WorldWideScience

Sample records for vhf electrical properties

  1. A system for mapping sources of VHF and electric field pulses from in-cloud lightning at KSC

    Science.gov (United States)

    Thomson, Ewen M.; Medelius, Pedro J.

    1991-01-01

    The literature concerning VHF radiation and wideband electric fields from in-cloud lightning is reviewed. VHF location systems give impressive radio images of lightning in clouds with high spatial and temporal resolution. Using systems based on long and short baseline time-or-arrival and interferometry, workers have detected VHF sources that move at speeds of 10(exp 5) to 10(exp 8) m/s. The more slowly moving sources appear to be associated with channel formation but the physical basis for the higher speeds is not clear. In contrast, wideband electric fields are directly related to physical parameters such as current and tortuosity. A long baseline system is described to measure simultaneously VHF radiation and wideband electric fields at five stations at Kennedy Space Center. All signals are detected over remote, isolated ground planes with fiber optics for data transmission. The modification of this system to map rapidly varying dE/dt pulses is discussed.

  2. Final environmental assessment for vegetation control at VHF stations, microwave stations, electrical substations, and pole yards

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-10-13

    Southwestern Power Adm. operates very high frequency (VHF) and microwave radio stations, electrical substations, and pole yards for electric power transmission throughout AR, MO, and OK. Vegetation growth at the stations must be suppressed for safety of operation and personnel. Southwestern has been using a combination of mechanical/manual and herbicide control for this purpose; Federally- mandated reductions in staff and budgetary resources require Southwestern to evaluate all potentially efficient methods for vegetation control. Three alternatives were examined: no action, mechanical/manual control, and (proposed) a combination of mechanical/manual and herbicide control. Environmental impacts on air and water quality, wetlands, wildlife, endangered species, archaeological and other resources, farmland, human health, transportation, etc. were evaluated.

  3. Structure, optical properties and thermal stability of HfErO films deposited by simultaneous RF and VHF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H.Y. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Nanjing University of Posts and Telecommunications, School of Tongda, Nanjing (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); He, H.J.; Zhang, Z.; Jin, C.G.; Yang, Y.; Wang, Y.Y.; Ye, C. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Zhuge, L.J. [Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Soochow University, Analysis and Testing Center, Suzhou (China); Wu, X.M. [Soochow University, College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Suzhou (China); Soochow University, Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Suzhou (China); Chinese Academy of Sciences, State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Shanghai (China)

    2015-01-23

    HfErO films are deposited on Si substrates by simultaneous radio frequency (RF) and very high frequency (VHF) magnetron sputtering technique. The content of the doped ingredient of Er and the body composition of HfO{sub x} are, respectively, controlled through the VHF and RF powers. Low content of Er doping in the HfErO films can be achieved, because the VHF source of 27.12 MHz has higher ion energy and lower ion flux than the RF source resulting in low sputtering rate in the magnetron sputtering system. The structure, optical properties and thermal stability of the HfErO films are investigated in this work. Results show that the doped content of Er is independently controlled by the VHF power. The oxygen vacancies are created by the Er incorporation. The hafnium in the HfErO films forms mixed valence of Hf{sup 2+} and Hf{sup 4+}. The HfErO films are composed with the structures of HfO{sub 2}, HfO and ErO{sub x}, which can be optimized through the VHF power. At high VHF power, the Hf-Er-O bonds are formed, which demonstrates that the Er atoms are doped into the lattice of HfO{sub 2} in the HfErO films. The HfErO films have bad thermal stability as the crystallization temperature decreases from 900 to 800 C. After thermal annealing, cubic phase of HfO{sub 2} are stabilized, which is ascribed to the oxygen vacancies creation by the Er incorporation. The optical properties such as the refractive index and the optical band gap of the HfErO films are optimized by the VHF power. (orig.)

  4. Electrical properties of materials

    CERN Document Server

    Solymar, L; Syms, R R A

    2014-01-01

    An informal and highly accessible writing style, a simple treatment of mathematics, and clear guide to applications have made this book a classic text in electrical and electronic engineering. Students will find it both readable and comprehensive. The fundamental ideas relevant to the understanding of the electrical properties of materials are emphasized; in addition, topics are selected in order to explain the operation of devices having applications (or possible future applications) in engineering. The mathematics, kept deliberately to a minimum, is well within the grasp of a second-year student. This is achieved by choosing the simplest model that can display the essential properties of a phenomenom, and then examining the difference between the ideal and the actual behaviour. The whole text is designed as an undergraduate course. However most individual sections are self contained and can be used as background reading in graduate courses, and for interested persons who want to explore advances in microele...

  5. Electrical Properties of Sunflower Achenes

    Directory of Open Access Journals (Sweden)

    Novák Ján

    2014-12-01

    Full Text Available This work contains the results of measuring the electrical properties of sunflower achenes. The interest in electrical properties of biological materials resulted in engineering research in this field. The results of measurements are used for determining the moisture content, the surface level of liquid and grainy materials, for controlling the presence of pests in grain storage, for the quantitative determination of mechanical damage, in the application of dielectric heating, and in many other areas. Electrical measurements of these materials are of fundamental importance in relation to the analysis of quantity of absorbed water and dielectric heating characteristics. It is a well-known fact that electrical properties of materials, namely dielectric constant and conductivity, are affected by the moisture content of material. This fact is important for the design of many commercial moisturetesting instruments for agricultural products. The knowledge of dielectric properties of materials is necessary for the application of dielectric heating. The aim of this work was to measure conductivity, dielectric constant and loss tangent on samples of sunflower achenes, the electrical properties of which had not been sufficiently measured. Measurements were performed under variable moisture content and the frequency of electric field ranging from 1 MHz to 16 MHz, using a Q meter with coaxial probe. It was concluded that conductivity, dielectric constant and loss tangent increased with increasing moisture content, and dielectric constant and loss tangent decreased as the frequency of electric field increased.

  6. Dicty_cDB: VHF264 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF264 (Link to dictyBase) - - - Contig-U16260-1 VHF264P (Link to Original site) VHF...264F 606 VHF264Z 693 VHF264P 1279 - - Show VHF264 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-C/VHF264Q.Seq.d/ Representative seq. ID VHF...264P (Link to Original site) Representative DNA sequence >VHF264 (VHF264Q) /CSM/VH/VHF2-C/VHF...DRRKNIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHFEMPKEDKLPAGCTS

  7. Dicty_cDB: VHF181 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF181 (Link to dictyBase) - - - Contig-U16260-1 VHF181P (Link to Original site) VHF...181F 610 VHF181Z 416 VHF181P 1006 - - Show VHF181 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-D/VHF181Q.Seq.d/ Representative seq. ID VHF...181P (Link to Original site) Representative DNA sequence >VHF181 (VHF181Q) /CSM/VH/VHF1-D/VHF...VKYKMVNFTIDQIRAIMDRRENIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKVSG DMRYMSCRADEQERGITIKSSSVSLHF

  8. Dicty_cDB: VHF777 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF777 (Link to dictyBase) - - - Contig-U16283-1 VHF777P (Link to Original site) VHF...777F 474 VHF777Z 669 VHF777P 1123 - - Show VHF777 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF7-D/VHF777Q.Seq.d/ Representative seq. ID VHF...777P (Link to Original site) Representative DNA sequence >VHF777 (VHF777Q) /CSM/VH/VHF7-D/VHF...PNIIGVEHYKVATDVQKILXRI*itsryychfryg*fi *rpksncipcs*dstflittirscprxhqygr*ir*tlrlyq

  9. Dicty_cDB: VHF354 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF354 (Link to dictyBase) - - - Contig-U16260-1 VHF354P (Link to Original site) VHF...354F 617 VHF354Z 721 VHF354P 1318 - - Show VHF354 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-C/VHF354Q.Seq.d/ Representative seq. ID VHF...354P (Link to Original site) Representative DNA sequence >VHF354 (VHF354Q) /CSM/VH/VHF3-C/VHF...no Acid sequence LSSAKKVKYKMVNFTIDQIRAIMDRRENIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKV SGD

  10. Dicty_cDB: VHF590 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF590 (Link to dictyBase) - - - Contig-U16306-1 VHF590P (Link to Original site) VHF...590F 115 VHF590Z 603 VHF590P 698 - - Show VHF590 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF5-D/VHF590Q.Seq.d/ Representative seq. ID VHF...590P (Link to Original site) Representative DNA sequence >VHF590 (VHF590Q) /CSM/VH/VHF5-D/VHF5...qlphvlrqlk*sqnfhkkylkkvqeqqq--- ---rwifhrwccfqsthdamyflyqxfgslsw*snlxrpkist*xfyhifghfw*rls*l ss*ipi*lqkwysyv

  11. Dicty_cDB: VHF536 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF536 (Link to dictyBase) - - - Contig-U16531-1 VHF536P (Link to Original site) VHF...536F 255 VHF536Z 685 VHF536P 920 - - Show VHF536 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF5-B/VHF536Q.Seq.d/ Representative seq. ID VHF...536P (Link to Original site) Representative DNA sequence >VHF536 (VHF536Q) /CSM/VH/VHF5-B/VHF5...ti*mlhliskvmtvh*mslslfyggyfl*lsi*llwnysig qvvvcliksikxerllkstmt--- ---*erlcl*ilxlvsichf

  12. Dicty_cDB: VHF730 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF730 (Link to dictyBase) - - - Contig-U15767-1 VHF730P (Link to Original site) VHF...730F 569 VHF730Z 718 VHF730P 1267 - - Show VHF730 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF7-B/VHF730Q.Seq.d/ Representative seq. ID VHF...730P (Link to Original site) Representative DNA sequence >VHF730 (VHF730Q) /CSM/VH/VHF7-B/VHF...QEKRIPVLNSMDANDSINKKA RISWPDGFKYFFVDNQAGDSESAKSGKNLPIQRDIELNWNGEAYEYSNSNYFPINGQXFN DVSYPV--- ---lhvvvvkxvhtlpvnvnqivhf

  13. Dicty_cDB: VHF649 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF649 (Link to dictyBase) - - - Contig-U11031-1 VHF649P (Link to Original site) VHF...649F 562 VHF649Z 671 VHF649P 1213 - - Show VHF649 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF6-C/VHF649Q.Seq.d/ Representative seq. ID VHF...649P (Link to Original site) Representative DNA sequence >VHF649 (VHF649Q) /CSM/VH/VHF6-C/VHF...PNTPPTIKIELPSQSILKPSGQLKK*x* Translated Amino Acid sequence (All Frames) Frame A: i*qlvchlsivlfhhqviyphvlklekhf

  14. Dicty_cDB: VHF527 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF527 (Link to dictyBase) - - - Contig-U16260-1 VHF527P (Link to Original site) VHF...527F 571 VHF527Z 456 VHF527P 1007 - - Show VHF527 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF5-B/VHF527Q.Seq.d/ Representative seq. ID VHF...527P (Link to Original site) Representative DNA sequence >VHF527 (VHF527Q) /CSM/VH/VHF5-B/VHF...AKKVKYKMVNFTIDQIRAIMDRRENIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQXRGITIKSSSVSLHF

  15. Dicty_cDB: VHF294 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF294 (Link to dictyBase) - - - Contig-U16441-1 VHF294P (Link to Original site) VHF...294F 573 VHF294Z 215 VHF294P 768 - - Show VHF294 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-D/VHF294Q.Seq.d/ Representative seq. ID VHF...294P (Link to Original site) Representative DNA sequence >VHF294 (VHF294Q) /CSM/VH/VHF2-D/VHF2...ssfst*scisfttfry*gfsdctfr*fhfn**RFWFNMEQCII QWVMFYS--- ---DCHVSIKKFFKWWQRLDRWCCXXXSCXXXSWWFWFPTFLRIQISNXXY*k

  16. Dicty_cDB: VHF690 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF690 (Link to dictyBase) - - - Contig-U11064-1 VHF690P (Link to Original site) VHF...690F 199 VHF690Z 419 VHF690P 598 - - Show VHF690 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF6-D/VHF690Q.Seq.d/ Representative seq. ID VHF...690P (Link to Original site) Representative DNA sequence >VHF690 (VHF690Q) /CSM/VH/VHF6-D/VHF6...vllksqsknqyl*hlikslidfinif*hgmhqiyhqrkkn*nq *k--- ---rrwfpr*rernhhfqlc*sts*rgcryw

  17. Dicty_cDB: VHF273 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF273 (Link to dictyBase) - - - Contig-U11514-1 VHF273P (Link to Original site) VHF...273F 644 VHF273Z 678 VHF273P 1302 - - Show VHF273 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-D/VHF273Q.Seq.d/ Representative seq. ID VHF...273P (Link to Original site) Representative DNA sequence >VHF273 (VHF273Q) /CSM/VH/VHF2-D/VHF...ctr*ccnvkdwchyssrl*syrs*ts*nrsifidr*iftsh*kdw**s llwfsnetr*skmcchcnwckhflwscckfstrnrrtwssssys*kywslly*fhrhlg

  18. Dicty_cDB: VHF243 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF243 (Link to dictyBase) - - - Contig-U16423-1 VHF243P (Link to Original site) VHF...243F 580 VHF243Z 334 VHF243P 894 - - Show VHF243 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-B/VHF243Q.Seq.d/ Representative seq. ID VHF...243P (Link to Original site) Representative DNA sequence >VHF243 (VHF243Q) /CSM/VH/VHF2-B/VHF2...AATCNAGATATTCCAGATTGGTTTGAAAAGATGG TACA sequence update 2002.10.25 Translated Amino Acid sequence ifihadkff*RISHF

  19. Dicty_cDB: VHF134 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF134 (Link to dictyBase) - - - Contig-U16260-1 VHF134P (Link to Original site) VHF...134F 533 VHF134Z 404 VHF134P 917 - - Show VHF134 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-B/VHF134Q.Seq.d/ Representative seq. ID VHF...134P (Link to Original site) Representative DNA sequence >VHF134 (VHF134Q) /CSM/VH/VHF1-B/VHF1...cid sequence LSSAKKVKYKMVNFTIDQIRAIMDRRENIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHFEMPKE

  20. Dicty_cDB: VHF892 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF892 (Link to dictyBase) - - - Contig-U16260-1 VHF892P (Link to Original site) VHF...892F 140 VHF892Z 417 VHF892P 537 - - Show VHF892 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF8-D/VHF892Q.Seq.d/ Representative seq. ID VHF...892P (Link to Original site) Representative DNA sequence >VHF892 (VHF892Q) /CSM/VH/VHF8-D/VHF8... Translated Amino Acid sequence TIKSSSVSLHFEMPXEDKLPAGCTSHEFLINLIDSPSHVDFS--- ---ELTASPNILEPIYLVEITAPENAIGGI

  1. Dicty_cDB: VHF479 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF479 (Link to dictyBase) - - - Contig-U11426-1 VHF479P (Link to Original site) VHF...479F 629 VHF479Z 691 VHF479P 1300 - - Show VHF479 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-D/VHF479Q.Seq.d/ Representative seq. ID VHF...479P (Link to Original site) Representative DNA sequence >VHF479 (VHF479Q) /CSM/VH/VHF4-D/VHF...EKNPQEWRWSGGFFVDSISDYVVKSRNTERPDHDSLLF HVNIKEKQGTHFIRIPLSSKESPPYIIQNDTQFKISFFQRDSPENIDYIEPKEKLCYGWD EPSAEYVL

  2. Dicty_cDB: VHF754 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF754 (Link to dictyBase) - - - Contig-U16531-1 VHF754P (Link to Original site) VHF...754F 526 VHF754Z 624 VHF754P 1130 - - Show VHF754 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF7-C/VHF754Q.Seq.d/ Representative seq. ID VHF...754P (Link to Original site) Representative DNA sequence >VHF754 (VHF754Q) /CSM/VH/VHF7-C/VHF...ixnkmqwlkmlqvk*killk*ekvvslgiiftipf--- ---flvsichfnchc*itfccsrwnnlxllxfldsryllqw*

  3. Dicty_cDB: VHF461 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF461 (Link to dictyBase) - - - Contig-U11551-1 VHF461P (Link to Original site) VHF...461F 646 VHF461Z 261 VHF461P 887 - - Show VHF461 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-C/VHF461Q.Seq.d/ Representative seq. ID VHF...461P (Link to Original site) Representative DNA sequence >VHF461 (VHF461Q) /CSM/VH/VHF4-C/VHF4...TTAAATTATTAAAAATAGTAAATAAAAAAAA sequence update 2002.10.25 Translated Amino Acid sequence fyfifenfkthfhiiffl

  4. Dicty_cDB: VHF781 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF781 (Link to dictyBase) - - - Contig-U16440-1 VHF781P (Link to Original site) VHF...781F 452 VHF781Z 680 VHF781P 1112 - - Show VHF781 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF7-D/VHF781Q.Seq.d/ Representative seq. ID VHF...781P (Link to Original site) Representative DNA sequence >VHF781 (VHF781Q) /CSM/VH/VHF7-D/VHF...vlkmmmlkf*xixftr*r Frame C: glldinkleeiik*rfhlfylfl*rlllayhfhkilfqlisktaligsnfnhyiqikmim y*l*iqdqrmf*kdqqmvv

  5. Dicty_cDB: VHF435 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF435 (Link to dictyBase) - - - Contig-U16260-1 VHF435P (Link to Original site) VHF...435F 616 VHF435Z 703 VHF435P 1299 - - Show VHF435 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF4-B/VHF435Q.Seq.d/ Representative seq. ID VHF...435P (Link to Original site) Representative DNA sequence >VHF435 (VHF435Q) /CSM/VH/VHF4-B/VHF...AKKVKYKMVNFTIDQIRAIMDRRENIRNMSVIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHF

  6. Dicty_cDB: VHF553 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF553 (Link to dictyBase) - - - Contig-U16433-1 VHF553P (Link to Original site) VHF...553F 122 VHF553Z 533 VHF553P 635 - - Show VHF553 Library VH (Link to library) Clone ID VHF... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF5-C/VHF553Q.Seq.d/ Representative seq. ID VHF...553P (Link to Original site) Representative DNA sequence >VHF553 (VHF553Q) /CSM/VH/VHF5-C/VHF5...ed Amino Acid sequence syhfylfiy*IIIYLLNYYLLSCVNYLPINFNILYIY--- ---YVINLTLDGDNVNGFPKTVTVKPAPSXEQXYAEGEGLVKVF

  7. Dicty_cDB: VHF163 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF163 (Link to dictyBase) - - - Contig-U11129-1 VHF163P (Link to Original site) VHF1...63F 611 VHF163Z 654 VHF163P 1245 - - Show VHF163 Library VH (Link to library) Clone ID VHF1...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-C/VHF163Q.Seq.d/ Representative seq. ID VHF1...63P (Link to Original site) Representative DNA sequence >VHF163 (VHF163Q) /CSM/VH/VHF1-C/VHF1...nt alignments: (bits) Value VHF163 (VHF163Q) /CSM/VH/VHF1-C/VHF163Q.Seq.d/ 2357 0.0 VHM584 (VHM584Q) /CSM/VH

  8. Dicty_cDB: VHF444 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available (Link to library) VHF444 (Link to dictyBase) - G20601 DDB0204337 Contig-U12392-1 VHF444P (Link to Original...site) VHF444F 579 VHF444Z 213 VHF444P 772 - - Show VHF444 Library VH (Link to library) Clone ID VHF444 (Link...tsukuba.ac.jp/CSM/VH/VHF4-B/VHF444Q.Seq.d/ Representative seq. ID VHF444P (Link to Original site) Representative...Representative DNA sequence >VHF444 (VHF444Q) /CSM/VH/VHF4-B/VHF444Q.Seq.d/ CAAAAGAAATAAATAATTATGCCATCA...significant alignments: (bits) Value VHF444 (VHF444Q) /CSM/VH/VHF4-B/VHF444Q.Seq.d/ 1479 0.0 VHA836 (VHA836Q)

  9. Dicty_cDB: VHF338 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF338 (Link to dictyBase) - - - Contig-U14303-1 VHF338P (Link to Original site) VHF3...38F 208 VHF338Z 685 VHF338P 873 - - Show VHF338 Library VH (Link to library) Clone ID VHF3... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-B/VHF338Q.Seq.d/ Representative seq. ID VHF3...38P (Link to Original site) Representative DNA sequence >VHF338 (VHF338Q) /CSM/VH/VHF3-B/VHF3...significant alignments: (bits) Value VHF338 (VHF338Q) /CSM/VH/VHF3-B/VHF338Q.Seq.d/ 1296 0.0 VHK267 (VHK267Q

  10. Dicty_cDB: VHF394 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF394 (Link to dictyBase) - - - Contig-U16260-1 VHF394P (Link to Original site) VHF3...94F 563 VHF394Z 417 VHF394P 960 - - Show VHF394 Library VH (Link to library) Clone ID VHF3... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-D/VHF394Q.Seq.d/ Representative seq. ID VHF3...94P (Link to Original site) Representative DNA sequence >VHF394 (VHF394Q) /CSM/VH/VHF3-D/VHF3...nt alignments: (bits) Value VHF394 (VHF394Q) /CSM/VH/VHF3-D/VHF394Q.Seq.d/ 1776 0

  11. Dicty_cDB: VHF340 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF340 (Link to dictyBase) - - - Contig-U11939-1 VHF340P (Link to Original site) VHF3...40F 113 VHF340Z 506 VHF340P 599 - - Show VHF340 Library VH (Link to library) Clone ID VHF3... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-B/VHF340Q.Seq.d/ Representative seq. ID VHF3...40P (Link to Original site) Representative DNA sequence >VHF340 (VHF340Q) /CSM/VH/VHF3-B/VHF3...Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF340 (VHF340Q) /CSM/VH/VHF3-B/VHF3

  12. Dicty_cDB: VHF329 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF329 (Link to dictyBase) - - - Contig-U16260-1 VHF329P (Link to Original site) VHF3...29F 618 VHF329Z 633 VHF329P 1231 - - Show VHF329 Library VH (Link to library) Clone ID VHF3...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-B/VHF329Q.Seq.d/ Representative seq. ID VHF3...29P (Link to Original site) Representative DNA sequence >VHF329 (VHF329Q) /CSM/VH/VHF3-B/VHF3...s CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF329 (VHF329Q) /CSM/VH/VHF3

  13. Dicty_cDB: VHF187 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF187 (Link to dictyBase) - - - Contig-U16363-1 VHF187P (Link to Original site) VHF1...87F 549 VHF187Z 707 VHF187P 1236 - - Show VHF187 Library VH (Link to library) Clone ID VHF1...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1-D/VHF187Q.Seq.d/ Representative seq. ID VHF1...87P (Link to Original site) Representative DNA sequence >VHF187 (VHF187Q) /CSM/VH/VHF1-D/VHF1...* Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF187 (VHF1

  14. Dicty_cDB: VHF368 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF368 (Link to dictyBase) - - - Contig-U12673-1 VHF368P (Link to Original site) VHF3...68F 597 VHF368Z 746 VHF368P 1323 - - Show VHF368 Library VH (Link to library) Clone ID VHF3...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-C/VHF368Q.Seq.d/ Representative seq. ID VHF3...68P (Link to Original site) Representative DNA sequence >VHF368 (VHF368Q) /CSM/VH/VHF3-C/VHF3...ikfpknkii*nki k*nkiky Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF368 (VHF3

  15. Dicty_cDB: VHF348 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF348 (Link to dictyBase) - - - Contig-U13926-1 VHF348P (Link to Original site) VHF3...48F 539 VHF348Z 473 VHF348P 992 - - Show VHF348 Library VH (Link to library) Clone ID VHF3... URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-B/VHF348Q.Seq.d/ Representative seq. ID VHF3...48P (Link to Original site) Representative DNA sequence >VHF348 (VHF348Q) /CSM/VH/VHF3-B/VHF3...ksxvlmliltck Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF3

  16. Dicty_cDB: VHF312 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF312 (Link to dictyBase) - - - Contig-U15897-1 VHF312P (Link to Original site) VHF3...12F 543 VHF312Z 483 VHF312P 1006 - - Show VHF312 Library VH (Link to library) Clone ID VHF3...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-A/VHF312Q.Seq.d/ Representative seq. ID VHF3...12P (Link to Original site) Representative DNA sequence >VHF312 (VHF312Q) /CSM/VH/VHF3-A/VHF3... 4.0 %: extracellular, including cell wall 4.0 %: plasma membrane 4.0 %: peroxisomal >> prediction for VHF31

  17. Dicty_cDB: VHF375 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF375 (Link to dictyBase) - - - Contig-U16260-1 VHF375P (Link to Original site) VHF3...75F 432 VHF375Z 670 VHF375P 1082 - - Show VHF375 Library VH (Link to library) Clone ID VHF3...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-D/VHF375Q.Seq.d/ Representative seq. ID VHF3...75P (Link to Original site) Representative DNA sequence >VHF375 (VHF375Q) /CSM/VH/VHF3-D/VHF3...pperekv*pqksqiltnstknskqfkshxsfqr*xsnlkk Homology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF3

  18. Dicty_cDB: VHF190 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available F0-ATPase putative regulatory protein IF1 (if1) mRNA, complete cds; nuclear gene for mitochondrial produc...VH (Link to library) VHF190 (Link to dictyBase) - - - Contig-U12594-1 - (Link to Original site) VHF1...90F 581 - - - - - - Show VHF190 Library VH (Link to library) Clone ID VHF190 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF1-D/VHF190Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF190 (VHF190Q) /CSM/VH/VHF1-D/VHF190Q.Seq.d/ ATTTTTCATTTTAAAAA

  19. Dicty_cDB: VHF331 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF331 (Link to dictyBase) - - - - - (Link to Original site) VHF3...31F 609 - - - - - - Show VHF331 Library VH (Link to library) Clone ID VHF331 (Link to dictyBase) Atlas ID... - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-B/VHF3...31Q.Seq.d/ Representative seq. ID - (Link to Original site) Representative DNA sequence >VHF3...31 (VHF331Q) /CSM/VH/VHF3-B/VHF331Q.Seq.d/ AACTCTCGAGTGCAAAAAAAGTAAAGTACAAAATGGTTAATTTCA

  20. Dicty_cDB: VHF709 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF709 (Link to dictyBase) - - - Contig-U15897-1 - (Link to Original site) - - VHF...709Z 602 - - - - Show VHF709 Library VH (Link to library) Clone ID VHF709 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF7-A/VHF709Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF709 (VHF709Q) /CSM/VH/VHF7-A/VHF709Q.Seq.d/ XXXXXXXXXXCGTCCAA...vestir Frame B: ---sknfttrsrlqlccsfnglxpr**rw*tnrqhyhg*cksiwsssfnlsryyw*yrcs ilpqiq*kwchhsnlpiw*wsflyhf

  1. Dicty_cDB: VHF236 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF236 (Link to dictyBase) - - - Contig-U14303-1 - (Link to Original site) - - VHF...236Z 611 - - - - Show VHF236 Library VH (Link to library) Clone ID VHF236 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF2-B/VHF236Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF236 (VHF236Q) /CSM/VH/VHF2-B/VHF236Q.Seq.d/ XXXXXXXXXXTGCCATT...VQKISQELKHLT*tfvsylvlk Frame B: ---plvicc*ninvlhfveilsxhglay*xhcfplvlv*fqilsrmiqs

  2. Dicty_cDB: VHF140 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF140 (Link to dictyBase) - - - Contig-U15309-1 - (Link to Original site) - - VHF...140Z 518 - - - - Show VHF140 Library VH (Link to library) Clone ID VHF140 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF1-B/VHF140Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF140 (VHF140Q) /CSM/VH/VHF1-B/VHF140Q.Seq.d/ XXXXXXXXXXCCGATAA...EDYINMQIKQLENSENSQELIQKLNEHLSEYKASVEEIKHNVQNN Frame C: ---iixvtlmlflqngilhfigviil

  3. Dicty_cDB: VHF507 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF507 (Link to dictyBase) - - - Contig-U11594-1 - (Link to Original site) - - VHF...507Z 541 - - - - Show VHF507 Library VH (Link to library) Clone ID VHF507 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF5-A/VHF507Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF507 (VHF507Q) /CSM/VH/VHF5-A/VHF507Q.Seq.d/ XXXXXXXXXXTACCAAT...nvhsmiwihvglxlvigx*sncfvttsfikst mmvllcstftmllkpsixwivvsmkkyf*clemnxhfw*sviki*knv

  4. Dicty_cDB: VHF321 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF321 (Link to dictyBase) - - - Contig-U16260-1 - (Link to Original site) VHF...321F 617 - - - - - - Show VHF321 Library VH (Link to library) Clone ID VHF321 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF3-A/VHF321Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF321 (VHF321Q) /CSM/VH/VHF3-A/VHF321Q.Seq.d/ AACTCTCGAGTGCAAAA...VIAHVDHGKTTLSDSLIQRAGIIADKV SGDMRYMSCRADEQERGITIKSSSVSLHFEMPKEDKLPAGCTSHEFLINLIDSPGHVDFS SEVTAALRVTDGALVVIDC

  5. Dicty_cDB: VHF866 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF866 (Link to dictyBase) - - - Contig-U16600-1 - (Link to Original site) - - VHF...866Z 388 - - - - Show VHF866 Library VH (Link to library) Clone ID VHF866 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF8-C/VHF866Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF866 (VHF866Q) /CSM/VH/VHF8-C/VHF866Q.Seq.d/ XXXXXXXXXXAAGCAGC...Frame C: ---qhnnifklafptiknftgvpmxfvmtnegdnlgnftvkthfakffstyyscgeaghh yfdsccn*y*qkqgckfhs*h*xkssrr*lcfxqnwfi

  6. Dicty_cDB: VHF155 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF155 (Link to dictyBase) - - - - VHF155P (Link to Original site) VHF155F 587 VHF1...55Z 643 VHF155P 1210 - - Show VHF155 Library VH (Link to library) Clone ID VHF155 (Link... to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF1...-C/VHF155Q.Seq.d/ Representative seq. ID VHF155P (Link to... Original site) Representative DNA sequence >VHF155 (VHF155Q) /CSM/VH/VHF1-C/VHF155Q.Seq.d/ ATTCTCGATACTGGAA

  7. Dicty_cDB: VHF392 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF392 (Link to dictyBase) - - - - VHF392P (Link to Original site) VHF392F 568 VHF3...92Z 375 VHF392P 923 - - Show VHF392 Library VH (Link to library) Clone ID VHF392 (Link ...to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3...-D/VHF392Q.Seq.d/ Representative seq. ID VHF392P (Link to ...Original site) Representative DNA sequence >VHF392 (VHF392Q) /CSM/VH/VHF3-D/VHF392Q.Seq.d/ AACTCTCGAGTGCAAAA

  8. Dicty_cDB: VHF366 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF366 (Link to dictyBase) - - - Contig-U12131-1 | Contig-U13633-1 VHF3...66P (Link to Original site) VHF366F 590 VHF366Z 544 VHF366P 1114 - - Show VHF366 Library VH (Link to library) Clone ID VHF3...131-1 | Contig-U13633-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-C/VHF3...66Q.Seq.d/ Representative seq. ID VHF366P (Link to Original site) Representative DNA sequence >VHF366 (VHF3...66Q) /CSM/VH/VHF3-C/VHF366Q.Seq.d/ AATAATTTATTATTATTATTAATAAGTAATAGAAATAAAAGATGGAACCAATTCCAGATA

  9. Dicty_cDB: VHF310 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF310 (Link to dictyBase) - - - Contig-U16260-1 - (Link to Original site) - - VHF3...10Z 625 - - - - Show VHF310 Library VH (Link to library) Clone ID VHF310 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF3-A/VHF310Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF310 (VHF310Q) /CSM/VH/VHF3-A/VHF310Q.Seq.d/ XXXXXXXXXXTCGTCAA...omology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value VHF310 (VHF310Q) /CSM/VH/VHF3-A/VHF3

  10. Dicty_cDB: VHF315 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF315 (Link to dictyBase) - G20600 DDB0169270 Contig-U12450-1 VHF3...15P (Link to Original site) VHF315F 216 VHF315Z 353 VHF315P 549 - - Show VHF315 Library VH (Link to library) Clone ID VHF3...ontig-U12450-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF3-A/VHF3...15Q.Seq.d/ Representative seq. ID VHF315P (Link to Original site) Representative DNA sequence >VHF315 (VHF315Q) /CSM/VH/VHF3...-A/VHF315Q.Seq.d/ ATTAAAAAACTTCTTACTTGGACACCCCTTTTATATATATAAATAAAAACTTCTAAATAT AAATCCCA

  11. Dicty_cDB: VHF381 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF381 (Link to dictyBase) - - - Contig-U16508-1 - (Link to Original site) - - VHF3...81Z 645 - - - - Show VHF381 Library VH (Link to library) Clone ID VHF381 (Link to dicty...iol.tsukuba.ac.jp/CSM/VH/VHF3-D/VHF381Q.Seq.d/ Representative seq. ID - (Link to ...Original site) Representative DNA sequence >VHF381 (VHF381Q) /CSM/VH/VHF3-D/VHF381Q.Seq.d/ XXXXXXXXXXCAACCAA...ignments: (bits) Value VHF381 (VHF381Q) /CSM/VH/VHF3-D/VHF381Q.Seq.d/ 1223 0.0 VHP767 (VHP767Q) /CSM/VH/VHP7

  12. Dicty_cDB: VHF210 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF210 (Link to dictyBase) - - - Contig-U12400-1 | Contig-U16431-1 VHF...210P (Link to Original site) VHF210F 613 VHF210Z 636 VHF210P 1229 - - Show VHF210 Library VH (Link to library) Clone ID VHF...400-1 | Contig-U16431-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-A/VHF...210Q.Seq.d/ Representative seq. ID VHF210P (Link to Original site) Representative DNA sequence >VHF210 (VHF...210Q) /CSM/VH/VHF2-A/VHF210Q.Seq.d/ AATAAAATGATAAGATCATCAATAAAAAATAAAATAACAACAACAAAAAGTTTATCATGT

  13. Dicty_cDB: VHF575 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF575 (Link to dictyBase) - - - Contig-U15481-1 | Contig-U15981-1 VHF...575P (Link to Original site) VHF575F 586 VHF575Z 397 VHF575P 963 - - Show VHF575 Library VH (Link to library) Clone ID VHF...81-1 | Contig-U15981-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF5-D/VHF...575Q.Seq.d/ Representative seq. ID VHF575P (Link to Original site) Representative DNA sequence >VHF575 (VHF...575Q) /CSM/VH/VHF5-D/VHF575Q.Seq.d/ ATAATAATACAAAGAAGAAATGAAAAATATAAATAATAAAATTTTAAAGATTTTTATTCT

  14. Dicty_cDB: VHF296 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF296 (Link to dictyBase) - G23392 DDB0187414 Contig-U12449-1 VHF...296P (Link to Original site) VHF296F 241 VHF296Z 482 VHF296P 703 - - Show VHF296 Library VH (Link to library) Clone ID VHF...ontig-U12449-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-D/VHF...296Q.Seq.d/ Representative seq. ID VHF296P (Link to Original site) Representative DNA sequence >VHF296 (VHF296Q) /CSM/VH/VHF...2-D/VHF296Q.Seq.d/ GATTATCAGAAAGATTACATTATGAAATTATACCAGATTGTATTAAAATTATTGAAAGCT CAAAACAA

  15. Dicty_cDB: VHF436 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF436 (Link to dictyBase) - - - - VHF436P (Link to Original site) VHF436F 618 VHF...436Z 699 VHF436P 1297 - - Show VHF436 Library VH (Link to library) Clone ID VHF436 (Link... to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF...4-B/VHF436Q.Seq.d/ Representative seq. ID VHF436P (Link to... Original site) Representative DNA sequence >VHF436 (VHF436Q) /CSM/VH/VHF4-B/VHF436Q.Seq.d/ AACTCTCGAGTGCAAA

  16. Dicty_cDB: VHF158 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF158 (Link to dictyBase) - - - - VHF158P (Link to Original site) VHF158F 608 VHF...158Z 693 VHF158P 1281 - - Show VHF158 Library VH (Link to library) Clone ID VHF158 (Link... to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig - Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF...1-C/VHF158Q.Seq.d/ Representative seq. ID VHF158P (Link to... Original site) Representative DNA sequence >VHF158 (VHF158Q) /CSM/VH/VHF1-C/VHF158Q.Seq.d/ AACTCTCGAGTGCAAA

  17. Dicty_cDB: VHF847 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF847 (Link to dictyBase) - - - Contig-U15351-1 | Contig-U16514-1 VHF...847P (Link to Original site) VHF847F 478 VHF847Z 709 VHF847P 1167 - - Show VHF847 Library VH (Link to library) Clone ID VHF...351-1 | Contig-U16514-1 Original site URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF8-B/VHF...847Q.Seq.d/ Representative seq. ID VHF847P (Link to Original site) Representative DNA sequence >VHF847 (VHF...847Q) /CSM/VH/VHF8-B/VHF847Q.Seq.d/ TATGATGTTCCACTTATAATTCAAACGGTTGCCAATAATAAATCAACAAAACTCANTCTT

  18. Dicty_cDB: VHF272 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF272 (Link to dictyBase) - - - Contig-U15754-1 VHF272P (Link to Original site) VHF...272F 515 VHF272Z 603 VHF272P 1098 - - Show VHF272 Library VH (Link to library) Clone ID VHF...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/VH/VHF2-C/VHF272Q.Seq.d/ Representative seq. ID VHF...272P (Link to Original site) Representative DNA sequence >VHF272 (VHF272Q) /CSM/VH/VHF2-C/VHF...id sequence (All Frames) Frame A: ixfssq**wnkkd*mihy*eiligrigvpm*vidngqlfvkimvvnhgptfhtimldhvh idgqrivlvdfvidfkifv*v*hf

  19. Monitoring forest soil properties with electrical resistivity

    OpenAIRE

    Paillet, Y.; Cassagne, N.; Brun, J.J.

    2010-01-01

    Maintenance and monitoring of soil fertility is a key issue for sustainable forest management. Vital ecosystem processes may be affected by management practices which change the physical, chemical and biological properties of the soil. This study is the first in Europe to use electrical resistivity as a non-invasive method to determine forest soil properties rapidly in the field in a monitoring purpose. We explored the correlations between electrical resistivity and forest soil properties on ...

  20. Magnetic and Electrical Properties of Leachate

    Directory of Open Access Journals (Sweden)

    Kartika Kirana

    2011-11-01

    Full Text Available Heavy metals content as well as magnetic and electrical properties of leachate from Sarimukti, West Java were studied in an attempt to seek correlation between heavy metals content and magnetic/electrical properties. Such correlation is expected to open the way for the use of magnetic/electrical properties as proxy indicators for the concentration of heavy metals in the leachate. The number of leachate samples studied is 21; 15 were taken spatially at depth of 1 m while the remaining 6 samples were taken vertically at a particular point. Measurement results showed that the heavy metals content in the leachate has a smaller concentration, except for Fe. The correlation between magnetic susceptibility and heavy metals content was found to be not so significant. The best correlation coefficient between magnetic susceptibility with heavy metals in leachate was found in Zn. Correlation between electrical conductivity and heavy metal is also not so significant, except for Zn and Cd. The use of magnetic properties as proxy indicator for heavy metals content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Correlation between magnetic susceptibility, electrical conductivity and heavy metal content would be good if each quantity has a large value.

  1. Structural, dielectric and electrical properties of ...

    Indian Academy of Sciences (India)

    by Jonscher's universal power law. Electrical transport properties of the material show ... modified Curie–Weiss law) is more than that of present compound. The temperature variation of polarization was ..... of the absence of one of the transverse (soft) modes, restoring force tends to zero at ferroelectric–paraelectric phase ...

  2. Structural, dielectric and electrical properties of ...

    Indian Academy of Sciences (India)

    Electrical properties of the material have been analyzed using complex impedance technique. The Nyquist plots manifest the contribution of grain boundaries (at higher temperature), in addition to granular contribution (at all temperatures) to the overall impedance. The temperature dependence of dc conductivity suggests ...

  3. [Research progress and prospect of electrical properties tomography for prostate].

    Science.gov (United States)

    Lin, Yang; Dai, Songshi; Zhu, Shan'an

    2012-10-01

    We reviewed the research progress and prospect of electrical properties tomography for prostate in this paper. After the introduction of the basic principles of electrical impedance tomography (EIT) and magnetic resonance electric impedance tomography (MREIT), we presented the applications of the two techniques in electrical properties tomography of the prostate in detail. We then discussed the application prospects of induced current magnetic resonance electric impedance tomography (IC-MREIT) and magnetic resonance electrical properties tomography (MREPT) in the diagnoses of prostate cancer.

  4. Electrical and magneto transport properties of

    Indian Academy of Sciences (India)

    Electrical and magneto transport properties of. La0.8−xCaxSr0.1Ag0.1MnO3 (x = 0.1,0.2,0.3). P SUBHASHINI1,∗, B MUNIRATHINAM2, M KRISHNAIAH1, R VENKATESH3,. D VENKATESWARLU3 and V GANESAN3. 1Department of Physics, Sri Venkateswara University, Tirupati, India. 2NDT/SPP, SDSC SHAR, Sriharikota ...

  5. Modification of electrical properties of topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Peter Anand

    2017-08-29

    Ion implantation or deposition can be used to modify the bulk electrical properties of topological insulators. More particularly, ion implantation or deposition can be used to compensate for the non-zero bulk conductivity due to extrinsic charge carriers. The direct implantation of deposition/annealing of dopants allows better control over carrier concentrations for the purposes of achieving low bulk conductivity. Ion implantation or deposition enables the fabrication of inhomogeneously doped structures, enabling new types of device designs.

  6. Electrical properties of polycrystalline methane hydrate

    Science.gov (United States)

    Du Frane, W. L.; Stern, L.A.; Weitemeyer, K.A.; Constable, S.; Pinkston, J.C.; Roberts, J.J.

    2011-01-01

    Electromagnetic (EM) remote-sensing techniques are demonstrated to be sensitive to gas hydrate concentration and distribution and complement other resource assessment techniques, particularly seismic methods. To fully utilize EM results requires knowledge of the electrical properties of individual phases and mixing relations, yet little is known about the electrical properties of gas hydrates. We developed a pressure cell to synthesize gas hydrate while simultaneously measuring in situ frequency-dependent electrical conductivity (σ). Synthesis of methane (CH4) hydrate was verified by thermal monitoring and by post run cryogenic scanning electron microscope imaging. Impedance spectra (20 Hz to 2 MHz) were collected before and after synthesis of polycrystalline CH4 hydrate from polycrystalline ice and used to calculate σ. We determined the σ of CH4 hydrate to be 5 × 10−5 S/m at 0°C with activation energy (Ea) of 30.6 kJ/mol (−15 to 15°C). After dissociation back into ice, σ measurements of samples increased by a factor of ~4 and Ea increased by ~50%, similar to the starting ice samples.

  7. Electrical properties of methane hydrate + sediment mixtures

    Science.gov (United States)

    Du Frane, Wyatt L.; Stern, Laura A.; Weitemeyer, Karen A.; Constable, Steven; Roberts, Jeffery J.

    2011-01-01

    As part of our DOE-funded proposal to characterize gas hydrate in the Gulf of Mexico using marine electromagnetic methods, a collaboration between SIO, LLNL, and USGS with the goal of measuring the electrical properties of lab-created methane (CH4) hydrate and sediment mixtures was formed. We examined samples with known characteristics to better relate electrical properties measured in the field to specific gas hydrate concentration and distribution patterns. Here we discuss first-ever electrical conductivity (σ) measurements on unmixed CH4 hydrate (Du Frane et al., 2011): 6 x 10-5 S/m at 5 °C, which is ~5 orders of magnitude lower than seawater. This difference allows electromagnetic (EM) techniques to distinguish highly resistive gas hydrate deposits from conductive water saturated sediments in EM field surveys. More recently, we performed measurements on CH4 hydrate mixed with sediment and we also discuss those initial findings here. Our results on samples free of liquid water are important for predicting conductivity of sediments with pores highly saturated with gas hydrate, and are an essential starting point for comprehensive mixing models.

  8. Anechoic chamber for VHF and UHF bands

    Science.gov (United States)

    Morikawa, Takao; Sugiura, Akira; Harima, Katsushige; Masuzawa, Hiroshi

    1995-06-01

    Built in 1969, the anechoic chamber of CRL has been used to the fullest by researchers in many fields such as EMI, EMC, antenna design, standard of electric field intensity, and type approval testing. In particular, in the early days of space development in Japan, many satellite-born antennas were developed in this anechoic chamber. However, a quarter of a century has passed since its construction and deteriorated performance due to superannuation sometimes caused difficulties in experiments conducted in the chamber. In 1993, CRL constructed a Measuring Facility for Radio Research (MFRR) and the anechoic chamber for VHF-UHF bands was remodeled as one of the sub-facilities of MFRR. The remodeling work included full replacement of the electromagnetic shielding, absorbers and measurement system. Since the remodeled anechoic chamber is being used not only for EMI tests but also for other purposes, a full-anechoic chamber has been adopted. In addition the chamber has been designed for the frequency range between 30 MHz and 10 GHz. After the remodeling work, the performance of the chamber is greatly improved. The average shielding factor is better than 85 dB for all frequency ranges and the unwanted reflection characteristic is -30 dB for frequencies above 1 GHZ. This paper summarizes the remodeling work, and the specifications and performance of the remodeled anechoic chamber.

  9. Crystal growth, electrical and photophysical properties of Tl2S ...

    Indian Academy of Sciences (India)

    871–885. Crystal growth, electrical and photophysical properties of Tl2S layered single crystals ... resultant crystals, the electrical properties (electrical conductivity and Hall effect) and steady-state photoconductivity were .... Block of wood, which was shaped in a triangle form. excessive heat loss, the temperature variation ...

  10. Design and Development of VHF Antennas for Space Borne Signal of Opportunity Receivers for Cubesat Platforms

    Science.gov (United States)

    Deshpande, Manohar; Piepmeier, Jeffrey

    2015-01-01

    Design and Development of VHF Antennas for Space Borne Signal of Opportunity Receivers for Cubesat Platforms. Space borne microwave remote sensors at VHF/UHF frequencies are important instruments to observe reflective properties of land surfaces through thick and heavy forestation on a global scale. One of the most cost effective ways of measuring land reflectivity at VHF/UHF frequencies is to use signals transmitted by existing communication satellites (operating at VHF/UHF band) as a signal of opportunity (SoOp) signal and passive receivers integrated with airborne/space borne platforms operating in the Low Earth Orbit (LEO). One of the critical components of the passive receiver is two antennas (one to receive only direct signal and other to receive only reflected signal) which need to have ideally high (>30dB) isolation. However, because of small size of host platforms and broad beam width of dipole antennas, achieving adequate isolation between two channels is a challenging problem and need to be solved for successful implementation of space borne SoOp technology for remote sensing. In this presentation a novel enabling VHF antenna technology for Cubesat platforms is presented to receive direct as well as reflected signal with needed isolation. The novel scheme also allows enhancing the gain of individual channels by factor of 2 without use of reflecting ground plane

  11. Electrical properties of nucleic acid bases

    Science.gov (United States)

    Basch, Harold; Garmer, D. R.; Jasien, P. G.; Krauss, M.; Stevens, W. J.

    1989-11-01

    The dipole polarizabilities for the five nucleic acid bases, uracil, cytosine, thymine, guanine, and adenine have been determined by the coupled perturbed Hartree-Fock (CPHF) method using a polarized double-zeta basis set. Electronic correlation corrections from second-order Møller-Plesset (MP2) perturbation theory are given. The treatment required to obtain accurate polarizabilities of these π systems was estimated from calculations on imidazole, benzene, and pyridine, giving results that are in good agreement with experiment. Similarly, optimal basis sets for static electrical properties were determined and applied to calculations of the dipole moments of the bases. With correlation corrections, these agree with experiment within 5% for all molecules except adenine.

  12. Dicty_cDB: VHF476 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available uences producing significant alignments: (bits) Value VHF476 (VHF476Q) /CSM/VH/VHF4-D/VHF476Q.Seq.d/ 198 2e-...46 own update 2003.10.17 Homology vs DNA Score E Sequences producing significant alignments: (bits) Value...e 2008.10.29 Homology vs Protein Score E Sequences producing significant alignments: (bits) Value (Q54AX5) R

  13. Electrical and magnetic properties of new copper arylcarboxylates

    Science.gov (United States)

    Cueto, Senida; Rys, Paul; Rys, Franz S.; Sanjinez, Rosendo; Peter Straumann, Hans

    1992-02-01

    The magnetic and electrical properties of new copper arylcarboxylates are presented. Special emphasis on copper(II) terephthalate trihydrate (CuTT) is given, and the magnetic and electrical properties are correlated with the crystal structure, recently determined by us. We have obtained new conductor materials by partial reduction of CuTT. The properties of these new compounds are discussed.

  14. Interrelationships between electrical, mechanical and hydration properties of cortical bone.

    Science.gov (United States)

    Unal, Mustafa; Cingoz, Fatih; Bagcioglu, Cevat; Sozer, Yilmaz; Akkus, Ozan

    2018-01-01

    Interrelationship between electrical and mechanical properties of cortical bone and the role of bone composition in this interrelationship are not comprehensively investigated to date. This study aimed to investigate associations of electrical properties (i.e., specific impedance, dielectric constant, and conductivity) with mechanical properties (i.e., toughness, strength and elastic modulus) of wet and sequentially dehydrated cortical bone. Bovine cortical bone samples (N = 24) were subjected to three-point bending test. A sequential heat treatment protocol ensued to tease out contributions of unbound water and bound water. Demineralization was performed to understand contributions of organic matrix and the mineral phase to the electrical properties of cortical bone. Raman-spectroscopy based water measurement was used to investigate involvement of collagen- and mineral-bound water in the electrical properties. Our results showed statistically significant correlations between electrical and mechanical properties of cortical bone. Toughness and ultimate strength were negatively correlated with impedance and positively correlated with conductivity and dielectric constant. The highest correlations between electrical and mechanical properties of cortical bone were typically found at the frequencies of 0.2, 0.5 and 1MHz. The electrical properties of bone changed significantly as a result of sequential dehydration, indicating that unbound and bound water compartments are the key determinants of the electrical properties. Comparison of porosity matched bone samples with high and low amount of bound water showed that bound water compartments may have an independent role in determining electrical properties of cortical bone. Furthermore, the results indicated that collagen and mineral-bound water may contribute differentially to the electrical properties of a bone. In the overall, our results suggest that electrical properties of cortical bone may be used to assess bone

  15. Innovative processing for improved electrical steel properties

    Directory of Open Access Journals (Sweden)

    Schneider, J.

    2010-10-01

    Full Text Available Electrical steel grades are the normal construction material for electrical motors and transformers because of their enhanced soft magnetic properties. One of the current trends in their production aims for increasing the silicon and/or aluminum concentration (above 3 wt % to reduce magnetic losses through increased electrical resistivity. This is very difficult to realize by conventional processing, mainly because of cracking during cold rolling. An alternative production route is proposed that raises the silicon and/or aluminum concentration by surface deposition of silicon and/or aluminum on a low-Si/low-Al steel substrate, e.g. by a short immersion in a molten Al-Si bath, followed by its diffusion into the bulk during subsequent annealing. This diffusion substantially modifies the microstructural features and therefore affects the mechanical and magnetic properties. Results of research efforts to optimize this production route and to understand the mechanisms and effects of the structural changes are presented and discussed.Los aceros eléctricos se usan, normalmente, en la construcción de motores eléctricos y transformadores debido a sus suaves propiedades magnéticas. Una de las tendencias actuales es producir aceros con contenidos mayores de silicio y/o aluminio (por encima de un 3 %, en peso para reducir las pérdidas magnéticas a través del incremento de la resistividad eléctrica. Una de las desventajas de producir este tipo de aceros con altos contenidos de silicio y/o aluminio es el agrietamiento producido en el material durante el proceso de laminado en frío. Para incrementar el contenido de silicio y/o aluminio en aceros con bajos contenidos de estos elementos de aleación, se sugiere un procedimiento alternativo de producción que se basa, fundamentalmente, en depositar un recubrimiento rico en silicio y/o aluminio, en la superficie del acero. Por ejemplo, uno de los métodos utilizados es sumergir el material en una aleaci

  16. Crystal growth, electrical and photophysical properties of Tl2S ...

    Indian Academy of Sciences (India)

    The Tl2S compound was prepared in a single crystal form using a special local technique, and the obtained crystals were analysed by X-ray diffraction. For the resultant crystals, the electrical properties (electrical conductivity and Hall effect) and steady-state photoconductivity were elucidated in this work. The electrical ...

  17. Effect of copper doping on structural, optical and electrical properties ...

    Indian Academy of Sciences (India)

    causing changes in the optical and electrical properties. XRD pattern also supports absence of CuS in the film, thereby less solubility product of CuS will not cause in the way of defect formation as the doping concentration is very low. 3.5 Electrical conductivity studies. Variation of electrical conductivity with temperature was.

  18. Effect of aluminum addition on electrical properties, dielectric ...

    Indian Academy of Sciences (India)

    Administrator

    varistor is a very smart electroceramic device, where the voltage–current properties are highly nonlinear. Pure zinc oxide ceramics exhibit linear properties even ..... tinuous normal electrical stress, lightning surge, and switching surge. Under such surges, they are gradually degraded with time. Therefore, the high electrical ...

  19. Electrical and optical properties of silicon-doped gallium nitride ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 31; Issue 1. Electrical and optical properties of silicon-doped gallium nitride polycrystalline films. S R Bhattacharyya A K Pal. Thin Films Volume ... Electrical, optical and microstructural properties were studied for these films. It was observed that films deposited at room ...

  20. Influence of Zn doping on electrical and optical properties of ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 29; Issue 3. Influence of Zn doping on electrical and optical properties of multilayered tin oxide thin films. J S Bhat K I ... In this study, the electrical and optical properties of Zn doped tin oxide films prepared using sol–gel spin coating process have been investigated.

  1. Method of determining an electrical property of a test sample

    DEFF Research Database (Denmark)

    2010-01-01

    A method of obtaining an electrical property of a test sample, comprising a non-conductive area and a conductive or semi-conductive test area, byperforming multiple measurements using a multi-point probe. The method comprising the steps of providing a magnetic field having field lines passing...... the electrical property of the test area....

  2. 47 CFR 80.911 - VHF transmitter.

    Science.gov (United States)

    2010-10-01

    ... MARITIME SERVICES Compulsory Radiotelephone Installations for Small Passenger Boats § 80.911 VHF..., measured at the power input terminals to the transmitter, and the output power of the transmitter, terminated in a matching artificial load, must be measured at the end of 10 minutes of continuous operation...

  3. Electrical properties of epoxy resin based nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Tuncer, Enis [High Voltage and Dielectrics, Applied Superconductivity Group, Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, TN 37832-6122 (United States); Sauers, Isidor [High Voltage and Dielectrics, Applied Superconductivity Group, Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, TN 37832-6122 (United States); James, D Randy [High Voltage and Dielectrics, Applied Superconductivity Group, Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, TN 37832-6122 (United States); Ellis, Alvin R [High Voltage and Dielectrics, Applied Superconductivity Group, Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, TN 37832-6122 (United States); Paranthaman, M Parans [Materials Chemistry Group, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37832-6122 (United States); Aytug, Tolga [Materials Chemistry Group, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37832-6122 (United States); Sathyamurthy, Srivatsan [Materials Chemistry Group, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37832-6122 (United States); More, Karren L [Microscopy Microanalysis and Microstructures Group, Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37832-6122 (United States); Li, Jing [Superconductive and Energy Efficient Materials Group, Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Goyal, Amit [Superconductive and Energy Efficient Materials Group, Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2007-01-17

    We investigate the electrical properties of composite materials prepared as nano- and sub-micron-scale metal-oxide particles embedded in a commercial resin. The filler particles are barium titanate and calcium copper titanate. The physical and structural characteristics of the constituents and the fabricated composites are reported. Electrical characterization of the composite samples is performed using time- and frequency-domain dielectric spectroscopy techniques. The electrical breakdown strength of samples with nano- and sub-micron-sized particles have better electrical insulation properties than the unfilled resin.

  4. Comparison between the electrical properties of polyphenylacetylene and polyaminotriazole

    Directory of Open Access Journals (Sweden)

    M. Yahia Abed

    2014-03-01

    Full Text Available The electrical properties of a polymer containing aromatic rings were compared with those of polyheterocyclic compound. Each segment of the polyheterocyclic compound contains three nitrogen atoms. Both polymers were prepared at the laboratory. It was found that the specific electrical conductivity of polyphenylacetylene is higher than that of polyaminotriazole. Log ρ vs. 103/T was traced for both compounds, where ρ is the specific electrical resistivity and T is the absolute temperature. Complexes of each compound with KI were prepared. The electrical properties of these complexes were studied. The microstructure of both compounds was determined by FTIR spectroscopy.

  5. Thermal and Electrical Properties of Electrides

    Science.gov (United States)

    Moeggenborg, Kevin James

    1990-01-01

    A method to determine the stability and decomposition kinetics of electrides was developed. The method uses DSC and was applied to two electrides. A sample of Li ^+(PMPCY)e^- underwent a first-order decomposition reaction with a half life of 110 hrs at 23^circC while a sample of K^+(C222)e ^- decomposed autocatalytically in under 2 days at -57^circ C. The results point to two different mechanisms of decomposition in electrides. The electrical properties of several electrides were investigated through Impedance Spectroscopy and a.c. and d.c. conductivity methods. D.C. conductivity studies of K^+(C222)e^- indicated a low band gap but high apparent resistivity and marked non-Ohmic behavior for the compound. The high resistivity and non-Ohmic behavior were found to be due to a Schottky barrier at the sample-electrode interface. Four probe a.c. conductivity experiments on a cylindrical sample pellet revealed a band gap of 0.086 eV for the compound and placed an upper limit of 0.189 Omega cm at 130 K on its resistivity. The band gap of the compound may be due to the activated transfer of electrons across grain boundaries in the polycrystalline samples. The electrides Cs^+(15C5) _2e^- and Cs^+(18C6)_2e ^- were shown to exhibit the first ionic conductivity ever seen in electrides. Cs ^+(15C5)_2e ^- undergoes a transition from defect electronic conductivity to ionic conductivity, the latter having an activation energy of 0.7 eV. Cs^+(18C6) _2e^- also exhibited ionic conduction with an activation energy of 1.0 eV. Both compounds exhibited electrochemical cell behavior when placed between one cesium and one stainless steel electrode. The mechanism of the ionic conductivity may involve the release of the cesium cation from its crown ether cage and its reduction by an electron anion of the compound followed by Cs^+ transfer between anionic sites in the crystal lattice. The semiconductor behavior previously seen in Cs^+(18C6) _2e^- was shown to be due to the doping of the

  6. Design VHF Antennas for Space Borne Receivers for SmallSats

    Science.gov (United States)

    Deshpande, Manohar

    2017-01-01

    Space borne microwave remote sensors at VHF/UHF frequencies are important instruments to observe reflective properties of land surfaces through thick and heavy forestation on a global scale. One of the most cost effective ways of measuring land reflectivity at VHF/UHF frequencies is to use signals transmitted by existing communication satellites (operating at VHF/UHF band) as a signal of opportunity (SoOp) signal and passive receivers integrated with airborne/space borne platforms operating in the Low Earth Orbit (LEO). One of the critical components of the passive receiver is two antennas (one to receive only direct signal and other to receive only reflected signal) which need to have ideally high (>30dB) isolation. However, because of small size of host platforms and broad beam width of dipole antennas, achieving adequate isolation between two channels is a challenging problem and need to be solved for successful implementation of space borne SoOp technology for remote sensing. In this presentation a novel enabling VHF antenna technology for Cubesat platforms is presented to receive direct as well as reflected signal with needed isolation. The novel scheme also allows enhancing the gain of individual channels by factor of 2 without use of reflecting ground plane.

  7. Dicty_cDB: VHF729 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ences producing significant alignments: (bits) Value VHF729 (VHF729Q) /CSM/VH/VHF...4-A/CHC421Q.Seq.d/ 139 9e-33 own update 2002.12.27 Homology vs DNA Score E Sequences producing significant alignments: (bits) Value... 139 2e-29 1 dna update 2008.10.31 Homology vs Protein Score E Sequences producing significant alignments: (bits) Value

  8. The Electrical and Dynamical Properties of Biomembranes

    DEFF Research Database (Denmark)

    Mosgaard, Lars Dalskov

    Biological membranes in living organisms play the fundamental role of acting as boundaries and facilitate compartmentalization. From a structural perspective they are essentially constituted by an amphiphilic lipid membrane in which sugars, peptides and proteins are incorporated. These quasi-2...... of the coupling between the membrane and the electrical eld within a universal thermodynamic framework. Within this framework, known electrical phenomena associated with lipid membranes such as o set voltage, electrostriction, piezoelectricity and exoelectricity can be captured and viewed as special cases...... into account the coupling between thermodynamical uctuations and the available heat reservoir. The next step is to combine the knowledge on lipid membranes subjected to an electrical eld with the knowledge on their relaxation behavior and use our understanding to attempt to re-evaluate the results of common...

