WorldWideScience

Sample records for technologically important semiconducting

  1. Concise encyclopedia of semiconducting materials and related technologies

    CERN Document Server

    Mahajan, S M

    1992-01-01

    The development of electronic materials and particularly advances in semiconductor technology have played a central role in the electronics revolution by allowing the production of increasingly cheap and powerful computing equipment and advanced telecommunications devices. This Concise Encyclopedia, which incorporates relevant articles from the acclaimed Encyclopedia of Materials Science and Engineering as well as newly commissioned articles, emphasizes the materials aspects of semiconductors and the technologies important in solid-state electronics. Growth of bulk crystals and epitaxial layer

  2. Semiconducting polymers: the Third Generation.

    Science.gov (United States)

    Heeger, Alan J

    2010-07-01

    There has been remarkable progress in the science and technology of semiconducting polymers during the past decade. The field has evolved from the early work on polyacetylene (the First Generation material) to a proper focus on soluble and processible polymers and co-polymers. The soluble poly(alkylthiophenes) and the soluble PPVs are perhaps the most important examples of the Second Generation of semiconducting polymers. Third Generation semiconducting polymers have more complex molecular structures with more atoms in the repeat unit. Important examples include the highly ordered and crystalline PDTTT and the ever-growing class of donor-acceptor co-polymers that has emerged in the past few years. Examples of the latter include the bithiophene-acceptor co-polymers pioneered by Konarka and the polycarbazole-acceptor co-polymers pioneered by Leclerc and colleagues. In this tutorial review, I will summarize progress in the basic physics, the materials science, the device science and the device performance with emphasis on the following recent studies of Third Generation semiconducting polymers: stable semiconducting polymers; self-assembly of bulk heterojunction (BHJ) materials by spontaneous phase separation; bulk heterojunction solar cells with internal quantum efficiency approaching 100%; high detectivity photodetectors fabricated from BHJ materials.

  3. PREFACE: Semiconducting oxides Semiconducting oxides

    Science.gov (United States)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

  4. Intermetallic semiconducting films

    CERN Document Server

    Wieder, H H

    1970-01-01

    Intermetallic Semiconducting Films introduces the physics and technology of AшВv compound films. This material is a type of a polycrystalline semiconductor that is used for galvanomagnetic device applications. Such material has a high electron mobility that is ideal for generators and magnetoresistors. The book discusses the available references on the preparation and identification of the material. An assessment of its device applications and other possible use is also enumerated. The book describes the structures and physical parts of different films. A section of the book covers the three t

  5. Resistance Allocation Plan of Semiconducting Silicone Rubber Applied to Insulators for Anti-icing

    Institute of Scientific and Technical Information of China (English)

    WEI Xiaoxing; JIA Zhidong; SUN Zhenting; GUAN Zhicheng; ZHAO Yuming

    2012-01-01

    The anti-icing and de-icing methods of insulator strings are still under laboratory studies while many technologies are applied in operation to overhead conductors. The anti-icing method using semiconducting silicone rubber coating applied to the bottom side of the insulators could get good results in a climate chamber. However, the resistance of the coating is an important factor influencing the anti-icing performance of the coated insulators. Thus the coating resistance should be determined. A heating analytical method of insulators with semiconducting silicone rubber (SIR) is proposed.

  6. Low Dimension Semiconducting Composite Nanomaterials

    Institute of Scientific and Technical Information of China (English)

    WANG Mang; CHEN Hong-zheng; SUN Jing-zhi

    2004-01-01

    Recently, low dimension nanostructures have gained considerable attention due to their technological potential as unique types of nanoscale building blocks for future optoelectronic devices and systems. Semiconducting composite nanomaterials, which can combine the advantages of two or more components, have been the focus in the area of nanomaterials synthesis and device application.In this paper, we report our work on the preparation of composite nanomaterials based on CNTs.CNTs were coated by organic or inorganic species via novel and facile methods (Fig. 1 and Fig.2).These functional CNTs based composites show eminent prospects and opportunities for new applications in a wide variation of areas.

  7. Semiconducting-polymer photonic devices

    Science.gov (United States)

    Ho, Peter; Tessler, Nir; Friend, Richard H.

    2001-10-01

    The last decade has seen tremendous advances in the field of semiconducting-polymer optoelectronics as a result of a concerted chemistry, physics and engineering effort. For example, ink-jet-printed full-color active-matrix thin-film display prototypes with semiconducting polymers as the active layers have already been demonstrated. The key advantages of this technology lie in its full-color capability, scalability to both large-area and micro- displays, as well as low-cost associated with simplicity and solution processability. In a number of related inorganic device technologies, the control of optical properties using photonic structures has ben crucial to the performance of the devices. In principle, polymer devices can also benefit from such control if appropriate polymer optical building blocks that retain the processing advantages can be found. Here we will show that the refractive index of poly(p- phenylenevinuylene) (PPV) can be tuned over remarkable ranges from 1.6 to 2.7 at 550-nm wavelength by dispersing 50-angstrom-diameter silica nanoparticles into its matrix. This is achieved without incurring significant optical scattering losses. Using these semiconducting-polymer composites, we have demonstrated efficient distributed Bragg reflectors in the green spectral region from relatively few periods of quarterwave stacks of the high- and low-index materials. Controlled chemical doping of these photonic structures fabricated polymer microcavity light-emitting diodes in which current is injected through the polymer DBR with adequate confinement of photons and electron-hole pairs. We have also fabricated photo pumped all-polymer microcavity structures.

  8. Semiconducting polymeric materials

    NARCIS (Netherlands)

    de Boer, Bert; Facchetti, Antonio

    2008-01-01

    (Semi)conducting polymers with a pi-conjugated (hetero)aromatic backbone are capable of transporting charge and interact efficiently with light enabling their utilization in a variety of opto-electronic devices. In this report and in the additional papers of this special issue, several classes of pi

  9. Semiconducting polymeric materials

    NARCIS (Netherlands)

    de Boer, Bert; Facchetti, Antonio

    2008-01-01

    (Semi)conducting polymers with a pi-conjugated (hetero)aromatic backbone are capable of transporting charge and interact efficiently with light enabling their utilization in a variety of opto-electronic devices. In this report and in the additional papers of this special issue, several classes of

  10. Surface physics of semiconducting nanowires

    Science.gov (United States)

    Amato, Michele; Rurali, Riccardo

    2016-02-01

    Semiconducting nanowires (NWs) are firm candidates for novel nanoelectronic devices and a fruitful playground for fundamental physics. Ultra-thin nanowires, with diameters below 10 nm, present exotic quantum effects due to the confinement of the wave functions, e.g. widening of the electronic band-gap, deepening of the dopant states. However, although several reports of sub-10 nm wires exist to date, the most common NWs have diameters that range from 20 to 200 nm, where these quantum effects are absent or play a very minor role. Yet, the research activity on this field is very intense and these materials still promise to provide an important paradigm shift for the design of emerging electronic devices and different kinds of applications. A legitimate question is then: what makes a nanowire different from bulk systems? The answer is certainly the large surface-to-volume ratio. In this article we discuss the most salient features of surface physics and chemistry in group-IV semiconducting nanowires, focusing mostly on Si NWs. First we review the state-of-the-art of NW growth to achieve a smooth and controlled surface morphology. Next we discuss the importance of a proper surface passivation and its role on the NW electronic properties. Finally, stressing the importance of a large surface-to-volume ratio and emphasizing the fact that in a NW the surface is where most of the action takes place, we discuss molecular sensing and molecular doping.

  11. Doping of Semiconducting Atomic Chains

    Science.gov (United States)

    Toshishige, Yamada; Kutler, Paul (Technical Monitor)

    1997-01-01

    Due to the rapid progress in atom manipulation technology, atomic chain electronics would not be a dream, where foreign atoms are placed on a substrate to form a chain, and its electronic properties are designed by controlling the lattice constant d. It has been shown theoretically that a Si atomic chain is metallic regardless of d and that a Mg atomic chain is semiconducting or insulating with a band gap modified with d. For electronic applications, it is essential to establish a method to dope a semiconducting chain, which is to control the Fermi energy position without altering the original band structure. If we replace some of the chain atoms with dopant atoms randomly, the electrons will see random potential along the chain and will be localized strongly in space (Anderson localization). However, if we replace periodically, although the electrons can spread over the chain, there will generally appear new bands and band gaps reflecting the new periodicity of dopant atoms. This will change the original band structure significantly. In order to overcome this dilemma, we may place a dopant atom beside the chain at every N lattice periods (N > 1). Because of the periodic arrangement of dopant atoms, we can avoid the unwanted Anderson localization. Moreover, since the dopant atoms do not constitute the chain, the overlap interaction between them is minimized, and the band structure modification can be made smallest. Some tight-binding results will be discussed to demonstrate the present idea.

  12. Semiconducting polymer LEDs

    Directory of Open Access Journals (Sweden)

    David Braun

    2002-06-01

    The field of semiconducting polymers has its root in the 1977 discovery of the semiconducting properties of polyacetylene1. This breakthrough earned Alan Heeger, Alan MacDiarmid, and Hideki Shirakawa the 2000 Nobel Prize in Chemistry for ‘the discovery and development of conductive polymers’2–5. Other review articles capture how more than two decades of developments in the physical and chemical understanding of these novel materials has led to new device applications as active and passive electronic and optoelectronic devices ranging from diodes and transistors to polymer LEDs, photodiodes, lasers, and solar cells6–11. Much interest in plastic devices derives from the opportunities to use clever control of polymer structure combined with relatively economical polymer synthesis and processing techniques to obtain simultaneous control over electronic, optical, chemical, and mechanical features5. This article focuses on the advances leading to polymer LEDs12–14.

  13. Nano semiconducting materials

    CERN Document Server

    Saravanan, R

    2016-01-01

    The main focus of the present book is the characterization of a number of nano-semiconducting materials, using such techniques as powder X-ray diffraction, UV-visible spectrophotometry, Raman spectrometry, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. The materials studied include ZnS, TiO2, NiO, Ga doped ZnO, Mn doped SnO2, Mn doped CeO2 and Mn doped ZrO2.

  14. Educators' Perceived Importance of Web 2.0 Technology Applications

    Science.gov (United States)

    Pritchett, Christal C.; Wohleb, Elisha C.; Pritchett, Christopher G.

    2013-01-01

    This research study was designed to examine the degree of perceived importance of interactive technology applications among various groups of certified educators; the degree to which education professionals utilized interactive online technology applications and to determine if there was a significant difference between the different groups based…

  15. Educators' Perceived Importance of Web 2.0 Technology Applications

    Science.gov (United States)

    Pritchett, Christal C.; Wohleb, Elisha C.; Pritchett, Christopher G.

    2013-01-01

    This research study was designed to examine the degree of perceived importance of interactive technology applications among various groups of certified educators; the degree to which education professionals utilized interactive online technology applications and to determine if there was a significant difference between the different groups based…

  16. The Strategic Importance of Information Technology in Community Colleges

    Science.gov (United States)

    Lu, Romy Emaas

    2010-01-01

    In 2003, Nicholas Carr published in "Harvard Business Review" his article "IT Doesn't Matter," which rekindled the debate on the strategic importance of information technology (IT). Chief Information Officers (CIOs) of community colleges are now faced with the challenge of seeking the best technology for their institutions. The…

  17. The Strategic Importance of Information Technology in Community Colleges

    Science.gov (United States)

    Lu, Romy Emaas

    2010-01-01

    In 2003, Nicholas Carr published in "Harvard Business Review" his article "IT Doesn't Matter," which rekindled the debate on the strategic importance of information technology (IT). Chief Information Officers (CIOs) of community colleges are now faced with the challenge of seeking the best technology for their institutions. The…

  18. High-mobility ultrathin semiconducting films prepared by spin coating.

    Science.gov (United States)

    Mitzi, David B; Kosbar, Laura L; Murray, Conal E; Copel, Matthew; Afzali, Ali

    2004-03-18

    The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (approximately 50 A), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS(2-x)Se(x) films, which exhibit n-type transport, large current densities (>10(5) A cm(-2)) and mobilities greater than 10 cm2 V(-1) s(-1)--an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

  19. Low bandgap semiconducting polymers for polymeric photovoltaics.

    Science.gov (United States)

    Liu, Chang; Wang, Kai; Gong, Xiong; Heeger, Alan J

    2016-08-22

    In order to develop high performance polymer solar cells (PSCs), full exploitation of the sun-irradiation from ultraviolet (UV) to near infrared (NIR) is one of the key factors to ensure high photocurrents and thus high efficiency. In this review, five of the effective design rules for approaching LBG semiconducting polymers with high molar absorptivity, suitable energy levels, high charge carrier mobility and high solubility in organic solvents are overviewed. These design stratagems include fused heterocycles for facilitating π-electron flowing along the polymer backbone, groups/atoms bridging adjacent rings for maintaining a high planarity, introduction of electron-withdrawing units for lowering the bandgap (Eg), donor-acceptor (D-A) copolymerization for narrowing Eg and 2-dimensional conjugation for broadened absorption and enhanced hole mobility. It has been demonstrated that LBG semiconducting polymers based on electron-donor units combined with strong electron-withdrawing units possess excellent electronic and optic properties, emerging as excellent candidates for efficient PSCs. While for ultrasensitive photodetectors (PDs), which have intensive applications in both scientific and industrial sectors, sensing from the UV to the NIR region is of critical importance. For polymer PDs, Eg as low as 0.8 eV has been obtained through a rational design stratagem, covering a broad wavelength range from the UV to the NIR region (1450 nm). However, the response time of the polymer PDs are severely limited by the hole mobility of LBG semiconducting polymers, which is significantly lower than those of the inorganic materials. Thus, further advancing the hole mobility of LBG semiconducting polymers is of equal importance as broadening the spectral response for approaching uncooled ultrasensitive broadband polymer PDs in the future study.

  20. 14th Conference on "Microscopy of Semiconducting Materials"

    CERN Document Server

    Hutchison, J

    2005-01-01

    This is a long-established international biennial conference series, organised in conjunction with the Royal Microscopical Society, Oxford, the Institute of Physics, London and the Materials Research Society, USA. The 14th conference in the series focused on the most recent advances in the study of the structural and electronic properties of semiconducting materials by the application of transmission and scanning electron microscopy. The latest developments in the use of other important microcharacterisation techniques were also covered and included the latest work using scanning probe microscopy and also X-ray topography and diffraction. Developments in materials science and technology covering the complete range of elemental and compound semiconductors are described in this volume.

  1. CNPC Appoints Chief Experts for Important Technological Projects

    Institute of Scientific and Technical Information of China (English)

    Zhao Jianzhong

    2006-01-01

    @@ On June 27th, China National Petroleum Corporation (CNPC) held a public recruitment to appoint chief experts in Beijing for its important technological projects, which is the first time for CNPC to appoint chief managers by the means of competitive recruitment. This recruitment covers four projects, such as drilling, logging, geophysical survey and ground engineering with 15 projects. Of those,there are 8 drilling projects, which make up 50 percent of all the important technological projects for public recruitment. CNPC expects to further boost the chief expert responsibility system and promote the research and development (R&D) of technological project on the basis of the public recruitment. The company completes the recruitment following the procedure of making announcement, conducting competitive recruitment and giving publicity. On July 25th, the appointment ceremony was held by CNPC and 15 experts were awarded the certificates. CNPC is entering a new stage for the implementation of the technology and talent strategy for the 11th Five-Year Plan. What's more, a new management mode is taking shape for the technological project and for the construction of technological personnel pool.

  2. Semiconducting III-V compounds

    CERN Document Server

    Hilsum, C; Henisch, Heinz R

    1961-01-01

    Semiconducting III-V Compounds deals with the properties of III-V compounds as a family of semiconducting crystals and relates these compounds to the monatomic semiconductors silicon and germanium. Emphasis is placed on physical processes that are peculiar to III-V compounds, particularly those that combine boron, aluminum, gallium, and indium with phosphorus, arsenic, and antimony (for example, indium antimonide, indium arsenide, gallium antimonide, and gallium arsenide).Comprised of eight chapters, this book begins with an assessment of the crystal structure and binding of III-V compounds, f

  3. Potential displacement of petroleum imports by solar energy technologies

    Energy Technology Data Exchange (ETDEWEB)

    DeLeon, P.; Jackson, B.L.; McNown, R.F.; Mahrenholz, G.J.

    1980-05-01

    The United States currently imports close to half of its petroleum requirements. This report delineates the economic, social, and political costs of such a foreign oil dependency. These costs are often intangible, but combined they clearly constitute a greater price for imported petroleum than the strictly economic cost. If we can assume that imported oil imposes significant socioeconomic costs upon the American economy and society, one way to reduce these costs is to develop alternative, domestic energy sources - such as solar energy technologies - which can displace foreign petroleum. The second half of this report estimates that by the year 2000, solar energy technologies can displace 3.6 quads of petroleum. This figure includes solar energy applications in utilities, industrial and agricultural process heat, and transportation. The estimate can be treated as a lower bound; if the United States were to achieve the proposed goal of 20 quads by 2000, the amount of displaced oil probably would be greater. Although all the displaced oil would not be imported, the reduction in imported petroleum would relieve many of the conditions that increase the present cost of foreign oil to the American consumer.

  4. Organic ferroelectric/semiconducting nanowire hybrid layer for memory storage

    Science.gov (United States)

    Cai, Ronggang; Kassa, Hailu G.; Haouari, Rachid; Marrani, Alessio; Geerts, Yves H.; Ruzié, Christian; van Breemen, Albert J. J. M.; Gelinck, Gerwin H.; Nysten, Bernard; Hu, Zhijun; Jonas, Alain M.

    2016-03-01

    Ferroelectric materials are important components of sensors, actuators and non-volatile memories. However, possible device configurations are limited due to the need to provide screening charges to ferroelectric interfaces to avoid depolarization. Here we show that, by alternating ferroelectric and semiconducting nanowires over an insulating substrate, the ferroelectric dipole moment can be stabilized by injected free charge carriers accumulating laterally in the neighboring semiconducting nanowires. This lateral electrostatic coupling between ferroelectric and semiconducting nanowires offers new opportunities to design new device architectures. As an example, we demonstrate the fabrication of an elementary non-volatile memory device in a transistor-like configuration, of which the source-drain current exhibits a typical hysteretic behavior with respect to the poling voltage. The potential for size reduction intrinsic to the nanostructured hybrid layer offers opportunities for the development of strongly miniaturized ferroelectric and piezoelectric devices.Ferroelectric materials are important components of sensors, actuators and non-volatile memories. However, possible device configurations are limited due to the need to provide screening charges to ferroelectric interfaces to avoid depolarization. Here we show that, by alternating ferroelectric and semiconducting nanowires over an insulating substrate, the ferroelectric dipole moment can be stabilized by injected free charge carriers accumulating laterally in the neighboring semiconducting nanowires. This lateral electrostatic coupling between ferroelectric and semiconducting nanowires offers new opportunities to design new device architectures. As an example, we demonstrate the fabrication of an elementary non-volatile memory device in a transistor-like configuration, of which the source-drain current exhibits a typical hysteretic behavior with respect to the poling voltage. The potential for size reduction

  5. DEVELOPMENT OF IMPORT-SUBSTITUTING TECHNOLOGIES FOR BUILDING MATERIAL PRODUCTION

    Directory of Open Access Journals (Sweden)

    N. I. Berezovsky

    2014-01-01

    Full Text Available The paper presents results of investigations on rational usage of mineral resources. In particular, it has shown the possibility to increase a period of raw material serviceability and its application for production of building products depending on chemical and mineralogical composition of the waste. Analysis of the executed investigations shows that import substitution of anthracite, lignite and black coal for local fuels (milled peat and its sub-standard product is possible in the production technology of porous building materials.A mathematical model for drying process has been developed in the paper. Technology for thermal performance of a sintering machine with calculation of its length at the given pallet speed has been proposed on the basis of the developed model. Once-through circulation of flue gases and heated materials is the main specific feature of belt sintering machines being used in production. In such a case the whole drying process can be divided into two periods: a period of constant drying rate and a period of falling drying rate. Calculations have shown that the drying rate depends on moisture content but it does not depend on heat exchange Bio-criteria, however, heating rate is a function of temperature and Biq. A mechanism of moisture transfer using various drying methods is the same as in an environment with constant temperature and so in an environment with variable temperature. Application of the mathematical model provides the possibility to save significantly power resources expended for drying process.The paper gives description of methodology for calculation of technologically important optimum parameters for sintering processes of agglomeration while using milled peat.

  6. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films

    KAUST Repository

    Sun, Ke

    2015-03-11

    Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiOx films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O2(g). © 2015, National Academy of Sciences. All rights reserved.

  7. Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films.

    Science.gov (United States)

    Sun, Ke; Saadi, Fadl H; Lichterman, Michael F; Hale, William G; Wang, Hsin-Ping; Zhou, Xinghao; Plymale, Noah T; Omelchenko, Stefan T; He, Jr-Hau; Papadantonakis, Kimberly M; Brunschwig, Bruce S; Lewis, Nathan S

    2015-03-24

    Reactively sputtered nickel oxide (NiOx) films provide transparent, antireflective, electrically conductive, chemically stable coatings that also are highly active electrocatalysts for the oxidation of water to O2(g). These NiOx coatings provide protective layers on a variety of technologically important semiconducting photoanodes, including textured crystalline Si passivated by amorphous silicon, crystalline n-type cadmium telluride, and hydrogenated amorphous silicon. Under anodic operation in 1.0 M aqueous potassium hydroxide (pH 14) in the presence of simulated sunlight, the NiOx films stabilized all of these self-passivating, high-efficiency semiconducting photoelectrodes for >100 h of sustained, quantitative solar-driven oxidation of water to O2(g).

  8. Semiconducting silicon nanowires for biomedical applications

    CERN Document Server

    Coffer, JL

    2014-01-01

    Biomedical applications have benefited greatly from the increasing interest and research into semiconducting silicon nanowires. Semiconducting Silicon Nanowires for Biomedical Applications reviews the fabrication, properties, and applications of this emerging material. The book begins by reviewing the basics, as well as the growth, characterization, biocompatibility, and surface modification, of semiconducting silicon nanowires. It goes on to focus on silicon nanowires for tissue engineering and delivery applications, including cellular binding and internalization, orthopedic tissue scaffol

  9. Ohmic contacts to semiconducting diamond

    Science.gov (United States)

    Zeidler, James R.; Taylor, M. J.; Zeisse, Carl R.; Hewett, C. A.; Delahoussaye, Paul R.

    1990-10-01

    Work was carried out to improve the electron beam evaporation system in order to achieve better deposited films. The basic system is an ion pumped vacuum chamber, with a three-hearth, single-gun e-beam evaporator. Four improvements were made to the system. The system was thoroughly cleaned and new ion pump elements, an e-gun beam adjust unit, and a more accurate crystal monitor were installed. The system now has a base pressure of 3 X 10(exp -9) Torr, and can easily deposit high-melting-temperature metals such as Ta with an accurately controlled thickness. Improved shadow masks were also fabricated for better alignment and control of corner contacts for electrical transport measurements. Appendices include: A Thermally Activated Solid State Reaction Process for Fabricating Ohmic Contacts to Semiconducting Diamond; Tantalum Ohmic Contacts to Diamond by a Solid State Reaction Process; Metallization of Semiconducting Diamond: Mo, Mo/Au, and Mo/Ni/Au; Specific Contact Resistance Measurements of Ohmic Contracts to Diamond; and Electrical Activation of Boron Implanted into Diamond.

  10. Rehabilitation Counselors' Perceptions of Importance and Competence of Assistive Technology

    Science.gov (United States)

    Kuo, Hung Jen

    2013-01-01

    Assistive technology (AT) has been identified as one of the most effective interventions for rehabilitation purposes of individuals with disabilities. Due to the positive potentials, assistive technology has attracted tremendous attention among the rehabilitation counselors during the past decades. As a result, numerous AT devices have been…

  11. Separated metallic and semiconducting single-walled carbon nanotubes: opportunities in transparent electrodes and beyond.

    Science.gov (United States)

    Lu, Fushen; Meziani, Mohammed J; Cao, Li; Sun, Ya-Ping

    2011-04-19

    Ever since the discovery of single-walled carbon nanotubes (SWNTs), there have been many reports and predictions on their superior properties for use in a wide variety of potential applications. However, an SWNT is either metallic or semiconducting; these properties are distinctively different in electrical conductivity and many other aspects. The available bulk-production methods generally yield mixtures of metallic and semiconducting SWNTs, despite continuing efforts in metallicity-selective nanotube growth. Presented here are significant advances and major achievements in the development of postproduction separation methods, which are now capable of harvesting separated metallic and semiconducting SWNTs from different production sources with sufficiently high enrichment and quantities for satisfying at least the needs in research and technological explorations. Opportunities and some available examples for the use of metallic SWNTs in transparent electrodes and semiconducting SWNTs in various device nanotechnologies are highlighted and discussed.

  12. Solidification and crystal growth of solid solution semiconducting alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lehoczky, S.L.; Szofran, F.R.

    1984-10-01

    Problems associated with the solidification and crytal growth of solid-solution semiconducting alloy crystals in a terrestrial environment are described. A detailed description is given of the results for the growth of mercury cadmium telluride (HgCdTe) alloy crystals by directional solidification, because of their considerable technological importance. A series of HgCdTe alloy crystals are grown from pseudobinary melts by a vertical Bridgman method using a wide range of growth rates and thermal conditions. Precision measurements are performed to establish compositional profiles for the crystals. The compositional variations are related to compositional variations in the melts that can result from two-dimensional diffusion or density gradient driven flow effects ahead of the growth interface. These effects are discussed in terms of the alloy phase equilibrium properties, the recent high temperature thermophysical data for the alloys and the highly unusual heat transfer characteristics of the alloy/ampule/furnace system that may readily lead to double diffusive convective flows in a gravitational environment.

  13. Meso-/Nanoporous Semiconducting Metal Oxides for Gas Sensor Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Duc Hoa

    2015-01-01

    Full Text Available Development and/or design of new materials and/or structures for effective gas sensor applications with fast response and high sensitivity, selectivity, and stability are very important issues in the gas sensor technology. This critical review introduces our recent progress in the development of meso-/nanoporous semiconducting metal oxides and their applications to gas sensors. First, the basic concepts of resistive gas sensors and the recent synthesis of meso-/nanoporous metal oxides for gas sensor applications are introduced. The advantages of meso-/nanoporous metal oxides are also presented, taking into account the crystallinity and ordered/disordered porous structures. Second, the synthesis methods of meso-/nanoporous metal oxides including the soft-template, hard-template, and temple-free methods are introduced, in which the advantages and disadvantages of each synthetic method are figured out. Third, the applications of meso-/nanoporous metal oxides as gas sensors are presented. The gas nanosensors are designed based on meso-/nanoporous metal oxides for effective detection of toxic gases. The sensitivity, selectivity, and stability of the meso-/nanoporous gas nanosensors are also discussed. Finally, some conclusions and an outlook are presented.

  14. Solidification and crystal growth of solid solution semiconducting alloys

    Science.gov (United States)

    Lehoczky, S. L.; Szofran, F. R.

    1984-01-01

    Problems associated with the solidification and crytal growth of solid-solution semiconducting alloy crystals in a terrestrial environment are described. A detailed description is given of the results for the growth of mercury cadmium telluride (HgCdTe) alloy crystals by directional solidification, because of their considerable technological importance. A series of HgCdTe alloy crystals are grown from pseudobinary melts by a vertical Bridgman method using a wide range of growth rates and thermal conditions. Precision measurements are performed to establish compositional profiles for the crystals. The compositional variations are related to compositional variations in the melts that can result from two-dimensional diffusion or density gradient driven flow effects ahead of the growth interface. These effects are discussed in terms of the alloy phase equilibrium properties, the recent high temperature thermophysical data for the alloys and the highly unusual heat transfer characteristics of the alloy/ampule/furnace system that may readily lead to double diffusive convective flows in a gravitational environment.

  15. VA INFORMATION TECHNOLOGY: Important Initiatives Begun, Yet Serious Vulnerabilities Persist

    Science.gov (United States)

    2007-11-02

    We appreciate the opportunity to join in today s hearing and share updated information on the Department of Veterans Affairs (VA) information ... technology (IT) program. As you know, IT is essential to VA s ability to effectively serve the veteran population and is the cornerstone of the department’s

  16. Assembly of ordered carbon shells on semiconducting nanomaterials

    Science.gov (United States)

    Sutter, Eli Anguelova; Sutter, Peter Werner

    2012-10-02

    In some embodiments of the invention, encapsulated semiconducting nanomaterials are described. In certain embodiments the nanostructures described are semiconducting nanomaterials encapsulated with ordered carbon shells. In some aspects a method for producing encapsulated semiconducting nanomaterials is disclosed. In some embodiments applications of encapsulated semiconducting nanomaterials are described.

  17. Assembly of ordered carbon shells on semiconducting nanomaterials

    Science.gov (United States)

    Sutter, Eli Anguelova; Sutter, Peter Werner

    2010-05-11

    In some embodiments of the invention, encapsulated semiconducting nanomaterials are described. In certain embodiments the nanostructures described are semiconducting nanomaterials encapsulated with ordered carbon shells. In some aspects a method for producing encapsulated semiconducting nanomaterials is disclosed. In some embodiments applications of encapsulated semiconducting nanomaterials are described.

  18. Importance of Computer Model Validation in Pyroprocessing Technology Development

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Y. E.; Li, Hui; Yim, M. S. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    In this research, we developed a plan for experimental validation of one of the computer models developed for ER process modeling, i. e., the ERAD code. Several candidate surrogate materials are selected for the experiment considering the chemical and physical properties. Molten salt-based pyroprocessing technology is being examined internationally as an alternative to treat spent nuclear fuel over aqueous technology. The central process in pyroprocessing is electrorefining(ER) which separates uranium from transuranic elements and fission products present in spent nuclear fuel. ER is a widely used process in the minerals industry to purify impure metals. Studies of ER by using actual spent nuclear fuel materials are problematic for both technical and political reasons. Therefore, the initial effort for ER process optimization is made by using computer models. A number of models have been developed for this purpose. But as validation of these models is incomplete and often times problematic, the simulation results from these models are inherently uncertain.

  19. An Assessment of the Importance of Technologies to Military Capabilities.

    Science.gov (United States)

    1980-10-01

    Utility Analysis ( MAUA ), is employed in studies requiring the quantification of complex alternatives that have values on a large number of alternatives...potential to enhance Soviet ICBM development programs pertaining to reentry vehicle heat shields and nose tips, and to bombs, bomblets, and rockets. MAUA ...the technology. A MAUA model is hierarchical in nature, starting with the specified top-level factor for which an overall score is desired. This

  20. The Importance of Localized Related Variety for International Diversification of Corporate Technology

    DEFF Research Database (Denmark)

    Dettmann, Eva; Lacasa, Iciar Dominguez; Günther, Jutta;

    2016-01-01

    The importance of localized related variety for international diversification of corporate technology, Regional Studies. Internationalization of research and development has increased substantially in recent years. This paper analyses the determinants of spatial distribution of foreign technologi......The importance of localized related variety for international diversification of corporate technology, Regional Studies. Internationalization of research and development has increased substantially in recent years. This paper analyses the determinants of spatial distribution of foreign...... technological activities. The estimations show that this is the case in regions characterized by a high overall technological strength. This suggests that related variety facilitates technological diversifications of foreign corporations in regions at the top of the geographic hierarchy...

  1. The Importance of Localized Related Variety for International Diversification of Corporate Technology

    DEFF Research Database (Denmark)

    Dettmann, Eva; Lacasa, Iciar Dominguez; Günther, Jutta

    2016-01-01

    The importance of localized related variety for international diversification of corporate technology, Regional Studies. Internationalization of research and development has increased substantially in recent years. This paper analyses the determinants of spatial distribution of foreign technologi......The importance of localized related variety for international diversification of corporate technology, Regional Studies. Internationalization of research and development has increased substantially in recent years. This paper analyses the determinants of spatial distribution of foreign...... technological activities across 96 regions in Germany. It identifies foreign technological activities by applying the cross-border ownership concept to patent applications. The main proposition is that regions with higher related variety of technological activities between sectors attract more foreign...... technological activities. The estimations show that this is the case in regions characterized by a high overall technological strength. This suggests that related variety facilitates technological diversifications of foreign corporations in regions at the top of the geographic hierarchy...

  2. Paul Tillich and Technology: His Importance for Robust Science, Technology, and Society (STS) Education.

    Science.gov (United States)

    Deitrich, Richard

    1990-01-01

    Discussed is the linkage between science, technology, and religious ideas. Tillich's continuum of existentialism, philosophy, and theology and his concepts of the multidimensional unity of life have been used to develop a technology and religion course. Included are the core ethic and basic tenets for STS education. (KR)

  3. The Importance of Introducing a Course on Information and Communication Technologies for Development into the Information Technology Curriculum

    Science.gov (United States)

    Al-Ahmad, Walid

    2010-01-01

    This paper studies the role and the importance of Information and Communication Technologies for Development (ICT4D) education in Information Technology (IT) programs. The research included the students who attended an ICT4D course at NYiT Amman Campus in the academic years of 2006 to 2009. Data were collected through two questionnaires developed…

  4. Semiconducting compounds and devices incorporating same

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J; Facchetti, Antonio; Boudreault, Pierre-Luc; Miyauchi, Hiroyuki

    2014-06-17

    Disclosed are molecular and polymeric compounds having desirable properties as semiconducting materials. Such compounds can exhibit desirable electronic properties and possess processing advantages including solution-processability and/or good stability. Organic transistor and photovoltaic devices incorporating the present compounds as the active layer exhibit good device performance.

  5. Semiconducting compounds and devices incorporating same

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Tobin J.; Facchetti, Antonio; Boudreault, Pierre-Luc; Miyauchi, Hiroyuki

    2016-01-19

    Disclosed are molecular and polymeric compounds having desirable properties as semiconducting materials. Such compounds can exhibit desirable electronic properties and possess processing advantages including solution-processability and/or good stability. Organic transistor and photovoltaic devices incorporating the present compounds as the active layer exhibit good device performance.

  6. Large-Area Semiconducting Graphene Nanomesh Tailored by Interferometric Lithography.

    Science.gov (United States)

    Kazemi, Alireza; He, Xiang; Alaie, Seyedhamidreza; Ghasemi, Javad; Dawson, Noel Mayur; Cavallo, Francesca; Habteyes, Terefe G; Brueck, Steven R J; Krishna, Sanjay

    2015-07-01

    Graphene nanostructures are attracting a great deal of interest because of newly emerging properties originating from quantum confinement effects. We report on using interferometric lithography to fabricate uniform, chip-scale, semiconducting graphene nanomesh (GNM) with sub-10 nm neck widths (smallest edge-to-edge distance between two nanoholes). This approach is based on fast, low-cost, and high-yield lithographic technologies and demonstrates the feasibility of cost-effective development of large-scale semiconducting graphene sheets and devices. The GNM is estimated to have a room temperature energy bandgap of ~30 meV. Raman studies showed that the G band of the GNM experiences a blue shift and broadening compared to pristine graphene, a change which was attributed to quantum confinement and localization effects. A single-layer GNM field effect transistor exhibited promising drive current of ~3.9 μA/μm and ON/OFF current ratios of ~35 at room temperature. The ON/OFF current ratio of the GNM-device displayed distinct temperature dependence with about 24-fold enhancement at 77 K.

  7. 31 CFR 545.205 - Prohibited importation of goods, software, technology, or services.

    Science.gov (United States)

    2010-07-01

    ..., software, technology, or services. 545.205 Section 545.205 Money and Finance: Treasury Regulations Relating..., software, technology, or services owned or controlled by the Taliban or persons whose property or interests... (AFGHANISTAN) SANCTIONS REGULATIONS Prohibitions § 545.205 Prohibited importation of goods, software...

  8. Formation of single-walled carbon nanotube thin films enriched with semiconducting nanotubes and their application in photoelectrochemical devices.

    Science.gov (United States)

    Wei, Li; Tezuka, Noriyasu; Umeyama, Tomokazu; Imahori, Hiroshi; Chen, Yuan

    2011-04-01

    Single-walled carbon nanotube (SWCNT) thin films, containing a high-density of semiconducting nanotubes, were obtained by a gel-centrifugation method. The agarose gel concentration and centrifugation force were optimized to achieve high semiconducting and metallic nanotube separation efficiency at 0.1 wt% agarose gel and 18,000g. The thickness of SWCNT films can be precisely controlled from 65 to 260 nm with adjustable transparency. These SWCNT films were applied in photoelectrochemical devices. Photocurrents generated by semiconducting SWCNT enriched films are 15-35% higher than those by unsorted SWCNT films. This is because of reducing exciton recombination channels as a result of the removal of metallic nanotubes. Thinner films generate higher photocurrents because charge carriers have less chances going in metallic nanotubes for recombination, before they can reach electrodes. Developing more scalable and selective methods for high purity semiconducting SWCNTs is important to further improve the photocurrent generation efficiency by using SWCNT-based photoelectrochemical devices.

  9. Electron transporting semiconducting polymers in organic electronics.

    Science.gov (United States)

    Zhao, Xingang; Zhan, Xiaowei

    2011-07-01

    Significant progress has been achieved in the preparation of semiconducting polymers over the past two decades, and successful commercial devices based on them are slowly beginning to enter the market. However, most of the conjugated polymers are hole transporting, or p-type, semiconductors that have seen a dramatic rise in performance over the last decade. Much less attention has been devoted to electron transporting, or n-type, materials that have lagged behind their p-type counterparts. Organic electron transporting materials are essential for the fabrication of organic p-n junctions, organic photovoltaic cells (OPVs), n-channel organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs) and complementary logic circuits. In this critical review we focus upon recent developments in several classes of electron transporting semiconducting polymers used in OLEDs, OFETs and OPVs, and survey and analyze what is currently known concerning electron transporting semiconductor architecture, electronic structure, and device performance relationships (87 references).

  10. Synthesis and Applications of Semiconducting Graphene

    Directory of Open Access Journals (Sweden)

    Shahrima Maharubin

    2016-01-01

    Full Text Available Semimetal-to-semiconductor transition in graphene can bestow graphene with numerous novel and enhanced structural, electrical, optical, and physicochemical characteristics. The scope of graphene and its prospective for an array of implications could be significantly outspread by this transition. In consideration of the recent advancements of semiconducting graphene, this article widely reviews the properties, production, and developing operations of this emergent material. The comparisons among the benefits and difficulties of current methods are made, intending to offer evidences to develop novel and scalable synthesis approaches. The emphasis is on the properties and applications resulting from various conversion methods (doping, controlled reduction, and functionalization, expecting to get improved knowledge on semiconducting graphene materials. Intending to motivate further efficient implications, the mechanisms leading to their beneficial usages for energy conversion and storage are also emphasized.

  11. Optical antenna effect in semiconducting nanowires.

    Science.gov (United States)

    Chen, G; Wu, Jian; Lu, Qiujie; Gutierrez, H R; Xiong, Qihua; Pellen, M E; Petko, J S; Werner, D H; Eklund, P C

    2008-05-01

    We report on investigations of the interaction of light with nanoscale antennae made from crystalline GaP nanowires (NWs). Using Raman scattering, we have observed strong optical antenna effects which we identify with internal standing wave photon modes of the wire. The antenna effects were probed in individual NWs whose diameters are in the range 40 optical antenna effect" in semiconducting NWs is essential to the analysis of all electro-optic effects in small diameter filaments.

  12. Efficient technologies or user behaviour, which is the more important when reducing households' energy consumption?

    DEFF Research Database (Denmark)

    Gram-Hanssen, Kirsten

    2013-01-01

    Much policy effort focuses on energy efficiency of technology, though not only efficiency but also user behaviour is an important factor influencing the amount of consumed energy. This paper explores to what extent energy efficiency of appliances and houses or user behaviour is the more important...... and Danish national statistics. These Danish data are discussed together with international studies. Through the presentation of these different projects and examples, it is shown how user behaviour is at least as important as the efficiency of technology when explaining households' energy consumption...... in Denmark. In the conclusion, these results are discussed in a broader international perspective and it is concluded that more research in this field is necessary. In relation to energy policy, it is argued that it is not a question of technology efficiency or behaviour, as both have to be included...

  13. Degadation of semiconducting polymers by concentrated sunlight

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Manceau, Matthieu; Petersen, Martin Helgesen

    2011-01-01

    A lens based sunlight concentration setup was used to accelerate the degradation of semiconducting polymers. Sunlight was collected outdoor and focused into an optical fiber bundle allowing for indoor experimental work. Photo-degradation of several polymers was studied by UV–vis absorbance...... spectroscopy and infra-red spectroscopy. This showed that the degradation rate is significantly increased by increasing illumination intensity. Acceleration factors exceeding 100 compared to standard 1 sun illumination were observed for solar concentration of 200 suns in the case of P3HT. A comparison between...

  14. Recent advances in visible-light-responsive photocatalysts for hydrogen production and solar energy conversion--from semiconducting TiO2 to MOF/PCP photocatalysts.

    Science.gov (United States)

    Horiuchi, Yu; Toyao, Takashi; Takeuchi, Masato; Matsuoka, Masaya; Anpo, Masakazu

    2013-08-28

    The present perspective describes recent advances in visible-light-responsive photocatalysts intended to develop novel and efficient solar energy conversion technologies, including water splitting and photofuel cells. Water splitting is recognized as one of the most promising techniques to convert solar energy as a clean and abundant energy resource into chemical energy in the form of hydrogen. In recent years, increasing concern is directed to not only the development of new photocatalytic materials but also the importance of technologies to produce hydrogen and oxygen separately. Photofuel cells can convert solar energy into electrical energy by decomposing bio-related compounds and livestock waste as fuels. The advances of photocatalysts enabling these solar energy conversion technologies have been going on since the discovery of semiconducting titanium dioxide materials and have extended to organic-inorganic hybrid materials, such as metal-organic frameworks and porous coordination polymers (MOF/PCP).

  15. The importance of the technologically able social innovators and entrepreneurs: A US National Laboratory Perspective

    NARCIS (Netherlands)

    Chavez, Victor; Stinnett, Regan; Tierney, Robert; Tierney, Robert; Walsh, Steven Thomas

    2017-01-01

    A country's National Innovation Policies (NIP) often center on military, energy or other national security missions. Yet many countries' NIPs have resulted in tremendous societal benefit through both planned and unplanned action not associated with these goals. Socially important technology product

  16. Biologically templated assembly of hybrid semiconducting nanomesh for high performance field effect transistors and sensors

    Science.gov (United States)

    Byeon, Hye-Hyeon; Lee, Seung-Woo; Lee, Eun-Hee; Kim, Woong; Yi, Hyunjung

    2016-10-01

    Delicately assembled composites of semiconducting nanomaterials and biological materials provide an attractive interface for emerging applications, such as chemical/biological sensors, wearable health monitoring devices, and therapeutic agent releasing devices. The nanostructure of composites as a channel and a sensing material plays a critical role in the performance of field effect transistors (FETs). Therefore, it is highly desirable to prepare elaborate composite that can allow the fabrication of high performance FETs and also provide high sensitivity and selectivity in detecting specific chemical/biological targets. In this work, we demonstrate that high performance FETs can be fabricated with a hydrodynamically assembled composite, a semiconducting nanomesh, of semiconducting single-walled carbon nanotubes (S-SWNTs) and a genetically engineered M13 phage to show strong binding affinity toward SWNTs. The semiconducting nanomesh enables a high on/off ratio (~104) of FETs. We also show that the threshold voltage and the channel current of the nanomesh FETs are sensitive to the change of the M13 phage surface charge. This biological gate effect of the phage enables the detection of biologically important molecules such as dopamine and bisphenol A using nanomesh-based FETs. Our results provide a new insight for the preparation of composite material platform for highly controllable bio/electronics interfaces.

  17. Biologically templated assembly of hybrid semiconducting nanomesh for high performance field effect transistors and sensors

    Science.gov (United States)

    Byeon, Hye-Hyeon; Lee, Seung-Woo; Lee, Eun-Hee; Kim, Woong; Yi, Hyunjung

    2016-01-01

    Delicately assembled composites of semiconducting nanomaterials and biological materials provide an attractive interface for emerging applications, such as chemical/biological sensors, wearable health monitoring devices, and therapeutic agent releasing devices. The nanostructure of composites as a channel and a sensing material plays a critical role in the performance of field effect transistors (FETs). Therefore, it is highly desirable to prepare elaborate composite that can allow the fabrication of high performance FETs and also provide high sensitivity and selectivity in detecting specific chemical/biological targets. In this work, we demonstrate that high performance FETs can be fabricated with a hydrodynamically assembled composite, a semiconducting nanomesh, of semiconducting single-walled carbon nanotubes (S-SWNTs) and a genetically engineered M13 phage to show strong binding affinity toward SWNTs. The semiconducting nanomesh enables a high on/off ratio (~104) of FETs. We also show that the threshold voltage and the channel current of the nanomesh FETs are sensitive to the change of the M13 phage surface charge. This biological gate effect of the phage enables the detection of biologically important molecules such as dopamine and bisphenol A using nanomesh-based FETs. Our results provide a new insight for the preparation of composite material platform for highly controllable bio/electronics interfaces. PMID:27762315

  18. Abnormal hopping conduction in semiconducting polycrystalline graphene

    Science.gov (United States)

    Park, Jeongho; Mitchel, William C.; Elhamri, Said; Grazulis, Larry; Altfeder, Igor

    2013-07-01

    We report the observation of an abnormal carrier transport phenomenon in polycrystalline semiconducting graphene grown by solid carbon source molecular beam epitaxy. At the lowest temperatures in samples with small grain size, the conduction does not obey the two-dimensional Mott-type variable-range hopping (VRH) conduction often reported in semiconducting graphene. The hopping exponent p is found to deviate from the 1/3 value expected for Mott VRH with several samples exhibiting a p=2/5 dependence. We also show that the maximum energy difference between hopping sites is larger than the activation energy for nearest-neighbor hopping, violating the assumptions of the Mott model. The 2/5 dependence more closely agrees with the quasi-one-dimensional VRH model proposed by Fogler, Teber, and Shklovskii (FTS). In the FTS model, conduction occurs by tunneling between neighboring metallic wires. We suggest that metallic edge states and conductive grain boundaries play the role of the metallic wires in the FTS model.

  19. Technology Transfer in the EU: Exporting Strategically Important ICT Solutions to Other EU Member States

    Directory of Open Access Journals (Sweden)

    Säär Anni

    2015-10-01

    Full Text Available The fast development of ICTs pose new challenges to the European Union and its Member States. Every EU country has its own policies regarding technology transfer, ownership of state e-services, and the possibilities how the state-owned or licensed e-service could be exported. Taking into account the free movement of goods, the EU has created a platform to cooperate and export IT solutions. However, the lack of preparedness of infrastructures, legislation and stakeholders for cross-border exchanges poses a threat to IT transfer and should be taken into consideration in the EU as well. In the coming decades the number of outsourced ICT solutions, strategically important ICT solutions, public services and critically important information exchange platforms developed on behalf of the states, will grow exponentially. Still, digital development is uneven across the EU, they grow at different speeds and the performance is quite splintered. There are legal provisions which are outdated and therefore impede technological cooperation and export of IT solutions. A Member State may restrict the ICT licensing based on national security and policy reasons and the ownership of intellectual property might pose a threat to technology transfer or further development of the IT solution. There are examples of strategically important export of ICT solutions, the experience at which can be expanded to cover other EU Member States. Strong collaboration would enable mutual learning from past experiences along with the opportunities for better use of technology. Parallels can be drawn with military technology transfers, as the policies and legal framework was first developed and mostly used with them.

  20. Are Lipases Still Important Biocatalysts? A Study of Scientific Publications and Patents for Technological Forecasting.

    Science.gov (United States)

    Daiha, Karina de Godoy; Angeli, Renata; de Oliveira, Sabrina Dias; Almeida, Rodrigo Volcan

    2015-01-01

    The great potential of lipases is known since 1930 when the work of J. B. S. Haldane was published. After eighty-five years of studies and developments, are lipases still important biocatalysts? For answering this question the present work investigated the technological development of four important industrial sectors where lipases are applied: production of detergent formulations; organic synthesis, focusing on kinetic resolution, production of biodiesel, and production of food and feed products. The analysis was made based on research publications and patent applications, working as scientific and technological indicators, respectively. Their evolution, interaction, the major players of each sector and the main subject matters disclosed in patent documents were discussed. Applying the concept of technology life cycle, S-curves were built by plotting cumulative patent data over time to monitor the attractiveness of each technology for investment. The results lead to a conclusion that the use of lipases as biocatalysts is still a relevant topic for the industrial sector, but developments are still needed for lipase biocatalysis to reach its full potential, which are expected to be achieved within the third, and present, wave of biocatalysis.

