed Bi nanocrystals are found in the a-Si film. These nanocrystals are related to particularities of the Si-Bi phase diagram. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Investigation of the electronic structure of the BiSBr and BiSeBr clusters by density functional method

    International Nuclear Information System (INIS)

    Audzijonis, A.; Gaigalas, G.; Zigas, L.; Pauliukas, A.; Zaltauskas, R.; Kvedaravicius, A.; Cerskus, A.

    2008-01-01

    The energy levels of valence bands (VB) of the BiSBr and BiSeBr crystals have been calculated for investigation of the photoelectron emission spectra of BiSBr, BiSeBr and BiSI crystals. The molecular model of this crystal has been used for the calculation of VB by the Density Functional Theory (DFT) method. The molecular cluster, consisting of 20 molecules of BiSBr, BiSeBr, has been used for calculations of averaged total density of states, including atom vibrations. The spectra of the averaged total density of states from VB of BiSBr and BiSeBr clusters have been compared with the experimental photoelectron emission spectra from VB of BiSI crystals. The results clarify that the atomic vibrations in A 5 B 6 C 7 type crystals with chain structure create a smoother appearance of the averaged total density of state spectrum and the experimental X-ray photoemission spectra (XPS)

  9. Magnetic and thermoelectric properties of three different atomic ratio of Bi/Mn in BiMn2O5: DFT approach

    International Nuclear Information System (INIS)

    Khan, Wilayat; Reshak, A.H.; Rafezi Ahmad, Khairel; Alahmed, Z.A.

    2014-01-01

    Electronic structure and magnetic properties of the three different samples of BiMn 2 O 5 , are calculated using the density functional theory (DFT). These samples have different Bi/Mn concentration. For simplicity, we suggest to call them as A, B and C. The calculated band structures show half metallicity for all samples, and possess 100% spin polarization at the Fermi level. The spin up/down density of states are calculated using Engel–Vosko generalized gradient approximation (EV-GGA). We have discussed the effect of Mn magnetic moment (μ B ) on the electronic and magnetic properties of the entire samples. The temperature dependent thermoelectric properties like electrical and thermal conductivity, Seebeck coefficient and power factor are also calculated, employing the Boltzmann transport theory under the BoltzTraP code. Our results indicated that these properties are strongly dependent on Bi/Mn concentration. - Highlights: • FPLAPW method used for calculating the electronic Structure. • The band structure shows that the calculated compounds are half metallic. • The magnetic properties have been calculated. • Thermoelectric properties were also calculated using Boltzmann theory. • Calculated power factor shows that sample B are good thermoelectric material

  10. Extracting BI-RADS Features from Portuguese Clinical Texts.

    Science.gov (United States)

    Nassif, Houssam; Cunha, Filipe; Moreira, Inês C; Cruz-Correia, Ricardo; Sousa, Eliana; Page, David; Burnside, Elizabeth; Dutra, Inês

    2012-01-01

    In this work we build the first BI-RADS parser for Portuguese free texts, modeled after existing approaches to extract BI-RADS features from English medical records. Our concept finder uses a semantic grammar based on the BIRADS lexicon and on iterative transferred expert knowledge. We compare the performance of our algorithm to manual annotation by a specialist in mammography. Our results show that our parser's performance is comparable to the manual method.

  11. Tunability of the Quantum Spin Hall Effect in Bi(110) Films: Effects of Electric Field and Strain Engineering.

    Science.gov (United States)

    Li, Sheng-Shi; Ji, Wei-Xiao; Li, Ping; Hu, Shu-Jun; Cai, Li; Zhang, Chang-Wen; Yan, Shi-Shen

    2017-06-28

    The quantum spin Hall (QSH) effect is promising for achieving dissipationless transport devices due to their robust gapless edge states inside insulating bulk gap. However, the currently discussed QSH insulators usually suffer from ultrahigh vacuum or low temperature due to the small bulk gap, which limits their practical applications. Searching for large-gap QSH insulators is highly desirable. Here, the tunable QSH state of a Bi(110) films with a black phosphorus (BP) structure, which is robust against structural deformation and electric field, is explored by first-principles calculations. It is found that the two-monolayer BP-Bi(110) film obtains a tunable large bulk gap by strain engineering and its QSH effect shows a favorable robustness within a wide range of combinations of in-plane and out-of-plane strains, although a single in-plane compression or out-of-plane extension may restrict the topological phase due to the self-doping effect. More interestingly, in view of biaxial strain, two competing physics on band topology induced by bonding-antibonding and p x,y -p z band inversions are obtained. Meanwhile, the QSH effect can be persevered under an electric field of up to 0.9 V/Å. Moreover, with appropriate in-plane strain engineering, a nontrivial topological phase in a four-monolayer BP-Bi(110) film is identified. Our findings suggest that these two-dimensional BP-Bi(110) films are ideal platforms of the QSH effect for low-power dissipation devices.