  9. Electrical Properties of Zinc-Kaolin Composites below its Percolation ...

    African Journals Online (AJOL)

    Bheema

    electrical conduction mechanism of the zinc-kaolin cermet below the percolation threshold is a mixture of both the ... Most of the research works involving cermets have been on their electrical properties above the percolation .... organic vehicles and of course sintering of individual particles in the cermet have occurred to an.

  10. Lunar sample electrical properties. [with emphasis on electroconductivity and permittivity

    Science.gov (United States)

    Olhoeft, G. R.; Strangway, D. W.; Frisillo, A. L.

    1973-01-01

    Electrical conductivity and dielectric constant measurements have been performed in vacuum on solid and soil samples over a wide range of temperatures and frequencies. The temperature dependence and the frequency response of the dielectric properties together with the temperature dependence of the DC conductivity have permitted us to propose a mathematical model describing the mechanisms controlling the electrical properties. In general, each lunar sample has several distributed mechanisms, each mechanism dominant in a particular temperature range.

  11. From ultrafast spectroscopy to bidirectional molecular switches: DHA/VHF

    Science.gov (United States)

    Schmidhammer, U.; De Waele, V.; Buntinx, G.; Riedle, E.

    The photoconversion from dihydroazulene (DHA) to vinylheptafulvene (VHF) is governed by two mechanisms: The ring opening proceeds on the excited energy surface on the picosecond time scale. It is followed by an intemal conversion to the VHF ground state that is accelerated by the presence of a conical intersection in the case of cyclopenta-DHA. This conical intersection hinders the photoinduced back reaction from the final VHF products. However, we successfully photoconverted the cyanophenyl-VHF-cis back to the DHA with a second delayed pulse. This opens the route to the development of bistable DHAs.

  12. Biological and electrical properties of biosynthesized silver ...

    Indian Academy of Sciences (India)

    In this work, silver nanoparticles (AgNPs) were synthesized biochemically at room temperature using aqueous extract of rhizome of Rheum australe plant. The as-synthesized AgNPs were further studied for their morphological, biological and electrical characterization. The morphological studies, such as scanning electron ...

  13. Biological and electrical properties of biosynthesized silver ...

    Indian Academy of Sciences (India)

    Administrator

    using aqueous extract of rhizome of Rheum australe plant. The as-synthesized AgNPs were further studied for their morphological, biological and electrical characterization. The morphological studies, such as scanning electron microscopy, X-ray diffraction and UV–vis spectrum confirmed their successful synthesis.

  14. Synthesis, characterization, thermal and electrical properties of ...

    Indian Academy of Sciences (India)

    The anticorrosive property of a coating of PANI/[Co(mea)2(H2O)2Cl2] composite on mild steel coupon in 3 M HNO3 was evaluated using weight loss measurement and compared with pure polyaniline coating. The said composite has shown anticorrosive property and can thus, act as a potent dopant for enhancing corrosion ...

  15. Thermal to electricity conversion using thermal magnetic properties

    Science.gov (United States)

    West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

    2010-04-27

    A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

  16. Evaluating the Mechanical Properties of Tomato Based on Electrical Conductivity

    Directory of Open Access Journals (Sweden)

    M Ghasemi

    2014-09-01

    Full Text Available Evaluation of mechanical and electrical properties of agricultural products plays an important role in equipment design and optimizing post-harvest operations. Among the crops, tomato and its products are the major processing industries in the world and its economic importance is increasing. Considering the importance of the quality and various post harvesting uses of tomato, the evaluation of mechanical properties including rupture force and deformation and the work done to establish the rupture of two tomato cultivars (Petoearly CH and Newton were studied under penetration test based on the electrical conductivity. These properties were measured at three levels of 1, 3 and 5 days after harvesting. The evaluated mechanical properties of both cultivars were decreased by increasing the storage time. Interaction of cultivar and time were significant at the 1% level, for all mechanical parameters except the deformation failure in both cultivars. The electrical conductivity of both cultivars was decreased by increasing the storage time. Interaction of cultivar and time on the electrical conductivity of both cultivars were significant at the 1% level. Significant relationships were found at the 1% level between electrical conductivity and mechanical properties except for deformation of Petoearly CH cultivar. Among the mechanical parameters, rupture forces and rupture works of both cultivars were highly correlated with the electrical conductivity.

  17. Electrical Impedance Tomography: Tissue Properties to Image Measures.

    Science.gov (United States)

    Adler, Andy; Boyle, Alistair

    Electrical impedance tomography (EIT) uses electrical stimulation and measurement at the body surface to image the electrical properties of internal tissues. It has the advantage of noninvasiveness and high temporal resolution but suffers from poor spatial resolution and sensitivity to electrode movement and contact quality. EIT can be useful to applications, where there are conductive contrasts between tissues, fluids, or gasses, such as imaging of cancerous or ischemic tissue or functional monitoring of breathing, blood flow, gastric motility, and neural activity. The past decade has seen clinical application and commercial activity using EIT for ventilation monitoring. Interpretation of EIT-based measures is complex, and this review paper focuses on describing the image interpretation "pathway." We review this pathway, from Tissue Electrical Properties, EIT Electrodes & Hardware, Sensitivity, Image Reconstruction, Image Processing to EIT Measures. The relationship is discussed between the clinically relevant parameters and the reconstructed properties. An overview is given of areas of EIT application and of our perspectives for research and development.Electrical impedance tomography (EIT) uses electrical stimulation and measurement at the body surface to image the electrical properties of internal tissues. It has the advantage of noninvasiveness and high temporal resolution but suffers from poor spatial resolution and sensitivity to electrode movement and contact quality. EIT can be useful to applications, where there are conductive contrasts between tissues, fluids, or gasses, such as imaging of cancerous or ischemic tissue or functional monitoring of breathing, blood flow, gastric motility, and neural activity. The past decade has seen clinical application and commercial activity using EIT for ventilation monitoring. Interpretation of EIT-based measures is complex, and this review paper focuses on describing the image interpretation "pathway." We review this

  18. Optical and electrical properties of nickel xanthate thin films

    Indian Academy of Sciences (India)

    Administrator

    range of properties such as optical, electrical and mag- netic characteristics. It has been shown that these thin films show different properties such as an antibacterial agent, magnetic and semi-conductor material, which allowed them to be used for data storage, solar cell produc- tion, water purification, etc. (Gao et al 1997; ...

  19. Electrical and thermal properties of graphite/polyaniline composites

    Energy Technology Data Exchange (ETDEWEB)

    Bourdo, Shawn E., E-mail: sxbourdo@ualr.edu [Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204 (United States); Warford, Brock A.; Viswanathan, Tito [Department of Chemistry, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204 (United States)

    2012-12-15

    A composite of a carbon allotrope (graphite) and an inherently conducting polymer, polyaniline (PANI), has been prepared that exhibits an electrical conductivity greater than either of the two components. An almost 2-fold increase in the bulk conductivity occurs when only a small mass fraction of polyaniline exists in the composite (91% graphite/ 9% polyaniline, by mass). This increase in dc electrical conductivity is curious since in most cases a composite material will exhibit a conductivity somewhere between the two individual components, unless a modification to the electronic nature of the material occurs. In order to elucidate the fundamental electrical properties of the composite we have performed variable temperature conductivity measurements to better understand the nature of conduction in these materials. The results from these studies suggest a change in the mechanism of conduction as the amount of polyaniline is increased in the composite. Along with superior electrical properties, the composites exhibit an increase in thermal stability as compared to the graphite. - Graphical abstract: (Left) Room temperature electrical conductivity of G-PANI composites at different mass ratios. (Right) Electrical conductivity of G-PANI composites at temperatures from 5 K to 300 K. Highlights: Black-Right-Pointing-Pointer Composites of graphite and polyaniline have been synthesized with unique electrical and thermal properties. Black-Right-Pointing-Pointer Certain G-PANI composites are more conductive and more thermally stable than graphite alone. Black-Right-Pointing-Pointer G-PANI composites exhibit a larger conductivity ratio with respect to temperature than graphite alone.

  20. Structural and electrical properties of selenium nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Prajna, E-mail: prajna111@gmail.com [Department of Physics, Visva-Bharati, Santiniketan, 731235 (India); Department of Physics, Bolpur College, Bolpur, 731204 (India); Konar, Shyamal [Department of Physics, Visva-Bharati, Santiniketan, 731235 (India); Gupta, Bikash C., E-mail: bikashc.gupta@visva-bharati.ac.in [Department of Physics, Visva-Bharati, Santiniketan, 731235 (India)

    2016-01-08

    The electronic structure calculations are systematically carried out within the density functional formalism for understanding the structural and electronic properties of a number of selenium nanotubes. In particular, single walled selenium nanotubes (achiral) are studied in this work. Our investigations reveal that the lower diameter nanotubes are unstable. Beyond certain diameter, the tubes retain their tubular structure and they show metallic property. Furthermore, work-functions of these tubes are found to depend on their diameters and differ from that of the bulk selenium surface. - Highlights: • The selenium tubes become stable and retain tubular shape beyond certain diameter. • In contrary to bulk selenium, the tubular structures show metallic property. • The work-functions of tubes vary with diameter. The amount of variation is 1.2 eV.

  1. Dicty_cDB: VHF823 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available uences producing significant alignments: (bits) Value VHF823 (VHF823Q) /CSM/VH/VH...186Q.Seq.d/ 86 1e-16 own update 2009. 4. 4 Homology vs DNA Score E Sequences producing significant alignments: (bits) Value...-13 1 dna update 2008.10.31 Homology vs Protein Score E Sequences producing significant alignments: (bits) Value

  2. Electrical Properties of Carbon Fiber Support Systems

    CERN Document Server

    Cooper, W; Demarteau, M; Fast, J; Hanagaki, K; Johnson, M; Kuykendall, W; Lubatti, H; Matulik, M; Nomerotski, A; Quinn, B; Wang, J

    2005-01-01

    Carbon fiber support structures have become common elements of detector designs for high energy physics experiments. Carbon fiber has many mechanical advantages but it is also characterized by high conductivity, particularly at high frequency, with associated design issues. This paper discusses the elements required for sound electrical performance of silicon detectors employing carbon fiber support elements. Tests on carbon fiber structures are presented indicating that carbon fiber must be regarded as a conductor for the frequency region of 10 to 100 MHz. The general principles of grounding configurations involving carbon fiber structures will be discussed. To illustrate the design requirements, measurements performed with a silicon detector on a carbon fiber support structure at small radius are presented. A grounding scheme employing copper-kapton mesh circuits is described and shown to provide adequate and robust detector performance.

  3. Thermal and electrical properties of silicon nitride substrates

    Directory of Open Access Journals (Sweden)

    H. S. Dow

    2017-09-01

    Full Text Available This work presents the results of studies on the thermal and electrical properties of sintered silicon nitride to investigate the effects of non-oxide additives. With regard to electrical transport properties, a high electrical resistivity of 1014 ∼ 1015 Ωcm at 323 K was observed with Si3N4 substrates. Typical electrical resistivity and thermal conductivity values of the Si3N4 substrates were 1015 Ωcm and 90 W/mK at room temperature, respectively. Based on the results of XPS measurement, it is suggested that the addition of Nb significantly improved oxygen gettering by the phases of Nb2O5. Based on the analysis of the thermal conductivity of Si3N4 substrates, it appears that the interaction between oxygen and Nb in Si3N4, enhanced the thermal conduction rate of Si3N4.

  4. Electrical properties of molecular crystals; Proprietes electriques des cristaux moleculaires

    Energy Technology Data Exchange (ETDEWEB)

    Barraud, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    This literature survey summarizes the electrical properties of molecular crystals: molecular crystal structure, transport and excitation mechanisms of charge-carriers, and differences compared to inorganic semi-conductors. The main results concerning the electrical conductivity of the most-studied molecular crystals are presented, together with the optical and photo-electrical properties of these crystals. Finally the different types of electrical measurements used are reviewed, as well as the limits of each method. (author) [French] Cette etude bibliographique resume les proprietes electriques des cristaux moleculaires: structure des cristaux moleculaires, mecanismes de transport et d'excitation des porteurs de charge et differences avec les semiconducteurs mineraux. Les principaux resultats sur la conductibilite electrique des cristaux moleculaires les plus etudies y sont exposes, ainsi que les proprietes optiques et photoelectriques de ces cristaux. Enfin les differents types de mesures electriques utilisees sont passees en revue ainsi que les limites de chaque methode. (auteur)

  5. Modelling the electrical properties of concrete for shielding effectiveness prediction

    Science.gov (United States)

    Sandrolini, L.; Reggiani, U.; Ogunsola, A.

    2007-09-01

    Concrete is a porous, heterogeneous material whose abundant use in numerous applications demands a detailed understanding of its electrical properties. Besides experimental measurements, material theoretical models can be useful to investigate its behaviour with respect to frequency, moisture content or other factors. These models can be used in electromagnetic compatibility (EMC) to predict the shielding effectiveness of a concrete structure against external electromagnetic waves. This paper presents the development of a dispersive material model for concrete out of experimental measurement data to take account of the frequency dependence of concrete's electrical properties. The model is implemented into a numerical simulator and compared with the classical transmission-line approach in shielding effectiveness calculations of simple concrete walls of different moisture content. The comparative results show good agreement in all cases; a possible relation between shielding effectiveness and the electrical properties of concrete and the limits of the proposed model are discussed.

  6. Electric Field Structures in Thin Films: Formation and Properties

    DEFF Research Database (Denmark)

    Cassidy, Andrew; Plekan, Oksana; Balog, Richard

    2014-01-01

    by combining layers of different spontelectric materials. This is demonstrated using the spontelectric materials nitrous oxide, toluene, isoprene, isopentane, and CF2Cl2. These yield a variety of tailored electric field structures, with individual layers harboring fields between 107 and 108 V/m. Fields may......A newly discovered class of molecular materials, so-called “spontelectrics”, display spontaneous electric fields. Here we show that the novel properties of spontelectrics can be used to create composite spontelectrics, illustrating how electric fields in solid films may be structured on the nanoscale...

  7. ELECTRICAL AND THERMODYNAMIC PROPERTIES OF A COLLAGEN SOLUTION

    Directory of Open Access Journals (Sweden)

    Jaromír Štancl

    2017-06-01

    Full Text Available This paper focuses on measurements of the electrical properties, the specific heat capacity and the thermal conductivity of a collagen solution (7.19% mass fraction of native bovine collagen in water. The results of our experiments show that specific electrical conductivity of collagen solution is strongly dependent on temperature. The transition region of collagen to gelatin has been observed from the measured temperature dependence of specific electrical conductivity, and has been confirmed by specific heat capacity measurements by a differential scanning calorimetry.

  8. Polymer composites with graphene nanofillers: electrical properties and applications.

    Science.gov (United States)

    Tjong, Sie Chin

    2014-02-01

    Graphene with extraordinary high elastic modulus and excellent electrical conductivity has good prospects for use as the filler material for fabricating novel polymer composites designed for electrostatic discharge and EMI shielding protection, field emission, gas sensor, and fuel cell applications. Large amounts of graphene oxide (GO) can be obtained by wet chemical oxidation of graphite into a mixture of concentrated sulfuric acid, sodium nitrate and potassium permanganate. Accordingly, carbon atoms in the basal plane and edges of GO are decorated with oxygenated functional groups, forming an electrical insulator. To restore electrical conductivity, chemical reduction or thermal annealing is needed to eliminate oxygenated groups of GO. However, such treatments induce internal defects and remove oxygenated atoms of GO partially. The remnant-oxygenated groups affect electrical conductivity of graphene greatly. Nevertheless, reduced graphene oxide and thermally reduced graphene oxide are sufficiently conductive to form polymer nanocomposites at very low percolation threshold. This review provides the fundamentals and state-of-the-art developments in the fabrication methods and electrical property characterizations as well as the applications of novel graphene/polymer nanocomposites. Particular attention is paid to their processing-structural-electrical property relationships.

  9. Conjugated electrical properties of Au nanoparticle–polyaniline network

    Science.gov (United States)

    Usami, Yuki; Otsuka, Yoichi; Naitoh, Yasuhisa; Matsumoto, Takuya

    2017-12-01

    We investigated the electrical properties of a two-dimensional (2D) network consisting of multiple Au nanoparticles (AuNPs) and self-doped polyaniline sulfonate (SPAN). Nonlinear current–voltage (I–V) characteristics with wide variations were observed in the networks. The temperature dependence of the I–V characteristics exhibited a short localization length, suggesting conjugated electronic properties of the AuNP–SPAN network. This result provides a new direction for network-based molecular electronic devices.

  10. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    Science.gov (United States)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

  11. Mapping the electrical properties of large-area graphene

    DEFF Research Database (Denmark)

    Bøggild, Peter; Mackenzie, David; Whelan, Patrick Rebsdorf

    2017-01-01

    , and a high measurement effort per device. In this topical review, we provide a comprehensive overview of the issues that need to be addressed by any large-area characterisation method for electrical key performance indicators, with emphasis on electrical uniformity and on how this can be used to provide......The significant progress in terms of fabricating large-area graphene films for transparent electrodes, barriers, electronics, telecommunication and other applications has not yet been accompanied by efficient methods for characterizing the electrical properties of large-area graphene. While...... in the early prototyping as well as research and development phases, electrical test devices created by conventional lithography have provided adequate insights, this approach is becoming increasingly problematic due to complications such as irreversible damage to the original graphene film, contamination...

  12. Temperature effects on the electrical properties of multiphase polymer composites

    Science.gov (United States)

    De Vivo, Biagio; Guadagno, Liberata; Lamberti, Patrizia; Raimondo, Marialuigia; Spinelli, Giovanni; Tucci, Vincenzo; Vertuccio, Luigi; Vittoria, Vittoria

    2014-05-01

    A study concerning the temperature dependence of some electrical properties of multiphase nanocomposite systems based on epoxy matrix, loaded with a 1% of multi-walled carbon nanotube (MWCNT) and different amounts of Hydrotalcite clay (HT), is presented. An extensive electrical characterization in DC was carried out highlighting that, consistently with the fluctuation-induced tunneling model, the electrical resistivity of the composites are characterized by a negative temperature coefficient (NTC) since it decreases monotonically with increasing temperature in the range 30-110°C. Furthermore, current-voltage (I-V) and temperature-voltage (T-V) characteristics with a perfect linear behavior are detected. The influence of different clay content on the electrical performance of the composites is also investigated. The interesting results open a new routes for such composites due their possible applications in the field of temperature sensor.

  13. Structural, optical and electrical properties of chemically deposited ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 29; Issue 5. Structural, optical and electrical properties of chemically ... R H Bari1 L A Patil1 P P Patil2. P.G. Department of Physics, Pratap College, Amalner 425 401, India; Department of Physical Sciences, North Maharashtra University, Jalgaon 425 001, India ...

  14. Mechanical, microstructure and electrical properties of ternary ZnO ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 38; Issue 3. Mechanical, microstructure and electrical properties of ternary ZnO–V2O5–Mn3O4 varistor with sintering temperature. S El-Rabai A H Khafagy M T Dawoud M T Attia. Volume 38 Issue 3 June 2015 pp 773-781 ...

  15. Structural and electrical transport properties of nanosized La0 ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 70; Issue 4. Structural and electrical transport properties of nanosized La0.67Ca0.33MnO3 sample synthesized by a simple low-cost ... Author Affiliations. S Keshri1 V Dayal1. Department of Applied Physics, Birla Institute of Technology, Mesra, Ranchi 835 215, India ...

  16. Effect of gamma radiation on optical and electrical properties of ...

    Indian Academy of Sciences (India)

    Wintec

    of the as-deposited thin films and that of the thin films exposed to various levels of gamma radiation dose clearly show that the ... changes in both the optical and electrical properties indicate that TeO2 thin films can be used as the real time gamma radiation ... interest for the fundamental science and technology. The origin of ...

  17. Effect of substrate temperature on electrical and magnetic properties ...

    Indian Academy of Sciences (India)

    electrical and magnetic properties of epitaxial. La1−xPbxMnO3 films. AJAY SINGH1,∗. , D K ASWAL1, SHASHWATI SEN1, K SHAH1, L C ... The discovery of colossal magnetoresistace in pervoskite manganite La1−x Ax MnO3 (A = alkaline earth metals, bivalent ion) has attracted extensive research not only for understand-.

  18. Electrical properties of silver selenide thin films prepared by reactive ...

    Indian Academy of Sciences (India)

    The electrical properties of silver selenide thin films prepared by reactive evaporation have been studied. Samples show a polymorphic phase transition at a temperature of 403 ± 2 K. Hall effect study shows that it has a mobility of 2000 cm2V–1s–1 and carrier concentration of 1018 cm–3 at room temperature. The carriers ...

  19. Synthesis, characterization and electrical properties of visible-light ...

    Indian Academy of Sciences (India)

    nature, second, the phase structure of composite remains unchanged during doping of Pt into ZnO crystal. Results ... doping of ZnO particle with Pt a known concentration of hex- achloroplatinic acid (3–9%, w/v) was added in the surfactant solution. For the analysis of electrical properties a pellet of 13 mm in diameter and of ...

  20. Study of microhardness and electrical properties of proton irradiated ...

    Indian Academy of Sciences (India)

    Polyethersulfone (PES) films were irradiated with 3 MeV proton beams in the fluence range 1013–1015 ions/cm2. The radiation induced changes in microhardness was investigated by a Vickers' microhardness tester in the load range 100–1000 mN and electrical properties in the frequency range 100 Hz–1 MHz by an LCR ...

  1. Electrical properties of chemically prepared nonstoichiometric CuIn ...

    Indian Academy of Sciences (India)

    TECS

    Ohashi T, Inakoshi K, Hashimoto Y and Ito K 1988 Solar En- ergy Mater. & Solar Cells 50 37. Sharma R P 1991 Studies on structural, electrical and optical properties of chalcopyrite semiconductor thin films, Ph.D. Thesis, University of Rajasthan, Jaipur. Sutrave D S, Shahane G S, Patil V B and Deshmukh L P 2000. Mater.

  2. Electrical Machines Laminations Magnetic Properties: A Virtual Instrument Laboratory

    Science.gov (United States)

    Martinez-Roman, Javier; Perez-Cruz, Juan; Pineda-Sanchez, Manuel; Puche-Panadero, Ruben; Roger-Folch, Jose; Riera-Guasp, Martin; Sapena-Baño, Angel

    2015-01-01

    Undergraduate courses in electrical machines often include an introduction to their magnetic circuits and to the various magnetic materials used in their construction and their properties. The students must learn to be able to recognize and compare the permeability, saturation, and losses of these magnetic materials, relate each material to its…

  3. Effect of substrate temperature on electrical and magnetic properties ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 58; Issue 5-6. Effect of substrate temperature on electrical and magnetic properties of epitaxial La 1 − Pb MnO3 films. Ajay Singh D K Aswal Shashwati Sen K Shah L C Gupta S K Gupta V C Sahni. Colossal Magnetoresistance & Other Materials Volume 58 Issue ...

  4. Effect of gamma radiation on electrical and optical properties of ...

    Indian Academy of Sciences (India)

    We have studied in detail the gamma radiation induced changes in the electrical properties of the (TeO2)0.9 (In2O3)0.1 thin films of different thicknesses, prepared by thermal evaporation in vacuum. The current–voltage characteristics for the as-deposited and exposed thin films were analysed to obtain current versus dose ...

  5. Topological Nanocolloids with Facile Electric Switching of Plasmonic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Ye; Smalyukh, Ivan I.

    2015-12-01

    Combining topology and plasmonics paradigms in nanocolloidal systems may enable new means of pre-engineering desired composite material properties. Here we design and realize orientationally ordered assemblies of noble metal nanoparticles with genus-one topology and unusual long-range ordering mediated by their interactions with the surrounding nematic fluid host. Facile electric switching of these composites is reminiscent of that of pristine liquid crystals (LCs), but provides a means of reconfiguring the nanoparticle assembly and thus also the ensuing composite medium's optical properties. Our findings may lead to formation of new molecular-colloidal soft matter phases with unusual optical properties, as well as optical metamaterials.

  6. Magnetic resonance electric property imaging of brain tissues.

    Science.gov (United States)

    Zhang, Xiaotong; Zhu, Shanan; He, Bin

    2009-01-01

    The electric properties (EPs) of brain tissues, i.e., the electric conductivity and permittivity, can provide important information for diagnosis of various brain disorders. A high-field MRI system is accompanied by significant wave propagation effects, and the radio frequency (RF) radiation is dependent on EPs of the biological tissue. Based on the measurement of the active transverse magnetic component of the applied RF field (known as B1-mapping technique), we have developed a dual-excitation algorithm, which uses two sets of measured B1 data, to noninvasively reconstruct the biological tissue's electric properties. A series of computer simulations were conducted to evaluate the feasibility and performance of the proposed method on a 3-D head model within a birdcage coil and a transverse electromagnetic coil. Compared with other B1-mapping based reconstruction algorithms, our approach provides superior performance without the need for iterative computations. The present simulation results indicate good reconstruction of electric properties of brain tissues from noninvasive MRI B1 mapping.

  7. Nonlinear electrical properties of Si three-terminal junction devices

    DEFF Research Database (Denmark)

    Fantao, Meng; Jie, Sun; Graczyk, Mariusz

    2010-01-01

    This letter reports on the realization and characterization of silicon three-terminal junction devices made in a silicon-on-insulator wafer. Room temperature electrical measurements show that the fabricated devices exhibit pronounced nonlinear electrical properties inherent to ballistic electron...... transport in a three-terminal ballistic junction (TBJ) device. The results show that room temperature functional TBJ devices can be realized in a semiconductor material other than high-mobility III-V semiconductor heterostructures and provide a simple design principle for compact silicon devices...

  8. Electrical property studies of neutron-transmutation-doped silicon

    Energy Technology Data Exchange (ETDEWEB)

    Cleland, J.W.; Fleming, P.H.; Westbrook, R.D.; Wood, R.F.; Young, R.T.

    1978-01-01

    Results of studies of electrical properties of neutron-transmutation-doped (NTD) silicon are presented. Annealing requirements to remove lattice damage were obtained. The electrical role of clustered oxygen and defect-oxygen complex was investigated. An NTD epitaxial layer on a heavily doped n- or p- type substrate can be produced. There is no evident interaction between lithium introduced by diffusion and phosphorous 31 introduced by irradiation. There may be some type of pairing reaction between lithium 7 introduced by boron 10 fission and any remaining boron. (FS)

  9. Tunable terahertz optical properties of graphene in dc electric fields

    Science.gov (United States)

    Dong, H. M.; Huang, F.; Xu, W.

    2018-03-01

    We develop a simple theoretical approach to investigate terahertz (THz) optical properties of monolayer graphene in the presence of an external dc electric field. The analytical results for optical coefficients such as the absorptance and reflectivity are obtained self-consistently on the basis of a diagrammatic self-consistent field theory and a Boltzmann equilibrium equation. It is found that the optical refractive index, reflectivity and conductivity can be effectively tuned by not only a gate voltage but also a driving dc electric field. This study is relevant to the applications of graphene as advanced THz optoelectronic devices.

  10. Thermodynamic properties and electrical conductivity of strongly correlated plasma media

    Energy Technology Data Exchange (ETDEWEB)

    Filinov, V S; Levashov, P R; BoTan, A V; Fortov, V E [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13 bldg 2, Moscow 125412 (Russian Federation); Bonitz, M [Christian-Albrechts-Universitaet zu Kiel, Institut fuer Theoretische Physik und Astrophysik, Leibnizstrasse 15, 24098 Kiel (Germany)

    2009-05-29

    We study thermodynamic properties and the electrical conductivity of dense hydrogen and deuterium using three methods: classical reactive Monte Carlo, direct path integral Monte Carlo (PIMC) and a quantum dynamics method in the Wigner representation of quantum mechanics. We report the calculation of the deuterium compression quasi-isentrope in good agreement with experiments. We also solve the Wigner-Liouville equation of dense degenerate hydrogen calculating the initial equilibrium state by the PIMC method. The obtained particle trajectories determine the momentum-momentum correlation functions and the electrical conductivity and are compared with available theories and simulations.

  11. Optical properties of graphene nanocones under electric and magnetic fields

    Science.gov (United States)

    Ulloa, P.; Pacheco, M.; Latgé, A.

    2017-11-01

    Here we present a theoretical study of the optical properties of graphene nanocones tuned by external electric and magnetic fields. We investigate the effects of the size and topology of the carbon nanostructures on the density of states and on the electro- and magneto-absorption of linearly polarized electromagnetic radiation in different nanocone geometries. We find that the electric field induces changes in the electric charge distribution mainly at the cone edges. In the infrared range the absorption coefficient shows a peculiar dependence on the electric field (magnitude and direction) and on the photon polarization for all investigated structures. Our results suggest that the electric field may be used to control the electric charge at the apex and for a selective light absorption. The presence of an axial magnetic field induces new features in the nanocone density of states due to the induced localization effects. For high fields the density of states exhibits a sequence of peaks resembling the graphene Landau spectra. The magneto-absorption spectra present a series of resonances strongly sensitive to the photon polarization opening routes for manipulation of the optical responses.

  12. Dicty_cDB: VHF145 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available VH (Link to library) VHF145 (Link to dictyBase) - - - Contig-U15430-1 VHF145E (Link...) Clone ID VHF145 (Link to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U15430-1 Ori...ology vs DNA Score E Sequences producing significant alignments: (bits) Value N AC116984 |AC116984.2 Dictyos... theta DNA for complete sequence of nucleomorph chromosome 2. 48 2e-07 2 ES451909 | PREDICTED: similar to PI...al 16.0 %: nuclear 8.0 %: vacuolar 8.0 %: endoplasmic reticulum 4.0 %: cytoskeletal >> prediction for VHF145

  13. Effect of power on growth of nanocrystalline silicon films deposited by VHF PECVD technique for solar cell applications

    Science.gov (United States)

    Juneja, Sucheta; Verma, Payal; Savelyev, Dmitry A.; Khonina, Svetlana N.; Sudhakar, S.; Kumar, Sushil

    2016-04-01

    An investigation of the effect of power on the deposition of nanocrystalline silicon thin films were carried out using a gaseous mixture of silane and hydrogen in the 60MHz assisted VHF plasma enhanced chemical vapor deposition (PECVD) technique. The power was varied from 10 to 50 watt maintaining all other parameters constant. Corresponding layer properties w.r.t. material microstructure, optical, hydrogen content and electrical transport are studied in detail. The structural properties have been studied by Raman spectroscopy and x-ray diffraction (XRD). The presence of nano-sized crystals and their morphology have been investigated using atomic force microscopy (AFM). The role of bonded hydrogen content in the films have been studied from the results of Fourier transform infrared spectroscopy. It was observed from the results that with increase in power, crystalline volume fraction increases and crystallite size changes from 4 to 9 nm. The optical band gap varies from 1.7 to 2.1eV due to quantum confinement effect and which further can be explained with reduced hydrogen content. These striking features of nc-Si films can be used to fabricate stable thin film solar cells.

  14. Broadband Grounded Vertical Antennas for 30-180 MHZ (VHF)

    Science.gov (United States)

    2013-10-18

    antennas are well known for their broadband gain (monocone, bicone ) but are never combined with a monopole. An eccentric combination of broadband...DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Broadband Grounded Vertical Antennas For 30-180 MZH (VHF) 5a. CONTRACT NUMBER 5b...18 Attorney Docket No. 102536 1 of 17 BROADBAND GROUNDED VERTICAL ANTENNAS FOR 30-180 MHZ (VHF) STATEMENT OF GOVERNMENT INTEREST

  15. Analysis of the VHF-UHF electromagnetic radiation of lightning: Application to a model of the negative stepped leader propagation

    Science.gov (United States)

    Taudiere, Isabelle

    1991-03-01

    The space and time characteristics of the VHF-UHF radiation from lightning are analyzed on the bases of 300 MHz emission sources, localized in three dimensions by interferometric measurements. The main phases that contribute to the development of intracloud lightning are examined in detail, also using electric field measurements at the lower frequency. This research is complemented by an experimental and theoretical analysis of long discharge (8m) radio emissions generated with both polarities in the laboratory. These investigations revealed that the VHF radiation is associated with the channel reillumination phase accompanying each step in the negative spark. The outcome of this work is the creation of a simple model for the propagation of the negative leader. The current and the radiated field during this phase of the discharge are computed from an equivalent electric circuit using the physical laws governing the variation of resistance. The extrapolation of these results to the case of the stepped leader of natural lightning is discussed.

  16. Mechanical and Electrical Properties of Organogels with Multiwall Carbon Nanotubes

    Science.gov (United States)

    Moniruzzaman, Mohammad; Winey, Karen

    2008-03-01

    Organogels are fascinating thermally reversible viscoelastic materials that are comprised of an organic liquid and low concentrations (typically gelators. We have fabricated the first organogel/carbon nanotube composites using 12-hydroxystearic acid (HSA) as the gelator molecule and pristine and carboxylated multi-wall carbon nanotubes as the nanofillers and 1,2-dichlorobenzene as the organic solvent. We have achieved significant improvements in the mechanical and electrical properties of organogels by incorporating these carbon nanotubes. For example, the linear viscoelastic regime of the HSA organogel, an indicator of the strength of the gel, extends by a factor of 4 with the incorporation of 0.2 wt% of the carboxylated nanotubes. Also, the carbon nanotubes (specially the pristine tubes) improve the electrical conductivity of the organogels, e.g. six orders of magnitude enhancement in electrical conductivity with 0.2 wt% of pristine tubes. Differential scanning calorimetry experiments indicate that the nanotubes do not affect the thermoreversibility of the organogels.

  17. Electrical Properties of Composite Materials with Electric Field-Assisted Alignment of Nanocarbon Fillers

    Science.gov (United States)

    Yakovenko, Olena; Matzui, Ludmila; Danylova, Ganna; Zadorozhnii, Victor; Vovchenko, Ludmila; Perets, Yulia; Lazarenko, Oleksandra

    2017-07-01

    The article reports about electric field-induced alignment of the carbon nanoparticles embedded in epoxy matrix. Optical microscopy was performed to consider the effect of the electric field magnitude and configuration, filler morphology, and aspect ratio on alignment process. Characteristic time of aligned network formation was compared with modeling predictions. Carbon nanotube and graphite nanoplatelet rotation time was estimated using an analytical model based on effective medium approach. Different depolarization factor was applied according to the geometries of the particle and electric field. Solid nanocomposites were fabricated by using AC electric field. We have investigated concentration dependence of electrical conductivity of graphite nanoplatelets/epoxy composites using two-probe technique. It was established that the electrical properties of composites with random and aligned filler distribution are differ by conductivity value at certain filler content and distinguish by a form of concentration dependence of conductivity for fillers with different morphology. These differences were explained in terms of the dynamic percolation and formation of various conductive networks: chained in case of graphite nanoplatelets and crossed framework in case of carbon nanotubes filler.

  18. Electric field alignment of nanofibrillated cellulose (NFC) in silicone oil: impact on electrical properties.

    Science.gov (United States)

    Kadimi, Amal; Benhamou, Karima; Ounaies, Zoubeida; Magnin, Albert; Dufresne, Alain; Kaddami, Hamid; Raihane, Mustapha

    2014-06-25

    This work aims to study how the magnitude, frequency, and duration of an AC electric field affect the orientation of two kinds of nanofibrillated cellulose (NFC) dispersed in silicone oil that differ by their surface charge density and aspect ratio. In both cases, the electric field alignment occurs in two steps: first, the NFC makes a gyratory motion oriented by the electric field; second, NFC interacts with itself to form chains parallel to the electric field lines. It was also observed that NFC chains become thicker and longer when the duration of application of the electric field is increased. In-situ dielectric properties have shown that the dielectric constant of the medium increases in comparison to the randomly dispersed NFC (when no electric field is applied). The optimal parameters of alignment were found to be 5000 Vpp/mm and 10 kHz for a duration of 20 min for both kinds of NFC. The highest increase in dielectric constant was achieved with NFC oxidized for 5 min (NFC-O-5 min) at the optimum conditions mentioned above.

  19. Sintering and electrical properties of strontium-doped lanthanum manganite

    Energy Technology Data Exchange (ETDEWEB)

    Tarrago, Diego Pereira; Sousa, Vania Caldas de [Universidade Federal do Rio Grande do Sul (LABIOMAT/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Biomateriais], Email: dptarrago@gmail.com; Moreno Buriel, Berta; Chinarro Martini, Eva; Jurado Egea, Jose Ramon [Consejo Superior de Investigaciones Cientificas (ICV/CSIC), Madrid (Spain). Inst. de Ceramica y Vidrio; Malfatti, Celia de Fraga [Universidade Federal do Rio Grande do Sul (LAPEC/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Pesquisa em Corrosao

    2010-07-01

    Lanthanum strontium manganites (LSM) are potential materials for cathode applications in solid oxide fuel cells (SOFC) due to their good catalytic activity, chemical stability and compatibility with electrolyte materials in high temperatures. The sinterability of single phase La{sub 1-x}Sr{sub x}Mn{sub O3} (x=0.18) perovskite powders and the electrical properties of the resulting samples are analyzed in this study. Using a heating microscope, the powders were pressed and sintered at different pressures and temperatures, resulting in an open porosity of 33.36% when compacted at 125 MPa and sintered at 1200 degree C. Top and cross-section s canning electron microscopy (SEM) micrographs revealed interconnected pores in the sintered body and, hence, a suitable microstructure for the application. The activation energy for conductance was 0.04 eV and the tested LSM bulk started to exhibit adequate electrical properties at about 500 degree C. (author)

  20. A SOFTWARE FOR SIMULATING ELECTRICAL PROPERTIES OF PASSIVE DENDRITES

    Directory of Open Access Journals (Sweden)

    Yalçın İŞLER

    2006-01-01

    Full Text Available In this study, a software is introduced for simulating the electrical properties of passive dendrite based on the cable theory. Dendrites along which the synaptic information is conveyed are the largest component of a neuron in surface area. The Cable theory for dendritic neurons addresses to current-voltage relations in a continuous passive dendritic tree. It is briefly summarized that the cable theory related to passive cables and dendrites, which is a useful approximation and an important reference for excitable cases. The proposed software can be used to construct user-defined dendritic tree model. The user can define the model in detail, display the constructed dendritic tree, and examine the basic electrical properties of the dendritic tree.

  1. Effect of copper doping on structural, optical and electrical properties ...

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/boms/037/01/0053-0060. Keywords. Ternary semiconductor compounds; CBD method; structural properties; optical and electrical studies. Abstract. Cd0.8Zn0.2S:Cu films of 1.3–6.1 mole percentage of copper have been grown on mica substrate by using chemical bath deposition technique ...

  2. Thermodynamic properties and electrical conductivity of strongly correlated plasma media

    OpenAIRE

    Filinov, V. S.; Levashov, P. R.; Boţan, A. V.; Bonitz, M.; Fortov, V E

    2008-01-01

    We study thermodynamic properties and the electrical conductivity of dense hydrogen and deuterium using three methods: classical reactive Monte Carlo (REMC), direct path integral Monte Carlo (PIMC) and a quantum dynamics method in the Wigner representation of quantum mechanics. We report the calculation of the deuterium compression quasi-isentrope in good agreement with experiments. We also solve the Wigner-Liouville equation of dense degenerate hydrogen calculating the initial equilibrium st...

  3. Electrical Properties of Zinc-Kaolin Composites below its Percolation ...

    African Journals Online (AJOL)

    In this paper, we present some electrical properties of the zinc-kaolin cermet resistors with zinc metal fillers below the percolation threshold. Rectangular cermet rods of dimensions 65 mm by 6.5 mm by 3.2 mm were produced in a mould with semi-dry the zinc/kaolin powder mixture which is compressed with a force of about ...

  4. irradiation on the optical and electrical properties of buffer solution

    African Journals Online (AJOL)

    Pure and aluminum doped (0.001 wt %Al) CdS thin films were deposited on microscope glass slides using buffer solution growth technique based on CdSO4 as the cadmium source, thiourea as the sulphur source, and (NH4)2 SO4 as a buffer. The effects of gamma radiation on the optical and electrical properties of the ...

  5. The elusive memristor: properties of basic electrical circuits

    Energy Technology Data Exchange (ETDEWEB)

    Joglekar, Yogesh N; Wolf, Stephen J [Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202 (United States)], E-mail: yojoglek@iupui.edu

    2009-07-15

    We present an introduction to and a tutorial on the properties of the recently discovered ideal circuit element, a memristor. By definition, a memristor M relates the charge q and the magnetic flux {phi} in a circuit and complements a resistor R, a capacitor C and an inductor L as an ingredient of ideal electrical circuits. The properties of these three elements and their circuits are a part of the standard curricula. The existence of the memristor as the fourth ideal circuit element was predicted in 1971 based on symmetry arguments, but was clearly experimentally demonstrated just last year. We present the properties of a single memristor, memristors in series and parallel, as well as ideal memristor-capacitor (MC), memristor-inductor (ML) and memristor-capacitor-inductor (MCL) circuits. We find that the memristor has hysteretic current-voltage characteristics. We show that the ideal MC (ML) circuit undergoes non-exponential charge (current) decay with two time scales and that by switching the polarity of the capacitor, an ideal MCL circuit can be tuned from overdamped to underdamped. We present simple models which show that these unusual properties are closely related to the memristor's internal dynamics. This tutorial complements the pedagogy of ideal circuit elements (R, C and L) and the properties of their circuits, and is aimed at undergraduate physics and electrical engineering students.

  6. Metal nanoparticle fluids with magnetically induced electrical switching properties

    Science.gov (United States)

    Kim, Younghoon; Cho, Jinhan

    2013-05-01

    We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media.We report the successful preparation of solvent-free metal nanoparticle (NP) fluids with multiple-functionalities, such as rheological properties, magnetism, ionic conductivity, and electrical properties, allowing for facile synthesis and mass production. The gold nanoparticles (AuNPs) used in this study were synthesized using tetraoctylammonium bromide (TOABr) in toluene and then directly phase-transferred to solvent-free low-molecular-weight (Mw) imidazolium-type ionic liquid media containing thiol groups (i.e., IL-SH). Magnetic metal fluids (i.e., MIL-SH-AuNPs) were prepared by the addition of FeCl3 powder to metal fluids (i.e., IL-SH-AuNPs). These fluids showed relatively high ionic and electrical conductivities compared with those of conventional metal NP fluids based on organic ILs with high Mw. Furthermore, it was demonstrated that these fluids could be used as electric switches operated using an external magnetic field in organic media. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00653k

  7. On the Variations of Electricity, Lightning and Storm Properties

    Science.gov (United States)

    Peterson, M. J.; Deierling, W.; Liu, C.; Mach, D. M.; Kalb, C. P.

    2015-12-01

    Electrified clouds -thunderstorms if lightning is detected, and electrified shower clouds otherwise - produce various currents that contribute to the Global Electric Circuit (GEC). This study aims to use observations of storm properties and lightning characteristics, as well as passive microwave estimates of above-cloud electric fields to compare possible current contributions from a wide variety of storms including isolated thunderstorms, Mesoscale Convective Systems, and otherwise similar storms that occur over land or over the ocean. Variations in Lightning Imaging Sensor (LIS) optical flash properties are also considered in the context of how they relate to the properties of the parent storm and why they differ substantially between land and ocean. This study relies on observations from the Tropical Rainfall Measuring Mission (TRMM) satellite that include radar profiles from the Precipitation Radar (PR), passive microwave observations from the TRMM Microwave Imager (TMI), infrared imagery from the Visible and Infrared Scanner (VIRS), and optical lightning observations from LIS. Observations and derived parameters such as rain rates and electric field estimates are integrated into two databases: a Precipitation Feature (PF) database that summarizes the properties of storms defined by near surface rainfall, and an Illuminated Cloud Feature (ICF) database that summarizes the properties of the storm region illuminated by LIS lightning flashes. The ICF database is built to examine factors that are related to how optical energy can be distributed across the flash footprint in different types of clouds and different viewing conditions that will have consequences for the Geostationary Lightning Mapper (GLM) onboard the upcoming GOES-R satellite.

  8. Observation of strong VHF-radar echoes from the E-region at 69°N and 54°N: Echo properties, relation to sporadic layers, and physical mechanisms

    Science.gov (United States)

    Rapp, Markus; Leitert, Lasse; Latteck, Ralph; Zecha, Marius; Hoffmann, Peter; Höffner, Josef; Hoppe, Ulf-Peter; La Hoz, Cesar

    For more than ten years the Leibniz-Institute of Atmospheric Physics at Rostock University in Kühlungsborn has been operating two VHF-radars (53.5 MHz) at the Arctic location Andenes (69N, 16E) as well as the mid-latitude site Kühlungsborn (54.1N 11.8E). Both radars have primarily been used for the study of strong radar echoes from the summer mesopause region known as (polar) mesosphere summer echoes or (P)MSE. PMSE occur from mid May until mid August in an altitude range from 80 -90 km, i.e., at the time of year and in the altitude range where the atmosphere is supersaturated with respect to ice such that ice particles may form, modify the D-region plasma, and lead to spectacular radar echoes. The existence of echoes from above this altitude range has generally been deemed impossible since refractive index fluctuations arising from neutral dynamics such as turbulence are effectively destroyed at these altitudes owing to the exponential increase of viscosity with height. Also, plasma instabilities which occur between 90 -110 km height produce field aligned irregularities and should not lead to detectable echoes for vertically sounding radars at polar latitudes where the magnetic field lines are essentially perpendicular to the surface. It hence comes as a surprise that our recent observations in the altitude range from 90 -115 km reveals the presence of strong radar echoes both at 69N as well as 54N. These echoes have a typical duration of less than 1 hour and extend over less than 1 km in height. They occur in the entire altitude range from 90 to 115 km with a pronounced maximum at 100 km. The seasonal variation is marked by a pronounced maximum during the summer months. This paper describes the morphology and statistics of these echoes, discusses its relation to sporadic E-layers and sporadic metal layers, and closes with an initial attempt to identify a physical mechanism responsible for these structures.

  9. Thermophysical Properties of Liquid Te: Density, Electrical Conductivity, and Viscosity

    Science.gov (United States)

    Li, C.; Su, C.; Lehoczky, S. L.; Scripa, R. N.; Ban, H.; Lin, B.

    2004-01-01

    The thermophysical properties of liquid Te, namely, density, electrical conductivity, and viscosity, were determined using the pycnometric and transient torque methods from the melting point of Te (723 K) to approximately 1150 K. A maximum was observed in the density of liquid Te as the temperature was increased. The electrical conductivity of liquid Te increased to a constant value of 2.89 x 10(exp 5 OMEGA-1m-1) as the temperature was raised above 1000 K. The viscosity decreased rapidly upon heating the liquid to elevated temperatures. The anomalous behaviors of the measured properties are explained as caused by the structural transitions in the liquid and discussed in terms of Eyring's and Bachiskii's predicted behaviors for homogeneous liquids. The Properties were also measured as a function of time after the liquid was coded from approximately 1173 or 1123 to 823 K. No relaxation phenomena were observed in the properties after the temperature of liquid Te was decreased to 823 K, in contrast to the relaxation behavior observed for some of the Te compounds.

  10. Electrical transport properties of manganite powders under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M.G. [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN, UBA, and IFIBA (CONICET), Ciudad Universitaria, (C1428EHA) Buenos Aires (Argentina); Leyva, A.G. [Gerencia de Investigacion y Aplicaciones, CAC, Comision Nacional de Energia Atomica, Gral Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Acha, C., E-mail: acha@df.uba.ar [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN, UBA, and IFIBA (CONICET), Ciudad Universitaria, (C1428EHA) Buenos Aires (Argentina)

    2012-08-15

    We have measured the electrical resistance of micrometric to nanometric powders of the La{sub 5/8-y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (LPCMO with y=0.3) manganite for hydrostatic pressures up to 4 kbar. By applying different final thermal treatments to samples synthesized by a microwave assisted denitration process, we obtained two particular grain characteristic dimensions (40 nm and 1000 nm) which allowed us to analyze the grain size sensitivity of the electrical conduction properties of both the metal electrode interface with manganite (Pt/LPCMO) and the intrinsic intergranular interfaces formed by the LPCMO powder, conglomerate under the only effect of external pressure. We also analyzed the effects of pressure on the phase diagram of these powders. Our results indicate that different magnetic phases coexist at low temperatures and that the electrical transport properties are related to the intrinsic interfaces, as we observe evidences of a granular behavior and an electronic transport dominated by the Space Charge limited Current mechanism.

  11. Electrical Properties of Polytypic Mg Doped GaAs Nanowires

    Directory of Open Access Journals (Sweden)

    N. Cifuentes

    2016-01-01

    Full Text Available The electrical transport properties of individual Mg doped GaAs nanowires are investigated. It is shown that Mg can be successfully used as a nontoxic p-type dopant in GaAs nanowires. The doping levels, expanding over two orders of magnitude, and free holes mobility in the NW were obtained by the analysis of field effect transistors transfer curves. The temperature dependence of the electrical resistivity above room temperature shows that the polytypic structure of the NWs strongly modifies the NWs charge transport parameters, like the resistivity activation energy and holes mobility. At lower temperatures the NWs exhibit variable range hopping conduction. Both Mott and Efros-Shklovskii variable range hopping mechanisms were clearly identified in the nanowires.

  12. The Influence of Sand Grains Properties on Electrical Properties of Moulding Sand with Inorganic Binder

    Directory of Open Access Journals (Sweden)

    Opyd B.

    2015-09-01

    Full Text Available The paper presents the results of basic research on the influence of the properties of sand grains on electrical properties of water glass moulding sands. It shows electrical properties of the main component – sand grains, crucial to the kinetics of moulding sands heating, such as permittivity εr and loss factor tgδ. Measurements were carried out with the use of the perturbation method for silica, chromite and olivine sands of different mineral, chemical composition and particle size distribution, as well as for moulding sands with water glass grade 145. Analysis of the results of measurements of electrical properties shows that all moulding sands are characterized by a similar permittivity εr and loss factor tgδ. It was found that the electrical properties and the quantity and quality of other components may have a decisive influence on the effectiveness and efficiency of the microwave heating of moulding sands with sand grains. In determining the ability to efficiently absorb the microwave radiation for mixtures which moulding sands are, the impact of all components influencing their individual technological parameters should be taken into account.

  13. Electrical properties of methane hydrate + sediment mixtures

    Science.gov (United States)

    Du Frane, Wyatt L.; Stern, Laura A.; Constable, Steven; Weitemeyer, Karen A.; Smith, Megan M; Roberts, Jeffery J.

    2015-01-01

    Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. Toward this goal, we built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EM field surveys. Here we report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. These results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.

  14. Ultimate VHF Broadband Interferometer Zen KAWASAKI and Manabu AKITA

    Science.gov (United States)

    Kawasaki, Z.; Akita, M.

    2013-12-01

    Lightning Research Group of Osaka University (LRGOU) has been developing an interferometer for thunderstorm monitoring during these two decades. When LRGOU initiated this project, many related scientists claimed that LRGOU's system was a time of arrival and it must be a sophisticated TOA system. However the key technology of the system were broad band and digital data processing, and it is named the VHF broad band digital interferometer (BDITF), because the phase difference of Fourier components played the very important role. Then the BDITF finally has been realized as a quasi-real time lightning monitoring system, and LRGOU has been operating their BDITFs around Osaka area. Since the BDITF captures the VHF impulses associated with lightning discharges by amplitude triggering, it occasionally misses one of the bi-directional leader progressions because of relatively small amplitude VHF impulses mainly emitted by positive leader tips. All of high density of VHF pulses associated with recoil leaders may not be recorded. Then the ordinary BDITF is able to be accepted as the practical operational system, but from the aspect of science it has been sioriously expected to be improved its performance. To overcome the difficulty New Mexico Institute of Mining and Technology (NMIMT) and LRGOU have started the joint project, and a continuous recording system for digital signals is adopted [M. Stock et al, and M Akita et al,]. The field campaigns have been conducting in New Mexico and in Japan, and successful observations are accomplished. The algorithm to identify individual VHF pulses associated with lightning discharges from back ground noise and/or artificial noise, the dispersion of phase differences for all Fourier components is examined. In case by of small dispersion it is concluded that analyzed VHF pulse has high possibility to be emitted by lightning discharges. This interpretation means that the recorded VHF pulse shape might maintain without deformation during

  15. Applications for Electrical Impedance Tomography (EIT) and Electrical Properties of the Human Body.

    Science.gov (United States)

    Lymperopoulos, Georgios; Lymperopoulos, Panagiotis; Alikari, Victoria; Dafogianni, Chrisoula; Zyga, Sofia; Margari, Nikoletta

    2017-01-01

    Electrical Impedance Tomography (EIT) is a promising application that displays changes in conductivity within a body. The basic principle of the method is the repeated measurement of surface voltages of a body, which are a result of rolling injection of known and small-volume sinusoidal AC current to the body through the electrodes attached to its surface. This method finds application in biomedicine, biology and geology. The objective of this paper is to present the applications of Electrical Impedance Tomography, along with the method's capabilities and limitations due to the electrical properties of the human body. For this purpose, investigation of existing literature has been conducted, using electronic databases, PubMed, Google Scholar and IEEE Xplore. In addition, there was a secondary research phase, using paper citations found during the first research phase. It should be noted that Electrical Impedance Tomography finds use in a plethora of medical applications, as the different tissues of the body have different conductivities and dielectric constants. Main applications of EIT include imaging of lung function, diagnosis of pulmonary embolism, detection of tumors in the chest area and diagnosis and distinction of ischemic and hemorrhagic stroke. EIT advantages include portability, low cost and safety, which the method provide, since it is a noninvasive imaging method that does not cause damage to the body. The main disadvantage of the method, which blocks its wider spread, appears in the image composition from the voltage measurements, which are conducted by electrodes placed on the periphery of the body, because the injected currents are affected nonlinearly by the general distribution of the electrical properties of the body. Furthermore, the complex impedance of the skin-electrode interface can be modelled by using a capacitor and two resistor, as a result of skin properties. In conclusion, Electrical Impedance Tomography is a promising method for the

  16. Vanadium Doped Tungsten Oxide Material - Electrical Physical and Sensing Properties

    Directory of Open Access Journals (Sweden)

    Shishkin N. Y.

    2008-05-01

    Full Text Available The electrical physical and sensing (to VOCs and inorganic gases properties of vanadium doped tungsten oxide in the regions of phase transition temperature were investigated. Vanadium oxide (II dimerization was observed in the doped material, corresponding to new phase transition. The extreme sensitivity and selectivity to chemically active gases and vapors in small concentrations: CO, NOx, NH3 acetone, ethanol near phase transitions temperature was found. Sensor elements were manufactured for the quantitative detection (close to 1 ppm of alcohol and ammonia.

  17. Influence of electrical sheet width on dynamic magnetic properties

    CERN Document Server

    Chevalier, T; Cornut, B

    2000-01-01

    Effects of the width of electrical steel sheets on dynamic magnetic properties are investigated by solving diffusion equation on the cross-section of the sheet. Linear and non-linear cases are studied, and are compared with measurement on Epstein frame. For the first one an analytical solution is found, while for the second, a 2D finite element simulation is achieved. The influence of width is highlighted for a width thickness ratio lower than 10. It is shown that the behaviour modification in such cases is conditioned by the excitation signal waveform, amplitude and also frequency.

  18. Electrical Transport Properties of Carbon Nanotube Metal-Semiconductor Heterojunction

    Science.gov (United States)

    Talukdar, Keka; Shantappa, Anil

    2016-10-01

    Carbon nanotubes (CNTs) have been proved to have promising applicability in various fields of science and technology. Their fascinating mechanical, electrical, thermal, optical properties have caught the attention of today’s world. We have discussed here the great possibility of using CNTs in electronic devices. CNTs can be both metallic and semiconducting depending on their chirality. When two CNTs of different chirality are joined together via topological defects, they may acquire rectifying diode property. We have joined two tubes of different chiralities through circumferential Stone-Wales defects and calculated their density of states by nearest neighbor tight binding approximation. Transmission function is also calculated to analyze whether the junctions can be used as electronic devices. Different heterojunctions are modeled and analyzed in this study. Internal stresses in the heterojunctions are also calculated by molecular dynamics simulation.

  19. Research on lunar materials. [optical, chemical, and electrical properties

    Science.gov (United States)

    Gold, T.

    1978-01-01

    Abstracts of 14 research reports relating to investigations of lunar samples are presented. The principal topics covered include: (1) optical properties of surface and core samples; (2) chemical composition of the surface layers of lunar grains: Auger electron spectroscopy of lunar soil and ground rock samples; (3) high frequency electrical properties of lunar soil and rock samples and their relevance for the interpretation of lunar radar observations; (4) the electrostatic dust transport process; (5) secondary electron emission characteristics of lunar soil samples and their relevance to the dust transportation process; (6) grain size distribution in surface soil and core samples; and (7) the optical and chemical effects of simulated solar wind (2keV proton and a particle radiation) on lunar material.

  20. Electric and magnetic properties of PMMA/manganite composites

    Energy Technology Data Exchange (ETDEWEB)

    Artale, C.; Fermepin, S. [GAIyANN, GIA, Centro Atomico Constituyentes, CNEA, Av. Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); Departamento de Fisica, FCEN, UBA, Buenos Aires (Argentina); Forti, M.; Latino, M. [GAIyANN, GIA, Centro Atomico Constituyentes, CNEA, Av. Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); Instituto de Tecnologia ' J.A. Sabato' , UNSAM-CNEA, San Martin, Prov. de Buenos Aires (Argentina); Quintero, M.; Granja, L. [GAIyANN, GIA, Centro Atomico Constituyentes, CNEA, Av. Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); CONICET, Buenos Aires (Argentina); Sacanell, J., E-mail: sacanell@cnea.gov.a [GAIyANN, GIA, Centro Atomico Constituyentes, CNEA, Av. Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); CONICET, Buenos Aires (Argentina); Polla, G. [GAIyANN, GIA, Centro Atomico Constituyentes, CNEA, Av. Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); Levy, P. [GAIyANN, GIA, Centro Atomico Constituyentes, CNEA, Av. Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); CONICET, Buenos Aires (Argentina)

    2009-10-01

    We present the synthesis and characterization of the La{sub 2/3}Sr{sub 1/3}MnO{sub 3} manganite in the form of tapes using polymethyl methacrylate (PMMA) as binder. We have studied their electric and magnetic properties as a function of temperature and magnetic field. The magnetization results have been shown to be dominated by the intrinsic magnetic properties of the manganite. Resistivity measurements showed an insulating behavior in the whole range of temperatures measured, indicating that the percolation threshold of manganite grains has not been reached even for the sample with 35% of PMMA relative content. The obtained magnetoresistance is largest in the sample with 35% of PMMA relative content.