  1. Are Lipases Still Important Biocatalysts? A Study of Scientific Publications and Patents for Technological Forecasting.

    Directory of Open Access Journals (Sweden)

    Karina de Godoy Daiha

    Full Text Available The great potential of lipases is known since 1930 when the work of J. B. S. Haldane was published. After eighty-five years of studies and developments, are lipases still important biocatalysts? For answering this question the present work investigated the technological development of four important industrial sectors where lipases are applied: production of detergent formulations; organic synthesis, focusing on kinetic resolution, production of biodiesel, and production of food and feed products. The analysis was made based on research publications and patent applications, working as scientific and technological indicators, respectively. Their evolution, interaction, the major players of each sector and the main subject matters disclosed in patent documents were discussed. Applying the concept of technology life cycle, S-curves were built by plotting cumulative patent data over time to monitor the attractiveness of each technology for investment. The results lead to a conclusion that the use of lipases as biocatalysts is still a relevant topic for the industrial sector, but developments are still needed for lipase biocatalysis to reach its full potential, which are expected to be achieved within the third, and present, wave of biocatalysis.

  2. Efficient technologies or user behaviour, which is the more important when reducing households' energy consumption?

    Energy Technology Data Exchange (ETDEWEB)

    Gram-Hanssen, K. [Danish Building Research Institute, Aalborg University, A.C. Meyers Vaenge 15, 2450 Copenhagen (Denmark)

    2013-08-15

    Much policy effort focuses on energy efficiency of technology, though not only efficiency but also user behaviour is an important factor influencing the amount of consumed energy. This paper explores to what extent energy efficiency of appliances and houses or user behaviour is the more important, both for understanding why some households consume much more energy than others, and when looking for relevant approaches to a future low-carbon society. The paper uses several sources to explore this question, most of them from a Danish context, including results from the researcher's own projects and Danish national statistics. These Danish data are discussed together with international studies. Through the presentation of these different projects and examples, it is shown how user behaviour is at least as important as the efficiency of technology when explaining households' energy consumption in Denmark. In the conclusion, these results are discussed in a broader international perspective and it is concluded that more research in this field is necessary. In relation to energy policy, it is argued that it is not a question of technology efficiency or behaviour, as both have to be included in future policy if energy demand is actually to be reduced. Furthermore, it is also argued that not only individual behaviour is relevant, but also a broader perspective on collectively shared low-carbon practices has to be promoted.

  3. Ordered Semiconducting Nitrogen-Graphene Alloys

    Directory of Open Access Journals (Sweden)

    H. J. Xiang

    2012-01-01

    Full Text Available The interaction between substitutional nitrogen atoms in graphene is studied by performing first-principles calculations. The effective nearest-neighbor interaction between nitrogen dopants is found to be highly repulsive because of the strong electrostatic repulsion between nitrogen atoms. This interaction prevents the full nitrogen-carbon phase separation in nitrogen-doped graphene. Interestingly, there are two relatively stable nitrogen-nitrogen pair configurations, whose stability can be attributed to the anisotropy in the charge redistribution induced by nitrogen doping. We reveal two stable, ordered, semiconducting N-doped graphene structures, C_{3}N and C_{12}N, through the cluster-expansion technique and particle-swarm optimization method. In particular, we show that C_{12}N has a direct band gap of 0.98 eV. The heterojunctions between C_{12}N and graphene nanoribbons might be a promising basis for organic solar cells.

  4. Bulk semiconducting scintillator device for radiation detection

    Energy Technology Data Exchange (ETDEWEB)

    Stowe, Ashley C.; Burger, Arnold; Groza, Michael

    2016-08-30

    A bulk semiconducting scintillator device, including: a Li-containing semiconductor compound of general composition Li-III-VI.sub.2, wherein III is a Group III element and VI is a Group VI element; wherein the Li-containing semiconductor compound is used in one or more of a first mode and a second mode, wherein: in the first mode, the Li-containing semiconductor compound is coupled to an electrical circuit under bias operable for measuring electron-hole pairs in the Li-containing semiconductor compound in the presence of neutrons and the Li-containing semiconductor compound is also coupled to current detection electronics operable for detecting a corresponding current in the Li-containing semiconductor compound; and, in the second mode, the Li-containing semiconductor compound is coupled to a photodetector operable for detecting photons generated in the Li-containing semiconductor compound in the presence of the neutrons.

  5. Doping Scheme of Semiconducting Atomic Chains

    Science.gov (United States)

    Toshishige, Yamada; Saini, Subhash (Technical Monitor)

    1998-01-01

    Atomic chains, precise structures of atomic scale created on an atomically regulated substrate surface, are candidates for future electronics. A doping scheme for intrinsic semiconducting Mg chains is considered. In order to suppress the unwanted Anderson localization and minimize the deformation of the original band shape, atomic modulation doping is considered, which is to place dopant atoms beside the chain periodically. Group I atoms are donors, and group VI or VII atoms are acceptors. As long as the lattice constant is long so that the s-p band crossing has not occurred, whether dopant atoms behave as donors or acceptors is closely related to the energy level alignment of isolated atomic levels. Band structures are calculated for Br-doped (p-type) and Cs-doped (n-type) Mg chains using the tight-binding theory with universal parameters, and it is shown that the band deformation is minimized and only the Fermi energy position is modified.

  6. The Importance of Knowledge Management in Terms of Increasing Social Capital in Selected Slovene Technology Parks

    Directory of Open Access Journals (Sweden)

    Riko Novak

    2013-12-01

    Full Text Available This article investigates the importance of knowledge management (KM and how it is influencing social capital (SC in selected organisations that are members of Slovene technology parks. The purpose of this article is to point out statistical important characteristics between the dependant variable and several independent variables on the basis of preliminary studied empirical data based on a population of 667 organisations chosen from the subjects of the innovative environment database maintained by the Public Agency of the Republic of Slovenia for Entrepreneurship and Foreign Investments (JAPTI. On the basis of a multivariate regression analysis we wanted to present empirical findings, namely, whether communication technologies and the capability (ability of the employed to access information sources influences KM. With this article we want to present the final findings which define the development of a conceptual framework for understanding the influence of KM in small and medium sized companies on the development of social capital. We came to the conclusion that in an organisation the importance of intellectual and social capital, intangible capital assets and their continuous measurement has to be emphasised in order to increase the importance (awareness of KM.

  7. IMPORTANCE OF COMPUTER TECHNOLOGY IN REALIZATION OF CULTURAL AND EDUCATIONAL TASKS OF PRESCHOOL INSTITUTIONS

    Directory of Open Access Journals (Sweden)

    Zvezdan Arsić

    2016-06-01

    Full Text Available The rapid scientific and technological development imposes numerous changes in all spheres of life and work. In such circumstances, a computer has become a part of all aspects of life: economy, education, free time, family. Since children in contemporary society increasingly acquire knowledge before the school age, the question is how to prepare them for the world in which we live, bearing in mind how significantly different it is from the world in which the previous generations grew up. The research was aimed at examining the attitudes of preschool teachers about the importance of computers in the realization of educational activities in preschool institutions. The study included 54 teachers from Kosovo and Metohija: Kosovska Mitrovica, Donja Gušterica and Ropotovo. The research results indicate that digital technology is a very important and a useful didactic tool in the realization of educational activities in preschool institutions and that preschool teachers have the required competence to implement the technology. However, they are not satisfied with the quality of their ICT education and training during their studies; they also feel that their institutions do not provide adequate working conditions for the use of computers in the realization of educational tasks.

  8. Importance of Program Development Competencies for Agricultural Extension Agents' Performance in Process of Technology Transfer

    Directory of Open Access Journals (Sweden)

    Neda Tiraieyari

    2010-01-01

    Full Text Available Problem statement: The movement of technology from lab to the field has been a challenge for agricultural extension agents. In this study researchers focused on program development competencies for agricultural extension agents in process of technology transfer and discuss the importance of these competencies by determining the relationship between these competencies and performance of extension agents. Approach: The study employed stratified random sampling technique. The sample consisted of 210 extension agents in four states of Malaysia. The data were analyzed using descriptive statistics, Pearson correlation and multiple regression analysis. Results: Extension agents perceived themselves competent in developing program planning, program implementation and program evaluation. The findings supported the positive relationship between competencies and extension agents’ performance. Therefore hypothesis of the study was supported. The results of multiple regressions showed program development competencies explained 0.448 of variance of extension agents’ performance. Conclusion/Recommendations: It can be concluded that performance of extension agents is expected to increase if they have program development competencies. Results supported the importance of these competencies for performance of extension agents in process of technology transfer. Hence to keep extension agents competent and to further improve their performance, these competencies must be considered and upgraded. Continuous assessment of extension agents’ competencies and performance is recommended.

  9. Nanogenerator comprising piezoelectric semiconducting nanostructures and Schottky conductive contacts

    Science.gov (United States)

    Wang, Zhong L. (Inventor); Wang, Xudong (Inventor); Song, Jinhui (Inventor); Zhou, Jun (Inventor); He, Jr-Hau (Inventor)

    2011-01-01

    A semiconducting device includes a substrate, a piezoelectric wire, a structure, a first electrode and a second electrode. The piezoelectric wire has a first end and an opposite second end and is disposed on the substrate. The structure causes the piezoelectric wire to bend in a predetermined manner between the first end and the second end so that the piezoelectric wire enters a first semiconducting state. The first electrode is coupled to the first end and the second electrode is coupled to the second end so that when the piezoelectric wire is in the first semiconducting state, an electrical characteristic will be exhibited between the first electrode and the second electrode.

  10. High-Purity Semiconducting Single-Walled Carbon Nanotubes: A Key Enabling Material in Emerging Electronics.

    Science.gov (United States)

    Lefebvre, Jacques; Ding, Jianfu; Li, Zhao; Finnie, Paul; Lopinski, Gregory; Malenfant, Patrick R L

    2017-09-13

    Semiconducting single-walled carbon nanotubes (sc-SWCNTs) are emerging as a promising material for high-performance, high-density devices as well as low-cost, large-area macroelectronics produced via additive manufacturing methods such as roll-to-roll printing. Proof-of-concept demonstrations have indicated the potential of sc-SWCNTs for digital electronics, radiofrequency circuits, radiation hard memory, improved sensors, and flexible, stretchable, conformable electronics. Advances toward commercial applications bring numerous opportunities in SWCNT materials development and characterization as well as fabrication processes and printing technologies. Commercialization in electronics will require large quantities of sc-SWCNTs, and the challenge for materials science is the development of scalable synthesis, purification, and enrichment methods. While a few synthesis routes have shown promising results in making near-monochiral SWCNTs, gram quantities are available only for small-diameter sc-SWCNTs, which underperform in transistors. Most synthesis routes yield mixtures of SWCNTs, typically 30% metallic and 70% semiconducting, necessitating the extraction of sc-SWCNTs from their metallic counterparts in high purity using scalable postsynthetic methods. Numerous routes to obtain high-purity sc-SWCNTs from raw soot have been developed, including density-gradient ultracentrifugation, chromatography, aqueous two-phase extraction, and selective DNA or polymer wrapping. By these methods (termed sorting or enrichment), >99% sc-SWCNT content can be achieved. Currently, all of these approaches have drawbacks and limitations with respect to electronics applications, such as excessive dilution, expensive consumables, and high ionic impurity content. Excess amount of dispersant is a common challenge that hinders direct inclusion of sc-SWCNTs into electronic devices. At present, conjugated polymer extraction may represent the most practical route to sc-SWCNTs. By the use of

  11. Semiconducting Metal Oxide Based Sensors for Selective Gas Pollutant Detection

    Directory of Open Access Journals (Sweden)

    Marsha C. Kanan

    2009-10-01

    Full Text Available A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO based sensors for the selective and sensitive detection of various environmental pollutants is presented.

  12. Aviation Technology Life Cycle Management: Importance for Aviation Companies, Aerospace Industry Organizations and Relevant Stakeholders

    Directory of Open Access Journals (Sweden)

    Stanislav Szabo

    2017-04-01

    Full Text Available The paper in the introductory part underlines some aspects concerning the importance of Aviation Technology Life Cycle Management and informs on basic international standards for the processes and stages of life cycle. The second part is focused on definition and main objectives of system life cycle management. The authors subsequently inform on system life cycle stages (in general and system life cycle processes according to ISO/IEC/IEEE 15288:2015 standard. Following the fact, that life cycle cost (LCC is inseparable part and has direct connection to the life cycle management, the paper contains brief information regarding to LCC (cost categories, cost breakdown structure, cost estimation a.o.. Recently was issued the first part of Aviation Technology Life Cycle Management monograph (in Slovak: ”Manažment životného cyklu leteckej techniky I”, written by I.Koblen and S.Szabo. Following this fact and direct relation to the topic of article it is a part of article briefly introduced the content of two parts of this monograph (the 2nd part of monograph it has been prepared for the print. The last part of article is focused on issue concerning main assumptions and conditions for successful application of aviation technology life cycle management in aviation companies, aerospace industry organizations as well as from the relevant stakeholders side.

  13. Scientific and Technological Innovation Is an Important Approach to Ensuring China's Oil Security

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    With the rapid and continual growth of national economy, the gap between oil demand and supply keeps widening in China, therefore China will increasingly depend on imported oil. However, the world's oil and gas resources are unevenly distributed; global world's oil prices remain high; and over 70 percent of China's imported oil has to be shipped through the Malacca Strait. There are various ways to ensure China's oil security today, and the practical and feasible strategic option is to increase the discovery and production of domestic oil, raise energy efficiency and develop petroleum substitutes. Scientific and technological innovation is crucial both in new oil reserves discovery and production,energy conservation, and in the development of petroleum substitutes, establishment of a strategic oil reserve system and for environment protection. This indicates that China should take effective measures in investment strategy, fiscal policies, financing instruments, intellectual property protection, fostering talents and professionals, so as to establish its own scientific and technological innovation system in the petroleum industry and be better able to ensure oil security.

  14. Emissivity and electrooptical properties of semiconducting quantum dots/rods and liquid crystal composites: a review

    Science.gov (United States)

    Singh, Gautam; Fisch, Michael; Kumar, Satyendra

    2016-05-01

    Investigations of the mixtures of semiconducting quantum scale particles in anisotropic liquid crystal (LC) medium have become a vibrant area of research primarily due to their very interesting phenomenology. The results of these investigations fall into four groups: (i) Photoluminescent emissive properties of the quantum particles ordinarily depend on the size, shape, and chemical nature of the particles. These undergo important changes in their spectrum, polarization, and isotropy of emission when dissolved in an anisotropic LC phase. Moreover, their response to external stimuli such as mechanical, optical, or electric fields is altered in important ways; (ii) physical properties of LCs such as viscosity, dielectric relaxation, etc are modified by the addition of quantum particles. Their presence in ferroelectric smectic LC is known to give rise to an antiferro- to ferri-electric phase transition and suppresses the paraelectric phase; (iii) switching characteristics of LC devices are altered in important ways by the addition of quantum particles. Their threshold voltage is usually lowered, contrast ratio, and switching speed of nematic, ferroelectric, and cholesteric devices may increase or decrease depending on the concentration, applied field, and particle anisotropy; and (iv) controlled aggregation of quantum particles at the interface between isotropic and LC domains, near added polystyrene beads, and in the vicinity of point defects gives rise to interesting photonic structures, enables studies of photon antibunching and single photon sources. Clearly, there is a need to understand the basic and applied aspects of these systems and find routes to their technological applications including sensors, electrooptical devices, and solar energy harvesting. This review provides an overview of recent work involving liquid crystals and a variety of quantum particles.

  15. Emissivity and electrooptical properties of semiconducting quantum dots/rods and liquid crystal composites: a review.

    Science.gov (United States)

    Singh, Gautam; Fisch, Michael; Kumar, Satyendra

    2016-05-01

    Investigations of the mixtures of semiconducting quantum scale particles in anisotropic liquid crystal (LC) medium have become a vibrant area of research primarily due to their very interesting phenomenology. The results of these investigations fall into four groups: (i) Photoluminescent emissive properties of the quantum particles ordinarily depend on the size, shape, and chemical nature of the particles. These undergo important changes in their spectrum, polarization, and isotropy of emission when dissolved in an anisotropic LC phase. Moreover, their response to external stimuli such as mechanical, optical, or electric fields is altered in important ways; (ii) physical properties of LCs such as viscosity, dielectric relaxation, etc are modified by the addition of quantum particles. Their presence in ferroelectric smectic LC is known to give rise to an antiferro- to ferri-electric phase transition and suppresses the paraelectric phase; (iii) switching characteristics of LC devices are altered in important ways by the addition of quantum particles. Their threshold voltage is usually lowered, contrast ratio, and switching speed of nematic, ferroelectric, and cholesteric devices may increase or decrease depending on the concentration, applied field, and particle anisotropy; and (iv) controlled aggregation of quantum particles at the interface between isotropic and LC domains, near added polystyrene beads, and in the vicinity of point defects gives rise to interesting photonic structures, enables studies of photon antibunching and single photon sources. Clearly, there is a need to understand the basic and applied aspects of these systems and find routes to their technological applications including sensors, electrooptical devices, and solar energy harvesting. This review provides an overview of recent work involving liquid crystals and a variety of quantum particles.

  16. Spray printing of organic semiconducting single crystals.

    Science.gov (United States)

    Rigas, Grigorios-Panagiotis; Payne, Marcia M; Anthony, John E; Horton, Peter N; Castro, Fernando A; Shkunov, Maxim

    2016-11-22

    Single-crystal semiconductors have been at the forefront of scientific interest for more than 70 years, serving as the backbone of electronic devices. Inorganic single crystals are typically grown from a melt using time-consuming and energy-intensive processes. Organic semiconductor single crystals, however, can be grown using solution-based methods at room temperature in air, opening up the possibility of large-scale production of inexpensive electronics targeting applications ranging from field-effect transistors and light-emitting diodes to medical X-ray detectors. Here we demonstrate a low-cost, scalable spray-printing process to fabricate high-quality organic single crystals, based on various semiconducting small molecules on virtually any substrate by combining the advantages of antisolvent crystallization and solution shearing. The crystals' size, shape and orientation are controlled by the sheer force generated by the spray droplets' impact onto the antisolvent's surface. This method demonstrates the feasibility of a spray-on single-crystal organic electronics.

  17. Spray printing of organic semiconducting single crystals

    Science.gov (United States)

    Rigas, Grigorios-Panagiotis; Payne, Marcia M.; Anthony, John E.; Horton, Peter N.; Castro, Fernando A.; Shkunov, Maxim

    2016-11-01

    Single-crystal semiconductors have been at the forefront of scientific interest for more than 70 years, serving as the backbone of electronic devices. Inorganic single crystals are typically grown from a melt using time-consuming and energy-intensive processes. Organic semiconductor single crystals, however, can be grown using solution-based methods at room temperature in air, opening up the possibility of large-scale production of inexpensive electronics targeting applications ranging from field-effect transistors and light-emitting diodes to medical X-ray detectors. Here we demonstrate a low-cost, scalable spray-printing process to fabricate high-quality organic single crystals, based on various semiconducting small molecules on virtually any substrate by combining the advantages of antisolvent crystallization and solution shearing. The crystals' size, shape and orientation are controlled by the sheer force generated by the spray droplets' impact onto the antisolvent's surface. This method demonstrates the feasibility of a spray-on single-crystal organic electronics.

  18. Response functions of semiconducting lithium indium diselenide

    Energy Technology Data Exchange (ETDEWEB)

    Lukosi, Eric; Chvala, Ondrej [University of Tennessee, Knoxville, TN (United States); Stowe, Ashley [University of Tennessee, Knoxville, TN (United States); Y-12 National Security Complex, Oak Ridge, TN (United States)

    2016-06-21

    This paper presents the results of a computational investigation that determined the gamma-ray and neutron response functions of a new semiconducting material, {sup 6}LiInSe{sub 2}, which is very sensitive to thermal neutrons. Both MCNP6 simulations and custom post-processing/simulation techniques were used to determine various detection properties of LISe. The computational study included consideration of energetic electron escape, the contribution from the activation of {sup 115}In and subsequent decay of {sup 116}In, triton and alpha particle escape from the {sup 6}Li reaction pathway, and the effect of incomplete charge collection when detecting neutrons via the {sup 6}Li reaction pathway. The result of neutron detection with incomplete charge collection was compared to experimental results and showed general agreement, where holes exhibit a lower mobility-lifetime product than electrons, as expected for compound semiconductors. - Highlights: • Charged particle escape does not significantly affect measured neutron spectra. • Energetic electron escape affects gamma-induced spectra. • LISe has a small photoelectric cross section for high energy gamma-rays. • Excellent gamma/neutron discrimination capability. • Activated {sup 116}In does not readily interfere with {sup 6}Li-based neutron signal.

  19. Fabrication of bright and small size semiconducting polymer nanoparticles for cellular labelling and single particle tracking

    Science.gov (United States)

    Wei, Lin; Zhou, Peng; Yang, Qingxiu; Yang, Qiaoyu; Ma, Ming; Chen, Bo; Xiao, Lehui

    2014-09-01

    In this work, we demonstrate a convenient and robust strategy for efficient fabrication of high fluorescence quantum yield (QY, 49.8 +/- 3%) semiconducting polymer nanoparticles (SPNs), with size comparable with semiconductor quantum dots (Qdots). The SPNs were synthesized by co-precipitation of hydrophobic semiconducting polymer together with amphiphilic multidentate polymer. Comprehensive spectroscopic and microscopic characterizations showed that the SPNs possess superior photophysical performance, with excellent fluorescence brightness and reduced photoblinking in contrast with Qdots, as well as good photostability compared to a fluorescent protein of a similar size, phycoerythrin. More importantly, by conjugating membrane biomarkers onto the surface of SPNs, it was found that they were not only suitable for specific cellular labelling but also for single particle tracking because of the improved optical performance.In this work, we demonstrate a convenient and robust strategy for efficient fabrication of high fluorescence quantum yield (QY, 49.8 +/- 3%) semiconducting polymer nanoparticles (SPNs), with size comparable with semiconductor quantum dots (Qdots). The SPNs were synthesized by co-precipitation of hydrophobic semiconducting polymer together with amphiphilic multidentate polymer. Comprehensive spectroscopic and microscopic characterizations showed that the SPNs possess superior photophysical performance, with excellent fluorescence brightness and reduced photoblinking in contrast with Qdots, as well as good photostability compared to a fluorescent protein of a similar size, phycoerythrin. More importantly, by conjugating membrane biomarkers onto the surface of SPNs, it was found that they were not only suitable for specific cellular labelling but also for single particle tracking because of the improved optical performance. Electronic supplementary information (ESI) available: Experimental section and additional supporting results as noted in the text

  20. Why Are Omics Technologies Important to Understanding the Role of Nutrition in Inflammatory Bowel Diseases?

    Directory of Open Access Journals (Sweden)

    Lynnette R. Ferguson

    2016-10-01

    Full Text Available For many years, there has been confusion about the role that nutrition plays in inflammatory bowel diseases (IBD. It is apparent that good dietary advice for one individual may prove inappropriate for another. As with many diseases, genome-wide association studies across large collaborative groups have been important in revealing the role of genetics in IBD, with more than 200 genes associated with susceptibility to the disease. These associations provide clues to explain the differences in nutrient requirements among individuals. In addition to genes directly involved in the control of inflammation, a number of the associated genes play roles in modulating the gut microbiota. Cell line models enable the generation of hypotheses as to how various bioactive dietary components might be especially beneficial for certain genetic groups. Animal models are necessary to mimic aspects of the complex aetiology of IBD, and provide an important link between tissue culture studies and human trials. Once we are sufficiently confident of our hypotheses, we can then take modified diets to an IBD population that is stratified according to genotype. Studies in IBD patients fed a Mediterranean-style diet have been important in validating our hypotheses and as a proof-of-principle for the application of these sensitive omics technologies to aiding in the control of IBD symptoms.

  1. Why Are Omics Technologies Important to Understanding the Role of Nutrition in Inflammatory Bowel Diseases?

    Science.gov (United States)

    Ferguson, Lynnette R.; Barnett, Matthew P. G.

    2016-01-01

    For many years, there has been confusion about the role that nutrition plays in inflammatory bowel diseases (IBD). It is apparent that good dietary advice for one individual may prove inappropriate for another. As with many diseases, genome-wide association studies across large collaborative groups have been important in revealing the role of genetics in IBD, with more than 200 genes associated with susceptibility to the disease. These associations provide clues to explain the differences in nutrient requirements among individuals. In addition to genes directly involved in the control of inflammation, a number of the associated genes play roles in modulating the gut microbiota. Cell line models enable the generation of hypotheses as to how various bioactive dietary components might be especially beneficial for certain genetic groups. Animal models are necessary to mimic aspects of the complex aetiology of IBD, and provide an important link between tissue culture studies and human trials. Once we are sufficiently confident of our hypotheses, we can then take modified diets to an IBD population that is stratified according to genotype. Studies in IBD patients fed a Mediterranean-style diet have been important in validating our hypotheses and as a proof-of-principle for the application of these sensitive omics technologies to aiding in the control of IBD symptoms. PMID:27775675

  2. Thin-film transistors with a channel composed of semiconducting metal oxide nanoparticles deposited from the gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Busch, C., E-mail: Claudia.Busch@uni-due.de; Schierning, G.; Theissmann, R.; Nedic, A.; Kruis, F. E.; Schmechel, R. [University of Duisburg-Essen, Faculty of Engineering and Center for NanoIntegration Duisburg-Essen (CeNIDE) (Germany)

    2012-06-15

    The fabrication of semiconducting functional layers using low-temperature processes is of high interest for flexible printable electronics applications. Here, the one-step deposition of semiconducting nanoparticles from the gas phase for an active layer within a thin-film transistor is described. Layers of semiconducting nanoparticles with a particle size between 10 and 25 nm were prepared by the use of a simple aerosol deposition system, excluding potentially unwanted technological procedures like substrate heating or the use of solvents. The nanoparticles were deposited directly onto standard thin-film transistor test devices, using thermally grown silicon oxide as gate dielectric. Proof-of-principle experiments were done deploying two different wide-band gap semiconducting oxides, tin oxide, SnO{sub x}, and indium oxide, In{sub 2}O{sub 3}. The tin oxide spots prepared from the gas phase were too conducting to be used as channel material in thin-film transistors, most probably due to a high concentration of oxygen defects. Using indium oxide nanoparticles, thin-film transistor devices with significant field effect were obtained. Even though the electron mobility of the investigated devices was only in the range of 10{sup -6} cm{sup 2V-1s-1}, the operability of this method for the fabrication of transistors was demonstrated. With respect to the possibilities to control the particle size and layer morphology in situ during deposition, improvements are expected.

  3. THE IMPORTANCE AND THE ROLES OF INFORMATION TECHNOLOGIES IN PRESCHOOL EDUCATION

    Directory of Open Access Journals (Sweden)

    Nazım BURGUL

    2008-06-01

    Full Text Available The aim of this research is to determine the importance and the roles of the existing informationtechnologies in preschool education and to do a content analysis.The research is done by using the descriptive study method which is one of the general scanning models. Having examinedthe results of the previous researches, the theoretical framework that would light the way for the research was prepared. Theavailable information about the subject was scanned from resources such as documents, other written sources and also theinternet, and expert’s opinions were asked for. The content analysis of the collected information was done.The preschool period is a process to which all education scientists attach great importance. However, in order to realize theaim of this process, well planned education programmes are needed. The preschool education period provides crèche,nursery and reception education activities. Because of the annual changes of education technologies, positive differences areseen for the teaching activities in this area. On the other hand, there are some requirements to do to speed up the educationand to increase the productivity of education in our present day information society.The preschool education programmes are “the Crèche Programme (0-36 months”, “The Nursery Programme (37-60months and “The Reception Programme (61-72 months”. Optimum educational programs must be prepared for activitiesthat will take place on a daily basis according to specific aims and attitudes to determine the educational status of theseactivities. After having examined the technology-based education model, it is observed by the evaluation and assessmentdiscipline that using equipment such as tv, radio, computer, video, projection, overhead projector and slide apparatus makesthe learning process more effective and productive.As a result, information has become the most expensive product today. The roles of computer-aided education and the

  4. An Investigation of the Attitudes of the National Teams’ Coaches Towards the Role and Importance of Information Technology in Sport

    Directory of Open Access Journals (Sweden)

    Nasim Salehi

    2011-01-01

    Full Text Available In order to investigate the attitude of elite coaches of the team and individual sports towards the role and importance of information technology in sport, 132 coaches were chosen as a sample and answered to the questionnaire of the role of information technology in sport organised by Liebermann and Katz that consisted of 3 different sections: A General attitude of the coaches towards computer and technology; B The importance of science and technology in achieving coaching experience; C Understanding science and technology in sport. Descriptive and inferential statistics (CFA and independent t - test were used in order to analyse the data. The findings demonstrated that elite coaches selected two aims as their chief ones: 1 - Winning medals in competitions; 2- Having a good relationship with the athletes. There was not any significant relationship between the attitudes of the men and women and the coaches of the individual and team sports on science and technology. It seems that elite coaches are aware on the general importance of sport sciences and have a positive attitude towards the use of sport technologies. But they do not practically transfer this positive attitude to competitive sport environments even when they use information technology for other purposes. Eventually it can be stated that the attitude of the coaches towards technology is very positive and consequently it is a must to find strategies in order to encourage them to use current technology and science practically.

  5. Semiconducting polyacetylene materials for energy-conversion applications

    Science.gov (United States)

    Kiss, Z.; Weinberger, B.

    1982-03-01

    Well controlled growth of semiconducting polyacetylene films by the Ziegler catalyst method was achieved. Thermal isomerization to the trans-(CH)/sub x/stage has yielded (CH)/sub x/films of p-type doping with an acceptor concentration of 10 to the sixteenth to 10 to the 17th power cu cm. Initial proof of concept experiments were also performed to grow polyacetylene by a plasma assisted process. The band edge of (CH)/sub x/ was measured. The technique consisted of measuring the photoresponse of a reverse biased (CH)/sub x/ solar cell, and studying the cut off in the response. The (CH)/sub x/ films had a band gap in the range of 1.4 to 1.5 eV, in good agreement with the measurement of absorption. A very important result of the successful demonstration of this technique is that very low absorption coefficients can be measured quite easily, yielding invaluable data on band tails in (CH)/sub x/.

  6. Polarons in semiconducting polymers: Study within an extended Holstein model

    Science.gov (United States)

    Meisel, K. D.; Vocks, H.; Bobbert, P. A.

    2005-05-01

    We present a study of electron- (hole-) phonon interaction and polaron formation in semiconducting polymers within an extended Holstein model. A minimization of the lowest electronic state of this Hamiltonian with respect to lattice degrees of freedom yields the polaronic ground state. Input parameters of this Hamiltonian are obtained from ab initio calculations based on the density-functional theory. We calculate optical phonon modes and the coupling constants of these modes to the highest occupied and lowest unoccupied molecular orbital bands, respectively. For the studied polymers [polythiophene, poly(phenylenevinylene), poly(para-phenylene)] the polaron binding energy, its size, and the lattice deformation as a function of conjugation length have been determined. Self-trapped polarons are found for long conjugation lengths. Energies of prominent PPV modes involved in polaron formation agree with infrared spectra. The polaron binding energies we find are much smaller than the width of the energy disorder in polymeric systems of practical importance, thus self-trapping effects can be ignored in practice.

  7. Rapid and real-time detection technologies for emerging viruses of biomedical importance

    Indian Academy of Sciences (India)

    M M Parida

    2008-11-01

    The development of technologies with rapid and sensitive detection capabilities and increased throughput have become crucial for responding to greater number threats posed by emerging and re-emerging viruses in the recent past. The conventional identification methods require time-consuming culturing, and/ or detection of antibodies, which are not very sensitive and specific. The recent advances in molecular biology techniques in the field of genomics and proteomics greatly facilitate the rapid identification with more accuracy. We have developed two real-time assays i.e., SYBR green I based real time reverse transcription polymerase chain reaction (RT-PCR) and RT-loop-mediated isothermal amplification (LAMP) assay for rapid detection as well as typing of some of the emerging viruses of biomedical importance viz. dengue, Japanese encephalitis, chikungunya, west Nile, severe acute respiratory syndrome virus (SARS) etc. Both these techniques are capable of detection and differentiation as well as quantifying viral load with higher sensitivity, rapidity, specificity. One of the most important advantages of LAMP is its field applicability, without requirement of any sophisticated equipments. Both these assays have been extensively evaluated and validated with clinical samples of recent epidemics from different parts of India. The establishment of these real time molecular assays will certainly facilitate the rapid detection of viruses with high degree of precision and accuracy in future.

  8. Semiconducting polymer single crystals and devices (Conference Presentation)

    Science.gov (United States)

    Dong, Huanli

    2016-11-01

    Highly ordered organic semiconductors in solid state with optimal molecular packing are critical to their electrical performance. Single crystals with long-range molecular orders and nearly perfect molecular packing are the best candidates, which already have been verified to exhibit the highest performance whether based on inorganic or small organic materials. However, in comparison, preparing high quality polymer crystals remains a big challenge in polymer science because of the easy entanglements of the long and flexible polymer chains during self-assembly process, which also significantly limits the development of their crystalline polymeric electronic devices. Here we have carried out systematical investigations to prepare high quality semiconducting polymers and high performance semiconducting polymer crystal optoelectronic devices have been successfully fabricated. The semiconducting polymeric devices demonstrate significantly enhanced charge carreir transport compared to their thin films, and the highest carreir mobiltiy could be approcahing 30 cm2 V-1s-1, one of the highest mobiltiy values for polymer semiconductors.

  9. Dielectrophoretic assembly of semiconducting single-walled carbon nanotube transistor

    Institute of Scientific and Technical Information of China (English)

    Se-Hun KWON; Young-Keun JEONG; Soongeun KWON; Myung-Chang KANG; Hyung-Woo LEE

    2011-01-01

    A novel burning technique for making a semiconducting single-walled carbon nanotubes (SWNTs) transistor assembled by the dielectrophoretic force was suggested. The fabrication process consisted of two steps. First, to align and attach a bundle of SWNTs between the source and drain, the alternating (AC) voltage was applied to the electrodes. When a bundle of SWNTs was connected between two electrodes, some of metallic nanotubes and semi-conducing nanotubes existed together. The second step is to burn the metallic SWNTS by applying the voltage between two electrodes. With increasing the voltage, more current flowed through the metallic SWNTs, thus, the metallic SWNTs burnt earlier than the semiconducting one. This technique enables to obtain only semi-conducting SWNTs connection in the transistor. Through the I-Vcharacteristic graph, the moment of metallic SWNTs burning and the characteristic of semi-conducing nanotubes were verified.

  10. Superconductivity in an Inhomogeneous Bundle of Metallic and Semiconducting Nanotubes

    Directory of Open Access Journals (Sweden)

    Ilya Grigorenko

    2013-01-01

    Full Text Available Using Bogoliubov-de Gennes formalism for inhomogeneous systems, we have studied superconducting properties of a bundle of packed carbon nanotubes, making a triangular lattice in the bundle's transverse cross-section. The bundle consists of a mixture of metallic and doped semiconducting nanotubes, which have different critical transition temperatures. We investigate how a spatially averaged superconducting order parameter and the critical transition temperature depend on the fraction of the doped semiconducting carbon nanotubes in the bundle. Our simulations suggest that the superconductivity in the bundle will be suppressed when the fraction of the doped semiconducting carbon nanotubes will be less than 0.5, which is the percolation threshold for a two-dimensional triangular lattice.

  11. Semiconducting glasses: A new class of thermoelectric materials?

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, A.P., E-mail: apg@itn.pt [Instituto Tecnologico e Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa/CFMC-UL, P-2686-953 Sacavem (Portugal); Lopes, E.B. [Instituto Tecnologico e Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa/CFMC-UL, P-2686-953 Sacavem (Portugal); Delaizir, G. [SPCTS, UMR CNRS 7315, Centre Europeen de la Ceramique, 12 rue Atlantis, 87068 Limoges (France); Vaney, J.B.; Lenoir, B. [Institut Jean Lamour, UMR 7198 CNRS-Nancy Universite-UPVM, Ecole Nationale Superieure des Mines de Nancy, Parc de Saurupt, F-54042 Nancy (France); Piarristeguy, A.; Pradel, A. [Institut Charles Gerhardt (ICG), UMR 5253 CNRS, Universite de Montpellier 2, 34095 Montpellier (France); Monnier, J.; Ochin, P.; Godart, C. [CNRS, ICMPE, CMTR, 2/8 rue Henri Dunant, 94320 Thiais (France)

    2012-09-15

    The deeper understanding of the factors that affect the dimensionless figure of merit, ZT, and the use of new synthetic methods has recently led to the development of novel systems with improved thermoelectric performances. Albeit up to now with ZT values lower than the conventional bulk materials, semiconducting glasses have also emerged as a new family of potential thermoelectric materials. This paper reviews the latest advances on semiconducting glasses for thermoelectric applications. Key examples of tellurium-based glasses, with high Seebeck coefficients, very low thermal conductivities and tunable electrical conductivities, are presented. ZT values as high as 0.2 were obtained at room temperature for several tellurium-based glasses with high copper concentrations, confirming chalcogenide semiconducting glasses as good candidates for high-performance thermoelectric materials. However, the temperature stability and electrical conductivity of the reported glasses are still not good enough for practical applications and further studies are still needed to enhance them. - Graphical abstract: Power factor as a function of the temperature for the Cu{sub 27.5}Ge{sub 2.5}Te{sub 70} and Cu{sub 30}As{sub 15}Te{sub 55} seniconducting glasses. Highlights: Black-Right-Pointing-Pointer A review of semiconducting glasses for thermoelectrics applications is presented. Black-Right-Pointing-Pointer The studied semiconducting glasses present very low thermal conductivities. Black-Right-Pointing-Pointer Composition can tune electrical conductivity and Seebeck coefficient. Black-Right-Pointing-Pointer ZT=0.2 is obtained at 300 K for different semiconducting glasses.

  12. Selective synthesis and device applications of semiconducting single-walled carbon nanotubes using isopropyl alcohol as feedstock.

    Science.gov (United States)

    Che, Yuchi; Wang, Chuan; Liu, Jia; Liu, Bilu; Lin, Xue; Parker, Jason; Beasley, Cara; Wong, H-S Philip; Zhou, Chongwu

    2012-08-28

    The development of guided chemical vapor deposition (CVD) growth of single-walled carbon nanotubes provides a great platform for wafer-scale integration of aligned nanotubes into circuits and functional electronic systems. However, the coexistence of metallic and semiconducting nanotubes is still a major obstacle for the development of carbon-nanotube-based nanoelectronics. To address this problem, we have developed a method to obtain predominantly semiconducting nanotubes from direct CVD growth. By using isopropyl alcohol (IPA) as the carbon feedstock, a semiconducting nanotube purity of above 90% is achieved, which is unambiguously confirmed by both electrical and micro-Raman measurements. Mass spectrometric study was performed to elucidate the underlying chemical mechanism. Furthermore, high performance thin-film transistors with an on/off ratio above 10(4) and mobility up to 116 cm(2)/(V·s) have been achieved using the IPA-synthesized nanotube networks grown on silicon substrate. The method reported in this contribution is easy to operate and the results are highly reproducible. Therefore, such semiconducting predominated single-walled carbon nanotubes could serve as an important building block for future practical and scalable carbon nanotube electronics.

  13. Direct effect of ownership and technology import: Firm level evidence from large and medium-enterprises in Shanghai

    Institute of Scientific and Technical Information of China (English)

    ZHU Pingfang; LI Lei

    2007-01-01

    This paper explores the direct effect of ownership and technology imports under the fiamework of neoclassical economic theory.The econometric analysis is based on panel data from a random sample of large and mediumenterprises in Shanghai,during the period of 1998 to 2003.The results show that Sino-foreign joint ventures,Sino-foralgn cooperative enterprises and foreignfunded enterprises (SANZI) enjoy higher labor productivity and total factor productlvity (TFP) than domestic enterprises.Intra-firm diffusion of non-codified technology,proxied by ovwnership,is the main source of their better performance,whereas internally transferred codified technology makes little contribution to TFP.For state-owned enterprises,codified technology imports have significantly raised both labor productivity and TFP,but such positive effect is significantly dependent on the S&T human resource.In contrast,no evidence supports that introduction of foreign technology has enhanced the productivity in domestic nonstate-owned enterprises.The empirical results indicate that SANZI do not have a distinct advantage in their codified technology.In addition,inadequate investment in assimilation process and research and development together with inefficient management of science and technology activities,may impede the use of imported technology.

  14. Orienting semi-conducting π-conjugated polymers.

    Science.gov (United States)

    Brinkmann, Martin; Hartmann, Lucia; Biniek, Laure; Tremel, Kim; Kayunkid, Navaphun

    2014-01-01

    The present review focuses on the recent progress made in thin film orientation of semi-conducting polymers with particular emphasis on methods using epitaxy and shear forces. The main results reported in this review deal with regioregular poly(3-alkylthiophene)s and poly(dialkylfluorenes). Correlations existing between processing conditions, macromolecular parameters and the resulting structures formed in thin films are underlined. It is shown that epitaxial orientation of semi-conducting polymers can generate a large palette of semi-crystalline and nanostructured morphologies by a subtle choice of the orienting substrates and growth conditions.

  15. A Detailed Analysis over Some Important Issues towards Using Computer Technology into the EFL Classrooms

    Science.gov (United States)

    Gilakjani, Abbas Pourhosein

    2014-01-01

    Computer technology has changed the ways we work, learn, interact and spend our leisure time. Computer technology has changed every aspect of our daily life--how and where we get our news, how we order goods and services, and how we communicate. This study investigates some of the significant issues concerning the use of computer technology…

  16. ICT security- aspects important for nuclear facilities; Information and Communication Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Thunem, Atoosa P-J.

    2005-09-15

    Rapid application growth of complex Information and Communication Technologies (ICT) in every society and state infrastructure as well as industry has revealed vulnerabilities that eventually have given rise to serious security breaches. These vulnerabilities together with the course of the breaches from cause to consequence are gradually about to convince the field experts that ensuring the security of ICT-driven systems is no longer possible by only relying on the fundaments of computer science, IT, or telecommunications. Appropriating knowledge from other disciplines is not only beneficial, but indeed very necessary. At the same time, it is a common observation today that ICT-driven systems are used everywhere, from the nuclear, aviation, commerce and healthcare domains to camera-equipped web-enabled cellular phones. The increasing interdisciplinary and inter-sectoral aspects of ICT security worldwide have been providing updated and useful information to the nuclear domain, as one of the emerging users of ICT-driven systems. Nevertheless, such aspects have also contributed to new and complicated challenges, as ICT security for the nuclear domain is in a much more delicate manner than for any other domains related to the concept of safety, at least from the public standpoint. This report addresses some important aspects of ICT security that need to be considered at nuclear facilities. It deals with ICT security and the relationship between security and safety from a rather different perspective than usually observed and applied. The report especially highlights the influence on the security of ICT-driven systems by all other dependability factors, and on that basis suggests a framework for ICT security profiling, where several security profiles are assumed to be valid and used in parallel for each ICT-driven system, sub-system or unit at nuclear facilities. The report also covers a related research topic of the Halden Project with focus on cyber threats and

  17. Tough, semiconducting polyethylene-poly(3-hexylthiophene) diblock copolymers

    DEFF Research Database (Denmark)

    Müller, C.; Goffri, S.; Breiby, Dag Werner

    2007-01-01

    Semiconducting diblock copolymers of polyethylene (PE) and regioregular poly(3-hexylthiophene) (P3HT) are demonstrated to exhibit a rich phase behaviour, judicious use of which permitted us to fabricate field-effect transistors that show saturated charge carrier mobilities, mu(FET), as high as 2 ...

  18. Ultrafast spectroscopy of semiconducting and multiferroic materials

    Science.gov (United States)

    Lou, Shitao

    In this thesis, we have used ultrafast spectroscopy to study the optical properties of two semiconductors, GaAs and Ge, and one hexagonal multiferroic material, LuMnO3. Both semiconductor and multiferroic materials are of great importance technologically and economically. By using ultrafast spectroscopy, we obtained time resolved electron and phonon dynamics directly, which is unavailable by conventional optical methods. Electron-hole pairs, coherent phonon oscillations and an optical coherence response are excited when femtosecond laser pulses interact with either GaAs or Ge crystals. The coherent phonon mode excited in GaAs/Ge is of T 2/T2g symmetry as determined by probe beam polarization analysis. The pump polarization dependence of the phonon oscillation is consistent with the transient stimulated Raman scattering (TSRS) mechanism. From the pump polarization dependence of the phonon oscillation, we have identified two excitation mechanisms contributing to the coherent phonon in GaAs, one is consistent with TSRS, and the other is consistent with screening effect of photoexcited electrons. The femtosecond laser pulse, with 800 nm center wavelength and polarized perpendicular to the c axis of LuMnO3, excites a narrow intra-atomic dxy, x2--y2 to d3z2--r2 transition in Mn. This excitation results in a transient reflectivity change for light of the same wavelength and polarization, by partial saturation of the transition. The relaxation time of this electronic excitation is about 1 ps. Furthermore, the electronic excitation resonantly excites a coherent optical phonon with A1 symmetry (TO: 118 cm--1 and LO: 120 cm --1), involving Lu ions motion along the c-axis, which is identified to be the soft mode driving the ferroelectric transition. A remarkable reversal of the sign of the oscillation amplitude (pi phase shift) of the reflectivity curve was observed upon comparing longitudinal optical (LO) with transverse optical (TO) mode geometries. The phase reversal is

  19. Pi-Stack Engineering of Semiconducting Perylene Tetracarboxylic Derivatives

    Science.gov (United States)

    Xue, Chenming

    D crystalline intra-layer order. Chapter 4, PDI pi-stacking order has been engineered in the crystalline phase. By introducing two structuring factors, a series of crystalline PDIs with finely tunable PDI pi-stacking order was obtained. The crystalline PDIs with exceptionally red-shifted lambda max were obtained. Several PDIs possess lambdamax values greater than any literature-reported ones. These materials can be excellent candidates in solar cell devices. In Chapter 5, new chiral main-chain PDI containing polymers were synthesized. These polymers can form intramolecular helical pi-stacks in diluted solutions. In Chapter 6, a novel synthetic route leading to unsymmetrical perylene tetracarboxylic derivatives has been developed. Based on this synthetic method, more perylene tetracarboxylic derivatives can be generated. In my research in this thesis, not only synthesis is an important part because it provides novel materials, but the characterization is critical as well. Infrared spectroscopy, Ultra-violet, fluorescence, differential scanning calorimetry, circular dichroism, polarized light microscopy, gel permeation chromatography, X-ray diffraction including both small angle and wide angle have been used. Additionally, molecular simulation is also very useful in design and obtaining details in molecular packing. Overall, the achievements in this research contribute a considerable advance in the field of generating semiconducting perylene tetracarboxylic derivatives which have versatile potential applications such as in solar cell devices, organic field effect transistors and light emitting diodes.

  20. The Effect of the Semiconductive Screen on Space Charge Suppression in Cross-Linked Polyethylene

    Science.gov (United States)

    Li, Lin; Han, Bai; Song, Wei; Wang, Xuan; Lei, Qing-Quan

    2014-10-01

    The space charge distributions of cross-linked polyethylene (XLPE) with Borouge's Borlink™ semiconductive screen type LE0550 and LE0595 from a pulsed electro-acoustic method are obtained. The contact interface morphology at the semiconductive screen and the structure of XLPE near the interface are characterized. The dielectric spectrum and the conductivity current of XLPE with the different semiconductive electrodes are compared. The semiconductive screen changes the structure and the dielectric characteristic of XLPE near the contact interface, which may be the main reason for space charge suppression in XLPE with Borouge's type LE0550 semiconductive screen.