  12. Luminescence of Bi3+ ions in Y3Al5O12:Bi single crystalline films

    International Nuclear Information System (INIS)

    Zorenko, Yu.; Gorbenko, V.; Voznyak, T.; Vistovsky, V.; Nedilko, S.; Nikl, M.

    2007-01-01

    The absorption and cathodoluminescence spectra of single crystalline films (SCF) of Y 3 Al 5 O 12 :Bi garnet depending on Bi concentration were analyzed. For consideration of the nature of the UV and visible Bi-related emission bands the time-resolved luminescence of Bi 3+ (ns 2 ) ions in YAG:Bi SCF was studied at 10 K under excitation by synchrotron radiation. The difference in the excitation spectra and emission decay of the UV and visible bands has been explained via radiative relaxation from the 3 P 1,0 excited states to the 1 S 0 ground state of the isolated and pair/clustered Bi 3+ emission centers in the garnet lattice, respectively

  13. The oxidation states of elements in pure and Ca-doped BiCuSeO thermoelectric oxides

    International Nuclear Information System (INIS)

    Hsiao, Chun-Lung; Qi, Xiaoding

    2016-01-01

    Bi 1−x Ca x CuSeO (x = 0–0.3) was synthesized at 650 °C in an air-tight system flowing with pure argon. The Ca doping resulted in an increase in the thermoelectric figure of merit (ZT) as the consequence of increased carrier concentration. X-ray photoelectron spectroscopy (XPS) was carried out to check the oxidation states in Bi 1−x Ca x CuSeO. The results indicated that in addition to the expected Bi 3+ and Cu 1+ , there existed Bi 2+ and Cu 2+ in the undoped BiCuSeO, whereas in the Ca-doped BiCuSeO, Bi 4+ , Cu 3+ and Cu 2+ were observed. The Ca dopant was confirmed to be in the 2+ oxidation state. Two broad peaks centered at 54.22 and 58.59 eV were recorded in the vicinity around the binding energy of Se 3d. The former is often observed in the Se-containing intermetallics while the latter is often found in the Se-containing oxides, indicating that along with the expected Se–Cu bonding, a bonding between Se and O may also exist. Based on the XPS results, the charge compensation mechanisms were proposed for Bi 1−x Ca x CuSeO, which may shed some light on the origins of charge carriers. BiCuSeO based oxides have recently be discovered to have a large ZT comparable to the best alloys currently in use, because of the large Seebeck coefficient and small thermal conductivity. However, their electrical conductivity is lower compared to the best thermoelectrics. This work may provide some hints for the further improvement of ZT in BiCuSeO based oxides. - Graphical abstract: The oxidation states, charge compensation mechanisms, and origins of charge carriers in Bi 1−x Ca x CuSeO thermoelectrics. Display Omitted

  14. A novel bi-protein bio-interphase of cytochrome c and glucose oxidase: Electron transfer and electrocatalysis

    International Nuclear Information System (INIS)