  1. Electrical and optoelectronic properties of two-dimensional materials

    Science.gov (United States)

    Wang, Qiaoming

    Electrical and optoelectronic properties of bulk semiconductor materials have been extensively explored in last century. However, when reduced to one-dimensional and two-dimensional, many semiconductors start to show unique electrical and optoelectronic behaviors. In this dissertation, electrical and optoelectronic properties of one-dimensional (nanowires) and two-dimensional semiconductor materials are investigated by various techniques, including scanning photocurrent microscopy, scanning Kelvin probe microscopy, Raman spectroscopy, photoluminescence, and finite-element simulations. In our work, gate-tunable photocurrent in ZnO nanowires has been observed under optical excitation in the visible regime, which originates from the nanowire/substrate interface states. This gate tunability in the visible regime can be used to enhance the photon absorption efficiency, and suppress the undesirable visible-light photodetection in ZnO-based solar cells. The power conversion efficiency of CuInSe2/CdS core-shell nanowire solar cells has been investigated. The highest power conversion efficiency per unit area/volume is achieved with core diameter of 50 nm and the thinnest shell thickness. The existence of the optimal geometrical parameters is due to a combined effect of optical resonances and carrier transport/dynamics. Significant current crowding in two-dimensional black phosphorus field-effect transistors has been found, which has been significantly underestimated by the commonly used transmission-line model. This current crowding can lead to Joule heating close to the contacts. New van der Waals metal-semiconductor junctions have been mechanically constructed and systematically studied. The photocurrent on junction area has been demonstrated to originate from the photothermal effect rather than the photovoltaic effect. Our findings suggest that a reasonable control of interface/surface state properties can enable new and beneficial functionalities in nanostructures. We

  2. Optical and electrical properties of negatively charged aluminium oxynitride films

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Kyungsoo; Jung, Sungwook; Lee, Jeoungin; Lee, Kwangsoo; Kim, Jaehong; Son, Hyukjoo [School of information and communication Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, 440-746 (Korea, Republic of); Yi, Junsin [School of information and communication Engineering, Sungkyunkwan University, 300 Chunchun-dong, Jangan-gu, Suwon, 440-746 (Korea, Republic of)], E-mail: yi@yurim.ac.kr

    2008-11-03

    Aluminium oxynitride (AlON) thin films were deposited by Radio Frequency (RF) magnetron sputtering on n-type silicon (Si) substrate of (100) orientation using argon (Ar) and oxygen (O{sub 2}) gases at substrate temperature of 450 {sup o}C. To know the change in electrical properties with gases ratio, a deposition was carried out for 140 s with Ar:O{sub 2} ratio changed from 1:3 to 4:3. After that, electrical properties of Metal-Insulator-Semiconductor (MIS) structure with AlON was analyzed. For Ar:O{sub 2} ratios from 1:3 to 4:3, all samples showed characteristics of negative charge. In particular, when Ar:O{sub 2} were 2:3 and 3:3, the value of flatband voltage in normal C-V curve showed above 14 V. The composition of the AlON in the film was investigated using X-ray Photoelectron Spectroscopy (XPS). The flatband voltages (V{sub FB}) in C-V curves were found to depend on compositions. The characteristics of photon energy band gap were obtained by UV/VIS spectrum.

  3. Electrical Properties of Nanoscale ZnS Thin Film Transistor

    Directory of Open Access Journals (Sweden)

    Teresa Oh

    2015-01-01

    Full Text Available To understand the contact mechanism from electrical properties of the ZnS TFTs, ZnS was fabricated on SiOC as a gate insulator on a Si substrate. Ohmic contact without a potential barrier increased the leakage current, but Schottky contact decreased the leakage current because of a Schottky barrier (SB. The ZnS TFTs prepared on SiOC with a Schottky contact improved the stability with respect to the reduction of drain voltages. The structural matching between ZnS and SiOC increased the height of SB such as ZnS annealed at 200°C, which made ZnS become an amorphous structure. ZnS/SiOC films with a low SB increased the capacitance and leakage current. The crystallinity orientation of ZnS localized defect states and the drift current owing to the impurity charge carriers caused the leakage current through low SB near zero voltages. But the increment of diffusion currents in a depletion layer increased the SB and then decreased the leakage current. So the electrical properties of devices were improved by a tunneling effect of diffusion currents.

  4. Electrical Properties of Self-Assembled Nano-Schottky Diodes

    Directory of Open Access Journals (Sweden)

    F. Ruffino

    2008-01-01

    Full Text Available A bottom-up methodology to fabricate a nanostructured material by Au nanoclusters on 6H-SiC surface is illustrated. Furthermore, a methodology to control its structural properties by thermal-induced self-organization of the Au nanoclusters is demonstrated. To this aim, the self-organization kinetic mechanisms of Au nanoclusters on SiC surface were experimentally studied by scanning electron microscopy, atomic force microscopy, Rutherford backscattering spectrometry and theoretically modelled by a ripening process. The fabricated nanostructured materials were used to probe, by local conductive atomic force microscopy analyses, the electrical properties of nano-Schottky contact Au nanocluster/SiC. Strong efforts were dedicated to correlate the structural and electrical characteristics: the main observation was the Schottky barrier height dependence of the nano-Schottky contact on the cluster size. Such behavior was interpreted considering the physics of few electron quantum dots merged with the concepts of ballistic transport and thermoionic emission finding a satisfying agreement between the theoretical prediction and the experimental data. The fabricated Au nanocluster/SiC nanocontact is suggested as a prototype of nano-Schottky diode integrable in complex nanoelectronic circuits.

  5. VHF signal power suppression in stratiform and convective precipitation

    Directory of Open Access Journals (Sweden)

    A. J. McDonald

    2006-03-01

    Full Text Available Previous studies have indicated that VHF clear-air radar return strengths are reduced during periods of precipitation. This study aims to examine whether the type of precipitation, stratiform and convective precipitation types are identified, has any impact on the relationships previously observed and to examine the possible mechanisms which produce this phenomenon. This study uses a combination of UHF and VHF wind-profiler data to define periods associated with stratiform and convective precipitation. This identification is achieved using an algorithm which examines the range squared corrected signal to noise ratio of the UHF returns for a bright band signature for stratiform precipitation. Regions associated with convective rainfall have been defined by identifying regions of enhanced range corrected signal to noise ratio that do not display a bright band structure and that are relatively uniform until a region above the melting layer.

    This study uses a total of 68 days, which incorporated significant periods of surface rainfall, between 31 August 2000 and 28 February 2002 inclusive from Aberystwyth (52.4° N, 4.1° W. Examination suggests that both precipitation types produce similar magnitude reductions in VHF signal power on average. However, the frequency of occurrence of statistically significant reductions in VHF signal power are very different. In the altitude range 2-4 km stratiform precipitation is related to VHF signal suppression approximately 50% of the time while in convective precipitation suppression is observed only 27% of the time. This statistical result suggests that evaporation, which occurs more often in stratiform precipitation, is important in reducing the small-scale irregularities in humidity and thereby the radio refractive index. A detailed case study presented also suggests that evaporation reducing small-scale irregularities in humidity may contribute to the observed VHF signal

  6. VHF signal power suppression in stratiform and convective precipitation

    Directory of Open Access Journals (Sweden)

    A. J. McDonald

    2006-03-01

    Full Text Available Previous studies have indicated that VHF clear-air radar return strengths are reduced during periods of precipitation. This study aims to examine whether the type of precipitation, stratiform and convective precipitation types are identified, has any impact on the relationships previously observed and to examine the possible mechanisms which produce this phenomenon. This study uses a combination of UHF and VHF wind-profiler data to define periods associated with stratiform and convective precipitation. This identification is achieved using an algorithm which examines the range squared corrected signal to noise ratio of the UHF returns for a bright band signature for stratiform precipitation. Regions associated with convective rainfall have been defined by identifying regions of enhanced range corrected signal to noise ratio that do not display a bright band structure and that are relatively uniform until a region above the melting layer. This study uses a total of 68 days, which incorporated significant periods of surface rainfall, between 31 August 2000 and 28 February 2002 inclusive from Aberystwyth (52.4° N, 4.1° W. Examination suggests that both precipitation types produce similar magnitude reductions in VHF signal power on average. However, the frequency of occurrence of statistically significant reductions in VHF signal power are very different. In the altitude range 2-4 km stratiform precipitation is related to VHF signal suppression approximately 50% of the time while in convective precipitation suppression is observed only 27% of the time. This statistical result suggests that evaporation, which occurs more often in stratiform precipitation, is important in reducing the small-scale irregularities in humidity and thereby the radio refractive index. A detailed case study presented also suggests that evaporation reducing small-scale irregularities in humidity may contribute to the observed VHF signal suppression.

  7. Properties of electric turbulence in the polar cap ionosphere

    Science.gov (United States)

    Golovchanskaya, I. V.; Kozelov, B. V.

    2010-10-01

    Small-scale (scales of ˜0.5-256 km) electric fields in the polar cap ionosphere are studied on the basis of measurements of the Dynamics Explorer 2 (DE-2) low-altitude satellite with a polar orbit. Nineteen DE-2 passes through the high-latitude ionosphere from the morning side to the evening side are considered when the IMF z component was southward. A rather extensive polar cap, which could be identified using the ɛ- t spectrograms of precipitating particles with auroral energies, was formed during the analyzed events. It is shown that the logarithmic diagrams (LDs), constructed using the discrete wavelet transform of electric fields in the polar cap, are power law (μ ˜ s α). Here, μ is the variance of the detail coefficients of the signal discrete wavelet transform, s is the wavelet scale, and index α characterizes the LD slope. The probability density functions P(δ E, s) of the electric field fluctuations δ E observed on different scales s are non-Gaussian and have intensified wings. When the probability density functions are renormalized, that is constructed of δ E/ s γ, where γ is the scaling exponent, they lie near a single curve, which indicates that the studied fields are statistically self-similar. In spite of the fact that the amplitude of electric fluctuations in the polar cap is much smaller than in the auroral zone, the quantitative characteristics of field scaling in the two regions are similar. Two possible causes of the observed turbulent structure of the electric field in the polar cap are considered: (1) the structure is transferred from the solar wind, which is known to have turbulent properties, and (2) the structure is generated by convection velocity shears in the region of open magnetic field lines. The detected dependence of the characteristic distribution of turbulent electric fields over the polar cap region on IMF B y and the correlation of the rms amplitudes of δ E fluctuations with IMF B z and the solar wind transfer

  8. Mapping the electrical properties of large-area graphene

    Science.gov (United States)

    Bøggild, Peter; Mackenzie, David M. A.; Whelan, Patrick R.; Petersen, Dirch H.; Due Buron, Jonas; Zurutuza, Amaia; Gallop, John; Hao, Ling; Jepsen, Peter U.

    2017-12-01

    The significant progress in terms of fabricating large-area graphene films for transparent electrodes, barriers, electronics, telecommunication and other applications has not yet been accompanied by efficient methods for characterizing the electrical properties of large-area graphene. While in the early prototyping as well as research and development phases, electrical test devices created by conventional lithography have provided adequate insights, this approach is becoming increasingly problematic due to complications such as irreversible damage to the original graphene film, contamination, and a high measurement effort per device. In this topical review, we provide a comprehensive overview of the issues that need to be addressed by any large-area characterisation method for electrical key performance indicators, with emphasis on electrical uniformity and on how this can be used to provide a more accurate analysis of the graphene film. We review and compare three different, but complementary approaches that rely either on fixed contacts (dry laser lithography), movable contacts (micro four point probes) and non-contact (terahertz time-domain spectroscopy) between the probe and the graphene film, all of which have been optimized for maximal throughput and accuracy, and minimal damage to the graphene film. Of these three, the main emphasis is on THz time-domain spectroscopy, which is non-destructive, highly accurate and allows both conductivity, carrier density and carrier mobility to be mapped across arbitrarily large areas at rates that by far exceed any other known method. We also detail how the THz conductivity spectra give insights on the scattering mechanisms, and through that, the microstructure of graphene films subject to different growth and transfer processes. The perspectives for upscaling to realistic production environments are discussed.

  9. Comparison of mechanical properties for several electrical spring contact alloys

    Energy Technology Data Exchange (ETDEWEB)

    Nordstrom, Terry V.

    1976-06-01

    Work was conducted to determine whether beryllium-nickel alloy 440 had mechanical properties which made it suitable as a substitute for the presently used precious metal contact alloys Paliney 7 and Neyoro G, in certain electrical contact applications. Possible areas of applicability for the alloy were where extremely low contact resistance was not necessary or in components encountering elevated temperatures above those presently seen in weapons applications. Evaluation of the alloy involved three major experimental areas: 1) measurement of the room temperature microplastic (epsilon approximately 10/sup -6/) and macroplastic (epsilon approximately 10/sup -3/) behavior of alloy 440 in various age hardening conditions, 2) determination of applied stress effects on stress relaxation or contact force loss and 3) measurement of elevated temperature mechanical properties and stress relaxation behavior. Similar measurements were also made on Neyoro G and Paliney 7 for comparison. The primary results of the study show that beryllium-nickel alloy 440 is from a mechanical properties standpoint, equal or superior to the presently used Paliney 7 and Neyoro G for normal Sandia requirements. For elevated temperature applications, alloy 440 has clearly superior mechanical properties.

  10. Structural, electrical and thermoelectric properties of chromium silicate thin films

    Science.gov (United States)

    Abd El Qader, Makram

    2011-12-01

    Thermoelectric devices can generate electrical power as a result of their ability to produce electrical currents in the presence of thermal gradients. They can also produce refrigerative cooling when electrical power is supplied to them. Among the potential semiconducting silicides, CrSi 2 is attractive because of its high thermal and chemical stability and its potential for thermoelectric application. CrSi2/SiO2 thin-film structures were prepared using RF sputtering. As deposited and annealed (300°C to 600°C) thin films were characterized for their structural, electrical, and thermoelectric transport properties. As-sputtered CrSi 2 film is amorphous at room temperature and crystallizes around 300°C independent of thickness. Resistivity of the as-deposited 1im films is 1.20 mO-cm, whereas, the annealed films were not electrically conducting as a result of the formation of cracks in the film. The measured Seebeck voltage of the 1im films is markedly enhanced upon annealing and reaches a value of 81muV/K; close to that of bulk CrSi2. The 0.1mum-thick film exhibit an increase in the resistivity up to 0.9mO-cm upon annealing at 300°C, which drops for higher temperature anneals. This behavior is not well-understood. The Seebeck voltages of the 0.1mum thin films increase with annealing temperatures, reaching a maximum value of 62muV/K. Thermoelectric power factors for 0.1 mum thin films exhibit a similar behavior to that of the Seebeck coefficients; increasing with temperature and reaching a plateau value of 10-3 W/(K2 m) at around 400°C to 450°C. These results suggest that annealed thin films of thicknesses in the range of 0.1mum are more suitable for device applications when glass substrates are employed. In order a deposit ternary and higher order alloys, a three gun sputtering system was designed, built and tested for its level of vacuum levels and cleanliness. The tests showed that the three-gun sputtering system is of vacuum levels of 10-9 Torr and shows

  11. Evaluation of electric properties of cement mortars containing pozzolans

    Directory of Open Access Journals (Sweden)

    Cruz, J. M.

    2011-03-01

    Full Text Available In this paper the evolution of the microstructure of Portland cement mortar is analyzed, by using electrical impedance measurements. Cement mortars are compared without and with two pozzolanic substitutions: spent fluid catalytic cracking catalyst (FCC and metakaolin (MK. The measurement method is described and the model for analyzing the electrical impedance spectra is developed. Three electrical parameters are defined: electrical resistivity, capacitance exponent, and capacitive factor. The results show a significant increase in resistivity of the mortars with pozzolans after 7 days of curing, especially in mortars with MK. This increase is correlated with lime-fixing by the pozzolans. The capacitive properties evolve differently at early age, but reach the same values after 148 days. The electrical and mineralogical data show that the evolution of the microstructure in the mortar with MK starts before it does in the mortars with FCC and that the final microstructure becomes different.

    En este trabajo se analiza la microestructura de morteros de cemento Portland, mediante medidas de impedancia eléctrica. Se comparan morteros de cemento sin y con dos sustituciones puzolánicas: residuo de catalizador de craqueo catalítico (FCC y metacaolín (MK. Se describe el método de medida y se desarrolla el modelo de análisis de los espectros de impedancia eléctrica. Se definen tres parámetros eléctricos: resistividad eléctrica, exponente capacitivo, y factor capacitivo. Se observa un aumento importante de la resistividad de los morteros con puzolana a partir de los 7 días de curado, sobre todo en morteros con MK. Este aumento está correlacionado con la fijación de cal de las puzolanas. Las propiedades capacitivas son diferentes a edad temprana, pero se igualan a los 148 días. Los resultados eléctricos y mineralógicos muestran que la evolución microestructural comienza antes en los morteros con MK que con FCC y que la microestructura

  12. Crystal chemistry and electrical properties of the delafossite structure

    Energy Technology Data Exchange (ETDEWEB)

    Marquardt, Meagen A. [Materials Science and Engineering Department, Iowa State University, 2220 Hoover Hall Ames, IA 50011 (United States); Ashmore, Nathan A. [Materials Science and Engineering Department, Iowa State University, 2220 Hoover Hall Ames, IA 50011 (United States); Cann, David P. [Materials Science and Engineering Department, Iowa State University, 2220 Hoover Hall Ames, IA 50011 (United States)]. E-mail: BaTiO3@iastate.edu

    2006-02-01

    Over the past few decades, the field of transparent conducting oxides has undergone tremendous advances. With the rapid growth of optoelectronic applications related to display technologies, traditional materials such as Sn-doped indium oxide (ITO) are now widely used as transparent electrodes. In addition, with the advent of p-type transparent conductors, through the transparent pn-junction building block, a wide range of functional transparent optoelectronic devices have been demonstrated including UV-emitting diodes, UV-detectors, and transparent thin film transistors. This paper will highlight the unique characteristics of oxide materials based on the delafossite structure with a focus on the interrelationship between the chemistry, crystal structure, process conditions, and electrical and optical properties. The delafossite structure (ABO{sub 2}) is characterized by a layer of linearly coordinated A cations stacked between edge-shared octahedral layers (BO{sub 6}). The A-site cation is comprised of Pt, Pd, Ag, or Cu ions nominally in a monovalent state. The B-site cation can consist of most trivalent transition metals, group III elements, rare earths, or charge compensated pairs (e.g. B{sup 2+}/B{sup 4+}). This layered structure leads to highly anisotropic physical properties. The crystal chemistry of the delafossite structure will be discussed in reference to phase stability, the stability of dopants, and the important physical properties such as the conductivity and optical transparency.

  13. PMSE strength during enhanced D region electron densities: Faraday rotation and absorption effects at VHF frequencies

    Science.gov (United States)

    Chau, Jorge L.; Röttger, Jürgen; Rapp, Markus

    2014-10-01

    In this paper we study the effects of absorption and Faraday rotation on measurements of polar mesosphere summer echoes (PMSE). We found that such effects can produce significant reduction of signal-to-noise ratio (SNR) when the D region electron densities (Ne) are enhanced, and VHF radar systems with linearly polarized antennas are used. In particular we study the expected effects during the strong solar proton event (SPE) of July 2000, also known as the Bastille day flare event. During this event, a strong anti-correlation between the PMSE SNR and the D-region Ne was found over three VHF radar sites at high latitudes: Andøya, Kiruna, and Svalbard. This anti-correlation has been explained (a) in terms of transport effects due to strong electric fields associated to the SPE and (b) due to a limited amount of aerosol particles as compared to the amount of D-region electrons. Our calculations using the Ne profiles used by previous researchers explain most, if not all, of the observed SNR reduction in both time (around the SPE peak) and altitude. This systematic effect, particularly the Faraday rotation, should be recognized and tested, and possibly avoided (e.g., using circular polarization), in future observations during the incoming solar maximum period, to contribute to the understanding of PMSE during enhanced D region Ne.

  14. Investigation of structural and electrical properties of mixed ferrite system

    Energy Technology Data Exchange (ETDEWEB)

    Astik, Nidhi M., E-mail: nidhiastik2002@gmail.com; Jha, Prafulla K., E-mail: prafullaj@yahoo.com [Department of Physics, Faculty of Science, The M. S. University of Baroda, Vadodara (Gujarat) (India)

    2015-05-15

    In the present work, structural and electrical properties of mixed ferrite systems are studied. As prepared compound of Co{sub 0.85}Ca{sub 0.15-y}Cd{sub y}Fe{sub 2}O{sub 4} (y=0.10, 0.15) is synthesized in polycrystalline form, using the stoichiometric mixture of oxides with conventional standard ceramic route with double sintering at 950°C and 1100°C and characterized by X-ray diffraction. The X-ray diffraction pattern confirms the presence of cubic (FCC) structure. The sharp intensified peaks in X-ray diffraction pattern clearly indicate the completeness of reaction.

  15. Electrical properties of Al-, Cu-, Zn- rice husk charcoal junctions

    Science.gov (United States)

    Dahonog, L. A.; Tapia, A. K. G.

    2017-04-01

    Rice husk in the Philippines is considered as an agricultural waste. In order to utilize the material, one common technique is to carbonize these rice husks to produce charcoal briquettes. These materials are porous in nature exhibiting electrical properties from carbon structures. In this study, rice husk charcoals (RHC) were deposited on different metal substrates (Al, Cu, Zn) via a simple solution casting method. The deposited RHC on metal substrates was observed using Scanning Electron Microscopy (SEM). The films were characterized using two-point probe technique and the I-V curves were plotted. Al-RHC films appear to deviate from an ohmic behaviour while Zn-RHC and Cu-RHC showed diode-like behaviours.

  16. Polymer nanocomposite dielectric and electrical properties with quantum dots nanofiller

    Science.gov (United States)

    Ahmed, R. M.; Morsi, R. M. M.

    2017-10-01

    Nanocomposite films of different contents of CdSe/ZnS quantum dots nanoparticles embedded in hosting matrix of polyvinyl chloride (PVC) were prepared by simple solution casting method. Electrical and dielectric properties of nanocomposites films were investigated in the temperature range 323-393 (K) and at frequencies (50-2000) kHz. The frequency dependence of AC conductivity was following the universal power law. The values of the frequency exponent, s, revealed that the conduction mechanism at low temperature is considered by small polaron tunneling model, whereas at high temperature, it is related to CBH model. The activation energy values (ΔE) were depending on nanoparticle concentration as well as frequency. Also, X-ray diffraction (XRD) enabled approximately estimating the average particle size of the nanoparticles incorporated in PVC.

  17. Improving the electrical properties of carbon nanotubes with interhalogen compounds.

    Science.gov (United States)

    Janas, Dawid; Milowska, Karolina Z; Bristowe, Paul D; Koziol, Krzysztof K K

    2017-03-02

    The electronic properties of carbon nanostructures such as carbon nanotubes (CNTs) or graphene can easily be tuned by the action of various doping agents. We present an experimental study and numerical analysis of how and why metallic and semiconductive CNTs can be p-doped by exposing them to two interhalogens: iodine monochloride and iodine monobromide. Simple application of these compounds was found to reduce the electrical resistance by as much as 2/3 without causing any unfavorable chemical modification, which could disrupt the highly conductive network of sp(2) carbon atoms. To gain better insight into the underlying mechanism of the observed experimental results, we provide a first principles indication of how interhalogens interact with model metallic (5,5) and semiconductive (10,0) CNTs.

  18. Structural, Optical and Electrical Properties of ITO Thin Films

    Science.gov (United States)

    Sofi, A. H.; Shah, M. A.; Asokan, K.

    2017-11-01

    Transparent and conductive thin films of indium tin oxide were fabricated on glass substrates by the thermal evaporation technique. Tin doped indium ingots with low tin content were evaporated in vacuum (1.33 × 10-7 kpa) followed by an oxidation for 15 min in the atmosphere in the temperature range of 600-700°C. The structure and phase purity, surface morphology, optical and electrical properties of thin films were studied by x-ray diffractometry and Raman spectroscopy, scanning electron microcopy and atomic force microscopy, UV-visible spectrometry and Hall measurements in the van der Pauw configuration. The x-ray diffraction study showed the formation of the cubical phase of polycrystalline thin films. The morphological analysis showed the formation of ginger like structures and the energy dispersive x-ray spectrum confirmed the presence of indium (In), tin (Sn) and oxygen (O) elements. Hall measurements confirmed n-type conductivity of films with low electrical resistivity (ρ) ˜ 10-3 Ω cm and high carrier concentration (n) ˜ 1020 cm-3. For prevalent scattering mechanisms in the films, experimental data was analyzed by calculating a mean free path (L) using a highly degenerate electron gas model. Furthermore, to investigate the performance of the deposited films as a transparent conductive material, the optical figure of merit was obtained for all the samples.

  19. Structural, Optical and Electrical Properties of ITO Thin Films

    Science.gov (United States)

    Sofi, A. H.; Shah, M. A.; Asokan, K.

    2018-02-01

    Transparent and conductive thin films of indium tin oxide were fabricated on glass substrates by the thermal evaporation technique. Tin doped indium ingots with low tin content were evaporated in vacuum (1.33 × 10-7 kpa) followed by an oxidation for 15 min in the atmosphere in the temperature range of 600-700°C. The structure and phase purity, surface morphology, optical and electrical properties of thin films were studied by x-ray diffractometry and Raman spectroscopy, scanning electron microcopy and atomic force microscopy, UV-visible spectrometry and Hall measurements in the van der Pauw configuration. The x-ray diffraction study showed the formation of the cubical phase of polycrystalline thin films. The morphological analysis showed the formation of ginger like structures and the energy dispersive x-ray spectrum confirmed the presence of indium (In), tin (Sn) and oxygen (O) elements. Hall measurements confirmed n-type conductivity of films with low electrical resistivity ( ρ) ˜ 10-3 Ω cm and high carrier concentration ( n) ˜ 1020 cm-3. For prevalent scattering mechanisms in the films, experimental data was analyzed by calculating a mean free path ( L) using a highly degenerate electron gas model. Furthermore, to investigate the performance of the deposited films as a transparent conductive material, the optical figure of merit was obtained for all the samples.

  20. From VHF to UHF CMOS-MEMS Monolithically Integrated Resonators

    DEFF Research Database (Denmark)

    Teva, Jordi; Berini, Abadal Gabriel; Uranga, A.

    2008-01-01

    This paper presents the design, fabrication and characterization of microresonators exhibiting resonance frequencies in the VHF and UHF bands, fabricated using the available layers of the standard and commercial CMOS technology, AMS-0.35mum. The resonators are released in a post-CMOS process cons...

  1. Magnetic Resonance Based Electrical Property Tomography (MR-EPT) for Prostate Cancer Grade Imaging

    Science.gov (United States)

    2015-07-01

    AD_________________ Award Number: W81XWH-13-1-0127 TITLE: “Magnetic Resonance-Based Electrical Property Tomography (MR- EPT) for Prostate Cancer...2014 – June 30, 2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER W81XWH-13-1-0127 Magnetic Resonance-Based Electrical Property Tomography (MR- EPT...clinical challenge. This technology development study is focused on developing Magnetic Resonance – Electrical Property Tomography (MR-EPT

  2. Characterization of electrical and optical properties of silicon based materials

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Guobin

    2009-12-04

    In this work, the electrical and luminescence properties of a series of silicon based materials used for photovoltaics, microelectronics and nanoelectronics have been investigated by means of electron beam induced current (EBIC), cathodoluminescence (CL), photoluminescence (PL) and electroluminescence (EL) methods. Photovoltaic materials produced by block casting have been investigated by EBIC on wafers sliced from different parts of the ingot. Various solar cell processings have been compared in parallel wafers by means of EBIC collection efficiency measurements and contrast-temperature C(T) behaviors of the extended defects, i. e. dislocations and grain boundaries (GBs). It was found that the solar cell processing with phosphorus diffusion gettering (PDG) followed with a SiN firing greatly reduces the recombination activity of extended defects at room temperature, and improves the bulk property simultaneously. A remaining activity of the dislocations indicates the limitation of the PDG at extended defects. Abnormal behavior of the dislocation activity after certain solar cell processes was also observed in the region with high dislocation density, the dislocations are activated after certain solar cell processings. In order to evaluate the properties of a thin polycrystalline silicon layer prepared by Al-induced layer exchange (Alile) technique, epitaxially layer grown on silicon substrate with different orientations was used as a model system to investigate the impact by the process temperature and the substrates. EBIC energy dependent collection efficiency measurements reveal an improvement of the epilayer quality with increasing substrate temperature during the growth from 450 C to 650 C, and a decrease of epilayer quality at 700 C. PL measurements on the epitaxially grown Si layer on silicon substrates revealed no characteristic dislocation-related luminescence (DRL) lines at room temperature and 77 K, while in the samples prepared by Alile process, intense

  3. Electrical and optical properties of nickel ferrite/polyaniline nanocomposite

    Directory of Open Access Journals (Sweden)

    M. Khairy

    2015-07-01

    Full Text Available Polyaniline–NiFe2O4 nanocomposites (PANI–NiFe2O4 with different contents of NiFe2O4 (2.5, 5 and 50 wt% were prepared via in situ chemical oxidation polymerization, while the nanoparticles nickel ferrite were synthesized by sol–gel method. The prepared samples were characterized using some techniques such as Fourier transforms infrared (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM and thermogravimetric analysis (TGA. Moreover, the electrical conductivity and optical properties of the nanocomposites were investigated. Pure (PANI and the composites containing 2.5 and 5 wt% NiFe2O4 showed amorphous structures, while the one with 50 wt% NiFe2O4 showed a spinel crystalline structure. The SEM images of the composites showed different aggregations for the different nickel ferrite contents. FTIR spectra revealed to the formation of some interactions between the PANI macromolecule and the NiFe2O4 nanoparticles, while the thermal analyses indicated an increase in the composites stability for samples with higher NiFe2O4 nanoparticles contents. The electrical conductivity of PANI–NiFe2O4 nanocomposite was found to increase with the rise in NiFe2O4 nanoparticle content, probably due to the polaron/bipolaron formation. The optical absorption experiments illustrate direct transition with an energy band gap of Eg = 1.0 for PANI–NiFe2O4 nanocomposite.

  4. Investigation of Thermal and Electrical Properties for Conductive Polymer Composites

    Science.gov (United States)

    Juwhari, Hassan K.; Abuobaid, Ahmad; Zihlif, Awwad M.; Elimat, Ziad M.

    2017-10-01

    This study addresses the effects of temperature ranging from 300 K to 400 K on thermal ( κ) and electrical ( σ) conductivities, and Lorenz number ( L) for different conductive polymeric composites (CPCs), as tailoring the ratios between both conductivities of the composites can be influential in the design optimization of certain thermo-electronic devices. Both κ and σ were found to have either a linear or a nonlinear (2nd and 3rd degree polynomial function) increasing behavior with increased temperatures, depending on the conduction mechanism occurring in the composite systems studied. Temperature-dependent behavior of L tends to show decreasing trends above 300 K, where at 300 K the highest and the lowest values were found to be 3 × 103 W Ω/K2 for CPCs containing iron particles and 3 × 10-2 W Ω/K2 for CPCs-containing carbon fibers respectively. Overall, temperature-dependent behavior of κ/ σ and L can be controlled by heterogeneous structures produced via mechanical-molding-compression. These structures are mainly responsible for energy-transfer processes or transport properties that take place by electrons and phonons in the CPCs' bulks. Hence, the outcome is considered significant in the development process of high performing materials for the thermo-electronic industry.

  5. Structural, thermal, and electrical properties of CrSi2

    Science.gov (United States)

    Dasgupta, T.; Etourneau, J.; Chevalier, B.; Matar, S. F.; Umarji, A. M.

    2008-06-01

    Stoichiometric CrSi2 was prepared by arc melting and compacted by uniaxial hot pressing for property measurements. The crystal structure of CrSi2 was investigated using the powder x-ray diffraction method. From the Rietveld refinement, the lattice parameters were found to be a =4.42757 (7) and c =6.36804 (11)Å, respectively. The thermal expansion measurement revealed an anisotropic expansion in the temperature range from room temperature 800K with αa=14.58×10-6/K, αc=7.51×10-6/K, and αV=12.05×10-6/K. The volumetric thermal expansion coefficient shows an anomalous decrease in the temperature range of 450-600K. The measured electrical resistivity ρ and thermoelectric power S have similar trends with a maxima around 550K. Thermal conductivity measurements show a monotonic decrease with increasing temperature from a room temperature value of 10Wm-1K-1. The ZT values increase with temperature and have a maximum value of 0.18 in the temperature range studied. An analysis of the electronic band structure is provided.

  6. SEARCHING FOR ELECTRICAL PROPERTIES, PHENOMENA AND MECHANISMS IN THE CONSTRUCTION AND FUNCTION OF CHROMOSOMES

    Directory of Open Access Journals (Sweden)

    Ivan Kanev

    2013-03-01

    Full Text Available Our studies reveal previously unidentified electrical properties of chromosomes: (1 chromosomes are amazingly similar in construction and function to electrical transformers; (2 chromosomes possess in their construction and function, components similar to those of electric generators, conductors, condensers, switches, and other components of electrical circuits; (3 chromosomes demonstrate in nano-scale level electromagnetic interactions, resonance, fusion and other phenomena similar to those described by equations in classical physics. These electrical properties and phenomena provide a possible explanation for unclear and poorly understood mechanisms in clinical genetics including: (a electrically based mechanisms responsible for breaks, translocations, fusions, and other chromosomal abnormalities associated with cancer, intellectual disability, infertility, pregnancy loss, Down syndrome, and other genetic disorders; (b electrically based mechanisms involved in crossing over, non-disjunction and other events during meiosis and mitosis; (c mechanisms demonstrating heterochromatin to be electrically active and genetically important.

  7. Effect of Ar bombardment on the electrical and optical properties of ...

    Indian Academy of Sciences (India)

    The influence of low-energy Ar ion beam irradiation on both electrical and optical properties of low-density polyethylene (LDPE) films is presented. The polymer films were bombarded with 320 keV Ar ions with fuences up to 1 × 10 15 cm − 2 . Electrical properties of LDPE films were measured and the effect of ion ...

  8. Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

    OpenAIRE

    Jian Chen; Chengcheng Xue; Yang Zhao; Deyong Chen; Min-Hsien Wu; Junbo Wang

    2015-01-01

    This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance ...

  9. Experimental Enhancement for Electric Properties of Polyethylene Nanocomposites under Thermal Conditions

    Directory of Open Access Journals (Sweden)

    Ahmed Thabet

    2017-01-01

    Full Text Available Polymer properties can be experimentally tailored by adding small amounts of different nanoparticles for enhancing their mechanical, thermal and electrical properties. The work in this paper investigates enhancing the electric and dielectric properties of Low Density Polyethylene (LDPE, and High Density Polyethylene (HDPE polymer materials with cheap nanoparticles. Certain percentages of clay and fumed silica nanoparticles are used to enhance electric and dielectric properties of polyethylene nanocomposites films. By using the Dielectric Spectroscopy; the electric and dielectric properties of each polyethylene nanocomposites have been measured with and without nanoparticles at various frequencies up to 1kHz under different thermal conditions (20°C and 60°C. And so, we were successful in specifying the optimal nanoparticles types and their concentrations for the control of electric and dielectric characterization.

  10. Phase and coherence analysis of VHF scintillation over Christmas Island

    Directory of Open Access Journals (Sweden)

    E. B. Shume

    2014-03-01

    Full Text Available This short paper presents phase and coherence data from the cross-wavelet transform applied on longitudinally separated very high frequency (VHF equatorial ionospheric scintillation observations over Christmas Island. The phase and coherence analyses were employed on a pair of scintillation observations, namely, the east-looking and west-looking VHF scintillation monitors at Christmas Island. Our analysis includes 3 years of peak season scintillation data from 2008, 2009 (low solar activity, and 2011 (moderate solar activity. In statistically significant and high spectral coherence regions of the cross-wavelet transform, scintillation observations from the east-looking monitor lead those from the west-looking monitor by about 20 to 60 (40 ± 20 min (most frequent lead times. Using several years (seasons and solar cycle of lead (or lag and coherence information of the cross-wavelet transform, we envisage construction of a probability model for forecasting scintillation in the nighttime equatorial ionosphere.

  11. Electronic properties of zigzag and armchair graphene nanoribbons in the external electric and magnetic fields

    Science.gov (United States)

    Afshari, F.; Ghaffarian, M.

    2017-05-01

    We explore, numerically, some electronic properties of zigzag and armchair graphene nanoribbons under the external perpendicular magnetic field and transverse electric field. Our results, in the magnetic field only, indicate that numerical Landau levels deviate from the Dirac Landau levels formula for higher levels and quantum Hall conductance curve of armchair nanoribbon shows oscillatory behavior in the high gate voltage. In the presence of transverse electric field only, it is shown that the electric dipole moment of zigzag nanoribbon increases abruptly versus the electric field in the range of low-intensity electric fields while for armchair nanoribbon this varies very slowly. This variation in stronger electric fields is staircase for armchair nanoribbon while it is smoothly for zigzag nanoribbon. In the presence of electric and magnetic fields, there are electrons and holes as charge carrier in the same proportions. Conducting electrons make a round current in the half of nanoribbons while conducting holes make a round current in the other half. Electronic vortices, which are static in the presence of magnetic field only, move along nanoribbons in the effect of the transverse electric field. By considering the curve of electric dipole moment versus the electric field, it is found that magnetic field increases the electric susceptibility of nanoribbons in the low-intensity electric fields substantially and creates considerable electric susceptibilities in several higher electric fields. So these indicate that the magnetic field increases the electric sensitivity of graphene nanoribbons.

  12. Structural, electrical and dielectric properties of yttrium substituted nickel ferrites

    Science.gov (United States)

    Ishaque, M.; Islam, M. U.; Azhar Khan, M.; Rahman, I. Z.; Genson, A.; Hampshire, S.

    2010-03-01

    The influence of Y 3+ substitution on the structural, electrical and dielectric properties of Ni-Y ferrites was studied in the ferrite series NiY 2xFe 2-2xO 4 where x=0-0.12 in steps of 0.02. This series was prepared by conventional double sintering ceramic method. XRD analysis reveals single phase samples up to x=0.06. At x≥0.08, a secondary phase of iron yttrium oxide (YFeO 3) appears along with the spinel phase. The incorporation of Y 3+ for Fe 3+ ions results in a slight increase of lattice constant due to larger ionic radius of the substituted ions. It was inferred that the substitution of yttrium limits the grain growth. The physical densities are about 90% of their X-ray densities. FTIR spectra obtained at room temperature in the wave number range 370-1100 cm -1 show splitting of the two fundamental absorption bands, thereby confirming the completion of solid state reaction. The increase in dc resistivity has been found with the increase in Y 3+ contents. Dielectric constant (ε‧) and loss tangent (tan δ) were measured at room temperature in the frequency range from 10 Hz to10 MHz. A significant reduction in the values of dielectric constant and dielectric loss tangent has been observed with the increase of Y 3+ ions. The high dc resistivity and low dielectric losses are the desired characteristics of Ni-Y ferrites used to prepare microwave devices.

  13. Study of electrical properties of polyvinylpyrrolidone/polyacrylamide ...

    Indian Academy of Sciences (India)

    The permittivity (r) and dielectric loss (i) were found to decrease upon increasing frequency. Temperature and frequency dependence of impedance, relaxation time and electric modulus of thin film samples have also been studied. From electric modulus formalism, polarization and conduction relaxation behaviour in the ...

  14. PMSE Observations With the Tri-Static EISCAT VHF Radars

    Science.gov (United States)

    Mann, I.; Tjulin, A.; Häggström, I.

    2013-12-01

    The polar mesospheric summer echoes (PMSE) are generated in the ionosphere at roughly 80 to 90 altitude by electron irregularities in the presence of charged solid particles and PMSE are most likely observed when ice particles form onto nanodust. PMSE formation is an important part in understanding mesospheric processes, but is also an interesting example for dusty plasma phenomena occurring in space. To investigate the phenomena that lead to formation of PMSE it is helpful to study the radar reflectivity of the mesosphere at different angles. PMSE were previously studied at different aspect angles in order to better understand the scattering process. Another way is observing PMSE from multiple sites simultaneously. During this summer the EISCAT radars that are located in Northern Scandinavia could for the first time be used for tri-static observations in the VHF band and we carried out observations during three subsequent days in June 2013. The radar signal was transmitted in zenith direction with the EISCAT VHF antenna near Tromsø (69.59 deg N, 19.23 deg E) and the scattered signal was measured from Tromsø, Kiruna (67.86 deg N, 20.44 deg E) and Sodankylä (67.36 deg N, 26.63 deg E). Zenith observations were simultaneously carried out with the Tromsø UHF radar (933 MHz). Other groups have previously reported the observations of PMSE simultaneously with the EISCAT VHF and UHF radars, but with a much lower occurrence rate for the UHF. UHF observations made during this campaign are dominated by incoherent scatter. The VHF system in Tromsø detected PMSE for a large fraction of the observation time. The VHF receivers in Kiruna and Sodankylä were pointed at typical PMSE heights above the Tromsø transmitter and detected radar reflections at the same time and altitude as the Tromsø radar. These observations are among the first tri-static observations of PMSE. Preliminary results from the campaign will be presented and discussed.

  15. Extrinsic and intrinsic performance effects on the electrical property in few-layer graphene

    Science.gov (United States)

    Lin, Yow-Jon; Hung, Cheng-Chun; Zeng, Jian-Jhou; Chang, Hsing-Cheng

    2016-02-01

    The effects of extrinsic and intrinsic performances on the electrical property of few-layer graphene (FLG) are investigated. This study uses the ultraviolet irradiation technique to tune the electrical parameters of FLG for analyzing the extrinsic/intrinsic contribution to the electrical conductivity. A correlation between the temperature-dependent electrical properties, phonon and impurity scatterings, and thermal activation of charge carriers is identified. The observed temperature evolution of resistivity is understood from the competition among the effects of phonon and impurity scatterings and thermal activation of charge carriers. It is important to identify the carrier transport behavior for enhancing the FLG-based device performance.

  16. Electrical properties of silver selenide thin films prepared by reactive ...

    Indian Academy of Sciences (India)

    Unknown

    2001-07-29

    805 Å. Keywords. Thin film; silver selenide; reactive evaporation; electrical conductivity. 1. Introduction. Silver selenide attracts the interest of researchers because of its application in the switching devices. The binary and ternary ...

  17. Electrical and optical properties of zinc oxide for scintillator applications

    Science.gov (United States)

    Yang, Xiaocheng

    Zinc oxide (ZnO) is a wide-band-gap semiconductor suitable for many optical and optoelectronic applications. Among these is to use single crystal, powder, or ceramic forms of ZnO as a fast UV scintillator. In this work, the electrical and optical properties of ZnO were studied using photoluminescence, X-ray-induced luminescence, optical absorption, and Hall Effect techniques. This study included single crystal ZnO and ZnO:Ga samples grown from high-pressure-melt (HPM), seeded chemical-vapor-transport (SCVT), and hydrothermal (HYD) techniques; powder samples synthesized using both solution and solid-state processes, and purchased from different commercial sources; and ceramic samples prepared by hot-uni-axial-pressing and spark-plasma-sintering methods. Temperature-dependent PL and Hall measurements were combined to establish the luminescence origins in the n-type ZnO and ZnO:Ga single crystals. Based on a PL line-shape analysis, including band-gap renormalization, the direct (e,h) transition is the main luminescent channel in highly n-type ZnO:Ga, while FX and FX-LO recombinations are responsible for the UV PL from as-grown ZnO. An intrinsic mobility limit for n-type ZnO was established by including three major phonon-scattering mechanisms. Analysis of Hall data from single-crystal samples including both neutral- and ionized-impurity scatterings provided donor and acceptor concentrations and energy levels. High n-type single-crystal ZnO samples prepared either by Ga doping and co-doping, or by after-growth treatments, were also studied. Absorption and reflectance data were used to obtain free carrier concentrations from the Ga-doped and co-doped crystals, and it was found that several samples with n ˜ high-1018 to low-1019 cm -3 had optimum UV luminescence. Anneal treatments in reducing atmospheres increased free carrier concentrations in HPM and HYD samples, but an induced absorption band due to oxygen vacancies limited the UV emission from these samples. PL and

  18. On the Electrical and Magnetic Properties of some Indian Spices

    CERN Document Server

    Baby, Samson K

    2010-01-01

    We have made experimental measurements of electrical conductivity, pH and relative magnetic susceptibility of the aqueous solutions of 24 indian spices. The measured values of electrical conductance of these spices are found to be linearly related to their ash content and bulk calorific values reported in literature. The physiological relevance of the pH and diamagnetic susceptibility of spices when consumed as food or medicine will be also discussed.

  19. Synthesis and enhancing electrical properties of PANI and PPA composites

    Directory of Open Access Journals (Sweden)

    M. Yahia Abed

    2014-09-01

    Full Text Available Polyaniline (PANI was prepared by chemical method using FeCl3 as oxidizing agent. Emeraldine base (EB was prepared using 0.1 M ammonia solution, and redoped using HCl, (±-10-camphorsulfonic acid (CSA and p-toluenesulfonic acid (PTSA. The electrical conductivity of EB was increased by doping. Polyphenylacetylene (PPA and its complexes with KI and NaOEt were prepared and their electrical conductivities were studied. FTIR was used for characterizing the structures.

  20. Relationships between electrical properties and petrography of El-Maghara sandstone formations, Egypt

    Directory of Open Access Journals (Sweden)

    Mohamed A. Kassab

    2017-06-01

    Full Text Available Realization of electrical and petrography of rocks is absolutely necessary for geophysical investigations. The petrographical, petrophysical and electrical properties of sandstone rocks (El-Maghara Formation, North Sinai, Egypt will be discussed in the present work. The goal of this paper was to highlight interrelations between electrical properties in terms of frequency (conductivity, permittivity and impedance and petrography, as well as mineral composition. Electrical properties including (conductivity and dielectric constant were measured at room temperature and humidity of (∼35%. The frequency range used will be from 10 Hz to 100 kHz. Slight changes between samples in electrical properties were found to result from changes in composition and texture. Electrical properties generally change with grain size, shape, sorting, mineralogy and mineral composition. The dielectric constant decreases with frequency and increases with increasing clay content. The conductivity increases with the increase in conductor channels among electrodes. Many parameters can combine together to lead to the same electrical properties. The samples are mainly composed of sand with clay and carbonate.

  1. Relationships between electrical properties and petrography of El-Maghara sandstone formations, Egypt

    Science.gov (United States)

    Kassab, Mohamed A.; Gomaa, Mohamed M.; Lala, Amir M. S.

    2017-06-01

    Realization of electrical and petrography of rocks is absolutely necessary for geophysical investigations. The petrographical, petrophysical and electrical properties of sandstone rocks (El-Maghara Formation, North Sinai, Egypt) will be discussed in the present work. The goal of this paper was to highlight interrelations between electrical properties in terms of frequency (conductivity, permittivity and impedance) and petrography, as well as mineral composition. Electrical properties including (conductivity and dielectric constant) were measured at room temperature and humidity of (∼35%). The frequency range used will be from 10 Hz to 100 kHz. Slight changes between samples in electrical properties were found to result from changes in composition and texture. Electrical properties generally change with grain size, shape, sorting, mineralogy and mineral composition. The dielectric constant decreases with frequency and increases with increasing clay content. The conductivity increases with the increase in conductor channels among electrodes. Many parameters can combine together to lead to the same electrical properties. The samples are mainly composed of sand with clay and carbonate.

  2. Charge Transport and Electrical Properties of Spin Crossover Materials: Towards Nanoelectronic and Spintronic Devices

    OpenAIRE

    Lefter, Constantin; Davesne, Vincent; Salmon, Lionel; Molnar, Gabor; Demont, Philippe; Rotaru, Aurelian; Bousseksou, Azzedine

    2016-01-01

    International audience; In this paper, we present a comprehensive review of research on electrical and charge transport properties of spin crossover complexes. This includes both the effect of spin-state switching on the dielectric permittivity and electrical conductivity of the material and vice versa the influence of an applied electrical field (or current) on the spin-state of the system. The survey covers different size scales from bulk materials and thin films to nanoparticles and single...

  3. Nonlinear Electrical Conductivity Properties of Au Films Prepared by Sputtering

    Directory of Open Access Journals (Sweden)

    Qingyun Meng

    2014-01-01

    Full Text Available Metal-based films with tunable electrical conductivity have played an important role in developing new types of electric devices for future application. In this work, a sputtering method was used to obtain Au films on silicon substrate in a hypobaric atmosphere. Scanning electron microscope (SEM shows that the interspaces between the Au nanoparticles were highly uniform and orderly distributed, with the width of several nanometers at the surface. By measuring the I-V curves of the films with thickness less than 20 nm, the nonlinear behaviors of electrical resistivity became gradually obvious as the decrease of the film thickness. For example, upon the thickness reducing to 10 nm, remarkable discontinuous step phenomenon appeared. Moreover, a computational simulation was carried on the electrical conductivity of films under normal temperature based on the Coulomb blockade theory and scattering theory, in which the electric current was in the range from 0 to 1.5 × 10−5 A. The computational results were consistent well with the experimental observations, which confirm that the nonlinear and step phenomenon can be assigned to the Coulomb blockade effect when electrons transfer occurs in the interspaces between the nanoparticles.

  4. The first operation and results of the Chung-Li VHF radar

    Science.gov (United States)

    Chao, J. K.; Kuo, F. S.; Chu, Y. S.; Fu, I. J.; Rottger, J.; Liu, C. H.

    1986-01-01

    The Chung-Li Very High Frequency (VHF) radar is used in the dual-mode operations, applying Doppler beam-swinging as well as the spaced-antenna-drift method. The design of the VHF radar is examined. Results of performance tests are discussed.

  5. Characterization of dielectric properties of nanocellulose from wood and algae for electrical insulator applications.

    Science.gov (United States)

    Le Bras, David; Strømme, Maria; Mihranyan, Albert

    2015-05-07

    Cellulose is one of the oldest electrically insulating materials used in oil-filled high-power transformers and cables. However, reports on the dielectric properties of nanocellulose for electrical insulator applications are scarce. The aim of this study was to characterize the dielectric properties of two nanocellulose types from wood, viz., nanofibrillated cellulose (NFC), and algae, viz., Cladophora cellulose, for electrical insulator applications. The cellulose materials were characterized with X-ray diffraction, nitrogen gas and moisture sorption isotherms, helium pycnometry, mechanical testing, and dielectric spectroscopy at various relative humidities. The algae nanocellulose sample was more crystalline and had a lower moisture sorption capacity at low and moderate relative humidities, compared to NFC. On the other hand, it was much more porous, which resulted in lower strength and higher dielectric loss than for NFC. It is concluded that the solid-state properties of nanocellulose may have a substantial impact on the dielectric properties of electrical insulator applications.

  6. Responses of electrical properties of tea leaves to low-temperature stress

    National Research Council Canada - National Science Library

    Lu Yongzong; Hu Yongguang; Zhang Xiliang; Li Pingping

    2015-01-01

    .... It changes with complex weather conditions, thus it is difficult to be determined. A method of testing electrical property of tea leaves under cold stress was put forward to indicate critical temperature...

  7. Magnetic Properties of Electrical Steel, Power Transformer Core Losses and Core Design Concepts

    OpenAIRE

    Freitag, Christian

    2017-01-01

    The work presented in this PhD-thesis includes the measurement of electrical steel's properties as well as the simulation of power transformer core losses and leads to the investigation of new core design methods.

  8. Electrical and optical properties of iodide nanoparticles embedded into zeolite porous matrices

    Science.gov (United States)

    Cvetkov, A. V.; Gango, S. E.; Ivanova, M. S.; Khanin, S. D.; Lukin, A. E.; Solovyev, V. G.; Trifonov, S. V.; Veisman, V. L.

    2017-11-01

    Experimental study of the iodine nanoparticles effect on the optical and electrical properties of zeolite - based matrix nanocomposite materials has been carried out. Phase transitions in the nanocomposites under study have been found.

  9. A Study of the Properties of Electrical Insulation Oils and of the Components of Natural Oils

    Directory of Open Access Journals (Sweden)

    Milan Spohner

    2012-01-01

    Full Text Available This paper presents a study of the electrical and non-electrical properties of insulating oils. For the correct choice of an electrical insulation oil, it is necessary to know its density, dynamic viscosity, dielectric constant, loss number and conductivity, and the effects of various exposure factors. This paper deals with mathematical and physical principles needed for studying and making correct measurements of the dynamic viscosity, density and electrical properties of insulation oils. Rheological properties were measured using an A&D SV-10 vibratory viscometer, and analytical balance with density determination kit, which operates on the principle of Archimedes’ law. Dielectric properties were measured using a LCR meter Agilent 4980A with connected with the Agilent 16452A test fixture for dielectric liquids.

  10. Porous and Nonporous Film-Shaped Magnetorheological Nanocomposites: Dielectric and Electrical Properties

    Directory of Open Access Journals (Sweden)

    Aref Naimzad

    2014-01-01

    Full Text Available This paper presents a brief experimental comparative study on electrical and dielectric properties of two sets of porous and nonporous MRNCs, each including five samples of film-shaped magnetorheological nanocomposites (MRNCs based on room temperature vulcanized (RTV silicone rubber and nanosized carbonyl iron particles (CIPs. The electrical and dielectric properties of porous and nonporous MRNCs were measured at five different filler concentrations. Several experiments were performed to measure the volume resistivity, dielectric constant, and dielectric loss. The MRNCs dielectric properties were analysed with respect to the parameters like frequency and CIPs loadings. The electrical conductivity was studied in terms of volume resistivity. The comparative investigation suggests the porous MRNCs for smart and light-weighted structures those benefits from a lower electrical property, dielectric losses, and dielectric constants.

  11. Improved Electrical Properties of Epoxy Resin With Nanometer-Sized Inorganic Fillers (Postprint)

    National Research Council Canada - National Science Library

    Horwath, John C; Schweickart, Daniel L; Garcia, Guido; Klosterman, Donald; Galaska, Mary; Schrand, Amanda; Walko, Lawrence C

    2006-01-01

    .... Improvements in mechanical modulus or heat deflection temperature are often realized. These fillers may also improve some electrical properties such as corona endurance or dielectric breakdown voltage in polymers...

  12. An explicit reconstruction method for magnetic resonance electrical property tomography based on the generalized Cauchy formula

    Science.gov (United States)

    Nara, Takaaki; Furuichi, Tetsuya; Fushimi, Motofumi

    2017-10-01

    This paper presents an explicit reconstruction formula for magnetic resonance electrical property tomography (MREPT). We derive a Dbar problem from the time-harmonic Maxwell equations under the assumptions that Hz = 0 , \\partial H+ \

  13. Impact of divalent dopant Ca on the electrical properties of ZnO by ...

    Indian Academy of Sciences (India)

    on the electrical properties of ZnO by impedance spectroscopy. TANUSHREE DAS, BIKRAM KESHARI DAS, S K S PARASHAR and KAJAL PARASHAR. ∗. School of Applied Sciences, Nanosensor Lab, KIIT University, Bhubaneswar 751024, India. MS received 1 April 2016; accepted 10 June 2016. Abstract. The electrical ...

  14. The influence of argon ion bombardment on the electrical and optical properties of clean silicon surfaces

    NARCIS (Netherlands)

    Martens, J.W.D.; van den Bogert, W.F.; van Silfhout, Arend

    1981-01-01

    The effect of low energy noble gas ion bombardment on the electrical and optical properties of Si(211) surfaces has been investigated by surface conductivity and field effect measurements, ellipsometry and AES. With this combination of techniques, information is obtained concerning the electrical

  15. Electrical transport and thermoelectric properties of AgPb10SbTe12 ...

    Indian Academy of Sciences (India)

    Thermoelectric material, Ag1−PbSbTe+2 ( = 0.2, = 10), have been successfully prepared by high pressure method. The pressure-dependent electrical transport and thermoelectric properties of Ag0.8Pb10SbTe12 were studied at room temperature. Electrical resistivity and Seebeck coefficient decreases with an ...

  16. Effects of gamma radiolysis on the D.C. electrical properties of ...

    African Journals Online (AJOL)

    Effects of gamma rays on the d.c electrical properties of the aromatic hydrocarbon compound benzene have been studied as a function of temperature in the range from 50 to 500C. The ionic conductivity, pH and the bulk electrical potential of the benzene samples were measured for non-irradiated and irradiated samples at ...

  17. On the optical and electrical properties of rf and ac plasma ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 29; Issue 2. On the optical and electrical ... Abstract. Polyaniline is a widely studied conducting polymer and is a useful material in its bulk and thin film form for many applications, because of its excellent optical and electrical properties. Pristine and iodine doped ...

  18. Rate dependence of electrical and mechanical properties of conductive polymer nanocomposites

    Science.gov (United States)

    Foley, J. R.; Stilson, C. L.; Smith, K. K. G.; McKinion, C. M.; Chen, C.; Ganguli, S.; Roy, A. K.

    2015-09-01

    Conductive polymer nanocomposites with enhanced electrical and thermal properties show promise as an alternative solution for electronic materials. For example, electronic interconnect materials will have comparable electrical and thermal conductivity to solder with an increased operating range of strain and temperature. This paper documents the fabrication and experimental evaluation of a prototype conductive polymer nanocomposite. Material selection, fabrication processes, and initial characterization of a low Tg polymer with a high fill ratio of carbon nanotubes is presented. The electrical and thermal properties of the composite are measured and compared with predictions. The mechanical properties are measured using dynamic mechanical analysis (DMA) over a wide temperature range. The mechanical and electrical responses of the conductive polymer composite are simultaneously measured at higher strain rates using a modified split Hopkinson pressure bar (SHPB) apparatus. The dynamic stress-strain response is obtained using traditional analytic methods (e.g., two- and three-wave analysis). The electrical response is observed using constant current excitation with high bandwidth (>500 kHz) instrumentation. The dynamic compression data implies the change in electrical resistance is solely a function of the material deformation, i.e., the material exhibits constant electrical conductivity and is insensitive to the applied loads. DMA and SHPB dynamic data are used to estimate the parameters in a Mulliken-Boyce constitutive model, and the resulting behavior is critically evaluated. Finally, progress towards improving the polymer composite's mechanical, electrical, and thermal properties are discussed.

  19. B1-based SAR reconstruction using contrast source inversion-electric properties tomography (CSI-EPT)

    NARCIS (Netherlands)

    Balidemaj, Edmond; van den Berg, Cornelis A T; van Lier, A.L.H.M.W.; Nederveen, Aart J; Stalpers, Lukas J A; Crezee, Hans; Remis, Rob F

    Specific absorption rate (SAR) assessment is essential for safety purposes during MR acquisition. Online SAR assessment is not trivial and requires, in addition, knowledge of the electric tissue properties and the electric fields in the human anatomy. In this study, the potential of the recently

  20. B1-based SAR reconstruction using contrast source inversion–electric properties tomography (CSI-EPT)

    NARCIS (Netherlands)

    Balidemaj, E.; van den Berg, CAT; van Lier, ALHMW; Nederveen, AJ; Stalpers, LJA; Crezee, H; Remis, R.F.

    2016-01-01

    Specific absorption rate (SAR) assessment is essential for safety purposes during MR acquisition. Online SAR assessment is not trivial and requires, in addition, knowledge of the electric tissue properties and the electric fields in the human anatomy. In this study, the potential of the recently

  1. Electrical coupling and passive membrane properties of AII amacrine cells.

    Science.gov (United States)

    Veruki, Margaret Lin; Oltedal, Leif; Hartveit, Espen

    2010-03-01

    AII amacrine cells in the mammalian retina are connected via electrical synapses to on-cone bipolar cells and to other AII amacrine cells. To understand synaptic integration in these interneurons, we need information about the junctional conductance (g(j)), the membrane resistance (r(m)), the membrane capacitance (C(m)), and the cytoplasmic resistivity (R(i)). Due to the extensive electrical coupling, it is difficult to obtain estimates of r(m), as well as the relative contribution of the junctional and nonjunctional conductances to the total input resistance of an AII amacrine cell. Here we used dual voltage-clamp recording of pairs of electrically coupled AII amacrine cells in an in vitro slice preparation from rat retina and applied meclofenamic acid (MFA) to block the electrical coupling and isolate single AII amacrines electrically. In the control condition, the input resistance (R(in)) was approximately 620 Mohms and the apparent r(m) was approximately 760 Mohms. After block of electrical coupling, determined by estimating g(j) in the dual recordings, R(in) and r(m) were approximately 4,400 Mohms, suggesting that the nongap junctional conductance of an AII amacrine cell is approximately 16% of the total input conductance. Control experiments with nucleated patches from AII amacrine cells suggested that MFA had no effect on the nongap junctional membrane of these cells. From morphological reconstructions of AII amacrine cells filled with biocytin, we obtained a surface area of approximately 900 microm(2) which, with a standard value for C(m) of 0.01 pF/microm(2), corresponds to an average capacitance of approximately 9 pF and a specific membrane resistance of approximately 41 kohms cm(2). Together with information concerning synaptic connectivity, these data will be important for developing realistic compartmental models of the network of AII amacrine cells.

  2. Electrical properties of spherical dipole antennas with lossy material cores

    DEFF Research Database (Denmark)

    Hansen, Troels Vejle; Kim, Oleksiy S.; Breinbjerg, Olav

    2012-01-01

    and all the provided expressions are exact and valid for arbitrary core sizes, permeability, permittivity, electric and magnetic loss tangents. Arbitrary dispersion models for both permeability and permittivity can be applied. In addition, we present an investigation for an antenna of fixed electrical...... size and permittivity, focusing on the effects of magnetic core losses for a simple magnetic dispersion model, to illustrate how stored energies, efficiency and quality factor are affected. This shows that large magnetic losses can be beneficial, as these can produce a relatively high efficiency....