  1. Minimum Viable Product and the Importance of Experimentation in Technology Startups

    Directory of Open Access Journals (Sweden)

    Dobrila Rancic Moogk

    2012-03-01

    Full Text Available Entrepreneurs are often faced with limited resources in their quest to commercialize new technology. This article presents the model of a lean startup, which can be applied to an organization regardless of its size or environment. It also emphasizes the conditions of extreme uncertainty under which the commercialization of new technology is carried out. The lean startup philosophy advocates efficient use of resources by introducing a minimum viable product to the market as soon as possible in order to test its value and the entrepreneur’s growth projections. This testing is done by running experiments that examine the metrics relevant to three distinct types of the growth. These experiments bring about accelerated learning to help reduce the uncertainty that accompanies commercialization projects, thereby bringing the resulting new technology to market faster.

  2. Human Resources or Information Technology: What is More Important for Companies in the Digital Era?

    National Research Council Canada - National Science Library

    Lejla Turulja; Nijaz Bajgorić

    2016-01-01

    .... On the other side, there is an increasing importance of human resource management (HRM) practices related to IT utilization, which are important for the business performance of a company in the rapidly changing knowledge-based economy...

  3. The Importance of Still Teaching the iGeneration: New Technologies and the Centrality of Pedagogy

    Science.gov (United States)

    Philip, Thomas M.; Garcia, Antero D.

    2013-01-01

    In this essay, Philip and Garcia argue that visions of mobile devices in the classroom often draw on assumptions about the inherent interests youth have in these devices, the capability of these interests to transfer from out-of-school contexts to the classroom, and the capacity for these new technologies to equalize the educational playing field.…

  4. The importance of technological innovation in the logistics of ethanol exports

    Directory of Open Access Journals (Sweden)

    José Petraglia

    2011-07-01

    Full Text Available This paper analyzes the technological status of the bulk liquids logistical process at the port of Santos. The main objective is to identify problems encountered in port logistics for the export of ethanol and evaluate their respective technological innovation perspectives. Ethanol exports have increased given international environmental appeals. Within the complex and uncertain environments that contemporary corporations are experiencing, environmental issues have captured global attention. There is an awareness as to the relevance of reducing pollutant emissions to the atmosphere and one of the manners of so doing is by utilising ethanol as a source of propulsion energy fuelling automobile engines. Brazil is one of largest, high quality, ethanol producers in the world and a strong competitor to serve the global market given that the quality of the port logistic infrastructure poses significant impact on exports. Thus, this article proposes to further deepen the theory fundamentals alongside research conducted at companies of South-central Brazil´s sugar alcohol supply chain sector. The study´s analytical model is based on bibliographical research, monitoring and descriptive field surveys at companies within the segment. The article demonstrates that although the logistical process is evolving technologically, further investments in logistic infrastructure is required so as to obtain a sustainable competitive advantage and ensure the feasibility of exports of the Brazilian product.Key words: logistic process, technological innovation and ethanol.

  5. Markets for Technology and the Importance of Firm-Specific Search for Innovation Performance

    DEFF Research Database (Denmark)

    Sofka, Wolfgang; Grimpe, Christoph

    , the costs of firm-specific search are only justified in underdeveloped markets. Otherwise, market transactions provide higher efficiency and flexibility. This negative cross-level interaction effect is stronger the more knowledge in an industry is covered by markets for technology. We test and support...

  6. Markets for Technology and the Importance of Firm-specific Search for Innovation Performance

    DEFF Research Database (Denmark)

    Grimpe, Christoph; Sofka, Wolfgang

    , the costs of firm-specific search are only justified in underdeveloped markets. Otherwise, market transactions provide higher efficiency and flexibility. This negative cross-level interaction effect is stronger the more knowledge in an industry is covered by markets for technology. We test and support...

  7. The Importance of Design Thinking for Technological Literacy: A Phenomenological Perspective

    Science.gov (United States)

    Wells, Alastair

    2013-01-01

    "We know that progress depends on discovery, inventions, creativity and design, but we have simply supposed that it happens anyway," de Bono (1999 p. 43). Technology education is ostensibly a foundation for future designers and creative thinking. However evidence of good design or creative thinking in outcomes displayed in school…

  8. Strategic Management of Educational Technology--The Importance of Leadership and Management

    Science.gov (United States)

    Moser, Franziska Zellweger

    2007-01-01

    Through case study research critical leadership and management tasks are identified regarding the integration of educational technology in teaching at research universities. The institutions studied, regardless their different characteristics and approaches, face common difficulties in engaging "second-wave" faculty. Furthermore, the coordination…

  9. The Importance of Design Thinking for Technological Literacy: A Phenomenological Perspective

    Science.gov (United States)

    Wells, Alastair

    2013-01-01

    "We know that progress depends on discovery, inventions, creativity and design, but we have simply supposed that it happens anyway," de Bono (1999 p. 43). Technology education is ostensibly a foundation for future designers and creative thinking. However evidence of good design or creative thinking in outcomes displayed in school…

  10. Paying for Joint or Single Audits? The Importance of Auditor Pairings and Differences in Technology Efficiency

    DEFF Research Database (Denmark)

    Holm, Claus; Thinggaard, Frank

    2016-01-01

    In the first theoretical paper on joint audits, Deng et al. predict that the audit fees for joint audits will be lower than those from single audits. However, the prediction depends on the combination of audit firms involved in the joint audit and on their technology efficiency as well...... as on the liability involved. This paper is the first to empirically test the predictions. Our findings from Denmark do not indicate any general difference in audit fees when two audit firms – regardless of combination and technology efficiency – conduct the statutory audit compared to a single Big audit firm....... The results indicate the existence of fixed coordination costs in joint audits. We do, however, find higher audit fees in Big-Small joint audits when the Small audit firm has a share of less than 25 per cent. This may reflect free-riding concerns....

  11. International careers and career success of Indian women in science & technology : The importance of career capital and organizational capital

    NARCIS (Netherlands)

    Valk, R.; van der Velde, E.G.; van Engen, Marloes

    2014-01-01

    This article presents a study on international careers and career success of Indian women in Science & Technology (S&T). We conducted interviews with 30 (upper) middle class Indian women in New Delhi and Bangalore (India) who pursued careers abroad as self-initiated expatriates (SIEs). Important

  12. International careers and career success of Indian women in science & technology : The importance of career capital and organizational capital

    NARCIS (Netherlands)

    Valk, R.; van der Velde, E.G.; van Engen, Marloes

    2014-01-01

    This article presents a study on international careers and career success of Indian women in Science & Technology (S&T). We conducted interviews with 30 (upper) middle class Indian women in New Delhi and Bangalore (India) who pursued careers abroad as self-initiated expatriates (SIEs). Important ele

  13. Optically transparent semiconducting polymer nanonetwork for flexible and transparent electronics

    Science.gov (United States)

    Yu, Kilho; Park, Byoungwook; Kim, Geunjin; Kim, Chang-Hyun; Park, Sungjun; Kim, Jehan; Jung, Suhyun; Jeong, Soyeong; Kwon, Sooncheol; Kang, Hongkyu; Kim, Junghwan; Yoon, Myung-Han; Lee, Kwanghee

    2016-12-01

    Simultaneously achieving high optical transparency and excellent charge mobility in semiconducting polymers has presented a challenge for the application of these materials in future “flexible” and “transparent” electronics (FTEs). Here, by blending only a small amount (˜15 wt %) of a diketopyrrolopyrrole-based semiconducting polymer (DPP2T) into an inert polystyrene (PS) matrix, we introduce a polymer blend system that demonstrates both high field-effect transistor (FET) mobility and excellent optical transparency that approaches 100%. We discover that in a PS matrix, DPP2T forms a web-like, continuously connected nanonetwork that spreads throughout the thin film and provides highly efficient 2D charge pathways through extended intrachain conjugation. The remarkable physical properties achieved using our approach enable us to develop prototype high-performance FTE devices, including colorless all-polymer FET arrays and fully transparent FET-integrated polymer light-emitting diodes.

  14. Unexpected semiconducting properties in few-layer arsenene

    CERN Document Server

    Zhang, Z Y; Xue, D S; Si, M S; Zhang, G P

    2014-01-01

    We demonstrate few-layer arsenene similar to phosphorene, which are derived from the or- thorhombic bulk arsenic but are thermally stable, semiconducting and of high carrier mobility. Although its monolayer is an indirect bandgap semiconductor, which is dominated by the mutual competition between the intarlayer bond parameters R1 and R2, the indirect-direct bandgap tran- sition is proposed from the analysis of wavefunction. Once any more layer is added, multilayer arsenene are always direct bandgap semiconductors with bandgap in the order of 1 eV. Even more remarkable is that the intrinsic carrier mobility can reach as high as several thousand square cen- timeters per volt-second. All these make few-layer arsenene intriguing for devices applications in semiconducting industry.

  15. Schottky barriers at metal-finite semiconducting carbon nanotube interfaces

    OpenAIRE

    Xue, Yongqiang; Ratner, Mark A.

    2003-01-01

    Electronic properties of metal-finite semiconducting carbon nanotube interfaces are studied as a function of the nanotube length using a self-consistent tight-binding theory. We find that the shape of the potential barrier depends on the long-range tail of the charge transfer, leading to an injection barrier thickness comparable to half of the nanotube length until the nanotube reaches the bulk limit. The conductance of the nanotube junction shows a transition from tunneling to thermally-acti...

  16. TECHNOLOGICAL AND FUNCTIONAL PROPERTIES OF LACTIC ACID BACTERIA: THE IMPORTANCE OF THESE MICROORGANISMS FOR FOOD

    Directory of Open Access Journals (Sweden)

    Amanda de Souza Motta

    2015-12-01

    Full Text Available Eacters of coccus or rods Gram-positive, catalase negative, non-sporulating, which produce lactic acid as the major end product during the fermentation of carbohydrates. When applied on food, provides beneficial effects to consumers through its functional and technological properties. With this the present review article, explore the potential application of lactic acid bacteria in food. The following genera are considered the principal lactic acid bacteria: Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Oenococcus, Pediococcus, Streptococcus, Tetragenococcus, Vagococcus and Weissella. These cultures have been used as starter or adjunct cultures for the fermentation of foods and beverages due to their contributions to the sensorial characteristics of these products and by microbiological stability. Their probiotic properties have also been investigated. More recent studies by indigenous cultures have received increased attention in light of the search for isolated cultures of a given raw material and a certain region. These microorganisms are being investigated for its functional and technological potential that may be applied in product development with its own characteristics and designation of origin. Those properties will be discussed in the present review in order to highlight the performance of these bacteria and the high degree of control over the fermentation process and standardization of the final product. The use of autochthonous cultures will be considered due the increase of studies of new cultures of lactic acid bacteria isolated of milk and meat of distinct products.

  17. Display MTF measurements based on scanning and imaging technologies and its importance in the application space

    Science.gov (United States)

    Kaur, Balvinder; Olson, Jeff; Flug, Eric A.

    2016-05-01

    Measuring the Modulation Transfer Function (MTF) of a display monitor is necessary for many applications such as: modeling end-to-end systems, conducting perception experiments, and performing targeting tasks in real-word scenarios. The MTF of a display defines the resolution properties and quantifies how well the spatial frequencies are displayed on a monitor. Many researchers have developed methods to measure display MTFs using either scanning or imaging devices. In this paper, we first present methods to measure display MTFs using two separate technologies and then discuss the impact of a display MTF on a system's performance. The two measurement technologies were scanning with a photometer and imaging with a CMOS based camera. To estimate a true display MTF, measurements made with the photometer were backed out for the scanning optics aperture. The developed methods were applied to measure MTFs of the two types of monitors, Cathode Ray Tube (CRT) and Liquid Crystal Display (LCD). The accuracy of the measured MTFs was validated by comparing MTFs measured with the two systems. The methods presented here are simple and can be easily implemented employing either a Prichard photometer or an imaging device. In addition, the impact of a display MTF on the end-to-end performance of a system was modeled using NV-IPM.

  18. 77 FR 35057 - Importer of Controlled Substances; Notice of Registration; Rhodes Technologies

    Science.gov (United States)

    2012-06-12

    ... the company's physical security systems, verification of the company's compliance with state and local laws, and a review of the company's background and history. Therefore, pursuant to 21 U.S.C. 952(a) and...: Drug Schedule Opium, raw (9600) II Poppy Straw Concentrate (9670) II The company plans to import the...

  19. Effect of sulfur addition on the transport properties of semiconducting iron phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    El-Desoky, M.M. [Physics Department, Faculty of Science, Suez Canal University, Suez (Egypt); Ibrahim, F.A. [Department of Physics, Faculty of Education, Suez Canal University, Al-Arish (Egypt); Hassaan, M.Y. [Department of Physics, Faculty of Science, Al-Azhar University, Nasr City, 11884 Cairo (Egypt)

    2011-08-15

    The present paper focuses on a quantitative analysis of the metallic and semiconducting behavior of electrical resistivity in La{sub 0.91}Rb{sub 0.06}Mn{sub 0.94}O{sub 3} manganites. The contribution of inherent low-frequency acoustic phonons as well as high-frequency optical phonons, to the electron-phonon resistivity is estimated following Bloch-Gruneisen model. The computed phonon resistivity is compared with that of reported metallic resistivity, accordingly {rho}diff. [{rho}exp. - {l_brace}{rho}0 + {rho}e-ph (={rho}ac + {rho}op){r_brace}] have been analysed through electron-electron scattering. Also, the difference can be varies linearly with T{sup 4.5} in accordance with the electron-magnon scattering in the double exchange process. The results reveal important aspects transport mechanism as well as point out that it is not only dominated by electron-phonon scattering, but also by electron-electron and electron-magnon scattering process. Alternatively, in high temperature regime (T {>=} T{sub P}) the semiconducting nature is discussed with Mott's variable range hopping (VRH) and small polaron conduction (SPC) model. (authors)

  20. Synthesis and morphological modification of semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Valente, Jaime S., E-mail: jsanchez@imp.mx [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); López-Salinas, Esteban [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); Prince, Julia [Universidad Anáhuac México Norte, Av. Universidad Anáhuac # 46, Huixquilucan, Edo. de México 52786 (Mexico); González, Ignacio; Acevedo-Peña, Prospero [Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Apdo. Postal 55-534, 09340 México D.F. (Mexico); Ángel, Paz del [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico)

    2014-09-15

    Layered double hydroxide (LDH) thin films with different chemical compositions (MgZnAl, MgZnGa, MgGaAl) and varying thicknesses were easily prepared by sol–gel method followed by dip-coating. Films were chemically uniform, transparent and well adhered to a conductive indium tin oxide (ITO) substrate. Structure, chemical composition and morphology of the thin films were characterized by XRD-GADDS, SEM-EDS and AFM. Additionally, the semiconducting properties of all the prepared films were studied through the Mott–Schottky relationship; such properties were closely related to the chemical compositions of the film. The films were characterized after electrochemical treatment and important modifications regarding surface morphology, particle and crystal sizes were observed. An in-depth study was conducted in order to investigate the effect of several different electrochemical treatments on the morphology, particle size distribution and crystal size of LDH thin films. Upon electrochemical treatment, the films' surface became smooth and the particles forming the films were transformed from flaky open LDH platelets to uniformly distributed close-packed LDH nanoparticles. - Highlights: • Semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films prepared by sol–gel. • LDH thin films show a turbostratic morphology made up of porous flakes. • Electrochemical treatments change the flaky structure into a nanoparticle array.

  1. Synthesis, characterization, and transistor and solar cell applications of a naphthobisthiadiazole-based semiconducting polymer.

    Science.gov (United States)

    Osaka, Itaru; Shimawaki, Masafumi; Mori, Hiroki; Doi, Iori; Miyazaki, Eigo; Koganezawa, Tomoyuki; Takimiya, Kazuo

    2012-02-22

    We report the synthesis and characterization of a novel donor-acceptor semiconducting polymer bearing naphthobisthiadiazole (NTz), a doubly benzothiadiazole (BTz)-fused ring, and its applications to organic field-effect transistors and bulk heterojunction solar cells. With NTz's highly π-extended structure and strong electron affinity, the NTz-based polymer (PNTz4T) affords a smaller bandgap and a deeper HOMO level than the BTz-based polymer (PBTz4T). PNTz4T exhibits not only high field-effect mobilities of ~0.56 cm(2)/(V s) but also high photovoltaic properties with power conversion efficiencies of ~6.3%, both of which are significantly high compared to those for PBTz4T. This is most likely due to the more suitable electronic properties and, importantly, the more highly ordered structure of PNTz4T in the thin film than that of PBTz4T, which might originate in the different symmetry between the cores. NTz, with centrosymmetry, can lead to a more linear backbone in the present polymer system than BTz with axisymmetry, which might be favorable for better molecular ordering. These results demonstrate great promise for using NTz as a bulding unit for high-performance semiconducting polymers for both transistors and solar cells.

  2. Calculating charge-carrier mobilities in disordered semiconducting polymers: Mean field and beyond

    Science.gov (United States)

    Cottaar, J.; Bobbert, P. A.

    2006-09-01

    We model charge transport in disordered semiconducting polymers by hopping of charges on a regular cubic lattice of sites. A large on-site Coulomb repulsion prohibits double occupancy of the sites. Disorder is introduced by taking random site energies from a Gaussian distribution. Recently, it was demonstrated that this model leads to a dependence of the charge-carrier mobilities on the density of charge carriers that is in agreement with experimental observations. The model is conveniently solved within a mean-field approximation, in which the correlation between the occupational probabilities of different sites is neglected. This approximation becomes exact in the limit of vanishing charge-carrier densities, but needs to be checked at high densities. We perform this check by dividing the lattice in pairs of neighboring sites and taking into account the correlation between the sites within each pair explicitly. This pair approximation is expected to account for the most important corrections to the mean-field approximation. We study the effects of varying temperature, charge-carrier density, and electric field. We demonstrate that in the parameter regime relevant for semiconducting polymers used in practical devices the corrections to the mobilities calculated from the mean-field approximation will not exceed a few percent, so that this approximation can be safely used.

  3. STUDIES ON PAN MACROMOLECULAR SEMICONDUCTING FIBER 1. PREPARATION OF PAN CONDUCTING FIBER TREATED BY STANNIC CHLORIDE AND ITS SEMICONDUCTING BEHAVIOUR

    Institute of Scientific and Technical Information of China (English)

    WANG Dexi; CUI Dayuan; LUO Boliang; WANG Xiugang; WU Renjie

    1984-01-01

    The PAN fiber treated by Lewis acid (e.g. stannic chloride) could be transformed into a macromolecular conducting fiber by further thermal treatment. Depending on thermal treatment condition the resistance of the fiber varied from 103 to 1012 Ω and kept stable after hydrolysis. The fiber has enough strength to be processed by various means. This is a new kind of macromolecular semiconducting fiber having some characteristics similar to those of organic semiconductors.

  4. Importance of high-throughput cell separation technologies for genomics/proteomics-based clinical diagnostics

    Science.gov (United States)

    Leary, James F.; Szaniszlo, Peter; Prow, Tarl W.; Reece, Lisa M.; Wang, Nan; Asmuth, David M.

    2002-06-01

    Gene expression microarray analyses of mixtures of cells approximate a weighted average of the gene expression profiles (GEPs) of each cell type according to its relative abundance in the overall cell sample being analyzed. If the targeted subpopulation of cells is in the minority, or the expected perturbations are marginal, then such changes will be masked by the GEP of the normal/unaffected cells. We show that the GEP of a minor cell subpopulation is often lost when that cell subpopulation is of a frequency less than 30 percent. The GEP is almost always masked by the other cell subpopulations when that frequency drops to 10 percent or less. Several methodologies can be employed to enrich the target cells submitted for microarray analyses. These include magnetic sorting and laser capture microdissection. However, high-throughput flow cytometry/cell sorting overcomes many restrictions of experimental enrichment conditions. This technology can also be used to sort smaller numbers of cells of specific cell subpopulations and subsequently amplify their mRNAs before microarray analyses. When purification techniques are applied to unfixed samples, the potential for changes in gene levels during the process of collection is an additional concern. High-throughput cell separation technologies are needed that can process the necessary number of cells expeditiously in order to avoid such uncontrolled changes in the target cells GEP. In cases where even the use of HTS yields only a small number of cells, the mRNAs (after reverse transcription to cDNA's) must be amplified to yield enough material for conventional microarray analyses. However, the problem of using microamplification PCR methods to expand the amount of cDNAs (from mRNAs) is that it is very difficult to amplify equally all of the mRNAs. Unequal amplification leads to a distorted gene expression profile on the microarray. Linear amplifications is difficult to achieve. Unfortunately, present-day gene-chips need to

  5. The Application of Genomic Technologies to Investigate the Inheritance of Economically Important Traits in Goats

    Directory of Open Access Journals (Sweden)

    Marcel Amills

    2014-01-01

    Full Text Available Goat genomics has evolved at a low pace because of a lack of molecular tools and sufficient investment. Whilst thousands and hundreds of quantitative trait loci (QTL have been identified in cattle and sheep, respectively, about nine genome scans have been performed in goats dealing with traits as conformation, growth, fiber quality, resistance to nematodes, and milk yield and composition. In contrast, a great effort has been devoted to the characterization of candidate genes and their association with milk, meat, and reproduction phenotypes. In this regard, causal mutations have been identified in the αS1-casein gene that has a strong effect on milk composition and the PIS locus that is linked to intersexuality and polledness. In recent times, the development of massive parallel sequencing technologies has allowed to build a reference genome for goats as well as to monitor the expression of mRNAs and microRNAs in a broad array of tissues and experimental conditions. Besides, the recent design of a 52K SNP chip is expected to have a broad impact in the analysis of the genetic architecture of traits of economic interest as well as in the study of the population structure of goats at a worldwide scale.

  6. The Most Important Directions Of Development Of Technology Convergence And The Basic Scope Of Nanoproducts

    Directory of Open Access Journals (Sweden)

    Andrey Prigulnyy

    2012-06-01

    Full Text Available The author investigated the evolution of the process of production in a nanosphere, analyzes the features and achievements of production units of nanotechnology, nanomaterials and nano-products in various sectors of the Russian economy: electronics, medical and pharmacological industry, genetic engineering, production of construction materials, electric power industry. Considered sectoral and regional distribution of particular nanotechnologies and nanomaterials. Allocated Rupp leading countries of the nanospheres. As the proliferation of nanotechnology leaders selected USA, Japan, Germany and South Korea. In the next group of countries with high development of nanotechnology, with a lower level of activity states - Israel, Singapore, the Netherlands, Sweden and Switzerland. The next group consists of France, Britain and China, where the level exceeds the level of real nanoaktivnosti nanotechnology. Based on the Letter of the world and practice, the author of the nanotechnology sector is estimated to be the most attractive to venture capital. The problem lies in the expansion of the Russian practice of attracting foreign venture capital to fund research. One of the most realistic solution to this problem is in the framework of the strategy of cooperation between science, business and government, to accelerate the transition of technologies from laboratory to industrial nanomaterials from fragmentary studies to design innovation.

  7. Evaluation of High Energy Nuclear Data of Importance for Use in Accelerator and Space Technology

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ouk

    2005-10-15

    New evaluation were performed for neutron- and proton-induced reactions for energies up to 250 400 MeV on C-12, N-14, O-16, Al-27, Si-28, Ca-40, Ar-40, Fe-54,58, Ni-64, Cu-63,65, Zr-90, Pb-208, Th-232, U-233,234,236, and Cm-243246. The evaluated results are then applied to the accelerator and space technology. A set of optical model parameters were optimized by searching a number of adjustable coefficients with the Simulated Annealing(SA) method for the spherical nuclei. A parameterization of the empirical formula was proposed to describe the proton-nucleus non-elastic cross sections of high-priority elements for space shielding purpose for proton energies from reaction threshold up to 400 MeV, which was then implemented into the fast scoping space shielding code CHARGE, based on the results of the optical model analysis utilizing up-to-date measurements. For proton energies up to 400 MeV covering most of the incident spectrum for trapped protons and solar energetic particle events, energy-angle spectra of secondary neutrons produced from the proton-induced neutron production reaction were prepared. The evaluated cross section set was applied to the thick target yield (TTY) and promp radiation benchmarks for the accelerator shielding. As for the assessment of the radiological impact of the accelerator to the environment, relevant nuclear reaction cross sections for the activation of the air were recommended among the author's evaluations and existing library based on the available measurements.

  8. Investigation of the fungal community structures of imported wheat using high-throughput sequencing technology

    Science.gov (United States)

    Wang, Ying; Zhang, Guiming; Gao, Ruifang; Xiang, Caiyu; Feng, Jianjun; Lou, Dingfeng; Liu, Ying

    2017-01-01

    This study introduced the application of high-throughput sequencing techniques to the investigation of microbial diversity in the field of plant quarantine. It examined the microbial diversity of wheat imported into China, and established a bioinformatics database of wheat pathogens based on high-throughput sequencing results. This study analyzed the nuclear ribosomal internal transcribed spacer (ITS) region of fungi through Illumina Miseq sequencing to investigate the fungal communities of both seeds and sieve-through. A total of 758,129 fungal ITS sequences were obtained from ten samples collected from five batches of wheat imported from the USA. These sequences were classified into 2 different phyla, 15 classes, 33 orders, 41 families, or 78 genera, suggesting a high fungal diversity across samples. Apairwise analysis revealed that the diversity of the fungal community in the sieve-through is significantly higher than those in the seeds. Taxonomic analysis showed that at the class level, Dothideomycetes dominated in the seeds and Sordariomycetes dominated in the sieve-through. In all, this study revealed the fungal community composition in the seeds and sieve-through of the wheat, and identified key differences in the fungal community between the seeds and sieve-through. PMID:28241020

  9. Nonlinear terahertz devices utilizing semiconducting plasmonic metamaterials

    CERN Document Server

    Seren, Huseyin R; Keiser, George R; Maddox, Scott J; Zhao, Xiaoguang; Fan, Kebin; Bank, Seth R; Zhang, Xin; Averitt, Richard D

    2015-01-01

    The development of responsive metamaterials has enabled the realization of compact tunable photonic devices capable of manipulating the amplitude, polarization, wave vector, and frequency of light. Integration of semiconductors into the active regions of metallic resonators is a proven approach for creating nonlinear metamaterials through optoelectronic control of the semiconductor carrier density. Metal-free subwavelength resonant semiconductor structures offer an alternative approach to create dynamic metamaterials. We present InAs plasmonic disk arrays as a viable resonant metamaterial at terahertz frequencies. Importantly, InAs plasmonic disks exhibit a strong nonlinear response arising from electric field induced intervalley scattering resulting in a reduced carrier mobility thereby damping the plasmonic response. We demonstrate nonlinear perfect absorbers configured as either optical limiters or saturable absorbers, including flexible nonlinear absorbers achieved by transferring the disks to polyimide f...

  10. Technological regime of extraction, an important aid to exploiting natural gas deposits

    Energy Technology Data Exchange (ETDEWEB)

    Katzung, K.P.; Lenk, G.

    1967-02-01

    When planning the economic exploitation of gas reservoirs, it is important to determine as early as possible the constant rate of production and the length of time for which it can be sustained before a booster station must be provided to deliver the gas at the pressure required by the consumer. The following steps are recommended: (1) Determine the productive capacity by the back-pressure test or the isochronal test method. (2) Determine the productivity index and the production rate per well. (3) Calculate the decline of the reservoir pressure. (4) Calculate the cumulative production and the flowing bottomhole pressure as functions of times. (5) Caluculate the wellhead pressure as a function of time. The necessary formulas are given, and the calculations shown for a numerical example; the results are also plotted graphically.

  11. Process for separating metallic from semiconducting single-walled carbon nanotubes

    Science.gov (United States)

    Sun, Ya-Ping (Inventor)

    2008-01-01

    A method for separating semiconducting single-walled carbon nanotubes from metallic single-walled carbon nanotubes is disclosed. The method utilizes separation agents that preferentially associate with semiconducting nanotubes due to the electrical nature of the nanotubes. The separation agents are those that have a planar orientation, .pi.-electrons available for association with the surface of the nanotubes, and also include a soluble portion of the molecule. Following preferential association of the separation agent with the semiconducting nanotubes, the agent/nanotubes complex is soluble and can be solubilized with the solution enriched in semiconducting nanotubes while the residual solid is enriched in metallic nanotubes.

  12. Hop-Derived Prenylflavonoids and Their Importance in Brewing Technology – A Review

    Directory of Open Access Journals (Sweden)

    Elena Mudura

    2015-05-01

    Full Text Available Beer is one of the world’s most popular beverage products. Beer is all natural ingredients, so moderate consumption contributes to a healthy daily diet. Beer contains a large variety of phenolic compounds which are derived from the processed cereal (70% and hops (30% and which are responsible for the antioxidant activity of the beverage. Hops (Humulus lupulus L. are an essential ingredient of beer and are a source of polyphenols that contain the prenyl or geranyl group in the chemical structure, xanthohumol, isoxanthohumol, 6-prenilnaringenin and 8-prenylnaringenin. The prenylflavonoid's compounds found in beer have different biological activities demonstrated in vitro as antioxidant, anticarcinogenic, anti-inflammatory, estrogenic and antiviral. Important quantities of prenylflavonoids are lost during wort production. The losses may be explained by the low solubility of these compounds and its insufficient extraction in wort. Using appropriate engineering strategies, improvements in the recovery of prenylflavonoids from hops into beer has involved increased hopping rate, improved brewing process, especially wort boiling, increased colored malt yields and management of beer fermentations.Beer is one of the world’s most popular beverage products. Beer is all natural ingredients, so moderate consumption contributes to a healthy daily diet. Beer contains a large variety of phenolic compounds which are derived from the processed cereal (70% and hops (30% and which are responsible for the antioxidant activity of the beverage. Hops (Humulus lupulus L. are an essential ingredient of beer and are a source of polyphenols that contain the prenyl or geranyl group in the chemical structure, xanthohumol, isoxanthohumol, 6-prenilnaringenin and 8-prenylnaringenin. The prenylflavonoid's compounds found in beer have different biological activities demonstrated in vitro as antioxidant, anticarcinogenic, anti-inflammatory, estrogenic and antiviral. Important

  13. Unified Description of Charge-Carrier Mobilities in Disordered Semiconducting Polymers

    Science.gov (United States)

    Pasveer, W. F.; Cottaar, J.; Tanase, C.; Coehoorn, R.; Bobbert, P. A.; Blom, P. W.; de Leeuw, D. M.; Michels, M. A.

    2005-05-01

    From a numerical solution of the master equation for hopping transport in a disordered energy landscape with a Gaussian density of states, we determine the dependence of the charge-carrier mobility on temperature, carrier density, and electric field. Experimental current-voltage characteristics in devices based on semiconducting polymers are excellently reproduced with this unified description of the mobility. At room temperature it is mainly the dependence on carrier density that plays an important role, whereas at low temperatures and high fields the electric field dependence becomes important. Omission in the past of the carrier-density dependence has led to an underestimation of the hopping distance and the width of the density of states in these polymers.

  14. Fast-neutron capture cross sections of importance in technological applications. [Review

    Energy Technology Data Exchange (ETDEWEB)

    Poenitz, W. P.

    1979-01-01

    The importance of the capture cross section of the major fertile nuclei, /sup 238/U and /sup 232/Th, leads to the consideration of these data. The /sup 238/U (n,..gamma..) cross section is considered of priority as it is part of the /sup 238/U-/sup 239/Pu cycle. Experimental techniques used in the measurements of these data are considered. Data measured more recently are compared with provisions made for the possible explanations of differing results. It is concluded that the /sup 238/U (n,..gamma..) cross section is known with approx. 5% above 10 keV and fulfills the uncertainty limit for this cross section set to achieve design accuracy for k/sub eff/ and the breeding ratio above 500 keV. Below 500 keV, the present uncertainty falls short of the required 1.5 to 3.0% uncertainty. Specific recommendations are made to resolve existing discrepancies and data uncertainties. 84 references.

  15. Proazaphosphatranes: Versatile molecules with applications in fuel cell technology, biodiesel production and important organic transformations

    Science.gov (United States)

    Wadhwa, Kuldeep

    In recent years proazaphosphatranes of type P(RNCH2CH 2)3N have proven their synthetic utility as catalysts and as stoichiometric bases in a variety of organic transformations. Several reports from our group appeared in which the use of proazaphosphatranes for the activation of the silicon to synthesize useful organic intermediates. Herein we report the use of proazaphosphatranes to synthesize various useful small organic molecules by the activation of Si-O and Si-C bonds, along with efforts to gain evidence for silicon group activation. We previously demonstrated that a phosphatranium cation for which the counter anion is nitrate, is an excellent catalyst for aza- and thia-Michael reactions. Evidence was presented that such a nitrate salt in which the cation was bound to a solid support was superior to a commercially available nitrate anion exchange resin. These results prompted us to chemically bind phosphatranium salts to NafionRTM membrane supports to function as nitrate and hydroxide ion conducting membranes for fuel cell applications. Here we report the synthesis of a novel anion exchange fuel cell membrane by chemically attaching proazaphosphatranium and phosphatranium cations under microwave conditions to the sulfonic groups of Nafion-F RTM and the use of solid-state NMR techniques to determine the structure and composition of this anion exchange membrane. A thermally and air stable derivative of a proazaphosphatrane i.e., a benzyl azidoproazaphosphatrane, was discovered in our laboratory which was shown to be an excellent catalyst for biodiesel synthesis via the transesterification of soybean oil and for other Lewis base- catalyzed important organic transformations. However, the heterogeneous analog i.e., a Merrifield resin-bound azidoproazaphosphatrane, was found to be deactivated after 11 cycles for the transesterification of soybean oil. We report here an attempted synthesis of a TeflonRTM - and NafionRTM-bound azidoproazaphosphatrane. Such a solid

  16. Thermal Crosslinking of Organic Semiconducting Polythiophene Improves Transverse Hole Conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gearba, I.R.; Nam, C.-Y.; Pindak, R.; Black, C.T.

    2009-10-26

    Thermal crosslinking using a suitable radical initiator simultaneously improves electrical conductivity in the semiconducting polymer poly(3-hexylthiophene) and makes the material insoluble. Crosslinked polythiophene shows as much as a fivefold increase in hole conductivity across the film thickness without any shift in spectral light absorption. Grazing incidence x-ray diffraction reveals more in-plane polymer lamellae stacking with only a small decrease in film crystallinity. Improved transverse conductivity increases the performance of model planar solar cells by threefold, from 0.07% to 0.2%. The ability to render polythiophene insoluble without disrupting film structural order enables fabrication pathways to more complex device architectures.

  17. Thermal crosslinking of organic semiconducting polythiophene improves transverse hole conductivity

    Science.gov (United States)

    Gearba, Ioana R.; Nam, Chang-Yong; Pindak, Ron; Black, C. T.

    2009-10-01

    Thermal crosslinking using a suitable radical initiator simultaneously improves electrical conductivity in the semiconducting polymer poly(3-hexylthiophene) and makes the material insoluble. Crosslinked polythiophene shows as much as a fivefold increase in hole conductivity across the film thickness without any shift in spectral light absorption. Grazing incidence x-ray diffraction reveals more in-plane polymer lamellae stacking with only a small decrease in film crystallinity. Improved transverse conductivity increases the performance of model planar solar cells by threefold, from 0.07% to 0.2%. The ability to render polythiophene insoluble without disrupting film structural order enables fabrication pathways to more complex device architectures.

  18. Size effects in band gap bowing in nitride semiconducting alloys

    DEFF Research Database (Denmark)

    Gorczyca, I.; Suski, T.; Christensen, Niels Egede

    2011-01-01

    Chemical and size contributions to the band gap bowing of nitride semiconducting alloys (InxGa1-xN, InxAl1-xN, and AlxGa1-xN) are analyzed. It is shown that the band gap deformation potentials of the binary constituents determine the gap bowing in the ternary alloys. The particularly large gap bo...... bowing in In-containing nitride alloys can be explained by specific properties of InN, which do not follow trends observed in several other binaries....

  19. Atomically thin semiconducting layers and nanomembranes: a review

    Science.gov (United States)

    Dragoman, Mircea; Dragoman, Daniela; Tiginyanu, Ion

    2017-03-01

    This article reviews the main physical properties of atomically thin semiconductors and the electronic devices based on them. We start with graphene, describing its physical properties and growth methods, followed by a discussion of its electronic device applications. Then, transition metal dichalcogenides (TMDs) are analyzed as a prototype of atomically thin semiconductors, their physical properties, growth methods, and electronic devices are discussed in detail. Finally, non-layered semiconducting membranes with thicknesses ranging from a few nanometers to about 50 nm, and considered as counterparts of atomically thin semiconductors, are analyzed, and their applications presented.

  20. An Exploration of Neutron Detection in Semiconducting Boron Carbide

    Science.gov (United States)

    Hong, Nina

    The 3He supply problem in the U.S. has necessitated the search for alternatives for neutron detection. The neutron detection efficiency is a function of density, atomic composition, neutron absorption cross section, and thickness of the neutron capture material. The isotope 10B is one of only a handful of isotopes with a high neutron absorption cross section---3840 barns for thermal neutrons. So a boron carbide semiconductor represents a viable alternative to 3He. This dissertation provides an evaluation of the performance of semiconducting boron carbide neutron detectors grown by plasma enhance chemical vapor deposition (PECVD) in order to determine the advantages and drawbacks of these devices for neutron detection. Improved handling of the PECVD system has resulted in an extremely stable plasma, enabling deposition of thick films of semiconducting boron carbide. A variety of material and semiconducting characterization tools have been used to investigate the structure and electronic properties of boron carbide thin films, including X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, infrared/Raman spectroscopy, current-voltage measurements and capacitance-voltage measurements. Elemental concentrations in the boron carbide films have been obtained from Rutherford backscattering and elastic recoil detection analysis. Solid state neutron detection devices have been fabricated in the form of heterostructured p-n diodes, p-type boron carbide/n-type Si. Operating conditions, including applied bias voltage, and time constants, have been optimized for maximum detection efficiency and correlated to the semiconducting properties investigated in separate electronic measurements. Accurate measurements of the neutron detection efficiency and the response of the detector to a wide range of neutron wavelengths have been performed at a well calibrated, tightly collimated, "white" cold neutron beam source using time-of-flight neutron detection technique

  1. Enhanced Transverse Magnetoresistive Effect in Semiconducting Diamond Films

    Institute of Scientific and Technical Information of China (English)

    WANG Wan-Lu; LIAO Ke-Jun; WANG Bi-Ben

    2000-01-01

    A very large magnetoresistive effect in both homoepitaxial and heteroepitaxial semiconducting diamond films by chemical vapor deposition has been observed. The changes in the resistance of the films strongly depend on both magnetic field intensity and geometric form of the samples. The effect of disk structure is greater than that of stripe type samples, also variation in the resistance of homoepitaxial diamond films is greater than that of eteroepitaxial diamond films. The resistance of homoepitaxial diamond films with the disk structure is increased y a factor of 2.1 at room temperature under magnetic field intensity of 5 T, but only 0.80 for heteroepitaxial diamond films.

  2. Importance of the validation of saving technologies of electric power; Importancia de la validacion de tecnologias ahorradoras de energia electrica

    Energy Technology Data Exchange (ETDEWEB)

    Valer Negrete, Adrian [Programa de Ahorro de Energia del Sector Electrico (PAESE), Comision Federal de Electricidad (Mexico)

    2003-07-01

    Within the Programs of Energy Saving it is fundamental the search and application of new technologies, with which this saving can be obtained, selected with base in their technical characteristics that allow to reduce to the consumptions and demands of power, without damaging the electric networks nor the transformers of the Comision Federal de Electricidad. It is important that the investments which are made count on attractive periods of capital recovery, in comparison with the useful life of the product, reason why the knowledge and price of the new technologies will be parameters to consider in an important manner, creating the need of conducting tests that verify the veracity of the information of the supplier, resulting in certain cases, the change of design of these technologies, so that thus they fulfill the engaged characteristics. This paper indicates the characteristics that the new saving technologies of electrical energy must fulfill and the tests and parameters to consider their evaluation. [Spanish] Dentro de los Programas de Ahorro de Energia es fundamental la busqueda y aplicacion de nuevas tecnologias, con las que se pueda obtener dicho ahorro, seleccionadas con base en sus caracteristicas tecnicas que permitan reducir los consumos y demandas de potencia, sin danar las redes ni transformadores de la Comision Federal de Electricidad. Es importante que las inversiones que se realicen cuenten con periodos de recuperacion de capital atractivos, comparados con la vida util del producto, por lo que el conocimiento y precio de las nuevas tecnologias seran parametros a considerar de manera importante, creandose la necesidad de realizar pruebas que verifiquen la veracidad de la informacion del proveedor, resultando en determinados casos, el cambio de diseno de dichas tecnologias, para que asi cumplan las caracteristicas prometidas. Este trabajo indica las caracteristicas que deben cumplir las nuevas tecnologias ahorradoras de energia electrica y las

  3. THEORETICAL AND PRACTICAL CONSIDERATIONS REGARDING THE IMPORTANCE OF INVESTMENT IN TECHNOLOGY AND INFORMATION IN THE PROCESS OF ECONOMIC GROWTH

    Directory of Open Access Journals (Sweden)

    CEAUSESCU IONUT

    2013-02-01

    Full Text Available The main purpose of this study is to capture based on new theories of economic growth in the knowledge, based economic development, the importance of investing in information are as a new factor of production, we propose a different treatment of essential identifiable knowledge structures: technologies and information .. Meanwhile, the article aims to capture the role that information plays in this highly complex process of economic growth. I realized through this expose, a representation of specific investments in information behavior and reasoning phenomena sustainable development concepts.

  4. The Ways in which Technology Is Imported and Their Effects on Employment and Training--The Case of the Ivory Coast.

    Science.gov (United States)

    Kone, Zobila

    1984-01-01

    If education is to play a role in the design and implementation of a policy of technological development in the Ivory Coast, an educational policy is needed that aims at improving the country's ability to assimilate, adapt, and modify imported technologies and to produce new technologies locally. (RM)

  5. Phase Separation in Bulk Heterojunctions of Semiconducting Polymers and Fullerenes for Photovoltaics

    Science.gov (United States)

    Treat, Neil D.; Chabinyc, Michael L.

    2014-04-01

    Thin-film solar cells are an important source of renewable energy. The most efficient thin-film solar cells made with organic materials are blends of semiconducting polymers and fullerenes called the bulk heterojunction (BHJ). Efficient BHJs have a nanoscale phase-separated morphology that is formed during solution casting. This article reviews recent work to understand the nature of the phase-separation process resulting in the formation of the domains in polymer-fullerene BHJs. The BHJ is now viewed as a mixture of polymer-rich, fullerene-rich, and mixed polymer-fullerene domains. The formation of this structure can be understood through fundamental knowledge of polymer physics. The implications of this structure for charge transport and charge generation are given.

  6. Molecular Design of Semiconducting Polymers for High-Performance Organic Electrochemical Transistors

    KAUST Repository

    Nielsen, Christian B.

    2016-07-22

    The organic electrochemical transistor (OECT), capable of transducing small ionic fluxes into electronic signals in an aqueous envi-ronment, is an ideal device to utilize in bioelectronic applications. Currently, most OECTs are fabricated with commercially availa-ble conducting poly(3,4-ethylenedioxythiophene) (PEDOT)-based suspensions and are therefore operated in depletion mode. Here, we present a series of semiconducting polymers designed to elucidate important structure-property guidelines required for accumulation mode OECT operation. We discuss key aspects relating to OECT performance such as ion and hole transport, elec-trochromic properties, operational voltage and stability. The demonstration of our molecular design strategy is the fabrication of accumulation mode OECTs that clearly outperform state-of-the-art PEDOT based devices, and show stability under aqueous oper-ation without the need for formulation additives and cross-linkers.

  7. Molecular Design of Semiconducting Polymers for High-Performance Organic Electrochemical Transistors.

    Science.gov (United States)

    Nielsen, Christian B; Giovannitti, Alexander; Sbircea, Dan-Tiberiu; Bandiello, Enrico; Niazi, Muhammad R; Hanifi, David A; Sessolo, Michele; Amassian, Aram; Malliaras, George G; Rivnay, Jonathan; McCulloch, Iain

    2016-08-17

    The organic electrochemical transistor (OECT), capable of transducing small ionic fluxes into electronic signals in an aqueous environment, is an ideal device to utilize in bioelectronic applications. Currently, most OECTs are fabricated with commercially available conducting poly(3,4-ethylenedioxythiophene) (PEDOT)-based suspensions and are therefore operated in depletion mode. Here, we present a series of semiconducting polymers designed to elucidate important structure-property guidelines required for accumulation mode OECT operation. We discuss key aspects relating to OECT performance such as ion and hole transport, electrochromic properties, operational voltage, and stability. The demonstration of our molecular design strategy is the fabrication of accumulation mode OECTs that clearly outperform state-of-the-art PEDOT-based devices, and show stability under aqueous operation without the need for formulation additives and cross-linkers.

  8. A photodegradable hexaaza-pentacene molecule for selective dispersion of large-diameter semiconducting carbon nanotubes.

    Science.gov (United States)

    Han, Jie; Ji, Qiyan; Li, Hongbo; Li, Gang; Qiu, Song; Li, Hai-Bei; Zhang, Qichun; Jin, Hehua; Li, Qingwen; Zhang, Jin

    2016-06-08

    Harvesting high-purity semiconducting single-walled carbon nanotubes (s-SWCNTs) with removable dispersants remains a challenge. In this work, we demonstrate that small heteroacene derivatives may serve as promising selective dispersants for sorting s-SWCNTs. A rich N "doped" and thiophene-substituted hexaazapentacene molecule, denoted as 4HP, was found to be more favorable for high-purity s-SWCNTs with large diameters. Importantly, 4HP is photodegradable under 365 nm or blue light, which enables a simple deposition approach for the formation of clean s-SWCNT networks. The as-fabricated thin film transistors show excellent performance with a charge-mobility of 30-80 cm(2) V(-1) s(-1) and an on-off ratio of 10(4)-10(6).

  9. Development of high-performing semiconducting polymers for organic electrochemical transistors (Conference Presentation)

    Science.gov (United States)

    Nielsen, Christian

    2016-11-01

    The organic electrochemical transistor (OECT), capable of amplifying small electrical signals in an aqueous environment, is an ideal device to utilize in organic bioelectronic applications involving for example neural interfacing and diagnostics. Currently, most OECTs are fabricated with commercially available conducting poly(3,4-ethylenedioxythiophene)-based suspensions such as PEDOT:PSS and are therefore operated in depletion mode giving rise to devices that are permanently on with non-optimal operational voltage. With the aim to develop and utilize efficient accumulation mode OECT devices, we discuss here our recent results regarding the design, synthesis and performance of novel intrinsic semiconducting polymers. Covering key aspects such as ion and charge transport in the bulk semiconductor and operational voltage and stability of the materials and devices, we have elucidated important structure-property relationships. We illustrate the improvements this approach has afforded in the development of high performance accumulation mode OECT materials.

  10. Charge-carrier mobilities in disordered semiconducting polymers: effects of carrier density and electric field

    Science.gov (United States)

    Meisel, K. D.; Pasveer, W. F.; Cottaar, J.; Tanase, C.; Coehoorn, R.; Bobbert, P. A.; Blom, P. W. M.; de Leeuw, D. M.; Michels, M. A. J.

    2006-02-01

    We model charge transport in disordered semiconducting polymers by hopping of charge carriers on a square lattice of sites with Gaussian on-site energy disorder, using Fermi-Dirac statistics. From numerically exact solutions of the Master equation, we study the dependence of the charge-carrier mobility on temperature, carrier density, and electric field. Our results are used in calculating current-voltage characteristics of hole-only polymer diodes. It is found that very good fits to experimental current-voltage characteristics can be obtained at different temperatures, with reasonable fitting parameters for the width of the Gaussian density of states and the lattice constant. In agreement with the experiments we find that the density dependence is dominant over the field dependence. Only at high fields and low temperatures the field dependence becomes noticeable. The potential and current distribution show strong inhomogeneities, which may have important consequences for the operation of polymer opto-electronic devices.