    Song, Yonghai; Liu, Hongyu; Wang, Yu; Wang, Li

    2013-01-01

    Graphical abstract: Glucose oxidase (GOD) and cytochrome c (Cyt c) were co-entrapped in the poly(diallyldimethylammonium chloride)–graphene nanosheets–gold nanoparticles (PDDA–Gp–AuNPs) nanocomposites modified glassy carbon electrode. Electron transfer and electrocatalysis of the novel bi-protein bio-interphase were investigated. The bio-interphase developed here not only successfully achieved DET of GOD, but also showed great potential for the fabrication of novel glucose biosensors with linear response up to 18 mM. Highlights: ► A bio-interphase composed of cytochrome c and glucose oxidase was developed. ► The electron transfer in the bio-interphase was investigated. ► Electrocatalytic performances of bio-interphase were explored. ► The bio-interphase exhibited good electrocatalytic response glucose. - Abstract: Glucose oxidase (GOD) and cytochrome c (Cyt c) were co-entrapped in the poly(diallyldimethylammonium chloride)–graphene nanosheets–gold nanoparticles (PDDA–Gp–AuNPs) hybrid nanocomposites modified glassy carbon electrode to prepare a novel bi-protein bio-interphase. Electron transfer and electrocatalysis of the bi-protein bio-interphase were investigated in detail. The results showed that the PDDA–Gp–AuNPs nanocomposites accelerated the electron transfer between proteins and electrode. The bi-protein exhibited effective direct electron transfer (DET) reaction with an apparent rate constant (k s ) of 2.36 s −1 . The optimal molar ratio and total amount of Cyt c and GOD in the bio-interphase for DET of GOD was estimated to be about 3:1 and 1.40 nmol, respectively. The bi-protein bio-interphase could be used to detect glucose based on the consumption of O 2 with the oxidation of glucose catalyzed by GOD. The resulted biosensor exhibits wide linear range from 2.0 to 18.0 mM. Thus, this study not only successfully achieved DET of GOD, but also constructed a novel biosensor for glucose detection

  15. High Gain and High Directive of Antenna Arrays Utilizing Dielectric Layer on Bismuth Titanate Ceramics

    Directory of Open Access Journals (Sweden)

    F. H. Wee

    2012-01-01

    Full Text Available A high gain and high directive microstrip patch array antenna formed from dielectric layer stacked on bismuth titanate (BiT ceramics have been investigated, fabricated, and measured. The antennas are designed and constructed with a combination of two-, four-, and six-BiT elements in an array form application on microwave substrate. For gain and directivity enhancement, a layer of dielectric was stacked on the BiT antenna array. We measured the gain and directivity of BiT array antennas with and without the dielectric layer and found that the gain of BiT array antenna with the dielectric layer was enhanced by about 1.4 dBi of directivity and 1.3 dB of gain over the one without the dielectric layer at 2.3 GHz. The impedance bandwidth of the BiT array antenna both with and without the dielectric layer is about 500 MHz and 350 MHz, respectively, which is suitable for the application of the WiMAX 2.3 GHz system. The utilization of BiT ceramics that covers about 90% of antenna led to high radiation efficiency, and small-size antennas were produced. In order to validate the proposed design, theoretical and measured results are provided and discussed.

  16. The crystal structure of Kirkiite, Pb10Bi3As3S19

    DEFF Research Database (Denmark)

    Makovicky, Emil; Balic Zunic, Tonci; Karanovic, Ljiljana

    2006-01-01

    and chemical analysis resulted in comparable formulae, Pb10Bi2.16As3.84S19 and Pb10.08Bi2.55Sb0.13As2.91S19, respectively, which are close to the ideal formula Pb10Bi3As3S19. The crystal lattice shows a pseudohexagonal symmetry, which is the cause of common twinning in this mineral. The main twin-law has (20...... layers parallel to (083) of kirkiite; the slabs are unit-cell-twinned on (010) refl ection planes. The structure contains one split As position, and two additional sites that could accommodate both As and Bi. The As,Bi distribution over these two sites is determined by the trapezoidal distortion...... of the half-octahedral coordination environment inside the tightly bonded double layers of the PbS-SnS archetype slabs. Owing to the stoichiometry requirements in this structure, Bi must also substitute for 1/11 of the Pb sites. Bond-valence calculations and the volumes of coordination polyhedra show...

  17. Thermal growth and cathodoluminescence of Bi doped ZnO nanowires and rods

    International Nuclear Information System (INIS)

    Aleman, B; Hidalgo, P; Fernandez, P; Piqueras, J

    2009-01-01

    Bi doped ZnO nanowires and rods have been grown by a catalyst free evaporation-deposition method with precursors containing either ZnO and Bi 2 O 3 or ZnS and Bi 2 O 3 powders. The use of ZnS as a precursor was found to lead to a higher density of nano- and microstructures at lower temperatures than by using ZnO. Energy dispersive x-ray spectroscopy (EDS) shows that the Bi content in the wires and rods is in the range 0.15-0.35 at%. Bi incorporation was found to induce a red shift of the near band gap luminescence but no quantitative correlation between the shift and the amount of Bi, as measured by EDS, was observed. The I-V curves of single Bi doped wires had linear behaviour at low current and non-linear behaviour for high currents, qualitatively similar to that of undoped wires.