  3. Electrical properties of improper ferroelectrics from first principles

    OpenAIRE

    Stengel, Massimiliano; Fennie, Craig J.; Ghosez, Philippe

    2012-01-01

    We study the interplay of structural and polar distortions in hexagonal YMnO3 and short-period PbTiO3/SrTiO3 superlattices by means of first-principles calculations at constrained electric displacement field D. We find that in YMnO3 the tilts of the oxygen polyhedra produce a robustly polar ground state, which persists at any choice of the electrical boundary conditions. Conversely, in PTO/STO the antiferrodistortive instabilities alone do not break inversion symmetry, and open-circuit bundar...

  4. Influence of Graphene Oxide on the Tribological and Electrical Properties of PMMA Composites

    Directory of Open Access Journals (Sweden)

    Jiale Song

    2013-01-01

    Full Text Available The graphene oxide (GO was obtained by Hummers' method using natural graphite as raw materials. Then, the GO/poly(methyl methacrylate (PMMA nanocomposites were prepared by in situ polymerization. The tribological and electrical properties of nanocomposites were studied. As a result, the frictional coefficient of GO/PMMA nanocomposites was prominently improved with the content of the graphene oxide increasing. The electrical properties of nanocomposites were slightly increased when adding the graphene oxide.

  5. Mechanical and electrical properties of laminates for high performance printed wiring boards

    Science.gov (United States)

    Guiles, Chester L.

    The physical and electrical properties of laminate boards intended for high-performance applications are reviewed with particular reference to the coefficient of thermal expansion, dielectric constant, and characteristic impedance. It is shown, in particular, that the electrical properties can be tailored to some extent by using various conbinations of basic board materials, such as copper foil, fiberglass fabric, glass fabric, epoxy resin, polyimide resin, aluminum sheet, Kevlar and quartz fabrics, copper-invar-copper, and alumina-ceramic.

  6. Magnetic and electrical properties of epitaxial GeMn

    Energy Technology Data Exchange (ETDEWEB)

    Ahlers, Stefan

    2009-01-15

    In this work, GeMn magnetic semiconductors will be investigated. The fabrication of GeMn thin films with Mn contents up to 11.7% was realised with molecular beam epitaxy. At a fabrication temperature of 60 C, the suppression of Mn{sub x}Ge{sub y} phases could reproducibly be obtained. Dislocation free epitaxy of diamond-lattice type GeMn thin films was observed. In all fabrication conditions where Mn{sub x}Ge{sub y} suppression was feasible, an inhomogeneous dispersion of Mn was observed in form of a self-assembly of nanometre sized, Mn rich regions in a Ge rich matrix. Each Mn rich region exhibits ferromagnetic coupling with high Curie temperatures exceeding, in part, room temperature. The local ferromagnetic ordering leads to the formation of large, spatially separated magnetic moments, which induce a superparamagnetic behaviour of the GeMn thin films. At low temperatures {<=} 20 K, remanent behaviour was found to emerge. X-ray absorption experiments revealed a similarity of the Mn incorporation in diamond-lattice type GeMn thin films and in the hexagonal lattice of the intermetallic Mn{sub 5}Ge{sub 3} phase, respectively. These tetrahedra represent building blocks of the Mn{sub 5}Ge{sub 3} unit cell. The incorporation of Mn{sub 5}Ge{sub 3} building blocks was found to be accompanied by local structural disorder. The electrical properties of GeMn thin films were addressed by transport measurements. It was shown that by using a n-type Ge substrate, a pn energy barrier between epilayers and substrate to suppress parallel substrate conduction paths can be introduced. With the pn barrier concept, first results on the magnetotransport behaviour of GeMn thin films were obtained. GeMn was found to be p-type, but of high resistivity. a series of GeMn thin films was fabricated, where intermetallic Mn{sub x}Ge{sub y} phase separation was supported in a controlled manner. Phase separation was found to result in the formation of partially coherent, nanometre sized Mn{sub 5

  7. Very Compact and Broadband Active Antenna for VHF Band Applications

    Directory of Open Access Journals (Sweden)

    Y. Taachouche

    2012-01-01

    Full Text Available An active receiving antenna with small size consisting of a monopole loaded with a transistor bipolar is presented in this paper. A transistor is used in order to miniaturize the receiving active antenna size in VHF band. The vertical size of the structure is equal to λ/175, where λ is the wavelength at the lower frequency of the bandwidth. Despite the very small size of the antenna, the frequency bandwidth is very wide and the gain is suitable for FM application with sensitive receivers.

  8. Some Electrical Properties of Wild Mango Seed ad Mucuna ...

    African Journals Online (AJOL)

    PROF. O. E. OSUAGWU

    2013-06-01

    Jun 1, 2013 ... The increase and decrease in the values of the electrical resistivity and conductivity were inconsistent with the thickness and diameter of the products. Results showed that temperature and moisture contents had a more significant effect. Key words: receptivity, conductivity, temperature, moisture contents ...

  9. Electrical Properties of Antimony (Sb) Metal Contacts to Silicon (Si ...

    African Journals Online (AJOL)

    The study investigates the behaviour of the contacts formed by Antimony (Sb) metal to Silicon (Si) thin films for electric field values 10 – 100V/m. Measurements of I-v characteristics were obtained at temperatures 303, 313, 323, 333, 343 and 353K respectively. The results show linear I – V relationship over a specified range ...

  10. Effect of ageing treatment on wear properties and electrical ...

    Indian Academy of Sciences (India)

    After the ageing processes, all samples were characterized in terms of electrical conductivity, scanning electron microscope (with energy dispersive X-ray spectrum ... Technical Education Faculty, Department of Machine Education, Karabuk University, Karabük 078100, Turkey; Department of Metal Education, Karabuk ...

  11. Electrical properties of single p-hexaphenylene nanofibers

    DEFF Research Database (Denmark)

    Kjelstrup-Hansen, Jakob; Henrichsen, H.H.; Bøggild, Peter

    2006-01-01

    The electrical characteristics of individual para-hexaphenylene (p6P) nanofibers with typical widths of a few hundred nanometers and heights of a few ten nanometers are investigated. For that purpose we transfer the narofibers onto a lithographically patterned silicon oxide electrode support...

  12. Thermal effects investigation on electrical properties of silicon solar cells treated by laser irradiation

    Directory of Open Access Journals (Sweden)

    Ali Pourakbar Saffar

    2014-12-01

    Full Text Available In this paper, we were investigated electrical properties of monocrystalline and polycrystalline silicon solar cells due to laser irradiation with 650 nm wavelength in two states, proximate irradiation and via optics setup. Thermal effect on the cell surface due to laser irradiation was investigated on electrical properties too. Electrical parameters investigation of solar cells illustrates cell excitement via laser irradiation and efficiency decreases due to cell surface temperature increase. Monocrystalline parameters change with uniform shape due to thermal effect and laser irradiation toward polycrystalline cells.

  13. A Percolation Study of Wettability Effect on the Electrical Properties of Reservoir Rocks

    DEFF Research Database (Denmark)

    Zhou, Dengen; Arbabi, Sepehr; Stenby, Erling Halfdan

    1997-01-01

    Measurements of the electrical resistivity of oil reservoirs are commonly used to estimate other properties of reservoirs, such as porosity and hydrocarbon reserves. However, the interpretation of the measurements is based on empirical correlations, because the underlying mechanisms that control...... the electrical properties of oil bearing rocks have not been well understood. In this paper, we employ percolation concepts to investigate the effect of wettability on the electrical conductivity of a reservoir formation. A three-dimensional simple cubic network is used to represent an ideal reservoir formation...

  14. Electrical and optical properties of p-type InN

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Marie A.; Choi, Soojeong; Bierwagen, Oliver; Smith, Holland M.; Haller, Eugene E.; Speck, James S.; Walukiewicz, Wladek

    2011-01-01

    We have performed comprehensive studies of optical, thermoelectric and electrical properties of Mg doped InN with varying Mg doping levels and sample thicknesses. Room temperature photoluminescence spectra show a Mg acceptor related emission and the thermopower provides clear evidence for the presence of mobile holes. Although the effects of the hole transport are clearly observed in the temperature dependent electrical properties, the sign of the apparent Hall coefficient remains negative in all samples. We show that the standard model of two electrically well connected layers (n-type surface electron accumulation and p-type bulk) does not properly describe Hall effect in p-type InN.

  15. Effect of substrate temperature on structural, morphological, optical and electrical properties of IGZO thin films

    Science.gov (United States)

    Jayaraman, Vinoth Kumar; Álvarez, Arturo Maldonado; Olvera Amador, María de la luz

    2017-02-01

    Indium and gallium co-doped zinc oxide (IGZO) thin films were deposited on glass substrates by ultrasonic spray pyrolysis. Physical properties such as structural, morphological, optical and electrical properties were examined on IGZO thin films with respect to the changes in the substrate temperature (425, 450 and 475 °C). Structural results showed that IGZO films were crystalline and presented hexagonal wurtzite structure. Morphological studies proved that the substrate temperature changed the sizes of hexagonal nanostructures of IGZO. Optical transmittance in the UV-vis region and electrical measurements confirmed that IGZO films were transparent (>70%) with a minimum electrical resistivity 10.5×10-3 Ω cm.

  16. Structural and electrical transport properties of nanosized La0 ...

    Indian Academy of Sciences (India)

    The discovery of manganese-based perovskite materials, called the colossal magne- toresistive (CMR) materials, has generated a considerable interest because of their various electronic, magnetic and structural properties and potential applications. [1–3]. Soon after the discovery and publication of the properties of CMR ...

  17. Electrical, thermoelectric and thermophysical properties of hornet cuticle

    Science.gov (United States)

    Galushko, D.; Ermakov, N.; Karpovski, M.; Palevski, A.; Ishay, J. S.; Bergman, D. J.

    2005-03-01

    Seebeck effect (thermo-emf), thermal conductivity and electrical conductivity of social hornet cuticle were measured in a direction perpendicular to the cuticular surface. The obtained value of the Seebeck coefficient (S) was about 3 ± 0.5 mV K-1 and its sign corresponded to an n-type (electronic) conductivity. Hornet cuticle is shown to be a fairly good heat insulator, with recorded values of the heat conductivity as low as 0.1-0.2 W m-1 K-1. The measured value of the electrical conductivity in the linear regime is σ = 8.5 × 10-5 Ω-1 cm-1. The thermoelectric figure of merit is computed. Implications for possible exploitation as a natural thermoelectric heat pump are discussed.

  18. Petrophysical approach to electrical properties of loose soils

    Directory of Open Access Journals (Sweden)

    В. А. Шевнин

    2017-08-01

    Full Text Available The paper focuses on the relation between geoelectrical characteristics of the soil: resistivity, polarizability and normalized polarizability (ρ, η, Mn – and its superficial conductivity (SC or σ" using methods of vertical electrical sounding with induced polarization (VES-IP, electric profiling with induced polarization (EP-IP and frequency characteristic (FC-IP. The authors demonstrate that superficial conductivity can be determined not only from spectral IP data, but also from soil resistivity obtained through petrophysical measurements. In this case normalized polarizability (Mn is equal to superficial conductivity (SC. Superficial conductivity, in its turn, is proportionate to clay content of the soil. Increasing clayiness reduces hydraulic conductivity. It has been demonstrated that interpretation of EP-IP results benefits from combined study of the plots of three abovementioned parameters (ρ, η, Mn. In the aeration zone, incomplete humidity has a significant effect on geoelectrical parameters of the soil. Petrophysical modelling helps to investigate the impact of humidity.

  19. Statistical Properties of Antenna Impedance in an Electrically Large Cavity

    Energy Technology Data Exchange (ETDEWEB)

    WARNE,LARRY K.; LEE,KELVIN S.H.; HUDSON,H. GERALD; JOHNSON,WILLIAM A.; JORGENSON,ROY E.; STRONACH,STEPHEN L.

    2000-12-13

    This paper presents models and measurements of antenna input impedance in resonant cavities at high frequencies.The behavior of input impedance is useful in determining the transmission and reception characteristics of an antenna (as well as the transmission characteristics of certain apertures). Results are presented for both the case where the cavity is undermoded (modes with separate and discrete spectra) as well as the over moded case (modes with overlapping spectra). A modal series is constructed and analyzed to determine the impedance statistical distribution. Both electrically small as well as electrically longer resonant and wall mounted antennas are analyzed. Measurements in a large mode stirred chamber cavity are compared with calculations. Finally a method based on power arguments is given, yielding simple formulas for the impedance distribution.

  20. Shell-binary nanoparticle materials with variable electrical and electro-mechanical properties.

    Science.gov (United States)

    Zhang, P; Bousack, H; Dai, Y; Offenhäusser, A; Mayer, D

    2018-01-18

    Nanoparticle (NP) materials with the capability to adjust their electrical and electro-mechanical properties facilitate applications in strain sensing technology. Traditional NP materials based on single component NPs lack a systematic and effective means of tuning their electrical and electro-mechanical properties. Here, we report on a new type of shell-binary NP material fabricated by self-assembly with either homogeneous or heterogeneous arrangements of NPs. Variable electrical and electro-mechanical properties were obtained for both materials. We show that the electrical and electro-mechanical properties of these shell-binary NP materials are highly tunable and strongly affected by the NP species as well as their corresponding volume fraction ratio. The conductivity and the gauge factor of these shell-binary NP materials can be altered by about five and two orders of magnitude, respectively. These shell-binary NP materials with different arrangements of NPs also demonstrate different volume fraction dependent electro-mechanical properties. The shell-binary NP materials with a heterogeneous arrangement of NPs exhibit a peaking of the sensitivity at medium mixing ratios, which arises from the aggregation induced local strain enhancement. Studies on the electron transport regimes and micro-morphologies of these shell-binary NP materials revealed the different mechanisms accounting for the variable electrical and electro-mechanical properties. A model based on effective medium theory is used to describe the electrical and electro-mechanical properties of such shell-binary nanomaterials and shows an excellent match with experiment data. These shell-binary NP materials possess great potential applications in high-performance strain sensing technology due to their variable electrical and electro-mechanical properties.

  1. Effect of ageing treatment on wear properties and electrical ...

    Indian Academy of Sciences (India)

    Administrator

    Prior to solid solution heat treatment at 920°C and ageing at 470°C, 500°C and 530°C for 1 h, 2 h and 3 h, respectively, the prepared ... Cu–Cr–Zr; wear; ageing treatment; electrical conductivity. 1. Introduction. Cu–Cr–Zr alloys are used ..... tion coefficient in dry sliding conditions is the formation of oxide layer on the contact ...

  2. Dielectric properties and electrical conductivity of flat micronic graphite/polyurethane composites

    Science.gov (United States)

    Plyushch, Artyom; Macutkevic, Jan; Kuzhir, Polina P.; Banys, Juras; Fierro, Vanessa; Celzard, Alain

    2016-03-01

    Results of broadband dielectric spectroscopy of flat micronic graphite (FMG)/polyurethane (PU) resin composites are presented in a wide temperature range (25-450 K). The electrical percolation threshold was found to lie between 1 and 2 vol. % of FMG. Above the percolation threshold, the composites demonstrated a huge hysteresis of properties on heating and cooling from room temperature up to 450 K, along with extremely high values of dielectric permittivity and electrical conductivity. Annealing proved to be a very simple but powerful tool for significantly improving the electrical properties of FMG-based composites. In order to explain this effect, the distributions of relaxation times were calculated by the complex impedance formalism. Below room temperature, both dielectric permittivity and electrical conductivity exhibited a very low temperature dependence, mainly caused by the different thermal properties of FMG and pure PU matrix.

  3. Neutron intrinsic gettering on electrical property of gate oxynitride in metal-oxide-Si capacitor

    Science.gov (United States)

    Chang-Liao, Kuei-Shu; Yi, Nan-Kuang; Huang, Jenn-Gwo

    2000-05-01

    The electrical property of gate oxynitride in metal-oxide-Si capacitor is improved by a neutron-intrinsic-gettering (NIG) treatment. This improvement can be attributed to the reduction of nitrogen concentration in the oxynitride bulk and the decrease of interstitial oxygen defect in the silicon. For the oxynitride formed using NIG-treated Si substrate, the breakdown electric field is increased and the reliability is improved. A significant improvement of electrical property in gate oxynitride is observed by a NIG treatment including a fast neutron dose of 7.2×1016cm-2 and an anneal at 1100 °C for 6 h. This NIG treatment would be promising for the improvement of electrical properties in gate oxynitrides.

  4. Optical and electrical properties of vanadium pentoxide xerogel films: modification in electric field and the role of ion transport

    Energy Technology Data Exchange (ETDEWEB)

    Pergament, A.L.; Kazakova, E.L.; Stefanovich, G.B. [Petrozavodsk State University, Petrozavodsk (Russian Federation)

    2002-09-07

    Reversible modification of the optical and electrical properties of V{sub 2}O{sub 5}xnH{sub 2}O gel films under the action of an electric field is studied. It is shown that under cathodic polarization (I=10{sup -6}-10{sup -5} A, t{approx}10min, film thickness {approx}10 {mu}m), the films turn from brownish-yellow to red. This internal electrochromic (EC) effect is caused by the redistribution of hydrogen ions inside the film, instead of insertion from the outside (from an electrolyte). A local increase in the hydrogen concentration occurs near the cathode, and this in turn results in modification of the optical properties. The rise of transmittance in the long-wavelength region of the spectrum, as well as the shift of the absorption edge near h{nu}{approx}2.5eV towards longer wavelengths, is observed. In addition, according to the infrared data, some increase in water content also contributes to the process of colouration. The change in the optical properties is accompanied by a change in the electrical properties, namely, an increase in ionic conductivity from {approx}4x10{sup -5} to 10{sup -4}{omega}{sup -1} cm{sup -1}. At higher currents, electroforming resulting from the transport of oxygen ions occurs. This process leads to the formation of a channel consisting of vanadium dioxide due to reduction of V{sub 2}O{sub 5} to VO{sub 2}. Electrical switching with the S-type negative resistance, associated with an electrothermally driven metal-insulator transition in the channel, is observed in the sandwich M/V{sub 2}O{sub 5}xnH{sub 2}O/M devices (unlike the planar devices described in the literature). Finally, applied potentialities of these phenomena for micro- and opto-electronics (EC devices, sensors) are discussed. (author)

  5. Synthesis, growth, optical, mechanical and electrical properties of L ...

    Indian Academy of Sciences (India)

    Ne laser source. Mechanical property of the crystal was determined by Vickers hardness tester. The frequency and temperature dependence of dielectric constant (r), dielectric loss (tan ) and a.c. conductivity (ac) were also measured.

  6. Lightning VHF radiation location system based on short-baseline TDOA technique — Validation in rocket-triggered lightning

    Science.gov (United States)

    Sun, Zhuling; Qie, Xiushu; Liu, Mingyuan; Cao, Dongjie; Wang, Dongfang

    2013-07-01

    A lightning VHF radiation location system based on short-baseline time-difference of arrival (TDOA) technology is newly developed. Based on the orthogonal 10 m-baseline antenna array with four identical broadband flat plane antennas, this system receives the lightning broadband VHF radiation signals and calculates TDOA between antennas in order to determine the location of lightning radiation sources in two dimensions (elevation and azimuth). To reduce noise and improve estimation accuracy of time delay, a general correlation time delay estimation algorithm based on direct correlation method and wavelet transform is proposed. Moreover, parabolic interpolation algorithm is used in the fractional delay estimation to improve the time resolution of the positioning system. In this paper, a rocket-triggered lightning discharge and a cloud lightning discharge are analyzed respectively, combining with simultaneous observations of high-speed camera and fast/slow electric field changes. The results indicate that the TDOA location system could effectively map the lightning radiation sources in 2 dimensions and are in a good agreement with the high-speed video camera images.

  7. Graphene and electric transport properties in graphene-superconductor interfaces

    OpenAIRE

    Manjarrés, Diego; Gómez, Shirley; Herrera, William

    2012-01-01

    El grafeno es una estructura bidimensional de carbono que tiene propiedades electrónicas que no son usuales y  donde los electrones son descritos por la ecuación de Dirac. Este material permite establecer una analogía entre la física de partículas y la materia condensada. La obtención del grafeno hace pocos años ha incentivado una gran cantidad de trabajos experimentales y teóricos con el propósito de poder entender y manipular sus propiedades. Actualmente se han investigado diferentes juntur...

  8. Electric field gradient and electronic properties of crown thioether compounds

    Energy Technology Data Exchange (ETDEWEB)

    Camargo Dalmatti Alves Lima, Filipe, E-mail: flima@if.usp.br; Rodrigues do Nascimento, Rafael; Brown Goncalves, Marcos [Universidade de Sao Paulo, Instituto de Fisica (Brazil); Cottenier, Stefaan [Ghent University, Center for Molecular Modeling (Belgium); Caldas, Marilia Junqueira; Petrilli, Helena Maria [Universidade de Sao Paulo, Instituto de Fisica (Brazil)

    2010-04-15

    We compare published TDPAC experiments on {sup 111}Cd in the crown thioether C{sub 6}H{sub 12}S{sub 3}AgCl with ab-initio electronic structure calculations performed within the framework of the Density Functional Theory using the Projector Augmented Wave method. We conclude from this comparison that the Cd atom at the very moment of the TDPAC experiment is positively charged, and we point out to a methodological difference between reproducing experimental electric-field gradients in molecules versus solid metals.

  9. Laboratory device to analyse the impact of soil properties on electrical and thermal conductivity

    Science.gov (United States)

    Bertermann, David; Schwarz, Hans

    2017-04-01

    Gathering information about soil properties in an efficient way is essential for many soil applications also for very shallow geothermal systems (e.g. collector systems or heat baskets). In the field, electrical resistivity tomogramphy measurements enable non-invasive and extensive analyses regarding the determination of soil properties. For a better understanding of measured electrical resistivity values in relation to soil properties within this study, a laboratory setup was developed. The structure of this laboratory setup is geared to gather electrical resistivity or rather electrical conductivity values which are directly comparable to data measured in the field. Within this setup grain size distribution, moisture content, and bulk density, which are the most important soil parameters affecting the electrical resistivity, can be adjusted. In terms of a better estimation of the geothermal capability of soil, thermal conductivity measurements were also implemented within the laboratory test sequence. The generated data reveals the serious influence of the water content and also provides a huge impact of the bulk density on the electrical as well as on the thermal conductivity. Furthermore, different behaviour patterns of electrical and thermal conductivity in their particular relation to the different soil parameters could be identified.

  10. Electrical properties of smectites; Smectite nendo kobutsu no denkiteki bussei

    Energy Technology Data Exchange (ETDEWEB)

    Takakura, S.; Nishizawa, O.; Aoki, M. [Geological Survey of Japan, Tsukuba (Japan); Kozake, K. [University of Tsukuba, Tsukuba (Japan)

    1997-05-27

    With an objective to evaluate effects of clayish minerals in the electric and electromagnetic exploration methods, resistivities were measured on samples which have adjusted contents of clayish minerals. Samples were prepared for an experiment by mixing 300 g of glass beads having a diameter of about 1 mm, 200 g of aqueous solutions, and 3 to 90 g of smectites. The aqueous solutions used KCL, NaCL and CaCL2 at concentrations of 0.1 to 0.001 mol/L. The result of the experiment may be summarized as follows: among the three kinds of smectites, KN-1 has the greatest effect to reduce the resistivity; the resistivity decreases when the smectite amount is increased except when the concentration of the solution is high; this phenomenon is thought to be caused by increase in the region of an electrically doubled layer which has higher ion concentration; change in the resistivity increases when the solution concentration is low, and decreases when the concentration is high; and in the case of the solution concentration being 0.1 mol/L, the resistivity increases with increase in the smectite content. 5 refs., 7 figs., 1 tab.

  11. Variation in electrical properties of gamma irradiated cadmium selenate nanowires

    Science.gov (United States)

    Chauhan, R. P.; Rana, Pallavi; Narula, Chetna; Panchal, Suresh; Choudhary, Ritika

    2016-07-01

    Preparation of low-dimensional materials attracts more and more interest in the last few years, mainly due to the wide field of potential commercial applications ranging from life sciences, medicine and biotechnology to communication and electronics. One-dimensional systems are the smallest dimension structures that can be used for efficient transport of electrons and thus expected to be critical to the function and integration of nanoscale devices. Nanowires with well controlled morphology and extremely high aspect ratio can be obtained by replicating a nanoporous polymer ion-track membrane with cylindrical pores of controlled dimensions. With this technique, materials can be deposited within the pores of the membrane by electrochemical reduction of the desired ion. In the present study, cadmium selenate nanowires were synthesized potentiostatically via template method. These synthesized nanowires were then exposed to gamma rays by using a 60Co source at the Inter University Accelerator Centre, New Delhi, India. Structural, morphological, electrical and elemental characterizations were made in order to analyze the effect of gamma irradiation on the synthesized nanowires. I-V measurements of cadmium selenate nanowires, before and after irradiation were made with the help of Keithley 2400 source meter and Ecopia probe station. A significant change in the electrical conductivity of cadmium selenate nanowires was found after gamma irradiation. The crystallography of the synthesized nanowires was also studied using a Rigaku X-ray diffractrometer equipped with Cu-Kα radiation. XRD patterns of irradiated samples showed no variation in the peak positions or phase change.

  12. Design, preparation and microwave absorbing properties of resin matrix composites reinforced by SiC fibers with different electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Haitao, E-mail: xzddlht@163.com [Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Science and Technology on Scramjet Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Cheng, Haifeng; Tian, Hao [Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-01-15

    Highlights: • SSMASs have better microwave absorbing properties in smaller thickness. • SSMASs can be realized by SiC fibers with different electrical resistivity. • Resistivity of SiC fibers can be regulated by adjusting surface characteristics. • The bandwidth of SSMASs at reflectivity below −10 dB can reach 11.6 GHz. -- Abstract: One kind of sandwich structure microwave absorbing structures (SSMASs) derived from Salisbury absorbers is reported. The impedance characteristics of SSMASs are analyzed, and the mechanisms of broadening microwave absorbing bandwidth are interpreted by Smith chart. In order to realize SSMASs, high electrical resistivity SiC fibers with Si–C–O surface layers and low electrical resistivity SiC fibers with pyrocarbon surface layers are employed and analyzed by SEM, XPS, AES and HRTEM. The conductive model of SiC fibers with pyrocarbon layers is built and electrical resistivity simulation is done. The SSMASs are fabricated by employing plain woven SiC fiber fabrics with high and low electrical resistivity as reinforcements of dielectric layers and lossy layer, respectively. The microwave absorbing properties of SSMASs are measured and compared with simulated results. The results show that the experimental and simulated results are in good agreement, the SSMASs have better wideband microwave absorbing properties, and the microwave absorbing bandwidth at reflectivity below −10 dB can reach 11.6 GHz.

  13. UCP2- and non-UCP2-mediated electric current in eukaryotic cells exhibits different properties.

    Science.gov (United States)

    Wang, Ruihua; MoYung, K C; Zhang, M H; Poon, Karen

    2015-12-01

    Using live eukaryotic cells, including cancer cells, MCF-7 and HCT-116, normal hepatocytes and red blood cells in anode and potassium ferricyanide in cathode of MFC could generate bio-based electric current. Electrons and protons generated from the metabolic reaction in both cytosol and mitochondria contributing to the leaking would mediate the generation of electric current. Both resveratrol (RVT) and 2,4-dinitrophenol (DNP) used to induce proton leak in mitochondria were found to promote electric current production in all cells except red blood cells without mitochondria. Proton leak might be important for electric current production by bringing the charge balance in cells to enhance the further electron leak. The induced electric current by RVT can be blocked by Genipin, an inhibitor of UCP2-mediated proton leak, while that induced by DNP cannot. RVT could reduce reactive oxygen species (ROS) level in cells better than that of DNP. In addition, RVT increased mitochondrial membrane potential (MMP), while DNP decreased it. Results highly suggested the existence of at least two types of electric current that showed different properties. They included UCP2-mediated and non-UCP2-mediated electric current. UCP2-mediated electric current exhibited higher reactive oxygen species (ROS) reduction effect per unit electric current production than that of non-UCP2-mediated electric current. Higher UCP2-mediated electric current observed in cancer cells might contribute to the mechanism of drug resistence. Correlation could not be established between electric current production with either ROS and MMP without distinguishing the types of electric current.

  14. optical, electrical and solid state properties of nano crystalline zinc ...

    African Journals Online (AJOL)

    Vincent

    reflection coatings on window glass, video screen, camera lenses and other ... potentially important material for antireflection coating for heterojuction ..... REFERENCES. [1] Jyorti, P. B., Barman, J. and Sarma, K. C. (2008). Structural and optical properties of ZnS nanoparticles. Calcogenide Letters, 5 (9), 201-208. [2] Pavan ...

  15. Tailoring of optical and electrical properties of PMMA by ...

    Indian Academy of Sciences (India)

    2017-07-25

    Jul 25, 2017 ... by employing sodium borohydride (NaBH4) as a reducing agent. In this study, PVP-stabilized Ag nanoparticles were prepared and mixed with PMMA solution. Optical ... a unique way of improving their properties [1]. Embedded nanoparticles contribute towards the enhancement in electri- cal, optical and ...

  16. Structural and electrical properties of DC sputtered molybdenum films

    Energy Technology Data Exchange (ETDEWEB)

    Gordillo, G.; Grizalez, M.; Hernandez, L.C. [Laboratorio de Celdas Solares, Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia)

    1998-02-27

    A method is described for the fabrication of low-resistivity molybdenum films on soda-lime glass substrates. Films have been deposited using a DC magnetron sputtering system with a S-gun configuration, and have been characterized through X-ray diffraction, electrical conductivity, and Hall mobility measurements. The influence of the deposition parameters on both the resistivity of the Mo and on the contact resistivity of the Mo/CuInSe{sub 2}/Mo structure has been studied. Values of resistivity ranging from 1.2x10{sup -5} to 36x10{sup -5} {Omega} cm and of contact resistivity ranging from 0.025 to 0.15 {Omega} cm{sup 2} were found

  17. Thermal properties of metals alloy by electrical pyroelectric method (EPE)

    Energy Technology Data Exchange (ETDEWEB)

    Bennaji, N; Mellouki, I; Yacoubi, N, E-mail: bennajin@yahoo.f

    2010-03-01

    In present work, we propose a new technique based on uniform electrical heating of pyroelectric detector which investigated simultaneous thermal conductivity and diffusivity of samples. A new one-dimensional theoretical model was developed to determinate thermal proprieties of steel alloy. The obtained values of thermal conductivity are 13 Wm{sup -1}K{sup -1}, 18 Wm{sup -1}K{sup -1} and 24 Wm{sup -1}K{sup -1} and of thermal diffusivity are 7x10{sup -6} m{sup 2}s{sup -1}, 15x10{sup -6} m{sup 2}s{sup -1} and 8x10{sup -6} m{sup 2}s{sup -1} respectively for sheet steel, galvanized steel and stainless steel. These results are given with an uncertainty at the 1{sigma} level.

  18. Correlation between dielectric property by dielectrophoretic levitation and growth activity of cells exposed to electric field.

    Science.gov (United States)

    Hakoda, Masaru; Hirota, Yusuke

    2013-09-01

    The purpose of this study is to develop a system analyzing cell activity by the dielectrophoresis method. Our previous studies revealed a correlation between the growth activity and dielectric property (Re[K(ω)]) of mouse hybridoma 3-2H3 cells using dielectrophoretic levitation. Furthermore, it was clarified that the differentiation activity of many stem cells could be evaluated by the Re[K(ω)] without differentiation induction. In this paper, 3-2H3 cells exposed to an alternating current (AC) electric field or a direct current (DC) electric field were cultivated, and the influence of damage by the electric field on the growth activity of the cells was examined. To evaluate the activity of the cells by measuring the Re[K(ω)], the correlation between the growth activity and the Re[K(ω)] of the cells exposed to the electric field was examined. The relations between the cell viability, growth activity, and Re[K(ω)] in the cells exposed to the AC electric field were obtained. The growth activity of the cells exposed to the AC electric field could be evaluated by the Re[K(ω)]. Furthermore, it was found that the adverse effects of the electric field on the cell viability and the growth activity were smaller in the AC electric field than the DC electric field.

  19. Diffusive, Structural, Optical, and Electrical Properties of Defects in Semiconductors

    CERN Multimedia

    Wagner, F E

    2002-01-01

    Electronic properties of semiconductors are extremely sensitive to defects and impurities that have localized electronic states with energy levels in the band gap of the semiconductor. Spectroscopic techniques like photoluminescence (PL), deep level transient spectroscopy (DLTS), or Hall effect, that are able to detect and characterize band gap states do not reveal direct information about their microscopic origin. To overcome this chemical "blindness", the present approach is to use radioactive isotopes as a tracer. Moreover, the recoil energies involved in $\\beta$ and $\\gamma$-decays can be used to create intrinsic isolated point defects (interstitials, vacancies) in a controlled way. A microscopic insight into the structure and the thermodynamic properties of complexes formed by interacting defects can be gained by detecting the hyperfine interaction between the nuclear moments of radioactive dopants and the electromagnetic fields present at the site of the radioactive nucleus. The understanding and the co...

  20. Optical and electrical properties of thin superconducting films

    Science.gov (United States)

    Covington, Billy C.; Jing, Feng Chen

    1990-01-01

    Infrared spectroscopic techniques can provide a vital probe of the superconducting energy gap which is one of the most fundamental physical properties of superconductors. Currently, the central questions regarding the optical properties of superconductors are how the energy gap can be measured by infrared techniques and at which frequency the gap exists. An effective infrared spectroscopic method to investigate the superconducting energy gap, Eg, was developed by using the Bomem DA 3.01 Fourier Transformation Spectrophotometer. The reflectivity of a superconducting thin film of YBaCuO deposited on SrTiO3 was measured. A shoulder was observed in the superconducting state reflectance R(sub S) at 480/cm. This gives a value of Eg/kT(sub c) = 7.83, where k is the Boltzmann constant and T(sub c) is the superconducting transition temperature, from which, it is suggested that YBaCuO is a very strong coupling superconductor.

  1. Optical, wetting and electrical properties of functionalized fulleropyrrolidine thin films

    Science.gov (United States)

    Abdulrazack, Parveen; Venkatesan, Sughanya; Chellasamy, Manoharan; Samuthira, Nagarajan

    2017-12-01

    Fulleropyrrolidine derivatives acts as an electron acceptor in the fabrication of solar cells and other optoelectronic devices. In this investigation thin film of functionalized fulleropyrrolidines were fabricated and studied their photo-physical properties. Surface morphology of the thin films was investigated through AFM and FE-SEM. The results suggested that large dependence on structure vs molecular packing. The long alkyl chain substituted C60 were assembled in the form of nanorods. C60- C60 intermolecular distance were measured, the films were with good absorption and exhibits n-type semiconducting behavior. The films were having high contact angle and can be effectively used for fabricating semiconducting devices with self- cleaning property.

  2. Electrical and optical properties of monomeric and polymerized fullerenes. Review

    CERN Document Server

    Makarova, T L

    2001-01-01

    Paper presents the survey of properties of monomeric and polymerized fullerenes as materials with semiconducting zone structures. Electronic structure of fullerenes is studied in detail. One analyzes the absorption spectra of fullerenes. Paper contains data on the transport parameters of fullerenes and discusses, as well, models of conductivity in these materials. Peculiar attention is given to the processes occurring in fullerenes under polymerization through photoexcitation, charge transfer and pressure

  3. Electrical and thermal properties of PLA/CNT composite films

    OpenAIRE

    Ceregatti, Thayara; Pecharki, Paloma; PACHEKOSKI, Wagner M.; Becker,Daniela; Dalmolin, Carla

    2017-01-01

    ABSTRACT Conducting polymers presents many potential applications such as biosensors and biofuelcells. However, to be used in those devices, a thin film must be deposited onto a conducting and biocompatible substrate. In this work, carbon nanotubes (CNT) were mixed in a poly (lactic acid) - PLA - matrix with different compositions (from 0.25 to 5.0 %) in order to form conducting composites suitable to the deposition of a conducting polymer. Thermal properties of PLA/CNT composites were evalua...

  4. Investigation of the stability of electrical properties of reduced LiNbO3 crystals

    Science.gov (United States)

    Yatsenko, A. V.; Pritulenko, A. S.; Yagupov, S. V.; Sugak, D. Yu.; Sol'skii, I. M.

    2017-07-01

    The instability of the electrical properties of lithium niobate single crystals of congruent composition subjected to reducing thermochemical treatment has been investigated by impedance spectroscopy. It has been shown that the subsequent heating of the reduced lithium niobate samples in dry air up to 380 K or higher is accompanied by the progressive increase in their electric resistance, which is due to the oxidization of the crystal surface layers.

  5. Electric field control of magnetic properties and magneto-transport in composite multiferroics.

    Science.gov (United States)

    Udalov, O G; Chtchelkatchev, N M; Beloborodov, I S

    2015-05-13

    We study magnetic state and electron transport properties of composite multiferroic system consisting of a granular ferromagnetic thin film placed above the ferroelectric substrate. Ferroelectricity and magnetism in this case are coupled by the long-range Coulomb interaction. We show that magnetic state and magneto-transport strongly depend on temperature, external electric field and electric polarization of the substrate. Ferromagnetic order exists at finite temperature range around ferroelectric Curie point. Outside the region the film is in the superparamagnetic state. We demonstrate that magnetic phase transition can be driven by an electric field and magneto-resistance effect has two maxima associated with two magnetic phase transitions appearing in the vicinity of the ferroelectric phase transition. We show that positions of these maxima can be shifted by the external electric field and that the magnitude of the magneto-resistance effect depends on the mutual orientation of external electric field and polarization of the substrate.

  6. Electrical and Dielectric Properties of New Natural Cellulosic Fabric Grewia Tilifolia

    Directory of Open Access Journals (Sweden)

    JAYARAMUDU J.

    2010-02-01

    Full Text Available This article deals with the electrical and dielectric properties of new natural cellulosic fabric Grewia tilifolia. Grewia tilifolia is a tree found in India, Sri Lanka, Tropical Africa, Burma and Nepal. The fabric samples of Grewia tilifolia were extracted from the bark of the tree. The electrical (AC conductivity & Impedance and dielectric properties (Dielectric constant & dielectric loss were measured as a function of frequency in the range from 1 kHz to 500 kHz, temperature in the range from 30 °C to 210 °C. Using an LCR Meter (HIOKI 3532-50 LCR Hi Tester, Koizumi, Japan the electrical and dielectric properties were measured. Grewia tilifolia is a subtropical medicinal tree; the stem bark is widely used in traditional Indian medicines to cure pneumonia, bronchitis and urinary infectious disorders.

  7. Modification of optical and electrical properties of chemical bath deposited CdS using plasma treatments

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, G. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); Krishnan, B. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Avellaneda, D.; Castillo, G. Alan; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2011-08-31

    Cadmium sulphide (CdS) is a well known n-type semiconductor that is widely used in solar cells. Here we report preparation and characterization of chemical bath deposited CdS thin films and modification of their optical and electrical properties using plasma treatments. CdS thin films were prepared from a chemical bath containing Cadmium chloride, Triethanolamine and Thiourea under various deposition conditions. Good quality thin films were obtained during deposition times of 5, 10 and 15 min. CdS thin films prepared for 10 min. were treated using a glow discharge plasma having nitrogen and argon carrier gases. The changes in morphology, optical and electrical properties of these plasma treated CdS thin films were analyzed in detail. The results obtained show that plasma treatment is an effective technique in modification of the optical and electrical properties of chemical bath deposited CdS thin films.

  8. Measurement research on magnetic properties of electrical sheet steel under different temperature, harmonic and dc bias

    Directory of Open Access Journals (Sweden)

    Dezhi Chen

    2017-05-01

    Full Text Available The iron core of large power transformer is mainly composed of electrical sheet steel, which is easily affected by temperature, harmonic, and DC bias. Therefore, it is necessary to measure the magnetic properties of electrical sheet steel under different temperature, harmonic and DC Bias. This paper presents the experiment measurement system for the 30ZH120 electrical steel sheet. The B-H magnetization curve, permeability, and loss curve under different temperature, different harmonic, and different DC bias are given, respectively. The simulation of transformer is carried out by using measuring result under DC bias. The presented research provides a reference for optimizing the design of power transformer.

  9. The Effect of Deposition Rate on Electrical, Optical and Structural Properties of ITO Thin Films

    Directory of Open Access Journals (Sweden)

    P. S. Raghupathi

    2005-01-01

    Full Text Available Indium tin oxide (ITO thin films have been prepared using the reactive evaporation technique on glass substrates in an oxygen atmosphere. It is found that the deposition rate plays prominent role in controlling the electrical and optical properties of the ITO thin films. Resistivity, electrical conductivity, activation energy, optical transmission and band gap energy were investigated. A transmittance value of more than 90% in the visible region of the spectrum and an electrical conductivity of 3x10–6 Ωm has been obtained with a deposition rate of 2 nm/min. XRD studies showed that the films are polycrystalline.

  10. Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Deb, K.; Bera, A.; Saha, B., E-mail: biswajit.physics@gmail.com [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Bhowmik, K. L. [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Department of Chemistry, Bir Bikram Memorial College, Agartala, West Tripura 799004 (India); Chattopadhyay, K. K. [Department of Physics, Jadavpur University, Kolkata 700 032 (India)

    2016-05-23

    Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

  11. Electrically conductive gel/fibers composite scaffold with graded properties.

    Science.gov (United States)

    Khorshidi, Sajedeh; Karkhaneh, Akbar

    2017-05-01

    Gradient biomaterials have emerged as fascinating platforms to satisfy the need for imitation of ubiquitous gradients in biology, especially those found at tissue interfaces. In the current study, a gradient fiber-hydrogel scaffold was fabricated to imitate the extracellular matrix of soft-to-hard tissue interfaces. For the fiber proportion, a gradient electrospinning was developed where controlled mixing of solutions with dissimilar concentration of a conductive polymer in injection vessel imparted a composition gradient to electrospinning jet, and thus electrospun fibers. The planar graded fibers were exposed to ultrasound to be three-dimensional and gel permeable. For the hydrogel fraction, a gradient mixing tool was used in which controlled mixing of solutions with disparate concentration of hydrogel components conferred a composition gradient to hydrogel precursor solution. The graded precursor solution was introduced to gradient 3D fibers and then self-crosslinked. Gradient fibers, hydrogel and fiber-gel composite were assessed by many techniques including microscopy, spectroscopy, mechanical analysis and conductivity measurement to ascertain gradient formation. Polymeric constituents' gradient in electrospinning outflow gave rise to not only gradual changes in fiber diameter, also subtle variations in electrical conductivity and other fibers' attributes. Gradient hydrogel making apparatus rendered a steady increase in crosslink involving component and yielded a hydrogel with graded features. The created composite revealed the propitious unification of fibrous and gelation parts into a single scaffold with no detrimental effect on structure and gradient of each part. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Structural, electrical and magnetic properties of transition metal nickel oxides

    Science.gov (United States)

    Wu, Guoqing

    Neutron powder diffraction, high pressure, magnetic susceptibility, and heat capacity measurements, as well as x-ray powder diffraction and iodometric titration, have been conducted on transition metal nickel oxides (TMOs), representative Ruddlesden-Popper (RP) phases Lan+1NinO3n+1 (n = 1, 2, ..., infinity) and hole-doped La2-xSr xNiO4 (0 ≤ x ≤ 1.2). The first complete study of La 2-xSrxNiO4 (0 ≤ x ≤ 1.2) and La n+1NinO3n+1 (n = 2 and 3) phases under high pressure is produced. Strong direct experimental evidence for polaron dominated electrical conduction in these charge transfer (CT) gap La2-xSr xNiO4 compounds is provided. Temperature evolution of the crystal structure of La2-xSrxNiO4 (x = 1/4 and 1/3) is revealed through neutron powder diffraction, structural relationships among n = 1, 2, and 3 phases are exhibited, and charge density wave (CDW) in multilayer Lan+1NinO3n+1 phases is strongly suggested. No superconductivity is observed at pressures up to 1.6 GPa and temperatures down to 4.2 K.

  13. Structural, electrical, electronic and optical properties of melanin films

    Science.gov (United States)

    Abbas, M.; D'Amico, F.; Morresi, L.; Pinto, N.; Ficcadenti, M.; Natali, R.; Ottaviano, L.; Passacantando, M.; Cuccioloni, M.; Angeletti, M.; Gunnella, R.

    2009-03-01

    We present thick, uniform and rather flat melanin films obtained using spray deposition. The morphology of the films was investigated using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Temperature-dependent electrical resistance of melanin thin films evidenced a semiconductor-like character and a hysteretic behavior linked to an irreversible process of water molecule desorption from the melanin film. X-ray Photoelectron Spectroscopy (XPS) was carried out to analyze the role of the functional groups in the primary and secondary structure of the macromolecule, showing that the contribution of the 5,6-dihydroxyindole-2-carboxylic acid (DHICA) subunit to the molecule is about 35%. Comparison of the optical absorption of the thick (800nm) and thin (80nm) films showed a spectral change when the thickness increases. From in vacuum photoconductivity (PC) measured at controlled temperatures, we suggest that the melanin films exhibit a possible charge transport mechanism by means of delocalized π states along the stacked planar secondary structure.

  14. Boron doping of silicon rich carbides: Electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Summonte, C., E-mail: caterina.summonte@cnr.it [Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e i Microsistemi, Bologna (Italy); Canino, M.; Allegrezza, M.; Bellettato, M.; Desalvo, A. [Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e i Microsistemi, Bologna (Italy); Shukla, R. [Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e i Microsistemi, Bologna (Italy); Centre of Non-Conventional Energy Resources, University of Rajasthan, Jaipur (India); Jain, I.P. [Centre of Non-Conventional Energy Resources, University of Rajasthan, Jaipur (India); Crupi, I. [Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e i Microsistemi, Catania (Italy); Milita, S.; Ortolani, L. [Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e i Microsistemi, Bologna (Italy); López-Conesa, L.; Estradé, S.; Peiró, F.; Garrido, B. [MIND – UB, Electronics Department, University of Barcelona, Barcelona (Spain)

    2013-05-15

    Boron doped multilayers based on silicon carbide/silicon rich carbide, aimed at the formation of silicon nanodots for photovoltaic applications, are studied. X-ray diffraction confirms the formation of crystallized Si and 3C-SiC nanodomains. Fourier Transform Infrared spectroscopy indicates the occurrence of remarkable interdiffusion between adjacent layers. However, the investigated material retains memory of the initial dopant distribution. Electrical measurements suggest the presence of an unintentional dopant impurity in the intrinsic SiC matrix. The overall volume concentration of nanodots is determined by optical simulation and is shown not to contribute to lateral conduction. Remarkable higher room temperature dark conductivity is obtained in the multilayer that includes a boron doped well, rather than boron doped barrier, indicating efficient doping in the former case. Room temperature lateral dark conductivity up to 10{sup −3} S/cm is measured on the multilayer with boron doped barrier and well. The result compares favorably with silicon dioxide and makes SiC encouraging for application in photovoltaic devices.

  15. Miniaturization for ultrathin metamaterial perfect absorber in the VHF band

    Science.gov (United States)

    Khuyen, Bui Xuan; Tung, Bui Son; Yoo, Young Joon; Kim, Young Ju; Kim, Ki Won; Chen, Liang-Yao; Lam, Vu Dinh; Lee, Youngpak

    2017-03-01

    An efficient resolution for ultrathin metamaterial perfect absorber (MPA) is proposed and demonstrated in the VHF radio band (30-300 MHz). By adjusting the lumped capacitors and the through vertical interconnects, the absorber is miniaturized to be only λ/816 and λ/84 for its thickness and periodicity with respect to the operating wavelength (at 102 MHz), respectively. The detailed simulation and calculation show that the MPA can maintain an absorption rate over 90% in a certain range of incident angle and with a wide variation of capacitance. Additionally, we utilized the advantages of the initial single-band structure to realize a nearly perfect dual-band absorber in the same range. The results were confirmed by both simulation and experiment at oblique incidence angles up to 50°. Our work is expected to contribute to the actualization of future metamaterial-based devices working at radio frequency.

  16. Electrical Properties of Multi-Pyrene/Porphyrin-Dendrimers

    Directory of Open Access Journals (Sweden)

    Mark Euguenii Martínez-Klimov

    2015-09-01

    Full Text Available Dendrimers bearing pyrene donor groups have been obtained and act as efficient light-harvesting antennae capable of transferring light energy through space from their periphery to their core. The light-harvesting ability increases with each generation due to an increase in the number of peripheral pyrenes. In order to evaluate the photovoltaic properties of the compounds, thermal evaporated thin films were produced and the voltage response in the presence of visible light was obtained. The energy transfer efficiency was found to be almost quantitative for the first and second generations. The dendrimers have the potential to become integral components of molecular photonic devices.

  17. Electron beam induced modifications in flexible biaxially oriented polyethylene terephthalate sheets: Improved mechanical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhary, N. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Koiry, S.P. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Singh, A., E-mail: asb_barc@yahoo.com [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Tillu, A.R. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Jha, P.; Samanta, S.; Debnath, A.K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Aswal, D.K., E-mail: dkaswal@yahoo.com [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Mondal, R.K. [Radiation Technology Development Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India); Acharya, S.; Mittal, K.C. [Accelerator & Pulse Power Division, Bhabha Atomic Research Centre, Mumbai, 400 085 (India)

    2017-03-01

    In the present work, we have studied the effects of electron beam irradiation (with dose ranging from 2 to 32 kGy) on mechanical and electrical properties of biaxially oriented polyethylene terephthalate (BOPET) sheets. The sol-gel analysis, Fourier transformation infra-red (FTIR), X-ray photoelectron spectroscopy (XPS) characterizations of the irradiated BOPET sheets suggest partial cross-linking of PET chains through the diethylene glycol (DEG). The mechanical properties of BOPET, such as, tensile strength, Young's modulus and electrical resistivity shows improvement with increasing dose and saturate for doses >10 kGy. The improved mechanical properties and high electrical resistivity of electron beam modified BOPET sheets may have additional advantages in applications, such as, packaging materials for food irradiation, medical product sterilization and electronic industries. - Graphical abstract: Irradiation of BOPET by electron beam leads to the formation of diethylene glycol that crosslink's the PET chains, resulting in improved mechanical properties and enhanced electrical resistivity. - Highlights: • BOPET exhibit improved tensile strength/Young's modulus after e-beam exposure. • Electrical resistivity of BOPET increases after e-beam exposure. • Cross-linking of PET chains through diethylene glycol was observed after e-beam exposure.

  18. Chemical Partitioning and Resultant Effects on Structure and Electrical Properties in Co-Containing Magnetic Amorphous Nanocomposites for Electric Motors

    Science.gov (United States)

    DeGeorge, Vincent G.

    The chemical partitioning of Cobalt-containing soft magnetic amorphous and nanocomposite materials has been studied with particular focus on its consequences on these materials' nanostructure and electrical resistivity. Theory, models, and discussion in this regard are presented on this class of materials generally, and are detailed in particular on alloys of composition, (Fe65Co35)79.5+xB13Si2Nb4-xCu1.5, for X={0-4at%}, and Co-based, Co76+YFe4Mn4-YB14Si2Nb4, for Y={0-4at%}. The context of this work is within the ongoing efforts to integrate soft magnetic metal amorphous and nanocomposite materials into electric motor applications by leveraging material properties with motor topology in order to increase the electrical efficiency and decrease the size, the usage of rare-earth permanent magnets, and the power losses of electric motors. A mass balance model derived from consideration of the partitioning of glass forming elements relates local composition to crystal state in these alloys. The 'polymorphic burst' onset mechanism and a Time-Temperature-Transformation diagram for secondary crystallization are also presented in relation to the partitioning of glass forming elements. Further, the intrinsic electrical resistivity of the material is related to the formation of virtual bound states due to dilute amounts of the glass forming elements. And lastly, a multiphase resistivity model for the effective composite resistivity that accounts for the amorphous, crystalline, and glass former-rich amorphous regions, each with distinct intrinsic resistivity, is also presented. The presented models are validated experimentally on the Co-containing alloys by Atom Probe Tomography performed through collaboration with Pacific Northwestern National Laboratory.

  19. Extraction of forest stand parameters from CARABAS VHF SAR images

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Fredrik [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Centre for Image Analysis

    1999-10-01

    Methods for extracting stand-wise forest parameters from CARABAS VHF SAR images have been developed and evaluated. CARABAS is a unique airborne synthetic aperture radar (SAR), developed by the Swedish Defence Research Establishment. It differs a lot from ordinary microwave radars by using wavelengths between 3.3 and 15 m, making the image intensity highly correlated to stem volume. Furthermore, by providing its own illumination source, the sensor operates independently of daylight and weather conditions. Empirical regression models have been developed for relating backscattering amplitude to stem volume, stem diameter, and tree height. To make comparison between CARABAS image data and forest parameters effective, a fully automatic geo-coding algorithm was developed. Image texture features have also been investigated. By using the variogram as a discriminating feature, CARABAS images and aerial images were segmented into homogeneous regions. Furthermore, a method for discriminating recently clear felled areas from forested areas, combining information from Almaz-1 SAR images and SPOT panchromatic data has also been developed, serving as a comparison to the main work of this thesis. For forest stands at near-horizontal ground, the results for estimating stem volume, stem diameter, and tree height from CARABAS image data are very satisfactory. The root mean square errors for the estimates are comparable to subjective ground-based inventories for dense forest stands. The methods and algorithms described in this thesis have been developed towards an operational remote sensing tool. Altogether, significant potential for mapping of forest characteristics exists using the CARABAS VHF SAR sensor 57 refs, 14 figs, 7 tabs

  20. Microfluidic Impedance Flow Cytometry Enabling High-Throughput Single-Cell Electrical Property Characterization

    Directory of Open Access Journals (Sweden)

    Jian Chen

    2015-04-01

    Full Text Available This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1 early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2 microfluidic impedance flow cytometry with enhanced sensitivity; (3 microfluidic impedance and optical flow cytometry for single-cell analysis and (4 integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications.

  1. Microfluidic impedance flow cytometry enabling high-throughput single-cell electrical property characterization.

    Science.gov (United States)

    Chen, Jian; Xue, Chengcheng; Zhao, Yang; Chen, Deyong; Wu, Min-Hsien; Wang, Junbo

    2015-04-29

    This article reviews recent developments in microfluidic impedance flow cytometry for high-throughput electrical property characterization of single cells. Four major perspectives of microfluidic impedance flow cytometry for single-cell characterization are included in this review: (1) early developments of microfluidic impedance flow cytometry for single-cell electrical property characterization; (2) microfluidic impedance flow cytometry with enhanced sensitivity; (3) microfluidic impedance and optical flow cytometry for single-cell analysis and (4) integrated point of care system based on microfluidic impedance flow cytometry. We examine the advantages and limitations of each technique and discuss future research opportunities from the perspectives of both technical innovation and clinical applications.

  2. The effect of electron induced hydrogenation of graphene on its electrical transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Sung Oh [Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); Teizer, Winfried [Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); WPI-Advanced Institute for Materials Research, Tohoku University, Sendai (Japan)

    2013-07-22

    We report a deterioration of the electrical transport properties of a graphene field effect transistor due to energetic electron irradiation on a stack of Poly Methyl Methacrylate (PMMA) on graphene (PMMA/graphene bilayer). Prior to electron irradiation, we observed that the PMMA layer on graphene does not deteriorate the carrier transport of graphene but improves its electrical properties instead. As a result of the electron irradiation on the PMMA/graphene bilayer, the Raman “D” band appears after removal of PMMA. We argue that the degradation of the transport behavior originates from the binding of hydrogen generated during the PMMA backbone secession process.

  3. Structural and electrical properties of functionalized multiwalled carbon nanotube/epoxy composite

    Energy Technology Data Exchange (ETDEWEB)

    Gantayat, S., E-mail: subhra-gantayat@rediffmail.com; Rout, D. [School of Applied Sciences, KIIT University, Bhubaneswar-751024, Odisha (India); Swain, S. K. [Department of Chemistry, Veer Surendra Sai University of Technology, Burla, Sambalpur-768018, Odisha (India)

    2016-05-23

    The effect of the functionalization of multiwalled carbon nanotube on the structure and electrical properties of composites was investigated. Samples based on epoxy resin with different weight percentage of MWCNTs were prepared and characterized. The interaction between MWCNT & epoxy resin was noticed by Fourier transform infrared spectroscopy (FTIR). The structure of functionalized multiwalled carbon nanotube (f-MWCNT) reinforced epoxy composite was studied by field emission scanning electron microscope (FESEM). The dispersion of f-MWCNT in epoxy resin was evidenced by high resolution transmission electron microscope (HRTEM). Electrical properties of epoxy/f-MWCNT nanocomposites were measured & the result indicated that the conductivity increased with increasing concentration of f-MWCNTs.

  4. Mapping the electrical properties of semiconductor junctions - the electron holographic approach

    DEFF Research Database (Denmark)

    Twitchett-Harrison, A.C.; Dunin-Borkowski, Rafal E.; Midgley, P.A.

    2008-01-01

    The need to determine the electrical properties of semiconductor junctions with high spatial resolution Is as pressing now as ever. One technique that offers the possibility of quantitative high-resolution mapping of two- and three-dimensional electrostatic potential distributions is off-axis ele......The need to determine the electrical properties of semiconductor junctions with high spatial resolution Is as pressing now as ever. One technique that offers the possibility of quantitative high-resolution mapping of two- and three-dimensional electrostatic potential distributions is off...

  5. Electrical Properties of Barium and Zirconium Modified NBT Ferroelectric Ceramics

    Science.gov (United States)

    Rao, K. Sambasiva; Tilak, B.; Rajulu, K. Ch. Varada; Swathi, A.; Workineh, Haileeyesus

    2011-11-01

    Recently a new wave of interest has risen on relaxor ferroelectrics with complex perovskite structure due to their wide use in fabrication of multilayer ceramic capacitors, electrostrictive actuators, and electromechanical transducers. The polycrystalline 0.93(Bi0.5Na0.5)Ba0.07Z0.04T0.96O3 (0.07BNBZT) ceramic material, which is in the vicinity of the morphotropic phase boundary (MPB) has been prepared by using high temperature solid state reaction method. The tolerance factor has been estimated and found to be 0.815. XRD analysis revealed a rhombohedral perovskite type structure. SEM micrographs showed highly dense grains with rectangular shape. The average grain size is found to be 1.51μm. Dielectric studies in the material ha indicated relaxor behaviour with diffuse phase transition. High value of ɛm>1958 is found at 1kHz, Tm (phase transition temperature) 335 °C, The diffuseness parameter was established to be 1.60 revealing the relaxor behaviour. Further, to confirm the relaxor behaviour in the material, Vogel-Fulcher (V-F) relation has been used. Estimated V-F parameters are found to be Tf = 138 °C, Ea = 0.080 eV and νo = 2.32×108 Hz. Cole-Cole analysis has shown a non-Debye type relaxation in the system. Conductivity studies in the material obeyed the Jonscher's power law in frequency range of (45Hz-5MHz) and temperature range of (35 °C-600 °C). The electric conduction in the system may be due to hopping/mobility/ transportation of charge carriers.

  6. Electrical properties of foamed polypropylene/carbon black composites

    Science.gov (United States)

    Iliev, M.; Kotzev, G.; Vulchev, V.

    2016-02-01

    Polypropylene composites containing carbon black fillers were produced by vibration assisted extrusion process. Solid (unfoamed) composite samples were molded by conventional injection molding method, while structural foams were molded by a low pressure process. The foamed samples were evidenced to have a solid skin-foamed core structure which main parameters were found to depend on the quantity of material injected in the mold. The average bubbles' sizes and their distribution were investigated by scanning electron microscopy. It is established that the conductivity of the foamed samples gradually decreases when reducing the sample density. Nevertheless, the conductivity is found to be lower than the conductivity of the unfoamed samples both being of the same order. The flexural properties of the composites were studied and the results were discussed in the context of the structure parameters of the foamed samples.