  11. Surface-Mediated Solidification of a Semiconducting Polymer during Time-Controlled Spin-Coating.

    Science.gov (United States)

    Na, Jin Yeong; Kang, Boseok; Lee, Seung Goo; Cho, Kilwon; Park, Yeong Don

    2016-12-29

    Spin-casting a polymer semiconductor solution over a short period of only a few seconds dramatically improved the molecular ordering and charge transport properties of the resulting semiconductor thin films. In this process, it was quite important to halt spinning before the drying line propagation had begun. Here, we elucidated the effects of the substrate surface characteristics on the drying kinetics during spin-coating, systematically investigated the microstructural evolution during semiconducting polymer solidification, and evaluated the performances of the resulting polymer field-effect transistors. We demonstrated that the spin time required to enhance the molecular ordering and electrical properties of the polythiophene thin films was strongly correlated with the solidification onset time, which was altered by surface treatments introduced onto the substrate surfaces.

  12. Molecular Strategies for Morphology Control in Semiconducting Polymers for Optoelectronics.

    Science.gov (United States)

    Rahmanudin, Aiman; Sivula, Kevin

    2017-06-28

    Solution-processable semiconducting polymers have been explored over the last decades for their potential applications in inexpensively fabricated transistors, diodes and photovoltaic cells. However, a remaining challenge in the field is to control the solid-state self-assembly of polymer chains in thin films devices, as the aspects of (semi)crystallinity, grain boundaries, and chain entanglement can drastically affect intra-and inter-molecular charge transport/transfer and thus device performance. In this short review we examine how the aspects of molecular weight and chain rigidity affect solid-state self-assembly and highlight molecular engineering strategies to tune thin film morphology. Side chain engineering, flexibly linking conjugation segments, and block co-polymer strategies are specifically discussed with respect to their effect on field effect charge carrier mobility in transistors and power conversion efficiency in solar cells. Example systems are taken from recent literature including work from our laboratories to illustrate the potential of molecular engineering semiconducting polymers.

  13. Semi-conducting carbon nanotube as variable capacitor

    Science.gov (United States)

    Ozmaian, M.; Naghdabadi, R.

    2013-12-01

    This paper proposes a novel, one-part, variable capacitor, using semi-conducting carbon nanotube (CNT). This variable capacitor works based on the change in the electronic structure of CNTs under applied voltage and deformations. Positive and negative charges are stored at both ends of a non-zero band gap nanotube which works as metallic electrodes in parallel plate capacitors. Also the neutral strip in the middle acts as the dielectric part of a conventional capacitor under the influence of an external electric field. Mechanical strains on carbon nanotube change its band gap energy and thus the length of neutral strip and charged regions. The lengths of these parts are primarily dependent on the nanotube chirality, deformation mode and applied voltage. This way, different parts of a conventional cantilever, parallel plate or bridge capacitor are reduced to a one part semi-conducting CNT capacitor. Analytical calculations based on classical electrostatics and density of states (DOS) relations are employed to investigate the effect of CNTs geometry, applied voltage and deformations on capacitive features. The proposed CNT-variable-capacitor can be useful for nano-electromechanical systems (NEMS), including displacement measurement sensors and tunable capacitor in integrated circuits.

  14. Stacked mechanical nanogenerator comprising piezoelectric semiconducting nanostructures and Schottky conductive contacts

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhong L [Marietta, GA; Xu, Sheng [Atlanta, GA

    2011-08-23

    An electric power generator includes a first conductive layer, a plurality of semiconducting piezoelectric nanostructures, a second conductive layer and a plurality of conductive nanostructures. The first conductive layer has a first surface from which the semiconducting piezoelectric nanostructures extend. The second conductive layer has a second surface and is parallel to the first conductive layer so that the second surface faces the first surface of the first conductive layer. The conductive nanostructures depend downwardly therefrom. The second conductive layer is spaced apart from the first conductive layer at a distance so that when a force is applied, the semiconducting piezoelectric nanostructures engage the conductive nanostructures so that the piezoelectric nanostructures bend, thereby generating a potential difference across the at semiconducting piezoelectric nanostructures and also thereby forming a Schottky barrier between the semiconducting piezoelectric nanostructures and the conductive nanostructures.

  15. Foreign enterprises may enjoy income tax exemption on technology import%外国企业技术进口可减免企业所得税

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ China's State Administration of Taxation and the Ministry of Commerce recently released a circular further making clear the procedures on examining and approving applications for reduction and exemption of enterprise income tax on royalties involved in technology import, to encourage technology import and to standardise the procedures for tax reduction and exemprion.

  16. Nanoscale semiconducting silicon as a nutritional food additive

    Science.gov (United States)

    Canham, L. T.

    2007-05-01

    Very high surface area silicon powders can be realized by high energy milling or electrochemical etching techniques. Such nanoscale silicon structures, whilst biodegradable in the human gastrointestinal tract, are shown to be remarkably stable in most foodstuffs and beverages. The potential for using silicon to improve the shelf life and bioavailability of specific nutrients in functional foods is highlighted. Published drug delivery data implies that the nanoentrapment of hydrophobic nutrients will significantly improve their dissolution kinetics, through a combined effect of nanostructuring and solid state modification. Nutrients loaded to date include vitamins, fish oils, lycopene and coenzyme Q10. In addition, there is growing published evidence that optimized release of orthosilicic acid, the biodegradation product of semiconducting silicon in the gut, offers beneficial effects with regard bone health. The utility of nanoscale silicon in the nutritional field shows early promise and is worthy of much further study.

  17. Coexistence of negative photoconductivity and hysteresis in semiconducting graphene

    Science.gov (United States)

    Zhuang, Shendong; Chen, Yan; Xia, Yidong; Tang, Nujiang; Xu, Xiaoyong; Hu, Jingguo; Chen, Zhuo

    2016-04-01

    Solution-processed graphene quantum dots (GQDs) possess a moderate bandgap, which make them a promising candidate for optoelectronics devices. However, negative photoconductivity (NPC) and hysteresis that happen in the photoelectric conversion process could be harmful to performance of the GQDs-based devices. So far, their origins and relations have remained elusive. Here, we investigate experimentally the origins of the NPC and hysteresis in GQDs. By comparing the hysteresis and photoconductance of GQDs under different relative humidity conditions, we are able to demonstrate that NPC and hysteresis coexist in GQDs and both are attributed to the carrier trapping effect of surface adsorbed moisture. We also demonstrate that GQDs could exhibit positive photoconductivity with three-order-of-magnitude reduction of hysteresis after a drying process and a subsequent encapsulation. Considering the pervasive moisture adsorption, our results may pave the way for a commercialization of semiconducting graphene-based and diverse solution-based optoelectronic devices.

  18. Coexistence of negative photoconductivity and hysteresis in semiconducting graphene

    Directory of Open Access Journals (Sweden)

    Shendong Zhuang

    2016-04-01

    Full Text Available Solution-processed graphene quantum dots (GQDs possess a moderate bandgap, which make them a promising candidate for optoelectronics devices. However, negative photoconductivity (NPC and hysteresis that happen in the photoelectric conversion process could be harmful to performance of the GQDs-based devices. So far, their origins and relations have remained elusive. Here, we investigate experimentally the origins of the NPC and hysteresis in GQDs. By comparing the hysteresis and photoconductance of GQDs under different relative humidity conditions, we are able to demonstrate that NPC and hysteresis coexist in GQDs and both are attributed to the carrier trapping effect of surface adsorbed moisture. We also demonstrate that GQDs could exhibit positive photoconductivity with three-order-of-magnitude reduction of hysteresis after a drying process and a subsequent encapsulation. Considering the pervasive moisture adsorption, our results may pave the way for a commercialization of semiconducting graphene-based and diverse solution-based optoelectronic devices.

  19. Vertical semiconducting single-walled carbon nanotube Schottky diode

    Science.gov (United States)

    Jung, Sunghwan

    2014-07-01

    This paper presents a vertical semiconducting single-walled carbon nanotube (sSWCNT)-based Schottky device. For the first time, the author successfully demonstrated a vertical s-SWCNT Schottky diode on an anodized aluminum oxide (AAO) template. In the vertical pores of an AAO template s-SWCNTs were vertically grown and aligned. The vertical growth of s-SWCNTs inside the pores was achieved by successfully isolating the catalyst at the bottom of the pores by using redeposition enabled angled ion milling. The ends of the grown s-SWCNTs were coated with palladium and titanium to form Schottky and Ohmic contacts, respectively. The I-V characteristics of the vertical s-SWCNT paths engaging the Schottky and Ohmic contacts well demonstrated Schottky diode rectification.

  20. Nanoscale semiconducting silicon as a nutritional food additive

    Energy Technology Data Exchange (ETDEWEB)

    Canham, L T [pSiNutria Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ (United Kingdom)

    2007-05-09

    Very high surface area silicon powders can be realized by high energy milling or electrochemical etching techniques. Such nanoscale silicon structures, whilst biodegradable in the human gastrointestinal tract, are shown to be remarkably stable in most foodstuffs and beverages. The potential for using silicon to improve the shelf life and bioavailability of specific nutrients in functional foods is highlighted. Published drug delivery data implies that the nanoentrapment of hydrophobic nutrients will significantly improve their dissolution kinetics, through a combined effect of nanostructuring and solid state modification. Nutrients loaded to date include vitamins, fish oils, lycopene and coenzyme Q10. In addition, there is growing published evidence that optimized release of orthosilicic acid, the biodegradation product of semiconducting silicon in the gut, offers beneficial effects with regard bone health. The utility of nanoscale silicon in the nutritional field shows early promise and is worthy of much further study.

  1. Intercalation and Stability of Layered Semiconductive Material in Corrosive Environment

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The intercalation of 4-methyl pyridine (4-picoline) into layered semiconductive material (MnPS3) and the stability of the resulting materials in corrosive environments (water, HCI and open atmosphere) were investigated.Powder X-ray diffraction (XRD) indicated that the presence of water and hydrochloric acid greatly influenced the existing form of intercalation and its orientation in the interlayer of the host. Atmospheric environment (open air) affected the guest orientation in the interlayer of the host material. Phase transformation occurred and the material was stable. The intercalated compounds could be indexed in the trigonal unit cell. The XRD patterns exhibited sharp hkl reflections of the intercalated compounds, which formed in water and HCI,confirming that the materials were well crystalline and stable in corrosive environments.

  2. Semiconducting of nanocrystalline tin oxide and its influence factors

    Institute of Scientific and Technical Information of China (English)

    LI Li-li; DUAN Xue-chen

    2005-01-01

    A series of nanocrystalline SnO2 powders, doped with different Sb contents, were synthesized by route of alkoxides hydrolysis using SnCl4·5H2O and SbCl3 as starting materials and calcined at different temperatures. The microstructure and morphology of samples are investigated by XRD and TEM, the valence state changes of Sb in SnO2 crystal lattice is detected by M(O)ssbauer spectroscopy and XPS.The resistivity of powders is examined with a mould of inside diameter d=10mm at a constant pressure. The results show that lightly-doping Sb is effective means of semiconducting of nanocrystalline SnO2. The ratio of Sb5+ to Sb3+ decreases with increasing Sb content in SnO2 crystal lattices and calcination temperature. The XPS diffraction confirms the same result as Mssbauer spectroscopy.

  3. Semiconductivity in YBa2 - xSrxCu3Oy

    Science.gov (United States)

    Uluǧ, A.; Uluǧ, B.; Şener, E.

    1996-08-01

    Structural and electrical properties of YBa2-xSrxCu3Oy prepared under ambient oxygen pressure were systematically investigated for 0≤x≤2.0. Samples with high Sr contents, x≥1.7, showed semiconductive properties with an activation energy of ˜150 meV at high temperature, T≥80 K. At low temperatures, T≤80 K, activation energy dropped to ˜3.00 and ˜0.85 meV for x=1.7-1.8 and x=1.9-2.0, respectively. It is argued that YSr2Cu3Oy is likely to have a tetragonal structure and that the disorder introduced by Sr substitution affects electrical conduction, which involves charge hopping between the CuO chains at high Sr contents.

  4. Activated singlet exciton fission in a semiconducting polymer.

    Science.gov (United States)

    Musser, Andrew J; Al-Hashimi, Mohammed; Maiuri, Margherita; Brida, Daniele; Heeney, Martin; Cerullo, Giulio; Friend, Richard H; Clark, Jenny

    2013-08-28

    Singlet exciton fission is a spin-allowed process to generate two triplet excitons from a single absorbed photon. This phenomenon offers great potential in organic photovoltaics, but the mechanism remains poorly understood. Most reports to date have addressed intermolecular fission within small-molecular crystals. However, through appropriate chemical design chromophores capable of intramolecular fission can also be produced. Here we directly observe sub-100 fs activated singlet fission in a semiconducting poly(thienylenevinylene). We demonstrate that fission proceeds directly from the initial 1Bu exciton, contrary to current models that involve the lower-lying 2Ag exciton. In solution, the generated triplet pairs rapidly recombine and decay through the 2Ag state. In films, exciton diffusion breaks this symmetry and we observe long-lived triplets which form charge-transfer states in photovoltaic blends.

  5. Scalable Fabrication of 2D Semiconducting Crystals for Future Electronics

    Directory of Open Access Journals (Sweden)

    Jiantong Li

    2015-12-01

    Full Text Available Two-dimensional (2D layered materials are anticipated to be promising for future electronics. However, their electronic applications are severely restricted by the availability of such materials with high quality and at a large scale. In this review, we introduce systematically versatile scalable synthesis techniques in the literature for high-crystallinity large-area 2D semiconducting materials, especially transition metal dichalcogenides, and 2D material-based advanced structures, such as 2D alloys, 2D heterostructures and 2D material devices engineered at the wafer scale. Systematic comparison among different techniques is conducted with respect to device performance. The present status and the perspective for future electronics are discussed.

  6. Quantum Capacitance Modifies Interionic Interactions in Semiconducting Nanopores

    CERN Document Server

    Lee, Alpha A; Goriely, Alain

    2016-01-01

    Nanopores made with low dimensional semiconducting materials, such as carbon nanotubes and graphene slit pores, are used in supercapacitors. In theories and simulations of their operation, it is often assumed that such pores screen ion-ion interactions like metallic pores, i.e. that screening leads to an exponential decay of the interaction potential with ion separation. By introducing a quantum capacitance that accounts for the density of states in the material, we show that ion-ion interactions in carbon nanotubes and graphene slit pores actually decay algebraically with ion separation. This result suggests a new avenue of capacitance optimization based on tuning the electronic structure of a pore: a marked enhancement in capacitance might be achieved by developing nanopores made with metallic materials or bulk semimetallic materials.

  7. Amplified Spontaneous Emission Properties of Semiconducting Organic Materials

    Directory of Open Access Journals (Sweden)

    Eva M. Calzado

    2010-06-01

    Full Text Available This paper aims to review the recent advances achieved in the field of organic solid-state lasers with respect to the usage of semiconducting organic molecules and oligomers in the form of thin films as active laser media. We mainly focus on the work performed in the last few years by our research group. The amplified spontaneous emission (ASE properties, by optical pump, of various types of molecules doped into polystyrene films in waveguide configuration, are described. The various systems investigated include N,N´-bis(3-methylphenyl-N,N´-diphenylbenzidine (TPD, several perilenediimide derivatives (PDIs, as well as two oligo-phenylenevinylene derivatives. The ASE characteristics, i.e., threshold, emission wavelength, linewidth, and photostability are compared with that of other molecular materials investigated in the literature.

  8. Amplified spontaneous emission properties of semiconducting organic materials.

    Science.gov (United States)

    Calzado, Eva M; Boj, Pedro G; Díaz-García, María A

    2010-06-18

    This paper aims to review the recent advances achieved in the field of organic solid-state lasers with respect to the usage of semiconducting organic molecules and oligomers in the form of thin films as active laser media. We mainly focus on the work performed in the last few years by our research group. The amplified spontaneous emission (ASE) properties, by optical pump, of various types of molecules doped into polystyrene films in waveguide configuration, are described. The various systems investigated include N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD), several perilenediimide derivatives (PDIs), as well as two oligo-phenylenevinylene derivatives. The ASE characteristics, i.e., threshold, emission wavelength, linewidth, and photostability are compared with that of other molecular materials investigated in the literature.

  9. Substrate-induced Band Gap Renormalization in Semiconducting Carbon Nanotubes

    Science.gov (United States)

    Lanzillo, Nicholas A.; Kharche, Neerav; Nayak, Saroj K.

    2014-01-01

    The quasiparticle band gaps of semiconducting carbon nanotubes (CNTs) supported on a weakly-interacting hexagonal boron nitride (h-BN) substrate are computed using density functional theory and the GW Approximation. We find that the direct band gaps of the (7,0), (8,0) and (10,0) carbon nanotubes are renormalized to smaller values in the presence of the dielectric h-BN substrate. The decrease in the band gap is the result of a polarization-induced screening effect, which alters the correlation energy of the frontier CNT orbitals and stabilizes valence band maximum and conduction band minimum. The value of the band gap renormalization is on the order of 0.25 to 0.5 eV in each case. Accounting for polarization-induced band gap changes is crucial in comparing computed values with experiment, since nanotubes are almost always grown on substrates. PMID:24402238

  10. Semiconducting boron carbides with better charge extraction through the addition of pyridine moieties

    Science.gov (United States)

    Echeverria, Elena; Dong, Bin; Peterson, George; Silva, Joseph P.; Wilson, Ethiyal R.; Sky Driver, M.; Jun, Young-Si; Stucky, Galen D.; Knight, Sean; Hofmann, Tino; Han, Zhong-Kang; Shao, Nan; Gao, Yi; Mei, Wai-Ning; Nastasi, Michael; Dowben, Peter A.; Kelber, Jeffry A.

    2016-09-01

    The plasma-enhanced chemical vapor (PECVD) co-deposition of pyridine and 1,2 dicarbadodecaborane, 1,2-B10C2H12 (orthocarborane) results in semiconducting boron carbide composite films with a significantly better charge extraction than plasma-enhanced chemical vapor deposited semiconducting boron carbide synthesized from orthocarborane alone. The PECVD pyridine/orthocarborane based semiconducting boron carbide composites, with pyridine/orthocarborane ratios ~3:1 or 9:1 exhibit indirect band gaps of 1.8 eV or 1.6 eV, respectively. These energies are less than the corresponding exciton energies of 2.0 eV-2.1 eV. The capacitance/voltage and current/voltage measurements indicate the hole carrier lifetimes for PECVD pyridine/orthocarborane based semiconducting boron carbide composites (3:1) films of ~350 µs compared to values of  ⩽35 µs for the PECVD semiconducting boron carbide films fabricated without pyridine. The hole carrier lifetime values are significantly longer than the initial exciton decay times in the region of ~0.05 ns and 0.27 ns for PECVD semiconducting boron carbide films with and without pyridine, respectively, as suggested by the time-resolved photoluminescence. These data indicate enhanced electron-hole separation and charge carrier lifetimes in PECVD pyridine/orthocarborane based semiconducting boron carbide and are consistent with the results of zero bias neutron voltaic measurements indicating significantly enhanced charge collection efficiency.

  11. Prolonging charge separation in P3HT-SWNT composites using highly enriched semiconducting nanotubes.

    Science.gov (United States)

    Holt, Josh M; Ferguson, Andrew J; Kopidakis, Nikos; Larsen, Brian A; Bult, Justin; Rumbles, Garry; Blackburn, Jeffrey L

    2010-11-10

    Single-walled carbon nanotubes (SWNTs) have potential as electron acceptors in organic photovoltaics (OPVs), but the currently low-power conversion efficiencies of devices remain largely unexplained. We demonstrate effective redispersion of isolated, highly enriched semiconducting and metallic SWNTs into poly(3-hexylthiophene) (P3HT). We use these enriched blends to provide the first experimental evidence of the negative impact of metallic nanotubes. Time-resolved microwave conductivity reveals that the long-lived carrier population can be significantly increased by incorporating highly enriched semiconducting SWNTs into semiconducting polymer composites.

  12. Electronic structure and quantum transport properties of metallic and semiconducting nanowires

    Science.gov (United States)

    Simbeck, Adam J.

    The future of the semiconductor industry hinges upon new developments to combat the scaling issues that currently afflict two main chip components: transistors and interconnects. For transistors this means investigating suitable materials to replace silicon for both the insulating gate and the semiconducting channel in order to maintain device performance with decreasing size. For interconnects this equates to overcoming the challenges associated with copper when the wire dimensions approach the confinement limit, as well as continuing to develop low-k dielectric materials that can assure minimal cross-talk between lines. In addition, such challenges make it increasingly clear that device design must move from a top-down to a bottom-up approach in which the desired electronic characteristics are tailored from first-principles. It is with such fundamental hurdles in mind that ab initio calculations on the electronic and quantum transport properties of nanoscale metallic and semiconducting wires have been performed. More specifically, this study seeks to elaborate on the role played by confinement, contacts, dielectric environment, edge decoration, and defects in altering the electronic and transport characteristics of such systems. As experiments continue to achieve better control over the synthesis and design of nanowires, these results are expected to become increasingly more important for not only the interpretation of electronic and transport trends, but also in engineering the electronic structure of nanowires for the needs of the devices of the future. For the metallic atomic wires, the quantum transport properties are first investigated by considering finite, single-atom chains of aluminum, copper, gold, and silver sandwiched between gold contacts. Non-equilibrium Green's function based transport calculations reveal that even in the presence of the contact the conductivity of atomic-scale aluminum is greater than that of the other metals considered. This is

  13. 31 CFR 545.505 - Importation of goods, software, or technology exported from the territory of Afghanistan...

    Science.gov (United States)

    2010-07-01

    ... technology exported from the territory of Afghanistan controlled by the Taliban prior to July 6, 1999. 545... technology exported from the territory of Afghanistan controlled by the Taliban prior to July 6, 1999. (a... technology from the territory of Afghanistan controlled by the Taliban is authorized provided that: (1)...

  14. Study of organic-inorganic hetero-interfaces and electrical transport in semiconducting nanostructures

    Science.gov (United States)

    Wagner, Sean Robert

    As the electronics industry continues to evolve and move towards functional electronic devices with increasing complexity and functionality, it becomes important to explore materials outside the regime of conventional semiconductors. Organic semiconducting small molecules have received a large amount of attention due to their high degree of flexibility, the option to perform molecular synthesis to modify their electronic and magnetic properties, and their ability to organize into highly-ordered functionalized nanostructures and thin films. Being able to form complex nanostructures and thin films with molecular precision, while maintaining the ability to tune properties through modifications in the molecular chemistry could result in vast improvements in conventional device architectures. However, before this is realized, there still remains a significant lack of understanding regarding how these molecules interact with various substrate surfaces as well as their intermolecular interactions. The interplay between these interactions can produce drastic changes in the molecular orientation and ordering at the hetero-interface, which can affect the transport properties of the molecular thin film and ultimately modify the performance of the organic electronic device. This study first focuses on the growth dynamics, molecular ordering, and molecular orientation of metal phthalocyanine (MPc) molecules, particularly on Si, a substrate which is notoriously difficult to form an organized organic thin film on due to the surface dangling bonds. By deactivating these bonds, the formation of a highly ordered organic molecular thin film becomes possible. Combining scanning tunneling microscopy, scanning tunneling spectroscopy, low-energy electron diffraction, and density functional theory calculations, the growth evolution of MPc molecules ( M = Zn, Cu, Co) from the single molecule level to multilayered films on the deactivated Si(111)-B surface is investigated. Initial tests are

  15. Study of rigidity of semiconducting vanadate glasses and its importance in use of coatings

    Indian Academy of Sciences (India)

    Yasser B Saddeek; M S Gaafar

    2014-05-01

    The elastic moduli of some multicomponent vanadate based glasses were analysed in terms of the bond compression model by some physical parameters such as, the density, average stretching force constant and average atomic ring size. These parameters were calculated for all the glass series and for all the glass composition to estimate the rigidity of these glasses. The results showed that the average force constant and the elastic moduli of these glasses are sensitive to the decrease in PbO content. This behaviour was attributed to the increase in the molar volume and the role of different modifiers. These parameters along with the coordination number of the glasses affect the glass transition temperature. The correlation between the elastic moduli and thermal properties of these samples showed that 0.25MoO3–0.25PbO–0.5V2O5 glass is the most rigid and has an applicable glass transition temperature for coating.

  16. Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes into Dense, Aligned Rafts

    CERN Document Server

    Wu, Justin; Antaris, Alexander; Choi, Charina L; Xie, Liming; Wu, Yingpeng; Diao, Shuo; Chen, Changxin; Chen, Yongsheng; Dai, Hongjie

    2013-01-01

    Single-walled carbon nanotubes are promising nanoelectronic materials but face long-standing challenges including production of pure semiconducting SWNTs and integration into ordered structures. Here, highly pure semiconducting single-walled carbon nanotubes are separated from bulk materials and self-assembled into densely aligned rafts driven by depletion attraction forces. Microscopy and spectroscopy revealed a high degree of alignment and a high packing density of ~100 tubes/micron within SWNT rafts. Field-effect transistors made from aligned SWNT rafts afforded short channel (~150 nm long) devices comprised of tens of purely semiconducting SWNTs derived from chemical separation within a < 1 micron channel width, achieving unprecedented high on-currents (up to ~120 microamperes per device) with high on/off ratios. The average on-current was ~ 3-4 microamperes per tube. The results demonstrated densely aligned high quality semiconducting SWNTs for integration into high performance nanoelectronics.

  17. Structural Distortion Stabilizing the Antiferromagnetic and Semiconducting Ground State of BaMn2As2

    Directory of Open Access Journals (Sweden)

    Ekkehard Krüger

    2016-09-01

    Full Text Available We report evidence that the experimentally found antiferromagnetic structure as well as the semiconducting ground state of BaMn 2 As 2 are caused by optimally-localized Wannier states of special symmetry existing at the Fermi level of BaMn 2 As 2 . In addition, we find that a (small tetragonal distortion of the crystal is required to stabilize the antiferromagnetic semiconducting state. To our knowledge, this distortion has not yet been established experimentally.

  18. Below-gap excitation of semiconducting single-wall carbon nanotubes.

    Science.gov (United States)

    Soavi, G; Grupp, A; Budweg, A; Scotognella, F; Hefner, T; Hertel, T; Lanzani, G; Leitenstorfer, A; Cerullo, G; Brida, D

    2015-11-21

    We investigate the optoelectronic properties of the semiconducting (6,5) species of single-walled carbon nanotubes by measuring ultrafast transient transmission changes with 20 fs time resolution. We demonstrate that photons with energy below the lowest exciton resonance efficiently lead to linear excitation of electronic states. This finding challenges the established picture of a vanishing optical absorption below the fundamental excitonic resonance. Our result points towards below-gap electronic states as an intrinsic property of semiconducting nanotubes.

  19. Innovation in Information Technology: Theoretical and Empirical Study in SMQR Section of Export Import in Automotive Industry

    Science.gov (United States)

    Edi Nugroho Soebandrija, Khristian; Pratama, Yogi

    2014-03-01

    This paper has the objective to provide the innovation in information technology in both theoretical and empirical study. Precisely, both aspects relate to the Shortage Mispacking Quality Report (SMQR) Claims in Export and Import in Automotive Industry. This paper discusses the major aspects of Innovation, Information Technology, Performance and Competitive Advantage. Furthermore, In the empirical study of PT. Astra Honda Motor (AHM) refers to SMQR Claims, Communication Systems, Analysis and Design Systems. Briefly both aspects of the major aspects and its empirical study are discussed in the Introduction Session. Furthermore, the more detail discussion is conducted in the related aspects in other sessions of this paper, in particular in Literature Review in term classical and updated reference of current research. The increases of SMQR claim and communication problem at PT. Astra Daihatsu Motor (PT. ADM) which still using the email cause the time of claim settlement become longer and finally it causes the rejected of SMQR claim by supplier. With presence of this problem then performed to design the integrated communication system to manage the communication process of SMQR claim between PT. ADM with supplier. The systems was analyzed and designed is expected to facilitate the claim communication process so that can be run in accordance with the procedure and fulfill the target of claim settlement time and also eliminate the difficulties and problems on the previous manual communication system with the email. The design process of the system using the approach of system development life cycle method by Kendall & Kendall (2006)which design process covers the SMQR problem communication process, judgment process by the supplier, claim process, claim payment process and claim monitoring process. After getting the appropriate system designs for managing the SMQR claim, furthermore performed the system implementation and can be seen the improvement in claim communication

  20. Innovation in Information Technology: Theoretical and Empirical Study in SMQR Section of Export Import in Automotive Industry

    Directory of Open Access Journals (Sweden)

    Soebandrija Khristian Edi Nugroho

    2014-03-01

    Full Text Available This paper has the objective to provide the innovation in information technology in both theoretical and empirical study. Precisely, both aspects relate to the Shortage Mispacking Quality Report (SMQR Claims in Export and Import in Automotive Industry. This paper discusses the major aspects of Innovation, Information Technology, Performance and Competitive Advantage. Furthermore, In the empirical study of PT. Astra Honda Motor (AHM refers to SMQR Claims, Communication Systems, Analysis and Design Systems. Briefly both aspects of the major aspects and its empirical study are discussed in the Introduction Session. Furthermore, the more detail discussion is conducted in the related aspects in other sessions of this paper, in particular in Literature Review in term classical and updated reference of current research. The increases of SMQR claim and communication problem at PT. Astra Daihatsu Motor (PT. ADM which still using the email cause the time of claim settlement become longer and finally it causes the rejected of SMQR claim by supplier. With presence of this problem then performed to design the integrated communication system to manage the communication process of SMQR claim between PT. ADM with supplier. The systems was analyzed and designed is expected to facilitate the claim communication process so that can be run in accordance with the procedure and fulfill the target of claim settlement time and also eliminate the difficulties and problems on the previous manual communication system with the email. The design process of the system using the approach of system development life cycle method by Kendall & Kendall (2006which design process covers the SMQR problem communication process, judgment process by the supplier, claim process, claim payment process and claim monitoring process. After getting the appropriate system designs for managing the SMQR claim, furthermore performed the system implementation and can be seen the improvement in

  1. Semiconductive Nanostructures - Materials for Spinelectronics: New Data Bank Requirement

    Directory of Open Access Journals (Sweden)

    Paata J Kervalishvili

    2007-12-01

    Full Text Available Nanoscience, the interdisciplinary science that draws on physics, chemistry, biology, and computational mathematics, is still in its infancy. Control and manipulation on a nanometric scale allow the fabrication of nanostructures, the properties of which are mainly determined by quantum mechanics and differ considerably from that of the common crystalline state. Nanostructures constructed from inorganic solids such as semiconductors have new electronic and optical properties because of their size and quantization effects [1, 2]. The quantization effects reflect the fundamental characteristics of structures as soon as their size falls below a certain limit. An example of the simplest nanostructure is the quantum dot formed from the energy well of certain semiconductor materials with 5-10nm thickness sandwiched between other semiconductors with normal properties. Quantum dots, for example, have led to important novel technology for lasers, optical sensors, and other electronic devices. The application of nanolayers to data storage, switching, lighting, and other devices can lead to substantially new hardware, for example, energy cells, and eventually to the quantum-based internet. Nanoscience and nanotechnology encompass the development of nano-spinelectronics, spinelectronics materials production, and nano-spinelectronic measuring devices and technologies. Nano-spinelectronics, based on usage of magnetic semiconductors, represents a new and emerging area of science and engineering of the 21st century. It is a primary example of the creation and enhancement of new materials and devices for information technologies, operating with charge and spin degrees of freedom of carriers, free from present-day limitations. This new multi-disciplinary direction of science and technology is very much in need of support from new data banks, which will function as a source of new ideas and approaches.

  2. Dissociating excitons photogenerated in semiconducting carbon nanotubes at polymeric photovoltaic heterojunction interfaces.

    Science.gov (United States)

    Bindl, Dominick J; Safron, Nathaniel S; Arnold, Michael S

    2010-10-26

    Semiconducting single-walled carbon nanotubes (s-SWCNTs) have strong near-infrared and visible absorptivity and exceptional charge transport characteristics, rendering them highly attractive semiconductor absorbers for photovoltaic and photodetector technologies. However, these applications are limited by a poor understanding of how photogenerated charges, which are bound as excitons in s-SWCNTs, can be dissociated in large-area solid-state devices. Here, we measure the dissociation of excitons in s-SWCNT thin films that form planar heterojunction interfaces with polymeric photovoltaic materials using an exciton dissociation-sensitive photocapacitor measurement technique that is advantageously insensitive to optically induced thermal photoconductive effects. We find that fullerene and polythiophene derivatives induce exciton dissociation, resulting in electron and hole transfer, respectively, away from optically excited s-SWCNTs. Significantly weaker or no charge transfer is observed using wider gap polymers due to insufficient energy offsets. These results are expected to critically guide the development of thin film s-SWCNT-based photosensitive devices.

  3. Charge Transport in Two-Photon Semiconducting Structures for Solar Fuels.

    Science.gov (United States)

    Liu, Guohua; Du, Kang; Haussener, Sophia; Wang, Kaiying

    2016-10-20

    Semiconducting heterostructures are emerging as promising light absorbers and offer effective electron-hole separation to drive solar chemistry. This technology relies on semiconductor composites or photoelectrodes that work in the presence of a redox mediator and that create cascade junctions to promote surface catalytic reactions. Rational tuning of their structures and compositions is crucial to fully exploit their functionality. In this review, we describe the possibilities of applying the two-photon concept to the field of solar fuels. A wide range of strategies including the indirect combination of two semiconductors by a redox couple, direct coupling of two semiconductors, multicomponent structures with a conductive mediator, related photoelectrodes, as well as two-photon cells are discussed for light energy harvesting and charge transport. Examples of charge extraction models from the literature are summarized to understand the mechanism of interfacial carrier dynamics and to rationalize experimental observations. We focus on a working principle of the constituent components and linking the photosynthetic activity with the proposed models. This work gives a new perspective on artificial photosynthesis by taking simultaneous advantages of photon absorption and charge transfer, outlining an encouraging roadmap towards solar fuels.

  4. Boosting photoresponse in silicon metal-semiconductor-metal photodetector using semiconducting quantum dots

    Science.gov (United States)

    Biswas, Chandan; Kim, Yonghwan; Lee, Young Hee

    2016-11-01

    Silicon based metal-semiconductor-metal (MSM) photodetectors have faster photogeneration and carrier collection across the metal-semiconductor Schottky contacts, and CMOS integratibility compared to conventional p-n junction photodetectors. However, its operations are limited by low photogeneration, inefficient carrier-separation, and low mobility. Here, we show a simple and highly effective approach for boosting Si MSM photodetector efficiency by uniformly decorating semiconducting CdSe quantum dots on Si channel (Si-QD). Significantly higher photocurrent on/off ratio was achieved up to over 500 compared to conventional Si MSM photodetector (on/off ratio ~5) by increasing photogeneration and improving carrier separation. Furthermore, a substrate-biasing technique invoked wide range of tunable photocurrent on/off ratio in Si-QD photodetector (ranging from 2.7 to 562) by applying suitable combinations of source-drain and substrate biasing conditions. Strong photogeneration and carrier separation were achieved by employing Stark effect into the Si-QD hybrid system. These results highlight a promising method for enhancing Si MSM photodetector efficiency more than 100 times and simultaneously compatible with current silicon technologies.

  5. Failure mechanisms and electromechanical coupling in semiconducting nanowires

    Directory of Open Access Journals (Sweden)

    Peng B.

    2010-06-01

    Full Text Available One dimensional nanostructures, like nanowires and nanotubes, are increasingly being researched for the development of next generation devices like logic gates, transistors, and solar cells. In particular, semiconducting nanowires with a nonsymmetric wurtzitic crystal structure, such as zinc oxide (ZnO and gallium nitride (GaN, have drawn immense research interests due to their electromechanical coupling. The designing of the future nanowire-based devices requires component-level characterization of individual nanowires. In this paper, we present a unique experimental set-up to characterize the mechanical and electromechanical behaviour of individual nanowires. Using this set-up and complementary atomistic simulations, mechanical properties of ZnO nanowires and electromechanical properties of GaN nanowires were investigated. In ZnO nanowires, elastic modulus was found to depend on nanowire diameter decreasing from 190 GPa to 140 GPa as the wire diameter increased from 5 nm to 80 nm. Inconsistent failure mechanisms were observed in ZnO nanowires. Experiments revealed a brittle fracture, whereas simulations using a pairwise potential predicted a phase transformation prior to failure. This inconsistency is addressed in detail from an experimental as well as computational perspective. Lastly, in addition to mechanical properties, preliminary results on the electromechanical properties of gallium nitride nanowires are also reported. Initial investigations reveal that the piezoresistive and piezoelectric behaviour of nanowires is different from bulk gallium nitride.

  6. A statistical model of a metallic inclusion in semiconducting media

    Science.gov (United States)

    Shikin, V. B.

    2016-11-01

    The properties of an isolated multicharged atom embedded into a semiconducting medium are discussed. The analysis generalizes the results of the known Thomas-Fermi theory for a multicharged ( Z ≫ 1) atom in vacuum when it is immersed into an electron-hole gas of finite temperature. The Thomas-Fermi-Debye (TFD) atom problem is directly related to the properties of donors in low-doped semiconductors and is alternative in its conclusions to the ideal scenario of dissociation of donors. In the existing ideal statistics, an individual donor under infinitely low doping is completely ionized (a charged center does not hold its neutralizing counter-ions). A Thomas-Fermi-Debye atom (briefly, a TFD donor) remains a neutral formation that holds its screening "coat" even for infinitely low doping level, i.e., in the region of n d λ0 3 ≪ 1, where n d is the concentration of the doping impurity and λ0 is the Debye length with the parameters of intrinsic semiconductor. Various observed consequences in the behavior of a TFD donor are discussed that allow one to judge the reality of the implications of the TFD donor model.

  7. High temperature photoelectron emission and surface photovoltage in semiconducting diamond

    Science.gov (United States)

    Williams, G. T.; Cooil, S. P.; Roberts, O. R.; Evans, S.; Langstaff, D. P.; Evans, D. A.

    2014-08-01

    A non-equilibrium photovoltage is generated in semiconducting diamond at above-ambient temperatures during x-ray and UV illumination that is sensitive to surface conductivity. The H-termination of a moderately doped p-type diamond (111) surface sustains a surface photovoltage up to 700 K, while the clean (2 × 1) reconstructed surface is not as severely affected. The flat-band C 1s binding energy is determined from 300 K measurement to be 283.87 eV. The true value for the H-terminated surface, determined from high temperature measurement, is (285.2 ± 0.1) eV, corresponding to a valence band maximum lying 1.6 eV below the Fermi level. This is similar to that of the reconstructed (2 × 1) surface, although this surface shows a wider spread of binding energy between 285.2 and 285.4 eV. Photovoltage quantification and correction are enabled by real-time photoelectron spectroscopy applied during annealing cycles between 300 K and 1200 K. A model is presented that accounts for the measured surface photovoltage in terms of a temperature-dependent resistance. A large, high-temperature photovoltage that is sensitive to surface conductivity and photon flux suggests a new way to use moderately B-doped diamond in voltage-based sensing devices.

  8. Damage Diagnosis in Semiconductive Materials Using Electrical Impedance Measurements

    Science.gov (United States)

    Ross, Richard W.; Hinton, Yolanda L.

    2008-01-01

    Recent aerospace industry trends have resulted in an increased demand for real-time, effective techniques for in-flight structural health monitoring. A promising technique for damage diagnosis uses electrical impedance measurements of semiconductive materials. By applying a small electrical current into a material specimen and measuring the corresponding voltages at various locations on the specimen, changes in the electrical characteristics due to the presence of damage can be assessed. An artificial neural network uses these changes in electrical properties to provide an inverse solution that estimates the location and magnitude of the damage. The advantage of the electrical impedance method over other damage diagnosis techniques is that it uses the material as the sensor. Simple voltage measurements can be used instead of discrete sensors, resulting in a reduction in weight and system complexity. This research effort extends previous work by employing finite element method models to improve accuracy of complex models with anisotropic conductivities and by enhancing the computational efficiency of the inverse techniques. The paper demonstrates a proof of concept of a damage diagnosis approach using electrical impedance methods and a neural network as an effective tool for in-flight diagnosis of structural damage to aircraft components.

  9. Diameter dependence of thermoelectric power of semiconducting carbon nanotubes

    Science.gov (United States)

    Hung, Nguyen T.; Nugraha, Ahmad R. T.; Hasdeo, Eddwi H.; Dresselhaus, Mildred S.; Saito, Riichiro

    2015-10-01

    We calculate the thermoelectric power (or thermopower) of many semiconducting single wall carbon nanotubes (s-SWNTs) within a diameter range 0.5 -1.5 nm by using the Boltzmann transport formalism combined with an extended tight-binding model. We find that the thermopower of s-SWNTs increases as the tube diameter decreases. For some s-SWNTs with diameters less than 0.6 nm , the thermopower can reach a value larger than 2000 μ V /K at room temperature, which is about 6 to 10 times larger than that found in commonly used thermoelectric materials. The large thermopower values may be attributed to the one dimensionality of the nanotubes and to the presence of large band gaps of the small-diameter s-SWNTs. We derive an analytical formula to reproduce the numerical calculation of the thermopower and we find that the thermopower of a given s-SWNT is directly related with its band gap. The formula also explains the shape of the thermopower as a function of tube diameter, which looks similar to the shape of the so-called Kataura plot of the band gap dependence on tube diameter.

  10. Gas Sensors Based on Semiconducting Nanowire Field-Effect Transistors

    Directory of Open Access Journals (Sweden)

    Ping Feng

    2014-09-01

    Full Text Available One-dimensional semiconductor nanostructures are unique sensing materials for the fabrication of gas sensors. In this article, gas sensors based on semiconducting nanowire field-effect transistors (FETs are comprehensively reviewed. Individual nanowires or nanowire network films are usually used as the active detecting channels. In these sensors, a third electrode, which serves as the gate, is used to tune the carrier concentration of the nanowires to realize better sensing performance, including sensitivity, selectivity and response time, etc. The FET parameters can be modulated by the presence of the target gases and their change relate closely to the type and concentration of the gas molecules. In addition, extra controls such as metal decoration, local heating and light irradiation can be combined with the gate electrode to tune the nanowire channel and realize more effective gas sensing. With the help of micro-fabrication techniques, these sensors can be integrated into smart systems. Finally, some challenges for the future investigation and application of nanowire field-effect gas sensors are discussed.

  11. Advanced Branching Control and Characterization of Inorganic Semiconducting Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Steven Michael [Univ. of California, Berkeley, CA (United States)

    2007-01-01

    The ability to finely tune the size and shape of inorganic semiconducting nanocrystals is an area of great interest, as the more control one has, the more applications will be possible for their use. The first two basic shapes develped in nanocrystals were the sphere and the anistropic nanorod. the II_VI materials being used such as Cadmium Selenide (CdSe) and Cadmium Telluride (CdTe), exhibit polytypism, which allows them to form in either the hexagonally packed wurtzite or cubically packed zinc blende crystalline phase. The nanorods are wurtzite with the length of the rod growing along the c-axis. As this grows, stacking faults may form, which are layers of zinc blende in the otherwise wurtzite crystal. Using this polytypism, though, the first generation of branched crystals were developed in the form of the CdTe tetrapod. This is a nanocrystal that nucleates in the zincblend form, creating a tetrahedral core, on which four wurtzite arms are grown. This structure opened up the possibility of even more complex shapes and applications. This disseration investigates the advancement of branching control and further understanding the materials polytypism in the form of the stacking faults in nanorods.

  12. Magnetic endohedral transition-metal-doped semiconducting-nanoclusters.

    Science.gov (United States)

    Matxain, Jon M; Formoso, Elena; Mercero, Jose M; Piris, Mario; Lopez, Xabier; Ugalde, Jesus M

    2008-01-01

    Endohedral first-row transition-metal-doped TM@Zn(i)S(i) nanoclusters, in which TM stands for the first-row transition-metals from Sc to Zn, and i=12, 16, have been characterized. In these structures the dopant metals are trapped inside spheroidal hollow semiconducting nanoclusters. It is observed that some of the transition metals are trapped in the center of mass of the cluster, whereas others are found to be displaced from that center, leading to structures in which the transition metals display a complex dynamical behavior upon encapsulation. This fact was confirmed by quantum molecular dynamics calculations, which further confirmed the thermal stability of endohedral compounds. In the endohedrally-doped nanoclusters in which the transition-metal atom sits on the center of mass, the host hollow cluster structure remains undistorted after dopant encapsulation. Conversely, if the encapsulated transition-metal atom is displaced from the center of mass, the host hollow cluster structure suffers a very tiny distortion. Additionally, it is found that there is negligible charge transfer between the dopant transition-metal atom and its hollow cluster host and, after encapsulation, the spin densities remain localized on the transition-metal atom. This allows for the atomic-like behavior of the trapped transition-metal atom, which gives rise to their atomic-like magnetic properties. The encapsulation free energies are negative, suggesting that these compounds are thermodynamically stable.

  13. Important innovations in conventional drivage technology by a new generation of drilling jumbos; Massgebende Innovationen in der konventionellen Vortriebstechnologie durch eine neue Bohrwagengeneration

    Energy Technology Data Exchange (ETDEWEB)

    Wennmohs, Karl-Heinz [Atlas Copco MCT GmbH, Essen (Germany). Global Strategic Customers

    2009-01-29

    Important innovations in the development of the new generation of drilling jumbos led to an increase in the performance of conventional drivage technology, which had previously not been considered possible. An important factor in addition to the high drilling rate is the greater precision of the kinematics. This permits important cost savings on concrete and re-profiling. At the same time customer requirements such as the pre-drilling technology, recording of drilling parameters, profile monitoring and communication engineering were implemented in this new generation of drilling jumbos. (orig.)

  14. The Features and Effects of China's Importing Environmental Technology%中国引进环境技术的特征及效应

    Institute of Scientific and Technical Information of China (English)

    康明已; 佘群枝

    2012-01-01

    Environmental technology introduction is an important way of improving environment by getting advanced environmental technology in China.The ways of China's importing environmental technology are diversified,including the import of environmental products and services,the technological introduction brought by foreign investment,the environmental project supported by international financial organization and the environmental technology import accompanied by Clean Development Mechanism.The import of environmental technology in China focuses relatively on the new energy and renewable energy technology and it has brought further overflow effects,improved the environmental technology level in China and slowed down the emission of China's main pollutants.%环境技术引进是中国获取先进环境技术改善环境的重要途径,中国引进环境技术的渠道多元化,包括环境产品与服务的进口、外国直接投资带动的技术引进、国际金融机构援助的环境工程以及伴随清洁发展机制的环境技术引进;中国环境技术引进相对集中于新能源和可再生能源技术。环境技术的引进进一步产生技术外溢效应,提高了中国环境技术水平,减缓了中国主要污染物排放增速。

  15. Exciton Dynamics and Many Body Interactions in Layered Semiconducting Materials Revealed with Non-linear Coherent Spectroscopy

    Science.gov (United States)

    Dey, Prasenjit

    understanding the basic unexplored science as well as creating technological developments. The dephasing dynamics in semiconductors typically occur in the picosecond to femtosecond timescale, thus the use of ultrafast laser spectroscopy is a potential route to probe such excitonic responses. The focus of this dissertation is two-fold: firstly, to develop the necessary instrumentation to accurately probe the aforementioned parameters and secondly, to explore the quantum dynamics and the underlying many-body interactions in different layered semiconducting materials. A custom-built multidimensional optical non-linear spectrometer was developed in order to perform two-dimensional spectroscopic (2DFT) measurements. The advantages of this technique are multifaceted compared to regular one-dimensional and non-linear incoherent techniques. 2DFT technique is based on an enhanced version of Four wave mixing experiments. This powerful tool is capable of identifying the resonant coupling, probing the coherent pathways, unambiguously extracting the homogeneous linewidth in the presence of inhomogeneity and decomposing a complex spectra into real and imaginary parts. It is not possible to uncover such crucial features by employing one dimensional non-linear technique. Monolayers as well as bulk TMDs and group III-VI bulk layered materials are explored in this dissertation. The exciton quantum dynamics is explored with three pulse four-wave mixing whereas the phase sensitive measurements are obtained by employing two-dimensional Fourier transform spectroscopy. Temperature and excitation density dependent 2DFT experiments unfold the information associated with the many-body interactions in the layered semiconducting samples.

  16. Optics and Optoelectronics of Two-dimensional Semiconducting Monolayers and Heterostructures

    Science.gov (United States)

    Ross, Jason Solomon

    , the first valleytronic demonstration via electrical control of the degree of valley polarization, and resonant excitation investigations of the interlayer exciton's role in absorption and emission in heterostructures. This work paves the way for future studies of 2D semiconducting systems and utilizing them in important new devices ranging from LEDs to photovoltaics to photonically coupled nanosystems such as a 2D nanolaser.