  18. Thermal growth and cathodoluminescence of Bi doped ZnO nanowires and rods

    Energy Technology Data Exchange (ETDEWEB)

    Aleman, B; Hidalgo, P; Fernandez, P; Piqueras, J, E-mail: balemanl@fis.ucm.e [Departamento de Fisica de Materiales, Facultad de Ciencias FIsicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2009-11-21

    Bi doped ZnO nanowires and rods have been grown by a catalyst free evaporation-deposition method with precursors containing either ZnO and Bi{sub 2}O{sub 3} or ZnS and Bi{sub 2}O{sub 3} powders. The use of ZnS as a precursor was found to lead to a higher density of nano- and microstructures at lower temperatures than by using ZnO. Energy dispersive x-ray spectroscopy (EDS) shows that the Bi content in the wires and rods is in the range 0.15-0.35 at%. Bi incorporation was found to induce a red shift of the near band gap luminescence but no quantitative correlation between the shift and the amount of Bi, as measured by EDS, was observed. The I-V curves of single Bi doped wires had linear behaviour at low current and non-linear behaviour for high currents, qualitatively similar to that of undoped wires.

  19. Structural Flexibility of Large Direct Drive Generators for Wind Turbines

    NARCIS (Netherlands)

    Shrestha, G.

    2013-01-01

    The trend in wind energy is towards large offshore wind farms. This trend has led to the demand for high reliability and large single unit wind turbines. Different energy conversion topologies such as multiple stage geared generators, single stage geared generators and gearless (direct drive)

  20. Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface

    Science.gov (United States)

    Zhang, Haijun; Liu, Chao-Xing; Qi, Xiao-Liang; Dai, Xi; Fang, Zhong; Zhang, Shou-Cheng

    2009-06-01

    Topological insulators are new states of quantum matter in which surface states residing in the bulk insulating gap of such systems are protected by time-reversal symmetry. The study of such states was originally inspired by the robustness to scattering of conducting edge states in quantum Hall systems. Recently, such analogies have resulted in the discovery of topologically protected states in two-dimensional and three-dimensional band insulators with large spin-orbit coupling. So far, the only known three-dimensional topological insulator is BixSb1-x, which is an alloy with complex surface states. Here, we present the results of first-principles electronic structure calculations of the layered, stoichiometric crystals Sb2Te3, Sb2Se3, Bi2Te3 and Bi2Se3. Our calculations predict that Sb2Te3, Bi2Te3 and Bi2Se3 are topological insulators, whereas Sb2Se3 is not. These topological insulators have robust and simple surface states consisting of a single Dirac cone at the Γ point. In addition, we predict that Bi2Se3 has a topologically non-trivial energy gap of 0.3eV, which is larger than the energy scale of room temperature. We further present a simple and unified continuum model that captures the salient topological features of this class of materials.

  1. Decay studies of a long lived high spin isomer of 210Bi

    International Nuclear Information System (INIS)

    Tuggle, D.G.

    1976-08-01

    A source of approximately 30 μg of pure (> 90%) /sup 210m/Bi (Jπ = 9-) was prepared by irradiating 209 Bi in a nuclear reactor. After chemical separations to remove 210 Po from the irradiated bismuth sample were completed, the 210 Bi was electromagnetically separated from the 209 Bi by a series of two isotope separations to create the source mentioned above. This source was then used to conduct alpha, conversion electron, gamma, gamma-gamma coincidence, and alpha-gamma coincidence spectroscopic studies of the decay of /sup 210m/Bi. The partial half life for the alpha decay of /sup 210m/Bi was measured as 3.0 x 10 6 yr. A lower limit of 10 13 years was set for the partial half life for the decay of /sup 210m/Bi to 210 Po. Alpha decay of /sup 210m/Bi to 8 excited states of 206 Tl was observed. A lower limit of 10 -4 % was set for the branching ratio of the parity forbidden alpha decay of 210 Bi to the 206 Ti ground state. Theoretical decay rates for the alpha decays of /sup 210m/Bi, 210 Bi, 211 Po, and /sup 211m/Po were calculated using the method developed by Hans Mang. A comparison of the calculated and experimentally measured alpha decay rates of /sup 210m/Bi showed good agreement for the relative alpha decay rates

  2. CFD Simulations of Pb-Bi Two-Phase Flow

    International Nuclear Information System (INIS)