  7. Physicochemical Properties of Biopolymer Hydrogels Treated by Direct Electric Current

    Directory of Open Access Journals (Sweden)

    Żaneta Król

    2016-07-01

    Full Text Available The objective of this study was to evaluate the changes within the physicochemical properties of gelatine (2%; 4%; 8%, carrageenan (1.5%; 2%; 2.5% and sodium alginate (0.75%; 1%; 1.25% hydrogels with different sodium chloride concentrations that were triggered by applying direct current (DC of 400 mA for a duration of five minutes. There were three types of gels prepared for the purpose of the study: C, control; H, gels on the basis of hydrosols that were treated with DC; and G, gels treated with DC. In the course of the study, the authors carried out the following analyses: Texture Profile Analysis (TPA, Fourier Transform Infrared spectroscopy (FTIR, Scanning Electron Microscopy (SEM and Swelling Ratio (SR. Furthermore, the color and pH of hydrogels were measured. The FTIR spectra showed that the structures of gelatine, carrageenan and sodium alginate do not significantly change upon applying DC. The results of TPA, SR, color and pH measurement indicate that hydrogels’ properties are significantly dependent on the type of polymer, its concentration and the type of the gel. By changing those parameters, the characteristics of such gels can be additionally tuned, which extends their applicability, e.g., in the food industry. Moreover, the analysis revealed that SR of H gel gelatine after 72 h of storage was 1.84-times higher than SR of the control sample, which indicated that this gel may be considered as a possible component for wound dressing materials.

  8. Metal-Polymer Nanocomposites: (Co-Evaporation/(CoSputtering Approaches and Electrical Properties

    Directory of Open Access Journals (Sweden)

    Vanna Torrisi

    2015-07-01

    Full Text Available In this review, we discuss the basic concepts related to (co-evaporation and (cosputtering based fabrication methods and the electrical properties of polymer-metal nanocomposite films. Within the organic-inorganic hybrid nanocomposites research framework, the field related to metal-polymer nanocomposites is attracting much interest. In fact, it is opening pathways for engineering flexible composites that exhibit advantageous electrical, optical, or mechanical properties. The metal-polymer nanocomposites research field is, now, a wide, complex, and important part of the nanotechnology revolution. So, with this review we aim, starting from the discussion of specific cases, to focus our attention on the basic microscopic mechanisms and processes and the general concepts suitable for the interpretation of material properties and structure–property correlations. The review aims, in addition, to provide a comprehensive schematization of the main technological applications currently in development worldwide.

  9. Influence of cadmium sulfide nanoparticles on structural and electrical properties of polyvinyl alcohol films

    Directory of Open Access Journals (Sweden)

    J. Koteswararao

    2016-11-01

    Full Text Available Cadmium sulfide (CdS nanoparticles have been synthesized by hydrothermal method and dispersed in poly vinyl alcohol (PVA matrix in varying amounts by weight. Subsequently, PVA/CdS nanocomposites have been synthesized with the objective of investigating the effect of CdS nanoparticles on structural and electrical properties of PVA films. Structural properties were analyzed by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD and scanning electron microscopy (SEM techniques. Differential scanning calorimetry (DSC was used to investigate thermal properties of PVA/CdS nanocomposites. Electrical properties were measured by using high frequency LCR meter and were found to be strongly dependent on frequency and nano CdS content. Dielectric constant decreased with increase in frequency and with increase in nanofiller concentration. AC conductivity and dielectric loss increased with frequency and decreased with increase in nano CdS content.

  10. Electric and magnetic properties of contrast agents for thermoacoustic imaging

    Science.gov (United States)

    Ogunlade, Olumide; Beard, Paul

    2014-03-01

    The endogenous contrast in thermoacoustic imaging is due to the water and ionic content in tissue. This results in poor tissue speci city between high water content tissues. As a result, exogenous contrast agents have been employed to improve tissue speci city and also increase the SNR. An investigation into the sources of contrast produced by several exogenous contrast agents is described. These include three gadolinium based MRI contrast agents, iron oxide particles, single wall carbon nanotubes, saline and sucrose solutions. Both the dielectric and magnetic properties of contrast agents at 3GHz have been measured using microwave resonant cavities. The DC conductivity of the contrast agents were also measured. It is shown that the measured increase in dielectric contrast, relative to water, is due to dipole rotational loss of polar non electrolytes, ionic loss of electrolytes or a combination of both. It is shown that for the same dielectric contrast, electrolytes make better thermoacoustic contrast agents than non-electrolytes, for thermoacoustic imaging.

  11. Manipulating the Interfacial Electrical and Optical Properties of Dissimilar Materials with Metallic Nanostructures

    Science.gov (United States)

    2016-07-30

    AFRL-AFOSR-VA-TR-2016-0281 MANIPULATING THE INTERFACIAL ELECTRIAL & OPTICAL PROPERTIES OF DISSIMILA Seth Bank UNIVERSITY OF TEXAS AT AUSTIN 101 EAST...From - To) 1 May 2010 - 30 Apr 2016 4. TITLE AND SUBTITLE Manipulating the Interfacial Electrical & Optical Properties of Dissimilar Materials with...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) The University of Texas at Austin 101 E. 27th, Ste

  12. Influence of the mechanical fatigue progress on the magnetic properties of electrical steel sheets

    Directory of Open Access Journals (Sweden)

    Karthaus Jan

    2017-06-01

    Full Text Available The purpose of this paper is to study the variation of the magnetic properties of non-oriented electrical steel sheets with the fatigue state during cyclic mechanical loading. The obtained results are central to the design of variable drives such as traction drives in electric vehicles in which varying mechanical loads, e.g. in the rotor core (centrifugal forces, alter the magnetic properties. Specimens of non-oriented electrical steel are subject to a cyclically varying mechanical tensile stress with different stress amplitudes and number of cycles. The specimens are characterised magnetically at different fatigue states for different magnetic flux densities and magnetising frequencies. The measurements show a variation in magnetic properties depending on the number of cycles and stress magnitude which can be explained by changes in the material structure due to a beginning mechanical fatigue process. The studied effect is critical for the estimation of the impact of mechanical material fatigue on the operational behaviour of electrical machines. Particularly in electrical machines with a higher speed where the rotor is stressed by high centrifugal forces, material fatigue occurs and can lead to deterioration of the rotor’s stack lamination.

  13. Quantitative conductivity and permittivity imaging of the human brain using electric properties tomography.

    Science.gov (United States)

    Voigt, Tobias; Katscher, Ulrich; Doessel, Olaf

    2011-08-01

    The electric properties of human tissue can potentially be used as an additional diagnostic parameter, e.g., in tumor diagnosis. In the framework of radiofrequency safety, the electric conductivity of tissue is needed to correctly estimate the local specific absorption rate distribution during MR measurements. In this study, a recently developed approach, called electric properties tomography (EPT) is adapted for and applied to in vivo imaging. It derives the patient's electric conductivity and permittivity from the spatial sensitivity distributions of the applied radiofrequency coils. In contrast to other methods to measure the patient's electric properties, EPT does not apply externally mounted electrodes, currents, or radiofrequency probes, which enhances the practicability of the approach. This work shows that conductivity distributions can be reconstructed from phase images and permittivity distributions can be reconstructed from magnitude images of the radiofrequency transmit field. Corresponding numerical simulations using finite-difference time-domain methods support the feasibility of this phase-based conductivity imaging and magnitude-based permittivity imaging. Using this approximation, three-dimensional in vivo conductivity and permittivity maps of the human brain are obtained in 5 and 13 min, respectively, which can be considered a step toward clinical feasibility for EPT. Copyright © 2011 Wiley-Liss, Inc.

  14. Effects of silver impurity on the structural, electrical, and optical properties of ZnO nanowires

    Directory of Open Access Journals (Sweden)

    Kim Sangsig

    2011-01-01

    Full Text Available Abstract 1, 3, and 5 wt.% silver-doped ZnO (SZO nanowires (NWs are grown by hot-walled pulsed laser deposition. After silver-doping process, SZO NWs show some change behaviors, including structural, electrical, and optical properties. In case of structural property, the primary growth plane of SZO NWs is switched from (002 to (103 plane, and the electrical properties of SZO NWs are variously measured to be about 4.26 × 106, 1.34 × 106, and 3.04 × 105 Ω for 1, 3, and 5 SZO NWs, respectively. In other words, the electrical properties of SZO NWs depend on different Ag ratios resulting in controlling the carrier concentration. Finally, the optical properties of SZO NWs are investigated to confirm p-type semiconductor by observing the exciton bound to a neutral acceptor (A0X. Also, Ag presence in ZnO NWs is directly detected by both X-ray photoelectron spectroscopy and energy dispersive spectroscopy. These results imply that Ag doping facilitates the possibility of changing the properties in ZnO NWs by the atomic substitution of Ag with Zn in the lattice.

  15. Effect of elastic and plastic tensile mechanical loading on the magnetic properties of NGO electrical steel

    Science.gov (United States)

    Leuning, N.; Steentjes, S.; Schulte, M.; Bleck, W.; Hameyer, K.

    2016-11-01

    The magnetic properties of non-grain-oriented (NGO) electrical steels are highly susceptible to mechanical stresses, i.e., residual, external or thermal ones. For rotating electrical machines, mechanical stresses are inevitable and originate from different sources, e.g., material processing, machine manufacturing and operating conditions. The efficiency and specific losses are largely altered by different mechanical stress states. In this paper the effect of tensile stresses and plastic deformations on the magnetic properties of a 2.9 wt% Si electrical steel are studied. Particular attention is paid to the effect of magnetic anisotropy, i.e., the influence of the direction of applied mechanical stress with respect to the rolling direction. Due to mechanical stress, the induced anisotropy has to be evaluated as it is related to the stress-dependent magnetostriction constant and the grain alignment.

  16. Influence of dopant concentration on the electrical properties of the CdSe-PMMA nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Ramneek; Tripathi, S. K., E-mail: surya@pu.ac.in, E-mail: surya-tr@yahoo.com [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India)

    2016-05-06

    This paper reports the synthesis and electrical characterization of CdSe-PMMA nanocomposite. CdSe-PMMA nanocomposite has been prepared by ex-situ technique through chemical route. The influence of three different Ag doping concentrations on the electrical properties has been studied in the temperature range ∼ 303-353 K. Transmission electron micrograph reveals the spherical morphology of the CdSe nanoparticles and their proper dispersion in the PMMA matrix. The electrical conduction of the polymer nanocomposites is through thermally activated process with single activation energy. With Ag doping, initially the activation energy increases upto 0.2 % Ag doping concentration but with further increase in Ag concentration, it decreases. This behavior has been discussed on the basis of randomly oriented grain boundaries and defect states. Thus, the results indicate that the transport properties of the polymer nanocomposites can be tailored by controlled doping concentration.

  17. Influence of dopant concentration on the electrical properties of the CdSe-PMMA nanocomposite

    Science.gov (United States)

    Kaur, Ramneek; Tripathi, S. K.

    2016-05-01

    This paper reports the synthesis and electrical characterization of CdSe-PMMA nanocomposite. CdSe-PMMA nanocomposite has been prepared by ex-situ technique through chemical route. The influence of three different Ag doping concentrations on the electrical properties has been studied in the temperature range ˜ 303-353 K. Transmission electron micrograph reveals the spherical morphology of the CdSe nanoparticles and their proper dispersion in the PMMA matrix. The electrical conduction of the polymer nanocomposites is through thermally activated process with single activation energy. With Ag doping, initially the activation energy increases upto 0.2 % Ag doping concentration but with further increase in Ag concentration, it decreases. This behavior has been discussed on the basis of randomly oriented grain boundaries and defect states. Thus, the results indicate that the transport properties of the polymer nanocomposites can be tailored by controlled doping concentration.

  18. Crystal structure and electrical transport properties of single layered perovskite LaSrCoO4

    Science.gov (United States)

    Ahad, Abdul; Shukla, D. K.; Rahman, F.; Majid, S.; Tarachand; Okram, G. S.; Phase, D. M.

    2016-10-01

    We present here investigations on the influence of structure on electrical transport properties of polycrystalline LaSrCoO4 that is single layered perovskite with K2NiF4 type structure synthesized using solid state reaction route. Using Reitveld refinement of X-ray diffraction (XRD) data, it is found that the sample is in single phase with tetragonal structure (space group I4/mmm). Electrical resistivity performed in the temperature range 140-300K shows semiconducting character of the sample. Considerable contrasts in the Co-O bond length is associated with the intermediate spin (IS) state of Co ion that correlates the structural and transport properties. Detailed analysis indicates that the temperature dependent electrical resistivity follows the three-dimensional variable range hopping (VRH) model in low temperature region below 225K. The high temperature (225-300K) resistivity data has been found to follow the thermally activated behaviour.

  19. IONIC CONDUCTIVITY AND ELECTRICAL PROPERTIES OF CARBOXYMETHYL CELLULOSE - NH4Cl SOLID POLYMER ELECTROLYTES

    Directory of Open Access Journals (Sweden)

    N. H. AHMAD

    2016-06-01

    Full Text Available In this present work, carboxymethyl cellulose (CMC – ammonium chloride (NH4Cl solid polymer electrolyte (SPE films were prepared by solution casting method. The ionic conductivity and electrical properties of SPE films were investigated using Electrical Impedance Spectroscopy. SPE film containing 16 wt. % NH4Cl exhibited the highest ionic conductivity of 1.43 x 10-3 S/cm at ambient temperature, 303K. The temperature dependence SPE films showed an Arrhenius-type relation where the regression values obtained from the log conductivity versus reciprocal temperature is close to unity (R2≈1. The electrical properties have been measured as a function of frequency of Ԑr,Ԑi, Mr, Mi shown a non-Debye type behavior

  20. Optical and electrical properties of electrochemically deposited polyaniline/CeO{sub 2} hybrid nanocomposite film

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Anees A.; Khan, M. A. M.; Khan, M. Naziruddin; Alrokayan, Salman A.; Alhoshan, M.; Alsalhi, M. S., E-mail: aneesaansari@gmail.com [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh-11451, P. O. Box-2454 (Saudi Arabia)

    2011-04-15

    This paper reports the optical and electrical properties of electrochemically deposited polyaniline (PANI)/cerium oxide (CeO{sub 2}) hybrid nano-composite film onto indium-tin-oxide (ITO) glass substrate. UV-visible spectroscopy and I-V characteristic were performed to study the optical and electrical parameters of the electrochemically deposited film. The film exhibited a strong absorption below 400 nm (3.10 eV) with a well defined absorbance peak at around 285 nm (4.35 eV). The estimated band gap of the CeO{sub 2} sample was 3.44 eV, higher than bulk CeO{sub 2} powder (E{sub g} = 3.19 eV) due to the quantum confinement effect. Optical and electrochemical characteristics indicated that the electrical properties of PANI/CeO{sub 2} hybrid nanocomposite film are dominated by PANI doping. (semiconductor materials)

  1. Optical and electrical properties of electrochemically deposited polyaniline/CeO2 hybrid nanocomposite film

    Science.gov (United States)

    Ansari, Anees A.; Khan, M. A. M.; Naziruddin Khan, M.; Alrokayan, Salman A.; Alhoshan, M.; Alsalhi, M. S.

    2011-04-01

    This paper reports the optical and electrical properties of electrochemically deposited polyaniline (PANI)/cerium oxide (CeO2) hybrid nano-composite film onto indium-tin-oxide (ITO) glass substrate. UV-visible spectroscopy and I—V characteristic were performed to study the optical and electrical parameters of the electrochemically deposited film. The film exhibited a strong absorption below 400 nm (3.10 eV) with a well defined absorbance peak at around 285 nm (4.35 eV). The estimated band gap of the CeO2 sample was 3.44 eV, higher than bulk CeO2 powder (Eg = 3.19 eV) due to the quantum confinement effect. Optical and electrochemical characteristics indicated that the electrical properties of PANI/CeO2 hybrid nanocomposite film are dominated by PANI doping.

  2. The influence of metal nanoparticles on electrical properties of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Janas, Dawid, E-mail: dawid.janas@gmail.com; Koziol, Krzysztof K.K., E-mail: kk292@cam.ac.uk

    2016-07-15

    Highlights: • Metal nanoparticles were deposited onto carbon nanotube films. • Metal-CNT nanocomposites showed very interesting electrical, thermal and surface properties. • Tailoring of the size of metal nanoclusters shows big potential for catalysis. - Abstract: First, sputtering deposition of Au, Ag, Pt and Pd resulted in changes to the electrical resistance of carbon nanotube (CNT) films due to electron localization followed by creation of percolation pathways. Metal-CNT composites created this way showed different reaction of electrical resistance to temperature as well as thermal stability. Furthermore, their surface properties show much higher affinity towards aqueous media than as-made CNT films. Finally, we have developed an easy way of tailoring the size of metal clusters on the surface of CNT films depending on the employed deposition and heating conditions. Electrothermal sintering yielded metal clusters of controlled size that showed big potential for the application in catalyst-assisted chemical transformations.

  3. Flexible graphene-graphene composites of superior thermal and electrical transport properties.

    Science.gov (United States)

    Hou, Zhi-Ling; Song, Wei-Li; Wang, Ping; Meziani, Mohammed J; Kong, Chang Yi; Anderson, Ankoma; Maimaiti, Halidan; LeCroy, Gregory E; Qian, Haijun; Sun, Ya-Ping

    2014-09-10

    Graphene is known for high thermal and electrical conductivities. In the preparation of neat carbon materials based on graphene, a common approach has been the use of well-exfoliated graphene oxides (GOs) as the precursor, followed by conversion to reduced GOs (rGOs). However, rGOs are more suitable for the targeted high electrical conductivity achievable through percolation but considerably less effective in terms of efficient thermal transport dictated by phonon progression. In this work, neat carbon films were fabricated directly from few-layer graphene sheets, avoiding rGOs completely. These essentially graphene-graphene composites were of a metal-like appearance and mechanically flexible, exhibiting superior thermal and electrical transport properties. The observed thermal and electrical conductivities are higher than 220 W/m · K and 85000 S/m, respectively. Some issues in the further development of these mechanically flexible graphene-graphene nanocomposite materials are discussed and so are the associated opportunities.

  4. Geoelectric method applied in correlation between physical characteristics and electrical properties of the soil

    Directory of Open Access Journals (Sweden)

    Antonio Marcelino Silva Filho

    2017-07-01

    Full Text Available This paper presents the study of the relationship between electrical properties and physical characteristics of the soil. Measures of apparent electrical resistivity of the soil were made for different types of soil, varying moisture content gradually while maintaining a constant compaction, and then varying the compaction and relating it to a constant humidity. Development of a correlation surface is proposed in order to identify granulometry of the soil from moisture and compaction measurements. For the study of spatial variability, two areas were chosen to allow the change of moisture content and compaction in order to verify the measurement capacity of apparent electrical resistivity of the soil as methodology to identify change in soil dynamics. Results obtained show correlations among apparent electrical resistivity of the soil, moisture, soil compaction and clay content.

  5. Modulation of Electronic and Optical Anisotropy Properties of ML-GaS by Vertical Electric Field

    Science.gov (United States)

    Guo, Fei; Wu, Yaping; Wu, Zhiming; Ke, Congming; Zhou, Changjie; Chen, Ting; Li, Heng; Zhang, Chunmiao; Fu, Mingming; Kang, Junyong

    2017-06-01

    We investigate the electric-field-dependent optical properties and electronic behaviors of GaS monolayer by using the first-principles calculations. A reversal of the dipole transition from E//c to E⊥c anisotropy is found with a critical external electric field of about 5 V/nm. Decomposed projected band contributions exhibit asymmetric electronic structures in GaS interlayers under the external electric field, which explains the evolution of the absorption preference. Spatial distribution of the partial charge and charge density difference reveal that the strikingly reversed optical anisotropy in GaS ML is closely linked to the additional crystal field originated from the external electric field. These results pave the way for experimental research and provide a new perspective for the application of the monolayer GaS-based two-dimensional electronic and optoelectronic devices.

  6. MRI-based electric properties tomography with a quasi-Newton approach

    Science.gov (United States)

    Rahimov, Anar; Litman, Amélie; Ferrand, Guillaume

    2017-10-01

    Magnetic resonance electric properties tomography is a non-destructive imaging modality that maps the spatial distribution of the electrical conductivity and permittivity of the human body using standard clinical magnetic resonance imaging systems. From the B_1+ magnetic field maps and the local form of the Maxwell equations, several schemes have been derived to provide direct approximated formulas but they suffer from instabilities. In this paper, we propose to address it as an inverse problem solved by a constrained optimization algorithm where we exploit the weak formulation of the electric Helmholtz equation and a Lagrangian approach. We derive the associated adjoint field equation and employ a quasi-Newton minimization scheme. We also take advantage of a regularisation strategy based on geometrical a priori information for defining large zones into which the electric parameters are known to be piece-wise constant.

  7. Effect of CuO addition on structure and electrical properties of low ...

    Indian Academy of Sciences (India)

    3Sb2/3)0·06(Ni1/2W1/2)0·02-. (Zr0·49Ti0·51)0·92]O3. Effect of the addition on sintering temperature, structure and electrical properties of ceramics was investigated. The piezoelectric ceramics was prepared by solid-state reaction. Sintering ...

  8. Effect of CuO addition on structure and electrical properties of low ...

    Indian Academy of Sciences (India)

    0.06(Ni1/2W1/2)0.02-(Zr0.49Ti0.51)0.92]O3. Effect of the addition on sintering temperature, structure and electrical properties of ceramics was investigated. The piezoelectric ceramics was prepared by solid-state reaction. Sintering experiments ...

  9. Studying Some of Electrical and Mechanical Properties for Kevlar Fiber Reinforced Epoxy

    Science.gov (United States)

    Rafeeq, Sewench N.; Hussein, Samah M.

    2011-12-01

    As ordinary known the ability of synthesizing electrical conducting polymer composites is possible but with poor mechanical properties, for the solution of this problem, we carried out this study in order to obtain that both properties. Three methods were applied for preparing the conductive polyaniline (PANI) composites using Kevlar fiber fabric as substrate for the deposition of the PANI at one time and the prepared composite (EP/Kevlar fiber) at others. The chemical oxidative method was adopted for polymerization of the aniline and simultaneously protonated of PANI with a hydrochloric acid at concentration (1M). Two kinds of oxidation agents (FeCl3.6H2O) and ((NH4)2S2O8) were used. The electrical measurements indicate the effect of each preparation method, kind of oxidant agent and the kind of mat erial which PANI deposited on the electrical results. The conductivity results showed that the prepared composites lie within semiconductors region. Temperature—dependence of electric conductivity results showed semiconductors and conductors behavior of this material within the applied temperature ranges. The mechan ical property (tensile strength) was studied. X-ray diffraction study showed the crystalline structure for EP/Kevlar fiber/PANI composites prepared by the three methods. These results gave optimism to the synthesis of conductive polymer composites with excellent mechanical properties..

  10. Thermal and electrical properties of porphyrin derivatives and their relevance for molecule interferometry

    NARCIS (Netherlands)

    Deachapunya, S.; Stefanov, A.; Berninger, M.; Ulbricht, H.; Reiger, E.; Doltsinis, N.L.; Arndt, M.

    2007-01-01

    The authors present new measurements of thermal and electrical properties for two porphyrin derivatives. They determine their sublimation enthalpy from the temperature dependence of the effusive beam intensity. The authors study H2TPP and Fe(TPP)Cl in matter-wave interferometry. Both molecules have

  11. Mechanical and electrical properties of a polyester resin reinforced with clay-based fillers

    Energy Technology Data Exchange (ETDEWEB)

    Buncianu, Dorel; Jadaneant, Mihai [UPT Timisoara, Timisoara (Romania); Tessier-Doyen, Nicolas; Absi, Joseph [Centre Européen de la Céramique, Limoges Cedex (France); Courreges, Fabien [Laboratoire XLIM, 123, Limoges Cedex (France)

    2017-03-15

    In this study, composite polymer-based materials were fabricated, in which a significant proportion of polyester resin was substituted by low-cost and environmentally-friendly clay-based raw materials. The main objective is to improve mechanical properties while maintaining a reasonable electrical insulating behavior. A homogenized distribution of fillers within the matrix compatible with the processing parameters was obtained up to a maximum added fraction of 20 vol%. Mechanical characterization using uniaxial traction tests and Charpy impact pendulum machine showed that stress-to-rupture can be enhanced of approximately 25 %. In addition, fracture energy was doubled for the best formulation. Dielectric constant was decreased and loss factor was slightly increased when electrical resistivity remained almost constant. In general, the composite materials with metakaolin fillers exhibited higher mechanical properties and greater electrical insulating behavior. Microstructural observation showed the presence of decohesive agglomerates of particles at the interface with the matrix. The mechanical properties were found to be more sensitive than electrical properties to the homogeneity of filler dispersion in the matrix.

  12. Self-assembly and electrical properties of a novel heptameric thiophene-benzothiadiazole based architectures.

    Science.gov (United States)

    Crivillers, Núria; Favaretto, Laura; Zanelli, Alberto; Manet, Ilse; Treier, Matthias; Morandi, Vittorio; Gazzano, Massimo; Samorì, Paolo; Melucci, Manuela

    2012-12-28

    A novel semiconducting benzothiadiazole (BTZ)-thiophene (T) co-oligomer having an unprecedented BTZ-T alternated motif has been synthesized and self-assembled into micrometer sized fibers by simple solution processing. The electrical properties of these low-dimensional architectures have been characterized by integrating them in an organic field-effect transistor.

  13. Crystal orientation on the electrical properties of aTe-nSi ...

    African Journals Online (AJOL)

    The effects of crystal orientation on the electrical properties of heterostructure devices fabricated by vacuum evaporation of tellurium film (aTe) on n-type crystalline silicon wafers (nSt) with surface orientations of (100) and (111) are investigated. Two of the devices are annealed in a vacuum at a temperature of 420K for 0.5 ...

  14. Engineering support activities for the Apollo 17 Surface Electrical Properties Experiment.

    Science.gov (United States)

    Cubley, H. D.

    1972-01-01

    Description of the engineering support activities which were required to ensure fulfillment of objectives specified for the Apollo 17 SEP (Surface Electrical Properties) Experiment. Attention is given to procedural steps involving verification of hardware acceptability to the astronauts, computer simulation of the experiment hardware, field trials, receiver antenna pattern measurements, and the qualification test program.

  15. Electrical properties of Ta2O5 films deposited on ZnO

    Indian Academy of Sciences (India)

    High dielectric constant (high-) Ta2O5 films have been deposited on ZnO/-Si substrate by microwave plasma at 150°C. Structure and composition of the ... The electrical properties of the Ta2O5/ZnO/-Si metal insulator semiconductor (MIS) structures were studied using high frequency capacitance–voltage (–), ...

  16. Inversion of soil electrical conductivity data to estimate layered soil properties

    Science.gov (United States)

    CBulk apparent soil electrical conductivity (ECa) sensors respond to multiple soil properties, including clay content, water content, and salt content (i.e., salinity). They provide a single sensor value for an entire soil profile down to a sensor-dependent measurement depth, weighted by a nonlinear...

  17. Impact of divalent dopant Ca 2 on the electrical properties of ZnO by ...

    Indian Academy of Sciences (India)

    The electrical properties of Zn 1 − x Ca x O ( x = 0 , 0.01 , 0.02 and 0.03) nanoceramics synthesized by solidstate reactionmethod were investigated by complex impedance spectroscopy (CIS) from room temperature to 500 ∘ C. Structural analysis of the synthesized material using the X-ray diffraction technique suggests that ...

  18. Non-Invasive Characterization of Brain Tissue Electrical Properties with MRI

    NARCIS (Netherlands)

    Mandija, Stefano

    2017-01-01

    The study of the electrical properties (EPs) of tissues, i.e. conductivity and permittivity, is of fundamental importance to understand the biophysical interactions and the effects of electromagnetic fields on our body, such as those produced by MRI scanners or by Transcranial Magnetic Stimulators

  19. Microstructure and Electrical Properties of AZO/Graphene Nanosheets Fabricated by Spark Plasma Sintering

    OpenAIRE

    Yang, Shuang; Chen, Fei; Shen, Qiang; Enrique J. Lavernia; Zhang, Lianmeng

    2016-01-01

    In this study we report on the sintering behavior, microstructure and electrical properties of Al-doped ZnO ceramics containing 0?0.2 wt. % graphene sheets (AZO-GNSs) and processed using spark plasma sintering (SPS). Our results show that the addition of

  20. A study of the electrical properties of carbon nanofiber polymer composites

    Science.gov (United States)

    Cardoso, Paulo Jorge Magalhaes

    The interest of industry on using carbon nanofibers (CNF) as a possible alternative to carbon nanotubes (CNT) to produce polymer based composites is due to their lower price, the ability to be produced in large amounts and the their usefulness as a reinforcement filler in order to improve the matrix properties such as mechanical, thermal and electrical. Polymers like epoxy resins already have good-to-excellent properties and an extensive range of applications, but the reinforcement with fillers like CNF, which has high aspect ratio (AR) and surface energy, has the potential to extend the range of applications. The Van der Waals interactions between nanofillers, such as CNF, promote the clustering effect which affects their dispersion in the polymer and may interfere with some properties of the nanocomposites. In this sense, it is very important to use appropriate dispersion methods which are able to disentangle the nanofillers to a certain degree, but avoiding the reduction of the nanofibers AR as much as possible. In fact, the methods and conditions of nanocomposites processing have also influence on the filler orientation, dispersion, distribution and aspect ratio. To the present day, there is a lack of complete information in the literature about the relation between structure and properties, in particular electrical properties, for polymer nanocomposites. The main objective of this work is to study the electrical properties of composites based on CNF and epoxy resin using production methods which can be easily implemented in industrial environments and that provide different dispersion levels, investigating therefore the relationship between dispersion level and electrical response. Some of the requirements for such methods are the adaptability to the industrial processes and facilities which allow large scale productions and provide a good relation between quality and cost of the composite materials. In this work, morphological, electrical and

  1. Influence of binding material of PZT coating on microresonator's electrical and mechanical properties

    Science.gov (United States)

    Janusas, Giedrius; Guobiene, Asta; Palevicius, Arvydas; Brunius, Alfredas; Cekas, Elingas; Baltrusaitis, Valentinas; Sakalys, Rokas

    2017-06-01

    Microresonators are fundamental components integrated in hosts of MEMS applications: covering the automotive sector, the telecommunication industry, electronic equipment for surface/material characterization and motion sensing, and etc. The aim of this paper is to investigate the mechanical and electrical properties of PZT film fabricated with three binding materials: polyvinyl butyral (PVB), polymethyl methacrylate (PMMA) and polystyrene (PS) and to evaluate applicability in control of microresonators Q factor. Micro particles of PZT powder were mixed with 20% solution of PVB, PMMA and PS in benzyl alcohol. For investigation of mechanical and electrical properties multilayer cantilevers were made. Obtained PZT and polymer paste was screen printed on copper (thickness 40 μm) using polyester monofilament screen meshes (layer thickness 50 μm) and dried for 30 min at 100°C. Electric dipoles of the PZT particles in composite material were aligned using high voltage generator (5 kV) and a custom-made holder. Electric field was held for 30 min. Surfaces of the applied films were investigated by Atomic Force Microscope NanoWizard(R)3 NanoScience. Dynamic and electrical characteristics of the multilayer were investigated using laser triangular displacement sensor LK-G3000. The measured vibration amplitude and generated electrical potential was collected with USB oscilloscope PicoScope 3424. As the results showed, these cantilevers were able to transform mechanical strain energy into electric potential and, v.v. However, roughness of PZT coatings with PMMA and PS were higher, what could be the reason of the worse quality of the top electrode. However, the main advantage of the created composite piezoelectric material is the possibility to apply it on any uniform or non-uniform vibrating surface and to transform low frequency vibrations into electricity.

  2. Electrical and structural properties of nano-crystalline silicon intrinsic layers for nano-crystalline silicon solar cells prepared by very high frequency plasma chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, P.; Zhu, F. [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Colorado 80401 (United States); Madan, A. [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Colorado 80401 (United States); MVSystems Inc, Golden Colorado 80401 (United States)

    2008-07-15

    Thin silicon intrinsic layers were deposited in the amorphous to nano-crystalline transition regime to investigate their structural and optoelectrical properties using the very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. Optical emission spectroscopy (OES) was primarily used to monitor the plasma properties during the deposition. The ratio H{alpha}/Si{sup *}, estimated from OES spectra, is closely related to the microstructure of the films. With the increasing plasma power from 10 to 50 W, the ratio H{alpha}/Si{sup *} increases leading to nano-crystalline films. The ratio H{alpha}/Si{sup *} decreases with the increase of process gas pressure at constant power of 15 and 30 W. The films were nano-crystalline at low pressure and became amorphous at high pressure. (author)

  3. The Electrical and Optical Properties of Organometal Halide Perovskites Relevant to Optoelectronic Performance

    KAUST Repository

    Adinolfi, Valerio

    2017-10-12

    Organometal halide perovskites are under intense study for use in optoelectronics. Methylammonium and formamidinium lead iodide show impressive performance as photovoltaic materials; a premise that has spurred investigations into light-emitting devices and photodetectors. Herein, the optical and electrical material properties of organometal halide perovskites are reviewed. An overview is given on how the material composition and morphology are tied to these properties, and how these properties ultimately affect device performance. Material attributes and techniques used to estimate them are analyzed for different perovskite materials, with a particular focus on the bandgap, mobility, diffusion length, carrier lifetime, and trap-state density.

  4. Effect of the Addition of Carbon Nanomaterials on Electrical and Mechanical Properties of Wood Plastic Composites

    Directory of Open Access Journals (Sweden)

    Xingli Zhang

    2017-11-01

    Full Text Available Wood Plastic Composites (WPCs are a new generation of green composites that could optimize the use of harvested trees and increase the entire value chain. In this study, the electrical and mechanical properties of WPCs containing carbon blacks (CB, flake graphite (FG and carbon nanotubes (CNTs have been investigated. The electrical property of WPCs is improved significantly owing to the introduction of these carbon nanomaterial fillers. The volume and surface resistivity values of the investigated composites all obviously decreased with the increase in filler content, especially CNTs, which displayed the most satisfactory results. Based on a series of laboratory experiments carried out to investigate the mechanical performance, it can be concluded that the addition of the carbon nanomaterial fillers decreases the mechanical properties of WPCs slightly with the increase in filler content because of the weak interfacial interactions between the fillers and polymer matrix.

  5. The magnetic, electrical and structural properties of copper-permalloy alloys

    Science.gov (United States)

    Qader, Makram A.; Vishina, Alena; Yu, Lei; Garcia, Cougar; Singh, R. K.; Rizzo, N. D.; Huang, Mengchu; Chamberlin, Ralph; Belashchenko, K. D.; van Schilfgaarde, Mark; Newman, N.

    2017-11-01

    Copper-permalloy [Cu1-x(Ni80Fe20)x] alloy films were deposited by co-sputtering and their chemical, structural, magnetic, and electrical properties were characterized. These films are found to have favorable weak ferromagnetic properties for low temperature magnetoelectronic applications. Our results show that by varying the composition, the saturation magnetization (Ms) can be tuned from 700 emu/cm3 to 0 and the Curie temperature (Tc), can be adjusted from 900 K to 0 K. The Ms and Tc are found to scale linearly between x = 25% and 100%. Electronic structure calculations are used to provide a strong fundamental understanding of the mechanisms responsible for establishing the observed electrical and magnetic properties. The theoretical results also show that the introduction of Cu into the permalloy lattice results in very strong spin scattering in the minority spin channel, with only moderate interactions in the majority channel.

  6. Structural, Optical and Electrical Properties of Zinc Oxide Layers Produced by Pulsed Laser Deposition Method.

    Science.gov (United States)

    Wisz, G; Virt, I; Sagan, P; Potera, P; Yavorskyi, R

    2017-12-01

    The structural, optical, and electrical properties of zinc oxide (ZnO) layers manufactured at different process conditions were investigated. ZnO epitaxial layers were grown on silicon, glass, and ITO/glass substrates by pulsed laser deposition (PLD) technique. The influence of power beam, substrate temperature, and deposition time on films properties was analysed. Morphological features of the film surface were investigated by scanning electron microscopy. A structural study shown planar orientation of films at low temperatures of substrate, but the columnar type of growth originated in temperature enhances. Electrical properties were determined in the temperature range 300-500 K. It was shown that the type of films conductivity is metallic and it is limited by charge transfer across grain boundaries.

  7. Effect of solar and magnetic activity on VHF scintillations near the equatorial anomaly crest

    Directory of Open Access Journals (Sweden)

    R. P. Singh

    2004-09-01

    Full Text Available The VHF amplitude scintillation recorded during the period January 1991 to December 1993 in the declining phase of a solar cycle and April 1998 to December 1999 in the ascending phase of the next solar cycle at Varanasi (geogr. lat.=25.3°, long.=83.0°, dip=37°N have been analyzed to study the behavior of ionospheric irregularities during active solar periods and magnetic storms. It is shown that irregularities occur at arbitrary times and may last for <30min. A rise in solar activity increases scintillations during winter (November-February and near equinoxes (March-April; September-October, whereas it depresses the scintillations during the summer (May-July. In general, the role of magnetic activity is to suppress scintillations in the pre-midnight period and to increase it in the post-midnight period during equinox and winter seasons, whilst during summer months the effect is reversed. The pre-midnight scintillation is sometimes observed when the main phase of Dst corresponds to the pre-midnight period. The annual variation shows suppression of scintillations on disturbed days, both during pre-midnight and post-midnight period, which becomes more effective during years of high solar activity. It is observed that for magnetic storms for which the recovery phase starts post-midnight, the probability of occurrence of irregularities is enhanced during this time. If the magnetic storm occurred during daytime, then the probability of occurrence of scintillations during the night hours is decreased. The penetration of magnetospheric electric fields to the magnetic equator affects the evolution of low-latitude irregularities. A delayed disturbance dynamo electric field also affects the development of irregularities.

  8. Electrical transport properties of La1-xSrxCoO3 thin films

    Science.gov (United States)

    Liu, Bin; Wang, Yiqian; Liu, Guiju; Feng, Honglei; Yang, Huaiwen; Sun, Jirong

    2016-10-01

    The electrical transport properties of La1-xSrxCoO3 (LSCO) thin films were investigated in this paper. As x increased up to 0.3, the electrical transport mechanism transferred from variable range hopping to double-exchange and the film simultaneously turned from an insulator into a conductor. Different from the bulk materials, the maximum conductivity of the film appeared at x = 0.3. A novel electrical transport model was proposed to explain this unconventional phenomenon. Besides, the effects of doped Sr and oxygen vacancies on the electrical transport properties were clarified by investigated the transport behaviors of the LaCoO3, La0.7S0.3CoO3, and La0.7S0.3CoO3-δ films. We found that, when Sr was doped into the LaCoO3 film, the insulating film turns into a conductor; when oxygen atoms were removed from the La0.7S0.3CoO3 film, the conducting film goes back to an insulator. Our work could shed light on the electrical transport mechanism of the LSCO films.

  9. Estimation of Soil Electrical Properties in a Multilayer Earth Model with Boundary Element Formulation

    Directory of Open Access Journals (Sweden)

    T. Islam

    2012-01-01

    Full Text Available This paper presents an efficient model for estimation of soil electric resistivity with depth and layer thickness in a multilayer earth structure. This model is the improvement of conventional two-layer earth model including Wenner resistivity formulations with boundary conditions. Two-layer soil model shows the limitations in specific soil characterizations of different layers with the interrelationships between soil apparent electrical resistivity (ρ and several soil physical or chemical properties. In the multilayer soil model, the soil resistivity and electric potential at any points in multilayer anisotropic soil medium are expressed according to the variation of electric field intensity for geotechnical investigations. For most soils with varying layers, multilayer soil resistivity profile is therefore more suitable to get soil type, bulk density of compacted soil and to detect anomalous materials in soil. A boundary element formulation is implemented to show the multilayer soil model with boundary conditions in soil resistivity estimations. Numerical results of soil resistivity ratio and potential differences for different layers are presented to illustrate the application, accuracy, and efficiency of the proposed model. The nobility of the research is obtaining multilayer soil characterizations through soil electric properties in near surface soil profile.

  10. Influence of carbon nanoparticle modification on the mechanical and electrical properties of epoxy in small volumes.

    Science.gov (United States)

    Leopold, Christian; Augustin, Till; Schwebler, Thomas; Lehmann, Jonas; Liebig, Wilfried V; Fiedler, Bodo

    2017-11-15

    The influence of nanoparticle morphology and filler content on the mechanical and electrical properties of carbon nanoparticle modified epoxy is investigated regarding small volumes. Three types of particles, representing spherical, tubular and layered morphologies are used. A clear size effect of increasing true failure strength with decreasing volume is found for neat and carbon black modified epoxy. Carbon nanotube (CNT) modified epoxy exhibits high potential for strength increase, but dispersion and purity are critical. In few layer graphene modified epoxy, particles are larger than statistically distributed defects and initiate cracks, counteracting any size effect. Different toughness increasing mechanisms on the nano- and micro-scale depending on particle morphology are discussed based on scanning electron microscopy images. Electrical percolation thresholds in the small volume fibres are significantly higher compared to bulk volume, with CNT being found to be the most suitable morphology to form electrical conductive paths. Good correlation between electrical resistance change and stress strain behaviour under tensile loads is observed. The results show the possibility to detect internal damage in small volumes by measuring electrical resistance and therefore indicate to the high potential for using CNT modified polymers in fibre reinforced plastics as a multifunctional, self-monitoring material with improved mechanical properties. Copyright © 2017. Published by Elsevier Inc.

  11. Electrical Resistivity Based Empirical Model For Delineating Some Selected Soil Properties On Sandy-Loam Soil

    Directory of Open Access Journals (Sweden)

    Joshua

    2015-08-01

    Full Text Available Electrical Resistivity ER survey was conducted on a Sandy-loam soil with a view to evaluate some selected soil properties. Electrical Resistivity was measured from the soil surface at 0 0.3 m ER30 and 0 0.9 m ER90 soil depths using multi-electrode Wenner array and Miller 400D resistance meter. Soil samples were collected to a depth 0.3 m at points where ER was measured and analyzed for properties such as Organic Matter OM Cation Exchange Capacity CEC Soil Water Content SWC Sand Silt and Clay contents using standard methods. The results indicated that lower ER areas exhibit higher content of soil properties than higher ER areas. The ER90 correlates insignificantly to the soil properties while ER30 correlates significantly to the soil properties except clay r 0.63 - 0.75. The relationship between ER30 and soil properties were best fitted to multiple linear regression R2 0.90 and Boltzmann distribution R2 0.80 - 0.84. The study indicates the ability of ER to delineate some soil properties influencing yield on sandy-loam soil. This will help farmers take decisions that can improve yields.

  12. CSI-EPT: A Contrast Source Inversion Approach for Improved MRI-Based Electric Properties Tomography.

    Science.gov (United States)

    Balidemaj, Edmond; van den Berg, Cornelis A T; Trinks, Johan; van Lier, Astrid L H M W; Nederveen, Aart J; Stalpers, Lukas J A; Crezee, Hans; Remis, Rob F

    2015-09-01

    Electric properties tomography (EPT) is an imaging modality to reconstruct the electric conductivity and permittivity inside the human body based on B1(+) maps acquired by a magnetic resonance imaging (MRI) system. Current implementations of EPT are based on the local Maxwell equations and assume piecewise constant media. The accuracy of the reconstructed maps may therefore be sensitive to noise and reconstruction errors occur near tissue boundaries. In this paper, we introduce a multiplicative regularized CSI-EPT method (contrast source inversion-electric properties tomography) where the electric tissue properties are retrieved in an iterative fashion based on a contrast source inversion approach. The method takes the integral representations for the electromagnetic field as a starting point and the tissue parameters are obtained by iteratively minimizing an objective function which measures the discrepancy between measured and modeled data and the discrepancy in satisfying a consistency equation known as the object equation. Furthermore, the objective function consists of a multiplicative Total Variation factor for noise suppression during the reconstruction process. Finally, the presented implementation is able to simultaneously include more than one B1(+) data set acquired by complementary RF excitation settings. We have performed in vivo simulations using a female pelvis model to compute the B1(+) fields. Three different RF excitation settings were used to acquire complementary B1(+) fields for an improved overall reconstruction. Numerical results illustrate the improved reconstruction near tissue boundaries and the ability of CSI-EPT to reconstruct small tissue structures.

  13. Electrical Properties of Isolated Cardiomyocytes in a Rat Model of Thiamine Deficiency

    Directory of Open Access Journals (Sweden)

    Artur Santos-Miranda

    2015-03-01

    Full Text Available In modern society, thiamine deficiency (TD remains an important medical condition linked to altered cardiac function. There have been contradictory reports about the impact of TD on heart physiology, especially in the context of cardiac excitability. In order to address this particular question, we used a TD rat model and patch-clamp technique to investigate the electrical properties of isolated cardiomyocytes from epicardium and endocardium. Neither cell type showed substantial differences on the action potential waveform and transient outward potassium current. Based on our results we can conclude that TD does not induce major electrical remodeling in isolated cardiac myocytes in either endocardium or epicardium cells.

  14. Investigation of Mechanical and Electrical Properties of Hybrid Composites Reinforced with Carbon Nanotubes and Micrometer-Sized Silica Particles

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Yun; You, Byeong Il; Ahn, Ji Ho; Lee, Gyo Woo [Chonbuk Nat’l Univ., Junju (Korea, Republic of)

    2016-12-15

    In this study, to enhance the electrical insulation of composite specimens in addition to the improved mechanical properties, the epoxy composite were reinforced with carbon nanotubes and silica particles. Tensile strength, Young's modulus, dynamic mechanical behavior, and electrical resistivity of the specimens were measured with varied contents of the two fillers. The mechanical and electrical properties were discussed, and the experimental results related to the mechanical properties of the specimens were compared with those from several micromechanics models. The hybrid composites specimens with 0.6 wt% of carbon nanotubes and 50 wt% of silica particles showed improved mechanical properties, with increase in tensile strength and Young's modulus up to 11% and 35%, respectively, with respect to those of the baseline specimen. The electrical conductivity of the composite specimens with carbon nanotubes filler also improved. Further, the electrical insulation of the hybrid composites specimens with the two fillers improved in addition to the improvement in mechanical properties.

  15. Comparison of properties of silver-metal oxide electrical contact materials

    Directory of Open Access Journals (Sweden)

    Ćosović V.

    2012-01-01

    Full Text Available Changes in physical properties such as density, porosity, hardness and electrical conductivity of the Ag-SnO2 and Ag-SnO2In2O3 electrical contact materials induced by introduction of metal oxide nanoparticles were investigated. Properties of the obtained silver-metal oxide nanoparticle composites are discussed and presented in comparison to their counterparts with the micro metal oxide particles as well as comparable Ag-SnO2WO3 and Ag-ZnO contact materials. Studied silvermetal oxide composites were produced by powder metallurgy method from very fine pure silver and micro- and nanoparticle metal oxide powders. Very uniform microstructures were obtained for all investigated composites and they exhibited physical properties that are comparable with relevant properties of equivalent commercial silver based electrical contact materials. Both Ag-SnO2 and Ag- SnO2In2O3 composites with metal oxide nanoparticles were found to have lower porosity, higher density and hardness than their respective counterparts which can be attributed to better dispersion hardening i.e. higher degree of dispersion of metal oxide in silver matrix.

  16. Electrical properties of undoped zinc oxide nanostructures at different annealing temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, M. F., E-mail: babaibaik2002@yahoo.com; Zainol, M. N., E-mail: nizarzainol@yahoo.com; Hannas, M., E-mail: mhannas@gmail.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Mamat, M. H., E-mail: mhmamat@salam.uitm.edu.my; Rusop, Mohamad, E-mail: rusop@salam.uitm.edu.my [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia); Rahman, S. A., E-mail: saadah@um.edu.my [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Low Dimensional Materials Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-07-06

    This project has been focused on the electrical and optical properties respectively on the effect of Undoped zinc oxide (ZnO) thin films at different annealing temperature which is varied 400 °C, 450 °C, 500 °C, and 550 °C.Undoped ZnO solutions were deposited onto the glass substrates using sol-gel spin coating method. This project was involved with three phases, which are thin films preparation, deposition and characterization. The thin films were characterized using Current Voltage (I-V) measurement and UV-vis-NIR spectrophotometer for electrical properties and optical properties. The electrical properties show that the resistivity is the lowest at 500 °C which its resistivity is 5.36 × 10{sup 4} Ωcm{sup −1}. The absorption coefficient spectrum obtained from UV-Vis-NIR spectrophotometer measurement shows all films exhibit very low absorption in the visible (400-800 nm) and near infrared (NIR) (>800 nm) range but exhibit high absorption in the UV range.

  17. Electrical properties of Mg doped ZnO nanostructure annealed at different temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, R., E-mail: ruziana12@gmail.com; Mamat, M. H., E-mail: hafiz-030@yahoo.com; Rusop, M., E-mail: nanouitm@gmail.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z., E-mail: Zurai142@salam.uitm.edu.my [NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    In this work, ZincOxide (ZnO) nanostructures doped with Mg were successfully grown on the glass substrate. Magnesium (Mg) metal element was added in the ZnO host which acts as a doping agent. Different temperature in range of 250°C to 500°C was used in order to investigate the effect of annealing temperature of ZnO thin films. Field Emission Scanning Electron Microscopy (FESEM) was used to investigate the physical characteristic of ZnO thin films. FESEM results have revealed that ZnO nanorods were grown vertically aligned. The structural properties were determined by using X-Ray Diffraction (XRD) analysis. XRD results showed Mg doped ZnO thin have highest crystalinnity at 500°C annealing temperature. The electrical properties were investigating by using Current-Voltage (I-V) measurement. I-V measurement showed the electrical properties were varied at different annealing temperature. The annealing temperature at 500°C has the highest electrical conductance properties.

  18. Electrical properties of tin-doped zinc oxide nanostructures doped at different dopant concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Nasir, M. F., E-mail: babaibaik2002@yahoo.com; Zainol, M. N., E-mail: nizarzainol@yahoo.com; Hannas, M., E-mail: mhannas@gmail.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Mamat, M. H., E-mail: mhmamat@salam.uitm.edu.my; Rusop, Mohamad, E-mail: rusop@salam.uitm.edu.my [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia); Rahman, S. A., E-mail: saadah@um.edu.my [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Low Dimensional Materials Research Centre, Physics Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-07-06

    This project has been focused on the electrical and optical properties respectively on the effect of Tin doped zinc oxide (ZnO) thin films at different dopant concentrations. These thin films were doped with different Sn dopant concentrations at 1 at%, 2 at%, 3 at%, 4 at% and 5 at% was selected as the parameter to optimize the thin films quality while the annealing temperature is fixed 500 °C. Sn doped ZnO solutions were deposited onto the glass substrates using sol-gel spin coating method. This project was involved with three phases, which are thin films preparation, deposition and characterization. The thin films were characterized using Current Voltage (I-V) measurement and ultraviolet-visible-near-infrared (UV-vis-NIR) spectrophotometer (Perkin Elmer Lambda 750) for electrical properties and optical properties. The electrical properties show that the resistivity is the lowest at 4 at% Sn doping concentration with the value 3.08 × 10{sup 3} Ωcm{sup −1}. The absorption coefficient spectrum obtained shows all films exhibit very low absorption in the visible (400-800 nm) and near infrared (NIR) (>800 nm) range but exhibit high absorption in the UV range.

  19. In doped CdO films: Electrical, optical, structural and surface properties

    Energy Technology Data Exchange (ETDEWEB)

    Kose, Salih; Atay, Ferhunde; Akyuz, Idris [Eskisehir Osmangazi University, Department of Physics, Art and Science Faculty, 26480 Eskisehir (Turkey); Bilgin, Vildan [Canakkale Onsekiz Mart University, Department of Physics, 17100 Canakkale (Turkey)

    2009-06-15

    Recently, there has been a lot of work on the production and investigation of the physical properties of Transparent Conducting Oxide (TCO) materials which have common application area in photovoltaic solar cells and some optoelectronic devices. In this work, CdO film which is a material belongs to TCO family has been produced by Ultrasonic Spray Pyrolysis technique on microscope glass substrates at the substrate temperature of 250 {+-} 5 C. Electrical, optical, structural and surface properties of undoped and In doped (at 1.3 and 5%) CdO films and the effect of In doping percentage on the physical properties of CdO films have been investigated. It has been determined that electrical conductivity of CdO film is high and this value has been decreased by In doping. After the optical investigations, it has been observed that the transmittances of the films are about 30% and decreased dramatically by In doping. XRD investigations showed that, films have polycrystalline structure and good crystallinity levels. It has been found that In element hasn't got an important effect on the morphology of the films after the examination of surface micrographs. It has been determined that Cd and O elements are present in the solid film by using EDS. After all investigations, it has been concluded that In doping has an important effect on the electrical, optical, structural and surface properties of CdO films. (author)

  20. Polypropylene Carbon Nanotubes Nanocomposites: Combined Influence of Block Copolymer Compatibilizer and Melt Annealing on Electrical Properties

    Directory of Open Access Journals (Sweden)

    Aline Emplit

    2017-01-01

    Full Text Available We study the influence of melt annealing and the presence of a block copolymer compatibilizer on the electrical properties of polypropylene carbon nanotubes (CNT nanocomposites from the DC limit to microwave frequencies and link it to the morphological details. We show that the compatibilizer concentration controls three types of morphologies: separate CNT agglomerates, a network of well dispersed but interconnected CNT, and individualized but separate nanotubes. This explains why conductivity reaches an optimum over the whole frequency range at a low compatibilizer concentration. We model the corresponding structures by a semiquantitative schematic equivalent electrical circuit. A key outcome of the work is the understanding and control of dispersion mechanisms in order to optimize the electrical performances for efficient EMI shielding depending on the targeted frequency range.

  1. Effect of an electric field on the properties of BN Möbius stripes

    Energy Technology Data Exchange (ETDEWEB)

    Lemos de Melo, J. [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900 João Pessoa, PB (Brazil); Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900 João Pessoa, PB (Brazil); Kaschny, J.R. [Instituto Federal da Bahia, Campus Vitória da Conquista, Av. Amazonas 3150, 45075-265 Vitória da conquista, BA (Brazil)

    2014-09-15

    In the present work, we present a first-principles study on the effects of an external electric field on the structural stability and electronic properties of boron nitride Möbius stripes with armchair and zigzag chirality. The calculation results indicate that the gap energy can be remarkably reduced by the application of an external field. Such reduction is in principle attributed to the occurrence of Stark effect, which significance depends on the orientation of the applied field relative to the stripe axis. Moreover, the electric field produces significant changes on dipole momentum of the structure and induces a negative shift on the calculated total energy, reducing the obtained formation energy. - Highlights: • The gap energy is remarkably reduced by the application of an external field. • The electric field produces significant changes on dipole momentum. • The field induces a negative shift on the total energy due to Stark effect.

  2. Mechanical and Electrical Properties of Palladium-Coated Copper Wires with Flash Gold

    Science.gov (United States)

    Chang, Chia-Yun; Hung, Fei-Yi; Lui, Truan-Sheng

    2017-07-01

    Palladium-coated copper wire with flash gold (PCA) is a fine wire with an oxidation resistance layer. A new sulfidation test has been assessed in this work, confirming that PCA wires show better sulfidation corrosion resistance than either palladium-coated or bare copper wires. The sulfided surface of PCA was analyzed, along with its bonding strength and electrical properties. The metallurgic mechanism for formation of free air balls during the electric flame-off (EFO) process was identified. The flash gold layer of PCA wires can improve certain shortcomings, including: (1) efficiently promoting sulfidation corrosion resistance, (2) solving the problem of palladium segregation during the EFO process, (3) reducing the starting voltage, and (4) stabilizing the electrical resistivity of the bonding interface.

  3. Modeling of skin cooling, blood flow, and optical properties in wounds created by electrical shock

    Science.gov (United States)

    Nguyen, Thu T. A.; Shupp, Jeffrey W.; Moffatt, Lauren T.; Jordan, Marion H.; Jeng, James C.; Ramella-Roman, Jessica C.

    2012-02-01

    High voltage electrical injuries may lead to irreversible tissue damage or even death. Research on tissue injury following high voltage shock is needed and may yield stage-appropriate therapy to reduce amputation rate. One of the mechanisms by which electricity damages tissue is through Joule heating, with subsequent protein denaturation. Previous studies have shown that blood flow had a significant effect on the cooling rate of heated subcutaneous tissue. To assess the thermal damage in tissue, this study focused on monitoring changes of temperature and optical properties of skin next to high voltage wounds. The burns were created between left fore limb and right hind limb extremities of adult male Sprague-Dawley rats by a 1000VDC delivery shock system. A thermal camera was utilized to record temperature variation during the exposure. The experimental results were then validated using a thermal-electric finite element model (FEM).

  4. Ab initio study of opto electric properties of the molecules pyrimethamine and sulfadoxine

    Directory of Open Access Journals (Sweden)

    S. Nouemo

    2015-10-01

    Full Text Available The optical and electrical properties of the molecules pyrimethamine and sulfadoxine in gas phase and in different mediums (water and ethanol were calculated using density-functional theory at the B3LYP level and the Restricted Hartree–Fock (RHF level by employing 6-311++G∗∗ basis set. The dipole moment, polarization density, the electric susceptibility, the refractive index, the dielectric constant and the magnitude of the displacement vector of these molecules have been calculated. Small values of polarization density, dielectric constant, magnitude of the displacement vector, high values of electric susceptibility, refractive index and small HOMO–LUMO energy gaps of these molecules show that, these molecules have very good opto electronic applications.

  5. Remodeling of cardiac passive electrical properties and susceptibility to ventricular and atrial arrhythmias

    Directory of Open Access Journals (Sweden)

    Stefan eDhein

    2014-11-01

    Full Text Available Coordinated electrical activation of the heart is essential for the maintenance of a regular cardiac rhythm and effective contractions. Action potentials spread from one cell to the next via gap junction channels. Because of the elongated shape of cardiomyocytes, longitudinal resistivity is lower than transverse resistivity causing electrical anisotropy. Moreover, non-uniformity is created by clustering of gap junction channels at cell poles and by non-excitable structures such as collagenous strands, vessels or fibroblasts. Structural changes in cardiac disease often affect passive electrical properties by increasing non-uniformity and altering anisotropy. This disturbs normal electrical impulse propagation and is, consequently, a substrate for arrhythmia. However, to investigate how these structural changes lead to arrhythmias remains a challenge. One important mechanism, which may both cause and prevent arrhythmia, is the mismatch between current sources and sinks. Propagation of the electrical impulse requires a sufficient source of depolarizing current. In the case of a mismatch, the activated tissue (source is not able to deliver enough depolarizing current to trigger an action potential in the non-activated tissue (sink. This eventually leads to conduction block. It has been suggested that in this situation a balanced geometrical distribution of gap junctions and reduced gap junction conductance may allow successful propagation. In contrast, source-sink mismatch can prevent spontaneous arrhythmogenic activity in a small number of cells from spreading over the ventricle, especially if gap junction conductance is enhanced. Beside gap junctions, cell geometry and non-cellular structures strongly modulate arrhythmogenic mechanisms. The present review elucidates these and other implications of passive electrical properties for cardiac rhythm and arrhythmogenesis.

  6. Letter to the Editor: Complete maps of the aspect sensitivity of VHF atmospheric radar echoes

    Directory of Open Access Journals (Sweden)

    R. M. Worthington

    1999-08-01

    Full Text Available Using the MU radar at Shigaraki, Japan (34.85°N, 136.10°E, we measure the power distribution pattern of VHF radar echoes from the mid-troposphere. The large number of radar beam-pointing directions (320 allows the mapping of echo power from 0° to 40° from zenith, and also the dependence on azimuth, which has not been achieved before at VHF wavelengths. The results show how vertical shear of the horizontal wind is associated with a definite skewing of the VHF echo power distribution, for beam angles as far as 30° or more from zenith, so that aspect sensitivity cannot be assumed negligible at any beam-pointing angle that most existing VHF radars are able to use. Consequently, the use of VHF echo power to calculate intensity of atmospheric turbulence, which assumes only isotropic backscatter at large beam zenith angles, will sometimes not be valid.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence; instruments and techniques

  7. Robust mapping of electrical properties of graphene from terahertz time-domain spectroscopy with timing jitter correction

    DEFF Research Database (Denmark)

    Whelan, Patrick Rebsdorf; Iwaszczuk, Krzysztof; Wang, Ruizhi

    2017-01-01

    from internal reflections in a substrate, we are able to extract electrical properties irrespective of random time delays between pulses emitted in a THz-TDS setup. If such time delays are not accounted for they can significantly influence the extracted properties of the material. The technique...... is useful for a robust determination of electrical properties from THz-TDS measurements and is compatible with substrate materials where transients from internal reflections are well-separated in time....