  17. A Comparison of Photocurrent Mechanisms in Quasi-Metallic and Semiconducting Carbon Nanotube pn-Junctions.

    Science.gov (United States)

    Chang, Shun-Wen; Hazra, Jubin; Amer, Moh; Kapadia, Rehan; Cronin, Stephen B

    2015-12-22

    We present a comparative study of quasi-metallic (Eg ∼ 100 meV) and semiconducting (Eg ∼ 1 eV) suspended carbon nanotube pn-junctions introduced by electrostatic gating. While the built-in fields of the quasi-metallic carbon nanotubes (CNTs) are 1-2 orders of magnitude smaller than those of the semiconducting CNTs, their photocurrent is 2 orders of magnitude higher than the corresponding semiconducting CNT devices under the same experimental conditions. Here, the large exciton binding energy in semiconducting nanotubes (∼400 meV) makes it difficult for excitons to dissociate into free carriers that can contribute to an externally measured photocurent. As such, semiconducting nanotubes require a phonon to assist in the exciton dissociation process, in order to produce a finite photocurrent, while quasi-metallic nanotubes do not. The quasi-metallic nanotubes have much lower exciton binding energies (∼50 meV) as well as a continuum of electronic states to decay into and, therefore, do not require the absorption of a phonon in order to dissociate, making it much easier for these excitons to produce a photocurrent. We performed detailed simulations of the band energies in quasi-metallic and semiconducting nanotube devices in order to obtain the electric field profiles along the lengths of the nanotubes. These simulations predict maximum built-in electric field strengths of 2.3 V/μm for semiconducting and 0.032-0.22 V/μm for quasi-metallic nanotubes under the applied gate voltages used in this study.

  18. Flow induced/ refined solution crystallization of a semiconducting polymer

    Science.gov (United States)

    Nguyen, Ngoc A.

    Organic photovoltaics, a new generation of solar cells, has gained scientific and economic interests due to the ability of solution-processing and potentially low-cost power production. Though, the low power conversion efficiency of organic/ plastic solar cells is one of the most pertinent challenges that has appealed to research communities from many different fields including materials science and engineering, electrical engineering, chemical engineering, physics and chemistry. This thesis focuses on investigating and controlling the morphology of a semi-conducting, semi-crystalline polymer formed under shear-flow. Molecular structures and processing techniques are critical factors that significantly affect the morphology formation in the plastic solar cells, thus influencing device performance. In this study, flow-induced solution crystallization of poly (3-hexylthiophene) (P3HT) in a poor solvent, 2-ethylnapthalene (2-EN) was utilized to make a paint-like, structural liquid. The polymer crystals observed in this structured paint are micrometers long, nanometers in cross section and have a structure similar to that formed under quiescent conditions. There is pi-pi stacking order along the fibril axis, while polymer chain folding occurs along the fibril width and the order of the side-chain stacking is along fibril height. It was revealed that shear-flow not only induces P3HT crystallization from solution, but also refines and perfects the P3HT crystals. Thus, a general strategy to refine the semiconducting polymer crystals from solution under shear-flow has been developed and employed by simply tuning the processing (shearing) conditions with respect to the dissolution temperature of P3HT in 2-EN. The experimental results demonstrated that shear removes defects and allows more perfect crystals to be formed. There is no glass transition temperature observed in the crystals formed using the flow-induced crystallization indicating a significantly different

  19. Intrinsically stretchable and healable semiconducting polymer for organic transistors

    Science.gov (United States)

    Oh, Jin Young; Rondeau-Gagné, Simon; Chiu, Yu-Cheng; Chortos, Alex; Lissel, Franziska; Wang, Ging-Ji Nathan; Schroeder, Bob C.; Kurosawa, Tadanori; Lopez, Jeffrey; Katsumata, Toru; Xu, Jie; Zhu, Chenxin; Gu, Xiaodan; Bae, Won-Gyu; Kim, Yeongin; Jin, Lihua; Chung, Jong Won; Tok, Jeffrey B.-H.; Bao, Zhenan

    2016-11-01

    Thin-film field-effect transistors are essential elements of stretchable electronic devices for wearable electronics. All of the materials and components of such transistors need to be stretchable and mechanically robust. Although there has been recent progress towards stretchable conductors, the realization of stretchable semiconductors has focused mainly on strain-accommodating engineering of materials, or blending of nanofibres or nanowires into elastomers. An alternative approach relies on using semiconductors that are intrinsically stretchable, so that they can be fabricated using standard processing methods. Molecular stretchability can be enhanced when conjugated polymers, containing modified side-chains and segmented backbones, are infused with more flexible molecular building blocks. Here we present a design concept for stretchable semiconducting polymers, which involves introducing chemical moieties to promote dynamic non-covalent crosslinking of the conjugated polymers. These non-covalent crosslinking moieties are able to undergo an energy dissipation mechanism through breakage of bonds when strain is applied, while retaining high charge transport abilities. As a result, our polymer is able to recover its high field-effect mobility performance (more than 1 square centimetre per volt per second) even after a hundred cycles at 100 per cent applied strain. Organic thin-film field-effect transistors fabricated from these materials exhibited mobility as high as 1.3 square centimetres per volt per second and a high on/off current ratio exceeding a million. The field-effect mobility remained as high as 1.12 square centimetres per volt per second at 100 per cent strain along the direction perpendicular to the strain. The field-effect mobility of damaged devices can be almost fully recovered after a solvent and thermal healing treatment. Finally, we successfully fabricated a skin-inspired stretchable organic transistor operating under deformations that might be

  20. Intrinsically stretchable and healable semiconducting polymer for organic transistors.

    Science.gov (United States)

    Oh, Jin Young; Rondeau-Gagné, Simon; Chiu, Yu-Cheng; Chortos, Alex; Lissel, Franziska; Wang, Ging-Ji Nathan; Schroeder, Bob C; Kurosawa, Tadanori; Lopez, Jeffrey; Katsumata, Toru; Xu, Jie; Zhu, Chenxin; Gu, Xiaodan; Bae, Won-Gyu; Kim, Yeongin; Jin, Lihua; Chung, Jong Won; Tok, Jeffrey B-H; Bao, Zhenan

    2016-11-17

    Thin-film field-effect transistors are essential elements of stretchable electronic devices for wearable electronics. All of the materials and components of such transistors need to be stretchable and mechanically robust. Although there has been recent progress towards stretchable conductors, the realization of stretchable semiconductors has focused mainly on strain-accommodating engineering of materials, or blending of nanofibres or nanowires into elastomers. An alternative approach relies on using semiconductors that are intrinsically stretchable, so that they can be fabricated using standard processing methods. Molecular stretchability can be enhanced when conjugated polymers, containing modified side-chains and segmented backbones, are infused with more flexible molecular building blocks. Here we present a design concept for stretchable semiconducting polymers, which involves introducing chemical moieties to promote dynamic non-covalent crosslinking of the conjugated polymers. These non-covalent crosslinking moieties are able to undergo an energy dissipation mechanism through breakage of bonds when strain is applied, while retaining high charge transport abilities. As a result, our polymer is able to recover its high field-effect mobility performance (more than 1 square centimetre per volt per second) even after a hundred cycles at 100 per cent applied strain. Organic thin-film field-effect transistors fabricated from these materials exhibited mobility as high as 1.3 square centimetres per volt per second and a high on/off current ratio exceeding a million. The field-effect mobility remained as high as 1.12 square centimetres per volt per second at 100 per cent strain along the direction perpendicular to the strain. The field-effect mobility of damaged devices can be almost fully recovered after a solvent and thermal healing treatment. Finally, we successfully fabricated a skin-inspired stretchable organic transistor operating under deformations that might be

  1. Large Area Fabrication of Semiconducting Phosphorene by Langmuir-Blodgett Assembly

    Science.gov (United States)

    Kaur, Harneet; Yadav, Sandeep; Srivastava, Avanish. K.; Singh, Nidhi; Schneider, Jörg J.; Sinha, Om. P.; Agrawal, Ved V.; Srivastava, Ritu

    2016-01-01

    Phosphorene is a recently new member of the family of two dimensional (2D) inorganic materials. Besides its synthesis it is of utmost importance to deposit this material as thin film in a way that represents a general applicability for 2D materials. Although a considerable number of solvent based methodologies have been developed for exfoliating black phosphorus, so far there are no reports on controlled organization of these exfoliated nanosheets on substrates. Here, for the first time to the best of our knowledge, a mixture of N-methyl-2-pyrrolidone and deoxygenated water is employed as a subphase in Langmuir-Blodgett trough for assembling the nanosheets followed by their deposition on substrates and studied its field-effect transistor characteristics. Electron microscopy reveals the presence of densely aligned, crystalline, ultra-thin sheets of pristine phosphorene having lateral dimensions larger than hundred of microns. Furthermore, these assembled nanosheets retain their electronic properties and show a high current modulation of 104 at room temperature in field-effect transistor devices. The proposed technique provides semiconducting phosphorene thin films that are amenable for large area applications. PMID:27671093

  2. Strain compensation in a semiconducting device structure using an intentionally mismatched uniform buffer layer

    Science.gov (United States)

    Kujofsa, Tedi; Ayers, John E.

    2016-12-01

    The extent of strain relaxation in semiconducting device heterostructures has important implications in the design of high electron mobility transistors, light-emitting diodes, and laser diodes, in which the residual strain affects the device characteristics. In this work, we develop the theoretical framework for understanding strain compensation in a semiconductor device layer using a uniform buffer layer which can be intentionally mismatched to the material above. Specifically, we determined the critical condition for complete strain compensation in the device layer by intentionally introducing a compositional mismatch at the device-buffer interface. We present minimum energy calculations and show that for a given device layer with fixed mismatch and layer thickness, the buffer layer may be designed with the appropriate combination of thickness and mismatch such that the device layer will have zero residual strain in equilibrium. Such a structure can be referred to as a completely strain-compensated design. In the more general case, there may be partial strain compensation, and we give a simple physics-based Gaussian-type function describing the residual strain in the device layer. We have applied this general framework to In x Ga1-x As/GaAs (001) heterostructures for the purpose of illustration, but the work is applicable to any diamond or zinc blende (001) heteroepitaxial material system.

  3. Surfactant free fractions of metallic and semiconducting single-walled carbon nanotubes via optimised gel chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lukaszczuk, Pawel, E-mail: plukaszczuk@zut.edu.pl [West Pomeranian University of Technology, Institute of Chemical and Environment Engineering, ul. Pulaskiego 10, 70-322 Szczecin (Poland); Ruemmeli, Mark H.; Knupfer, Martin [Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstr. 20, 01069 Dresden (Germany); Kalenczuk, Ryszard J.; Borowiak-Palen, Ewa [West Pomeranian University of Technology, Institute of Chemical and Environment Engineering, ul. Pulaskiego 10, 70-322 Szczecin (Poland)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer The application of gel permeation chromatography technique in a field of SWCNT separation. Black-Right-Pointing-Pointer Non-commercial agarose gel used as a column filling. Black-Right-Pointing-Pointer Purification route is presented, quality and quantity estimation is shown. Black-Right-Pointing-Pointer Process is ready for high-scale separation of SWCNTs. -- Abstract: We report the procedure of sorting/purification of carbon nanotubes by electronic type using chromatographic column with sodium dodecylsulfate (SDS) and sodium deoxycholate (DOC) solutions as the eluents. The non-commercial agarose gel in different concentrations has been tested in the process. It was found that in optimal gel concentration the fractionation resulted in {approx}96.2% yield of semiconducting species. Importantly, to get surfactant-free fractions the post-separation purification procedure has been carried out. The UV-vis-NIR and Raman spectroscopy have been utilised for the samples analysis. High resolution transmission microscopy and thermogravimetric analysis allowed to study the sample morphology and purity, respectively.

  4. Charge-carrier mobilities in disordered semiconducting polymers: effects of carrier density and electric field

    Energy Technology Data Exchange (ETDEWEB)

    Meisel, K.D.; Pasveer, W.F.; Cottaar, J.; Bobbert, P.A.; Michels, M.A.J. [Group Polymer Physics, Eindhoven Polymer Laboratories and Dutch Polymer Institute, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Tanase, C.; Blom, P.W.M. [Materials Science Centre and Dutch Polymer Institute, Nijenborgh 4, 9747 AG Groningen (Netherlands); Coehoorn, R.; Leeuw, D.M. de [Philips Research Laboratories, Prof. Holstlaan 4, 5656 AA Eindhoven (Netherlands)

    2006-02-01

    We model charge transport in disordered semiconducting polymers by hopping of charge carriers on a square lattice of sites with Gaussian on-site energy disorder, using Fermi-Dirac statistics. From numerically exact solutions of the Master equation, we study the dependence of the charge-carrier mobility on temperature, carrier density, and electric field. Our results are used in calculating current-voltage characteristics of hole-only polymer diodes. It is found that very good fits to experimental current-voltage characteristics can be obtained at different temperatures, with reasonable fitting parameters for the width of the Gaussian density of states and the lattice constant. In agreement with the experiments we find that the density dependence is dominant over the field dependence. Only at high fields and low temperatures the field dependence becomes noticeable. The potential and current distribution show strong inhomogeneities, which may have important consequences for the operation of polymer opto-electronic devices. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Determining the most important factors for sustainable energy technology selection in Africa: application of the Delphi technique

    CSIR Research Space (South Africa)

    Barry, M-L

    2008-04-01

    Full Text Available into account when identifying the most sustainable technological systems in the African context. The study utilised the Delphi technique. The questionnaire of the first round was based on factors identified during a focus group exercise with energy experts...

  6. High Technology Development and Creation of Experimental Industrial Area of High-Performance Precision Diamond Dress Tool Production for Engineering Needs and Import Substitution in Ukraine

    Directory of Open Access Journals (Sweden)

    N. Novikov

    2013-09-01

    Full Text Available Manufacturing design of high-precision diamond tool for special applications carried out at V. M Bakul Institute for Superhard Materials of NAS of Ukraine is described. Presented developments open up scientific and technological capabilities of special dress diamond tool production for mechanical engineering and substitution of imported tools at Ukrainian enterprises by home-produced.

  7. Transport studies of conducting, semiconducting and photoconducting star polymers

    Science.gov (United States)

    Ferguson, John Baker

    Star polymers are studied for their transport properties in the highly conducting state doped with NOPF6 and iodine, the undoped semiconducting state and the photoconducting state. Doped star polymers exhibit variable range hopping of charge carriers. Transport dimensionality and conductivity depend intricately on the processing conditions for doping and casting films. The highest conducting diffusion doped film (room temperature conductivity 50 S/cm) exhibits 2-dimensional variable range for all doping levels. Polymers doped in solution, then cast to form films have 1.4 dimensional variable range hopping for the highest conducting samples with 10 S/cm at room temperature. The hopping dimensionality varies as the conductivity decreases. The doped star polymers remain on the insulator side of the insulator metal transition with localized carriers as revealed with Kramer-Kronig analysis. Optical and near infrared absorbance and photoluminescence reveal the core of the star polymers exist in a solid state solution of the arms with similar absorbance and luminescence for both solution and films. The arms retain the optical properties of their linear analogs indicating the core and arms do not interact quantum mechanically to produce a new state. Excitons created by absorption in the wider band gap cores rapidly migrate to the arms. Photoconductive time of flight mobility measurements reveal an almost field independent mobility at room temperature. This is due to a unique cancellation of on diagonal and off diagonal disorder in the Bassler disorder formalism. The cores introduce heterogeneous regions with a net lower mobility predicted by correlated disorder models. Space charge limited current reveals trap densities several orders of magnitude higher than the carrier density. Photovoltaic performance of star polymer and fullerene blend devices with both 20 nm and 100 nm thick layers are investigated. The thin devices have low open circuit voltages due to space charge

  8. Oxidation behavior of Cu nanoparticles embedded into semiconductive TiO{sub 2} matrix

    Energy Technology Data Exchange (ETDEWEB)

    Stranak, Vitezslav, E-mail: stranak@prf.jcu.cz [University of South Bohemia, Faculty of Science, Branisovska 31, 37005 Ceske Budejovice (Czech Republic); Drache, Steffen; Wulff, Harm [University of Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Hubicka, Zdenek [Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, 18221 Prague (Czech Republic); Tichy, Milan [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, 18000 Prague (Czech Republic); Kruth, Angela [Leibniz Institute for Plasma Science and Technology, INP Greifswald e.V., Felix-Hausdorff-Straße 2, 17489 Greifswald (Germany); Helm, Christiane A.; Hippler, Rainer [University of Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany)

    2015-08-31

    Metal nanoparticles embedded into a semiconductive matrix represent a promising material for widely sought advanced technological applications. We focused our interest on the preparation of TiO{sub 2} matrix with embedded Cu nanoparticles. In particular, we studied the effect of reactive discharge (Ar/O{sub 2}) exposition on copper oxidation, which can result in two stable forms: cuprous oxide (Cu{sub 2}O) and cupric oxide (CuO). Copper nanoparticles, of size in range 10–50 nm, were produced by magnetron sputtering in combination with gas aggregation. The beam of Cu nanoparticles was impinging onto a silicon substrate which was directly exposed to a reactive Ar/O{sub 2} magnetron discharge providing sputtering of Ti target at the same time. The properties of deposited nanocomposite Cu({sub x}O)–TiO{sub 2} were investigated by X-ray photoelectron spectroscopy, grazing incidence X-ray diffractometry, X-ray reflectometry and scanning electron microscopy techniques to reveal the nanocomposite properties and to understand the oxidation process of embedded Cu nanoparticles. It was found that CuO is preferentially formed if copper is exposed to active oxygen species (O{sup +}, O{sup −}, O{sup ⁎} etc.) produced in the reactive magnetron discharge. On the other hand, Cu{sub 2}O was observed in the case of copper reaction in ambient Ar/O{sub 2} atmosphere. As a result, two possible copper oxidation mechanisms are proposed, employing chemical kinetics. - Highlights: • Cu–TiO{sub 2} nanocomposite was prepared by plasma assisted methods. • Embedded Cu always occurs in oxidized phase depending on the way of oxidation. • CuO is formed if copper is exposed to active oxygen species produced in Ar/O{sub 2} discharge. • Cu{sub 2}O appears in the case of copper reaction in an ambient oxygen-based atmosphere. • Two possible copper oxidation mechanisms are proposed.

  9. PREFACE: 18th Microscopy of Semiconducting Materials Conference (MSM XVIII)

    Science.gov (United States)

    Walther, T.; Hutchison, John L.

    2013-11-01

    YRM logo This volume contains invited and contributed papers from the 18th international conference on 'Microscopy of Semiconducting Materials' held at St Catherine's College, University of Oxford, on 7-11 April 2013. The meeting was organised under the auspices of the Royal Microscopical Society and supported by the Institute of Physics as well as the Materials Research Society of the USA. This conference series deals with recent advances in semiconductor studies carried out by all forms of microscopy, with an emphasis on electron microscopy and scanning probe microscopy with high spatial resolution. This time the meeting was attended by 109 delegates from 17 countries world-wide. We were welcomed by Professor Sir Peter Hirsch, who noted that this was the first of these conferences where Professor Tony Cullis was unable to attend, owing to ill-health. During the meeting a card containing greetings from many of Tony's friends and colleagues was signed, and duly sent to Tony afterwards. As semiconductor devices shrink further new routes for device processing and characterisation need to be developed, and, for the latter, methods that offer sub-nanometre spatial resolution are particularly valuable. The various forms of imaging, diffraction and spectroscopy available in modern microscopes are powerful tools for studying the microstructure, electronic structure, chemistry and also electric fields in semiconducting materials. Recent advances in instrumentation, from lens aberration correction in both TEM and STEM instruments, to the development of a wide range of scanning probe techniques, as well as new methods of signal quantification have been presented at this conference. Two topics that have at this meeting again highlighted the interesting contributions of aberration corrected transmission electron microscopy were: contrast quantification of annular dark-field STEM images in terms of chemical composition (Z-contrast), sample thickness and strain, and the study of

  10. Semiconducting graphene nanoribbon retains band gap on amorphous or crystalline SiO_2

    OpenAIRE

    Hossain, M. Zubaer

    2011-01-01

    Electronic properties of a semiconducting armchair graphene nanoribbon on SiO_2 are examined using first-principles calculations and taking into account the van der Waals interaction. Unlike semiconducting carbon nanotubes, which exhibit variations in band gap on SiO_2, the nanoribbon is found to retain its band gap on SiO_2, regardless of the separation distance or the dielectric’s surface type—crystalline or amorphous. The interfacial interaction leads to electron-transfer from the nanor...

  11. Self-assembled lamellar MoS2, SnS2 and SiO2 semiconducting polymer nanocomposites.

    Science.gov (United States)

    Kirmayer, Saar; Aharon, Eyal; Dovgolevsky, Ekaterina; Kalina, Michael; Frey, Gitti L

    2007-06-15

    Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS(2) and SnS(2) are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS(2) show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS(2) hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS(2), demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.

  12. The importance of showing technological tools (like Cmap Tools to future teachers to improve their teaching practice in school

    Directory of Open Access Journals (Sweden)

    Emilio CRISOL MOYA

    2012-12-01

    Full Text Available Concept maps have proved to be an efficient tool for learning (Novak & Gowin, 1984 but also without the pretext of making a classification, one could say that has also been found useful to: identify students’ prior knowledge, summarizing what has been learned, note taking, help in the study, plan, build scaffolding for understanding, strengthen educational experiences, improve conditions for effective learning, promote critical thinking, support cooperation and collaboration, organize content (Cañas & Badilla, 2005; Coffey et al., 2003. In this study, we show the opinions concerning the use of Cmap Tools as a tool for making concept maps for their future practice as teachers in primary education, students of second year of teaching at the University of Granada. The research was based on the quantitative perspective, being the instrument used, a questionnaire released by one hand, the students’ opinion on the use of the methodology used: group activity and selfemployment, and the application of the tool Cmap Tools, and collect other personal and academic satisfaction of students involved in this experience. As for the extracted views emphasized that although student teachers feel that using technology in their classes, can be a strategy that promotes the teaching and learning, as claimed on this experience, it is true that students who do not coexist think so, hence it is necessary to strengthen this small percentage use of technological tools in teaching.

  13. Spin transport in lateral structures with semiconducting channel

    Science.gov (United States)

    Zainuddin, Abu Naser

    Spintronics is an emerging field of electronics with the potential to be used in future integrated circuits. Spintronic devices are already making their mark in storage technologies in recent times and there are proposals for using spintronic effects in logic technologies as well. So far, major improvement in spintronic effects, for example, the `spin-valve' effect, is being achieved in metals or insulators as channel materials. But not much progress is made in semiconductors owing to the difficulty in injecting spins into them, which has only very recently been overcome with the combined efforts of many research groups around the world. The key motivations for semiconductor spintronics are their ease in integration with the existing semiconductor technology along with the gate controllability. At present semiconductor based spintronic devices are mostly lateral and are showing a very poor performance compared to their metal or insulator based vertical counterparts. The objective of this thesis is to analyze these devices based on spin-transport models and simulations. At first a lateral spin-valve device is modeled with the spin-diffusion equation based semiclassical approach. Identifying the important issues regarding the device performance, a compact circuit equivalent model is presented which would help to improve the device design. It is found that the regions outside the current path also have a significant influence on the device performance under certain conditions, which is ordinarily neglected when only charge transport is considered. Next, a modified spin-valve structure is studied where the spin signal is controlled with a gate in between the injecting and detecting contacts. The gate is used to modulate the rashba spin-orbit coupling of the channel which, in turn, modulates the spin-valve signal. The idea of gate controlled spin manipulation was originally proposed by Datta and Das back in 1990 and is called 'Datta-Das' effect. In this thesis, we have

  14. ROLE AND IMPORTANCE OF TECHNOLOGY DEVELOPMENT AND IMPROVEMENT EMERGENCY ASSISTANCE AND SUSTAINABLE DEVELOPMENT AND ENVIRONMENTAL PROTECTION IN ROMANIA

    Directory of Open Access Journals (Sweden)

    Ionel NUTA

    2015-08-01

    Full Text Available Year 2014 was considered by NASA and NOAA hottest year in history. Combined temperature of the atmosphere and oceans has increased overall by 0.68 degrees Celsius, and the devastating effects of climate changes produced irreversible consequences on the sustainability of the planet earth. Increasing the frequency, intensity and complexity of their manifestation caused initiation and development of global policies aimed at mitigating climate change priority, reducing the risk of natural disasters or anthropological costs and negative effects to society and the environment. In order to fulfill the responsibilities assumed by Romania as a member of international bodies is necessary to search and apply new solutions as revolutionary and effective, especially autonomous enabling technology development and improvement of emergency intervention and replacement of emergency autonomous robotic systems. Autonomous robotic systems allow execution of prevention and management of emergencies in areas difficult to reach, hostile life and result in increasing their efficiency.

  15. Biogas technology - an important link in environmentally sound management of wastes. Biogasteknik - en viktig laenk i en miljoevaenlig avfallshantering

    Energy Technology Data Exchange (ETDEWEB)

    Szikriszt, G. (Biomet AB, Sundbyberg (SE)); Frostell, B. (IVL, Stockholm (SE))

    1989-01-01

    Biogas technology is an interesting alternative for organic waste stabilization in a future waste treatment system. This is especially the case if organic wastes are collected as concentrated and uncontaminated as possible. Proposedly, food waste should be collected separately at the household level together with toilet waste from water conserving systems. Despite this being a future vision, there is already today a considerable amount of waste available that would suit the concept. Wastes from restaurants, ships, airplanes, summer-houses, grocery shops etc. are good examples. An economic analysis showed that rather large plants would be necessary to achieve a profitable system if credit is given to the biogas only. If alternative waste handling costs and the fermentation residue are also valued however, there is a potential to construct also small profitable plants.

  16. PREFACE: 17th International Conference on Microscopy of Semiconducting Materials 2011

    Science.gov (United States)

    Walther, T.; Midgley, P. A.

    2011-11-01

    This volume contains invited and contributed papers from the 17th international conference on 'Microscopy of Semiconducting Materials' held at Churchill College, University of Cambridge, on 4-7 April 2011. The meeting was organised under the auspices of the Institute of Physics and supported by the Royal Microscopical Society as well as the Materials Research Society of the USA. This conference series deals with recent advances in semiconductor studies carried out by all forms of microscopy, with an emphasis on electron microscopy and related techniques with high spatial resolution. This time the meeting was attended by 131 delegates from 25 countries world-wide, a record in terms of internationality. As semiconductor devices shrink further new routes of device processing and characterisation need to be developed, and, for the latter, methods that offer sub-nanometre spatial resolution are particularly valuable. The various forms of imaging, diffraction and spectroscopy available in modern microscopes are powerful tools for studying the microstructure, the electronic structure, the chemistry and also electric fields in semiconducting materials. Recent advances in instrumentation, from lens aberration correction in both TEM and STEM instruments, to the development of a wide range of scanning probe techniques, as well as new methods of signal quantification have been presented at this conference. Two examples of topics at this meeting that have attracted a number of interesting studies were: the correlation of microstructural, optical and chemical information at atomic resolution with nanometre-scale resolved maps of the local electrical fields in (In,Al)GaN based semiconductors and tomographic approaches to characterise ensembles of nanowires and stacks of processed layers in devices Figure 1 Figure 1. Opening lecture by Professor Sir Colin J Humphreys. Each manuscript submitted for publication in this proceedings volume has been independently reviewed and revised

  17. Assembly, physics, and application of highly electronic-type purified semiconducting carbon nanotubes in aligned array field effect transistors and photovoltaics

    Science.gov (United States)

    Arnold, Michael

    2015-03-01

    Recent advances in (1) achieving highly monodisperse semiconducting carbon nanotubes without problematic metallic nanotubes and (2) depositing these nanotubes into useful, organized arrays and assemblies on substrates have created new opportunities for studying the physics of these one-dimensional conductors and for applying them in electronics and photonics technologies. In this talk, I will present on two topics that are along these lines. In the first, we have pioneered a scalable approach for depositing aligned arrays of ultrahigh purity semiconducting SWCNTs (prepared using polyfluorene-derivatives) called floating evaporative self-assembly (FESA). FESA is exploited to create FETs with exceptionally high combined on-conductance and on-off ratio of 261 μS/ μm and 2 x105, respectively, for a channel length of 240 nm. This is 1400 x greater on-off ratio than SWCNT FETs fabricated by other methods, at comparable on-conductance per width of 250 μS/ μm, and 30-100 x greater on-conductance per width, at comparable on-off ratio of 105-107. In the second, we have discovered how to efficiently harvest photons using semiconducting SWCNTs by driving the dissociation of excitons using donor/acceptor heterojunctions. The flow of energy in SWCNT films occurs across a complex energy landscape, temporally resolved using two-dimensional white light ultrafast spectroscopy. We have demonstrated simple solar cells driven by SWCNT excitons, based on bilayers between C60 and ultrathin (5 nm) films of SWCNTs that achieve a 1% solar power conversion efficiency (7% at the bandgap). High internal quantum efficiency indicates that future blended or multijunction cells exploiting multiple layers will be many times more efficient.

  18. Utilizing a scale model solar system project to visualize important planetary science concepts and develop technology and spatial reasoning skills

    Science.gov (United States)

    Kortenkamp, Stephen J.; Brock, Laci

    2016-10-01

    Scale model solar systems have been used for centuries to help educate young students and the public about the vastness of space and the relative sizes of objects. We have adapted the classic scale model solar system activity into a student-driven project for an undergraduate general education astronomy course at the University of Arizona. Students are challenged to construct and use their three dimensional models to demonstrate an understanding of numerous concepts in planetary science, including: 1) planetary obliquities, eccentricities, inclinations; 2) phases and eclipses; 3) planetary transits; 4) asteroid sizes, numbers, and distributions; 5) giant planet satellite and ring systems; 6) the Pluto system and Kuiper belt; 7) the extent of space travel by humans and robotic spacecraft; 8) the diversity of extrasolar planetary systems. Secondary objectives of the project allow students to develop better spatial reasoning skills and gain familiarity with technology such as Excel formulas, smart-phone photography, and audio/video editing.During our presentation we will distribute a formal description of the project and discuss our expectations of the students as well as present selected highlights from preliminary submissions.

  19. The importance of long-term social research in enabling participation and developing engagement strategies for new dengue control technologies.

    Science.gov (United States)

    McNaughton, Darlene

    2012-01-01

    In recent years, new strategies aimed at reducing the capacity of mosquito vectors to transmit dengue fever have emerged. As with earlier control methods, they will have to be employed in a diverse range of communities across the globe and into the main settings for disease transmission, the homes, businesses and public buildings of residents in dengue-affected areas. However, these strategies are notably different from previous methods and draw on technologies that are not without controversy. Public engagement and authorization are critical to the future success of these programs. This paper reports on an Australian case study where long-term social research was used to enable participation and the design of an engagement strategy tailored specifically to the sociopolitical setting of a potential trial release site of Wolbachia-infected Aedes aegytpi mosquitoes. Central themes of the social research, methods used and conclusions drawn are briefly described. Results indicate that different communities are likely to have divergent expectations, concerns and cultural sensibilities with regard to participation, engagement and authorization. The findings show that a range of issues need to be understood and taken into account to enable sensitive, ethical and effective engagement when seeking public support for new dengue control methods.

  20. The importance of long-term social research in enabling participation and developing engagement strategies for new dengue control technologies.

    Directory of Open Access Journals (Sweden)

    Darlene McNaughton

    Full Text Available BACKGROUND: In recent years, new strategies aimed at reducing the capacity of mosquito vectors to transmit dengue fever have emerged. As with earlier control methods, they will have to be employed in a diverse range of communities across the globe and into the main settings for disease transmission, the homes, businesses and public buildings of residents in dengue-affected areas. However, these strategies are notably different from previous methods and draw on technologies that are not without controversy. Public engagement and authorization are critical to the future success of these programs. METHODOLOGY/PRINCIPAL FINDINGS: This paper reports on an Australian case study where long-term social research was used to enable participation and the design of an engagement strategy tailored specifically to the sociopolitical setting of a potential trial release site of Wolbachia-infected Aedes aegytpi mosquitoes. Central themes of the social research, methods used and conclusions drawn are briefly described. Results indicate that different communities are likely to have divergent expectations, concerns and cultural sensibilities with regard to participation, engagement and authorization. CONCLUSIONS/SIGNIFICANCE: The findings show that a range of issues need to be understood and taken into account to enable sensitive, ethical and effective engagement when seeking public support for new dengue control methods.

  1. Growth and electronic structure studies of semiconducting thin films of fluorine-monosubstituted fused-thiophene derivative

    Energy Technology Data Exchange (ETDEWEB)

    Lue, Jian-Wei; Lin, Yu-Hsiang [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Yang, Yaw-Wen, E-mail: yang@nsrrc.org.tw [Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan (China); National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China)

    2014-10-15

    Highlights: • Initial growth of m-FT-BTDT films on Au(1 1 1) is governed by SK mechanism. • m-FT-BTDT growth on Au(1 1 1)-thiolate changed into a pseudo layer growth mode. • Abnormal XPS Au signal jump at ML is due to lifting of Au surface reconstruction. • Orientation difference of m-FT-BTDT in initial growth is carried over to thick films. • Marked UPS spectral change with film thickness only observable on Au(1 1 1). - Abstract: Formation of high quality interface between metal and organic semiconducting film is important in realizing high-performance organic electronics devices. We have investigated the room-temperature growth of organic semiconducting thin films of monofluorine-substituted 2-phenylbenzo[d,d′]thieno[3,2-b;4,5-b′]-dithiophene (m-FP-BTDT) on Au(1 1 1), and Au(1 1 1) modified by benzenethiolate (Au-BT) by means of synchrotron-based electron spectroscopies. XPS intensity analysis shows that on Au(1 1 1), m-FP-BTDT film grows according to Stranski–Krastanov (SK) mode in which the first monolayer (ML) is completed before the 3D growth sets in. In comparison, the initial growth of m-FP-BTDT on Au-BT proceeds via a pseudo layer-by-layer growth mechanism in which the growth of a new layer starts after the underneath layers are almost finished. Orientations of m-FP-BTDT molecules for the thick films on two substrates remain different, despite the large thickness. NEXAFS data show that m-FP-BTDT molecules on Au-BT adopt a more erected configuration, resulting in a better cofacial π-stacking. Work function for the thick m-FP-BTDT film on Au-BT is determined with UPS as 4.62 eV and the hole injection barrier as 0.95 eV.

  2. Multicomponent semiconducting polymer systems with low crystallization-induced percolation threshold

    DEFF Research Database (Denmark)

    Goffri, S.; Müller, C.; Stingelin-Stutzmann, N.;

    2006-01-01

    Blends and other multicomponent systems are used in various polymer applications to meet multiple requirements that cannot be fulfilled by a single material1, 2, 3. In polymer optoelectronic devices it is often desirable to combine the semiconducting properties of the conjugated species with the ......Blends and other multicomponent systems are used in various polymer applications to meet multiple requirements that cannot be fulfilled by a single material1, 2, 3. In polymer optoelectronic devices it is often desirable to combine the semiconducting properties of the conjugated species...... of the two components, during which the semiconductor is predominantly expelled to the surfaces of cast films, we can obtain vertically stratified structures in a one-step process. Incorporating these as active layers in polymer field-effect transistors, we find that the concentration of the semiconductor......–crystalline/semiconducting–insulating multicomponent systems offer expanded flexibility for realizing high-performance semiconducting architectures at drastically reduced materials cost with improved mechanical properties and environmental stability, without the need to design all performance requirements into the active semiconducting polymer...

  3. Semiconducting single-walled carbon nanotubes on demand by polymer wrapping

    NARCIS (Netherlands)

    Gomulya, Widianta; Costanzo, Guadalupe Diaz; Figueiredo de Carvalho, Elton; Bisri, Satria Zulkarnaen; Derenskyi, Vladimir; Fritsch, Martin; Fröhlich, Nils; Allard, Sybille; Gordiichuk, Pavlo; Herrmann, Andreas; Marrink, Siewert Jan; dos Santos, Maria Cristina; Scherf, Ulrich; Loi, Maria Antonietta

    2013-01-01

    Efficient selection of semiconducting SWCNTs of large diameter range (0.8-1.6 nm) on demand is demonstrated. Different diameters of SWCNT are systematically selected by tuning the alkyl side-chain lengths of the wrapping polymers of similar backbone. The exceptional quality and high concentration of

  4. Polaron hopping mediated by nuclear tunnelling in semiconducting polymers at high carrier density

    NARCIS (Netherlands)

    Asadi, Kamal; Kronemeijer, Auke J.; Cramer, Tobias; Koster, L. Jan Anton; Blom, Paul W. M.; de Leeuw, Dago M.

    2013-01-01

    The transition rate for a single hop of a charge carrier in a semiconducting polymer is assumed to be thermally activated. As the temperature approaches absolute zero, the predicted conductivity becomes infinitesimal in contrast to the measured finite conductivity. Here we present a uniform descript

  5. Fabrication of electrically bistable organic semiconducting/ferroelectric blend films by temperature controlled spin coating.

    Science.gov (United States)

    Hu, Jinghang; Zhang, Jianchi; Fu, Zongyuan; Weng, Junhui; Chen, Weibo; Ding, Shijin; Jiang, Yulong; Zhu, Guodong

    2015-03-25

    Organic semiconducting/ferroelectric blend films attracted much attention due to their electrical bistability and rectification properties and thereof the potential in resistive memory devices. During film deposition from the blend solution, spinodal decomposition induced phase separation, resulting in discrete semiconducting phase whose electrical property could be modulated by the continuous ferroelectric phase. However, blend films processed by common spin coating method showed extremely rough surfaces, even comparable to the film thickness, which caused large electrical leakage and thus compromised the resistive switching performance. To improve film roughness and thus increase the productivity of these resistive devices, we developed temperature controlled spin coating technique to carefully adjust the phase separation process. Here we reported our experimental results from the blend films of ferroelectric poly(vinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) and semiconducting poly(3-hexylthiophene) (P3HT). We conducted a series of experiments at various deposition temperatures ranging from 20 to 90 °C. The resulting films were characterized by AFM, SEM, and VPFM to determine their structure and roughness. Film roughness first decreased and then increased with the increase of deposition temperature. Electrical performance was also characterized and obviously improved insulating property was obtained from the films deposited between 50 and 70 °C. By temperature control during film deposition, it is convenient to efficiently fabricate ferroelectric/semiconducting blend films with good electrical bistability.

  6. Coherent phonon dynamics in semiconducting carbon nanotubes: a quantitative study of electron-phonon coupling.

    Science.gov (United States)

    Lüer, Larry; Gadermaier, Christoph; Crochet, Jared; Hertel, Tobias; Brida, Daniele; Lanzani, Guglielmo

    2009-03-27

    We excite and detect coherent phonons in semiconducting (6,5) carbon nanotubes via a sub-10-fs pump-probe technique. Simulation of the amplitude and phase profile via time-dependent wave packet theory yields excellent agreement with experimental results under the assumption of molecular excitonic states and allows determining the electron-phonon coupling strength for the two dominant vibrational modes.

  7. Polyazines and Polyazomethines with Didodecylthiophene Units for Selective Dispersion of Semiconducting Single-Walled Carbon Nanotubes

    NARCIS (Netherlands)

    Gomulya, Widianta; Derenskyi, Vladimir; Kozma, Erika; Pasini, Mariacecilia; Loi, Maria Antonietta

    2015-01-01

    Polymer wrapped single-walled carbon nanotubes (SWNTs) have been demonstrated to be a very effi cient technique to obtain high purity semiconducting SWNT solutions. However, the extraction yield of this technique is low compared to other techniques. Poly-alkyl-thiophenes have been reported to show h

  8. Nanoscale structuring of semiconducting molecular blend films in the presence of mobile counterions

    NARCIS (Netherlands)

    Heier, J.; Groenewold, J.; Huber, S.; Nüesch, F.; Hany, R.

    2008-01-01

    The controlled fabrication of submicrometer phase-separated morphologies of semiconducting organic materials is attracting considerable interest, for example, in emerging thin-film optoelectronic device applications. For thin films of spin-coated blends of PCBM ([6,6]-phenyl-C61-butyric acid methyl

  9. Highly Efficient and Scalable Separation of Semiconducting Carbon Nanotubes via Weak Field Centrifugation

    Science.gov (United States)

    Reis, Wieland G.; Weitz, R. Thomas; Kettner, Michel; Kraus, Alexander; Schwab, Matthias Georg; Tomović, Željko; Krupke, Ralph; Mikhael, Jules

    2016-05-01

    The identification of scalable processes that transfer random mixtures of single-walled carbon nanotubes (SWCNTs) into fractions featuring a high content of semiconducting species is crucial for future application of SWCNTs in high-performance electronics. Herein we demonstrate a highly efficient and simple separation method that relies on selective interactions between tailor-made amphiphilic polymers and semiconducting SWCNTs in the presence of low viscosity separation media. High purity individualized semiconducting SWCNTs or even self-organized semiconducting sheets are separated from an as-produced SWCNT dispersion via a single weak field centrifugation run. Absorption and Raman spectroscopy are applied to verify the high purity of the obtained SWCNTs. Furthermore SWCNT - network field-effect transistors were fabricated, which exhibit high ON/OFF ratios (105) and field-effect mobilities (17 cm2/Vs). In addition to demonstrating the feasibility of high purity separation by a novel low complexity process, our method can be readily transferred to large scale production.

  10. Method of forming semiconducting amorphous silicon films from the thermal decomposition of fluorohydridodisilanes

    Science.gov (United States)

    Sharp, Kenneth G.; D'Errico, John J.

    1988-01-01

    The invention relates to a method of forming amorphous, photoconductive, and semiconductive silicon films on a substrate by the vapor phase thermal decomposition of a fluorohydridodisilane or a mixture of fluorohydridodisilanes. The invention is useful for the protection of surfaces including electronic devices.

  11. Structure of phase-separated ferroelectric/ semiconducting polymer blends for organic non-volatile memories

    NARCIS (Netherlands)

    Mcneill, C.R.; Asadi, K.; Watts, B.; Blom, P.W.M.; Leeuw, D.M. de

    2010-01-01

    The phase-separated structure of blends of the ferroelectric polymer P(VDF-TrFE) and the semiconducting polymer P3HT used in organic non-volatile memories is revealed with soft X-ray spectromicroscopy. These thin-film blends show a columnar morphology, with P3HT-rich columns enclosed in a continuous

  12. Polarization-induced renormalization of molecular levels at metallic and semiconducting surfaces

    DEFF Research Database (Denmark)

    García Lastra, Juan Maria; Rostgaard, Carsten; Rubio, A.

    2009-01-01

    On the basis of first-principles G0W0 calculations we systematically study how the electronic levels of a benzene molecule are renormalized by substrate polarization when physisorbed on different metallic and semiconducting surfaces. The polarization-induced reduction in the energy gap between...

  13. Selecting Semiconducting Single-Walled Carbon Nanotubes with Narrow Bandgap Naphthalene Diimide-Based Polymers

    NARCIS (Netherlands)

    Salazar-Rios, Jorge Mario; Gomulya, Widianta; Derenskyi, Vladimir; Yang, Jie; Bisri, Satria Zulkarnaen; Chen, Zhihua; Facchetti, Antonio; Loi, Maria Antonietta

    2015-01-01

    Noncovalent functionalization of carbon nanotubes by wrapping them using pi-conjugated polymers is one of the most promising techniques to sort, separate, and purify semiconducting nanotube species for applications in optoelectronic devices. However, wide energy bandgap polymers commonly used in thi

  14. Characterization of asymmetric electron and hole transport in a high-mobility semiconducting polymer

    Science.gov (United States)

    Wang, Liguo; Wang, Xinliang; Liu, Mengli; Cheng, Lingfei

    2017-01-01

    The electron and hole transport properties in a high-mobility n-type copolymer poly{[ N, N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diy1]-alt-5,5'-(2,2'-dithiophene)}[P(NDI2OD-T2), PolyeraActivInk™ N2200] are investigated. The electron mobility is observed to be more than two orders of magnitude higher than the hole mobility. The thickness-dependent current density versus voltage ( J- V) characteristics of N2200 electron-only and hole-only devices cannot be well described using the conventional mobility model. However, the thickness-dependent and temperature-dependent J- V characteristics of N2200 electron-only and hole-only devices can be accurately described using our recently introduced improved mobility model only with a single set of parameters. Within the improved model, the mobility depends on three important physical quantities: the temperature, carrier density, and electric field. For the semiconducting polymer studied, we find the width of the Gaussian density of states σ = 0.082 eV and the lattice constant a = 0.8 nm for electron transport, while the width of the Gaussian density of states σ = 0.11 eV and the lattice constant a = 0.8 nm for hole transport. It is clear that hole transport exhibits a significantly stronger disorder than electron transport. This is also reflected in the lower hole mobility, as compared to the electron mobility.

  15. Novel Electrical and Optoelectronic Characterization Methods for Semiconducting Nanowires and Nanotubes

    Science.gov (United States)

    Katzenmeyer, Aaron Michael

    As technology journalist David Pogue recounted, "If everything we own had improved over the last 25 years as much as electronics have, the average family car would travel four times faster than the space shuttle; houses would cost 200 bucks." The electronics industry is one which, through Moore's Law, created a self-fulfilling prophecy of exponential advancement. This progress has made unforeseen technologies commonplace and revealed new physical understanding of the world in which we live. It is in keeping with these trends that the current work is motivated. This dissertation focuses on the advancement of electrical and optoelectronic characterization techniques suitable for understanding the underlying physics and applications of nanoscopic devices, in particular semiconducting nanowires and nanotubes. In this work an in situ measurement platform based on a field-emission scanning electron microscope fitted with an electrical nanoprobe is shown to be a robust instrument for determining fundamental aspects of nanowire systems (i.e. the dominant mode of carrier transport and the nature of the electrical contacts to the nanowire). The platform is used to fully classify two distinct systems. In one instance it is found that indium arsenide nanowires display space-charge-limited transport and are contacted Ohmically. In the other, gallium arsenide nanowires are found to sequentially show the trap-mediated transport regimes of Poole-Frenkel effect and phonon-assisted tunneling. The contacts in this system are resolved to be asymmetric -- one is Ohmic while the other is a Schottky barrier. Additionally scanning photocurrent microscopy is used to spatially resolve optoelectronic nanowire and nanotube devices. In core/shell gallium arsenide nanowire solar cell arrays it is shown that each individual nanowire functions as a standalone solar cell. Nanotube photodiodes are mapped by scanning photocurrent microscopy to confirm an optimal current collection scheme has been

  16. The Development of Plasma Thrusters and Its Importance for Space Technology and Science Education at University of Brasilia

    Science.gov (United States)

    Ferreira, Jose Leonardo; Calvoso, Lui; Gessini, Paolo; Ferreira, Ivan

    Since 2004 The Plasma Physics Laboratory of University of Brasilia (Brazil) is developing Hall Plasma Thurusters for Satellite station keeping and orbit control. The project is supported by CNPq, CAPES, FAP DF and from The Brazillian Space Agency-AEB. The project is part of The UNIESPAÇO Program for Space Activities Development in Brazillian Universities. In this work we are going to present the highlights of this project together with its vital contribution to include University of Brasilia in the Brazillian Space Program. Electric propulsion has already shown, over the years, its great advantages in being used as main and secondary thruster system of several space mission types. Between the many thruster concepts, one that has more tradition in flying real spacecraft is the Hall Effect Thruster (HET). These thrusters, first developed by the USSR in the 1960s, uses, in the traditional design, the radial magnetic field and axial electric field to trap electrons, ionize the gas and accelerate the plasma to therefore generate thrust. In contrast to the usual solution of using electromagnets to generate the magnetic field, the research group of the Plasma Physics Laboratory of University of Brasília has been working to develop new models of HETs that uses combined permanent magnets to generate the necessary magnetic field, with the main objective of saving electric power in the final system design. Since the beginning of this research line it was developed and implemented two prototypes of the Permanent Magnet Hall Thruster (PMHT). The first prototype, called P-HALL1, was successfully tested with the using of many diagnostics instruments, including, RF probe, Langmuir probe, Ion collector and Ion energy analyzer. The second prototype, P-HALL2, is currently under testing, and it’s planned the increasing of the plasma diagnostics and technology analysis, with the inclusion of a thrust balance, mass spectroscopy and Doppler broadening. We are also developing an

  17. Characterization of the medically important yeast Trichosporon mucoides and its close sister Trichosporon dermatis by traditional and advanced technologies.