    Dostal, Vaclav; Zelezny, Vaclav; Zacha, Pavel

    2008-01-01

    In a Pb-Bi cooled direct contact steam generation fast reactor water is injected directly above the core, the produced steam is separated at the top and is send to the turbine. Neither the direct contact phenomenon nor the two-phase flow simulations in CFD have been thoroughly described yet. A first attempt in simulating such two-phase flow in 2D using the CFD code Fluent is presented in this paper. The volume of fluid explicit model was used. Other important simulation parameters were: pressure velocity relation PISO, discretization scheme body force weighted for pressure, second order upwind for momentum and CISCAM for void fraction. Boundary conditions were mass flow inlet (Pb-Bi 0 kg/s and steam 0.07 kg/s) and pressure outlet. The effect of mesh size (0.5 mm and 0.2 mm cells) was investigated as well as the effect of the turbulent model. It was found that using a fine mesh is very important in order to achieve larger bubbles and the turbulent model (k-ε realizable) is necessary to properly model the slug flow. The fine mesh and unsteady conditions resulted in computationally intense problem. This may pose difficulties in 3D simulations of the real experiments. (authors)

  3. Symmetry analysis of strain, electric and magnetic fields in the Bi2Se3-class of topological insulators

    Science.gov (United States)

    Rosdahl Brems, Mathias; Paaske, Jens; Lunde, Anders Mathias; Willatzen, Morten

    2018-05-01

    Based on group theoretical arguments we derive the most general Hamiltonian for the Bi2Se3-class of materials including terms to third order in the wave vector, first order in electric and magnetic fields, first order in strain and first order in both strain and wave vector. We determine analytically the effects of strain on the electronic structure of Bi2Se3. For the most experimentally relevant surface termination we analytically derive the surface state (SS) spectrum, revealing an anisotropic Dirac cone with elliptical constant energy contours giving rise to a direction-dependent group velocity. The spin-momentum locking of strained Bi2Se3 is shown to be modified. Hence, strain control can be used to manipulate the spin degree of freedom via the spin–orbit coupling. We show that for a thin film of Bi2Se3 the SS band gap induced by coupling between the opposite surfaces changes opposite to the bulk band gap under strain. Tuning the SS band gap by strain, gives new possibilities for the experimental investigation of the thickness dependent gap and optimization of optical properties relevant for, e.g., photodetector and energy harvesting applications. We finally derive analytical expressions for the effective mass tensor of the Bi2Se3 class of materials as a function of strain and electric field.

  4. Calorimetric investigation of (Pb0.45Bi0.55)-U system

    International Nuclear Information System (INIS)

    Agarwal, Renu; Samui, Pradeep; Mukerjee, S.K.; Ramakumar, K.L.

    2016-01-01

    Lead-bismuth eutectic (LBE) is being considered as a coolant of future high temperature reactors. As lead and bismuth are good spallation target material, they are planned to be used in accelerator driven reactor systems (ADS). Under the clad breach conditions these elements may come in direct contact with uranium of metallic fuel. In our labs, we had earlier investigated binary interactions of U-Pb and U-Bi. To assess interaction behaviour of 'U' with the eutectic melt, it was planned to measure enthalpy of mixing of LBE-U and compares it with the binary mixing. SEM-EDS studies of the product formed after mixing of LBE and 'U' were carried out to establish coexisting phases and their compositions. UPb 3 is Pb-rich compound of U-Pb and UBi 2 is Bi-rich compound of U-Bi. So addition of 'U' in (Pb 0.45 Bi 0.55 ) will result in formation of the more stable compound among UPb 3 and UBi 2

  5. Magnetic field induced superconductor-insulator transitions for ultra-thin Bi films on the different underlayers

    International Nuclear Information System (INIS)

    Makise, K; Kawaguti, T; Shinozaki, B

    2009-01-01

    This work shows the experimental results of the superconductor-insulator (S-I) transition for ultra-thin Bi films in magnetic fields. The quench-condensed (q-c) Bi film onto insulating underlayers have been interpreted to be homogeneous. In contrast, the Bi film without underlayers has been regarded as a granular film. The electrical transport properties of ultra-thin metal films near the S-I transition depend on the structure of the film. In order to confirm the effect of the underlayer to the homogeneity of the superconducting films, we investigate the characteristics of S-I transitions of q-c nominally homogeneous Bi films on underlayers of two insulating materials, SiO, and Sb. Under almost the same deposition condition except for the material of underlayer, we prepared the Bi films by repeating the additional deposition and performed in-situ electrical measurement. It is found that the transport properties near the S-I transitions show the remarkable difference between two films on different underlayers. As for Bi films on SiO, it turned out that the temperature dependence of resistance per square R sq (T) of the field-tuned transition and the thickness-tuned transition shows similar behavior; it was a thermally activated form. On the other hand, the R sq (T) of Bi films on Sb for thickness-tuned S-I transition showed logarithmic temperature dependence, but that for field-tuned S-I transition showed a thermally activated form.