  8. Structural Characterization and Infrared and Electrical Properties of the New Inorganic-Organic Hybrid Compound

    Directory of Open Access Journals (Sweden)

    A. Oueslati

    2013-01-01

    Full Text Available New inorganic-organic hybrid [(C3H74N]2Hg2Cl6 compound was obtained and characterised by single-crystal X-ray diffraction, infrared, and impedance spectroscopy. The latter crystallizes in the monoclinic system (space group C 2/c, with the following unit cell dimensions: (1 Å, (6 Å, (2 Å, and (2. Besides, its structure was solved using 84860 independent reflections leading to . Electrical properties of the material were studied using impedance spectroscopic technique at different temperatures in the frequency range of 209 Hz to 5 MHz. Detailed analysis of the impedance spectrum suggested that the electrical properties of the material are strongly temperature-dependent. The Nyquist plots clearly showed the presence of bulk and grain boundary effect in the compound.

  9. Doping Effect of Graphene Nanoplatelets on Electrical Insulation Properties of Polyethylene: From Macroscopic to Molecular Scale

    Directory of Open Access Journals (Sweden)

    Ziang Jing

    2016-08-01

    Full Text Available The doping effect of graphene nanoplatelets (GNPs on electrical insulation properties of polyethylene (PE was studied by combining experimental and theoretical methods. The electric conduction properties and trap characteristics were tested for pure PE and PE/GNPs composites by using a direct measurement method and a thermal stimulated current (TSC method. It was found that doping smaller GNPs is more beneficial to decrease the conductivity of PE/GNPs. The PE/GNPs composite with smaller size GNPs mainly introduces deep energy traps, while with increasing GNPs size, besides deep energy traps, shallow energy traps are also introduced. These results were also confirmed by density functional theory (DFT and the non-equilibrium Green’s function (NEGF method calculations. Therefore, doping small size GNPs is favorable for trapping charge carriers and enhancing insulation ability, which is suggested as an effective strategy in exploring powerful insulation materials.

  10. Numerical modeling of non-woven fiber mats: Their effective mechanical and electrical properties

    Science.gov (United States)

    Tuncer, Enis; L'Abee, Roy

    2015-06-01

    Numerical simulations on non-woven fibrous, porous structures were performed to determine material design space for energy storage device (battery and ultra-capacitor) separators. Material simulations were performed initially with a commercial program called GeoDict using its demo version. Later, in-house computational tools were developed and employed. The numerical routines were created to model mechanical and electrical properties of porous structures. The tools were built as a pre-processor for a commercial finite element package. Effective properties were estimated in the post-processing phase using the current and stress distributions. No multi-physics assumptions were considered to couple electrical and mechanical fields at this stage. The numerical results between two numerical platforms, GeoDict and in-house tools. Regions of interest in porosity for battery separators are discussed.

  11. The electrical properties of bulk GaN crystals grown by HVPE

    Science.gov (United States)

    Gu, Hong; Ren, Guoqiang; Zhou, Taofei; Tian, Feifei; Xu, Yu; Zhang, Yumin; Wang, Mingyue; Wang, Jianfeng; Xu, Ke

    2016-02-01

    The electrical properties of high-quality bulk GaN crystals grown by Hydride Vapor Phase Epitaxy (HVPE) were investigated. The series of samples were sliced from the same bulk crystal grown by HVPE. The crystal quality of the samples was characterized by the cathode luminescence (CL) and high resolution X-ray diffraction measurements (HRXRD), the evaluated dislocation density ranges from 2.4×106 cm-2 to 2.3×105 cm-2. The temperature-dependent Hall measurements were conducted and the results were analyzed theoretically. The results suggest that with low dislocation density (≤106 cm-2) and low carrier concentration (≤1017 cm-3), the impurity concentration should play an important role in the electrical properties. With the impurity concentration decreasing, the hall mobility increases from 619 to 1160 cm2/(V s), and the carrier concentration decreases from 5.42×1016 cm-3 to 1.31×1016 cm-3.

  12. Doping Effect of Graphene Nanoplatelets on Electrical Insulation Properties of Polyethylene: From Macroscopic to Molecular Scale.

    Science.gov (United States)

    Jing, Ziang; Li, Changming; Zhao, Hong; Zhang, Guiling; Han, Baozhong

    2016-08-10

    The doping effect of graphene nanoplatelets (GNPs) on electrical insulation properties of polyethylene (PE) was studied by combining experimental and theoretical methods. The electric conduction properties and trap characteristics were tested for pure PE and PE/GNPs composites by using a direct measurement method and a thermal stimulated current (TSC) method. It was found that doping smaller GNPs is more beneficial to decrease the conductivity of PE/GNPs. The PE/GNPs composite with smaller size GNPs mainly introduces deep energy traps, while with increasing GNPs size, besides deep energy traps, shallow energy traps are also introduced. These results were also confirmed by density functional theory (DFT) and the non-equilibrium Green's function (NEGF) method calculations. Therefore, doping small size GNPs is favorable for trapping charge carriers and enhancing insulation ability, which is suggested as an effective strategy in exploring powerful insulation materials.

  13. Optical and electrical properties of mechanochemically synthesized nanocrystalline delafossite CuAlO2.

    Science.gov (United States)

    Prakash, T; Prasad, K Padma; Ramasamy, S; Murty, B S

    2008-08-01

    Nanocrystalline p-type semiconductor copper aluminum oxide (CuAlO2) has been synthesized by mechanical alloying using freshly prepared Cu2O and alpha-AlO2O3 nanocrystals in toluene medium. A study on structural property performed with different alloying and post annealing durations, by X-ray diffraction (XRD) reveals the formation of single phase with average crystallite size approximately 45 nm. Optical absorbance onset at 364.5 nm confirms its wide band gap nature (E(g) = 3.4 eV) and the fluorescence emission behaviour (390 nm) confirms its direct band type transition. The activation energy for electrical conduction has been calculated by Arrhenius plots using impedance measurement. Both grain and grain boundary conductivity takes place with almost equal activation energies of approximately 0.45 eV. The paper discusses synthesis, structural, optical and electrical properties of delafossite CuAlO2 in detail.

  14. Electrical, optical, and electronic properties of Al:ZnO films in a wide doping range

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, Ilaria; Valeri, Sergio [CNR, Istituto Nanoscienze, S3, Via G. Campi 213/a, 41125 Modena (Italy); Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, Via G. Campi 213/a, 41125 Modena (Italy); Benedetti, Stefania, E-mail: stefania.benedetti@unimore.it; Bona, Alessandro di [CNR, Istituto Nanoscienze, S3, Via G. Campi 213/a, 41125 Modena (Italy); Lollobrigida, Valerio [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome, Italy and Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Perucchi, Andrea; Di Pietro, Paola [INSTM Udr Trieste-ST and Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Trieste (Italy); Lupi, Stefano [CNR-IOM and Dipartimento di Fisica, Università di Roma Sapienza, P.le Aldo Moro 2, I-00185 Roma (Italy); Torelli, Piero [Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy)

    2015-10-28

    The combination of photoemission spectroscopies, infrared and UV-VIS absorption, and electric measurements has allowed to clarify the mechanisms governing the conductivity and the electronic properties of Al-doped ZnO (AZO) films in a wide doping range. The contribution of defect-related in-gap states to conduction has been excluded in optimally doped films (around 4 at. %). The appearance of gap states at high doping, the disappearance of occupied DOS at Fermi level, and the bands evolution complete the picture of electronic structure in AZO when doped above 4 at. %. In this situation, compensating defects deplete the conduction band and increase the electronic bandgap of the material. Electrical measurements and figure of merit determination confirm the high quality of the films obtained by magnetron sputtering, and thus allow to extend their properties to AZO films in general.

  15. Effect of freezing on electrical properties and quality of thawed chicken breast meat.

    Science.gov (United States)

    Wei, Ran; Wang, Peng; Han, Minyi; Chen, Tianhao; Xu, Xinglian; Zhou, Guanghong

    2017-04-01

    The objective of this research was to study the electrical properties and quality of frozen-thawed chicken breast meat and to investigate the relationship between these parameters at different times of frozen storage. Thawed samples of chicken breast muscles were evaluated after being kept in frozen storage at -18°C for different periods of time (1, 2, 3, 4, 5, 6, 7, and 8 months). The results showed that water-holding capacity (WHC) and protein solubility decreased while thiobarbituric acid-reactive substances content increased with increasing storage time. The impedance module of samples decreased during 8-month frozen storage. Pearson correlation coefficients showed that the impedance change ratio (Q value) was significantly (pprotein solubility, indicating a good relationship between the electrical properties and qualities of frozen-thawed chicken breast meat. Impedance measurement has a potential to assess the quality of frozen chicken meat combining with quality indices.

  16. Theoretical study of electric properties of zig-zag carbon nanotubes at low nitrogen concentration

    Directory of Open Access Journals (Sweden)

    Elsa G. Ordoñez Casanova

    Full Text Available We have performed a comparative study of electrical properties between pristine and nitrogen doped (at low concentration single wall carbon nanotubes (SWNTs, for three zig-zag cases: (6,0, (8,0 and (9,0. The results were obtained through the Density Functional Theory (DFT with the Generalized Gradient Approximation (GGA in the relaxed CC bond length for the long-wavelength limit. The stability of the structures was determined by calculating total energies for the pristine and the N-doped structures. From the calculations of the energy loss function, we probed plasmon peak positions for the proposed quiralities. Keywords: DFT, Carbon nanotubes, Electrical properties

  17. Data on electrical properties of nickel modified potassium polytitanates compacted powders

    Directory of Open Access Journals (Sweden)

    V.G. Goffman

    2015-09-01

    Full Text Available Potassium polytitanates are new promising type of ferroelectric ceramic materials with high ionic conductivity, highly polarizable structure and extremely high permittivity. Its structure is formed by [TiO6] octahedral units to layers with mobile potassium and hydroxonium ions in-between. The treatment in solutions containing nickel ions allows forming heterostructured materials which consist of potassium polytitanate particles intercalated by Ni2+ ions and/or decorated by nickel oxides NiOx. This modification route is fully dependant on solution pH, i.e. in acidic solutions the intercalation process prevails, in alkaline solutions potassium polytitanate is mostly decorated by the oxides. Therefore, electronic structure and electrical properties can be regulated depending on modification conditions, pH and ions concentration. Here we report the data on electric properties of potassium titanate modified in nickel sulfate solutions at different pH.

  18. Hydrothermal temperature effect on crystal structures, optical properties and electrical conductivity of ZnO nanostructures

    Science.gov (United States)

    Dhafina, Wan Almaz; Salleh, Hasiah; Daud, Mohd Zalani; Ghazali, Mohd Sabri Mohd; Ghazali, Salmah Mohd

    2017-09-01

    ZnO is an wide direct band gap semiconductor and possess rich family of nanostructures which turned to be a key role in the nanotechnology field of applications. Hydrothermal method was proven to be simple, robust and low cost among the reported methods to synthesize ZnO nanostructures. In this work, the properties of ZnO nanostructures were altered by varying temperatures of hydrothermal process. The changes in term of morphological, crystal structures, optical properties and electrical conductivity were investigated. A drastic change of ZnO nanostructures morphology and decreases of 002 diffraction peak were observed as the hydrothermal temperature increased. The band gap of samples decreased as the size of ZnO nanostructure increased, whereas the electrical conductivity had no influence on the band gap value but more on the morphology of ZnO nanostructures instead.

  19. Effect of elastic and plastic tensile mechanical loading on the magnetic properties of NGO electrical steel

    Energy Technology Data Exchange (ETDEWEB)

    Leuning, N., E-mail: nora.leuning@iem.rwth-aachen.de [Institute of Electrical Machines, RWTH Aachen University, D-52062 Aachen (Germany); Steentjes, S. [Institute of Electrical Machines, RWTH Aachen University, D-52062 Aachen (Germany); Schulte, M.; Bleck, W. [Steel Institute, RWTH Aachen University, D-52072 Aachen (Germany); Hameyer, K. [Institute of Electrical Machines, RWTH Aachen University, D-52062 Aachen (Germany)

    2016-11-01

    The magnetic properties of non-grain-oriented (NGO) electrical steels are highly susceptible to mechanical stresses, i.e., residual, external or thermal ones. For rotating electrical machines, mechanical stresses are inevitable and originate from different sources, e.g., material processing, machine manufacturing and operating conditions. The efficiency and specific losses are largely altered by different mechanical stress states. In this paper the effect of tensile stresses and plastic deformations on the magnetic properties of a 2.9 wt% Si electrical steel are studied. Particular attention is paid to the effect of magnetic anisotropy, i.e., the influence of the direction of applied mechanical stress with respect to the rolling direction. Due to mechanical stress, the induced anisotropy has to be evaluated as it is related to the stress-dependent magnetostriction constant and the grain alignment. - Highlights: • A detailed look at magnetic anisotropy of FeSi NGO electrical steel. • Study of magnetic behavior under elastic as well as plastic tensile stresses. • Correlation of magnetic behavior with microscopic deformation mechanisms. • Discussion of detrimental and beneficial effects of external stresses. • Loss separation at different polarizations and frequencies under increasing stress.

  20. Electrical properties of breast cancer cells from impedance measurement of cell suspensions

    Science.gov (United States)

    Qiao, G.; Duan, W.; Chatwin, C.; Sinclair, A.; Wang, W.

    2010-04-01

    Impedance spectroscopy of biological cells has been used to monitor cell status, e.g. cell proliferation, viability, etc. It is also a fundamental method for the study of the electrical properties of cells which has been utilised for cell identification in investigations of cell behaviour in the presence of an applied electric field, e.g. electroporation. There are two standard methods for impedance measurement on cells. The use of microelectrodes for single cell impedance measurement is one method to realise the measurement, but the variations between individual cells introduce significant measurement errors. Another method to measure electrical properties is by the measurement of cell suspensions, i.e. a group of cells within a culture medium or buffer. This paper presents an investigation of the impedance of normal and cancerous breast cells in suspension using the Maxwell-Wagner mixture theory to analyse the results and extract the electrical parameters of a single cell. The results show that normal and different stages of cancer breast cells can be distinguished by the conductivity presented by each cell.

  1. Grain size-dependent magnetic and electric properties in nanosized YMnO3 multiferroic ceramics

    Directory of Open Access Journals (Sweden)

    Han Tai-Chun

    2011-01-01

    Full Text Available Abstract Magnetic and electric properties are investigated for the nanosized YMnO3 samples with different grain sizes (25 nm to 200 nm synthesized by a modified Pechini method. It shows that magnetic and electric properties are strongly dependent on the grain size. The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM transition temperature increases from 52 to 74 K. A corresponding shift of the dielectric anomaly is observed, indicating a strong correlation between the electric polarization and the magnetic ordering. Further analysis suggests that the rising of AFM transition temperature with increasing grain size should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters. Furthermore, among all samples, the sample with grain size of 95 nm is found to have the smallest leakage current density (< 1 μA/cm2. PACS: 75.50.Tt, 75.50.Ee, 75.85.+t, 77.84.-s

  2. Facile synthesis and electrical switching properties of V{sub 2}O{sub 3} powders

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Haining; Liu, Dongqing, E-mail: dongqingliu@ymail.com; Cheng, Haifeng; Yang, Lixiang; Zhang, Chaoyang; Zheng, Wenwei

    2017-03-15

    Highlights: • Single crystal uniform V{sub 2}O{sub 3} powders have been synthesized without additional surfactant. • Powders were obtained in only 6 h. • Powders exhibit reversible phase transition properties. • Powders have excellent electrical switching properties with resistance changes as large as 10{sup 4}. - Abstract: V{sub 2}O{sub 3} powders were synthesized with mercaptoacetic acid (C{sub 2}H{sub 4}O{sub 2}S) as reducing agent and stabilizer via a facile hydrothermal approach. The crystalline structure, surface morphology, valence state of the derived V{sub 2}O{sub 3} powders were characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy. It was found that the ratio and reaction time played a duel role in the formation and morphology of the V{sub 2}O{sub 3} powders. The metal-insulator transition properties of V{sub 2}O{sub 3} powders were studied by the differential scanning calorimetry curve and variable temperature Raman spectra. The change in electrical resistance due to the metal-insulator transition was measured from 80 to 240 K using physical property measurement system. The results showed V{sub 2}O{sub 3} samples had excellent electrical switching properties with resistance changes as large as 10{sup 4}. This simple and fast synthesis approach makes the V{sub 2}O{sub 3} powders easily accessible for exploring their fundamental properties and potential applications in novel electronic devices.

  3. Investigation of properties of surfaces, recovered by electric-arc coatings

    Directory of Open Access Journals (Sweden)

    Микола Федорович Дмитриченко

    2016-12-01

    Full Text Available Physical and mechanical properties of the recovered surfaces of the machine parts by electric-arc coating are considered from position of influence of technological parameters of coating process. Dependences of adhesion strength, porosity and gas permeability of coatings from the technological coating modes (current voltage of arc, spraying distance, pressure of the compressed air are set as a result of the conducted experiments

  4. Electrical properties and flux performance of composite ceramic hydrogen separation membranes

    DEFF Research Database (Denmark)

    Fish, J.S.; Ricote, Sandrine; O'Hayre, R.

    2015-01-01

    The electrical properties and hydrogen permeation flux behavior of the all-ceramic protonic/electronic conductor composite BaCe0.2Zr0.7Y0.1O3-δ/Sr0.95Ti0.9Nb0.1O3-δ (BCZY27/STN95: BS27) are evaluated. Conductivity and hydrogen permeability are examined as a function of phase volume ratios. Total...

  5. Hydrogen storing and electrical properties of hyperbranched polymers-based nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Rehim, Mona H., E-mail: monaabdelrehim@yahoo.com [Packing and Packaging Materials Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Cairo (Egypt); Ismail, Nahla; Badawy, Abd El-Rahman A.A. [Physical Chemistry Department, Center of Excellence for advanced Science, Renewable Energy Group, National Research Center, Cairo (Egypt); Turky, Gamal [Microwave Physics and Dielectrics Department, National Research Center, Cairo (Egypt)

    2011-09-15

    Highlights: {center_dot} The hydrogen storage capacity of hyperbranched P-Urea, PAMAM and PAMAM and VO{sub x} is studied and electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. {center_dot} Electrical properties measurements for the samples showed complete insulating behavior at hydrogenation measuring temperature. {center_dot} These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage. - Abstract: Hydrogen storage and electrical properties of different hyperbranched polymer systems beside a nanocomposite are studied. The polymers examined are aliphatic hyperbranched poly urea (P-Urea), polyamide amine (PAMAM) and polyamide amine/vanadium oxide (PAMAM/VO{sub x}) nanocomposite. At 80 K and up to 20 bar hydrogen pressure, the hydrogen storage capacity of hyperbranched P-Urea reached 1.6 wt%, 0.9 wt% in case of PAMAM and 0.6 wt% for VO{sub x}. The hydrogen storage capacity significantly enhanced when PAMAM and VO{sub x} form a nanocomposite and increased up to 2 wt%. At 298 K and up to 20 bar, all the samples did not show measurable hydrogen uptake. Electrical properties of the samples are also investigated; the measurements showed complete insulating behavior at hydrogenation measuring temperature. These investigations ensure that the polymer conductivity does not play a role in hydrogen uptake, also hyperbranched polymers are promising materials for hydrogen storage.

  6. Synthesis and electrical properties of PANI-CNT-CdS nanocomposites

    Science.gov (United States)

    Goswami, M.; Mukherjee, A.; Ghosh, R.; Meikap, A. K.

    2016-05-01

    Polyaniline-CNT-CdS nanocomposite has been synthesized by the chemical oxidative polymerization reaction. The particle size of nanocomposites lies in between 2.7 to 4.8 nm. I-V characteristics of the nanocomposite shows a non linear behaviour. The dc electrical transport property of Polyaniline-CNT-CdS nanocomposites has been investigated within a temperature range 77≤T≤300K. The dc conductivity follows 3D variable range hopping (VRH) model.

  7. Mechanical and Electrical Properties of Sulfur-Containing Polymeric Materials Prepared via Inverse Vulcanization

    OpenAIRE

    Sergej Diez; Alexander Hoefling; Patrick Theato; Werner Pauer

    2017-01-01

    Recently, new methods have been developed for the utilization of elemental sulfur as a feedstock for novel polymeric materials. One promising method is the inverse vulcanization, which is used to prepare polymeric structures derived from sulfur and divinyl comonomers. However, the mechanical and electrical properties of the products are virtually unexplored. Hence, in the present study, we synthesized a 200 g scale of amorphous, hydrophobic as well as translucent, hyperbranched polymeric sulf...

  8. influence of x—rays on some electrical properties of the bovine ...

    African Journals Online (AJOL)

    l In this study, the influence of x-rays on the ionic properties of the vitreous humour of the bovine. , eyes has been investigated. Each vitreous ... Measurements of ionic conductivity, pH and bulk electric l potential were made on the irradiated ... total of 26 calf eyes were irradiated with UV-A light for a period of 3 hours and the ...

  9. INTRINSIC ELECTRICAL PROPERTIES OF MAMMALIAN NEURONS AND CNS FUNCTION: A HISTORICAL PERSPECTIVE

    Directory of Open Access Journals (Sweden)

    Rodolfo R Llinas

    2014-11-01

    Full Text Available This brief review summarizes work done in mammalian neuroscience concerning the intrinsic electrophysiological properties of four neuronal types; Cerebellar Purkinje cells, inferior olivary cells, thalamic cells, and some cortical interneurons. It is a personal perspective addressing an interesting time in neuroscience when the reflex view of brain function, as the paradigm to understand global neuroscience, began to be modified towards one in which sensory input modulates rather than dictates brain function. The perspective of the paper is not a comprehensive description of the intrinsic electrical properties of all nerve cells but rather addresses a set of cell types that provide indicative examples of mechanisms that modulate brain function.

  10. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Raj, S. Gokul [Department of Physics, C. Kandaswami Naidu College For Men (CKNC), Annanagar, Chennai-600102 (India); Mathivanan, V.; Mohan, R. [Department of Physics, Presidency College, Chennai – 600005 (India); Kumar, G. Ramesh, E-mail: rameshvandhai@gmail.com; Yathavan, S. [Department of Physics, University College of Engineering Arni, Anna University Chennai, Arni-632317 (India)

    2016-05-06

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr{sub 0.6}B{sub 0.4}Nb{sub 2}O{sub 6}) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce{sup +} ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  11. Microwave-assisted synthesis and magneto-electrical properties of Mg-Zn ferrimagnetic oxide nanostructures

    Science.gov (United States)

    Gore, Shyam K.; Tumberphale, U. B.; Jadhav, Santosh S.; Kawale, R. S.; Naushad, Mu.; Mane, Rajaram S.

    2018-02-01

    The structural, magnetic and dielectric properties of Mg-Zn mixed ferrimagnetic oxides are studied and reported with an aim to know the role of non-magnetic Zn2+ in modification of the properties. Ferrites with the general formula Mg1-xZnxFe2O4 (MZF) where 'x' varies from 0.0 to 0.5 were synthesized by microwave assisted sol-gel combustion method. Effects on the magnetic and electrical properties caused by changes in surface morphology, grain size, grain boundary, and micro-strain on account of Zn2+-substitution have been explored in-depth. These effects reveal considerable variations in coercive force, saturation magnetization and residual magnetization values obtained from hysteresis curves of MgFe2O4 on Zn2+ substitution. The effects of temperature and frequency on dielectric properties are investigated and reported.

  12. Microscopic study of electrical properties of CrSi2 nanocrystals in silicon

    Science.gov (United States)

    Dózsa, László; Lányi, Štefan; Raineri, Vito; Giannazzo, Filippo; Galkin, Gennadevich Nikolay

    2011-12-01

    Semiconducting CrSi2 nanocrystallites (NCs) were grown by reactive deposition epitaxy of Cr onto n -type silicon and covered with a 50-nm epitaxial silicon cap. Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface. The electrical characteristics were investigated in Schottky junctions by current-voltage and capacitance-voltage measurements. Atomic force microscopy (AFM), conductive AFM and scanning probe capacitance microscopy (SCM) were applied to reveal morphology and local electrical properties. The scanning probe methods yielded specific information, and tapping-mode AFM has shown up to 13-nm-high large-area protrusions not seen in the contact-mode AFM. The electrical interaction of the vibrating scanning tip results in virtual deformation of the surface. SCM has revealed NCs deep below the surface not seen by AFM. The electrically active probe yielded significantly better spatial resolution than AFM. The conductive AFM measurements have shown that the Cr-related point defects near the surface are responsible for the leakage of the macroscopic Schottky junctions, and also that NCs near the surface are sensitive to the mechanical and electrical stress induced by the scanning probe.

  13. Microscopic study of electrical properties of CrSi2 nanocrystals in silicon

    Directory of Open Access Journals (Sweden)

    Lányi Štefan

    2011-01-01

    Full Text Available Abstract Semiconducting CrSi2 nanocrystallites (NCs were grown by reactive deposition epitaxy of Cr onto n-type silicon and covered with a 50-nm epitaxial silicon cap. Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface. The electrical characteristics were investigated in Schottky junctions by current-voltage and capacitance-voltage measurements. Atomic force microscopy (AFM, conductive AFM and scanning probe capacitance microscopy (SCM were applied to reveal morphology and local electrical properties. The scanning probe methods yielded specific information, and tapping-mode AFM has shown up to 13-nm-high large-area protrusions not seen in the contact-mode AFM. The electrical interaction of the vibrating scanning tip results in virtual deformation of the surface. SCM has revealed NCs deep below the surface not seen by AFM. The electrically active probe yielded significantly better spatial resolution than AFM. The conductive AFM measurements have shown that the Cr-related point defects near the surface are responsible for the leakage of the macroscopic Schottky junctions, and also that NCs near the surface are sensitive to the mechanical and electrical stress induced by the scanning probe.

  14. Integrated petrophysics and rock physics modeling for well log interpretation of elastic, electrical, and petrophysical properties

    Science.gov (United States)

    Wu, Wenting; Grana, Dario

    2017-11-01

    Rock and fluid volumetric properties, such as porosity, saturation, and mineral volumes, are generally estimated from petrophysical measurements such as density, resistivity, neutron porosity and gamma ray, through petrophysical equations. The computed petrophysical properties and sonic log measurements are generally used to estimate the petro-elastic relationship between elastic and rock and fluid volumetric properties used in reservoir characterization. In this paper, we present a unified workflow that includes petrophysical relations and rock physics models for the estimation of rock and fluid properties from elastic, electrical, and petrophysical (porosity, density, and lithology) measurements. The multi-physics model we propose has the advantage of accounting for the coupled effect of rock and fluid properties in the joint petro-elastic and electrical domains, and potentially reduce the uncertainty in the well log interpretation. Furthermore, the presented workflow can be eventually extended to three-dimensional reservoir characterization problems, where seismic and electromagnetic data are available. To demonstrate the validity of the methodology, we show the application of this multi-physics model to both laboratory measurements and well log data.

  15. Tensile and electrical properties of high-strength high-conductivity copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Eatherly, W.S. [Oak Ridge National Lab., TN (United States)

    1998-09-01

    Electrical conductivity and tensile properties have been measured on an extruded and annealed CuCrNb dispersion strengthened copper alloy which has been developed for demanding aerospace high heat flux applications. The properties of this alloy are somewhat inferior to GlidCop dispersion strengthened copper and prime-aged CuCrZr over the temperature range of 20--500 C. However, if the property degradation in CuCrZr due to joining operations and the anisotropic properties of GlidCop in the short transverse direction are taken into consideration, CuCrNb may be a suitable alternative material for high heat flux structural applications in fusion energy devices. The electrical conductivity and tensile properties of CuCrZr that was solution annealed and then simultaneously aged and diffusion bonded are also summarized. A severe reduction in tensile elongation is observed in the diffusion bonded joint, particularly if a thin copper shim is not placed in the diffusion bondline.

  16. Material properties of the F82H melted in an electric arc furnace

    Energy Technology Data Exchange (ETDEWEB)

    Sakasegawa, Hideo, E-mail: sakasegawa.hideo@jaea.go.jp [Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Tanigawa, Hiroyasu [Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Kano, Sho; Abe, Hiroaki [Institute for Materials Research, Tohoku university, Sendai, Miyagi (Japan)

    2015-10-15

    Highlights: • We studied material properties of reduced activation ferritic/martensitic steel. • We melted F82H using a 20 tons electric arc furnace for the first time. • Mass effect likely affected material properties. • MX (M: Metal, C: Carbon and/or Nitrogen) precipitates mainly formed on grain and sub grain boundaries. - Abstract: Fusion DEMO reactor requires over 11,000 tons of reduced activation ferritic/martensitic steel. It is necessary to develop the manufacturing technology for fabricating such large-scale steel with appropriate mechanical properties. In this work, we focused fundamental mechanical properties and microstructures of F82H-BA12 heat which was melted using a 20 tons electric arc furnace followed by electroslag remelting process. Its raw material of iron was blast furnace iron, because the production volume of electrolytic iron which has been used in former heats, is limited. After melting and forging, this F82H-BA12 heat was heat-treated in four different conditions to consider their fluctuations and to optimize them, and tensile and Charpy impact tests were then performed. The result of these mechanical properties were comparable to those of former F82H heats less than 5 tons which were melted applying vacuum induction melting.

  17. Effect of pulsed electric field on the rheological and colour properties of soy milk.

    Science.gov (United States)

    Xiang, Bob Y; Simpson, Marian V; Ngadi, Michael O; Simpson, Benjamin K

    2011-12-01

    The effects of pulsed electric field (PEF) treatments on rheological and colour properties of soy milk were evaluated. Flow behaviour, viscosity and rheological parameters of PEF-treated soy milk were monitored using a controlled stress rheometer. For PEF treatments, electric field intensity of 18, 20 and 22 kV cm(-1) and number of pulses of 25, 50, 75 and 100 were used. For the measurements of rheological properties of soy milk shear rates between 0 and 200 s(-1) was used. The rheological behaviour of control and the PEF-treated soy milk were described using a power law model. The PEF treatments affected the rheological properties of soy milk. Apparent viscosity of soy milk increased from 6.62 to 7.46 (10(-3) Pa s) with increase in electric field intensity from 18 to 22 kV cm(-1) and increase in the number of pulses from 0 to 100. The consistency index (K) of soy milk also changed with PEF treatments. Lightness (L*), red/greenness (a*) and yellowness/blueness (b*) of soy milk were affected by PEF treatments.

  18. Effect of γ-irradiation on the optical and electrical properties of fiber reinforced composites

    Science.gov (United States)

    Anwar, Ahmad; Elfiky, Dalia; Ramadan, Ahmed M.; Hassan, G. M.

    2017-05-01

    The effect of gamma irradiation on the optical and electrical properties of the reinforced fiber polymeric based materials became an important issue. Fiberglass/epoxy and Kevlar fiber/epoxy were selected as investigated samples manufactured with hand lay-up without autoclave curing technique. The selected technique is simple and low cost while being rarely used in space materials production. The electric conductivity and dielectric constant for those samples were measured with increasing the gamma radiation dose. Moreover, the absorptivity, band gap and color change were determined. Fourier transform infrared (FTIR) was performed to each of the material's constituent to evaluate the change in the investigated materials due to radiation exposure dose. In this study, the change of electrical properties for both investigated materials showed a slight variation of the test parameters with respect to the gamma dose increase; this variation is placed in the insulators rang. The tested samples showed an insulator stable behavior during the test period. The change of optical properties for both composite specimens showed the maximum absorptivity at the gamma dose 750 kGy. These materials are suitable for structure materials and thermal control for orbital life less than 7 years. In addition, the transparency of epoxy matrix was degraded. However, there is no color change for either Kevlar fiber or fiberglass.

  19. Magnetoresistance and electrical properties of multi-component copper chalcogenides at pressures up to 50 GPa

    Science.gov (United States)

    Melnikova, Nina; Tebenkov, Alexander; Babushkin, Alexey; Kurochka, Kirill; Phase Transitions Team; Transport Properties Team; Novel Materials Team

    2013-06-01

    Multi-component chalcogenides based on layered semiconductors A3B6 (such as InS, InSe, GaS, GaSe, etc) are new objects of study, they have interesting physical properties and undergo temperature and baric phase transitions. This paper presents the results of a study of the electrical properties and magnetoresistance of CuInS2, CuInSe2, CuInAsS3, CuInAsSe3, CuInSbS3 at pressures up to 50 GPa. High pressures have been generated in the cell with synthetic carbonado-type diamond anvils that can be used as electric contacts. Electric properties at high pressure have been investigated on dc current and by means of impedance spectroscopy. Magnetoresistance has been measured in transverse magnetic field. The pressure ranges of noticeable changes in a behavior of magnetoresistance, of impedance and admittance, tangent of loss angle, relaxation time upon a pressure increase and a pressure decrease are established. This behavior of physical parameters can be due to structural transitions and due to a change of electron structure. This work was supported in part by the Russian Foundation for Basic Research, project no. 13-02-00633.

  20. Dielectric and insulating properties of an acrylic DEA material at high near-DC electric fields

    Science.gov (United States)

    Di Lillo, L.; Schmidt, A.; Bergamini, A.; Ermanni, P.; Mazza, E.

    2011-04-01

    A number of adaptive structure applications call for the generation of intense electric fields (in excess of 70 MV/m). Such intense fields across the thickness of a thin polymer dielectric layer are typically used to exploit the direct electromechanical coupling in the form of a Maxwell stress: (see manuscript) Where V/d is the applied field, ɛ0 is the permittivity of vacuum and ɛ is the relative permittivity of the material. The field that can be applied to the dielectric is limited by the dielectric strength of the material. Below the limit set by the breakdown, the material is generally assumed to have a field independent dielectric constant and to be a perfect insulator, i.e. to have an infinite volume resistivity. While extensive investigations about the mechanical properties of the materials used for electronic Dielectric Elastomer Actuators (DEA) are available from literature, the results of the investigation of the insulating and dielectric properties of these materials, especially under conditions (electric field and frequency) similar to the ones encountered during operation are not available. In the present contribution, we present a method and a set-up for the measurement of the electric properties of thin polymer films, such as the ones used for the fabrication of electronic DEAs, under conditions close to operations. The method and setup where developed to investigate the properties of 'stiff' thin polymer films, such as Polyimide or Polyvinylidenefluoride, used for Electro-Bonded Laminates (EBLs). The properties of the well known VHB 4910 acrylic elastomer are presented to illustrate how the permittivity and the leakage current can be measured as a function of the electric field and the deformation state, using the proposed set-up. The material properties were measured on membranes under different fixed pre-stretch conditions (λ 1, λ2=3, 4, 5), in order to eliminate effects due to the change in sample geometry, using gold sputtered electrodes, 20

  1. PENUMBUHAN LAPISAN TIPIS SILIKON MIKROKRISTAL TERHIDROGENASI DENGAN TEKNIK HWC-VHF-PECVD

    Directory of Open Access Journals (Sweden)

    Ida Usman

    2012-02-01

    Full Text Available Telah dikembangkan teknik HWC-VHF-PECVD (Hot Wire Cell Very High Frequency Plasma Enhanced Chemical Vapor Deposition untuk menumbuhkan lapisan tipis silikon mikrokristal terhidrogenasi (mc-Si:H. Dari hasil penumbuhan lapisan tipis yang dilakukan, teknik HWC-VHF-PECVD memperlihatkan laju deposisi yang lebih tinggi dibandingkan laju deposisi lapisan tipis yang diperoleh dari teknik PECVD maupun teknik VHF-PECVD konvensional. Berdasarkan hasil pengukuran XRD dan SEM, lapisan yang diperoleh pada temperatur filamen yang rendah masih berstruktur amorf. Indikasi yang mengarah pada pembentukan lapisan tipis berstruktur mikrokristalin mulai terlihat pada temperatur filamen ≥ 500oC, dimana puncak-puncak di fraksi spektrum XRD untuk orientasi kristalin tertentu mulai terbentu, sejalan dengan pembentukan butiran-butiran kristalin dari hasil foto SEM permukaan lapisan-lapisan tersebut.

  2. Making better scar: Emerging approaches for modifying mechanical and electrical properties following infarction and ablation.

    Science.gov (United States)

    Holmes, Jeffrey W; Laksman, Zachary; Gepstein, Lior

    2016-01-01

    Following myocardial infarction (MI), damaged myocytes are replaced by collagenous scar tissue, which serves an important mechanical function - maintaining integrity of the heart wall against enormous mechanical forces - but also disrupts electrical function as structural and electrical remodeling in the infarct and borderzone predispose to re-entry and ventricular tachycardia. Novel emerging regenerative approaches aim to replace this scar tissue with viable myocytes. Yet an alternative strategy of therapeutically modifying selected scar properties may also prove important, and in some cases may offer similar benefits with lower risk or regulatory complexity. Here, we review potential goals for such modifications as well as recent proof-of-concept studies employing specific modifications, including gene therapy to locally increase conduction velocity or prolong the refractory period in and around the infarct scar, and modification of scar anisotropy to improve regional mechanics and pump function. Another advantage of scar modification techniques is that they have applications well beyond MI. In particular, ablation treats electrical abnormalities of the heart by intentionally generating scar to block aberrant conduction pathways. Yet in diseases such as atrial fibrillation (AF) where ablation can be extensive, treating the electrical disorder can significantly impair mechanical function. Creating smaller, denser scars that more effectively block conduction, and choosing the location of those lesions by balancing their electrical and mechanical impacts, could significantly improve outcomes for AF patients. We review some recent advances in this area, including the use of computational models to predict the mechanical effects of specific lesion sets and gene therapy for functional ablation. Overall, emerging techniques for modifying scar properties represents a potentially important set of tools for improving patient outcomes across a range of heart diseases

  3. Improved electrical properties of cadmium substituted cobalt ferrites nano-particles for microwave application

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Rabia [Institute of Chemical Sciences, Gomal University, D. I. Khan (Pakistan); Hussain Gul, Iftikhar, E-mail: iftikhar.gul@scme.nust.edu.pk [Thermal Transport Laboratory (TTL), Materials Engineering Department, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology - NUST, H-12 Campus, Islamabad (Pakistan); Zarrar, Muhammad [Thermal Transport Laboratory (TTL), Materials Engineering Department, School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology - NUST, H-12 Campus, Islamabad (Pakistan); Anwar, Humaira [Islamabad Model College for Girls G-10/2, Islamabad (Pakistan); Khan Niazi, Muhammad Bilal [Department of Chemicals Engineering, SCME, NUST, H-12 Campus, Islamabad (Pakistan); Khan, Azim [Institute of Chemical Sciences, Gomal University, D. I. Khan (Pakistan)

    2016-05-01

    Cadmium substituted cobalt ferrites with formula Cd{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4} (x=0.0, 0.2, 0.35, 0.5), have been synthesized by wet chemical co-precipitation technique. Electrical, morphological and Structural properties of the samples have been studied using DC electrical resistivity and Impedance analyzer, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), respectively. XRD, SEM and AFM have been used to study the structural parameters such as measured density, lattice constant, X-ray density, crystallite size and morphology of the synthesized nano-particles. Debye–Scherrer formula has been used for the estimation of crystallite sizes. The estimated crystallite sizes were to be 15–19±2 nm. Hopping length of octahedral and tetrahedral sites have been calculated using indexed XRD data. The porosity and lattice constant increased as Cd{sup 2+}concentration increases. DC electrical resistivity was performed using two probe technique. The decrease of resistivity with temperature confirms the semiconducting nature of the samples. The dielectric properties variation has been studied at room temperature as a function of frequency. Variation of dielectric properties from 100 Hz to 5 MHz has been explained on the basis of Maxwell and Wagner’s model and hoping of electrons on octahedral sites. To separates the grains boundary and grains of the system Cd{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4} the impedance analysis were performed. - Highlights: • Preparation of homogeneous, spherical and single phase well crystallized cobalt ferrites. • A simple and economical PEG assisted wet chemical co-precipitation method has been used. • Increased in DC electrical resistivity and activation energy. • Decease in dielectric constant used for microwave absorber. • AC conductivity of Cd{sup 2+} substituted Co-ferrites increases.

  4. Electrical properties and sensing ability of novel piezoelectric ceramic fibers with Pt core

    Science.gov (United States)

    Du, Jianzhou; Qiu, Jinhao; Zhu, Kongjun; Ji, Hongli; Zhao, Huayun

    2012-04-01

    The traditional sintering method was used to sinter the pure and Fe2O3 doped 0.55Pb(Ni0.33Nb0.67)O3-0.45Pb(Zr0.3Ti0.7)O3 (abbreviate as PNN-PZT and PFNN-PZT, respectively) ceramics. The addition of Fe2O3 significantly improved the microstructure and electrical properties. Compared with pure PNN-PZT ceramics, higher dielectric and piezoelectric properties of d31~-390 pC/N, ɛ r ~6298 were obtained for the PFNN-PZT sample sintered at 1175°C for 2 h. Hence, the PFNN-PZT ceramics sample was selected to fabricate piezoelectric ceramic fibers with Pt core (PFC). Both the green fibers and bulk ceramics were sintered at 1150-1225°C for 2 h in a closed crucible, respectively. The effect of sintering temperature on the microstructure and electrical properties of the PFNN-PZT fibers was investigated. The optimal piezoelectric properties are obtained for the sample sintered at 1175°C for 2 h. The relative dielectric constant and piezoelectric constant show peak values of ɛ r~3683, d31~-197.4 pC/N, respectively. The PFC is a new type piezoelectric device, which can be used for sensors or actuators. The results of sensing experiment show that the piezoelectric ceramic fiber with Pt core has high sensitivity for the Lamb waves.

  5. Unconventional symmetries of Fermi liquid and Cooper pairing properties with electric and magnetic dipolar fermions.

    Science.gov (United States)

    Li, Yi; Wu, Congjun

    2014-12-10

    The rapid experimental progress of ultra-cold dipolar fermions opens up a whole new opportunity to investigate novel many-body physics of fermions. In this article, we review theoretical studies of the Fermi liquid theory and Cooper pairing instabilities of both electric and magnetic dipolar fermionic systems from the perspective of unconventional symmetries. When the electric dipole moments are aligned by the external electric field, their interactions exhibit the explicit d(r(2)-3z(2)) anisotropy. The Fermi liquid properties, including the single-particle spectra, thermodynamic susceptibilities and collective excitations, are all affected by this anisotropy. The electric dipolar interaction provides a mechanism for the unconventional spin triplet Cooper pairing, which is different from the usual spin-fluctuation mechanism in solids and the superfluid (3)He. Furthermore, the competition between pairing instabilities in the singlet and triplet channels gives rise to a novel time-reversal symmetry breaking superfluid state. Unlike electric dipole moments which are induced by electric fields and unquantized, magnetic dipole moments are intrinsic proportional to the hyperfine-spin operators with a Lande factor. Its effects even manifest in unpolarized systems exhibiting an isotropic but spin-orbit coupled nature. The resultant spin-orbit coupled Fermi liquid theory supports a collective sound mode exhibiting a topologically non-trivial spin distribution over the Fermi surface. It also leads to a novel p-wave spin triplet Cooper pairing state whose spin and orbital angular momentum are entangled to the total angular momentum J = 1 dubbed the J-triplet pairing. This J-triplet pairing phase is different from both the spin-orbit coupled (3)He-B phase with J = 0 and the spin-orbit decoupled (3)He-A phase.

  6. Mechanical, Thermal, and Electrical Properties of Graphene-Epoxy Nanocomposites—A Review

    Directory of Open Access Journals (Sweden)

    Rasheed Atif

    2016-08-01

    Full Text Available Monolithic epoxy, because of its brittleness, cannot prevent crack propagation and is vulnerable to fracture. However, it is well established that when reinforced—especially by nano-fillers, such as metallic oxides, clays, carbon nanotubes, and other carbonaceous materials—its ability to withstand crack propagation is propitiously improved. Among various nano-fillers, graphene has recently been employed as reinforcement in epoxy to enhance the fracture related properties of the produced epoxy–graphene nanocomposites. In this review, mechanical, thermal, and electrical properties of graphene reinforced epoxy nanocomposites will be correlated with the topographical features, morphology, weight fraction, dispersion state, and surface functionalization of graphene. The factors in which contrasting results were reported in the literature are highlighted, such as the influence of graphene on the mechanical properties of epoxy nanocomposites. Furthermore, the challenges to achieving the desired performance of polymer nanocomposites are also suggested throughout the article.

  7. Electrical properties of alkali-activated slag composite with combined graphite/CNT filler

    Science.gov (United States)

    Rovnaník, P.; Míková, M.; Kusák, I.

    2017-10-01

    Alkali-activated industrial by-products such as blast furnace slag are known to possess properties which are comparable to or even better than those observed for ordinary Portland cement. The combination of alkali-activated slag matrix with conductive filler introduces new functionalities which are commonly known for self-sensing or self-heating concrete. The present paper discusses the effect of the mixture of two different conductive fillers, graphite powder and carbon nanotubes (CNTs), on the electrical properties of alkali-activated slag mortars. Prepared samples were also tested for their mechanical properties and microstructure was investigated by means of mercury intrusion porosimetry and scanning electron microscopy. The percolation threshold for the resistance was reached for the mixture containing 0.1% CNTs and 8% graphite powder.

  8. Thermo-electrical properties of composite semiconductor thin films composed of nanocrystalline graphene-vanadium oxides.

    Science.gov (United States)

    Jung, Hye-Mi; Um, Sukkee

    2014-12-01

    This paper presents an experimental comparative study involving the characterization of the thermo-electrical and structural properties of graphene-based vanadium oxide (graphene-VOx) composite thin films on insulating and conducting surfaces (i.e., fused quartz and acrylic resin-impregnated graphite) produced by a sol-gel process via dipping-pyrolysis. A combination of FE-SEM and XPS analyses revealed that the graphene-VOx composite thin films (coated onto fused quartz) exhibiting the microstructure of 2-graded nanowire arrays with a diameter of 40-80 nm were composed of graphene, a few residual oxygen-containing functional groups (i.e., C-O and C=O), and the VO2 Magnéli phase. The temperature-dependent electrical resistance measured on the as-deposited thin films clearly demonstrated that the graphene-VOx composite nanowire arrays thermally grown on fused quartz act as a semiconductor switch, with a transition temperature of 64.7 degrees C in the temperature range of -20 degrees C to 140 degrees C, resulting from the contributions of graphene and graphene oxides. In contrast, the graphene-VOx composite thin films deposited onto acrylic resin-impregnated graphite exhibit a superlinear semiconducting property of extremely low electrical resistance with negative temperature coefficients (i.e., approximately four orders of magnitude lower than that of the fused quartz), despite the similar microstructural and morphological characteristics. This difference is attributed to the synergistic effects of the paramagnetic metal feature of the tightly stacked nanowire arrays consisting of hexagonal V2O3 on the intrinsic electrical properties of the acrylic resin-impregnated graphite substrate, as revealed by FE-SEM, EDX, AFM, and XRD measurements. Although the thermo-sensitive electrical properties of the graphene-VOx composite thin films are very substrate specific, the applicability of graphene sheets can be considerably effective in the formation of highly planar arrays

  9. Edge magnetism impact on electrical conductance and thermoelectric properties of graphenelike nanoribbons

    Science.gov (United States)

    Krompiewski, Stefan; Cuniberti, Gianaurelio

    2017-10-01

    Edge states in narrow quasi-two-dimensional nanostructures determine, to a large extent, their electric, thermoelectric, and magnetic properties. Nonmagnetic edge states may quite often lead to topological-insulator-type behavior. However, another scenario develops when the zigzag edges are magnetic and the time reversal symmetry is broken. In this work we report on the electronic band structure modifications, electrical conductance, and thermoelectric properties of narrow zigzag nanoribbons with spontaneously magnetized edges. Theoretical studies based on the Kane-Mele-Hubbard tight-binding model show that for silicene, germanene, and stanene both the Seebeck coefficient and the thermoelectric power factor are strongly enhanced for energies close to the charge neutrality point. A perpendicular gate voltage lifts the spin degeneracy of energy bands in the ground state with antiparallel magnetized zigzag edges and makes the electrical conductance significantly spin polarized. Simultaneously the gate voltage worsens the thermoelectric performance. Estimated room-temperature figures of merit for the aforementioned nanoribbons can exceed a value of 3 if phonon thermal conductances are adequately reduced.

  10. Study on Electrical Properties of PALF Reinforced Bisphenol-A Composite

    Directory of Open Access Journals (Sweden)

    Vinod B.

    2018-01-01

    Full Text Available These days, composite materials successfully substitute the traditional materials due to its various significant applications. This paper examines the influence of fiber orientation and fiber length on electrical properties of PALF reinforced Bisphenol-A composite and explores the potential of using PALF as reinforcing material for electrical applications such as terminals, connectors, motor body cover, industrial and household plugs and circuit boards. The resistance and inductance of resin material is increased by 24.19% and 24.13% respectively after reinforcement of PALF in different orientations and its value increased by 37.93% and 37.81% respectively after reinforcement of PALF in different lengths. Similarly, Capacitance and Dielectric constant of resin material decreased by 19.44% and 19.39% respectively after reinforcement of PALF in different orientations and its value decreased by 27.67% and 27.50% respectively after reinforcement of PALF in different lengths. It can be inferred from this study that the fiber orientations and fiber lengths greatly effects the electrical properties of PALF composite.

  11. Heteroepitaxial growth and electric properties of (110)-oriented scandium nitride films

    Science.gov (United States)

    Ohgaki, Takeshi; Sakaguchi, Isao; Ohashi, Naoki; Haneda, Hajime

    2017-10-01

    ScN films were grown on MgO(110) substrates and α-Al2O3(10 1 bar 0) substrates by a molecular beam epitaxy method, and their crystalline orientation, crystallinity, and electric properties were examined. (110)-oriented ScN films were epitaxially grown on MgO(110) substrates with the same crystal orientations, and ScN films with an orientation relationship (110)ScN || (10 1 bar 0)α-Al2O3 and [001]ScN || [ 1 2 bar 10 ]α-Al2O3 were epitaxially grown on α-Al2O3(10 1 bar 0) substrates. Remarkably, electric-resistivity anisotropy was observed for ScN films grown on MgO(110) substrates, and the anisotropy depended on the growth temperature. The carrier concentration and Hall mobility of the ScN films grown on α-Al2O3(10 1 bar 0) substrates ranged from 1019-1021 cm-3 and 10-150 cm2 V-1 s-1, respectively. The crystallinity, crystalline-orientation anisotropy, and electric properties of the films were strongly affected by growth conditions. For the growth of ScN films with high mobility on α-Al2O3(10 1 bar 0) substrates, a high temperature and an appropriate ratio of source materials were necessary.

  12. Antimony doped cadmium selenium nanobelts with enhanced electrical and optoelectrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lijie [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Yu, Hongfei; Cao, Wei; Dong, Youqing; Zou, Chao; Yang, Yun [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Huang, Shaoming, E-mail: smhuang@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Dai, Ning [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Zhu, Da-Ming, E-mail: ZhuD@umkc.edu [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); University of Missouri-Kansas City, Kansas City, MO 64110 (United States)

    2014-07-01

    Intrinsic and Sb-doped CdSe nanobelts (NBs) were synthesized via a thermal evaporation technique. The electrical transport properties of field effect transistors (FETs) fabricated using the NBs were investigated. The results indicate that the Sb-doped NBs behave as n-type semiconductors with improved electrical conductivity (10⁻¹ to 100 S/cm) compared with the intrinsic CdSe. Photodetectors made of single NB were also fabricated and investigated. The results show that Sb-doped NB photodetectors exhibit much higher responsivity (1.5 × 10⁴ A/W) and external quantum efficiency (1.2 × 10⁵) but lower on/off current ratio (~253) and longer response time (≤40 ms). Furthermore, both electrical transport and optoelectrical properties of the as-synthesized CdSe NBs can be tuned by changing the doping concentration. The results indicate that the as-synthesized NBs are excellent building blocks for constructing electronic and optoelectronic devices.

  13. Tailoring the thermal and electrical transport properties of graphene films by grain size engineering

    Science.gov (United States)

    Ma, Teng; Liu, Zhibo; Wen, Jinxiu; Gao, Yang; Ren, Xibiao; Chen, Huanjun; Jin, Chuanhong; Ma, Xiu-Liang; Xu, Ningsheng; Cheng, Hui-Ming; Ren, Wencai

    2017-02-01

    Understanding the influence of grain boundaries (GBs) on the electrical and thermal transport properties of graphene films is essentially important for electronic, optoelectronic and thermoelectric applications. Here we report a segregation-adsorption chemical vapour deposition method to grow well-stitched high-quality monolayer graphene films with a tunable uniform grain size from ~200 nm to ~1 μm, by using a Pt substrate with medium carbon solubility, which enables the determination of the scaling laws of thermal and electrical conductivities as a function of grain size. We found that the thermal conductivity of graphene films dramatically decreases with decreasing grain size by a small thermal boundary conductance of ~3.8 × 109 W m-2 K-1, while the electrical conductivity slowly decreases with an extraordinarily small GB transport gap of ~0.01 eV and resistivity of ~0.3 kΩ μm. Moreover, the changes in both the thermal and electrical conductivities with grain size change are greater than those of typical semiconducting thermoelectric materials.

  14. Effect of Electric Discharge on Properties of Nano-Particulate Catalyst for Plasma-Catalysis.

    Science.gov (United States)

    Lee, Chung Jun; Kim, Jip; Kim, Taegyu

    2016-02-01

    Heterogeneous catalytic processes have been used to produce hydrogen from hydrocarbons. However, high reforming temperature caused serious catalyst deteriorations and low energy efficiency. Recently, a plasma-catalyst hybrid process was used to reduce the reforming temperature and to improve the stability and durability of reforming catalysts. Effect of electric discharges on properties of nanoparticulate catalysts for plasma-catalysis was investigated in the present study. Catalyst-bed porosity was varied by packing catalyst beads with the different size in a reactor. Discharge power and onset voltage of the plasma were measured as the catalyst-bed porosity was varied. The effect of discharge voltage, frequency and voltage waveforms such as the sine, pulse and square was investigated. We found that the optimal porosity of the catalyst-bed exists to maximize the electric discharge. At a low porosity, the electric discharge was unstable to be sustained because the space between catalysts got narrow nearly close to the sheath region. On the other hand, at a high porosity, the electric discharge became weak because the plasma was not sufficient to interact with the surface of catalysts. The discharge power increased as the discharge voltage and frequency increased. The square waveform was more efficient than the sine and pulse one. At a high porosity, however, the effect of the voltage waveform was not considerable because the space between catalysts was too large for plasma to interact with the surface of catalysts.

  15. Electrical percolation, morphological and dispersion properties of MWCNT/PMMA nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Paulo Henrique da Silva Leite; Marchesin, Marcel Silva; Morales, Ana Rita; Bartoli, Julio Roberto, E-mail: piyke.coelho@gmail.com [Universidade de Campinas (UNICAMP), SP (Brazil). Escola de Engenharia Quimica

    2014-08-15

    Nanocomposites of poly (methyl methacrylate) (PMMA) and carbon nanotubes have a high potential for applications where conductivity and low specific weight are required. This piece of work concerns investigations of the level of dispersion and morphology on the electrical properties of in situ polymerized nanocomposites in different concentrations of multi-walled carbon nanotubes (MWCNT) in a PMMA matrix. The electrical conductivity was measured by the four point probe. The morphology and dispersion was analyzed by Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). The correlation between electrical conductivity and the MWCNT amount, presented a typical percolation behavior, whose electrical percolation threshold determined by power law relationship was 0.2 vol. (%) The exponent t from the percolation power law indicated the formation of a 3D network of randomly arranged MWCNT. SAXS detected that the structures are intermediate to disks or spheres indicating fractal geometry for the MWCNT aggregates instead of isolated rods. HR-TEM images allowed us to observe the MWCNT individually dispersed into the matrix, revealing their distribution without preferential space orientation and absence of significant damage to the walls. The combined results of SAXS and HR-TEM suggest that MWCNT into the polymeric matrix might present interconnected aggregates and some dispersed single structures. (author)

  16. Electrical and thermoelectric properties of different compositions of Ge–Se–In thin films

    Energy Technology Data Exchange (ETDEWEB)

    Aly, K.A., E-mail: kamalaly2001@gmail.com [Physics Department, Faculty of Science and Arts Khulais, University of Jeddah (Saudi Arabia); Physics Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut (Egypt); Dahshan, A., E-mail: adahshan73@gmail.com [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt); Department of Physics, Faculty of Science for Girls, King Khalid University, Abha (Saudi Arabia); Abbady, Gh. [Department of Physics, Faculty of Science, Assuit University, Assuit (Egypt); Saddeek, Y. [Physics Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut (Egypt)

    2016-09-15

    The effect of temperature in the range of 300–450 K and the indium content on the electrical and thermoelectric properties of Ge{sub 20}Se{sub 80−x}In{sub x} (0.0≤x≤24 at%) chalcogenide glassy thin films have been studied. From dc electrical and thermoelectric measurements, it was observed that the activation energies for electrical conductivity (ΔE) and for thermoelectric (ΔE{sub s}) decrease while the conductivity (σ) and Seebeck coefficient (S) increase upon introducing In into the Ge–Se glasses. In contrast to the behavior obtained with Bi or Pb doping, In incorporated in Ge–Se does not lead to a p-to n-type conduction inversion. The power factor (P) which is strongly depends on both of the Seebeck coefficient and the electrical conductivity. According to the obtained results, the Ge{sub 20}Se{sub 80−x}In{sub x} films can be considered potential candidates for incurring high action thermoelectric materials.

  17. Structural, mechanical and electrical properties of alloys in ternary Ag-Bi-Zn system

    Directory of Open Access Journals (Sweden)

    Minic, Duško M.

    2015-06-01

    Full Text Available Structural, mechanical and electrical properties of selected alloys in ternary Ag-Bi-Zn system are presented in this paper. Chosen alloys were investigated using X-Ray Diffraction (XRD, light optical microscopy, Scanning Electron Microscopy combined with Energy Dispersive Spectrometry (SEM-EDS, as well as by electrical conductivity and Brinell hardness measurements. Isolines of electrical conductivity and hardness for the entire Ag-Bi-Zn system were calculated using regression models.Este trabajo estudia las propiedades estructurales, mecánicas y eléctricas de aleaciones seleccionadas del sistema ternario Ag-Bi-Zn. Las aleaciones elegidas se han caracterizado por medio de difracción de rayos X, microscopía óptica, microscopía electrónica de barrido combinada con espectrometría de dispersión de energía, así como por medio de medidas de conductividad eléctrica y dureza Brinell. Por medio de modelos de regresión se han calculado las líneas de isoconductividad eléctrica y dureza para todo el sistema Ag-Bi-Zn.

  18. Characterization of the Hole Transport and Electrical Properties in the Small-Molecule Organic Semiconductors

    Science.gov (United States)

    Wang, L. G.; Zhu, J. J.; Liu, X. L.; Cheng, L. F.

    2017-10-01

    In this paper, we investigate the hole transport and electrical properties in a small-molecule organic material N, N'-bis(1-naphthyl)- N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB), which is frequently used in organic light-emitting diodes. It is shown that the thickness-dependent current density versus voltage ( J- V) characteristics of sandwich-type NPB-based hole-only devices cannot be described well using the conventional mobility model without carrier density or electric field dependence. However, a consistent and excellent description of the thickness-dependent and temperature-dependent J- V characteristics of NPB hole-only devices can be obtained with a single set of parameters by using our recently introduced improved model that take into account the temperature, carrier density, and electric field dependence of the mobility. For the small-molecule organic semiconductor studied, we find that the width of the Gaussian distribution of density of states σ and the lattice constant a are similar to the values reported for conjugated polymers. Furthermore, we show that the boundary carrier density has an important effect on the J- V characteristics. Both the maximum of carrier density and the minimum of electric field appear near the interface of NPB hole-only devices.

  19. Statistical properties of Joule heating rate, electric field and conductances at high latitudes

    Directory of Open Access Journals (Sweden)

    A. T. Aikio

    2009-07-01

    Full Text Available Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox and from similar sunspot conditions (about 1.5 years before the sunspot minimum providing an excellent set of data to study the MLT and Kp dependence of parameters with high temporal and spatial resolution. All the parameters show a clear MLT variation, which is different for low and high Kp conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for Kp≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity. An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (Kp<3 and Kp≥3. In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to auroral arcs as a result of ionosphere-magnetosphere coupling, as discussed by Aikio et al. (2004 In

  20. Statistical properties of Joule heating rate, electric field and conductances at high latitudes

    Directory of Open Access Journals (Sweden)

    A. T. Aikio

    2009-07-01

    Full Text Available Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox and from similar sunspot conditions (about 1.5 years before the sunspot minimum providing an excellent set of data to study the MLT and Kp dependence of parameters with high temporal and spatial resolution.