    Science.gov (United States)

    Suh, Sung-Oui; Houseknecht, Janice L; Grosso, Kendra M; Carrion, Miguel E

    2015-10-01

    Trichosporon dermatis is a causative agent of several mycoses in immunocompromised patients but is often misidentified as Trichosporon mucoides due to their phenotypic resemblance. In order to evaluate the current identification keys for these species and to develop a rapid and reliable identification method, 11 strains of these yeasts were fully characterized in this study by traditional and advanced technologies. DNA sequences of the internal transcribed spacer (ITS), IGS1, and D1/D2 regions identified six of the yeasts as T. dermatis that were previously known as T. mucoides, including ATCC 204094 that has been used as the quality-control strain of T. mucoides for the VITEK 2 system and other commercial yeast identification kits. These two species could not be differentiated reliably by any previously known phenotypic keys for the species, such as growth patterns on ethylamine, phloroglucinol and tyramine, or by the VITEK 2 system. On the other hand, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) proved to be a rapid and reliable identification tool for the two closely related yeasts. With newly added superspectra from fully authenticated reference strains, the VITEK MS system using MALDI-TOF MS successfully separated strains of T. dermatis and T. mucoides at a similarity level of approximately 67 % for the mass spectra data, and could identify these strains at the species level with 100 % accuracy in repeated tests. Furthermore, the in vitro susceptibility results indicated that itraconazole, posaconazole and voriconazole were more effective against both T. mucoides and T. dermatis than the other antifungal agents tested in this study.

  18. Relationship between concentration of health important groups of fatty acids and components and technological properties in cow milk

    Directory of Open Access Journals (Sweden)

    Oto Hanuš

    2010-01-01

    Full Text Available Groups of fatty acids (FAs in milk fat can have positive and negative impact on consumer health. Profile of FAs could be influenced by dairy cow nutrition, breed, milk yield level et cetera. The question is what relationships the FAs could have to quality of milk products? Relationships between FAs and their groups to selected milk indicators were studied in Czech Fleckvieh and Holstein cows (64 bulk milk samples. There were 8 herds in 2-year investigation during winter and summer season. The relationship of saturated FAs (SAFA; 66.22% was significant only to lactose (L content (0.290; P < 0.05. The relationships of monounsaturated FAs (MUFA; 29.21% to milk indicators (MIs were in­si­gni­fi­cant (P > 0.05. The relationships of polyunsaturated FAs (PUFA, beneficial for consumer health; 4.53% to MIs were narrower: fat (T, 0.321; P < 0.05; lactose (L, 0.458; P < 0.01; milk alcohol stability (AL, 0.447; P < 0.01; titration acidity (SH, 0.342; P < 0.01; cheese curd quality (KV, 0.427; P < 0.01; milk fermentationability (JSH, 0.529; P < 0.001, streptococci count in yoghurt (Strepto, 0.316; P < 0.05; total count of noble bacteria in yoghurt (CPMUK, 0.314; P < 0.05; streptococci/lactobacilly ratio (StreptoLacto, 0.356; P < 0.01. The relationships of conjugated linoleic acid (CLA; markedly beneficial for health; 0.68% to MIs were: T (0.379; P < 0.01; L (–0.542; P < 0.001; AL (0.266; P < 0.05; KV (0.411; P < 0.01; Strepto (0.260; P < 0.05; StreptoLacto (0.270; P < 0.05. The higher CLA levels were connected in this way with: higher fat content; lower lactose content; lower alcohol stability; lower streptococci count in yoghurt; lower streptococci/lactobacilly ratio in yoghurt. The PUFA and CLA representation decreased with L increase. Simultaneously some technological milk properties such as alcohol sta­bi­li­ty and fermentationability were slightly improved.

  19. Spectroscopic properties of doped and defective semiconducting oxides from hybrid density functional calculations.

    Science.gov (United States)

    Di Valentin, Cristiana; Pacchioni, Gianfranco

    2014-11-18

    CONSPECTUS: Very rarely do researchers use metal oxides in their pure and fully stoichiometric form. In most of the countless applications of these compounds, ranging from catalysis to electronic devices, metal oxides are either doped or defective because the most interesting chemical, electronic, optical, and magnetic properties arise when foreign components or defects are introduced in the lattice. Similarly, many metal oxides are diamagnetic materials and do not show a response to specific spectroscopies such as electron paramagnetic resonance (EPR) spectroscopy. However, doped or defective oxides may exhibit an interesting and informative paramagnetic behavior. Doped and defective metal oxides offer an expanding range of applications in contemporary condensed matter science; therefore researchers have devoted enormous effort to the understanding their physical and chemical properties. The interplay between experiment and computation is particularly useful in this field, and contemporary simulation techniques have achieved high accuracies with these materials. In this Account, we show how the direct comparison between spectroscopic experimental and computational data for some selected and relevant materials provides ways to understand and control these complex systems. We focus on the EPR properties and electronic transitions that arise from the presence of dopants and defects in bulk metal oxide materials. We analyze and compare the effect of nitrogen doping in TiO2 and ZnO (two semiconducting oxides) and MgO (a wide gap insulator) and examine the effect of oxygen deficiency in the semiconducting properties of TiO2-x, ZnO1-x, and WO3-x materials. We chose these systems because of their relevance in applications including photocatalysis, touch screens, electrodes in magnetic random access memories, and smart glasses. Density functional theory (DFT) provides the general computational framework used to illustrate the electronic structure of these systems. However

  20. Direct intermolecular force measurements between functional groups and individual metallic or semiconducting single-walled carbon nanotubes.

    Science.gov (United States)

    Thong, Ya Xuan; Poon, Yin Fun; Chen, Tzu-Yin; Li, Lain-Jong; Chan-Park, Mary B

    2014-02-26

    Many electronic applications of single-walled carbon nanotubes (SWNTs) require electronic homogeneity in order to maximally exploit their outstanding properties. Non-covalent separation is attractive as it is scalable and results in minimal alteration of nanotube properties. However, fundamental understanding of the metallicity-dependence of functional group interactions with nanotubes is still lacking; this lack is compounded by the absence of methods to directly measure these interactions. Herein, a novel technology platform based on a recently developed atomic force microscopy (AFM) mode is reported which directly quantifies the adhesion forces between a chosen functional group and individual nanotubes of known metallicity, permitting comparisons between different metallicity. These results unambiguously show that this technology platform is able to discriminate the subtle adhesion force differences of a chosen functional group with pure metallic as opposed to pure semiconducting nanotubes. This new method provides a route towards rapid advances in understanding of non-covalent interactions of large libraries of compounds with nanotubes of varying metallicity and diameter; presenting a superior tool to assist the discovery of more effective metallicity-based SWNT separation agents.

  1. African fermented dairy products - Overview of predominant technologically important microorganisms focusing on African Streptococcus infantarius variants and potential future applications for enhanced food safety and security.

    Science.gov (United States)

    Jans, Christoph; Meile, Leo; Kaindi, Dasel Wambua Mulwa; Kogi-Makau, Wambui; Lamuka, Peter; Renault, Pierre; Kreikemeyer, Bernd; Lacroix, Christophe; Hattendorf, Jan; Zinsstag, Jakob; Schelling, Esther; Fokou, Gilbert; Bonfoh, Bassirou

    2017-06-05

    Milk is a major source of nutrients, but can also be a vehicle for zoonotic foodborne diseases, especially when raw milk is consumed. In Africa, poor processing and storage conditions contribute to contamination, outgrowth and transmission of pathogens, which lead to spoilage, reduced food safety and security. Fermentation helps mitigate the impact of poor handling and storage conditions by enhancing shelf life and food safety. Traditionally-fermented sour milk products are culturally accepted and widely distributed in Africa, and rely on product-specific microbiota responsible for aroma, flavor and texture. Knowledge of microbiota and predominant, technologically important microorganisms is critical in developing products with enhanced quality and safety, as well as sustainable interventions for these products, including Africa-specific starter culture development. This narrative review summarizes current knowledge of technologically-important microorganisms of African fermented dairy products (FDP) and raw milk, taking into consideration novel findings and taxonomy when re-analyzing data of 29 publications covering 25 products from 17 African countries. Technologically-important lactic acid bacteria such as Lactococcus lactis and Streptococcus infantarius subsp. infantarius (Sii), Lactobacillus spp. and yeasts predominated in raw milk and FDP across Africa. Re-analysis of data also suggests a much wider distribution of Sii and thus a potentially longer history of use than previously expected. Therefore, evaluating the role and safety of African Sii lineages is important when developing interventions and starter cultures for FDP in Africa to enhance food safety and food security. In-depth functional genomics, epidemiologic investigations and latest identification approaches coupled with stakeholder involvement will be required to evaluate the possibility of African Sii lineages as novel food-grade Streptococcus lineage. Copyright © 2017 The Authors. Published by

  2. Transition of single-walled carbon nanotubes from metallic to semiconducting in field-effect transistors by hydrogen plasma treatment.

    Science.gov (United States)

    Zheng, Gang; Li, Qunqing; Jiang, Kaili; Zhang, Xiaobo; Chen, Jia; Ren, Zheng; Fan, Shoushan

    2007-06-01

    We report hydrogen plasma treatment results on converting the metallic single-walled carbon nanotubes to semiconducting single-walled carbon nanotubes. We found that the as-grown single-walled carbon nanotubes (SWNTs) can be sorted as three groups which behave as metallic, as-metallic, and semiconducting SWNTs. These three groups have different changes under hydrogen plasma treatment and successive annealing process. The SWNTs can be easily hydrogenated in the hydrogen plasma environment and the as-metallic SWNTs can be transformed to semiconducting SWNTs. The successive annealing process can break the C-H bond, so the conversion is reversible.

  3. Surface Chemistry of Semiconducting Quantum Dots: Theoretical Perspectives.

    Science.gov (United States)

    Kilina, Svetlana V; Tamukong, Patrick K; Kilin, Dmitri S

    2016-10-18

    Colloidal quantum dots (QDs) are near-ideal nanomaterials for energy conversion and lighting technologies. However, their photophysics exhibits supreme sensitivity to surface passivation and defects, of which control is problematic. The role of passivating ligands in photodynamics remains questionable and is a focus of ongoing research. The optically forbidden nature of surface-associated states makes direct measurements on them challenging. Therefore, computational modeling is imperative for insights into surface passivation and its impact on light-driven processes in QDs. This Account discusses challenges and recent progress in understanding surface effects on the photophysics of QDs addressed via quantum-chemical calculations. We overview different methods, including the effective mass approximation (EMA), time-dependent density functional theory (TDDFT), and multiconfiguration approaches, considering their strengths and weaknesses relevant to modeling of QDs with a complicated surface. We focus on CdSe, PbSe, and Si QDs, where calculations successfully explain experimental trends sensitive to surface defects, doping, and ligands. We show that the EMA accurately describes both linear and nonlinear optical properties of large-sized CdSe QDs (>2.5 nm), while TDDFT is required for smaller QDs where surface effects dominate. Both approaches confirm efficient two-photon absorption enabling applications of QDs as nonlinear optical materials. TDDFT also describes the effects of morphology on the optical response of QDs: the photophysics of stoichiometric, magic-sized XnYn (X = Cd, Pb; Y = S, Se) QDs is less sensitive to their passivation compared with nonstoichiometric Xn≠mYm QDs. In the latter, surface-driven optically inactive midgap states can be eliminated by anionic ligands, explaining the better emission of metal-enriched QDs compared with nonmetal-enriched QDs. Ideal passivation of magic-sized QDs by amines and phosphine oxides leaves lower-energy transitions

  4. Analytic Hierarchy Process to Define the Most Important Factors and Related Technologies for Empowering Elderly People in Taking an Active Role in their Health.

    Science.gov (United States)

    Fico, G; Gaeta, E; Arredondo, M T; Pecchia, L

    2015-09-01

    Successful management of health conditions in older population is determined by strategic involvement of a professional team of careers and by empowering patients and their caregivers to take over a central role and responsibility in the daily management of condition. Identifying, structuring and ranking the most important needs related to these aspects could pave the way for improved strategies in designing systems and technological solutions supporting user empowerment. This paper presents the preliminary results of a study aiming to elicit these needs. Healthcare professionals, working together in the European and Innovation Partnership on Active and Healthy Ageing (EIP-AHA) initiative, have defined a set of needs and factors that have been organized in two hierarchies around the concepts of patient activation and proactive and prepared care team, defined in the Chronic Care Model. The two hierarchies have been mapped, by a team of experts in computer science, with technologies and solutions that could facilitate the achievement of the identified needs.

  5. Semiconducting Graphene on Silicon from First-Principles Calculations.

    Science.gov (United States)

    Dang, Xuejie; Dong, Huilong; Wang, Lu; Zhao, Yanfei; Guo, Zhenyu; Hou, Tingjun; Li, Youyong; Lee, Shuit-Tong

    2015-08-25

    Graphene is a semimetal with zero band gap, which makes it impossible to turn electric conduction off below a certain limit. Transformation of graphene into a semiconductor has attracted wide attention. Owing to compatibility with Si technology, graphene adsorbed on a Si substrate is particularly attractive for future applications. However, to date there is little theoretical work on band gap engineering in graphene and its integration with Si technology. Employing first-principles calculations, we study the electronic properties of monolayer and bilayer graphene adsorbed on clean and hydrogen (H)-passivated Si (111)/Si (100) surfaces. Our calculation shows that the interaction between monolayer graphene and a H-passivated Si surface is weak, with the band gap remaining negligible. For bilayer graphene adsorbed onto a H-passivated Si surface, the band gap opens up to 108 meV owing to asymmetry introduction. In contrast, the interaction between graphene and a clean Si surface is strong, leading to formation of chemical bonds and a large band gap of 272 meV. Our results provide guidance for device designs based on integrating graphene with Si technology.

  6. Empirical Equation Based Chirality (n, m Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

    Directory of Open Access Journals (Sweden)

    Md Shamsul Arefin

    2012-12-01

    Full Text Available This work presents a technique for the chirality (n, m assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n, m with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot.

  7. Empirical Equation Based Chirality (n, m) Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

    Science.gov (United States)

    Arefin, Md Shamsul

    2012-01-01

    This work presents a technique for the chirality (n, m) assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n− m) with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m) of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot.

  8. High resolution backscattering studies of nanostructured magnetic and semiconducting materials

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, A. [Instituto Tecnologico e Nuclear, Dept. Fisica, Estrada Nac. 10, 2686-953 Sacavem (Portugal)]. E-mail: afonseca@itn.pt; Franco, N. [Instituto Tecnologico e Nuclear, Dept. Fisica, Estrada Nac. 10, 2686-953 Sacavem (Portugal); Alves, E. [Instituto Tecnologico e Nuclear, Dept. Fisica, Estrada Nac. 10, 2686-953 Sacavem (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Barradas, N.P. [Instituto Tecnologico e Nuclear, Dept. Fisica, Estrada Nac. 10, 2686-953 Sacavem (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Leitao, J.P. [Departamento de Fisica da Universidade de Aveiro, 3810-193 Aveiro (Portugal); Sobolev, N.A. [Departamento de Fisica da Universidade de Aveiro, 3810-193 Aveiro (Portugal); Banhart, D.F. [Z. E. Elektronenmikroskopie, Universitaet Ulm, Albert-Einstein-Allee 11, D-89069 Ulm (Germany); Presting, H. [Daimler-Chrysler Forschungszentrum, 89081 Ulm (Germany); Ulyanov, V.V. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation); Nikiforov, A.I. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation)

    2005-12-15

    Low dimension structures raises inevitably new technological challenges in materials science. The new structures must fulfill stringent requirements in composition, crystalline quality and interface sharpness among others. We present and discuss the results of Si/Ge quantum structures and FePt/C multilayer structures deposited at different temperatures by ion beam sputtering. Evidence for the presence of FePt nanoparticles embedded in the C matrix and Ge islands in Ge/Si multilayers structures was found. Size and stoichiometry of the nanoparticles and the multilayer periodicity was obtained using Rutherford backscattering at grazing angles of incidence. The strain state of the single crystalline layers was determined by tilt axis channelling.

  9. Photoelectric Property Modulation by Nanoconfinement in the Longitude Direction of Short Semiconducting Nanorods.

    Science.gov (United States)

    Tang, Chaolong; Jiang, Chengming; Bi, Sheng; Song, Jinhui

    2016-05-01

    Photoelectric property change in half-dimensional (0.5D) semiconducting nanomaterials as a function of illumination light intensity and materials geometry has been systematically studied. Through two independent methods, conductive atomic force microscopy (C-AFM) direct current-voltage acquisition and scanning kelvin probe microscopy (SKPM) surface potential mapping, photoelectric property of 0.5D ZnO nanomaterial has been characterized with exceptional behaviors compared with bulk/micro/one-dimensional (1D) nanomaterial. A new model by considering surface effect, quantum effect, and illumination effect has been successfully built, which could more accurately predict the photoelectric characteristics of 0.5D semiconducting nanomaterials. The findings reported in this study could potentially impact three-dimensional (3D) photoelectronics.

  10. Preparation and Photoelectric Conversion Mechanism of Semiconducting ITO/Cu2O Electrodes

    Institute of Scientific and Technical Information of China (English)

    WANG Hua; HE Wei; WANG Hui-xiu; WANG Shou-xu

    2006-01-01

    Semiconducting cuprous oxide films were electrodeposited onto conducting glasses coated with Indium Tin Oxide (ITO) using potentiostatic method. The electrodes were examined by means of X-Ray Diffraction (XRD) and X-ray Photoelectron Spectrum (XPS). The results indicate that the prepared films are cubic Cu2O crystals, and annealing enhances the size and preferred orientation of the films. The photoelectric conversion mechanism of semiconducting ITO/Cu2O electrodes in 0.1 mol/L potassium sulfate (K2SO4) solution is further discussed by using Linear Sweep Voltammetry (LSV) method. The differences of photoelectric conversion of electrodes are reasonably deduced and proved through surfactant modifying, annealing or not, respectively.

  11. Exciton States and Linear Optical Spectra of Semiconducting Carbon Nanotubes under Uniaxial Strain

    Institute of Scientific and Technical Information of China (English)

    YU Gui-Li; JIA Yong-Lei

    2009-01-01

    Considering the exciton effect,the linear optical spectra of semiconducting single-walled carbon nanotubes (SWNTs) under uniaxial strain are theoretically studied by using the standard formulae of Orr and Ward [Mol.Phys.20(1971)513].It is found that due to the wrapping effect existing in the semiconducting zigzag tubes,the excitation energies of the linear optical spectra show two different kinds of variations with increasing uniaxial strain,among which one decreases such as tube (11,0),and the other increases firstly and then decreases such as tube (10,0).These variations of the linear optical spectra are consistent with the changes of the exciton binding energies or the (quasi)continuum edge of these SWNTs calculated in our previous work,which can be used as a supplemented tool to detect the deformation degree of an SWNT under uniaxiai strain.

  12. Linear ac transport in graphene semiconducting nanosystem with normal-metal electrodes

    Science.gov (United States)

    Ye, En-Jia; Sun, Yun-Lei; Lan, Jin; Shi, Yi-Jian

    2016-03-01

    Linear ac transport properties are investigated in a graphene semiconducting nanosystem, with the effect of normal-metal electrodes taken into account. We use a tight-binding approach and ac transport theory to study the dc conductance and ac emittance in normal-metal/graphene (NG) and normal-metal/graphene/normal-metal (NGN) systems with armchair-edge graphene. We find that the resonant and semiconducting behaviors in NG and NGN systems are closely related to the spatial-resolved local density of states. Furthermore, features of the size-dependent emittances in the NGN system are investigated. The results suggest a positive correlation between the width and capacitive response, and the capacitive response is robust as the size of the system increases proportionally.

  13. Scintillation properties of semiconducting 6LiInSe2 crystals to ionizing radiation

    Science.gov (United States)

    Wiggins, Brenden; Groza, Michael; Tupitsyn, Eugene; Lukosi, Eric; Stassun, Keivan; Burger, Arnold; Stowe, Ashley

    2015-11-01

    6LiInSe2 has gained attention recently as a semiconducting thermal neutron detector. As presented herein, the chalcogenide compound semiconductor also detects incident neutrons via scintillation, making 6LiInSe2 the only lithium containing semiconductor to respond to neutrons via both detection mechanisms. Both yellow and red crystals, which appear in the literature, were investigated. Only the yellow crystal responded favorably to ionizing radiation, similar to the semiconducting operation utilizing electrodes. The obtained light yield for yellow crystals is 4400 photons/MeV, referenced to Bi4Ge3O12 (BGO).The estimated thermal neutron light yield was 21,000 photons/thermal neutron. The two measured decay time components were found to be 31±1 ns (49%) and 143±9 ns (51%).This crystal provides efficient, robust detection of neutrons via scintillation with respectable light yield and rapid response, enabling its use for a broad array of neutron detection applications.

  14. Technology.

    Science.gov (United States)

    Online-Offline, 1998

    1998-01-01

    Focuses on technology, on advances in such areas as aeronautics, electronics, physics, the space sciences, as well as computers and the attendant progress in medicine, robotics, and artificial intelligence. Describes educational resources for elementary and middle school students, including Web sites, CD-ROMs and software, videotapes, books,…

  15. Vacancy Induced Energy Band Gap Changes of Semiconducting Zigzag Single Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    DERELI, G.

    2017-08-01

    Full Text Available In this work, we have examined how the multi-vacancy defects induced in the horizontal direction change the energetics and the electronic structure of semiconducting Single-Walled Carbon Nanotubes (SWCNTs. The electronic structure of SWCNTs is computed for each deformed configuration by means of real space, Order(N Tight Binding Molecular Dynamic (O(N TBMD simulations. Energy band gap is obtained in real space through the behavior of electronic density of states (eDOS near the Fermi level. Vacancies can effectively change the energetics and hence the electronic structure of SWCNTs. In this study, we choose three different kinds of semiconducting zigzag SWCNTs and determine the band gap modifications. We have selected (12,0, (13,0 and (14,0 zigzag SWCNTs according to n (mod 3 = 0, n (mod 3 = 1 and n (mod 3 = 2 classification. (12,0 SWCNT is metallic in its pristine state. The application of vacancies opens the electronic band gap and it goes up to 0.13 eV for a di-vacancy defected tube. On the other hand (13,0 and (14,0 SWCNTs are semiconductors with energy band gap values of 0.44 eV and 0.55 eV in their pristine state, respectively. Their energy band gap values decrease to 0.07 eV and 0.09 eV when mono-vacancy defects are induced in their horizontal directions. Then the di-vacancy defects open the band gap again. So in both cases, the semiconducting-metallic ¬- semiconducting transitions occur. It is also shown that the band gap modification exhibits irreversible characteristics, which means that band gap values of the nanotubes do not reach their pristine values with increasing number of vacancies.

  16. Chain-Growth Methods for the Synthesis of High Molecular Weight Conducting and Semiconducting Polymers

    Science.gov (United States)

    2013-08-25

    AFOSR-Final Report Award FA9550-10-1-0395, "Chain-Growth Methods for the Synthesis of High Molecular Weight Conducting and Semiconducting...blocked with further substitution of the fulvene ring systems and we conducted detailed characterization of these systems (X-ray crystal structures...Living Chain-Growth Polymerization for Polythiophenes We have also developed a powerful new method for the synthesis of polythiophenes through the

  17. Titania nanotubes self-assembled by electrochemical anodization: Semiconducting and electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Giorgi, L., E-mail: leonardo_giorgi@libero.it [Materials Science & Electrochemistry, Via Mantova 11, 00042, Anzio, Roma (Italy); Salernitano, E. [ENEA, Faenza Laboratories, Via Ravegnana 186, 48018 Faenza, Ravenna (Italy); Dikonimos Makris, Th.; Giorgi, R.; Leoni, E.; Grilli, M.L.; Lisi, N. [ENEA, Casaccia Research Centre, Via Anguillarese 301, 00123, S. Maria di Galeria, Roma (Italy)

    2016-02-29

    Titania nanotubes (TNT), thanks to their semiconducting properties, have received wide attention for application in many fields such as photoelectrolysis, dye sensitized solar cells, photocatalysis, and sensors. In this work, highly ordered TNT were grown by controlled electrochemical anodization of titanium sheets. Scanning electron microscope equipped with a field emission gun and electrochemical DC/AC techniques was used to characterize the TNT. Semiconducting properties were investigated through linear sweep voltammetry and electrochemical impedance spectroscopy. Donor concentration (N{sub ed}) was obtained by recording Mott–Schottky plots. The high N{sub ed} of TNT (around 10{sup 26} m{sup −3}) allows an optimal electron transfer when used as photoelectrode. Frequency dispersion of flat band potential from Mott–Schottky plots (− 0.38 ÷ + 0.40 V vs. saturated calomel electrode, SCE) was used as an indicator of the amorphous semiconductor behaviour. The dispersion of flat band in heat treated samples was extremely reduced (0.48–0.51 V vs. SCE) because of the conversion to crystalline semiconductor. The depth of space charge was comparable to the TNT wall thickness, meaning that the entire TiO{sub 2} nanotube walls formed the space charge layer. Considering the high charge carrier concentration, we can hypothesise a high density of electronic defects (e.g., surface states) that enhances the electron transport by percolation inside a porous photoelectrode. The transition from amorphous to crystalline structure of TNT was detected from the change of semiconducting properties and confirmed by Raman spectroscopy. - Highlights: • Highly ordered self-assembled TiO{sub 2} nanotubes were synthesized by electrochemical anodization. • The electrochemical and semiconducting properties were studied. • An electrical model was developed for titania nanotubes/electrolyte interface. • Thermal treatment changed electronic properties of TiO{sub 2} nanotubes.

  18. Theory and it ab initio calculation of radiative lifetime of excitons in semiconducting carbon nanotubes

    OpenAIRE

    Spataru, Catalin D.; Ismail-Beigi, Sohrab; Capaz, Rodrigo B.; Louie, Steven G.

    2005-01-01

    We present theoretical analysis and first-principles calculation of the radiative lifetime of excitons in semiconducting carbon nanotubes. An intrinsic lifetime of the order of 10 ps is computed for the lowest optically active bright excitons. The intrinsic lifetime is however a rapid increasing function of the exciton momentum. Moreover, the electronic structure of the nanotubes dictates the existence of dark excitons nearby in energy to each bright exciton. Both effects strongly influence m...

  19. Heat-Activated Effect of Exchange Coupling Between Two Ferromagnets Separated by an Amorphous Semiconducting Barrier

    Institute of Scientific and Technical Information of China (English)

    肖明文; 李正中; 许望

    2002-01-01

    We try to extend our previous zero-temperature tunnelling theory for the exchange coupling between two ferromagnets separated by an amorphous semiconducting barrier to the case of finite temperature. The result exhibits that the tunnelling electrons can absorb or emit phonons when they tunnel through the amorphous barrier at finite temperatures so that the interlayer exchange coupling is heat activated. This agrees with the experiments.

  20. Origin of weak ferroelectricity in semiconductive Sb2S3 crystal

    Science.gov (United States)

    Žigas, Leonardas; Audzijonis, Algirdas; Grigas, Jonas

    2017-02-01

    The paper presents the results of the investigations of electronic potential dependencies upon the normal co-ordinates of B1u mode in a large temperature range for the Sb2S3 crystal. The results revealed high anharmonicity of Sb and S atoms in this highly covalent semiconductive compound and B1u - mode polar distortion with temperature leading to appearance of weak ferroelectricity.

  1. Piezo-semiconductive quasi-1D nanodevices with or without anti-symmetry.

    Science.gov (United States)

    Araneo, Rodolfo; Lovat, Giampiero; Burghignoli, Paolo; Falconi, Christian

    2012-09-04

    The piezopotential in floating, homogeneous, quasi-1D piezo-semiconductive nanostructures under axial stress is an anti-symmetric (i.e., odd) function of force. Here, after introducing piezo-nano-devices with floating electrodes for maximum piezo-potential, we show that breaking the anti-symmetric nature of the piezopotential-force relation, for instance by using conical nanowires, can lead to better nanogenerators, piezotronic and piezophototronic devices.

  2. Semiconducting polymer nanoparticles as photoacoustic molecular imaging probes in living mice

    Science.gov (United States)

    Pu, Kanyi; Shuhendler, Adam J.; Jokerst, Jesse V.; Mei, Jianguo; Gambhir, Sanjiv S.; Bao, Zhenan; Rao, Jianghong

    2014-03-01

    Photoacoustic imaging holds great promise for the visualization of physiology and pathology at the molecular level with deep tissue penetration and fine spatial resolution. To fully utilize this potential, photoacoustic molecular imaging probes have to be developed. Here, we introduce near-infrared light absorbing semiconducting polymer nanoparticles as a new class of contrast agents for photoacoustic molecular imaging. These nanoparticles can produce a stronger signal than the commonly used single-walled carbon nanotubes and gold nanorods on a per mass basis, permitting whole-body lymph-node photoacoustic mapping in living mice at a low systemic injection mass. Furthermore, the semiconducting polymer nanoparticles possess high structural flexibility, narrow photoacoustic spectral profiles and strong resistance to photodegradation and oxidation, enabling the development of the first near-infrared ratiometric photoacoustic probe for in vivo real-time imaging of reactive oxygen species--vital chemical mediators of many diseases. These results demonstrate semiconducting polymer nanoparticles to be an ideal nanoplatform for developing photoacoustic molecular probes.

  3. Semiconducting polymer nanoparticles as photoacoustic molecular imaging probes in living mice.

    Science.gov (United States)

    Pu, Kanyi; Shuhendler, Adam J; Jokerst, Jesse V; Mei, Jianguo; Gambhir, Sanjiv S; Bao, Zhenan; Rao, Jianghong

    2014-03-01

    Photoacoustic imaging holds great promise for the visualization of physiology and pathology at the molecular level with deep tissue penetration and fine spatial resolution. To fully utilize this potential, photoacoustic molecular imaging probes have to be developed. Here, we introduce near-infrared light absorbing semiconducting polymer nanoparticles as a new class of contrast agents for photoacoustic molecular imaging. These nanoparticles can produce a stronger signal than the commonly used single-walled carbon nanotubes and gold nanorods on a per mass basis, permitting whole-body lymph-node photoacoustic mapping in living mice at a low systemic injection mass. Furthermore, the semiconducting polymer nanoparticles possess high structural flexibility, narrow photoacoustic spectral profiles and strong resistance to photodegradation and oxidation, enabling the development of the first near-infrared ratiometric photoacoustic probe for in vivo real-time imaging of reactive oxygen species--vital chemical mediators of many diseases. These results demonstrate semiconducting polymer nanoparticles to be an ideal nanoplatform for developing photoacoustic molecular probes.

  4. Nonvolatile Transistor Memory with Self-Assembled Semiconducting Polymer Nanodomain Floating Gates.

    Science.gov (United States)

    Wang, Wei; Kim, Kang Lib; Cho, Suk Man; Lee, Ju Han; Park, Cheolmin

    2016-12-14

    Organic field effect transistor based nonvolatile memory (OFET-NVM) with semiconducting nanofloating gates offers additional benefits over OFET-NVMs with conventional metallic floating gates due to the facile controllability of charge storage based on the energetic structure of the floating gate. In particular, an all-in-one tunneling and floating-gate layer in which the semiconducting polymer nanodomains are self-assembled in the dielectric tunneling layer is promising. In this study, we utilize crystals of a p-type semiconducting polymer in which the crystalline lamellae of the polymer are spontaneously developed and embedded in the tunneling matrix as the nanofloating gate. The widths and lengths of the polymer nanodomains are approximately 20 nm and a few hundred nanometers, respectively. An OFET-NVM containing the crystalline nanofloating gates exhibits memory performance with a large memory window of 10 V, programming/erasing switching endurance for over 500 cycles, and a long retention time of 5000 s. Moreover, the device performance is improved by comixing with an n-type semiconductor; thus, the solution-processed p- and n-type double floating gates capable of storing both holes and electrons allow for the multilevel operation of our OFET-NVM. Four highly reliable levels (two bits per cell) of charge trapping and detrapping are achieved using this OFET-NVM by accurately choosing the programming/erasing voltages.

  5. Production of semiconducting gold-DNA nanowires by application of DC bias.

    Science.gov (United States)

    Joshi, Rakesh K; West, Leigh; Kumar, Amrita; Joshi, Nidhi; Alwarappan, Subbiah; Kumar, Ashok

    2010-05-07

    There is considerable interest in using DNA nanowires or nanotubes in a wide variety of bioelectronic applications and microcircuitry. Various methods have been developed to construct DNA nanostructures. Here, we report a novel method to construct semiconducting DNA nanowires by applying a suitable DC bias to a gold plating solution containing double-stranded DNA. The self-assembled nanowires fabricated by this method contain attached gold nanoparticles. Further, we report that the dimensions of the nanowires can be easily manipulated by altering the applied DC bias. We also confirmed the semiconducting nature of the DNA nanowires by studying their resistance-temperature behavior from 25 to 65 degrees C in a microelectrode system. These studies describe a simple process by which gold-decorated, semiconducting DNA nanowires could be created and may lead to a breakthrough in the field of self-assembly of nanometer-scale circuits. The self-assembled structures do have some similarity with tube-like structures but in the present work we are using the term 'DNA nanowires' to define the structures.

  6. Intrinsic nature of visible-light absorption in amorphous semiconducting oxides

    Directory of Open Access Journals (Sweden)

    Youngho Kang

    2014-03-01

    Full Text Available To enlighten microscopic origin of visible-light absorption in transparent amorphous semiconducting oxides, the intrinsic optical property of amorphous InGaZnO4 is investigated by considering dipole transitions within the quasiparticle band structure. In comparison with the crystalline InGaZnO4 with the optical gap of 3.6 eV, the amorphous InGaZnO4 has two distinct features developed in the band structure that contribute to significant visible-light absorption. First, the conduction bands are down-shifted by 0.55 eV mainly due to the undercoordinated In atoms, reducing the optical gap between extended states to 2.8 eV. Second, tail states formed by localized oxygen p orbitals are distributed over ∼0.5 eV near the valence edge, which give rise to substantial subgap absorption. The fundamental understanding on the optical property of amorphous semiconducting oxides based on underlying electronic structure will pave the way for resolving instability issues in recent display devices incorporating the semiconducting oxides.

  7. Production of semiconducting gold-DNA nanowires by application of DC bias

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Rakesh K; Joshi, Nidhi; Alwarappan, Subbiah; Kumar, Ashok [Nanomaterials and Nanomanufacturing Research Center, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620 (United States); West, Leigh [Florida Center of Excellence for Biomolecular Identification and Targeted Therapeutics, University of South Florida, 3720 Spectrum Boulevard, Suite 324, Tampa, FL 33612 (United States); Kumar, Amrita, E-mail: joshi@usf.edu, E-mail: kumar@usf.edu [Department of Pathology, Emory University School of Medicine, Atlanta, GA 30322 (United States)

    2010-05-07

    There is considerable interest in using DNA nanowires or nanotubes in a wide variety of bioelectronic applications and microcircuitry. Various methods have been developed to construct DNA nanostructures. Here, we report a novel method to construct semiconducting DNA nanowires by applying a suitable DC bias to a gold plating solution containing double-stranded DNA. The self-assembled nanowires fabricated by this method contain attached gold nanoparticles. Further, we report that the dimensions of the nanowires can be easily manipulated by altering the applied DC bias. We also confirmed the semiconducting nature of the DNA nanowires by studying their resistance-temperature behavior from 25 to 65 deg. C in a microelectrode system. These studies describe a simple process by which gold-decorated, semiconducting DNA nanowires could be created and may lead to a breakthrough in the field of self-assembly of nanometer-scale circuits. The self-assembled structures do have some similarity with tube-like structures but in the present work we are using the term 'DNA nanowires' to define the structures.

  8. Wide dynamic range enrichment method of semiconducting single-walled carbon nanotubes with weak field centrifugation.

    Science.gov (United States)

    Reis, Wieland G; Tomović, Željko; Weitz, R Thomas; Krupke, Ralph; Mikhael, Jules

    2017-03-20

    The potential of single-walled carbon nanotubes (SWCNTs) to outperform silicon in electronic application was finally enabled through selective separation of semiconducting nanotubes from the as-synthesized statistical mix with polymeric dispersants. Such separation methods provide typically high semiconducting purity samples with narrow diameter distribution, i.e. almost single chiralities. But for a wide range of applications high purity mixtures of small and large diameters are sufficient or even required. Here we proof that weak field centrifugation is a diameter independent method for enrichment of semiconducting nanotubes. We show that the non-selective and strong adsorption of polyarylether dispersants on nanostructured carbon surfaces enables simple separation of diverse raw materials with different SWCNT diameter. In addition and for the first time, we demonstrate that increased temperature enables higher purity separation. Furthermore we show that the mode of action behind this electronic enrichment is strongly connected to both colloidal stability and protonation. By giving simple access to electronically sorted SWCNTs of any diameter, the wide dynamic range of weak field centrifugation can provide economical relevance to SWCNTs.

  9. Production and distribution of dilute species in semiconducting materials

    Energy Technology Data Exchange (ETDEWEB)

    James, Ralph B.; Camarda, Giuseppe; Bolotnikov, Aleksey E.; Hossain, Anwar; Yang, Ge; Kim, Kihyun

    2016-09-06

    Technologies are described effective to implement systems and methods of producing a material. The methods comprise receiving a tertiary semiconductor sample with a dilute species. The sample has two ends. The first end of the sample includes a first concentration of the dilute species lower than a second concentration of the dilute species in the second end of the sample. The method further comprises heating the sample in a chamber. The chamber has a first zone and a second zone. The first zone having a first temperature higher than a second temperature in the second zone. The sample is orientated such that the first end is in the first zone and the second end is in the second zone.

  10. Understanding and improving the mechanical stability of semiconducting polymers for flexible and stretchable electronics

    Science.gov (United States)

    Printz, Adam David

    Polymeric semiconductors offer the promise of low-cost, printable, and mechanically robust electronic devices for use in outdoor, portable, and wearable applications such as organic photovoltaics, biosensors, and electronic skins. However, many organic semiconductors are unable to accommodate the mechanical stresses these applications require, and it is therefore important to understand the factors and parameters that govern the mechanical stability of these materials. Chapter 1 provides a gentle introduction to the electronic and mechanical properties relevant to flexible and stretchable organic semiconductor devices. The idea of inherent competition between electronic performance and mechanical robustness is explored. Chapter 2 investigates the inherent competition between good electronic performance and mechanical robustness in poly(3-alkylthiophene)s. A key finding is a critical alkyl side-chain length that allows for good electronic performance and mechanical compliance. Chapter 3 and Appendix A are further studies on the properties of poly(3-alkylthiophene)s with side-chains close to the critical length to gain better understanding of the transition from good electronic properties and poor mechanical properties to poor electronic properties and good mechanical properties. Chapter 4 and Appendix B detail the effects on mechanical and electronic properties of statistical incorporation of unlike monomer into a low-bandgap polymer backbone in an effort to disrupt aggregation and improve mechanical compliance. Chapter 5 explores how the extent of molecular mixing of polythiophenes and fullerenes---materials common in organic photovoltaics---affects their mechanical properties. Chapter 6 describes the invention of a new technique to determine the yield point of thin films. A dependence on the alkyl-side chain length is observed, as well as a critical film thickness below which the yield point increases substantially. In Chapter 7, the weakly interacting H

  11. Competition between deformability and charge transport in semiconducting polymers for flexible and stretchable electronics

    Energy Technology Data Exchange (ETDEWEB)

    Printz, Adam D.; Lipomi, Darren J., E-mail: dlipomi@ucsd.edu [Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448 (United States)

    2016-06-15

    The primary goal of the field concerned with organic semiconductors is to produce devices with performance approaching that of silicon electronics, but with the deformability—flexibility and stretchability—of conventional plastics. However, an inherent competition between deformability and charge transport has long been observed in these materials, and achieving the extreme (or even moderate) deformability implied by the word “plastic” concurrently with high charge transport may be elusive. This competition arises because the properties needed for high carrier mobilities—e.g., rigid chains in π-conjugated polymers and high degrees of crystallinity in the solid state—are antithetical to deformability. On the device scale, this competition can lead to low-performance yet mechanically robust devices, or high-performance devices that fail catastrophically (e.g., cracking, cohesive failure, and delamination) under strain. There are, however, some observations that contradict the notion of the mutual exclusivity of electronic and mechanical performances. These observations suggest that this problem may not be a fundamental trade-off, but rather an inconvenience that may be negotiated by a logical selection of materials and processing conditions. For example, the selection of the poly(3-alkylthiophene) with a critical side-chain length—poly(3-heptylthiophene) (n = 7)—marries the high deformability of poly(3-octylthiophene) (n = 8) with the high electronic performance (as manifested in photovoltaic efficiency) of poly(3-hexylthiophene) (n = 6). This review explores the relationship between deformability and charge transport in organic semiconductors. The principal conclusions are that reducing the competition between these two parameters is in fact possible, with two demonstrated routes being: (1) incorporation of softer, insulating material into a stiffer, semiconducting material and (2) increasing disorder in a highly ordered film, but not

  12. Organic ferroelectric/semiconducting nanowire hybrid layer for memory storage

    NARCIS (Netherlands)

    Cai, R.; Kassa, H.G.; Haouari, R.; Marrani, A.; Geerts, Y.H.; Ruzié, C.; Breemen, A.J.J.M. van; Gelinck, G.H.; Nysten, B.; Hu, Z.; Jonas, A.M.

    2016-01-01

    Ferroelectric materials are important components of sensors, actuators and non-volatile memories. However, possible device configurations are limited due to the need to provide screening charges to ferroelectric interfaces to avoid depolarization. Here we show that, by alternating ferroelectric and

  13. Qualidade tecnológica de grãos e farinhas de trigo nacionais e importados Technological quality of national and imported wheat grain and wheat flours

    Directory of Open Access Journals (Sweden)

    Maria das Graças da Costa

    2008-03-01

    Full Text Available A farinha de trigo possui variadas aplicações na indústria de alimentos, apresentando um importante papel no aspecto econômico e nutricional da alimentação humana. Sabe-se, que as características nutricionais e tecnológicas da farinha de trigo sofrem interferência direta das condições de cultivo, colheita, secagem e armazenamento dos grãos de trigo utilizados como matéria-prima. Este estudo objetivou avasliar a qualidade tecnológica de amostras de grãos de trigo nacionais e importados, bem como de amostras de farinhas produzidas a partir destes grãos, através da análise de parâmetros físico-químicos (umidade, cinzas, glúten úmido, número de quedas e peso hectolitro e da farinografia (absorção de água, tempo de desenvolvimento e estabilidade. As análises físico-químicas mostraram diferenças significativas (p Wheat flour has a wide range of applications in the food industry, with an important economic and nutritional role in the human diet. It is known that the nutritional and technological aspects of wheat flour depend on the cultivation, harvesting, drying and storage conditions of the wheat grains used as raw material. This research aimed at analyzing the technological quality of samples of national and imported wheat grains, as well as of flour samples obtained from them. For this, physical-chemical (moisture, wet gluten, mineral content, falling number, hectoliter weight and farinographic (water absorption, development time, stability analyses were carried out. Physical-chemical analyses showed significant differences (p < 0.05 in the mineral content, wet gluten and falling number of the imported and national grain samples, and also among the flour samples obtained from them. Moisture was the only physical-chemical parameter that did not present a significant difference (p < 0.05 among the national and imported samples. Imported wheat grains and their flours presented higher values for wet gluten (28

  14. Integrated Use of Tools and Technologies for Rapidly Prototyping Simulated Data Products of Future NASA Observing Systems For Evaluation in Applications of National Importance

    Science.gov (United States)

    O'Hara, C. G.; Moorhead, R.; Shaw, D.; Shrestha, B.; Ross, K.; Prados, D.; Russell, J.; Ryan, R. E.

    2006-12-01

    NASA sponsored "Rapid Prototyping Capability" (RPC) research activities of the Mississippi Research Consortium are aimed at developing infrastructure and experiments to evaluate data products from future NASA observing systems in applications, models or decision support tools of national importance. The RPC will host a wide variety of experiments, many of which will require the simulation of data streams to approximate products from future NASA observing systems. To simulate data from a future observing system, a variety of tools and technologies must be employed in an integrated computational workflow. Future data product simulations will typically involve using data products from currently operational science data mission observing systems to provide inputs to a process wherein data will be extracted and manipulated to provide products that approximate the spectral, spatial, radiometric, and temporal characteristics of planned future sensors. The integration of tools and technologies and adapting interfaces for ease of use will enable researchers to test a variety of simulations to efficiently determine an acceptable set of procedures whereby a simulated data product may be derived from existing data sources. Interactive research and testing of data product simulation scenarios will strongly leverage NASA tools and technologies such as the HDF Extraction to GeoTiff tool (HEG2.7) to extract large volumes of data in batch mode, the Time-Series Product Toolkit (TSPT) to evaluate methods for data fusion, de-noising, and creating multi-temporal composites, and the Application Research Toolbox (ART) to manipulate data product characteristics in the simulation process. Given an accepted simulation configuration generated by a set of methods and a documented process workflow, the process will be computationally implemented using Mississippi State University's Temporal Map Algebra (TMA) tools which will enable handling large data sets, computing efficiently the desired

  15. Technology

    Directory of Open Access Journals (Sweden)

    Xu Jing

    2016-01-01

    Full Text Available The traditional answer card reading method using OMR (Optical Mark Reader, most commonly, OMR special card special use, less versatile, high cost, aiming at the existing problems proposed a method based on pattern recognition of the answer card identification method. Using the method based on Line Segment Detector to detect the tilt of the image, the existence of tilt image rotation correction, and eventually achieve positioning and detection of answers to the answer sheet .Pattern recognition technology for automatic reading, high accuracy, detect faster

  16. Nanoimprint-Induced Molecular Orientation in Semiconducting Polymer Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hlaing, H.; Ocko, B.; Lu, X.; Hofmann, T.; Yager, K.G.; Black, C.T.

    2011-09-01

    The morphology and orientation of thin films of the polymer poly-3(hexylthiophene) - important parameters influencing electronic and photovoltaic device performance - have been significantly altered through nanoimprinting with 100 nm spaced grooves. Grazing-incidence small-angle X-ray scattering studies demonstrate the excellent fidelity of the pattern transfer, while wide-angle scattering convincingly shows an imprinting-induced {pi}-{pi} reorientation and polymer backbone alignment along the imprinted grooves. Surprisingly, temperature-dependent scattering measurements indicate that the imprinted induced orientation and alignment remain intact even at temperatures where the imprinted topographical features nearly vanish.

  17. Electronic Transport Properties of (7,0) Semiconducting Carbon Nanotube

    Institute of Scientific and Technical Information of China (English)

    SONG Jiu-Xu; YANG Yin-Wang; CHAI Chang-Chun; LIU Hong-Xia; DING Rui-Xue

    2008-01-01

    Electronic transport properties of a finite (7,0) carbon nanotube (CNT) coupled to Au (111) surfaces are investigated with a fully nonequilibrium Green's functions method combined with the density functional theory. The results show that the coupling effect between the CNT and Au electrode plays an important role in the transport properties, which leads to the formation of a high plateau in the transmission spectrum around Fermi energy. In addition, the current-voltage characteristic of the (7,0) CNT coupled to Au electrodes is different from an isolated (7,0) CNT.

  18. SERS of semiconducting nanoparticles (TIO{sub 2} hybrid composites).

    Energy Technology Data Exchange (ETDEWEB)

    Rajh, T.; Musumeci, A.; Gosztola, D.; Schiller, T.; Dimitrijevic, N. M.; Mujica, V.; Martin, D.; Center for Nanoscale Materials

    2009-05-06

    Raman scattering of molecules adsorbed on the surface of TiO{sub 2} nanoparticles was investigated. We find strong enhancement of Raman scattering in hybrid composites that exhibit charge transfer absorption with TiO{sub 2} nanoparticles. An enhancement factor up to {approx}10{sup 3} was observed in the solutions containing TiO{sub 2} nanoparticles and biomolecules, including the important class of neurotransmitters such as dopamine and dopac (3,4-dihydroxy-phenylacetic acid). Only selected vibrations are enhanced, indicating molecular specificity due to distinct binding and orientation of the biomolecules coupled to the TiO{sub 2} surface. All enhanced modes are associated with the asymmetric vibrations of attached molecules that lower the symmetry of the charge transfer complex. The intensity and the energy of selected vibrations are dependent on the size and shape of nanoparticle support. Moreover, we show that localization of the charge in quantized nanoparticles (2 nm), demonstrated as the blue shift of particle absorption, diminishes SERS enhancement. Importantly, the smallest concentration of adsorbed molecules shows the largest Raman enhancements suggesting the possibility for high sensitivity of this system in the detection of biomolecules that form a charge transfer complex with metal oxide nanoparticles. The wavelength-dependent properties of a hybrid composite suggest a Raman resonant state. Adsorbed molecules that do not show a charge transfer complex show weak enhancements probably due to the dielectric cavity effect.