  6. Ultrasonic study of structural instability of monocrystalline and polycrystalline Bi-Sr-Ca-Cu-O

    International Nuclear Information System (INIS)

    Wang, Yening; Wu, Jin; Shen, Huimin; Zhu, Jinsong; Chen, Xiaohua; Yan, Yifeng; Zhao, Zhongxian

    1990-01-01

    Two internal-friction (attenuation) peaks around 95 and 130 K in the polycrystal and single crystal of Bi-Sr-Ca-Cu-O are found to be related to the superconducting transition at 84 and 107 K, respectively. The jump of lattice parameter and shape-memory effect occurring at the peak temperatures reveal the characteristics of a martensitic transition. The velocity and attenuation versus temperature of ultrasonic longitudinal waves propagating along two directions in the a-b plane at 10 degree to the a and b axes and of [010] shear waves with [100] polarization were measured for the Bi 2 Sr 2 CaCu 2 O 8 single crystals. The anisotropic elasticity in the c plane is manifested. Only the longitudinal waves in a direction and the shear waves show an obvious softening minimum of velocity around 250 K, which is associated with an attenuation peak due to a phaselike transition, but other longitudinal waves reveal a monotonic stiffening from room temperature down to T c . The origin of the overall trend of elastic stiffening that appears in the measurements so far for high-T c oxides is discussed

  7. Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi 2 Se 3

    KAUST Repository

    Kong, Desheng

    2011-06-28

    Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi2Se3 gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi2Se3 nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi2Se3 under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi2Se3 by transport measurements. © 2011 American Chemical Society.

  8. Breast imaging reporting and data system (BI-RADS) lexicon for breast MRI: Interobserver variability in the description and assignment of BI-RADS category

    International Nuclear Information System (INIS)

    El Khoury, Mona; Lalonde, Lucie; David, Julie; Labelle, Maude; Mesurolle, Benoit; Trop, Isabelle

    2015-01-01

    Highlights: • The use of BI-RADS lexicon in interpreting breast MRI examinations is beneficial. • Our study shows: (a) moderate to substantial agreement between observers and (b) better agreement in interpreting mass than non-mass enhancement (NME). • Careful analysis of the NME should be done to help detect cancer as early as possible. - Abstract: Purpose: To retrospectively evaluate interobserver variability between breast radiologists when describing abnormal enhancement on breast MR examinations and assigning a BI-RADS category using the Breast Imaging Reporting and Data System (BI-RADS) terminology. Materials and methods: Five breast radiologists blinded to patients’ medical history and pathologic results retrospectively and independently reviewed 257 abnormal areas of enhancement on breast MRI performed in 173 women. Each radiologist described the focal enhancement using BI-RADS terminology and assigned a final BI-RADS category. Krippendorff's α coefficient of agreement was used to asses interobserver variability. Results: All radiologists agreed on the morphology of enhancement in 183/257 (71%) lesions, yielding a substantial agreement (Krippendorff's α = 0.71). Moderate agreement was obtained for mass descriptors – shape, margins and internal enhancement – (α = 0.55, 0.51 and 0.45 respectively) and NME (non-mass enhancement) descriptors – distribution and internal enhancement – (α = 0.54 and 0.43). Overall substantial agreement was obtained for BI-RADS category assignment (α = 0.71). It was however only moderate (α = 0.38) for NME compared to mass (α = 0.80). Conclusion: Our study shows good agreement in describing mass and NME on a breast MR examination but a better agreement in predicting malignancy for mass than NME

  9. Breast imaging reporting and data system (BI-RADS) lexicon for breast MRI: Interobserver variability in the description and assignment of BI-RADS category

    Energy Technology Data Exchange (ETDEWEB)

    El Khoury, Mona, E-mail: monelkhoury@gmail.com [Centre Hospitalier Universitaire de Montréal, Breast Centre, Radiology Department,