    All the parameters show a clear MLT variation, which is different for low and high Kp conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for Kp≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity.

    An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (Kp<3 and Kp≥3. In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to

  1. Developing suitable methods for effective characterization of electrical properties of root segments

    Science.gov (United States)

    Ehosioke, Solomon; Phalempin, Maxime; Garré, Sarah; Kemna, Andreas; Huisman, Sander; Javaux, Mathieu; Nguyen, Frédéric

    2017-04-01

    The root system represents the hidden half of the plant which plays a key role in food production and therefore needs to be well understood. Root system characterization has been a great challenge because the roots are buried in the soil. This coupled with the subsurface heterogeneity and the transient nature of the biogeochemical processes that occur in the root zone makes it difficult to access and monitor the root system over time. The traditional method of point sampling (root excavation, monoliths, minirhizotron etc.) for root investigation does not account for the transient nature and spatial variability of the root zone, and it often disturbs the natural system under investigation. The quest to overcome these challenges has led to an increase in the application of geophysical methods. Recent studies have shown a correlation between bulk electrical resistivity and root mass density, but an understanding of the contribution of the individual segments of the root system to that bulk signal is still missing. This study is an attempt to understand the electrical properties of roots at the segment scale (1-5cm) for more effective characterization of electrical signal of the full root architecture. The target plants were grown in three different media (pot soil, hydroponics and a mixture of sand, perlite and vermiculite). Resistance measurements were carried out on a single segment of each study plant using a voltmeter while the diameter was measured using a digital calliper. The axial resistance was calculated using the measured resistance and the geometric parameters. This procedure was repeated for each plant replica over a period of 75 days which enabled us to study the effects of age, growth media, diameter and length on the electrical response of the root segments of the selected plants. The growth medium was found to have a significant effect on the root electrical response, while the effect of root diameter on their electrical response was found to vary

  2. Electrical and dielectric properties of TiO2 and Fe2O3 doped fly ash

    Indian Academy of Sciences (India)

    It has been observed that these materials possess a very high relative dielectric constant and high electrical properties at room temperature. Such a high dielectric constant is one of the important parameters in capacitor fabrication and a high electrical conductivity can be used for ionic batteries and electrochemical sensors.

  3. Electrical, dielectric, and optical properties of Sb2O3–Li2O–MoO3 glasses

    Czech Academy of Sciences Publication Activity Database

    Kubliha, M.; Soltani, M.T.; Trnovcová, V.; Legouera, M.; Labaš, V.; Kostka, Petr; Le Coq, D.; Hamzaoui, M.

    2015-01-01

    Roč. 428, NOV 15 (2015), s. 42-48 ISSN 0022-3093 R&D Projects: GA ČR GAP106/12/2384 Institutional support: RVO:67985891 Keywords : lithium molybdenum–antimonite glasses * electrical conductivity * electrical relaxation * dielectric response * optical properties Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.825, year: 2015

  4. Analysis of the Mechanisms Determining the Thermal and Electrical Properties of Epoxy Nanocomposites for High Voltage Applications

    NARCIS (Netherlands)

    Tsekmes, I.A.

    2016-01-01

    The addition of microsized fillers to polymers, in order to tailor their properties, has been extensively used in many industrial applications since the 1960s. The same approach applies to the field of electrical insulation. Epoxy resin is a widely used polymer in the electrical power sector, but it

  5. Effects of the electric field on the properties of ZnO-graphene composites: a density functional theory study.

    Science.gov (United States)

    Geng, Wei; Zhao, Xuefei; Zan, Wenyan; Liu, Huanxiang; Yao, Xiaojun

    2014-02-28

    In this work, the effects of the electric field on the properties of ZnO-graphene composites were theoretically studied using density functional theory calculations. Three types of ZnO-graphene composites including composites of pristine graphene, graphene with defects as well as graphene oxide and a ZnO bilayer were studied. We calculated and analyzed the binding energies, charge transfer, band structures and work functions of the above composites under the external electric fields. The DFT calculation results demonstrate that the binding energies are sensitive to the electric field, and increasing the external electric field gives rise to stronger binding energies. The extent of charge transfer is correlated with the magnitude of the external electric field, but the band gaps are hardly affected by the external electric field. The work functions vary depending on the different structures of the composites and surface sides, and they are also tunable by the external electric field.

  6. In situ–Directed Growth of Organic Nanofibers and Nanoflakes: Electrical and Morphological Properties

    DEFF Research Database (Denmark)

    Oliveira Hansen, Roana Melina de; Madsen, Morten; Kjelstrup-Hansen, Jakob

    2010-01-01

    for electrical connection continues to be a significant hindrance toward their large-scale implementation. Here, we demonstrate in situ–directed growth of such organic nanostructures between pre-fabricated contacts, which are source–drain gold electrodes on a transistor platform (bottom-gate) on silicon dioxide......Organic nanostructures made from organic molecules such as para-hexaphenylene (p-6P) could form nanoscale components in future electronic and optoelectronic devices. However, the integration of such fragile nanostructures with the necessary interface circuitry such as metal electrodes...... patterned by a combination of optical lithography and electron beam lithography. The dimensions of the gold electrodes strongly influence the morphology of the resulting structures leading to notably different electrical properties. The ability to control such nanofiber or nanoflake growth opens...

  7. Molecular organization and electrical properties of mixed Langmuir-Blodgett multilayer thin films of polypyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, J.; Rosner, R.B.; Rubner, M.F. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Dept. of Materials Science and Engineering); Yang, X.Q.; Chen, J.; Skotheim, T.A. (Brookhaven National Lab., Upton, NY (USA))

    1989-01-01

    The molecular organization of Langmuir-Blodgett multilayer thin films containing electrically conductive polypyrrole chains dispersed throughout insulating domains of surface active pyrrole molecules was examined by several thin film spectroscopic techniques. Reflection-absorption FTIR and NEXAFS spectroscopy have revealed that the 3-ODOP (3-octadecanoyl pyrrole) surface active pyrrole molecules are highly oriented within the film with their fully extended hydrocarbon chains tilted away from the surface normal with an unusually large tilt angle of about 55{degrees}. Evidence for preferred orientation of the polypyrrole chains was also found. The multilayer films were found to exhibit very large dielectric constants (>100) at low frequencies and enormous conductivity anisotropies. These unusual electrical properties can be directly attributed to the molecular organization of the film which consists of polypyrrole chains sandwiched between well ordered layers of 3-ODOP molecules. 7 refs., 3 figs.

  8. In situ–Directed Growth of Organic Nanofibers and Nanoflakes: Electrical and Morphological Properties

    Directory of Open Access Journals (Sweden)

    de Oliveira Hansen Roana

    2011-01-01

    Full Text Available Abstract Organic nanostructures made from organic molecules such as para-hexaphenylene (p-6P could form nanoscale components in future electronic and optoelectronic devices. However, the integration of such fragile nanostructures with the necessary interface circuitry such as metal electrodes for electrical connection continues to be a significant hindrance toward their large-scale implementation. Here, we demonstrate in situ–directed growth of such organic nanostructures between pre-fabricated contacts, which are source–drain gold electrodes on a transistor platform (bottom-gate on silicon dioxide patterned by a combination of optical lithography and electron beam lithography. The dimensions of the gold electrodes strongly influence the morphology of the resulting structures leading to notably different electrical properties. The ability to control such nanofiber or nanoflake growth opens the possibility for large-scale optoelectronic device fabrication.

  9. Structure, thermal stability and electrical properties of reduced graphene/poly(vinylidene fluoride) nanocomposite films.

    Science.gov (United States)

    Han, Peng; Fan, Jingbo; Zhu, Lin; Min, Chunying; Shen, Xiangqian; Pan, Tiezheng

    2012-09-01

    The reduced graphene/poly(vinylidene fluoride) nanocomposite films were prepared by the solution casting-thermal reduction process using graphene oxide (GO) and poly(vinylidene fluoride) (PVDF) resin. With the presence of reduced graphene (RG) nano sheets in the nanocomposite, the structure of PVDF is transformed from alpha to beta phase, and the beta phase fraction and its crystallinity are largely affected by the RG content. The PVDF thermal stability is improved by the RG introduction, with about 15 degrees C increase of the half-life of PVDF decomposition temperature. The RG/PVDF nanocomposites show a better electrical conductivity than that for the GO/PVDF nanocomposites. At a low RG content (0.8 wt.%), the dielectric constant of RG/PVDF nanocomposite film with a very low loss tangent is dramatically increased from about 6 to 23. The mechanisms for the thermal stability and electrical property improvements are discussed.

  10. Synergistically tuning the electrical and thermal transport properties of CdO:Cu thermoelectric ceramics

    Science.gov (United States)

    Fu, Guangsheng; Gao, Linjie; Liu, Ran; Zha, Xinyu; Wang, Jianglong; Wang, Shufang

    2017-07-01

    The thermoelectric performance of CdO ceramics was optimized by synergistically tuning their electrical and thermal transport properties via Cu doping. The introduction of Cu led to an increase in carrier concentration and mobility simultaneously for samples with Cu content less than 3%. An improvement in power factor was obtained due to decreased electrical resistivity and a moderate Seebeck coefficient. A small amount of Cu doping was also verified to be effective in suppressing the heat transfer of CdO ceramics owing to the enhanced phonon scattering from point defects and grain boundaries. Benefiting from the increase in power factor and decrease in thermal conductivity, enhanced ZT values were achieved in all doped samples, indicating that Cu doping is an effective strategy to promote the thermoelectric performance of CdO ceramics.

  11. Structural and Electrical Properties of the YSZ/STO/YSZ Heterostructure

    Directory of Open Access Journals (Sweden)

    Yue Fan

    2014-01-01

    Full Text Available The heterostructure thin films of yttria-stabilized zirconia (YSZ/strontium titanate (STO/YSZ with various thicknesses were deposited on MgO single crystal substrate by pulsed laser deposition (PLD method. The structural and electrical properties of the YSZ/STO/YSZ heterostructure were studied through X-ray diffraction (XRD and electrical conductivity measurements. The in-plane conductivities of the thin films were measured and compared with that of the bulk sample. The highest conductivities were reported for those samples with the thinnest YSZ (220 layers. The observed enhancement in the lateral ionic conductivity was probably caused by the combination of the misfit dislocation density and elastic strain in the interfaces. The enhanced ionic mobility was discussed in terms of the disorder introduced in the oxygen sublattice through the epitaxial strain at the interfaces.

  12. Electrical Properties of Partial Carbonized Nanoporous Resin Based on Resorcinol-Formaldehyde

    Directory of Open Access Journals (Sweden)

    Imededdine NAJEH

    2014-05-01

    Full Text Available Organic xerogel compounds were prepared by sol-gel method from resorcinol- formaldehyde mixtures in acetone using picric acid as catalyst. The electrical properties of the obtained nanoporous carbon structures were explored by changing the pyrolysis temperature. In this study the electrical conductivity σ can be expressed as σ =/σ0exp(-Eσ/kT, where Eσ depends on the carbonized temperature. The dc and ac conductivities of the obtained amorphous carbon have been investigated from 80 to 300 °C and in the frequency range between 40 and 106 Hz for samples pyrolysed at different temperatures in the insulator-metal transition range. The temperature dependence of samples pyrolysed at low temperatures (Tp=600–675 °C follows a Mott law, whereas samples pyrolysed at high temperature (Tp=1000 °C show an Arrhenius dependence.

  13. Cold plasma welding of polyaniline nanofibers with enhanced electrical and mechanical properties

    Science.gov (United States)

    Ye, Dong; Yu, Yao; Liu, Lin; Lu, Xinpei; Wu, Yue

    2015-12-01

    Joining conducting polymer (CP) nanofibers into an interconnected porous network can result in good mechanical and electrical contacts between nanofibers that can be beneficial for the high performance of CP-based devices. Here, we demonstrate the cold welding of polyaniline (PAni) nanofiber loose ends with cold plasma. The room-temperature and atmospheric-pressure helium micro-plasma jet launches highly charged ion bullets at a PAni nanofiber target with high precision and the highly charged ion bullet selectively induces field emission at the sharp nanofiber loose ends. This technique joins nanofiber tips without altering the morphology of the film and protonation thus leading to significantly enhanced electrical and mechanical properties. In addition, this technique has high spatial resolution and is able to selectively weld and dope regions of nanofiber film with promising novel device applications.

  14. Comparative study between structural and electrical properties of geopolymers applied to a green concrete

    Science.gov (United States)

    Montaño, A. M.; González, C. P.; Pérez, J.; Royero, C.; Sandoval, D.; Gutiérrez, J.

    2013-11-01

    This work shows a comparative analysis of geopolymers obtained by alkaline activation of two aluminosilicates: bentonite and metakaolin. With the goal of to replace some cement percentage, both aluminosilicates were added in several proportions (10, 20 and 30%) to concrete mixes. Portland Type I cement was used to prepare the reference concrete (without geopolymer). X-ray diffraction of geopolymers allowed to find new crystallographic phases that was not present in precursor's minerals. To evaluate mechanical properties of concrete prepared with geopolymers, test tubes with 7, 14, 28 and 90 days as setting time were used. Chemical resistance and Electrical impedance of concrete mixes were also measured. Results shows that cementitious material obtained from metakaolin exhibit the best compressive strength. On the other hand, those materials derived from bentonite, have a high electrical resistance so that, they protected reinforced concrete better that Portland does.

  15. The Positive Effects of Hydrophobic Fluoropolymers on the Electrical Properties of MoS2 Transistors

    Directory of Open Access Journals (Sweden)

    Somayyeh Rahimi

    2016-08-01

    Full Text Available We report the improvement of the electrical performance of field effect transistors (FETs fabricated on monolayer chemical vapor deposited (CVD MoS2, by applying an interacting fluoropolymer capping layer (Teflon-AF. The electrical characterizations of more than 60 FETs, after applying Teflon-AF cap, show significant improvement of the device properties and reduced device to device variation. The improvement includes: 50% reduction of the average gate hysteresis, 30% reduction of the subthreshold swing and about an order of magnitude increase of the current on-off ratio. These favorable changes in device performance are attributed to the reduced exposure of MoS2 channels to the adsorbates in the ambient which can be explained by the polar nature of Teflon-AF cap. A positive shift in the threshold voltage of all the measured FETs is observed, which translates to the more desirable enhancement mode transistor characteristics.

  16. Microstructural and electrical properties of cordierite-based ceramics obtained after two-step sintering technique

    Directory of Open Access Journals (Sweden)

    Obradović Nina

    2016-01-01

    Full Text Available Cordierite-based ceramic materials are attracting much interest for their various applications in industry, for manufacturing multilayer circuit boards, catalytic converters, filters, thermal insulation, kiln furniture, components of portable electronic devices, etc. In order to reduce production costs and modify cordierite-based materials, mechanical activation can be used. In this study, microstructural and electrical properties of mechanically activated MgO-Al2O3-SiO2 system have been analyzed. The mixtures of MgO-Al2O3-SiO2 powders were mechanically activated in a planetary ball mill for the time periods from 0 to 160 min. Morphological investigations have been performed on the obtained powders. The effects of activation and two-step sintering process on microstructure were investigated by scanning electron microscopy (SEM. Electrical measurements showed variations of the dielectric constant (εr and loss tangent (tan δ as a function of time of mechanical treatment.

  17. The measurement of magnetic properties of electrical sheet steel - survey on methods and situation of standards

    CERN Document Server

    Sievert, J

    2000-01-01

    A brief review of the different requirements for magnetic measurement techniques for material research, modelling of material properties and grading of the electrical sheet steel for trade purposes is presented. In relation to the main application of laminated electrical steel, this paper deals with AC measurement techniques. Two standard methods, Epstein frame and Single Sheet Tester (SST), producing different results, are used in parallel. This dilemma was analysed in detail. The study leads to a possible solution of the problem, i.e. the possibility of converting the results of one of the two methods into the results of the other in order to satisfy the users of the Epstein method and, at the same time, to improve the acceptance of the more economical SST method.

  18. Plasma Polypyrrole Coated Hybrid Composites with Improved Mechanical and Electrical Properties for Aerospace Applications

    Science.gov (United States)

    Yavuz, Hande; Bai, Jinbo

    2017-09-01

    This paper deals with the dielectric barrier discharge assisted continuous plasma polypyrrole deposition on CNT-grafted carbon fibers for conductive composite applications. The simultaneous effects of three controllable factors have been studied on the electrical resistivity (ER) of these two material systems based on multivariate experimental design methodology. A posterior probability referring to Benjamini-Hochberg (BH) false discovery rate was explored as multiple testing corrections of the t-test p values. BH significance threshold of 0.05 was produced truly statistically significant coefficients to describe ER of two material systems. A group of plasma modified samples was chosen to be used for composite manufacturing to drive an assessment of interlaminar shear properties under static loading. Transversal and longitudinal electrical resistivity (DC, ω =0) of composite samples were studied to compare both the effects of CNT grafting and plasma modification on ER of resultant composites.

  19. Electrical Characterization and Hydrogen Peroxide Sensing Properties of Gold/Nafion:Polypyrrole/MWCNTs Electrochemical Devices

    Science.gov (United States)

    Scandurra, Graziella; Arena, Antonella; Ciofi, Carmine; Saitta, Gaetano

    2013-01-01

    Electrochemical devices using as substrates copier grade transparency sheets are developed by using ion conducting Nafion: polypyrrole mixtures, deposited between gold bottom electrodes and upper electrodes based on Multi Walled Carbon Nanotubes (MWCNTs). The electrical properties of the Nafion:polypyrrole blends and of the gold/Nafion:polypyrrole/MWCNTs devices are investigated under dry conditions and in deionized water by means of frequency dependent impedance measurements and time domain electrical characterization. According to current-voltage measurements carried out in deionized water, the steady state current forms cycles characterized by redox peaks, the intensity and position of which reversibly change in response to H2O2, with a lower detection limit in the micromolar range. The sensitivity that is obtained is comparable with that of other electrochemical sensors that however, unlike our devices, require supporting electrolytes. PMID:23529125

  20. Influence of the nanotube oxidation on the rheological and electrical properties of CNT/HDPE composites

    Energy Technology Data Exchange (ETDEWEB)

    Nobile, Maria Rossella, E-mail: mrnobile@unisa.it; Somma, Elvira; Valentino, Olga; Neitzert, Heinz-Christoph [Department of Industrial Engineering – DIIn - Università di Salerno Via Giovanni Paolo II, 132 - 84084 Fisciano (Italy); Simon, George [Department of Materials Engineering, Monash University, Clayton, Victoria 3800 (Australia)

    2016-05-18

    Rheological and electrical properties of nanocomposites based on multi-walled carbon nanotubes (MWNTs) and high density polyethylene (HDPE), prepared by melt mixing in a micro-twin screw extruder, have been investigated. The effect of MWNT concentration (0.5 and 2.5 wt %) and nanotube surface treatment (oxidative treatment in a tubular furnace at 500°C for 1 hr in a 95% nitrogen, 5% oxygen atmosphere) has been analyzed. It has been found that the sample conductivity with oxidation of the nanotubes decreases more than 2 orders of magnitude. Scanning electron microscopy showed good adhesion and dispersion of nanotubes in the matrix, independently of the surface treatment. Electrical and rheological measurements revealed that the oxidative treatment, causing some reduction of the MWNT quality, decreases the efficiency of the nanotube matrix interaction.

  1. Asymmetric surface dielectric barrier discharge in air at atmospheric pressure: electrical properties and induced airflow characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Pons, Jerome; Moreau, Eric; Touchard, Gerard [LEA, University of Poitiers/CNRS/ENSMA, Bd. Curie, Teleport 2, BP 30179, 86962 Futuroscope Cedex (France)

    2005-10-07

    The electrical properties of an asymmetric surface dielectric barrier discharge in atmospheric air have been investigated experimentally. The discharge is used for airflow production close to the dielectric surface, and the time-averaged flow velocity spatial profiles have been measured. Velocities of up to 3.5 m s{sup -1} at heights of 1-2 mm are reached when filamentary discharges with current peaks up to 20 mA are produced along the surface. In terms of powers, mechanical powers (output) of a few milliwatts are obtained for electrical powers (input) up to 10 W. Variation laws or behaviour with several discharge parameters (applied voltage waveform, distance between electrodes, dielectric thickness and permittivity) have been experimentally determined.

  2. Modelling Feedback Excitation, Pacemaker Properties and Sensory Switching of Electrically Coupled Brainstem Neurons Controlling Rhythmic Activity.

    Science.gov (United States)

    Hull, Michael J; Soffe, Stephen R; Willshaw, David J; Roberts, Alan

    2016-01-01

    What cellular and network properties allow reliable neuronal rhythm generation or firing that can be started and stopped by brief synaptic inputs? We investigate rhythmic activity in an electrically-coupled population of brainstem neurons driving swimming locomotion in young frog tadpoles, and how activity is switched on and off by brief sensory stimulation. We build a computational model of 30 electrically-coupled conditional pacemaker neurons on one side of the tadpole hindbrain and spinal cord. Based on experimental estimates for neuron properties, population sizes, synapse strengths and connections, we show that: long-lasting, mutual, glutamatergic excitation between the neurons allows the network to sustain rhythmic pacemaker firing at swimming frequencies following brief synaptic excitation; activity persists but rhythm breaks down without electrical coupling; NMDA voltage-dependency doubles the range of synaptic feedback strengths generating sustained rhythm. The network can be switched on and off at short latency by brief synaptic excitation and inhibition. We demonstrate that a population of generic Hodgkin-Huxley type neurons coupled by glutamatergic excitatory feedback can generate sustained asynchronous firing switched on and off synaptically. We conclude that networks of neurons with NMDAR mediated feedback excitation can generate self-sustained activity following brief synaptic excitation. The frequency of activity is limited by the kinetics of the neuron membrane channels and can be stopped by brief inhibitory input. Network activity can be rhythmic at lower frequencies if the neurons are electrically coupled. Our key finding is that excitatory synaptic feedback within a population of neurons can produce switchable, stable, sustained firing without synaptic inhibition.

  3. Characterization of peat-electrical properties by means of geoelectrical measurements

    Science.gov (United States)

    Walter, Judith; Lück, Erika; Zeitz, Jutta

    2013-04-01

    Peatlands have an important function for the storage of global carbon. These functions are reduced significantly due to intensive agricultural drainage which leads to decomposition of the organic material and hence to the loss of carbon. In order to reduce these losses, assessments of the peatlands in their current function as a carbon sink, and adequate management are required. In this context, information about both the peat thickness and their condition (degree of decomposition) are crucial. Methods which can estimate the latter in the field other than time-consuming conventional coring techniques are still missing in practice. Our approach is to gather this information in fen soils by means of non-intrusive geoelectrical techniques through the measurement of electrical conductivity of bulk soil (ECb), which is correlated with parameters such as cation exchange capacity (CEC), organic carbon (OC) and the electrical conductivity of the soil solution (ECe), which, furthermore, are functions of the peat condition. In order to assess the field-applicability of this technique, we examined as a first step the electrical properties of peat in different stages of decomposition by measuring ECb of undisturbed samples derived from various study sites in the laboratory. All parameters (ECe, CEC, OC, bulk density, pH-value and volumetric water content), which may potentially influence the ECb of peat were analyzed simultaneously. Multiple regression analysis revealed a strong response of ECb on ECe followed by CEC and water content if all samples from different locations were incorporated. ECe explained about 60%, CEC 30% and volumetric water content 10% of variability in ECb. Whereas CEC was primarily a function of the degree of decomposition of the peat, ECe levels varied from site to site and no correlation with the latter could be identified. Therefore, we assume that the estimation of peat properties, describing its condition, through electrical measurements is

  4. Optical and electrical properties of TiOPc doped Alq{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ramar, M.; Suman, C. K., E-mail: sumanck@nplindia.org; Tyagi, Priyanka; Srivastava, R. [CSIR-Network of Institutes for Solar Energy CSIR - National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi -110012 (India)

    2015-06-24

    The Titanyl phthalocyanine (TiOPc) was doped in Tris (8-hydroxyquinolinato) aluminum (Alq3) with different concentration. The thin film of optimized doping concentration was studied extensively for optical and electrical properties. The optical properties, studied using ellipsometry, absorption and photoluminescence. The absorption peak of Alq{sub 3} and TiOPc was observed at 387 nm and 707 nm and the photo-luminescence intensity (PL) peak of doped thin film was observed at 517 nm. The DC and AC electrical properties of the thin film were studied by current density-voltage (J-V) characteristics and impedance over a frequency range of 100 Hz - 1 MHz. The electron mobility calculated from trap-free space-charge limited region (SCLC) is 0.17×10{sup −5} cm{sup 2}/Vs. The Cole-Cole plots shows that the TiOPc doped Alq{sub 3} thin film can be represented by a single parallel resistance R{sub P} and capacitance C{sub P} network with a series resistance R{sub S} (10 Ω). The value of R{sub P} and C{sub P} at zero bias was 1587 Ω and 2.568 nF respectively. The resistance R{sub P} decreases with applied bias whereas the capacitance C{sub P} remains almost constant.

  5. Experimental Investigation of Surface Layer Properties of High Thermal Conductivity Tool Steel after Electrical Discharge Machining

    Directory of Open Access Journals (Sweden)

    Rafał Świercz

    2017-12-01

    Full Text Available New materials require the use of advanced technology in manufacturing complex shape parts. One of the modern materials widely used in the tool industry for injection molds or hot stamping dies is high conductivity tool steel (HTCS 150. Due to its hardness (55 HRC and thermal conductivity at 66 W/mK, this material is difficult to machine by conventional treatment and is being increasingly manufactured by nonconventional technology such as electrical discharge machining (EDM. In the EDM process, material is removed from the workpiece by a series of electrical discharges that cause changes to the surface layers properties. The final state of the surface layer directly influences the durability of the produced elements. This paper presents the influence of EDM process parameters: discharge current Ic and the pulse time ton on surface layer properties. The experimental investigation was carried out with an experimental methodology design. Surface layers properties including roughness 3D parameters, the thickness of the white layer, heat affected zone, tempered layer and occurring micro cracks were investigated and described. The influence of the response surface methodology (RSM of discharge current Ic and the pulse time ton on the thickness of the white layer and roughness parameters Sa, Sds and Ssc were described and established.

  6. What the electrical impedance can tell about the intrinsic properties of an electrodynamic shaker.

    Science.gov (United States)

    Lütkenhöner, Bernd

    2017-01-01

    Small electrodynamic shakers are becoming increasingly popular for diagnostic investigations of the human vestibular system. More specifically, they are used as mechanical stimulators for eliciting a vestibular evoked myogenic potential (VEMP). However, it is largely unknown how shakers perform under typical measurement conditions, which considerably differ from the normal use of a shaker. Here, it is shown how the basic properties of a shaker can be determined without requiring special sensors such as accelerometers or force gauges. In essence, the mechanical parts of the shaker leave a signature in the electrical impedance, and an interpretation of this signature using a simple model allows for drawing conclusions about the properties of the shaker. The theory developed (which is quite general so that it is usable also in other contexts) is applied to experimental data obtained for the minishaker commonly used in VEMP measurements. It is shown that the experimental conditions substantially influence the properties of the shaker. Relevant factors are, in particular, the spatial orientation of the shaker (upright, horizontal or upside-down) and the static force acting on the table of the shaker (which in a real measurement corresponds to the force by which the shaker is pressed against the test person's head). These results underline the desirability of a proper standardization of VEMP measurements. Direct measurements of displacement and acceleration prove the consistency of the conclusions derived from the electrical impedance.

  7. Crystallographic, Magnetic, Thermal, and Electric Transport Properties in UPtIn Single Crystal

    Science.gov (United States)

    Matsumoto, Yuji; Haga, Yoshinori; Tateiwa, Naoyuki; Yamamoto, Etsuji; Fisk, Zachary

    2018-02-01

    We have studied the crystallographic, magnetic, thermal, and electric transport properties in UPtIn, one of the UTX (T = transition metal, X = Al, Ga, In) families with the hexagonal ZrNiAl structure. A single crystal of UPtIn was prepared by the flux method for the first time. Crystallographic parameters are determined. UPtIn has strong Ising character, the magnetic easy axis being the c-axis. These results determined magnetic properties are consistent with the magnetic structure obtained by neutron scattering measurements. The residual resistivity of our single crystal is 27.9 µΩ cm which is one-third times smaller than that of polycrystalline sample. Specific heat (C) measurements show that the phase transition at 10.5 K, although the antiferromagnetic order takes place at 22 K prepared by arc melt and at 15 K prepared by solid reaction, indicating that the physical properties of UPtIn are dependent on the sample preparation. C/T deviates from T-linear behavior below 1.4 K, indicating that the electronic specific heat coefficient γ is much smaller than that of previous study. The resistivity is almost independent to the temperature below 3.7 K and A coefficient of the quadratic temperature dependence of electrical resistivity is small, indicating that the mass enhancement is small. These results indicate that UPtIn is not a heavy-fermion system.

  8. Measurement of insulating and dielectric properties of acrylic elastomer membranes at high electric fields

    Science.gov (United States)

    Di Lillo, L.; Schmidt, A.; Carnelli, D. A.; Ermanni, P.; Kovacs, G.; Mazza, E.; Bergamini, A.

    2012-01-01

    This work reports on the investigation of VHB 4910 acrylic elastomer insulating and dielectric properties. This material is widely exploited for the realization of actuators with large deformations, dielectric elastomer actuators (DEA), and belongs to the group of so-called electroactive polymers (EAP). Extensive investigations concerning its mechanical properties are available in literature while its electric behavior at working conditions has not received the same level of attention. In this work, the relative permittivity and the volume resistivity have been measured on VHB 4910 membranes under different fixed stretch conditions (λ1, λ2 = 3, 3.6, 4, 5) using circular gold electrodes sputtered onto both sides of the specimens. The measured values of relative permittivity are in fairly good agreement with the results previously published by other groups. The volume resistivity, at field values close to the operational ones, has shown a field-dependent behavior revealing dissipative properties that should be considered in real applications. Further, measurements on circular actuators verify these findings. Consequences for modeling of VHB 4910 are drawn and new material model parameters proposed to account for the value of relative permittivity at high electric fields.

  9. Electrical resistivity and thermal properties of compatibilized multi-walled carbon nanotube/polypropylene composites

    Directory of Open Access Journals (Sweden)

    A. Szentes

    2012-06-01

    Full Text Available The electrical resistivity and thermal properties of multi-walled carbon nanotube/polypropylene (MWCNT/PP composites have been investigated in the presence of coupling agents applied for improving the compatibility between the nanotubes and the polymer. A novel olefin-maleic-anhydride copolymer and an olefin-maleic-anhydride copolymer based derivative have been used as compatibilizers to achieve better dispersion of MWCNTs in the polymer matrix. The composites have been produced by extrusion followed by injection moulding. They contained different amounts of MWCNTs (0.5, 2, 3 and 5 wt% and coupling agent to enhance the interactions between the carbon nanotubes and the polymer. The electrical resistivity of the composites has been investigated by impedance spectroscopy, whereas their thermal properties have been determined using a thermal analyzer operating on the basis of the periodic thermal perturbation method. Rheological properties, BET-area and adsorption-desorption isotherms have been determined. Dispersion of MWCNTs in the polymer has been studied by scanning electron microscopy (SEM.

  10. Study of Optical and Electrical Properties of Organic Thin Films for Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Jan Pospisil

    2015-09-01

    Full Text Available The paper deals with the study of optical, electrical and dielectric properties of thin film organic materials suitable for the preparation of optoelectronic devices (e.g. photodiodes, phototransistors, photovoltaic cells. As active layers palladium phthalocyanine (PdPc[t-Bu]4, fullerene (acceptor material, PCBM and their mixture (9:5 mass % were used. Thin films were prepared by two methods: by spin coating (Chemat technology Spin Coater and by material inkjet printing (Dimatix Materials Printer DMP-2800. UV-VIS spectroscopy and ellipsometry were used to study the optical properties. The paper also presents results of electrical and dielectric measurements. We found out that the properties of all structures prepared by spin coating depend on the rotational speed of spin coater, on the mode of solution casting (static, dynamic and in the case of material inkjet printing they are too much influenced by the substrate. Samples prepared on the substrate at 60 °C showed a photovoltaic effect with fill factor about 0.25 and the conversion efficiency about 0.2 %.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7278

  11. Effect of microdrops deformation on electrical and rheological properties of magnetic fluid emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Zakinyan, Arthur R., E-mail: zakinyan.a.r@mail.ru; Dikansky, Yuri I.

    2017-06-01

    The magnetic fluid emulsions with low interfacial tension have been studied experimentally. The shape deformation of the dispersed phase microdrops under the action of comparatively weak magnetic field has been observed. The effect of microdrops deformation on the macroscopic properties of the emulsion has been investigated. The anisotropic character of emulsion properties in the presence of external magnetic field has been demonstrated. The emulsion dielectric permeability has been measured as a function of the magnetic field strength, the emulsion concentration, and the angle between electrical and magnetic fields. The influence of the droplets deformation under the magnetic field on the rheological behavior of the emulsion has been observed. The obtained results have been analyzed and discussed. - Highlights: • The dispersed phase drops of emulsion studied can be deformed by magnetic field. • The emulsion becomes anisotropic under the action of external field. • The emulsion electrical properties depends on magnetic field strength and direction. • The emulsion rheological behavior can be controlled by external magnetic field.

  12. Electrical and optical properties of Zn-In-Sn-O transparent conducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, Paz, E-mail: pazcarreras@ub.edu; Antony, Aldrin; Rojas, Fredy; Bertomeu, Joan

    2011-12-01

    Indium tin oxide (ITO) is one of the widely used transparent conductive oxides (TCO) for application as transparent electrode in thin film silicon solar cells or thin film transistors owing to its low resistivity and high transparency. Nevertheless, indium is a scarce and expensive element and ITO films require high deposition temperature to achieve good electrical and optical properties. On the other hand, although not competing as ITO, doped Zinc Oxide (ZnO) is a promising and cheaper alternative. Therefore, our strategy has been to deposit ITO and ZnO multicomponent thin films at room temperature by radiofrequency (RF) magnetron co-sputtering in order to achieve TCOs with reduced indium content. Thin films of the quaternary system Zn-In-Sn-O (ZITO) with improved electrical and optical properties have been achieved. The samples were deposited by applying different RF powers to ZnO target while keeping a constant RF power to ITO target. This led to ZITO films with zinc content ratio varying between 0 and 67%. The optical, electrical and morphological properties have been thoroughly studied. The film composition was analysed by X-ray Photoelectron Spectroscopy. The films with 17% zinc content ratio showed the lowest resistivity (6.6 Multiplication-Sign 10{sup -4} Ohm-Sign cm) and the highest transmittance (above 80% in the visible range). Though X-ray Diffraction studies showed amorphous nature for the films, using High Resolution Transmission Electron Microscopy we found that the microstructure of the films consisted of nanometric crystals embedded in a compact amorphous matrix. The effect of post deposition annealing on the films in both reducing and oxidizing atmospheres were studied. The changes were found to strongly depend on the zinc content ratio in the films.

  13. Relationship between propagation direction of gravity waves in OH and OI airglow images and VHF radar echo occurrence during the SEEK-2 campaign

    Directory of Open Access Journals (Sweden)

    F. Onoma

    2005-10-01

    Full Text Available We report simultaneous observations of atmospheric gravity waves (AGW in OI (557.7nm and OH airglow images and VHF radar backscatter from field-aligned irregularities (FAI in the E-region during the SEEK-2 (Sporadic-E Experiment over Kyushu 2 campaign period from 29 July to 9 August 2002. An all-sky imager was operated at Nishino-Omote (30.5 N, 130.1 E, Japan. On 14 nights, 17 AGW events were detected in OI and OH airglow images. AGW propagated mostly toward the northeast or southeast. From comparison with the E-region FAI occurrence, which is detected by a nearby VHF radar (31.57MHz, we found that AGW tended to propagate southeastward during FAI events. This result suggests that the interaction between AGW and E-region plasma plays an important role in generating FAI. Furthermore, polarization electric fields generated directly by AGW may contribute to the FAI generation.

    Keywords. Atmospheric composition and structure (Airglow and aurora, Ionosphere (Ionospheric irregularities, Mid-latitude ionosphere

  14. MECHANICAL, ELECTRICAL, AND THERMAL PROPERTIES OF MALEIC ANHYDRIDE MODIFIED RICE HUSK FILLED PVC COMPOSITES

    OpenAIRE

    Navin Chand; Bhajan Das Jhod

    2008-01-01

    Unmodified and modified rice husk powder filled PVC composites were prepared having different amounts of rice husk powder. Mechanical, thermal, and electrical properties of these composites were determined. The tensile strength of rice husk powder PVC composites having 0, 10, 20, 30, and 40 weight percent of rice husk powder was found to be 33.9, 19.4, 18.1, 14.6, and 9.5 MPa, respectively. Adding of maleic anhydride- modified rice husk powder improved the tensile strength of rice husk powder...

  15. Effect of annealing atmosphere on optic-electric properties of Zn O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bueno, C. [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria, Blvd. Valsequillo y Av. San Claudio s/n, 72570 Puebla (Mexico); Pacio, M.; Juarez, H. [Benemerita Universidad Autonoma de Puebla, Posgrado en Dispositivos Semiconductores, Av. San Claudio y 14 Sur, 72450 Puebla (Mexico); Osorio, E. [Universidad de Quinta Roo, Blvd. Bahia s/n, esquina Ignacio Comonfort, El Bosque, 77019 Chetumal, Quintana Roo (Mexico); Perez, R., E-mail: cba3009@gmail.com [Benemerita Universidad Autonoma de Puebla, Facultad de Ingenieria Quimica, Av. San Claudio y 18 Sur, 72570 Puebla (Mexico)

    2017-11-01

    In this work the study of structural, morphologic characteristics, optical and electrical properties of the thin films of Zn O in temperatures and annealing atmospheres different was realized. The films were obtained by the sol-gel method, utilizing zinc acetate dihydrate as the precursor, monoethanolamine (Mea) as a stabilizing agent and 2-methoxyethanol as a solvent and deposited by spin-coating. The films were crystallized at 600, 800 and 1000 degrees Celsius in oxygen and nitrogen atmospheres. The results obtained by XRD, Sem, photoluminescence and Hall effects of the Zn O films were related and depend strongly on the temperature and atmosphere annealing. (Author)

  16. Electrical properties and scaling behaviour of Sm doped CaF2 ...

    Indian Academy of Sciences (India)

    Abstract. The electrical properties for 20Bi2O3–60B2O3 (20−x)–CaF2–xSm2O3 glasses (0 ≤ x ≤ 2) were measured in the temperature range 297 K up to 629 K and in the frequency range 0·1–100 kHz. The d.c. and a.c. conduc- tivity values and the dielectric loss (tan δ) values were found to increase with increasing ...

  17. Enhanced Thermal and Electrical Properties of Polystyrene-Graphene Nanofibers via Electrospinning

    Directory of Open Access Journals (Sweden)

    Yan Li

    2016-01-01

    Full Text Available Polystyrene- (PS- graphene nanoplatelets (GNP (0.1, 1, and 10 wt.% nanofibers were successfully produced via electrospining of dimethyformamide- (DMF- stabilized GNP and PS solutions. Morphological analysis of the composite nanofibers confirmed uniform fiber formation and good GNP dispersion/distribution within the PS matrix. The good physical properties of GNP produced by liquid exfoliation were transferred to the PS nanofibers. GNP modified PS nanofibers showed a 6-fold increase in the thermal conductivity and an increase of 7-8 orders of magnitude in electrical conductivity of the nanofibers at 10 wt.% GNP loading.

  18. Electrical properties of highly conducting Sno2:Sb nanocrystals synthesized using a nonaqueous sol gel method

    OpenAIRE

    Conti, Tiago Góes; Chiquito, A. J.; Silva, Rafael Oliveira da; Longo, Elson [UNESP; Leite, Edson Roberto

    2010-01-01

    This work describes the synthesis of highly conducting antimony-doped tin oxide (ATO) nanocrystals prepared via a nonaqueous sol–gel route in the size range of 4–6 nm and provides insights into its electrical properties. The antimony composition was varied from 1 to 18 mol% and the lowest resistivity (4.0 × 10−4Ω·cm) was observed at room temperature in the SnO2:8.8 mol% Sb composition. The samples were evaluated by X-ray diffraction, high-resolution transmission electron microscopy, energy-di...

  19. Microwave atomic force microscopy imaging for nanometer-scale electrical property characterization.

    Science.gov (United States)

    Zhang, Lan; Ju, Yang; Hosoi, Atsushi; Fujimoto, Akifumi

    2010-12-01

    We introduce a new type of microscopy which is capable of investigating surface topography and electrical property of conductive and dielectric materials simultaneously on a nanometer scale. The microwave atomic force microscopy is a combination of the principles of the scanning probe microscope and the microwave-measurement technique. As a result, under the noncontact AFM working conditions, we successfully generated a microwave image of a 200-nm Au film coating on a glass wafer substrate with a spatial resolution of 120 nm and a measured voltage difference of 19.2 mV between the two materials.

  20. Understanding the optical and electrical properties of a new photorefractive potassium niobate crystal

    Energy Technology Data Exchange (ETDEWEB)

    Evans, D.R. [Air Force Research Laboratory, Materials and Manufacturing Directorate Wright-Patterson Air Force Base, OH 45433 (United States)]. E-mail: dean.evans@wpafb.af.mil; Cook, G. [Air Force Research Laboratory, Materials and Manufacturing Directorate Wright-Patterson Air Force Base, OH 45433 (United States); Universal Technology Corporation, 1270 N. Fairfield Road, Dayton, OH 45432 (United States); Carns, J.L. [Air Force Research Laboratory, Materials and Manufacturing Directorate Wright-Patterson Air Force Base, OH 45433 (United States); Anteon Corporation, 5100 Springfield Pike Suite 509, Dayton, OH 45431 (United States); Saleh, M.A. [Air Force Research Laboratory, Materials and Manufacturing Directorate Wright-Patterson Air Force Base, OH 45433 (United States); UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH 45432 (United States); Basun, S.A. [A. F. Ioffe Physico-Technical Institute, Polytechnicheskaya 26, 194021, St. Petersburg (Russian Federation); Seim, J.M. [VLOC, 7826 Photonics Drive, New Port Richey, FL 34655 (United States); Mizell, G.J. [VLOC, 7826 Photonics Drive, New Port Richey, FL 34655 (United States)

    2006-07-15

    Optical and electrical measurements have been made on a new codoped potassium niobate crystal that yields a significant increase in linear absorption, photocurrent, and photorefractive beam coupling efficiency. The Ag impurity enters the K site, changing the local field in the lattice. The Fe in the Nb site, perturbed by the replacement of the next near-neighbor K with Ag, is responsible for the enhanced linear and nonlinear properties. The modified material parameters result in an increase of the photorefractive counter-propagating two-beam coupling efficiency.

  1. Temperature Dependent Electrical and Micromechanical Properties of Lanthanum Titanate with Additions of Yttria

    Science.gov (United States)

    Goldsby, Jon C.

    2003-01-01

    Lanthanum titanate (La2Ti2O7) a layered distorted perovskite (1) with space group Pna2(sub 1) has been shown to have potential as a high temperature piezoelectric (2). However this highly refractory oxide compound must be consolidated at relatively high temperatures approximately 1400 C. Commercial La2Ti207 powders were mechanically alloyed with additions of Y2O3 to lower the consolidation temperature by 300 C and to provide post processing mechanical stability. Temperature dependent electrical, elastic and anelastic behavior were selected as nondestructive means of evaluating the effects of yttria on the properties of this ferroceramic material.

  2. Effect of Yttrium on the Microstructure and Properties of Pt-Ir Electrical Contact Materials

    Science.gov (United States)

    Wang, Saibei; Sun, Yong; Wang, Song; Peng, Mingjun; Liu, Manmen; Duan, Yonghua; Chen, Yongtai; Yang, Youcai; Chen, Song; Li, Aikun; Xie, Ming

    2017-10-01

    The Pt-10Ir and Pt-10Ir-1Y were prepared by high frequency induction melting, then the samples were obtained by powder metallurgy, hot extrusion and drawing. The influence of Y addition on microstructure and electrical contact properties of Pt-10Ir alloy has been investigated by using optical microscopy, SEM, electronic balance and the contact material test system. The results show that the addition of Y leads to the micro-structural refinement and directional change of material transfer, but has almost no influence on erosion morphology.

  3. Tissue Electrical Property Mapping from Zero Echo-Time Magnetic Resonance Imaging

    OpenAIRE

    Lee, Seung-Kyun; Bulumulla, Selaka; Wiesinger, Florian; Sacolick, Laura; Sun, Wei; Hancu, Ileana

    2014-01-01

    The capability of magnetic resonance imaging (MRI) to produce spatially resolved estimation of tissue electrical properties (EPs) in vivo has been a subject of much recent interest. In this work we introduce a method to map tissue EPs from low-flip-angle, zero-echo-time (ZTE) imaging. It is based on a new theoretical formalism that allows calculation of EPs from the product of transmit and receive radio-frequency (RF) field maps. Compared to conventional methods requiring separation of the tr...

  4. Cellulose-Templated Graphene Monoliths with Anisotropic Mechanical, Thermal, and Electrical Properties.

    Science.gov (United States)

    Zhang, Rujing; Chen, Qiao; Zhen, Zhen; Jiang, Xin; Zhong, Minlin; Zhu, Hongwei

    2015-09-02

    Assembling particular building blocks into composites with diverse targeted structures has attracted considerable interest for understanding its new properties and expanding the potential applications. Anisotropic organization is considered as a frequently used targeted architecture and possesses many peculiar properties because of its unusual shapes. Here, we show that anisotropic graphene monoliths (AGMs), three-dimensional architectures of well-aligned graphene sheets obtained by a dip-coating method using cellulose acetate fibers as templates show thermal-insulating, fire-retardant, and anisotropic properties. They exhibit a feature of higher mechanical strength and thermal/electrical conductivities in the axial direction than in the radial direction. Elastic polymer resins are then introduced into the pores of the AGMs to form conductive and flexible composites. The composites, as AGMs, retain the unique anisotropic properties, revealing opposite resistance change under compressions in different directions. The outstanding anisotropic properties of AGMs make them possible to be applied in the fields of thermal insulation, integrated circuits, and electromechanical devices.

  5. A VHF Class E DC-DC Converter with Self-Oscillating Gate Driver

    DEFF Research Database (Denmark)

    Andersen, Toke Meyer; Christensen, Søren K.; Knott, Arnold

    2011-01-01

    This paper describes the analysis and design of a DC-DC converter topology which is operational at frequencies in the Very High Frequency (VHF) band ranging from 30 MHz − 300 MHz. The presented topology, which consists of a class E inverter, class E rectifier, and self-oscillating gate driver, is...

  6. First wind shear observation in PMSE with the tristatic EISCAT VHF radar

    Science.gov (United States)

    Mann, I.; Häggström, I.; Tjulin, A.; Rostami, S.; Anyairo, C. C.; Dalin, P.

    2016-11-01

    The Polar Summer Mesosphere has the lowest temperatures that occur in the entire Earth system. Water ice particles below the optically observable size range participate there in the formation of strong radar echoes (Polar Mesospheric Summer Echoes, PMSE). To study PMSE we carried out observations with the European Incoherent Scatter (EISCAT) VHF and EISCAT UHF radar simultaneously from a site near Tromsø (69.58°N, 19.2272°E) and observed VHF backscattering also with the EISCAT receivers in Kiruna (67.86°N, 20.44°E) and Sodankylä (67.36°N, 26.63°E). This is one of the first tristatic measurements with EISCAT VHF, and we therefore describe the observations and geometry in detail. We present observations made on 26 June 2013 from 7:00 to 13:00 h UT where we found similar PMSE patterns with all three VHF receivers and found signs of wind shear in PMSE. The observations suggest that the PMSE contains sublayers that move in different directions horizontally, and this points to Kelvin-Helmholtz instability possibly playing a role in PMSE formation. We find no signs of PMSE in the UHF data. The electron densities that we derive from observed incoherent scatter at UHF are at PMSE altitudes close to the noise level but possibly indicate reduced electron densities directly above the PMSE.

  7. Properties of zinc-oxide nanoparticles synthesized by electrical-discharge technique in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Tarasenko, Nikolai; Nevar, Alena; Nedelko, Mikhail [Institute of Physics, National Academy of Sciences of Belarus, 68 Nezalezhnasti Ave., 220072 Minsk (Belarus)

    2010-10-15

    The capabilities of a plasma-assisted technique based on electrical discharge in liquids for synthesis of N-doped and In-N codoped ZnO nanocrystals have been analyzed. The synthesis was carried out in a reactor containing aqueous ammonium nitrate solution of 0.001 M concentration. The pulsed-spark discharges between Zn-Zn and Zn-In electrodes have been used with further deposition of the synthesized particles on the silicon substrates. The optical properties, morphology, and composition of the nanoparticles formed were investigated by means of UV-Vis absorption spectroscopy, SEM, EDX, and XRD. As it followed from the XRD patterns the synthesized product was composed of hexagonal ZnO nanocrystals. The positions of the reflection peaks were observed to be varied with the composition of dopants. The influence of doping level on the structural and optical properties of synthesized nanoparticles has been discussed. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  8. Study of microstructure and electrical properties of bulk YBCO prepared by melt textured growth technique

    Energy Technology Data Exchange (ETDEWEB)

    Gonal, M. R.; Krishnan, Madangopal [Glass and Advanced Materials Division, Bhabha Atomic Research Centre, Mumbai, INDIA 400 085 (India); Tewari, R. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai, INDIA 400 085 (India); Tyagi, A. K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai, INDIA 400 085 (India); Gyore, A.; Vajda, I. [Department of Electric Power Engineering, Budapest Univ. of Technology & Economics, Budapest (Hungary)

    2015-06-24

    Bulk YBCO components were prepared using Melt Texture Growth (MTG) technique. Components were fabricated using MTG by addition of Y{sub 2}BaCuO{sub 5} (Y211) and Ag to YBCO, which leads to improved grain size without affecting superconducting properties. Green compacts prepared by cold isostatic pressing were pre-sintered at 930°C before subjecting melt texturing. Cooling rates lower than 1 °C.h{sup −1} was used, in between (peritectic) temperature of about 995 and 1025°C, to obtain large grained components. Microstructure studies in details were carried out by Scanning Electron Microscope (SEM), Electron Probe Micro Analysis (EPMA), Orientation Imaging Microscope (OIM) and TEM correlated with electrical properties like Critical current density (J{sub c})

  9. Calculation of electrical transport properties and electron entanglement in inhomogeneous quantum wires

    Directory of Open Access Journals (Sweden)

    A A Shokri

    2013-10-01

    Full Text Available In this paper, we have investigated the spin-dependent transport properties and electron entanglement in a mesoscopic system, which consists of two semi-infinite leads (as source and drain separated by a typical quantum wire with a given potential. The properties studied include current-voltage characteristic, electrical conductivity, Fano factor and shot noise, and concurrence. The calculations are based on the transfer matrix method within the effective mass approximation. Using the Landauer formalism and transmission coefficient, the dependence of the considered quantities on type of potential well, length and width of potential well, energy of transmitted electron, temperature and the voltage have been theoretically studied. Also, the effect of the above-mentioned factors has been investigated in the nanostructure. The application of the present results may be useful in designing spintronice devices.

  10. Electrical conduction and NO2 gas sensing properties of ZnO nanorods

    Science.gov (United States)

    Şahin, Yasin; Öztürk, Sadullah; Kılınç, Necmettin; Kösemen, Arif; Erkovan, Mustafa; Öztürk, Zafer Ziya

    2014-06-01

    Thermally stimulated current (TSC), photoresponse and gas sensing properties of zinc oxide (ZnO) nanorods were investigated depending on heating rates, illumination and dark aging times with using sandwich type electrode system. Vertically aligned ZnO nanorods were grown on indium tin oxide (ITO) coated glass substrate by hydrothermal process. TSC measurements were performed at different heating rates under constant potential. Photoresponse and gas sensing properties were investigated in dry air ambient at 200 °C. For gas sensing measurements, ZnO nanorods were exposed to NO2 (100 ppb to 1 ppm) in dark and illuminated conditions and the resulting resistance transient was recorded. It was found from dark electrical measurements that the dependence of the dc conductivity on temperature followed Mott's variable range hopping (VRH) model. In addition, response time and recovery times of ZnO nanorods to NO2 gas decreased by exposing to white light.

  11. Investigation of electrical, optical and structural properties of sputtered indium tin oxide thin film

    Science.gov (United States)

    Hasan, Md. Tanvir; Bhalla, Amar; Guo, Ruyan

    2015-09-01

    Transparent and conductive Indium Tin Oxide (ITO) films were grown on borosilicate glass substrate by radio frequency (RF) magnetron sputtering process. The effects of sputtering parameters e.g. substrate temperature and RF power levels on electrical, optical and structural properties were examined. The crystallinity, conductivity and optical transparency of the films were evaluated by X-ray diffraction, four-point probe measurement, laser ellipsometry, and optical spectroscopy. The surface roughness and grain size of the films were also investigated using scanning probe microscopy. This paper reports the non-monotonical dependence of substrate temperature on the nanostructure and phases and the complex impact of RF power levels to the conductivities and the optical properties. The critical role of oxygen partial pressure on the energy bandgaps is also inferred.

  12. Electrical and optical properties of lanthanum oxide-based films prepared by electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Igityan, Arsen; Aghamalyan, Natella; Petrosyan, Silva; Gambaryan, Irina; Badalyan, Georgi; Hovsepyan, Ruben; Kafadaryan, Yevgenia [Institute for Physical Research, NAS of Armenia, Aragatsotn (Armenia)

    2017-06-15

    Lanthanum oxide-based films were deposited on n-Si and quartz substrates using e-beam evaporation method. The XRD patterns demonstrated mixed structure consisting of La{sub 2}O{sub 3} and La(OH){sub 3} phases (referred as La{sub 2}O{sub 3}-OH). Optical and electrical properties of La{sub 2}O{sub 3}-OH films, as well as the effects of the annealing and storage conditions on these properties are described here. It is observed that conductance-voltage characteristics of Al/La{sub 2}O{sub 3}-OH/n-Si devices along with current rectification show negative differential conductance as a result of water molecule redox reaction on the film surface. (orig.)

  13. Electrical conduction and NO{sub 2} gas sensing properties of ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Şahin, Yasin [Council of Forensic Medicine, Bahçelievler, 34196 Istanbul (Turkey); Öztürk, Sadullah, E-mail: sadullahozturk@gyte.edu.tr [Gebze Institute of Technology, Science Faculty, Department of Physics, 41400 Gebze, Kocaeli (Turkey); Kılınç, Necmettin [Gebze Institute of Technology, Science Faculty, Department of Physics, 41400 Gebze, Kocaeli (Turkey); Koc University, Department of Electrical and Electronics Engineering, Sariyer, 34450 Istanbul (Turkey); Kösemen, Arif [Gebze Institute of Technology, Science Faculty, Department of Physics, 41400 Gebze, Kocaeli (Turkey); Mus Alparslan University, Department of Physics, 49100 Mus (Turkey); Erkovan, Mustafa [SAKARYA University, Engineering Faculty, Department of Metallurgical and Materials Engineering, Esentepe Campus, 54187 Sakarya (Turkey); Öztürk, Zafer Ziya [Gebze Institute of Technology, Science Faculty, Department of Physics, 41400 Gebze, Kocaeli (Turkey); TÜBİTAK-Marmara Research Center, Materials Institute, 41470 Gebze, Kocaeli (Turkey)

    2014-06-01

    Thermally stimulated current (TSC), photoresponse and gas sensing properties of zinc oxide (ZnO) nanorods were investigated depending on heating rates, illumination and dark aging times with using sandwich type electrode system. Vertically aligned ZnO nanorods were grown on indium tin oxide (ITO) coated glass substrate by hydrothermal process. TSC measurements were performed at different heating rates under constant potential. Photoresponse and gas sensing properties were investigated in dry air ambient at 200 °C. For gas sensing measurements, ZnO nanorods were exposed to NO{sub 2} (100 ppb to 1 ppm) in dark and illuminated conditions and the resulting resistance transient was recorded. It was found from dark electrical measurements that the dependence of the dc conductivity on temperature followed Mott's variable range hopping (VRH) model. In addition, response time and recovery times of ZnO nanorods to NO{sub 2} gas decreased by exposing to white light.

  14. Enhanced mechanical, thermal, and electric properties of graphene aerogels via supercritical ethanol drying and high-temperature thermal reduction.

    Science.gov (United States)

    Cheng, Yehong; Zhou, Shanbao; Hu, Ping; Zhao, Guangdong; Li, Yongxia; Zhang, Xinghong; Han, Wenbo

    2017-05-03

    Graphene aerogels with high surface areas, ultra-low densities and thermal conductivities have been prepared to exploit their wide applications from pollution adsorption to energy storage, supercapacitor, and thermal insulation. However, the low mechanical properties, poor thermal stability and electric conductivity restrict these aerogels' applications. In this paper, we prepared mechanically strong graphene aerogels with large BET surface areas, low thermal conductivities, high thermal stability and electric conductivities via hydrothermal reduction and supercritical ethanol drying. Annealing at 1500 °C resulted in slightly increased thermal conductivity and further improvement in mechanical properties, oxidation temperature and electric conductivity of the graphene aerogel. The large BET surface areas, together with strong mechanical properties, low thermal conductivities, high thermal stability and electrical conductivities made these graphene aerogels feasible candidates for use in a number of fields covering from batteries to sensors, electrodes, lightweight conductor and insulation materials.

  15. Optical and electrical properties of chemical bath deposited cobalt sulphide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Govindasamy, Geetha [R& D Centre, Bharathiar University, Coimbatore (India); Murugasen, Priya, E-mail: priyamurugasen15@gmail.com [Department of Physics, Saveetha Engineering, Chennai, Tamil Nadu (India); Sagadevan, Suresh [Department of Physics, AMET University, Chennai, Tamil Nadu (India)

    2017-01-15

    Cobalt sulphide (CoS) thin films were synthesized using the Chemical Bath Deposition (CBD) technique. X-ray diffraction (XRD) analysis was used to study the structure and the crystallite size of CoS thin film. Scanning Electron Microscope (SEM) studies reveal the surface morphology of these films. The optical properties of the CoS thin films were determined using UV-Visible absorption spectrum. The optical band gap of the thin films was found to be 1.6 eV. Optical constants such as the refractive index, the extinction coefficient and the electric susceptibility were determined. The dielectric studies were carried out at different frequencies and at different temperatures for the prepared CoS thin films. In addition, the plasma energy of the valence electron, Penn gap or average energy gap, the Fermi energy and electronic polarizability of the thin films were determined. The AC electrical conductivity measurement was also carried out for the thin films. The activation energy was determined by using DC electrical conductivity measurement. (author)

  16. Influence of filler alignment in the mechanical and electrical properties of carbon nanotubes/epoxy nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Felisberto, M. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); INQUIMAE-CONICET-UBA, Pab II Ciudad Universitaria, Buenos Aires 1428 (Argentina); Arias-Duran, A. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Ramos, J.A.; Mondragon, I. [Dep. Ingenieria Quimica y M. Ambiente. Esc. Politecnica. UPV/EHU, Pza. Europa 1, Donostia-San Sebastian 20018 (Spain); Candal, R. [INQUIMAE-CONICET-UBA, Pab II Ciudad Universitaria, Buenos Aires 1428 (Argentina); Escuela de Ciencia y Tecnologia-UNSAM, San Martin, Prov. De Buenos Aires (Argentina); Goyanes, S. [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Rubiolo, G.H., E-mail: rubiolo@cnea.gov.ar [LPyMC, FCEyN-UBA and IFIBA-CONICET, Pab I Ciudad Universitaria, Buenos Aires 1428 (Argentina); Dep. Materiales, Comision Nacional de Energia Atomica (CNEA-CAC), Avda Gral Paz 1499, B1650KNA San Martin (Argentina)

    2012-08-15

    In this work, we report the mechanical and electrical properties of carbon nanotubes/epoxy composites prepared with aligned and randomly oriented nanotubes as filler. The samples are disks of 30 mm in diameter and 3 mm in thickness. To obtain the carbon nanotubes alignment, an external electric field (250 VAC; 50 Hz) was applied through the thickness of the sample during all the cure process. The AC electrical current was measured, during the cure, as a strategy to determine the optimum time in which the alignment reaches the maximum value. DC conductivity measured after the cure shows a percolation threshold in the filler content one order of magnitude smaller for composites with aligned nanotubes than for composites with randomly oriented filler (from 0.06 to 0.5 wt%). In the percolation threshold, the achieved conductivity was 1.4 Multiplication-Sign 10{sup -5} Sm{sup -1}. In both cases, aligned and randomly distributed carbon nanotube composites, the wear resistance increases with the addition of the filler while the Rockwell hardness decreases independently of the nanotubes alignment.