  19. Voltage-gated ion transport through semiconducting conical nanopores formed by metal nanoparticle-assisted plasma etching.

    Science.gov (United States)

    James, Teena; Kalinin, Yevgeniy V; Chan, Chih-Chieh; Randhawa, Jatinder S; Gaevski, Mikhail; Gracias, David H

    2012-07-11

    Nanopores with conical geometries have been found to rectify ionic current in electrolytes. While nanopores in semiconducting membranes are known to modulate ionic transport through gated modification of pore surface charge, the fabrication of conical nanopores in silicon (Si) has proven challenging. Here, we report the discovery that gold (Au) nanoparticle (NP)-assisted plasma etching results in the formation of conical etch profiles in Si. These conical profiles result due to enhanced Si etch rates in the vicinity of the Au NPs. We show that this process provides a convenient and versatile means to fabricate conical nanopores in Si membranes and crystals with variable pore-diameters and cone-angles. We investigated ionic transport through these pores and observed that rectification ratios could be enhanced by a factor of over 100 by voltage gating alone, and that these pores could function as ionic switches with high on-off ratios of approximately 260. Further, we demonstrate voltage gated control over protein transport, which is of importance in lab-on-a-chip devices and biomolecular separations.

  20. Multimodal probing of oxygen and water interaction with metallic and semiconducting carbon nanotube networks under ultraviolet irradiation

    Science.gov (United States)

    Muckley, Eric S.; Nelson, Anthony J.; Jacobs, Christopher B.; Ivanov, Ilia N.

    2016-04-01

    Interaction between ultraviolet (UV) light and carbon nanotube (CNT) networks plays a central role in gas adsorption, sensor sensitivity, and stability of CNT-based electronic devices. To determine the effect of UV light on sorption kinetics and resistive gas/vapor response of different CNT networks, films of semiconducting single-wall nanotubes (s-SWNTs), metallic single-wall nanotubes, and multiwall nanotubes were exposed to O2 and H2O vapor in the dark and under UV irradiation. Changes in film resistance and mass were measured in situ. In the dark, resistance of metallic nanotube networks increases in the presence of O2 and H2O, whereas resistance of s-SWNT networks decreases. UV irradiation decreases the resistance of metallic nanotube networks in the presence of O2 and H2O and increases the gas/vapor sensitivity of s-SWNT networks by nearly a factor of 2 compared to metallic nanotube networks. s-SWNT networks show evidence of delamination from the gold-plated quartz crystal microbalance crystal, possibly due to preferential adsorption of O2 and H2O on gold. UV irradiation increases the sensitivity of all CNT networks to O2 and H2O by an order of magnitude, which demonstrates the importance of UV light for enhancing response and lowering detection limits in CNT-based gas/vapor sensors.

  1. Exploring a Lead-free Semiconducting Hybrid Ferroelectric with a Zero-Dimensional Perovskite-like Structure.

    Science.gov (United States)

    Sun, Zhihua; Zeb, Aurang; Liu, Sijie; Ji, Chengmin; Khan, Tariq; Li, Lina; Hong, Maochun; Luo, Junhua

    2016-09-19

    Perovskite lead halides (CH3 NH3 PbI3 ) have recently taken a promising position in photovoltaics and optoelectronics because of remarkable semiconducting properties and possible ferroelectricity. However, the potential toxicity of lead arouses great environmental concern for widespread application. A new chemically tailored lead-free semiconducting hybrid ferroelectric is reported, N-methylpyrrolidinium)3 Sb2 Br9 (1), which consists of a zero-dimensional (0-D) perovskite-like anionic framework connected by corner- sharing SbBr6 coordinated octahedra. It presents a large ferroelectric spontaneous polarization of approximately 7.6 μC cm(-2) , as well as notable semiconducting properties, including positive temperature-dependent conductivity and ultraviolet-sensitive photoconductivity. Theoretical analysis of electronic structure and energy gap discloses a dominant contribution of the 0-D perovskite-like structure to the semiconducting properties of the material. This finding throws light on the rational design of new perovskite-like hybrids, especially lead-free semiconducting ferroelectrics.

  2. Structural and transport properties of metallic and semiconducting Sb{sub 2}Te{sub 3} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Das, Diptasikha; Malik, K.; Bandyopadhyay, S.; Banerjee, S.; Banerjee, Aritra, E-mail: arbphy@caluniv.ac.in [Department of Physics, University of Calcutta, 92 A P C Road, Kolkata-700009 (India); Dhara, S. [Surface and Nanoscience Division, Indira Gandhi Center for Atomic Research, Kalpakkam-603102 (India)

    2015-06-24

    Metallic and semiconducting Sb{sub 2}Te{sub 3} alloys have been synthesized by controlling the cooling rate in the solid state reaction method. Temperature dependent resistivity is measured down to 10 K for the identification of metallic and semiconducting phases. Structural studies are performed by both X-ray diffraction (XRD) and Raman spectroscopic analyses. XRD study confirms single phase nature of polycrystalline alloys in the detectable limit. Raman spectroscopy is used to understand the vibration properties of Sb{sub 2}Te{sub 3} crystals. Widening of full width at half maxima of the highest intense peak in the XRD analysis indicates higher amount of defects in the semiconducting phase than that in the metallic one. Raman study indicates presence of impurity phases in the semiconducting Sb{sub 2}Te{sub 3}. The resistivity of semiconducting Sb{sub 2}Te{sub 3} sample is higher than that of metallic one, which corroborates with the XRD and Raman analyses.

  3. Investigation of semiconducting YBaCuO thin films: A new room temperature bolometer

    Science.gov (United States)

    Shan, P. C.; ćelik-Butler, Z.; Butler, D. P.; Jahanzeb, A.; Travers, C. M.; Kula, W.; Sobolewski, Roman

    1996-12-01

    We explore the application of the semiconducting phases of YBaCuO thin films as a bolometer for uncooled infrared detection. For this study, four different structures were built with different types of buffer layers: YBaCuO on a Si substrate with and without a MgO buffer layer, and on an oxidized Si substrate with and without a MgO buffer layer. These films were all amorphous without a detectable long range order. For comparison, crystalline tetragonal YBa2Cu3O6.5 and YBa2Cu3O6.3 thin films on a LaAlO3 substrate were included into the study. All six films exhibited semiconducting resistance versus temperature characteristics. The bolometer figures of merit, responsivity, and detectivity were calculated from the measured temperature coefficient of resistance (TCR) and the inherent noise characteristics of the temperature sensing element. The room temperature TCRs for all four amorphous films were greater than 2.5% K-1. The highest TCR of 4.02% K-1 was observed on the amorphous YBaCuO thin film deposited on MgO/Si without a SiO2 layer. The TCR of the tetragonal films, on the other hand, remained 2% K-1 or less in the same temperature range. Noise measurements performed in the 1-100 Hz frequency range revealed a quadratic dependence on the bias current as would be expected from ohmic electrical characteristics. The Johnson and 1/f regions were clearly identified in the noise spectrum. From TCR and noise measurements, we estimated the amorphous semiconducting YBaCuO bolometers would have a responsivity as high as 3.8×105 V/W and a detectivity as high as 1.6×109 cm Hz1/2/W for 1 μA bias current and frame frequency of 30 Hz if integrated with a typical air-gap thermal isolation structure.

  4. Role of Molecular Weight Distribution on Charge Transport in Semiconducting Polymers

    KAUST Repository

    Himmelberger, Scott

    2014-10-28

    © 2014 American Chemical Society. Model semiconducting polymer blends of well-controlled molecular weight distributions are fabricated and demonstrated to be a simple method to control intermolecular disorder without affecting intramolecular order or degree of aggregation. Mobility measurements exhibit that even small amounts of low molecular weight material are detrimental to charge transport. Trends in charge carrier mobility can be reproduced by a simple analytical model which indicates that carriers have no preference for high or low molecular weight chains and that charge transport is limited by interchain hopping. These results quantify the role of long polymer tie-chains and demonstrate the need for controlled polydispersity for achieving high carrier mobilities.

  5. Semiconducting, Magnetic or Superconducting Nanoparticles encapsulated in Carbon Shells by RAPET method.

    Directory of Open Access Journals (Sweden)

    Aharon Gedanken

    2008-06-01

    Full Text Available An efficient, solvent-free, environmentally friendly, RAPET (Reactions under Autogenic Pressure at Elevated Temperaturesynthetic approach is discussed for the fabrication of core-shell nanostructures. The semiconducting, magnetic orsuperconducting nanoparticles are encapsulated in a carbon shell. RAPET is a one-step, thermal decomposition reaction ofchemical compound (s followed by the formation of core-shell nanoparticles in a closed stainless steel reactor. Therepresentative examples are discussed, where a variety of nanomaterials are trapped in situ in a carbon shell that offersfascinating properties.

  6. Photoelectron detection from transient species in organic semiconducting thin films by dual laser pulse irradiation

    Science.gov (United States)

    Hosokai, Takuya; Matsuzaki, Hiroyuki; Furube, Akihiro; Nakamura, Ken

    2017-02-01

    An Nd3+:YAG pulsed laser was employed as a light source for two-photon photoemission from organic semiconducting thin films in low vacuum and air. Photoionization by the two-photon process was confirmed in both the environments by measuring photoemission current. By constructing a pump-probe system, photoemissions from transient species formed by the pump light irradiation were detected by probe light irradiation as a result of a linear increase in the photocurrent with the pump power via a one-photon process. Thus, we propose a novel method called two-photon photoelectron yield spectroscopy to determine the excited-state energy levels in ambient environments.

  7. Experimental study of lattice dynamics in individual semiconducting double-walled carbon nanotubes: Tangential G modes

    Science.gov (United States)

    Levshov, D. I.; Tran, H. N.; Slabodyan, Yu. S.; Osadchii, A. V.; Roshal', S. B.; Yuzyuk, Yu. I.

    2017-02-01

    The tangential G modes in individual semiconducting double-walled nanotubes have been examined via Raman spectroscopy over a wide laser excitation wavelength range. Individual suspended nanotubes have been synthesized via chemical vapor deposition. The ( n, m) chirality indices are determined via electron diffraction and high-resolution transmission electron microscopy. The pronounced shift in the tangential modes compared to the analogous modes of single-walled nanotubes has been observed in Raman spectra of double-walled nanotubes. The shift value is shown to depend on the interlayer distance and on the van der Waals interaction between the layers in a double-walled tube.

  8. Thermal Vibration and Twist Induced Semiconducting Behaviour in Short DNA Wires

    Institute of Scientific and Technical Information of China (English)

    WU Zheng-Yi; FENG Jin-Fu; WU Xiao-Shan

    2009-01-01

    We study the transport properties of electrons in a short homogeneous DNA molecule where thermal vibrations and twist fluctuations of the base molecules are considered. The nonlinear current-voltage curves can be derived by using the equivalent single-particle multichannel network. The voltage gap is sensitive to the strength of thermal vibrations and twist fluctuations of the base molecules. Our results are in good agreement with the recent finding of semiconducting behaviour in short poly(G)-poly(C) DNA oligomers. The present method can also be used to calculate the other molecular wires.

  9. Semiconducting behavior of the anodically passive films formed on AZ31B alloy

    OpenAIRE

    A. Fattah-alhosseini; M. Sabaghi Joni

    2014-01-01

    This work includes determination of the semiconductor character and estimation of the dopant levels in the passive film formed on AZ31B alloy in 0.01 M NaOH, as well as the estimation of the passive film thickness as a function of the film formation potential. Mott–Schottky analysis revealed that the passive films displayed n-type semiconductive characteristics, where the oxygen vacancies and interstitials preponderated. Based on the Mott–Schottky analysis, it was shown that the calculated do...

  10. Deterministic radiative coupling between plasmonic nanoantennas and semiconducting nanowire quantum dots

    CERN Document Server

    Jeannin, Mathieu; Bellet-Amalric, Edith; Kheng, Kuntheak; Nogues, Gilles

    2016-01-01

    We report on the deterministic coupling between single semiconducting nanowire quantum dots emitting in the visible and plasmonic Au nanoantennas. Both systems are separately carefully characterized through microphotoluminescence and cathodoluminescence. A two-step realignment process using cathodoluminescence allows for electron beam lithography of Au antennas near individual nanowire quantum dots with a precision of 50 nm. A complete set of optical properties are measured before and after antenna fabrication. They evidence both an increase of the NW absorption, and an improvement of the quantum dot emission rate up to a factor two in presence of the antenna.

  11. Bioengineered Silicon Diatoms: Adding Photonic Features to a Nanostructured Semiconductive Material for Biomolecular Sensing

    Science.gov (United States)

    Rea, Ilaria; Terracciano, Monica; Chandrasekaran, Soundarrajan; Voelcker, Nicolas H.; Dardano, Principia; Martucci, Nicola M.; Lamberti, Annalisa; De Stefano, Luca

    2016-09-01

    Native diatoms made of amorphous silica are first converted into silicon structures via magnesiothermic process, preserving the original shape: electron force microscopy analysis performed on silicon-converted diatoms demonstrates their semiconductor behavior. Wet surface chemical treatments are then performed in order to enhance the photoluminescence emission from the resulting silicon diatoms and, at the same time, to allow the immobilization of biological probes, namely proteins and antibodies, via silanization. We demonstrate that light emission from semiconductive silicon diatoms can be used for antibody-antigen recognition, endorsing this material as optoelectronic transducer.

  12. Electrical and structural properties of the YBCO superconducting-semiconducting interface

    Energy Technology Data Exchange (ETDEWEB)

    Sobolewski, R. (Dept. of Electrical Engineering and Lab. for Laser Energetics, Univ. of Rochester, NY (United States) Inst. of Physics, Polish Academy of Sciences, Warszawa (Poland)); Xiong, W. (Dept. of Electrical Engineering and Lab. for Laser Energetics, Univ. of Rochester, NY (United States)); Kula, W. (Dept. of Electrical Engineering and Lab. for Laser Energetics, Univ. of Rochester, NY (United States) Inst. of Physics, Polish Academy of Sciences, Warszawa (Poland)); McIntyre, B. (Inst. of Optics, Univ. of Rochester, NY (United States))

    1994-02-01

    We report our studies on electrical and structural properties of an interface between the oxygen-poor (semiconducting) and oxygen-rich (superconducting, T[sub c] = 89.5 K) YBa[sub 2]Cu[sub 3]O[sub y]. Our thin-film test structures were fully monolithic and prepared by a laser-writing patterning technique. Scanning electron and optical microscopy measurements revealed that the interface was very sharp (<1 [mu]m wide) and did not smear over the period of several months. Electrical measurements of the interface showed completely linear current-voltage characteristics in the tested temperature range between 77 and 300 K. (orig.)

  13. Biotin-Functionalized Semiconducting Polymer in an Organic Field Effect Transistor and Application as a Biosensor

    OpenAIRE

    Yong Suk Yang; Do-Hoon Hwang; Seong Hyun Kim; Sang Chul Lim; Zin-Sig Kim

    2012-01-01

    This report presents biotin-functionalized semiconducting polymers that are based on fluorene and bithiophene co-polymers (F8T2). Also presented is the application of these polymers to an organic thin film transistor used as a biosensor. The side chains of fluorene were partially biotinylated after the esterification of the biotin with corresponding alcohol-groups at the side chain in F8T2. Their properties as an organic semiconductor were tested using an organic thin film transistor (OTFT) a...

  14. Influence of cysteine doping on photoluminescence intensity from semiconducting single-walled carbon nanotubes

    Science.gov (United States)

    Kurnosov, N. V.; Leontiev, V. S.; Linnik, A. S.; Karachevtsev, V. A.

    2015-03-01

    Photoluminescence (PL) from semiconducting single-walled carbon nanotubes can be applied for detection of cysteine. It is shown that cysteine doping (from 10-8 to 10-3 M) into aqueous suspension of nanotubes with adsorbed DNA leads to increase of PL intensity. The PL intensity was enhanced by 27% at 10-3 M cysteine concentration in suspension. Most likely, the PL intensity increases due to the passivation of p-defects on the nanotube by the cysteine containing reactive thiol group. The effect of doping with other amino acids without this group (methionine, serine, aspartic acid, lysine, proline) on the PL intensity is essentially weaker.

  15. 我国重点企业技术创新现状与问题研究%The Analysis of Technological Innovation Situation of Important Enterprises of China and the Related Problems

    Institute of Scientific and Technical Information of China (English)

    李文海

    2004-01-01

    The paper analyses in detail the current technological innovation situation and existing problems of important enterprises of China and further brings forward some policy suggestions to solve the problems.

  16. Evaluation of polarization rotation in the scattering responses from individual semiconducting oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Daniel S.; Singh, Manpreet; Zhou, Hebing; Milchak, Marissa; Monahan, Brian; Hahm, Jong-in, E-mail: jh583@georgetown.edu [Department of Chemistry, Georgetown University, 37" t" h & O Sts. NW., Washington, DC 20057 (United States)

    2016-04-15

    We investigate the interaction of visible light with the solid matters of semiconducting oxide nanorods (NRs) of zinc oxide (ZnO), indium tin oxide (ITO), and zinc tin oxide (ZTO) at the single nanomaterial level. We subsequently identify an intriguing, material-dependent phenomenon of optical rotation in the electric field oscillation direction of the scattered light by systematically controlling the wavelength and polarization direction of the incident light, the NR tilt angle, and the analyzer angle. This polarization rotation effect in the scattered light is repeatedly observed from the chemically pure and highly crystalline ZnO NRs, but absent on the chemically doped NR variants of ITO and ZTO under all measurement circumstances. We further elucidate that the phenomenon of polarization rotation detected from single ZnO NRs is affected by the NR tilt angle, while the phenomenon itself occurs irrespective of the wavelength and incident polarization direction of the visible light. Combined with the widespread optical and optoelectronic use of the semiconducting oxide nanomaterials, these efforts may provide much warranted fundamental bases to tailor material-specific, single nanomaterial-driven, optically modulating functionalities which, in turn, can be beneficial for the realization of high-performance integrated photonic circuits and miniaturized bio-optical sensing devices.

  17. Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes

    Science.gov (United States)

    Blancon, Jean-Christophe; Paillet, Matthieu; Tran, Huy Nam; Than, Xuan Tinh; Guebrou, Samuel Aberra; Ayari, Anthony; Miguel, Alfonso San; Phan, Ngoc-Minh; Zahab, Ahmed-Azmi; Sauvajol, Jean-Louis; Fatti, Natalia Del; Vallée, Fabrice

    2013-09-01

    The optical properties of single-wall carbon nanotubes are very promising for developing novel opto-electronic components and sensors with applications in many fields. Despite numerous studies performed using photoluminescence or Raman and Rayleigh scattering, knowledge of their optical response is still partial. Here we determine using spatial modulation spectroscopy, over a broad optical spectral range, the spectrum and amplitude of the absorption cross-section of individual semiconducting single-wall carbon nanotubes. These quantitative measurements permit determination of the oscillator strength of the different excitonic resonances and their dependencies on the excitonic transition and type of semiconducting nanotube. A non-resonant background is also identified and its cross-section comparable to the ideal graphene optical absorbance. Furthermore, investigation of the same single-wall nanotube either free standing or lying on a substrate shows large broadening of the excitonic resonances with increase of oscillator strength, as well as stark weakening of polarization-dependent antenna effects, due to nanotube-substrate interaction.

  18. 5,10-linked naphthodithiophenes as the building block for semiconducting polymers

    Science.gov (United States)

    Osaka, Itaru; Komatsu, Koki; Koganezawa, Tomoyuki; Takimiya, Kazuo

    2014-04-01

    We present new semiconducting polymers incorporating naphtho[1, 2-b:5, 6-b‧] dithiophene (NDT3) and naphtho[2, 1-b:6, 5-b‧] dithiophene (NDT4), which are linked at the naphthalene positions, in the polymer backbone. It is interesting that the trend in the ordering structure and thus charge transport properties are quite different from what were observed in the isomeric polymers where the NDT3 and NDT4 cores are linked at the thiophene α-positions. In the thiophene-linked NDT system, the NDT3-based polymer (PNDT3BT) gave the better ordering in thin films and thus the high charge carrier mobility compared to the NDT4-based polymer (PNDT4BT). In the meantime, in the naphthalene-linked NDT system, the NDT4-based polymer (PNDT4iBT) provided the superior properties. Considering that PNDT4iBT has relatively low highest occupied molecular orbital (HOMO) energy level (-5.2 eV) and moderately high mobilities in the order of 10-2 cm2 V-1 s-1, the NDT4 core, when linked at the naphthalene positions, can be a good building unit for the development of high-performance semiconducting polymers for both organic field-effect transistors and photovoltaic devices.

  19. Optimization of thermoelectric performance in semiconducting polymers for understanding charge transport and flexible thermoelectric applications

    Science.gov (United States)

    Glaudell, Anne; Chabinyc, Michael

    2014-03-01

    Organic electronic materials have been widely considered for a variety of energy conversion applications, from photovoltaics to LEDs. Only very recently have organic materials been considered for thermoelectric applications - converting between temperature gradients and electrical potential. The intrinsic disorder in semiconducting polymers leads to an inherently low thermal conductivity, a key parameter in thermoelectric performance. The ability to solution deposit on flexible substrates opens up niche applications including personal cooling and conformal devices. Here work is presented on the electrical conductivity and thermopower of thin film semiconducting polymers, including P3HT and PBTTT-C14. Thermoelectric properties are explored over a wide range of conductivities, from nearly insulating to beyond 100 S/cm, enabled by employing different doping mechanisms, including molecular charge-transfer doping with F4TCNQ and vapor doping with a fluoroalkyl trichlorosilane (FTS). Temperature-dependent measurements suggest competing charge transport mechanisms, likely due to the mixed ordered/disordered character of these polymers. These results show promise for organic materials for thermoelectric applications, and recent results on thin film devices will also be presented.

  20. Evaluation of polarization rotation in the scattering responses from individual semiconducting oxide nanorods

    Science.gov (United States)

    Choi, Daniel S.; Singh, Manpreet; Zhou, Hebing; Milchak, Marissa; Monahan, Brian; Hahm, Jong-in

    2016-01-01

    We investigate the interaction of visible light with the solid matters of semiconducting oxide nanorods (NRs) of zinc oxide (ZnO), indium tin oxide (ITO), and zinc tin oxide (ZTO) at the single nanomaterial level. We subsequently identify an intriguing, material-dependent phenomenon of optical rotation in the electric field oscillation direction of the scattered light by systematically controlling the wavelength and polarization direction of the incident light, the NR tilt angle, and the analyzer angle. This polarization rotation effect in the scattered light is repeatedly observed from the chemically pure and highly crystalline ZnO NRs, but absent on the chemically doped NR variants of ITO and ZTO under all measurement circumstances. We further elucidate that the phenomenon of polarization rotation detected from single ZnO NRs is affected by the NR tilt angle, while the phenomenon itself occurs irrespective of the wavelength and incident polarization direction of the visible light. Combined with the widespread optical and optoelectronic use of the semiconducting oxide nanomaterials, these efforts may provide much warranted fundamental bases to tailor material-specific, single nanomaterial-driven, optically modulating functionalities which, in turn, can be beneficial for the realization of high-performance integrated photonic circuits and miniaturized bio-optical sensing devices. PMID:27158560

  1. A Semi-Conductive Copper-Organic Framework with Two Types of Photocatalytic Activity.

    Science.gov (United States)

    Wu, Zhi-Lei; Wang, Chang-Hong; Zhao, Bin; Dong, Jie; Lu, Feng; Wang, Wei-Hua; Wang, Wei-Chao; Wu, Guang-Jun; Cui, Jian-Zhong; Cheng, Peng

    2016-04-11

    Based on the newly designed ligand 4'-(3,5-dicarboxyphenyl)-4,2':6',4''-terpyridine (DCTP), a unique semi-conductive 3D framework {[Cu(Ι)Cu(ΙΙ)2(DCTP)2]NO3⋅1.5 DMF}n (1) with a narrow band gap of 2.1 eV, was obtained and structurally characterized. DFT calculations with van de Waals correction employed to explore the electronic structure of 1, clearly revealed its semi-conductive behavior. Furthermore, we found that 1 exhibits a superior band alignment with water to produce hydrogen and degrade organic pollutants. Without adding any photosensitizers, 1 displays an efficiently photocatalytic hydrogen production in water based on the photo-generated electrons under UV/Vis light. 1 also exhibits excellent photo-degradation of methyl blue under visible-light owing to the strong oxidization of excited holes. It is the first example of MOFs with doubly photocatalytic activities related to photo-generated electrons and holes, respectively.

  2. Challenges Found When Patterning Semiconducting Polymers with Electric Fields for Organic Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Fernando A. de Castro

    2012-01-01

    Full Text Available A material-independent, contactless structuring method of semiconducting organic materials for the fabrication of interface-enhanced bilayer solar cells is not available so far. Patterning of thin films using electrohydrodynamic instabilities possesses many desired characteristics and has convincingly been used as a simple method to structure and replicate patterns of nonconducting polymers on submicrometer length scales. However, the applicability of this technique to a wider range of materials has not been demonstrated yet. Here, we report attempts to structure poly(p-phenylene vinylene in a similar way. We found that thin films of poly(2-methoxy-5-(2′-ethylhexyl-oxy-1,4-phenylene-vinylene (MEH-PPV and poly(2-methoxy-5-(3′,7′-dimethyloctyloxy-1,4-phenylene-vinylene (MDMO-PPV could not be destabilized at all in the limited accessible range of the experimental parameters set by the delicate chemical nature of these materials. We discuss failure origins and present possible loopholes for the patterning of semiconducting polymers using electric fields.

  3. Enhancement in semiconducting and optical properties in doped anthracene micro crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Nidhi [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India); Department of Electronics, SGTB Khalsa College, University of Delhi, Delhi-7 (India); Ray, Geeta; Godara, Sanjay; Yadav, Harsh; Bhandari, Sonia [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India); Kumar, Binay, E-mail: b3kumar69@yahoo.co.in [Crystal Lab, Department of Physics & Astrophysics, University of Delhi, Delhi-7 (India)

    2015-08-15

    Effect of CuCl{sub 2} doping on structural, optical, dielectric and semiconducting behavior of solution grown anthracene crystals has been reported. UV–vis spectra showed a blue shift of various peaks in the range of 350–390 nm. A broad peak around 760 nm of high intensity appeared in Cu{sup 2+} doped anthracene. Remarkable increase in dielectric constant and ac conductivity were observed along with a structure related phase transition at 126 °C. Different mechanisms of ac conductivity for the two temperature ranges, typically below and above 60 °C, were reported. A higher dependence of conductivity on temperature above 60 °C established enhanced semiconducting behavior in doped crystals. Change in activation energy has been reported in different temperature regions. In photoluminescence (PL) studies, three strong blue/UV emissions were obtained at 400 nm, 424 nm and 450 nm in both the crystals and a remarkable PL quenching has been observed in the doped anthracene.

  4. Scintillation properties of semiconducting {sup 6}LiInSe{sub 2} crystals to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Wiggins, Brenden [Y-12 National Security Complex, Oak Ridge, TN (United States); Vanderbilt University, Nashville, TN (United States); Groza, Michael; Tupitsyn, Eugene [Fisk University, Nashville, TN (United States); Lukosi, Eric [University of Tennessee, Knoxville, TN (United States); Stassun, Keivan; Burger, Arnold [Vanderbilt University, Nashville, TN (United States); Fisk University, Nashville, TN (United States); Stowe, Ashley [Y-12 National Security Complex, Oak Ridge, TN (United States); Vanderbilt University, Nashville, TN (United States); University of Tennessee, Knoxville, TN (United States)

    2015-11-21

    {sup 6}LiInSe{sub 2} has gained attention recently as a semiconducting thermal neutron detector. As presented herein, the chalcogenide compound semiconductor also detects incident neutrons via scintillation, making {sup 6}LiInSe{sub 2} the only lithium containing semiconductor to respond to neutrons via both detection mechanisms. Both yellow and red crystals, which appear in the literature, were investigated. Only the yellow crystal responded favorably to ionizing radiation, similar to the semiconducting operation utilizing electrodes. The obtained light yield for yellow crystals is 4400 photons/MeV, referenced to Bi{sub 4}Ge{sub 3}O{sub 12} (BGO).The estimated thermal neutron light yield was 21,000 photons/thermal neutron. The two measured decay time components were found to be 31±1 ns (49%) and 143±9 ns (51%).This crystal provides efficient, robust detection of neutrons via scintillation with respectable light yield and rapid response, enabling its use for a broad array of neutron detection applications.

  5. New anthracene-based-phtalocyanine semi-conducting materials: Synthesis and optoelectronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Kahouech, M.S. [Laboratoire de Chimie Organique et Analytique, Institut Supérieur de l' Education et de la Formation Continue (Université El Manar), Bardo 2000 (Tunisia); Hriz, K., E-mail: khaledhriz@gmail.com [Laboratoire des Interfaces et Matériaux Avancés (LIMA), Faculté des Sciences de Monastir (Université de Monastir), Bd. de l' Environnement, Monastir 5019 (Tunisia); Touaiti, S.; Bassem, J. [Laboratoire de Chimie Organique et Analytique, Institut Supérieur de l' Education et de la Formation Continue (Université El Manar), Bardo 2000 (Tunisia)

    2016-03-15

    Highlights: • Synthesis of tow phtalocyanines based on the anthracene and tetrazole. • Semi-conducting supramolecular material. • Good PL quantum yield. • The film morphology of the phtalocynine containing tetrazole group enhanced the carrier mobility. - Abstract: A new anthracene-based semi-conducting phtalocyanines AnPc and AnPc-Tr were synthesized in solvent-free conditions. The supramolecular structure of these compounds was confirmed by NMR and FT-IR spectroscopies. Their optical properties were investigated by UV–vis and photoluminescence spectroscopies. The optical gaps were estimated from the absorption-onsets films, and the obtained values were of 1.50 eV and 1.47 eV for AnPc-Tr and AnPc respectively. In solid state, a weaker π–π-interactions of conjugated systems were obtained in the case of AnPc-Tr in comparison with AnPc. This behavior was explained by steric hindrance of triazol groups, which decrease the planarity of macromolecular structure. The HOMO and LUMO levels were estimated using cyclic voltammetry analysis; two phtalocyanine derivatives show a comparable ionization potential. The phtalacyanine containing triazole groups (AnPc-Tr) reveals a higher electron affinity in comparison with AnPc. Single-layer diode devices were fabricated and showed relatively low turn-on voltages.

  6. 5,10-linked naphthodithiophenes as the building block for semiconducting polymers

    Directory of Open Access Journals (Sweden)

    Itaru Osaka

    2014-04-01

    Full Text Available We present new semiconducting polymers incorporating naphtho[1, 2-b:5, 6-b'] dithiophene (NDT3 and naphtho[2, 1-b:6, 5-b'] dithiophene (NDT4, which are linked at the naphthalene positions, in the polymer backbone. It is interesting that the trend in the ordering structure and thus charge transport properties are quite different from what were observed in the isomeric polymers where the NDT3 and NDT4 cores are linked at the thiophene α-positions. In the thiophene-linked NDT system, the NDT3-based polymer (PNDT3BT gave the better ordering in thin films and thus the high charge carrier mobility compared to the NDT4-based polymer (PNDT4BT. In the meantime, in the naphthalene-linked NDT system, the NDT4-based polymer (PNDT4iBT provided the superior properties. Considering that PNDT4iBT has relatively low highest occupied molecular orbital (HOMO energy level (−5.2 eV and moderately high mobilities in the order of 10−2 cm2 V−1 s−1, the NDT4 core, when linked at the naphthalene positions, can be a good building unit for the development of high-performance semiconducting polymers for both organic field-effect transistors and photovoltaic devices.

  7. Half-cell potentials of semiconductive simple binary sulphides in aqueous solution

    Science.gov (United States)

    Sato, M.

    1966-01-01

    Theoretical consideration of the charge-transfer mechanism operative in cells with an electrode of a semiconductive binary compound leads to the conclusion that the half-cell potential of such a compound is not only a function of ionic activities in the electrolytic solution, but also a function of the activities of the component elements in the compound phase. The most general form of the electrode equation derived for such a compound with a formula MiXj which dissociates into Mj+ and Xi- ions in aqueous solution is. EMiXj = EMiXj0 + R T 2 ij ln [ (sua Mj+)aqi ?? (suaX)jMiXj/ (suaXi-)aqj ?? (suaM)iMiXj],. where. EMiXj0 = 1 2(EM,Mj+0 + EXi-,X). The equation can be modified to other forms. When applied to semiconductive simple binary sulphides, these equations appear to give better descriptions of the observed electrode potentials of such sulphides than any other proposed equations. ?? 1966.

  8. Tunable Semiconducting Polymer Nanoparticles with INDT-Based Conjugated Polymers for Photoacoustic Molecular Imaging.

    Science.gov (United States)

    Stahl, Thomas; Bofinger, Robin; Lam, Ivan; Fallon, Kealan J; Johnson, Peter; Ogunlade, Olumide; Vassileva, Vessela; Pedley, R Barbara; Beard, Paul C; Hailes, Helen C; Bronstein, Hugo; Tabor, Alethea B

    2017-06-21

    Photoacoustic imaging combines both excellent spatial resolution with high contrast and specificity, without the need for patients to be exposed to ionizing radiation. This makes it ideal for the study of physiological changes occurring during tumorigenesis and cardiovascular disease. In order to fully exploit the potential of this technique, new exogenous contrast agents with strong absorbance in the near-infrared range, good stability and biocompatibility, are required. In this paper, we report the formulation and characterization of a novel series of endogenous contrast agents for photoacoustic imaging in vivo. These contrast agents are based on a recently reported series of indigoid π-conjugated organic semiconductors, coformulated with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, to give semiconducting polymer nanoparticles of about 150 nm diameter. These nanoparticles exhibited excellent absorption in the near-infrared region, with good photoacoustic signal generation efficiencies, high photostability, and extinction coefficients of up to three times higher than those previously reported. The absorption maximum is conveniently located in the spectral region of low absorption of chromophores within human tissue. Using the most promising semiconducting polymer nanoparticle, we have demonstrated wavelength-dependent differential contrast between vasculature and the nanoparticles, which can be used to unambiguously discriminate the presence of the contrast agent in vivo.

  9. Regulating Near-Infrared Photodynamic Properties of Semiconducting Polymer Nanotheranostics for Optimized Cancer Therapy.

    Science.gov (United States)

    Zhu, Houjuan; Fang, Yuan; Miao, Qingqing; Qi, Xiaoying; Ding, Dan; Chen, Peng; Pu, Kanyi

    2017-09-26

    Development of optical nanotheranostics for the capability of photodynamic therapy (PDT) provides opportunities for advanced cancer therapy. However, most nanotheranostic systems fail to regulate their generation levels of reactive oxygen species (ROS) according to the disease microenvironment, which can potentially limit their therapeutic selectivity and increase the risk of damage to normal tissues. We herein report the development of hybrid semiconducting polymer nanoparticles (SPNs) with self-regulated near-infrared (NIR) photodynamic properties for optimized cancer therapy. The SPNs comprise a binary component nanostructure: a NIR-absorbing semiconducting polymer acts as the NIR fluorescent PDT agent, while nanoceria serves as the smart intraparticle regular to decrease and increase ROS generation at physiologically neutral and pathologically acidic environments, respectively. As compared with nondoped SPNs, the NIR fluorescence imaging ability of nanoceria-doped SPNs is similar due to the optically inactive nature of nanoceria; however, the self-regulated photodynamic properties of nanoceria-doped SPN not only result in dramatically reduced nonspecific damage to normal tissue under NIR laser irradiation but also lead to significantly enhanced photodynamic efficacy for cancer therapy in a murine mouse model. This study thus provides a simple yet effective hybrid approach to modulate the phototherapeutic performance of organic photosensitizers.

  10. Antibody VH and VL recombination using phage and ribosome display technologies reveals distinct structural routes to affinity improvements with VH-VL interface residues providing important structural diversity.

    Science.gov (United States)

    Groves, Maria A T; Amanuel, Lily; Campbell, Jamie I; Rees, D Gareth; Sridharan, Sudharsan; Finch, Donna K; Lowe, David C; Vaughan, Tristan J

    2014-01-01

    In vitro selection technologies are an important means of affinity maturing antibodies to generate the optimal therapeutic profile for a particular disease target. Here, we describe the isolation of a parent antibody, KENB061 using phage display and solution phase selections with soluble biotinylated human IL-1R1. KENB061 was affinity matured using phage display and targeted mutagenesis of VH and VL CDR3 using NNS randomization. Affinity matured VHCDR3 and VLCDR3 library blocks were recombined and selected using phage and ribosome display protocol. A direct comparison of the phage and ribosome display antibodies generated was made to determine their functional characteristics.In our analyses, we observed distinct differences in the pattern of beneficial mutations in antibodies derived from phage and ribosome display selections, and discovered the lead antibody Jedi067 had a ~3700-fold improvement in KD over the parent KENB061. We constructed a homology model of the Fv region of Jedi067 to map the specific positions where mutations occurred in the CDR3 loops. For VL CDR3, positions 94 to 97 carry greater diversity in the ribosome display variants compared with the phage display. The positions 95a, 95b and 96 of VLCDR3 form part of the interface with VH in this model. The model shows that positions 96, 98, 100e, 100f, 100 g, 100h, 100i and 101 of the VHCDR3 include residues at the VH and VL interface. Importantly, Leu96 and Tyr98 are conserved at the interface positions in both phage and ribosome display indicating their importance in maintaining the VH-VL interface. For antibodies derived from ribosome display, there is significant diversity at residues 100a to 100f of the VH CDR3 compared with phage display. A unique deletion of isoleucine at position 102 of the lead candidate, Jedi067, also occurs in the VHCDR3.As anticipated, recombining the mutations via ribosome display led to a greater structural diversity, particularly in the heavy chain CDR3, which in turn

  11. Thin film thermistor with positive temperature coefficient of resistance based on phase separated blends of ferroelectric and semiconducting polymers

    Science.gov (United States)

    Lenz, Thomas; Sharifi Dehsari, Hamed; Asadi, Kamal; Blom, Paul W. M.; Groen, Wilhelm A.; de Leeuw, Dago M.

    2016-09-01

    We demonstrate that ferroelectric memory diodes can be utilized as switching type positive temperature coefficient (PTC) thermistors. The diode consists of a phase separated blend of a ferroelectric and a semiconducting polymer stacked between two electrodes. The current through the semiconducting polymer depends on the ferroelectric polarization. At the Curie temperature the ferroelectric polymer depolarizes and consequently the current density through the semiconductor decreases by orders of magnitude. The diode therefore acts as switching type PTC thermistor. Unlike their inorganic counterparts, the PTC thermistors presented here are thin film devices. The switching temperature can be tuned by varying the Curie temperature of the ferroelectric polymer.

  12. [Commonwealth Fund Survey 2012: Survey of Primary Care Doctors in 11 Countries: Use of Health Information Technology and Important Aspects of Care].

    Science.gov (United States)

    Hertle, D; Stock, S

    2015-09-01

    In 2006 and 2009 the US-American Commonwealth Fund (CMWF) already conducted international surveys with primary care physicians regarding their daily work and important aspects of care. In 2012 a third survey took place in 11 countries, with an emphasis on use of information technology. There was a written survey and a telephone survey of primary care physicians conducted in eleven industrial countries. In Germany, a random sample of 4 500 primary care physicians out of all 16 federal states were contacted by mail between April and July 2012. The data acquisition in Germany was conducted by the BQS Institute for Quality and Patient Safety and funded by the Federal Ministry of Health. The results were weighted by age, sex, region and medical specialty of the participating doctors. 9 776 primary care physicians participated; 909 of them in Germany. The response rate in Germany was 20%. 80% of the primary care physicians in Germany are using electronic patient records. But special IT functions, with the exception of electronic prescriptions and ordering of laboratory tests, are little used compared to other countries. Even in countries with a wide use of special IT functions within the practices, the possibility of communicating with colleagues and patients electronically is often lacking. 35% of the German primary care physicians think the quality of care has declined since the last survey in 2009. Only in France do more primary care physicians share that feeling (37%). In 2012 a lot more German primary care physicians stated to have problems with long waiting times for specialist consults (2009: 10%; 2012: 68%). © Georg Thieme Verlag KG Stuttgart · New York.

  13. Single-handed helical wrapping of single-walled carbon nanotubes by chiral, ionic, semiconducting polymers.

    Science.gov (United States)

    Deria, Pravas; Von Bargen, Christopher D; Olivier, Jean-Hubert; Kumbhar, Amar S; Saven, Jeffery G; Therien, Michael J

    2013-10-30

    We establish the requisite design for aryleneethynylene polymers that give rise to single-handed helical wrapping of single-walled carbon nanotubes (SWNTs). Highly charged semiconducting polymers that utilize either an (R)- or (S)-1,1'-bi-2-naphthol component in their respective conjugated backbones manifest HRTEM and AFM images of single-chain-wrapped SWNTs that reveal significant preferences for the anticipated helical wrapping handedness; statistical analysis of these images, however, indicates that ∼20% of the helical structures are formed with the "unexpected" handedness. CD spectroscopic data, coupled with TDDFT-based computational studies that correlate the spectral signatures of semiconducting polymer-wrapped SWNT assemblies with the structural properties of the chiral 1,1'-binaphthyl unit, suggest strongly that two distinct binaphthalene SWNT binding modes, cisoid-facial and cisoid-side, are possible for these polymers, with the latter mode responsible for inversion of helical chirality and the population of polymer-SWNT superstructures that feature the unexpected polymer helical wrapping chirality at the nanotube surface. Analogous aryleneethynylene polymers were synthesized that feature a 2,2'-(1,3-benzyloxy)-bridged (b)-1,1'-bi-2-naphthol unit: this 1,1'-bi-2-naphthol derivative is characterized by a bridging 2,2'-1,3 benzyloxy tether that restricts the torsional angle between the two naphthalene subunits along its C1-C1' chirality axis to larger, oblique angles that facilitate more extensive van der Waals contact of the naphthyl subunits with the nanotube. Similar microscopic, spectroscopic, and computational studies determine that chiral polymers based on conformationally restricted transoid binaphthyl units direct preferential facial binding of the polymer with the SWNT and thereby guarantee helically wrapped polymer-nanotube superstructures of fixed helical chirality. Molecular dynamics simulations provide an integrated picture tying together the

  14. Investigation of semiconducting YBaCuO thin films: A new room temperature bolometer

    Energy Technology Data Exchange (ETDEWEB)

    Shan, P.C.; Celik-Butler, Z.; Butler, D.P.; Jahanzeb, A.; Travers, C.M. [Department of Electrical Engineering, Southern Methodist University, Dallas, Texas 75275-0338 (United States); Kula, W.; Sobolewski, R. [Department of Electrical Engineering and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14627 (United States)

    1996-12-01

    We explore the application of the semiconducting phases of YBaCuO thin films as a bolometer for uncooled infrared detection. For this study, four different structures were built with different types of buffer layers: YBaCuO on a Si substrate with and without a MgO buffer layer, and on an oxidized Si substrate with and without a MgO buffer layer. These films were all amorphous without a detectable long range order. For comparison, crystalline tetragonal YBa{sub 2}Cu{sub 3}O{sub 6.5} and YBa{sub 2}Cu{sub 3}O{sub 6.3} thin films on a LaAlO{sub 3} substrate were included into the study. All six films exhibited semiconducting resistance versus temperature characteristics. The bolometer figures of merit, responsivity, and detectivity were calculated from the measured temperature coefficient of resistance (TCR) and the inherent noise characteristics of the temperature sensing element. The room temperature TCRs for all four amorphous films were greater than 2.5{percent} K{sup {minus}1}. The highest TCR of 4.02{percent} K{sup {minus}1} was observed on the amorphous YBaCuO thin film deposited on MgO/Si without a SiO{sub 2} layer. The TCR of the tetragonal films, on the other hand, remained 2{percent} K{sup {minus}1} or less in the same temperature range. Noise measurements performed in the 1{endash}100 Hz frequency range revealed a quadratic dependence on the bias current as would be expected from ohmic electrical characteristics. The Johnson and 1/{ital f} regions were clearly identified in the noise spectrum. From TCR and noise measurements, we estimated the amorphous semiconducting YBaCuO bolometers would have a responsivity as high as 3.8{times}10{sup 5} V/W and a detectivity as high as 1.6{times}10{sup 9} cmHz{sup 1/2}/W for 1 {mu}A bias current and frame frequency of 30 Hz if integrated with a typical air-gap thermal isolation structure. {copyright} {ital 1996 American Institute of Physics.}

  15. Electronic Structure of Semiconducting and Metallic Tubes in TiO2/Carbon Nanotube Heterojunctions: Density Functional Theory Calculations.

    Science.gov (United States)

    Long, Run

    2013-04-18

    The electronic structure of the TiO2(110) surface interfaced with both a semiconducting and metallic carbon nanotube (CNT) was investigated by density functional theory. Our simulations rationalized visible light photocatalytic activity of CNT/TiO2 hybrid materials higher than that under ultraviolent irradiation and showed that the photoactivity of a semiconducting CNT decorating TiO2 is better than that of the metallic CNT/TiO2 system due to efficient charge separation across the interface. This suggests that semiconducting CNT/TiO2 could be a potential photovoltaic material. In contrast, strong interaction between a metallic CNT and TiO2 leads to large charge transfer. Such charge transfer reduces the built-in potential, in turn resulting in inefficient charge separation. Functionalizing the metallic CNT with a small platinum cluster can increase the built-in potential and drive charge separation. These observations indicate that the CNT/TiO2 interface can be a potential photovoltaic material by a metal cluster decorating a CNT despite a real tube being composed of the mixture of metallic and semiconducting CNTs.

  16. Vectorial mapping of noncollinear antiferromagnetic structure of semiconducting FeSe surface with spin-polarized scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, K. F.; Yang, Fang; Song, Y. R. [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Xiaole [Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240 (China); The State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Chen, Xianfeng [The State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Canhua; Qian, Dong; Gao, C. L., E-mail: clgao@sjtu.edu.cn; Jia, Jin-Feng [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China); Luo, Weidong, E-mail: wdluo@sjtu.edu.cn [Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)

    2016-02-08

    Antiferromagnetic semiconductors gain increasing interest due to their possible application in spintronics. Using spin polarized scanning tunneling microscopy operating in a vector field, we mapped the noncollinear antiferromagnetic spin structure of a semiconducting hexagonal FeSe surface on the atomic scale. The surface possesses an in-plane compensated Néel structure which is further confirmed by first-principles calculations.

  17. Semiconducting properties of oxide films formed onto an Nb electrode in NaOH solutions

    Directory of Open Access Journals (Sweden)

    VLADIMIR D. JOVIC

    2008-03-01

    Full Text Available In this paper, the results of the potentiostatic formation of homogeneous and heterogeneous, nano-crystalline passive films of Nb2O5 onto an Nb electrode in NaOH solutions of different concentrations at potentials lower than 3.0 V vs. SCE are presented. The semiconducting properties of such films were investigated by EIS measurements. After fitting the EIS results by appropriate equivalent circuits, the space charge capacitance (Csc and space charge resistance (Rsc of these films were determined. The donor density (Nsc, flat band potential (Efb and thickness of the space charge layer (dsc for such oxide films were determined from the corresponding Mott–Schottky (M–S plots. It is shown that all oxide films were n-type semiconductors in a certain potential range.

  18. Spin-Dependent Goos-Hanchen Effect in Semiconducting Quantum Dots

    Science.gov (United States)

    Abdelrazek, Ahmed S.; Zein, Walid A.; Phillips, Adel H.