  17. Structural properties and digestibility of pulsed electric field treated waxy rice starch.

    Science.gov (United States)

    Zeng, Feng; Gao, Qun-Yu; Han, Zhong; Zeng, Xin-An; Yu, Shu-Juan

    2016-03-01

    Waxy rice starch was subjected to pulsed electric field (PEF) treatment at intensity of 30, 40 and 50kVcm(-1). The impact of PEF treatment on the granular morphology, molecular weight, semi-crystalline structure, thermal properties, and digestibility were investigated. The micrographs suggested that electric energy could act on the granule structure of starch granule, especially at high intensity of 50kVcm(-1). Gelatinization onset temperature, peak temperature, conclusion temperature and enthalpy value of PEF treated starches were lower than that of native starch. The 9nm lamellar peak of PEF treated starches decreased as revealed by small angle X-ray scattering. The relative crystallinity of treated starches decreased as the increase of electric field intensity. Increased rapidly digestible starch level and decreased slowly digestible starch level was found on PEF treated starches. These results would imply that PEF treatment induced structural changes in waxy rice starch significantly affected its digestibility. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Dependence of electrical properties on thermal temperature in nanocrystalline SnO2 thin films.

    Science.gov (United States)

    Du, Juan; Zhang, HaiJiao; Jiao, Zheng; Wu, Minghong; Shek, Chan-Hung; Wu, C M Lawrence; Lai, Joseph K L; Chen, Zhiwen

    2011-12-01

    Nanocrystalline SnO2 thin films were prepared by pulsed laser deposition techniques on clean glass substrates, and the films were then annealed for 30 min from 50 to 550 degrees C with a step of 50 degrees C, respectively. The investigation of X-ray diffraction confirmed that the various SnO2 thin films were consisted of nanoparticles with average grain size in the range of 23.7-28.9 nm. Root-mean-square surface roughness of the as-prepared SnO2 thin film was measured to be 25.6 nm which decreases to 16.2 nm with thermal annealing. Electrical resistivity and refractive index were measured as a function of annealing temperature, and found to lie between 1.24 to 1.45 momega-cm, and 1.502 to 1.349, respectively. The results indicate that nearly opposite actions to root-mean-square surface roughness and electrical resistivity make a unique performance with thermal annealing temperature. The post annealing shows greater tendency to affect the structural and electrical properties of SnO2 thin films which composed of nanoparticles.

  19. Pyroelectric properties and electrical conductivity in samarium doped BiFeO 3 ceramics

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    Samarium (Sm 3+) doped BiFeO 3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopted a rapid heating as well as cooling during the sintering process. The pyroelectric coefficient increased from 93 to 137 μC/m 2 K as the Sm 3+ doping level increased from 1 mol% to 8 mol%. Temperature dependence of the pyroelectric coefficient showed an abrupt decrease above 80 °C in all samples, which was associated with the increase of electrical conductivity with temperature. This electrical conduction was attributed to oxygen vacancy existing in the samples. An activation energy of ∼0.7 eV for the conduction process was found to be irrespective of the Sm 3+ doping level. On the other hand, the magnetic Néel temperature (T N) decreased with increasing Sm 3+ doping level. On the basis of our results, the effects of Sm doping level on the pyroelectric and electrical properties of the BFO were revealed. © 2011 Elsevier Ltd. All rights reserved.

  20. Effect of multi-structured zinc oxide on the electrical properties of polypropylene insulating materials

    Science.gov (United States)

    Zha, Jun-Wei; Cheng, Qi; Yan, Hong-Da; Li, Wei-Kang; Dang, Zhi-Min

    2017-08-01

    In this paper, polypropylene (PP) nanocomposites filled with ZnO nanoparticles, nanowires and tera-needle-like whiskers were prepared by a melt blending method. The effects of multi-structure ZnO fillers on space charge, breakdown strength and electrical conductive current of PP nanocomposites were investigated. The nanocomposites presented a remarkable suppression on space charge by adding ZnO nanowires, while the addition of ZnO nanoparticles and tera-needle-like whiskers did not effectively suppress the space charge accumulation. The electrical field distortion occurred in the inner of the PP filled with ZnO nanoparticles and tera-needle-like whiskers were about 1.8 kV mm-1 and 3.3 kV mm-1, respectively. Compared with pure PP, the breakdown strength of the PP nanocomposites filled with ZnO nanoparticles and nanowires increased, while they decreased in PP nanocomposites filled with tera-needle-like ZnO whiskers. This work indicated that the improvements on the electrical properties, especially the charge transport and space charge suppression in the nanocomposites were closely related to the different structure of ZnO.

  1. Effect of Organic Tin Compounds on Electric Properties of Model Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Podolak, M.; Engel, G.; Man, D. [Inst. of Physics, Opole Univ., Opole (Poland)

    2006-05-15

    The objective of the present work was to investigate the effect of selected organic tin compounds and potassium chloride (used as a reference substance) on the trans-membrane electric voltage and electric resistance of model membranes, the latter being nitrocellulose filters impregnated with butylene ester of lauric acid. The increasing KCl concentration (in the measurement chambers) caused a rapid rise of the negative trans-membrane voltage, whose value stabilized afterwards. In the case of (C{sub 3}H{sub 7}){sub 3}SnCl an abrupt maximum of the negative voltage was observed followed by a monotonic drop to zero. In the case of highest concentrations of this compound the voltages, after having reached zero, changed their polarization to the opposite. Within the range of small concentrations two slight voltage maxima were observed. Non-ionic tin compounds like (CH{sub 3}){sub 4}Sn and (C{sub 2}H{sub 5}){sub 4}Sn had an insignificant influence on the electric properties of the studied membranes. (orig.)

  2. Electrical transport properties of MoO{sub 3} thin films prepared by laser assisted evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Carreno, L.D.; Pardo, A.; Zuluaga, M.; Torres, J.; Alfonso, J.E. [Group of Materials with Technological Applications, GMAT, Physics Department, Universidad Nacional de Colombia, Bogota (Colombia); Cortes-Bracho, O.L. [Group of Materials with Technological Applications, GMAT, Physics Department, Universidad Nacional de Colombia, Bogota (Colombia); Electronic Engineering Department, Universidad Nacional de Colombia, Bogota (Colombia)

    2007-07-01

    In the present paper the growth of MoO{sub 3} thin films on common glass substrates are described. The films were prepared by evaporation of a MoO{sub 3} target with a CO{sub 2} laser (10.6 {mu}m), operating in the continuous wave mode. The effect of substrate temperature on the crystallographic structure and electrical properties of MoO{sub 3} thin films was studied. The chemical composition of the different species formed on the films surface was obtained by X-ray photoelectron spectroscopy (XPS) and the crystalline structure was studied with X-ray diffraction (XRD). The electrical conductivity of the films was determined using the standard four-points method. Conductivity of the films varied from de 10{sup -9} to 10{sup -5} ({omega}cm){sup -1} in the 300-600 K temperature range. Arrhenius-type plots for the electrical conductivity indicate the presence of at least two different conduction mechanisms. The I-V characteristic curve shows an ohmic behavior only in the 4.5-60 V range. Outside this interval the I-V curve has a behavior described by a power law. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Enhanced Structural, Thermal, and Electrical Properties of Multiwalled Carbon Nanotubes Hybridized with Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yusliza Yusof

    2016-01-01

    Full Text Available The objective of this study is to evaluate the structural, thermal, and electrical properties of multiwalled carbon nanotubes (MWNT hybridized with silver nanoparticles (AgNP obtained via chemical reduction of aqueous silver salt assisted with sodium dodecyl sulphate (SDS as stabilizing agent. Transmission electron microscopy (TEM reveals microstructural analysis of the MWNT-Ag hybrids. The Fourier transform infrared (FTIR spectra prove the interactions between the AgNP and carboxyl groups of the MWNT. Raman spectra reveal that the D- to G-band intensity ratios ID/IG and ID′/IG increase upon the deposition of AgNP onto the surface of the MWNT. Thermogravimetric analysis (TGA shows that the MWNT-Ag hybrids decompose at a much faster rate and the weight loss decreased considerably due to the presence of AgNP. Nonlinearity of current-voltage (I-V curves indicates that electrical transport of pristine MWNT is enhanced when AgNP is induced as charge carriers in the MWNT-Ag hybrids. The threshold voltage Vth value for the MWNT doped with a maximum of 70 vol% of AgNP was substantially reduced by 65% relative to the pristine MWNT. The MWNT-Ag hybrids have a favourable electrical characteristic with a low threshold voltage that shows enhancement mode for field-effect transistor (FET applications.

  4. B1-based SAR reconstruction using contrast source inversion-electric properties tomography (CSI-EPT).

    Science.gov (United States)

    Balidemaj, Edmond; van den Berg, Cornelis A T; van Lier, Astrid L H M W; Nederveen, Aart J; Stalpers, Lukas J A; Crezee, Hans; Remis, Rob F

    2017-02-01

    Specific absorption rate (SAR) assessment is essential for safety purposes during MR acquisition. Online SAR assessment is not trivial and requires, in addition, knowledge of the electric tissue properties and the electric fields in the human anatomy. In this study, the potential of the recently developed CSI-EPT method to reconstruct SAR distributions is investigated. This method is based on integral representations for the electromagnetic field and attempts to reconstruct the tissue parameters and the electric field strength based on [Formula: see text] field data only. Full three-dimensional FDTD simulations using a female pelvis model are used to validate two-dimensional CSI reconstruction results in the central transverse plane of a 3T body coil. Numerical experiments demonstrate that the reconstructed SAR distributions are in good agreement with the SAR distributions as determined via 3D FDTD simulations and show that these distributions can be computed very efficiently in the central transverse plane of a body coil with the two-dimensional approach of CSI-EPT.

  5. Room temperature properties of electrical contacts to alumina composites containing silicon carbide whiskers

    Science.gov (United States)

    Bertram, Brian D.; Gerhardt, Rosario A.

    2009-04-01

    The electrical properties of contacts to hot-pressed alumina composites having variable volume fractions of SiC whiskers (Vw) were investigated with impedance spectroscopy and current-mode atomic force microscopy at room temperature. Three different contact materials were studied: sputtered Pt, sputtered Ag, and conductive Ag paint. Electrode properties were characterized while fresh due to instability over long times (˜100 h). For percolated samples with Vw≥0.10, the electrical response of the electrodes is manifested in the complex impedance plane by a semicircle whose properties are rooted in Schottky barrier blocking at metal contacts to surface whiskers participating in percolated linkages. This process was modeled with a parallel resistor-capacitor (RcCc) equivalent circuit having a relaxation frequency ωc. The dependences of the specific contact resistance (ρs) and specific capacitance (Cs) on Vw were in agreement with the microlevel interpretation above. The three contact materials exhibited significantly different properties, indicating sensitivities to metal work function and metal-whisker interfacing. Both Rc and ωc have exponential dependences on dc bias (Vdc) which are related through the equivalent circuit model. The strengths of these exponentials and the degree of nonlinearity in I-Vdc curves increase with the fraction of Vdc dropping at the electrodes. The dependence of Cs on Vdc also indicated symmetrical Schottky blocking and was used to estimate charge carrier concentration in the whiskers as 1017-1019 cm-3 and a barrier height of 0.2-1.6 eV for sputtered Ag.

  6. Influence of niobium substitution on structural and opto-electrical properties of BNKT piezoelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Vidhi [Electroceramics Research Group, Department of Physics, Birla Institute of Technology, Mesra, Ranchi (India); Ghosh, S.K., E-mail: saritghosh@gmail.com [Electroceramics Research Group, Department of Physics, Birla Institute of Technology, Mesra, Ranchi (India); Hussain, Ali [School of Advanced Materials Engineering, Changwon National University, Gyeong-Nam, 641-773 (Korea, Republic of); Rout, S.K., E-mail: skrout@bitmesra.ac.in [Electroceramics Research Group, Department of Physics, Birla Institute of Technology, Mesra, Ranchi (India)

    2016-07-25

    Lead free niobium modified piezoelectric ceramics Bi{sub 0.5}Na{sub 0.25}K{sub 0.25}Nb{sub x}Ti{sub 1-x}O{sub 3} (BNKT) (x = 0.0, 0.015 and 0.025) compositions along with their structural and opto-electrical properties are investigated. At room temperature Rietveld refinement analysis on x-ray diffraction data revealed the evidence of tetragonal (P4mm) + cubic (Pm3m) mixed phases at 0.015Nb-BNKT composition and at higher niobium concentration it moves towards cubic phase. Presence of local disorder controls the Raman active vibrational modes along with excitation and emission spectra in these materials. The temperature dependence dielectric constant is investigated in the frequency range of 1 kHz–100 kHz. The broadening of dielectric peak and frequency dependence behavior indicated a relaxor property in these materials. Induced A-site vacancies and coexistence of tetragonal-pseudocubic phases lower the depolarization temperature (T{sub d}) with niobium concentration. The structural mix phases have been correlated with the piezoelectric coefficients and the composition x = 0.015 depicts the better piezoelectric properties amongst the studied compositions which is endorsed to the mixed symmetry of tetragonal and cubic phases. - Highlights: • Coexistence of polar and non-polar phases in Nb doped BNKT materials. • Structural instability and lattice disorder controls the opto-electrical properties. • Broadening and shifting of dielectric peaks highlighted the relaxor behavior. • High value of ferroelectric and piezoelectric coefficients at x = 0.015 composition.

  7. Testing VHF/GPS collar design and safety in the study of free-roaming horses.

    Directory of Open Access Journals (Sweden)

    Gail H Collins

    Full Text Available Effective and safe monitoring techniques are needed by U.S. land managers to understand free-roaming horse behavior and habitat use and to aid in making informed management decisions. Global positioning system (GPS and very high frequency (VHF radio collars can be used to provide high spatial and temporal resolution information for detecting free-roaming horse movement. GPS and VHF collars are a common tool used in wildlife management, but have rarely been used for free-roaming horse research and monitoring in the United States. The purpose of this study was to evaluate the design, safety, and detachment device on GPS/VHF collars used to collect free-roaming horse location and movement data. Between 2009 and 2010, 28 domestic and feral horses were marked with commercial and custom designed VHF/GPS collars. Individual horses were evaluated for damage caused by the collar placement, and following initial observations, collar design was modified to reduce the potential for injury. After collar modifications, which included the addition of collar length adjustments to both sides of the collar allowing for better alignment of collar and neck shapes, adding foam padding to the custom collars to replicate the commercial collar foam padding, and repositioning the detachment device to reduce wear along the jowl, we observed little to no evidence of collar wear on horses. Neither custom-built nor commercial collars caused injury to study horses, however, most of the custom-built collars failed to collect data. During the evaluation of collar detachment devices, we had an 89% success rate of collar devices detaching correctly. This study showed that free-roaming horses can be safely marked with GPS and/or VHF collars with minimal risk of injury, and that these collars can be a useful tool for monitoring horses without creating a risk to horse health and wellness.

  8. An analysis on the mid-latitude scintillation and coherence frequency bandwidth using transionospheric VHF signals

    Energy Technology Data Exchange (ETDEWEB)

    Juang, Zhen [Los Alamos National Laboratory; Roussel-dupre, Robert [Los Alamos National Laboratory

    2008-01-01

    An analysis was perfonned on the mid-latitude scintillation and coherence frequency bandwidth (Fcoh) using transionospheric VHF signal data. The data include 1062 events spanning from November 1997 to June 2002. Each event records FORTE satellite received VHF signals from LAPP located at Los Alamos, New Mexico. Fcohs were derived to study scintillation characteristics on diurnal and seasonal variations, as well as changes due to solar and geomagnetic activities. Comparisons to the VHFIUHF coherence frequency bandwidth studies previously reported at equatorial and mid-latitude regions are made using a 4th power frequency dependence relationship. Furthennore, a wideband ionospheric scintillation model, WBMOD, was used to estimate Fcohs and compared with our VHF Fcoh values. Our analysis indicates mid-latitude scintillation characteristics that are not previously revealed. At the VHF bottom frequency range (3035 MHz), distinguished smaller Fcohs are found in time period from sunset to midnight, in wann season from May to August, and in low solar activity years. The effects of geomagnetic storm activity on Fcoh are characterized by a sudden transition at a Kp index of 50-60. Comparisons with median Fcohs estimated from other studies validated our VHF Fcohs for daytime while an order of magnitude larger Fcohs are found for nighttime, implying a time-dependent issue in applying the 4th order power relationship. Furthermore, comparisons with WBMOD-estimated Fcohs indicated generally matched median scintillation level estimates while differences do exist for those events undergoing high geomagnetic stonn activity which may imply underestimates of scintillation level by the WBMOD in the mid-latitude regions.

  9. Molecular Switching in Confined Spaces: Effects of Encapsulating the DHA/VHF Photo-Switch in Cucurbiturils

    DEFF Research Database (Denmark)

    Petersen, Michael Å.; Rasmussen, Brian; Andersen, Nicolaj N.

    2017-01-01

    complexes, the kinetics of the thermal VHF-to-DHA back-reaction is accelerated, while in CB8 inclusion complexes, the kinetics is slowed down as compared to the free photo-switch. The effect of the CB encapsulation of the photo-switch can be effectively canceled by introducing a guest that binds the CB more...... strongly. According to DFT calculations, a stabilization of the reactive s-cis VHF conformer relative to the s-trans VHF appears to be a contributing factor responsible for the accelerated back-reaction when encapsulated in CB7....

  10. Abnormally large magnetospheric electric field on 9 November 2004 ...

    Indian Academy of Sciences (India)

    region recorded by a GPS receiver at Udaipur and attributed the reduced TEC following the storm by weakened electric field due to disturbance dynamo. The space weather event of November 2004 has been studied by Fejer et al. (2007) using Jica- marca VHF radar, magnetometers in Peruvian. (Jicamarca and Piura) and ...

  11. Probing the electrical properties of highly-doped Al:ZnO nanowire ensembles

    KAUST Repository

    Noriega, Rodrigo

    2010-01-01

    The analysis of transparent conducting oxide nanostructures suffers from a lack of high throughput yet quantitatively sensitive set of analytical techniques that can properly assess their electrical properties and serve both as characterization and diagnosis tools. This is addressed by applying a comprehensive set of characterization techniques to study the electrical properties of solution-grown Al-doped ZnO nanowires as a function of composition from 0 to 4 at. % Al:Zn. Carrier mobility and charge density extracted from sensitive optical absorption measurements are in agreement with those extracted from single-wire field-effect transistor devices. The mobility in undoped nanowires is 28 cm2 /V s and decreases to ∼14 cm2 /V s at the highest doping density, though the carrier density remains approximately constant (1020 cm-3) due to limited dopant activation or the creation of charge-compensating defects. Additionally, the local geometry of the Al dopant is studied by nuclear magnetic resonance, showing the occupation of a variety of dopant sites. © 2010 American Institute of Physics.

  12. Crystal structure, electrical properties and electronic band structure of tantalum ditelluride

    CERN Document Server

    Vernes, A; Bensch, W; Heid, W; Naether, C

    1998-01-01

    Motivated by the unexpectedly strong influence of the Te atoms on the structural and bonding properties of the transition metal tellurides, we have performed a detailed study of TaTe sub 2. Experimentally, this comprises a crystal structure determination as well as electrical resistivity measurements. The former analysis leads to an accurate update of the structural data reported in the 1960s, while the latter provides evidence for the mainly electronic character of scattering processes leading to the electrical conductivity. In addition, the electronic properties of TaTe sub 2 have been calculated using the TB-LMTO method. The partial density of states reflects the close connection of the Ta zigzag chains and the Te-Te network. This finding explains the charge transfer in the system in a rather simple way. The orthogonal-orbital character of the bands proved the existence of pi-bonds. The Fermi-surface study supports the interpretation of the experimental resistivity measurements. (author)

  13. Thermal, Mechanical, and Electrical Properties of Graphene Nanoplatelet/Graphene Oxide/ Polyurethane Hybrid Nanocomposite.

    Science.gov (United States)

    Pokharel, Pashupati; Lee, Sang Hyub; Lee, Dai Soo

    2015-01-01

    Hybrid nanocomposites of polyurethane (PU) were prepared by in-situ polymerization of 4,4'- diphenyl methane diisocyanate (MDI) with mixture of graphene oxide (GO) and graphene nanoplatelet (GNP) dispersed in a poly(tetramethylene ether glycol) (PTMEG). Effects of the fillers, GO and GNP, on the thermal, mechanical, and electrical properties of the nanocomposites of PU were investigated. Sonication of the hybrid of GNP and GO with PTMEG enabled effective dispersion of the fillers in the solution than the sonication of GNP alone. The addition of PTMEG in the solution prevented the GNPs from the restacking during the drying process. It was observed that the electrical conductivity and mechanical property of the nanocomposites based on the hybrid of GO and GNP were superior to the nanocomposite based on GNP alone at the same loading of the filler. At the loading of the 3 wt% hybrid filler in PU, we observed the improvement of Young's modulus -200% and the surface resistivity of 10(9.5) ohm/sq without sacrificing the elongation at break.

  14. Structural mosaicity and electrical properties of pyrolytic SnO{sub 2}:F thin films

    Energy Technology Data Exchange (ETDEWEB)

    Garcés, F.A., E-mail: fgarces@intec.unl.edu.ar [Instituto de Desarrollo Tecnológico para la Industria Química, UNL-CONICET, Güemes 3450, S3000GLN Santa Fe (Argentina); Budini, N. [Instituto de Desarrollo Tecnológico para la Industria Química, UNL-CONICET, Güemes 3450, S3000GLN Santa Fe (Argentina); Koropecki, R.R.; Arce, R.D. [Instituto de Desarrollo Tecnológico para la Industria Química, UNL-CONICET, Güemes 3450, S3000GLN Santa Fe (Argentina); Facultad de Ingeniería Química, UNL, Santiago del Estero 2829, S3000AOM Santa Fe (Argentina)

    2013-03-01

    In this work we present structural and electrical properties of SnO{sub 2}:F thin films deposited on glass substrate by the spray pyrolysis technique. The precursors of SnO{sub 2}:F were synthesized by a sol–gel method, starting from a SnCl{sub 4}·5H{sub 2}O/ethanol mixture and using NH{sub 4}F/H{sub 2}O as a dopant. Different properties were observed depending on the deposition time of the films. The structural characteristics of the layers, like crystal size, preferential growth orientation and mosaicity, were studied by X-ray diffraction. These results were compared and correlated with those obtained from electrical measurements, such as carrier density, Hall mobility and resistivity. We have found that for longer deposition times, the mosaicity of the crystallites increases. This process is accompanied by a decrease in the resistivity. - Highlights: ► Tin oxide doped on glass substrate as thin film ► Mosaicity studies enable information about of crystalline domains. ► Increasing time deposition allows modification of resistivity and Hall mobility. ► Increasing the film thickness occur changes in crystalline texture.

  15. Synthesis, optical, and electrical properties of RNA-mediated Ag/PVA nanobiocomposites

    Science.gov (United States)

    Chaudhary, Vidhi; Bhowmick, Anil K.

    2013-03-01

    Synthesis of RNA-templated Ag/PVA nanobiocomposites of controlled morphology was investigated. Surface morphologies of the composites and size distributions of the nanofillers were analyzed by means of field emission scanning electron microscopy. Interfacial interaction between the different components was followed by monitoring the surface plasmon resonance of silver nanoparticles in nanobiocomposites. The band gap approximations suggested semiconducting behavior of the nanobiocomposites with larger band gap than that of the conventional semiconductors. RNA-stabilized Ag/PVA nanobiocomposites revealed the presence of well-dispersed and spherical Ag nanoparticles in PVA matrix with a size distribution of 14-23 nm. IR spectra of the nanobiocomposites demonstrated the complex behavior of RNA with Ag nanoparticles in the polymer matrix due to the presence of noncovalent interactions (electrostatic/van der Waals) between RNA, Ag, and PVA molecules. The effects of the loading of RNA-capped Ag nanoparticles on the electrical properties of PVA were also observed by analyzing I-V characteristics of nanobiocomposites which displayed a large increase (≈89 %) at low concentration relative to neat PVA. The drastic improvement in optical and electrical properties of the nanobiocomposites indicated their promising applications in nanobiotechnology.

  16. Influence of graphene oxide on mechanical, morphological, barrier, and electrical properties of polymer membranes

    Directory of Open Access Journals (Sweden)

    Ali Ammar

    2016-03-01

    Full Text Available This paper expresses a short review of research on the effects of graphene oxide (GO as a nanocomposite element on polymer morphology and resulting property modifications including mechanical, barrier, and electrical conductivity. The effects on mechanical enhancement related to stress measurements in particular are a focus of this review. To first order, varying levels of aggregation of GO in different polymer matrices as a result of their weak inter-particle attractive interactions mainly affect the nanocomposite mechanical properties. The near surface dispersion of GO in polymer/GO nanocomposites can be investigated by studying the surface morphology of these nanocomposites using scanning probe microscopy such as atomic force microscope (AFM and scanning electron microscope (SEM. In the bulk, GO dispersion can be studied by wide-angle X-ray scattering (WAXD by analyzing the diffraction peaks corresponding to the undispersed GO fraction in the polymer matrix. In terms of an application, we review how the hydrophilicity of graphene oxide and its hydrogen bonding potential can enhance water flux of these nanocomposite materials in membrane applications. Likewise, the electrical conductivity of polymer films and bulk polymers can be advantageously enhanced via the percolative dispersion of GO nanoparticles, but this typically requires some additional chemical treatment of the GO nanoparticles to transform it to reduced GO.

  17. Accurate measurement of the localization properties of electric transmission lines using the overlap amplitude

    Science.gov (United States)

    Lazo, Edmundo

    2017-06-01

    We determine the localization properties of classic direct electric transmission lines by means of the overlap amplitude. The amplitude is defined as C i,j ω = 2| I i ω I j ω |, where I i ω is the electric current in the ith cell of the transmission line for the state with frequency ω. This definition is motivated by the concurrence C i,j α = 2| φ i α φ j α |, which is a quantum correlation measure (pairwise entanglement). We distribute the inductances L j according to three non-linear models: (a) the slowly varying potential model; (b) the Aubry-André model and (c) the Soukoulis-Economou model. The results show that the average of the powers of the overlap amplitude ⟨( C i,j ω )2 q ⟩ and its scaling properties may accurately characterize the localization behavior of these non-linear models. Moreover, the overlap amplitude can be used to determine the mobility edge of some non-periodic models.

  18. Effect of argon ion implantation on the electrical and dielectric properties of CR-39

    Energy Technology Data Exchange (ETDEWEB)

    Chawla, Mahak, E-mail: mahak.chawla@gmail.com; Shekhawat, Nidhi; Goyal, Meetika; Gupta, Divya; Sharma, Annu; Aggarwal, Sanjeev [Department of Physics, Kurukshetra University, Kurukshetra - 136119 (India)

    2016-05-23

    The objective of the present work is to study the effect of 130 keV Ar{sup +} ions on the electrical and dielectric properties of CR-39 samples at various doses 5×10{sup 14}, 1×10{sup 15} and 1×10{sup 16} Ar{sup +} cm{sup −2}. Current-Voltage (I-V characteristics) measurements have been used to study the electrical properties of virgin and Ar{sup +} implanted CR-39 specimens. The current has been found to be increased with increasing voltage as well as with increasing ion dose. The dielectric spectroscopy of these specimens has been done in the frequency range of 100 kHz-100 MHz. The dielectric constant has been found to be decreasing whereas dielectric loss factor increases with increasing ion fluence. These kind of behavior observed in the implanted specimens indicate towards the formation of carbonaceous clusters due to the cross linking, chemical bond cleavage, formation of free radicals. The changes observed in the dielectric behavior have been further correlated with the structural changes observed through I-V characteristics.

  19. Fabrication and electrical properties of LiNbO3/ZnO/n-Si heterojunction

    Directory of Open Access Journals (Sweden)

    Lanzhong Hao

    2013-04-01

    Full Text Available Lithium niobate (LiNbO3 or LN ferroelectric films were grown on n-type Si (100 substrates using ZnO as buffer layers by pulse laser deposition technique. The microstructures and electrical properties of the heterojunctions were studied. X-ray diffraction results showed that single (001 orientation for the LN films can be promoted on Si (100 substrates with the buffer effect of the ZnO layers. Due to the ferroelectric polarizations of the LN films, hysteretic characteristics were observed from the capacitance-voltage (C-V curves of the LN/ZnO/n-Si heterojunctions. Obvious photoresponse characteristics were exhibited in the fabricated heterojunction. High performance of the photoresponse of the heterojunction was shown, such as a large ON/OFF ratio, short photoresponse time, steady ON or OFF states, and well reversible. These characteristics make it possible for the heterojunctions to develop multifunctional applications, such as memory devices, eletro-optic devices, and etc. The studied results show that the electrical properties of the heterojunctions were dependent greatly on the thickness of the ZnO buffers and the structural composition of the LN films. The results were discussed in terms of the band diagrams of the LN/ZnO/Si heterojunctions in this work.

  20. Structural and electrical properties of TiO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rao, M. C., E-mail: raomc72@gmail.com; Ravindranadh, K. [Department of Physics, Andhra Loyola College, Vijayawada - 520 008 (India); Shekhawat, M. S. [Department of Physics, Engineering College Bikaner, Bikaner - 334004 (India)

    2016-05-06

    Titanium dioxide (TiO{sub 2}) is traditionally the most widely used white pigment due to its high refractive index. Titanium dioxide (TiO{sub 2}) is traditionally the most widely used white pigment due to its high refractive index. TiO{sub 2} has received considerable attention and it has been used for optical coatings, photo-catalysis agents, gas sensors and solar cells. In this work, nano-structured TiO{sub 2} thin films were grown by pulsed laser deposition (PLD) technique on glass substrates. The prepared thin films were annealed from 400-600 °C in air for a period of 2 hours. Effect of annealing on the structural and electrical properties was studied. X-ray diffraction pattern exhibits peaks correspond to tetragonal anatase phase of TiO{sub 2} and the evaluated average crystallite size of the prepared materials are in the range of 16 to 30 nm. Electrical properties of the prepared samples are analyzed.

  1. Fourth-order relativistic corrections to electrical first-order properties using direct perturbation theory.

    Science.gov (United States)

    Stopkowicz, Stella; Gauss, Jürgen

    2011-05-28

    In this work, we present relativistic corrections to first-order electrical properties obtained using fourth-order direct perturbation theory (DPT4) at the Hartree-Fock level. The considered properties, i.e., dipole moments and electrical-field gradients, have been calculated using numerical differentiation techniques based on a recently reported DPT4 code for energies [S. Stopkowicz and J. Gauss, J. Chem. Phys. 134, 064114 (2011)]. For the hydrogen halides HX, X=F, Cl, Br, I, and At, we study the convergence of the scalar-relativistic contributions by comparing the computed DPT corrections to results from spin-free Dirac-Hartree-Fock calculations. Furthermore, since in the DPT series spin-orbit contributions first appear at fourth order, we investigate their magnitude and judge the performance of the DPT4 treatment by means of Dirac-Hartree-Fock benchmark calculations. Finally, motivated by experimental investigations of the molecules CH(2)FBr, CHF(2)Br, and CH(2)FI, we present theoretical results for their halogen quadrupole-coupling tensors and give recommendations concerning the importance of higher-order scalar-relativistic and spin-orbit corrections. © 2011 American Institute of Physics

  2. Structural and electrical properties of TiO2 thin films

    Science.gov (United States)

    Rao, M. C.; Ravindranadh, K.; Shekhawat, M. S.

    2016-05-01

    Titanium dioxide (TiO2) is traditionally the most widely used white pigment due to its high refractive index. Titanium dioxide (TiO2) is traditionally the most widely used white pigment due to its high refractive index. TiO2 has received considerable attention and it has been used for optical coatings, photo-catalysis agents, gas sensors and solar cells. In this work, nano-structured TiO2 thin films were grown by pulsed laser deposition (PLD) technique on glass substrates. The prepared thin films were annealed from 400-600 °C in air for a period of 2 hours. Effect of annealing on the structural and electrical properties was studied. X-ray diffraction pattern exhibits peaks correspond to tetragonal anatase phase of TiO2 and the evaluated average crystallite size of the prepared materials are in the range of 16 to 30 nm. Electrical properties of the prepared samples are analyzed.

  3. Effect of freezing on electrical properties and quality of thawed chicken breast meat

    Directory of Open Access Journals (Sweden)

    Ran Wei

    2017-04-01

    Full Text Available Objective The objective of this research was to study the electrical properties and quality of frozen-thawed chicken breast meat and to investigate the relationship between these parameters at different times of frozen storage. Methods Thawed samples of chicken breast muscles were evaluated after being kept in frozen storage at −18°C for different periods of time (1, 2, 3, 4, 5, 6, 7, and 8 months. Results The results showed that water-holding capacity (WHC and protein solubility decreased while thiobarbituric acid-reactive substances content increased with increasing storage time. The impedance module of samples decreased during 8-month frozen storage. Pearson correlation coefficients showed that the impedance change ratio (Q value was significantly (p<0.05 related to pH, color, WHC, lipid oxidation and protein solubility, indicating a good relationship between the electrical properties and qualities of frozen-thawed chicken breast meat. Conclusion Impedance measurement has a potential to assess the quality of frozen chicken meat combining with quality indices.

  4. Electrical conductivity, thermal conductivity, and rheological properties of graphene oxide-based nanofluids

    Science.gov (United States)

    Hadadian, Mahboobeh; Goharshadi, Elaheh K.; Youssefi, Abbas

    2014-12-01

    Highly stable graphene oxide (GO)-based nanofluids were simply prepared by dispersing graphite oxide with the average crystallite size of 20 nm, in polar base fluids without using any surfactant. Electrical conductivity, thermal conductivity, and rheological properties of the nanofluids were measured at different mass fractions and various temperatures. An enormous enhancement, 25,678 %, in electrical conductivity of distilled water was observed by loading 0.0006 mass fraction of GO at 25 °C. GO-ethylene glycol nanofluids exhibited a non-Newtonian shear-thinning behavior followed by a shear-independent region. This shear-thinning behavior became more pronounced at higher GO concentrations. The maximum ratio of the viscosity of nanofluid to that of the ethylene glycol as a base fluid was 3.4 for the mass fraction of 0.005 of GO at 20 °C under shear rate of 27.5 s-1. Thermal conductivity enhancement of 30 % was obtained for GO-ethylene glycol nanofluid for mass fraction of 0.07. The measurement of the transport properties of this new kind of nanofluid showed that it could provide an ideal fluid for heat transfer and electronic applications.

  5. Electrical Transport Properties of Ni95Ti5 Catalyzed Multi wall Carbon Nanotubes Film

    Directory of Open Access Journals (Sweden)

    Zishan Husain Khan

    2009-01-01

    Full Text Available Carbon nanotubes (CNTs can be understood as one or more graphite sheets rolled up into a seamless cylinder. CNTs have gained much attention and scientific interest due to their unique properties and potential applications since their discovery in 1991. In the present work, we have deposited Ni95Ti5 film using thermal deposition method. Finally, the Ni95Ti5 catalyzed multi wall carbon nanotubes (MWNTs are grown on silicon substrate using low pressure chemical vapor deposition (LPCVD method and the electrical transport properties of this MWNTs film are studied over a temperature range (284–4K to explain the conduction mechanism. We have suggested two types of conduction mechanism for the entire temperature range. For the temperature region (284–220K, the conduction is due to thermally activated process, whereas the conduction takes place via variable range hopping (VRH for the temperature range of (220–4K. The VRH mechanism changes from three dimensions to two dimensions as we move down to the temperature below 50K. Therefore, the data for the temperature region (220–50K is plotted for three dimensional variable range hopping (3D VRH model and the two dimensional variable range hopping (2D VRH for lower temperature range of (50–4K. These VRH models give a good fit to the experimental data. Using these models, we have calculated various interesting electrical parameters such as activation energy, density of states, hopping distance and hopping energy.

  6. Electrical transport properties of graphene nanowalls grown at low temperature using plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Zhao, Rong; Ahktar, Meysam; Alruqi, Adel; Dharmasena, Ruchira; Jasinski, Jacek B.; Thantirige, Rukshan M.; Sumanasekera, Gamini U.

    2017-05-01

    In this work, we report the electrical transport properties of uniform and vertically oriented graphene (graphene nanowalls) directly synthesized on multiple substrates including glass, Si/SiO2 wafers, and copper foils using radio-frequency plasma enhanced chemical vapor deposition (PECVD) with methane (CH4) as the precursor at relatively low temperatures. The temperature for optimum growth was established with the aid of transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. This approach offers means for low-cost graphene nanowalls growth on an arbitrary substrate with the added advantage of transfer-free device fabrication. The temperature dependence of the electrical transport properties (resistivity and thermopower) were studied in the temperature range, 30-300 K and analyzed with a combination of 2D-variable range hopping (VRH) and thermally activated (TA) conduction mechanisms. An anomalous temperature dependence of the thermopower was observed for all the samples and explained with a combination of a diffusion term having a linear temperature dependence plus a term with an inverse temperature dependence.

  7. Optical and electrical properties of ultra thin metal films and multilayers

    CERN Document Server

    Maaroof, A I

    1994-01-01

    The long term aim of the work described in this thesis was to produce high quality multilayer stacks with very thin layers suitable for near normal incidence optics at short wavelengths. The nucleation and growth of platinum and nickel films, in terms of their structural and electrical properties, has been studied since they are the most promising materials to give smooth and stable ultra-thin layers. Electrical properties offer the possibility of following the nucleation and growth of Pt and Ni films from an early stage through to complete substrate coverage. The in situ d.c. resistance of thin and very thin Pt and Ni films have been measured and monitored during deposition on Corning glass (SiO sub 2) and amorphous carbon (a-C) substrates for different deposition rates and substrate temperatures. It has been shown that the different growth stages of thin films i.e. nucleation, percolation and continuous film formation, can be determined from the plotted curves of the d.c. resistance versus film thickness. C...

  8. A New Method to Improve the Electrical Properties of KNN-based Ceramics: Tailoring Phase Fraction

    KAUST Repository

    Lv, Xiang

    2017-08-18

    Although both the phase type and fraction of multi-phase coexistence can affect the electrical properties of (K,Na)NbO3 (KNN)-based ceramics, effects of phase fraction on their electrical properties were few concerned. In this work, through changing the calcination temperature of CaZrO3 powders, we successfully developed the 0.96K0.5Na0.5Nb0.96Sb0.04O3-0.01CaZrO3-0.03Bi0.5Na0.5HfO3 ceramics containing a wide rhombohedral-tetragonal (R-T) phase coexistence with the variations of T (or R) phase fractions. It was found that higher T phase fraction can warrant a larger piezoelectric constant (d33) and d33 also showed a linear variation with respect to tetragonality ratio (c/a). More importantly, a number of domain patterns were observed due to high T phase fraction and large c/a ratio, greatly benefiting the piezoelectricity. In addition, the improved ferroelectric fatigue behavior and thermal stability were also shown in the ceramics containing high T phase fraction. Therefore, this work can bring a new viewpoint into the physical mechanism of KNN-based ceramics behind R-T phase coexistence.

  9. Effect of annealing temperature on structural, optical and electrical properties of hydrothermal assisted zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Narayanan, Guru Nisha; Sankar Ganesh, R.; Karthigeyan, A., E-mail: karthigeyan.a@ktr.srmuniv.ac.in

    2016-01-01

    Zinc oxide nanorods were grown employing a low cost hydrothermal method on microslide glass substrates pre-coated with ZnO seed layer. The as grown nanorods were annealed in air at 350 °C, 450 °C and 550 °C. The effect of annealing at different temperatures on morphology, structural, optical and electrical properties was investigated using field emission scanning electron microscopic, X-ray diffraction, UV–vis spectral, photoluminescence and electrical studies. The X-ray diffraction pattern of all the samples showed wurtzite structure preferentially oriented along the c-axis (0 0 2) direction. It was found that diameter of the nanorods increased with increasing of annealing temperature. The UV–vis absorption spectra showed a red shift from which it was inferred that the optical bandgap of the material decreases from 3.33 eV to 3.28 eV with increase in annealing temperature. Photoluminescence measurements showed increase in the UV emission intensity with respect to annealing temperature and also produced additional peaks attributed to defects and impurities. Annealing the ZnO nanorod structures at various temperatures evidently showed that the sample annealed at 550 °C acquired the lowest resistivity about 1.62 × 10{sup −4} Ω-cm. - Highlights: • ZnO nanorods were synthesized by hydrothermal method on microslide glass substrates. • Pre-deposited ZnO seeds were used. • Structural, optical and electrical properties of ZnO nanorods were studied. • Crystalline structure of ZnO nanorods was improved with increase in annealing temperature. • Resistivity decrease was observed with increase in the annealing temperature.

  10. Studies of electrical properties of low-resistivity sandstones based on digital rock technology

    Science.gov (United States)

    Yan, Weichao; Sun, Jianmeng; Zhang, Jinyan; Yuan, Weiguo; Zhang, Li; Cui, Likai; Dong, Huaimin

    2018-02-01

    Electrical properties are important parameters to quantitatively calculate water saturation in oil and gas reservoirs by well logging interpretation. It is usual that oil layers show high resistivity responses, while water layers show low-resistivity responses. However, there are low-resistivity oil zones that exist in many oilfields around the world, leading to difficulties for reservoir evaluation. In our research, we used digital rock technology to study different internal and external factors to account for low rock resistivity responses in oil layers. We first constructed three-dimensional digital rock models with five components based on micro-computed tomography technology and x-ray diffraction experimental results, and then oil and water distributions in pores were determined by the pore morphology method. When the resistivity of each component was assigned, rock resistivities were calculated by using the finite element method. We collected 20 sandstone samples to prove the effectiveness of our numerical simulation methods. Based on the control variate method, we studied the effects of different factors on the resistivity indexes and rock resistivities. After sensitivity analyses, we found the main factors which caused low rock resistivities in oil layers. For unfractured rocks, influential factors arranged in descending order of importance were porosity, clay content, temperature, water salinity, heavy mineral, clay type and wettability. In addition, we found that the resistivity index could not provide enough information to identify a low-resistivity oil zone by using laboratory rock–electric experimental results. These results can not only expand our understandings of the electrical properties of low-resistivity rocks from oil layers, but also help identify low-resistivity oil zones better.

  11. Multiwall carbon nanotube-filled natural rubber: Electrical and mechanical properties

    Directory of Open Access Journals (Sweden)

    L. Bokobza

    2012-03-01

    Full Text Available The influence of multiwall carbon nanotube (MWNTs contents on electrical and mechanical properties of MWNTs-reinforced natural rubber (NR composites is studied. The volume resistivity of the composites decreases with increasing the MWNTs content and the electrical percolation threshold is reached at less than 1 phr of MWNTs (phr = parts of filler by weight per hundred parts of rubber. This is caused by the formation of conductive chains in the composites. Electrical measurements under uniaxial deformation of a composite carried out at a filler loading above the percolation threshold, indicate a gradual disconnection of the conducting network with the bulk deformation. The drop in the storage modulus G' with the shear strain amplitude (Payne effect is also attributed to a breakdown of the filler network. Considerable improvement in the stiffness is obtained upon incorporation of MWNTs in the polymer matrix but the main factor for reinforcement of NR by MWNTs appears to be their high aspect ratio rather than strong interfacial interaction with rubber. The tensile strength and the elongation at break of the composites are reduced with regard to the unfilled sample. This is probably due to the presence of some agglomerates that increase with the nanotube content. This hypothesis is confirmed by a cyclic loading of the composites where it is seen that the deformation at break occurs at a much higher level of strain in the second stretch than in the first one. The overall significant property improvements are the result of a better nanotube dispersion attributed to the combined use of tip sonication and cyclohexane as dispersion aids during composite processing.

  12. Effect of Li doping on the electric and pyroelectric properties of ZnO thin films

    Science.gov (United States)

    Trinca, L. M.; Galca, A. C.; Boni, A. G.; Botea, M.; Pintilie, L.

    2018-01-01

    Un-doped ZnO (UDZO) and Li-doped ZnO (LZO) polycrystalline thin films were grown on platinized silicon by pulsed laser deposition (PLD). The electrical properties were investigated on as-grown and annealed UDZO and LZO films with capacitor configuration, using top and bottom platinum electrodes. In the case of the as-grown films it was found that the introduction of Li increases the resistivity of ZnO and induces butterfly shape in the C-V characteristic, suggesting ferroelectric-like behavior in LZO films. The properties of LZO samples does not significantly changes after thermal annealing while the properties of UDZO samples show significant changes upon annealing, manifested in a butterfly shape of the C-V characteristic and resistive-like switching. However, the butterfly shape disappears if long delay time is used in the C-V measurement, the characteristic remaining non-linear. Pyroelectric signal could be measured only on annealed films. Comparing the UDZO results with those obtained in the case of Li:ZnO, it was found that the pyroelectric properties are considerably enhanced by Li doping, leading to pyroelectric signal with about one order of magnitude larger at low modulation frequencies than for un-doped samples. Although the results of this study hint towards a ferroelectric-like behavior of Li doped ZnO, the presence of real ferroelectricity in this material remains controversial.

  13. Optical and Electrical Properties of III-Nitrides and Related Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Hongxing [Texas Tech Univ., Lubbock, TX (United States); Lin, Jingyu [Texas Tech Univ., Lubbock, TX (United States)

    2016-01-22

    Among the members of the III-nitride material system, boron-nitride (BN) is the least studied and understood. Its extraordinary physical properties, such as ultra-high chemical stability, thermal conductivity, electrical resistivity, band gap (Eg ~ 6 eV), and optical absorption near the band gap make hexagonal BN (h-BN) the material of choice for emerging applications such as deep ultraviolet (DUV) optoelectronic devices. Moreover, h-BN has a close lattice match to graphene and is the most suitable substrate and dielectric/separation layer for graphene electronics and optoelectronics. Similar to graphene, low dimensional h-BN is expected to possess rich new physics. Other potential applications include super-capacitors and electron emitters. However, our knowledge concerning the semiconducting properties of h-BN is very scarce. The project aims to extend our studies to the “newest” family member of the III-nitride material system, h-BN, and to address issues that have not yet been explored but are expected to profoundly influence our understanding on its fundamental properties and device applications. During the supporting period, we have improved the growth processes of h-BN epilayers by metal organic chemical vapor deposition (MOCVD), investigated the fundamental material properties, and identified several unique features of h-BN as well as critical issues that remain to be addressed.

  14. Phase transition and electrical properties of lanthanum-modified sodium bismuth titanate

    Energy Technology Data Exchange (ETDEWEB)

    Barick, B.K. [Department of Physics, National Institute of Technology, Rourkela 769008 (India); Choudhary, R.N.P. [Department of Physics, Institute of Technical Education and Research, SOA University, Bhubaneswar 751030 (India); Pradhan, Dillip K., E-mail: dillip.pradhan79@gmail.com [Department of Physics, National Institute of Technology, Rourkela 769008 (India)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Synthesis of lanthanum modified sodium bismuth titanate by solid-state reaction route. Black-Right-Pointing-Pointer Three distinct phase transitions are observed from variation of dielectric constant with temperature. Black-Right-Pointing-Pointer Dielectric constant decrease and diffusivity of phase transition increases with increase in lanthanum content. Black-Right-Pointing-Pointer Impedance spectroscopy suggests the contribution of both grain and grain boundary to the electrical response of the material. - Abstract: Structural, microstructural and electrical properties of lanthanum-modified sodium bismuth titanate (Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}) (NBT) ceramics were investigated. X-ray diffraction (XRD) analysis of the prepared materials confirmed the formation of the compounds with rhombohedral crystal system. The nature of scanning electron micrographs of the compounds showed (i) the uniform distribution of grains on the sample surface with high density and (ii) reduction of grain size on La substitution at the (Na-Bi) sites of NBT. Detailed studies of dielectric and impedance properties of the materials, carried out in the frequency range of 10{sup 2}-10{sup 6} Hz at different temperatures (room temperature to 500 Degree-Sign C), have provided many interesting properties. The dielectric constant at transition temperature was found to be decreased with increase of broadening of the dielectric peak on increasing La content in the sample. The transition temperature (T{sub m}) shifted to higher temperature side on addition of La (up to 6%), whereas the reverse trend was observed for higher concentration of La (i.e. 8%). The depolarization temperature (T{sub d}) of La-modified NBT compounds was found to be smaller than that of pure NBT. The tangent loss was also found to be decreased on the incorporation of La into NBT. The ac conductivity of the La-modified NBT obeyed the double power law behavior. Complex impedance

  15. Understanding the low temperature electrical properties of nanocrystalline tin oxide for gas sensor applications

    Science.gov (United States)

    Drake, Christina Hartsell

    Nanocrystalline metal/metal oxide is an important class of transparent and electronic materials due to its potential use in many applications, including gas sensors. At the nanoscale, many of the phenomena observed that give nanocrystalline semiconducting oxide enhanced performance as a gas sensor material over other conventional engineering materials is still poorly understood. This study is aimed at understanding the low temperature electrical and chemical properties of nanocrystalline SnO2 that makes it suitable for room temperature gas detectors. Studies were carried out in order to understand how various synthesis methods affect the surfaces on the nano-oxides, interactions of a target gas (in this study hydrogen) with different surface species, and changes in the electrical properties as a function of dopants and grain size. A correlation between the surface reactions and the electrical response of doped nanocrystalline metal-oxide-semiconductors exposed to a reducing gas is established using Fourier Transform Infrared (FTIR) Spectroscopy attached to a specially built custom designed catalytic cell. First principle calculations of oxygen vacancy concentrations from absorbance spectra are presented. FTIR is used for effectively screening of these nanostructures for gas sensing applications. The effect of processing temperature on the microstructural evolution and on the electronic properties of nanocrystalline trivalent doped-SnO 2 is also presented. This study includes the effect of dopants (In and Ce) on the growth of nano-SnO2, as well as their effects on the electronic properties and gas sensor behavior of the nanomaterial at room temperature. Band bending affects are also investigated for this system and are related to enhanced low temperature gas sensing. The role and importance of oxygen vacancies in the electronic and chemical behavior of surface modified nanocrystalline SnO2 are explored in this study. A generalized explanation for the low temperature

  16. The homeobox transcription factor Even-skipped regulates acquisition of electrical properties in Drosophila neurons

    Directory of Open Access Journals (Sweden)

    Brand Andrea H

    2006-11-01

    Full Text Available Abstract Background While developmental processes such as axon pathfinding and synapse formation have been characterized in detail, comparatively less is known of the intrinsic developmental mechanisms that regulate transcription of ion channel genes in embryonic neurons. Early decisions, including motoneuron axon targeting, are orchestrated by a cohort of transcription factors that act together in a combinatorial manner. These transcription factors include Even-skipped (Eve, islet and Lim3. The perdurance of these factors in late embryonic neurons is, however, indicative that they might also regulate additional aspects of neuron development, including the acquisition of electrical properties. Results To test the hypothesis that a combinatorial code transcription factor is also able to influence the acquisition of electrical properties in embryonic neurons we utilized the molecular genetics of Drosophila to manipulate the expression of Eve in identified motoneurons. We show that increasing expression of this transcription factor, in two Eve-positive motoneurons (aCC and RP2, is indeed sufficient to affect the electrical properties of these neurons in early first instar larvae. Specifically, we observed a decrease in both the fast K+ conductance (IKfast and amplitude of quantal cholinergic synaptic input. We used charybdotoxin to pharmacologically separate the individual components of IKfast to show that increased Eve specifically down regulates the Slowpoke (a BK Ca2+-gated potassium channel, but not Shal, component of this current. Identification of target genes for Eve, using DNA adenine methyltransferase identification, revealed strong binding sites in slowpoke and nAcRα-96Aa (a nicotinic acetylcholine receptor subunit. Verification using real-time PCR shows that pan-neuronal expression of eve is sufficient to repress transcripts for both slo and nAcRα-96Aa. Conclusion Taken together, our findings demonstrate, for the first time, that Eve

  17. Electrical, optical and microstructural properties of transparent conducting GZO thin films deposited by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    You, Z.Z., E-mail: zzyyyzz@163.com [College of Electronic Information Engineering, South-Central University for Nationalities (SCUN), Wuhan 430074 (China); Hua, G.J. [Center of Computing and Experimenting, South-Central University for Nationalities (SCUN), Wuhan 430074 (China)

    2012-07-25

    Graphical abstract: Gallium-doped zinc oxide (GZO) thin films were grown by magnetron sputtering. The electrical, optical and microstructural properties of the thin films were systematically studied. Highlights: Black-Right-Pointing-Pointer Thin films of transparent conducting gallium-doped zinc oxide were grown by magnetron sputtering technique at various substrate temperatures. Black-Right-Pointing-Pointer The microstructural properties of the films were investigated by X-ray diffraction (XRD). Black-Right-Pointing-Pointer The chemical state and elemental composition of the films were analyzed by X-ray photoelectron spectroscopy (XPS). Black-Right-Pointing-Pointer The optical properties of the films were studied by optical characterization methods. Black-Right-Pointing-Pointer The optoelectrical properties of the films were quantified by means of the figure of merit. - Abstract: Thin films of transparent conducting gallium-doped zinc oxide (GZO) were deposited by magnetron sputtering technique onto glass substrates. The films were characterized by various methods to understand their microstructural, optical and electrical characteristics. The effects of substrate temperature on the physical properties of the films were investigated. The results show that the GZO films are polycrystalline in nature having a hexagonal wurtzite type crystal structure with a preferred grain orientation in the (0 0 2) direction. The substrate temperature significantly affects the crystal structure and optoelectrical properties of the films. The GZO film grown at the substrate temperature of 670 K has the largest crystal grain, the lowest resistivity and the highest figure of merit. Meanwhile, the optical constants, dielectric function and dissipation factor of the films were determined using the methods of Manifacier and Swanepoel. The dispersion behavior of the refractive index was studied in terms of the single-oscillator Wemple-DiDomenico (W-D) model, and the oscillator parameters

  18. Size effects in electrical and magnetic properties of quasi-one-dimensional tin wires in asbestos

    Science.gov (United States)

    Chernyaev, A. V.; Shamshur, D. V.; Fokin, A. V.; Kalmykov, A. E.; Kumzerov, Yu. A.; Sorokin, L. M.; Parfen'ev, R. V.; Lashkul, A.

    2016-03-01

    Bulk composites have been prepared based on one-dimensional fibers of natural chrisothil-asbestos with various internal diameters ( d = 6-2.5 nm) filled with tin. The electrical and magnetic properties of quasi-one-dimensional Sn wires have been studied at low temperatures. The electrical properties have been measured at T = 300 K at a pressure P = 10 kbar. It has been found that the superconducting (SC) characteristics of the nanocomposites (critical temperature T c and critical magnetic field H c) increase as the Sn filament diameter decreases. The temperature spreading of the resistive SC transition also increases as the Sn filament diameter decreases, which is explained by the SC order parameter fluctuations. The size effects (the increase in critical temperature T c and transition width Δ T c) in Sn nanofilaments are well described by the independent Aslamazov-Larkin and Langer-Ambegaokara fluctuation theories, which makes it possible to find the dependence of T c of the diffuse SC transition on the nanowire diameter. Using the temperature and magnetic-field dependences of the magnetic moment M( T, H), it has been found that the superconductor-normal metal phase diagram of the Sn-asbestos nanocomposite has a wider region of the SC state in T and H as compared to the data for bulk Sn. The magnetic properties of chrisotil-asbestos fibers unfilled with Sn have been studied. It has been found that the Curie law is fulfilled and that the superparamagnetism is absent in such samples. The obtained results indicate the absence of magnetically ordered impurities (magnetite) in the chrisotil-asbestos matrix, which allowed one to not consider the problem of the interaction of the magnetic subsystem of the asbestos matrix and the superconducting subsystem of Sn nanowires.

  19. Relationship between morphology and electrical properties in PP/MWCNT composites: Processing-induced anisotropic percolation threshold

    Energy Technology Data Exchange (ETDEWEB)

    Cesano, F., E-mail: federico.cesano@unito.it [Department of Chemistry, NIS (Nanostructured Interfaces and Surfaces) Interdepartmental Centre and INSTM Centro di Riferimento, University of Torino, Via P. Giuria, 7, 10125 Torino (Italy); Zaccone, M. [Proplast, Strada Comunale Savonesa 9, 15057 Rivalta Scrivia, AL (Italy); ECNP, Strada Comunale Savonesa 9, 15057 Rivalta Scrivia, AL (Italy); Armentano, I. [Materials Engineering Center, UdR INSTM, University of Perugia, Str. Pentima 4, 05100 Terni (Italy); Cravanzola, S.; Muscuso, L. [Department of Chemistry, NIS (Nanostructured Interfaces and Surfaces) Interdepartmental Centre and INSTM Centro di Riferimento, University of Torino, Via P. Giuria, 7, 10125 Torino (Italy); Torre, L. [Materials Engineering Center, UdR INSTM, University of Perugia, Str. Pentima 4, 05100 Terni (Italy); Kenny, J.M. [ECNP, Strada Comunale Savonesa 9, 15057 Rivalta Scrivia, AL (Italy); Materials Engineering Center, UdR INSTM, University of Perugia, Str. Pentima 4, 05100 Terni (Italy); Monti, M. [Proplast, Strada Comunale Savonesa 9, 15057 Rivalta Scrivia, AL (Italy); Scarano, D. [Department of Chemistry, NIS (Nanostructured Interfaces and Surfaces) Interdepartmental Centre and INSTM Centro di Riferimento, University of Torino, Via P. Giuria, 7, 10125 Torino (Italy)

    2016-09-01

    Multi-walled carbon nanotubes (MWCNTs)/polypropylene composites were prepared by melt-mixing, by varying the MWCNT content from 1 to 7 wt%, and samples were manufactured by injection moulding technique. DC electrical characterization was performed by the two-probe method in the three main directions: longitudinal and transversal to the flux of the material during the mould filling, and in the through-thickness direction. Moreover, a dedicated setup was adopted to measure the electrical resistance at different depths of the specimen cross-sectional areas. Two different electrical percolation thresholds, calculated at about 2 wt% and 3 wt% of MWCNTs (longitudinally/transversely to the mould filling flux and in the through-thickness directions, respectively), were found. In order to investigate the role of the structure/morphology of the composites on the electrical properties, samples have been cryofractured, chemically etched and characterized by means of scanning electron microscopy. As a result, the observed anisotropic electrical behaviour was associated with the different network morphology, which was detected in the cross-sectional area, caused by the injection moulding process. Based on the observed through-thickness electrical behaviour, a phenomenological DC conduction model has been developed, describing the sample as a multilayer system, being the external layers (skin) less conductive than the internal region (core). This model, combined with the bulk electrical tests, can be considered as a valuable mathematical tool to foresee the electrical behaviour of MWCNT-based composites for designing new industrial injection-moulded components. - Highlights: • (1–7 wt%) MWCNTs/polypropylene composites are made by injection moulding technique. • The mould temperature is affecting the anisotropic electrical properties. • The anisotropic properties are connected with CNTs dispersion/aggregation. • External layers (skin) are less conductive than the

  20. Electrical properties of III-Nitride LEDs: Recombination-based injection model and theoretical limits to electrical efficiency and electroluminescent cooling

    Energy Technology Data Exchange (ETDEWEB)

    David, Aurelien, E-mail: adavid@soraa.com; Hurni, Christophe A.; Young, Nathan G.; Craven, Michael D. [Soraa Inc., 6500 Kaiser Dr., Fremont, California 94555 (United States)

    2016-08-22

    The current-voltage characteristic and ideality factor of III-Nitride quantum well light-emitting diodes (LEDs) grown on bulk GaN substrates are investigated. At operating temperature, these electrical properties exhibit a simple behavior. A model in which only active-region recombinations have a contribution to the LED current is found to account for experimental results. The limit of LED electrical efficiency is discussed based on the model and on thermodynamic arguments, and implications for electroluminescent cooling are examined.