    2013-08-01

    The present research is devoted to the investigation of the spin-dependant Goos-Hanchen phase shift in quantum nanodevice. This nanodevice is modeled as semiconducting quantum dot coupled to two ferromagnetic leads. The spin transport through such nanodevice is conducted under the effect of both magnetic field and the photon energy of the induced ac-field. The angle of incidence of electrons is taken into account. Results show that the Goos-Hanchen phase shift of spin-up electrons is different from that of spin-down electron. Also, spin polarization and giant magneto-resistance are strongly depending on the angle of incidence of electrons and the photon energy of the induced ac-field. The present model could realize experimentally the spin beam splitter and spin filter needed for spin qubits and quantum information processing.

  19. Transparent ferrimagnetic semiconducting CuCr2O4 thin films by atomic layer deposition

    Science.gov (United States)

    Tripathi, T. S.; Yadav, C. S.; Karppinen, M.

    2016-04-01

    We report the magnetic and optical properties of CuCr2O4 thin films fabricated by atomic layer deposition (ALD) from Cu(thd)2, Cr(acac)3, and ozone; we deposit 200 nm thick films and anneal them at 700 °C in oxygen atmosphere to crystallize the spinel phase. A ferrimagnetic transition at 140 K and a direct bandgap of 1.36 eV are determined for the films from magnetic and UV-vis spectrophotometric measurements. Electrical transport measurements confirm the p-type semiconducting behavior of the films. As the ALD technique allows the deposition of conformal pin-hole-free coatings on complex 3D surfaces, our CuCr2O4 films are interesting material candidates for various frontier applications.

  20. Itinerant magnetism in doped semiconducting β-FeSi₂ and CrSi₂.

    Science.gov (United States)

    Singh, David J; Parker, David

    2013-12-17

    Novel or unusual magnetism is a subject of considerable interest, particularly in metals and degenerate semiconductors. In such materials the interplay of magnetism, transport and other Fermi liquid properties can lead to fascinating physical behavior. One example is in magnetic semiconductors, where spin polarized currents may be controlled and used. We report density functional calculations predicting magnetism in doped semiconducting β-FeSi₂ and CrSi₂ at relatively low doping levels particularly for n-type. In this case, there is a rapid cross-over to a half-metallic state as a function of doping level. The results are discussed in relation to the electronic structure and other properties of these compounds.

  1. Highly selective sorting of semiconducting single wall carbon nanotubes exhibiting light emission at telecom wavelengths

    Institute of Scientific and Technical Information of China (English)

    Francesco Sarti; Francesco Biccari; Federica Fioravanti; Ughetta Torrini; Anna Vinattieri; Vincent Derycke; Massimo Gurioli

    2016-01-01

    Single wall carbon nanotubes (SWNTs) are known for their exceptional electronic properties.However,most of the synthesis methods lead to the production of a mixture of carbon nanotubes having different chiralities associated with metallic (m-SWNTs) and semiconducting (s-SWNTs) characteristics.For application purposes,effective methods for separating these species are highly desired.Here,we report a protocol for achieving a highly selective separation of s-SWNTs that exhibit a fundamental optical transition centered at 1,550 nm.We employ a polymer assisted sorting approach,and the influence of preparation methods on the optical and transport performances of the separated nanotubes is analyzed.As even traces of m-SWNTs can critically affect performances,we aim to produce samples that do not contain any detectable fraction of residual m-SWNTs.

  2. Energy Band Gap Study of Semiconducting Single Walled Carbon Nanotube Bundle

    Science.gov (United States)

    Elkadi, Asmaa; Decrossas, Emmanuel; El-Ghazaly, Samir

    2013-01-01

    The electronic properties of multiple semiconducting single walled carbon nanotubes (s-SWCNTs) considering various distribution inside a bundle are studied. The model derived from the proposed analytical potential function of the electron density for an individual s-SWCNT is general and can be easily applied to multiple nanotubes. This work demonstrates that regardless the number of carbon nanotubes, the strong coupling occurring between the closest neighbours reduces the energy band gap of the bundle by 10%. As expected, the coupling is strongly dependent on the distance separating the s-SWCNTs. In addition, based on the developed model, it is proposed to enhance this coupling effect by applying an electric field across the bundle to significantly reduce the energy band gap of the bundle by 20%.

  3. Energy Band Gap Study of Semiconducting Single Walled Carbon Nanotube Bundle

    Science.gov (United States)

    Elkadi, Asmaa; Decrossas, Emmanuel; El-Ghazaly, Samir

    2013-01-01

    The electronic properties of multiple semiconducting single walled carbon nanotubes (s-SWCNTs) considering various distribution inside a bundle are studied. The model derived from the proposed analytical potential function of electron density for na individual s-SWCNT is general and can be easily applied to multiple nanotubes. This work demonstrates that regardless the number of carbon nanotubes, the strong coupling occurring between the closet neighbors reduces the energy band gap of the bundle by 10%. As expected, the coupling is strongly dependent on the distance separating the s-SWCNTs. In addition, based on the developed model, it is proposed to enhance this coupling effect by applying an electric field across the bundle to significantly reduce the energy band gap of the bundle by 20%.

  4. Semiconducting behavior of the anodically passive films formed on AZ31B alloy

    Directory of Open Access Journals (Sweden)

    A. Fattah-alhosseini

    2014-12-01

    Full Text Available This work includes determination of the semiconductor character and estimation of the dopant levels in the passive film formed on AZ31B alloy in 0.01 M NaOH, as well as the estimation of the passive film thickness as a function of the film formation potential. Mott–Schottky analysis revealed that the passive films displayed n-type semiconductive characteristics, where the oxygen vacancies and interstitials preponderated. Based on the Mott–Schottky analysis, it was shown that the calculated donor density increases linearly with increasing the formation potential. Also, the electrochemical impedance spectroscopy (EIS results indicated that the thickness of the passive film was decreased linearly with increasing the formation potential. The results showed that decreasing the formation potential offer better conditions for forming the passive films with higher protection behavior, due to the growth of a much thicker and less defective films.

  5. Integration of Semiconducting Sulfides for Full-Spectrum Solar Energy Absorption and Efficient Charge Separation.

    Science.gov (United States)

    Zhuang, Tao-Tao; Liu, Yan; Li, Yi; Zhao, Yuan; Wu, Liang; Jiang, Jun; Yu, Shu-Hong

    2016-05-23

    The full harvest of solar energy by semiconductors requires a material that simultaneously absorbs across the whole solar spectrum and collects photogenerated electrons and holes separately. The stepwise integration of three semiconducting sulfides, namely ZnS, CdS, and Cu2-x S, into a single nanocrystal, led to a unique ternary multi-node sheath ZnS-CdS-Cu2-x S heteronanorod for full-spectrum solar energy absorption. Localized surface plasmon resonance (LSPR) in the nonstoichiometric copper sulfide nanostructures enables effective NIR absorption. More significantly, the construction of pn heterojunctions between Cu2-x S and CdS leads to staggered gaps, as confirmed by first-principles simulations. This band alignment causes effective electron-hole separation in the ternary system and hence enables efficient solar energy conversion.

  6. Energy Band Gap Study of Semiconducting Single Walled Carbon Nanotube Bundle

    Science.gov (United States)

    Elkadi, Asmaa; Decrossas, Emmanuel; El-Ghazaly, Samir

    2013-01-01

    The electronic properties of multiple semiconducting single walled carbon nanotubes (s-SWCNTs) considering various distribution inside a bundle are studied. The model derived from the proposed analytical potential function of the electron density for an individual s-SWCNT is general and can be easily applied to multiple nanotubes. This work demonstrates that regardless the number of carbon nanotubes, the strong coupling occurring between the closest neighbours reduces the energy band gap of the bundle by 10%. As expected, the coupling is strongly dependent on the distance separating the s-SWCNTs. In addition, based on the developed model, it is proposed to enhance this coupling effect by applying an electric field across the bundle to significantly reduce the energy band gap of the bundle by 20%.

  7. Narrow-gap semiconducting properties of KMgBi with multiband feature

    Science.gov (United States)

    Zhang, Xiao; Sun, Shanshan; Lei, Hechang

    2017-01-01

    KMgBi single crystals have been grown successfully by using the Bi flux method. KMgBi shows a semiconducting behavior with a metal-semiconductor transition in high temperature regions. Moreover, both electron- and hole-type carriers exist in KMgBi with a strong temperature dependence of carrier concentrations and mobilities. These results suggest that KMgBi is a narrow-band semiconductor with multiband features in the bulk rather than a semimetal as predicted theoretically. On the other hand, KMgBi exhibits a resistivity plateau in low temperature regions, similar to other topological insulators. It implies that there might be a nontrivial topological surface state in KMgBi.

  8. Semiconducting-to-Metallic Photoconductivity Crossover and Temperature-Dependent Drude Weight in Graphene

    Science.gov (United States)

    Frenzel, A. J.; Lui, C. H.; Shin, Y. C.; Kong, J.; Gedik, N.

    2014-08-01

    We investigate the transient photoconductivity of graphene at various gate-tuned carrier densities by optical-pump terahertz-probe spectroscopy. We demonstrate that graphene exhibits semiconducting positive photoconductivity near zero carrier density, which crosses over to metallic negative photoconductivity at high carrier density. These observations can be accounted for by the interplay between photoinduced changes of both the Drude weight and carrier scattering rate. Our findings provide a complete picture to explain the opposite photoconductivity behavior reported in (undoped) graphene grown epitaxially and (doped) graphene grown by chemical vapor deposition. Notably, we observe nonmonotonic fluence dependence of the photoconductivity at low carrier density. This behavior reveals the nonmonotonic temperature dependence of the Drude weight in graphene, a unique property of two-dimensional massless Dirac fermions.

  9. Controlling the Self-Assembly of Semiconducting Nanocrystals within Conjugated Rod-Coil Block Copolymers

    Science.gov (United States)

    McCulloch, Bryan L.; Urban, Jeff J.; Segalman, Rachel A.

    2010-03-01

    Blends of conjugated polymers and inorganic nanoparticles have been investigated for numerous optoelectronic applications however optimization relies on precise control over the nanoscale morphologies. Here, we show that conjugated rod-coil block copolymers can be designed to self assemble into controllable morphologies with the coil block templating nanocrystal location. We have constructed a model system where nanocrystals are blended with poly(alkoxy-phenylene vinylene-b-2-vinylpyridine) (PPV-b-P2VP), which self assembles into tunable morphologies. Semiconducting nanocrystals reside within the P2VP domain, due to the favorable interactions between P2VP and the nanoparticle surface as well as the exclusionary effects of the liquid crystalline PPV. The placement of the nanoparticles can be tuned by altering domain size, nanocrystal diameter and nanocrystal surface chemistry. These findings are used to develop a comprehensive understanding of the self assembly processes in conjugated rod-coil block copolymer nanocomposites.

  10. Dithiopheneindenofluorene (TIF) Semiconducting Polymers with Very High Mobility in Field-Effect Transistors

    KAUST Repository

    Chen, Hu

    2017-07-19

    The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone. A range of copolymers are prepared and their electrical properties and thin-film morphology evaluated, with the co-benzothiadiazole polymer having a twofold increase in hole mobility when compared to the IDT analog, reaching values of almost 3 cm2 V−1 s−1 in bottom-gate top-contact organic field-effect transistors.

  11. Semiconducting Properties of Swift Au Ion-Irradiated ZnO Thin Films at Room Temperature

    Science.gov (United States)

    Kwon, Sera; Park, Hyun-Woo; Chung, Kwun-Bum

    2017-02-01

    The semiconducting properties of Au ion-irradiated ZnO thin films were investigated as a function of ion irradiation dose at room temperature. The Au ion irradiation was conducted with acceleration energy of 130 MeV in the ion dose range from 1 × 1011 to 5 × 1012 ions/cm2. The physical properties showed no change regardless of the Au ion irradiation dose; however, the electrical properties of Au ion-irradiated ZnO thin films changed, depending on the Au ion irradiation dose. The electronic structure drastically changed with the evolution of hybridized molecular orbital structure for the conduction band and band edge states below the conduction band. These remarkable changes in electronic structure correlate with changes in electrical properties, such as carrier concentration and mobility.

  12. Transparent ferrimagnetic semiconducting CuCr2O4 thin films by atomic layer deposition

    Directory of Open Access Journals (Sweden)

    T. S. Tripathi

    2016-04-01

    Full Text Available We report the magnetic and optical properties of CuCr2O4 thin films fabricated by atomic layer deposition (ALD from Cu(thd2, Cr(acac3, and ozone; we deposit 200 nm thick films and anneal them at 700 °C in oxygen atmosphere to crystallize the spinel phase. A ferrimagnetic transition at 140 K and a direct bandgap of 1.36 eV are determined for the films from magnetic and UV-vis spectrophotometric measurements. Electrical transport measurements confirm the p-type semiconducting behavior of the films. As the ALD technique allows the deposition of conformal pin-hole-free coatings on complex 3D surfaces, our CuCr2O4 films are interesting material candidates for various frontier applications.

  13. Investigation of compositional segregation during unidirectional solidification of solid solution semiconducting alloys

    Science.gov (United States)

    Wang, J. C.

    1982-01-01

    Compositional segregation of solid solution semiconducting alloys in the radial direction during unidirectional solidification was investigated by calculating the effect of a curved solid liquid interface on solute concentration at the interface on the solid. The formulation is similar to that given by Coriell, Boisvert, Rehm, and Sekerka except that a more realistic cylindrical coordinate system which is moving with the interface is used. Analytical results were obtained for very small and very large values of beta with beta = VR/D, where V is the velocity of solidification, R the radius of the specimen, and D the diffusivity of solute in the liquid. For both very small and very large beta, the solute concentration at the interface in the solid C(si) approaches C(o) (original solute concentration) i.e., the deviation is minimal. The maximum deviation of C(si) from C(o) occurs for some intermediate value of beta.

  14. Heavy metallic oxide nanoparticles for enhanced sensitivity in semiconducting polymer x-ray detectors.

    Science.gov (United States)

    Intaniwet, A; Mills, C A; Shkunov, M; Sellin, P J; Keddie, J L

    2012-06-15

    Semiconducting polymers have previously been used as the transduction material in x-ray dosimeters, but these devices have a rather low detection sensitivity because of the low x-ray attenuation efficiency of the organic active layer. Here, we demonstrate a way to overcome this limitation through the introduction of high density nanoparticles having a high atomic number (Z) to increase the x-ray attenuation. Specifically, bismuth oxide (Bi(2)O(3)) nanoparticles (Z = 83 for Bi) are added to a poly(triarylamine) (PTAA) semiconducting polymer in the active layer of an x-ray detector. Scanning electron microscopy (SEM) reveals that the Bi(2)O(3) nanoparticles are reasonably distributed in the PTAA active layer. The reverse bias dc current-voltage characteristics for PTAA-Bi(2)O(3) diodes (with indium tin oxide (ITO) and Al contacts) have similar leakage currents to ITO/PTAA/Al diodes. Upon irradiation with 17.5 keV x-ray beams, a PTAA device containing 60 wt% Bi(2)O(3) nanoparticles demonstrates a sensitivity increase of approximately 2.5 times compared to the plain PTAA sensor. These results indicate that the addition of high-Z nanoparticles improves the performance of the dosimeters by increasing the x-ray stopping power of the active volume of the diode. Because the Bi(2)O(3) has a high density, it can be used very efficiently, achieving a high weight fraction with a low volume fraction of nanoparticles. The mechanical flexibility of the polymer is not sacrificed when the inorganic nanoparticles are incorporated.

  15. Spin-orbital coupling effect on the power factor in semiconducting transition-metal dichalcogenide monolayers

    Science.gov (United States)

    Guo, San-Dong; Wang, Jian-Li

    2016-09-01

    The electronic structures and thermoelectric properties of semiconducting transition-metal dichalcogenide monolayers {{MX}}2 (M = Zr, Hf, Mo, W and Pt; X = S, Se and Te) are investigated by combining first-principles and Boltzmann transport theory, including spin-orbital coupling (SOC). It is found that the gap decrease increases from S to Te in each cation group when the SOC is opened. The spin-orbital splitting has the same trend with the gap reducing. The calculated results show that SOC has a noteworthy detrimental effect on the p-type power factor, while it has a negligible influence in n-type doping except for the W cation group, which can be understood by considering the effects of SOC on the valence and conduction bands. For {{WX}}2 (X = S, Se and Te), SOC leads to an observable enhanced power factor in n-type doping, which can be explained by SOC-induced band degeneracy, namely the bands converge. Among all of the cation groups, the Pt cation group shows the highest Seebeck coefficient, which leads to the best power factor, if we assume that the scattering time is fixed. The calculated results show that {{MS}}2 (M = Zr, Hf, Mo, W and Pt) have the best p-type power factor of all the cation groups, and that {{MSe}}2 (M = Zr and Hf), {{WS}}2 and {{MTe}}2 (M = Mo and Pt) have a more excellent n-type power factor in their respective cation group. Therefore, these results may be useful for further theoretical prediction or experimental research of excellent thermoelectric materials from semiconducting transition-metal dichalcogenide monolayers.

  16. Exploring the potential of semiconducting BaSi2 for thin-film solar cell applications

    Science.gov (United States)

    Suemasu, Takashi; Usami, Noritaka

    2017-01-01

    Semiconducting barium disilicide (BaSi2), which is composed of earth-abundant elements, has attractive features for thin-film solar cell applications. Both a large absorption coefficient comparable to copper indium gallium diselenide and a minority-carrier diffusion length much larger than the grain size of BaSi2 can be used to improve solar cell properties. In this review article, we explore the potential of semiconducting BaSi2 film for thin-film solar cell applications. We start by describing its crystal and energy band structure, followed by discussing thin-film growth techniques and the optical and electrical properties of BaSi2 films. We use a first-principles calculation based on density-functional theory to calculate the position of the Fermi level to predict the carrier type of impurity-doped BaSi2 films using either a group 13 or 15 element, and compare the calculated results with the experimental ones. Special attention was paid to the minority-carrier properties, such as minority-carrier lifetime, minority-carrier diffusion length, and surface passivation. The potential variations across the grain boundaries measured by Kelvin-probe force microscopy allowed us to detect a larger minority-carrier diffusion length in BaSi2 on Si(1 1 1) compared with BaSi2 on Si(0 0 1). Finally, we demonstrate the operation of p-BaSi2/n-Si heterojunction solar cells and discuss prospects for future development.

  17. Crystal Growth of II-VI Semiconducting Alloys by Directional Solidification

    Science.gov (United States)

    Lehoczky, Sandor L.; Szofran, Frank R.; Su, Ching-Hua; Cobb, Sharon D.; Scripa, Rosalia A.; Sha, Yi-Gao

    1999-01-01

    This research study is investigating the effects of a microgravity environment during the crystal growth of selected II-VI semiconducting alloys on their compositional, metallurgical, electrical and optical properties. The on-going work includes both Bridgman-Stockbarger and solvent growth methods, as well as growth in a magnetic field. The materials investigated are II-VI, Hg(1-x)Zn(x)Te, and Hg(1-x)Zn(x)Se, where x is between 0 and 1 inclusive, with particular emphasis on x-values appropriate for infrared detection and imaging in the 5 to 30 micron wavelength region. Wide separation between the liquidus and solidus of the phase diagrams with consequent segregation during solidification and problems associated with the high volatility of one of the components (Hg), make the preparation of homogeneous, high-quality, bulk crystals of the alloys an extremely difficult nearly an impossible task in a gravitational environment. The three-fold objectives of the on-going investigation are as follows: (1) To determine the relative contributions of gravitationally-driven fluid flows to the compositional redistribution observed during the unidirectional crystal growth of selected semiconducting solid solution alloys having large separation between the liquidus and solidus of the constitutional phase diagram; (2) To ascertain the potential role of irregular fluid flows and hydrostatic pressure effects in generation of extended crystal defects and second-phase inclusions in the crystals; and, (3) To obtain a limited amount of "high quality" materials needed for bulk crystal property characterizations and for the fabrication of various device structures needed to establish ultimate material performance limits. The flight portion of the study was to be accomplished by performing growth experiments using the Crystal Growth Furnace (CGF) manifested to fly on various Spacelab missions.

  18. Semiconducting organic-inorganic nanocomposites by intimately tethering conjugated polymers to inorganic tetrapods

    Science.gov (United States)

    Jung, Jaehan; Yoon, Young Jun; Lin, Zhiqun

    2016-04-01

    Semiconducting organic-inorganic nanocomposites were judiciously crafted by placing conjugated polymers in intimate contact with inorganic tetrapods via click reaction. CdSe tetrapods were first synthesized by inducing elongated arms from CdSe zincblende seeds through seed-mediated growth. The subsequent effective inorganic ligand treatment, followed by reacting with short bifunctional ligands, yielded azide-functionalized CdSe tetrapods (i.e., CdSe-N3). Finally, the ethynyl-terminated conjugated polymer poly(3-hexylthiophene) (i.e., P3HT-&z.tbd;) was tethered to CdSe-N3 tetrapods via a catalyst-free alkyne-azide cycloaddition, forming intimate semiconducting P3HT-CdSe tetrapod nanocomposites. Intriguingly, the intimate contact between P3HT and CdSe tetrapod was found to not only render the effective dispersion of CdSe tetrapods in the P3HT matrix, but also facilitate the efficient electronic interaction between these two semiconducting constituents. The successful anchoring of P3HT chains onto CdSe tetrapods was substantiated through Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy measurements. Moreover, the absorption and photoluminescence studies further corroborated the intimate tethering between P3HT and CdSe tetrapods. The effect of the type of bifunctional ligands (i.e., aryl vs. aliphatic ligands) and the size of tetrapods on the device performance of hybrid organic-inorganic solar cells was also scrutinized. Interestingly, P3HT-CdSe tetrapod nanocomposites produced via the use of an aryl bifunctional ligand (i.e., 4-azidobenzoic acid) exhibited an improved photovoltaic performance compared to that synthesized with their aliphatic ligand counterpart (i.e., 5-bromovaleric acid). Clearly, the optimal size of CdSe tetrapods ensuring the effective charge transport in conjunction with the good dispersion of CdSe tetrapods rendered an improved device performance. We envision that the click-reaction strategy enabled by

  19. Which Elementary School Subjects Are the Most Likeable, Most Important, and the Easiest? Why?: A Study of Science and Technology, Mathematics, Social Studies, and Turkish

    Science.gov (United States)

    Dündar, Sahin; Güvendir, Meltem Acar; Kocabiyik, Oya Onat; Papatga, Erdal

    2014-01-01

    The present study was conducted first to identify which school subjects were most liked, most important, and most difficult, as well as least liked, least important and easiest as perceived by elementary school students and second to explore the reasons why students most/least liked, considered as most/least important, and considered as most…

  20. Development and Application of Gas Sensing Technologies to Enable Boiler Balancing

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Prabir

    2008-12-31

    Identifying gas species and their quantification is important for optimization of many industrial applications involving high temperatures, including combustion processes. CISM (Center for Industrial Sensors and Measurements) at the Ohio State University has developed CO, O{sub 2}, NO{sub x}, and CO{sub 2} sensors based on TiO{sub 2} semiconducting oxides, zirconia and lithium phosphate based electrochemical sensors and sensor arrays for high-temperature emission control. The underlying theme in our sensor development has been the use of materials science and chemistry to promote high-temperature performance with selectivity. A review article presenting key results of our studies on CO, NO{sub x}, CO{sub 2} and O{sub 2} sensors is described in: Akbar, Sheikh A.; Dutta, Prabir K. Development and Application of Gas Sensing Technologies for Combustion Processes, PowerPlant Chemistry, 9(1) 2006, 28-33.

  1. The Extent of Al-Balqa Applied University's Students' Perception of the Importance of Means of Information and Communication Technology in High Education in Jordan

    Science.gov (United States)

    Al Zou'bi, Abdallah S.; Al-Onizat, Sabah

    2015-01-01

    This study aimed to identify the effectiveness of using information technology and communications' means in the academic education from the perspective of Al-Balqa Applied University's students. And to achieve this goal, the researchers prepared and developed a questionnaire as a tool of the study including 26 items. The population of the study,…

  2. Investigation of spin-gapless semiconductivity and half-metallicity in Ti{sub 2}MnAl-based compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lukashev, P., E-mail: pavel.lukashev@uni.edu; Staten, B.; Hurley, N. [Department of Physics, University of Northern Iowa, Cedar Falls, Iowa 50614 (United States); Kharel, P., E-mail: parashu.kharel@sdstate.edu [Department of Physics, South Dakota State University, Brookings, South Dakota 57007 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States); Gilbert, S.; Fuglsby, R.; Huh, Y. [Department of Physics, South Dakota State University, Brookings, South Dakota 57007 (United States); Valloppilly, S. [Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States); Zhang, W.; Skomski, R.; Sellmyer, D. J. [Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States); Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Yang, K. [Department of Physics, South Dakota State University, Brookings, South Dakota 57007 (United States); College of Mechanical and Electrical Engineering, Hohai University, Changzhou, Jiangsu 213022 (China)

    2016-04-04

    The increasing interest in spin-based electronics has led to a vigorous search for new materials that can provide a high degree of spin polarization in electron transport. An ideal candidate would act as an insulator for one spin channel and a conductor or semiconductor for the opposite spin channel, corresponding to the respective cases of half-metallicity and spin-gapless semiconductivity. Our first-principle electronic-structure calculations indicate that the metallic Heusler compound Ti{sub 2}MnAl becomes half-metallic and spin-gapless semiconducting if half of the Al atoms are replaced by Sn and In, respectively. These electronic structures are associated with structural transitions from the regular cubic Heusler structure to the inverted cubic Heusler structure.

  3. Electrical behavior of Langmuir-Blodgett networks of sorted metallic and semiconducting single-walled carbon nanotubes.

    Science.gov (United States)

    Massey, Mark K; Rosamond, Mark C; Pearson, Christopher; Zeze, Dagou A; Petty, Michael C

    2012-10-30

    Langmuir-Blodgett deposition has been used to form thin film networks of both metallic and semiconducting single-walled carbon nanotubes. These have been investigated to understand their physical, optical, and morphological properties. The electrical conductivities over the temperature range 80-350 K and across electrode gaps of 220 nm and 2 mm have been explored. In the case of semiconducting tubes, the results suggest that Poole-Frenkel conduction is the dominant electrical process at temperatures below 150 K and electric fields of greater than 1 MV m(-1). Metallic nanotube networks exhibit a decrease in resistance with a reduction in temperature. This can be approximated by a linear relationship, giving a temperature coefficient of resistance of 10(-3) K(-1).

  4. Toward Low-Voltage and Bendable X-Ray Direct Detectors Based on Organic Semiconducting Single Crystals.

    Science.gov (United States)

    Ciavatti, Andrea; Capria, Ennio; Fraleoni-Morgera, Alessandro; Tromba, Giuliana; Dreossi, Diego; Sellin, Paul J; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

    2015-11-25

    Organic materials have been mainly proposed as ionizing radiation detectors in the indirect conversion approach. The first thin and bendable X-ray direct detectors are realized (directly converting X-photons into an electric signal) based on organic semiconducting single crystals that possess enhanced sensitivity, low operating voltage (≈5 V), and a minimum detectable dose rate of 50 μGy s(-1) .

  5. CO{sub 2} reduction consensus?. A conceptual framework for global CO{sub 2} reduction targets: The importance of energy technology development

    Energy Technology Data Exchange (ETDEWEB)

    Okken, P.A.

    1991-12-01

    This paper starts with the Intergovernmental Panel on Climate Change, Science Group`s recommendation to reduce global fossil fuel CO{sub 2} emissions by 60% at least. This recommendation is considered to be the result of a utilitarian consensus process, which takes into account the current knowledge about CO{sub 2} reduction costs in national energy systems, and the scientific uncertainties in global climate change assessments. A conceptual framework for this consensus reaching process is constructed, and various arguments and issues are discussed, leading to higher or lower CO{sub 2} reduction percentages. One of these arguments is that with new energy technologies more than 60% CO{sub 2} reduction is possible. This is illustrated for the transport sector and coal power generation (together contributing 45% to current global emissions). Although CO{sub 2} reduction in these sectors is generally thought to be very difficult, yet new energy technologies are available to drastically reduce emissions, cost-effective in the range of 25 to 100$/tCO{sub 2} reduced. 11 figs., 6 tabs., 14 refs.

  6. Facile Isolation of Adsorbent-Free Long and Highly-Pure Chirality-Selected Semiconducting Single-Walled Carbon Nanotubes Using A Hydrogen-bonding Supramolecular Polymer

    Science.gov (United States)

    Toshimitsu, Fumiyuki; Nakashima, Naotoshi

    2015-12-01

    The ideal form of semiconducting-single-walled carbon nanotubes (sem-SWNTs) for science and technology is long, defect-free, chirality pure and chemically pure isolated narrow diameter tubes. While various techniques to solubilize and purify sem-SWNTs have been developed, many of them targeted only the chiral- or chemically-purity while sacrificing the sem-SWNT intrinsic structural identities by applying strong ultra-sonication and/or chemical modifications. Toward the ultimate purification of the sem-SWNTs, here we report a mild-conditioned extraction of the sem-SWNTs using removable supramolecular hydrogen-bonding polymers (HBPs) that are composed of dicarboxylic- or diaminopyridyl-fluorenes with ~70%-(8,6)SWNT selective extraction. Replacing conventional strong sonication techniques by a simple shaking using HPBs was found to provide long sem-SWNTs (>2.0 μm) with a very high D/G ratio, which was determined by atomic force microscopy observations. The HBPs were readily removed from the nanotube surfaces by an outer stimulus, such as a change in the solvent polarities, to provide chemically pure (8,6)-enriched sem-SWNTs. We also describe molecular mechanics calculations to propose possible structures for the HBP-wrapped sem-SWNTs, furthermore, the mechanism of the chiral selectivity for the sorted sem-SWNTs is well explained by the relationship between the molecular surface area and mass of the HBP/SWNT composites.

  7. Influence of metallic and semiconducting nanostructures on the optical properties of dye-doped polymer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Enculescu, M., E-mail: mdatcu@infim.ro; Matei, E.

    2016-09-01

    Dye-doped polymer thin films were obtained by spin-coating of 8% polyvinylpyrrolidone (PVP) solutions (in ethanol). Ni or ZnO nanowires were incorporated in Rhodamine 6G doped polymer films (10{sup −4} M dye concentration). Optical and morphological properties of simple dye-doped polymer films and films containing metallic or semiconducting nanostructures were investigated. Optical microscopy and scanning electron microscopy were used to image the nanowires. The presence of Ni nanowires induces a small shift (2–3 nm) to longer wavelengths on the emission band of Rh 6G doped PVP film. The ZnO nanowires' presence was confirmed by X-ray diffraction measurements. An enhancement of the emission of the dye doped polymer is induced by the semiconducting structures. - Highlights: • Rhodamine 6G doped polyvinylpyrrolidone thin films were obtained by spin-coating. • Ni or ZnO nanowires were incorporated in Rhodamine 6G doped polymer films. • Ni nanowires' presence induces a shift to shorter wavelengths on the emission band. • Enhancement of dye-doped polymer emission induced by the semiconducting structures.

  8. Photoluminescence mechanisms of metallic Zn nanospheres, semiconducting ZnO nanoballoons, and metal-semiconductor Zn/ZnO nanospheres

    Science.gov (United States)

    Lin, Jin-Han; Patil, Ranjit A.; Devan, Rupesh S.; Liu, Zhe-An; Wang, Yi-Ping; Ho, Ching-Hwa; Liou, Yung; Ma, Yuan-Ron

    2014-01-01

    We utilized a thermal radiation method to synthesize semiconducting hollow ZnO nanoballoons and metal-semiconductor concentric solid Zn/ZnO nanospheres from metallic solid Zn nanospheres. The chemical properties, crystalline structures, and photoluminescence mechanisms for the metallic solid Zn nanospheres, semiconducting hollow ZnO nanoballoons, and metal-semiconductor concentric solid Zn/ZnO nanospheres are presented. The PL emissions of the metallic Zn solid nanospheres are mainly dependent on the electron transitions between the Fermi level (EF) and the 3d band, while those of the semiconducting hollow ZnO nanoballoons are ascribed to the near band edge (NBE) and deep level electron transitions. The PL emissions of the metal-semiconductor concentric solid Zn/ZnO nanospheres are attributed to the electron transitions across the metal-semiconductor junction, from the EF to the valence and 3d bands, and from the interface states to the valence band. All three nanostructures are excellent room-temperature light emitters. PMID:25382186

  9. Printed thin film transistors and CMOS inverters based on semiconducting carbon nanotube ink purified by a nonlinear conjugated copolymer.

    Science.gov (United States)

    Xu, Wenya; Dou, Junyan; Zhao, Jianwen; Tan, Hongwei; Ye, Jun; Tange, Masayoshi; Gao, Wei; Xu, Weiwei; Zhang, Xiang; Guo, Wenrui; Ma, Changqi; Okazaki, Toshiya; Zhang, Kai; Cui, Zheng

    2016-02-28

    Two innovative research studies are reported in this paper. One is the sorting of semiconducting carbon nanotubes and ink formulation by a novel semiconductor copolymer and second is the development of CMOS inverters using not the p-type and n-type transistors but a printed p-type transistor and a printed ambipolar transistor. A new semiconducting copolymer (named P-DPPb5T) was designed and synthesized with a special nonlinear structure and more condensed conjugation surfaces, which can separate large diameter semiconducting single-walled carbon nanotubes (sc-SWCNTs) from arc discharge SWCNTs according to their chiralities with high selectivity. With the sorted sc-SWCNTs ink, thin film transistors (TFTs) have been fabricated by aerosol jet printing. The TFTs displayed good uniformity, low operating voltage (±2 V) and subthreshold swing (SS) (122-161 mV dec(-1)), high effective mobility (up to 17.6-37.7 cm(2) V(-1) s(-1)) and high on/off ratio (10(4)-10(7)). With the printed TFTs, a CMOS inverter was constructed, which is based on the p-type TFT and ambipolar TFT instead of the conventional p-type and n-type TFTs. Compared with other recently reported inverters fabricated by printing, the printed CMOS inverters demonstrated a better noise margin (74% 1/2 Vdd) and was hysteresis free. The inverter has a voltage gain of up to 16 at an applied voltage of only 1 V and low static power consumption.

  10. Thermal conductivity of organic semi-conducting materials using 3omega and photothermal radiometry techniques

    Directory of Open Access Journals (Sweden)

    Reisdorffer Frederic

    2014-01-01

    Full Text Available Organic semiconductors for opto-electronic devices show several defects which can be enhanced while increasing the operating temperature. Their thermal management and especially the reduction of their temperature are of great interest. For the heat transfer study, one has to measure the thermal conductivity of thin film organic materials. However the major difficulty for this measurement is the very low thickness of the films which needs the use of very specific techniques. In our work, the 3-omega and photothermal radiometric methods were used to measure the thermal conductivity of thin film organic semiconducting material (Alq3. The measurements were performed as function of the thin film thickness from 45 to 785 nm and also of its temperature from 80 to 350 K. With the 3 omega method, a thermal conductivity value of 0.066 W.m−1K−1 was obtained for Alq3 thin film of 200 nm at room temperature, in close agreement with the photothermal value. Both techniques appear to be complementary: the 3 omega method is easier to implement for large temperature range and small thicknesses down to a few tens of nanometers whereas the photothermal method is more suitable for thicknesses over 200nm since it provides additional information such as the thin film volumetric heat capacity.

  11. Glutathione responsive micelles incorporated with semiconducting polymer dots and doxorubicin for cancer photothermal-chemotherapy

    Science.gov (United States)

    Cai, Zhixiong; Zhang, Da; Lin, Xinyi; Chen, Yunzhu; Wu, Ming; Wei, Zuwu; Zhang, Zhenxi; Liu, Xiaolong; Yao, Cuiping

    2017-10-01

    Nanoplatform integrated with photothermal therapy (PTT) and chemotherapy has been recognized a promising agent for enhancing cancer therapeutic outcomes, but still suffer from less controllability for optimizing their synergistic effects. We fabricated glutathione (GSH) responsive micelles incorporated with semiconducting polymer dots and doxorubicin (referred as SPDOX NPs) for combining PTT with chemotherapy to enhance cancer therapeutic efficiency. These micelles, with excellent water dispersibility, comprises of three distinct functional components: (1) the monomethoxy-poly(ethylene glycol)-S-S-hexadecyl (mPEG-S-S-C16), which forms the micelles, can render hydrophobic substances water-soluble and improve the colloidal stability; (2) disulfide linkages can be cleaved in a reductive environment for tumor specific drug release due to the high GSH concentrations of tumor micro-environment; (3) PCPDTBT dots and anti-cancer drug DOX that are loaded inside the hydrophobic core of the micelle can be applied to simultaneously perform PTT and chemotherapy to achieve significantly enhanced tumor killing efficiency both in vitro and in vivo. In summary, our studies demonstrated that our SPDOX NPs with simultaneous photothermal-chemotherapy functions could be a promising platform for a tumor specific responsive drug delivery system.

  12. Linear and Nonlinear Rheology Combined with Dielectric Spectroscopy of Hybrid Polymer Nanocomposites for Semiconductive Applications

    Science.gov (United States)

    Kádár, Roland; Abbasi, Mahdi; Figuli, Roxana; Rigdahl, Mikael; Wilhelm, Manfred

    2017-01-01

    The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate) (EBA) nanocomposite hybrids containing graphite nanoplatelets (GnP) and carbon black (CB). The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests. PMID:28336857

  13. Efficient Naphthalenediimide-Based Hole Semiconducting Polymer with Vinylene Linkers between Donor and Acceptor Units

    KAUST Repository

    Zhang, Lei

    2016-11-04

    We demonstrate a new method to reverse the polarity and charge transport behavior of naphthalenediimide (NDI)-based copolymers by inserting a vinylene linker between the donor and acceptor units. The vinylene linkers minimize the intrinsic steric congestion between the NDI and thiophene moieties to prompt backbone planarity. The polymers with vinylene linkers exhibit electron n-channel transport characteristics under vacuum, similar to the benchmark polymer, P(NDI2OD-T2). To our surprise, when the polymers are measured in air, the dominant carrier type switches from n- to p-type and yield hole mobilities up to 0.45 cm(2) s(-1) with hole to electron mobility ratio of three (mu(h)/mu(e), similar to 3), which indicates that the hole density in the active layer can be significantly increased by exposure to air. This increase is consistent with the intrinsic more delocalized nature of the highest occupied molecular orbital of the charged vinylene polymer, as estimated by density functional theory (DFT) calculations, which facilitates hole transport within the polymer chains. This is the first demonstration of an efficient NDI-based hole semiconducting polymer, which will enable new developments in all-polymer solar cells, complementary circuits, and dopable polymers for use in thermoelectrics.

  14. Semiconducting barium titanate ceramics prepared by using yttrium hexaboride as sintering aid

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.X.; Chan, H.L.W.; Pang, G.K.H.; Choy, C.L

    2003-07-25

    Nb-doped BaTiO{sub 3} semiconducting ceramics have been prepared at 1150 deg. C by employing YB{sub 6} as the sintering aid. The low-temperature sintered samples exhibit a positive temperature coefficient of resistivity (PTCR) effect. The room-temperature resistivity and the magnitude of PTCR effect depend on the amount of YB{sub 6} added, the Nb{sub 2}O{sub 5} content and the sintering conditions. At 1 mol% of YB{sub 6}, the sample has a low room-temperature resistivity and a resistivity jump of about 10{sup 4}. Transmission electron microscope studies revealed that the intergranular region between the crystalline BaTiO{sub 3} grains has an amorphous structure. Y, Ba and Ti are present in the intergranular region but no Y is detectable in the crystalline grains. A liquid phase is believed to be present during sintering and it helps to facilitate the densification process and to enhance the PTCR effect.

  15. Energy transfer pathways in semiconducting carbon nanotubes revealed using two-dimensional white-light spectroscopy

    Science.gov (United States)

    Mehlenbacher, Randy D.; McDonough, Thomas J.; Grechko, Maksim; Wu, Meng-Yin; Arnold, Michael S.; Zanni, Martin T.

    2015-04-01

    Thin film networks of highly purified semiconducting carbon nanotubes (CNTs) are being explored for energy harvesting and optoelectronic devices because of their exceptional transport and optical properties. The nanotubes in these films are in close contact, which permits energy to flow through the films, although the pathways and mechanisms for energy transfer are largely unknown. Here we use a broadband continuum to collect femtosecond two-dimensional white-light spectra. The continuum spans 500 to 1,300 nm, resolving energy transfer between all combinations of bandgap (S1) and higher (S2) transitions. We observe ultrafast energy redistribution on the S2 states, non-Förster energy transfer on the S1 states and anti-correlated energy levels. The two-dimensional spectra reveal competing pathways for energy transfer, with S2 excitons taking routes depending on the bandgap separation, whereas S1 excitons relax independent of the bandgap. These observations provide a basis for understanding and ultimately controlling the photophysics of energy flow in CNT-based devices.

  16. Synthesis and characterization of organic semiconducting polymers containing dithienylfluorenone for use in organic photovoltaic cells.

    Science.gov (United States)

    Byun, Yun-Sun; Kim, Ji-Hoon; Park, Jong Baek; Hwang, Do-Hoon

    2014-08-01

    2,7-Bis(5-bromo-4-hexylthiophen-2-yl)-9H-fluoren-9-one (DTFO) was synthesized as a new electron-accepting material in semiconducting polymers for use in photovoltaic devices. The synthesized DTFO was polymerized with two different electron-donating counter monomers: 2,7-dibromo-9,9-dioctyl-9H-fluorene (DOF) and 2,6-bis(trimethyltin)-4,8-di(2-ethylhexyloxyl)benzo [1,2-b:4,5-b']dithiophene (BDT). Two alternating copolymers, poly(DTFO-alt-DOF) and poly(DTFO-alt-BDT), were synthesized through the Suzuki and Stille coupling polymerizations, respectively. The synthesized polymers exhibited good solubility in common solvents and show good thermal stability up to 350 °C. The optical band gap energies of poly(DTFO-alt-DOF) and poly(DTFO-alt-BDT) were determined to be 2.44 and 2.23 eV, respectively. The positions of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the polymers were determined by cyclic voltammetry (CV). One of these devices showed a power conversion efficiency of 0.50%, with an open-circuit voltage of 0.67 V, a short-circuit current of 2.34 mA/cm2, and a fill factor of 0.30 under air mass (AM) 1.5 global (1.5 G) illumination conditions (100 mW/cm2).

  17. Photoluminescence quenching of semiconducting polymer nanoparticles in presence of Au nanoparticles

    Indian Academy of Sciences (India)

    Santanu Bhattacharyya; Amitava Patra

    2012-10-01

    In this report, we have demonstrated the photoluminescence quenching and energy transfer properties of semiconducting polymer nanoparticles, poly (N-vinylcarbazole) (PVK) in presence of different sized Au nanoparticles by steady state and time-resolved spectroscopy. We have described the quenching phenomena by sphere of action static quenching mechanism and both dynamic and static quenching processes are found in these systems. PL quenching values are 24.22% and 57.3% for 14 nm and 18 nm Au nanoparticles, respectively. It is found that the radiative and nonradiative decay have been modified with the size of Au nanoparticles. PL quenching and shortening of decay time regarding polymer nanoparticles in presence of Au nanoparticles suggest the nonradiative energy transfer process. The values of energy transfer are 6.7%, 49.5% and 53.38% from PVK polymer nanoparticles to 3 nm, 14 nm and 18 nm Au nanoparticles, respectively. Using FRET and SET equations we have calculated the average distance of donor PVK polymer nanoparticles and acceptor Au nanoparticles.

  18. Structural studies of thin films of semiconducting nanoparticles in polymer matrices

    Energy Technology Data Exchange (ETDEWEB)

    Di Luccio, Tiziana [ENEA, Centro Ricerche Brindisi, SS7 Appia Km 706, I-72100 Brindisi (Italy)], E-mail: tiziana.diluccio@portici.enea.it; Piscopiello, Emanuela; Laera, Anna Maria [ENEA, Centro Ricerche Brindisi, SS7 Appia Km 706, I-72100 Brindisi (Italy); Antisari, Marco Vittori [ENEA, Centro Ricerche Casaccia, Via Anguillarese 301, I-00060 S. Maria di Galeria (Roma) (Italy)

    2007-09-15

    Ordered films of nanoscale materials are issue of wide interest for applications in several fields, such as optics, catalysis, and bioelectronics. In particular, semiconducting nanoparticles incorporation in a processable polymer film is an easy way to manipulate such materials for their application. We deposited thin layers of cadmium sulphide (CdS) and zinc sulphide (ZnS) nanoparticles embedded in a thermoplastic cyclo-olephin copolymer (COC) with elevated optical transparency and highly bio-compatible. The nanoparticles were obtained by thiolate precursors previously dispersed in the polymer upon thermal treatment at temperatures ranging between 200 and 300 deg. C depending on the desired size. The precursor/polymer solutions were spin-coated in order to get thin films. The spinning conditions were changed in order to optimise the layer thickness and uniformity. The samples were mainly characterised by X-ray reflectivity (XRR) and by high-resolution transmission electron microscopy (HRTEM) analyses. The thinnest layer we have deposited is 8 nm thick, as evaluated by XRR. The HRTEM measurements showed that the nanoparticles have quasi-spherical shape without evident microstructural defects. The size of the nanoparticles depends on the annealing temperature, e.g. at 232 deg. C the size of the CdS nanoparticles is about 4-5 nm.

  19. The patterning of sub-500 nm inorganic oxide and semiconducting polymeric structures

    Science.gov (United States)

    Hampton, Meredith J.; Williams, Stuart S.; Zhou, Zhilian; Nunes, Janine; Ko, Doo-Hyun; Templeton, Joseph L.; DeSimone, Joseph M.; Samulski, Edward T.

    2008-08-01

    The Pattern Replication In Non-wetting Templates (PRINT) technique has been extended to patterning of isolated features as well as embossed films of sub-500 nm "hard" inorganic oxides and nanocrystalline semiconductors and "soft" semiconducting polymers including TiO2, SnO2, ZnO, ITO, BaTiO3, CdSe, poly(3-hexylthiophene) (P3HT), Poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV), and other polythiophene derivatives. The low surface energy, chemically resistant, air permeable elastomeric perflouropolyether (PFPE) based molds allow for numerous materials to be patterned on a variety of substrates including glass, transparent conductive oxides, and thin films of conducting polymer for a wide range of electronic and optical applications. Additionally, PRINT has been employed to pattern features with aspect ratios greater than 1, deposit a second layer of features on top of an initial layer without pattern destruction, and replicate sub-100 nm sized features for photovoltaics applications. Materials and patterns generated in this work were characterized using a variety of techniques including: Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD).

  20. Fabrication and Characterisation of Polyaniline/Laponite based Semiconducting Organic/Inorganic Hybrid Material

    Directory of Open Access Journals (Sweden)

    Walt V.K. Wheelwright

    2014-05-01

    Full Text Available Novel organic-inorganic semiconducting hybrid material is developed by chemically grafting polyaniline (PANI onto an inorganic template, Laponite. The surface active silanol groups of the Laponite sheets were silylated with an aniline functionalised 3-phenylaminopropyltrimethoxysilane (PAPTMOS coupling agent followed by deposition of PANI onto the silylated surface. The method includes the reaction of Laponite with PAPTMOS dissolved in a very small amount of methanol at 110 °C for 44 h in a vacuum oven, interaction of the silylated product with PANI via in situ polymerisation of aniline and one-step isolation process by means of the removal of the non-connected PANI with N-methylpyrrolidinone-diethylamine binary solvent. After isolation and re-doping with methane sulfonic acid the Laponite-PAPTMOS-PANI hybrid becomes electrically conductive. The chemical attachment of PANI with silylated Laponite in the hybrids were characterised by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, and scanning electron microscopy.Defence Science Journal, Vol. 64, No. 3, May 2014, pp. 193-197, DOI:http://dx.doi.org/10.14429/dsj.64.7185

  1. Self-assembling semiconducting polymers--rods and gels from electronic materials.

    Science.gov (United States)

    Clark, Andrew P-Z; Shi, Chenjun; Ng, Benny C; Wilking, James N; Ayzner, Alexander L; Stieg, Adam Z; Schwartz, Benjamin J; Mason, Thomas G; Rubin, Yves; Tolbert, Sarah H

    2013-02-26

    In an effort to favor the formation of straight polymer chains without crystalline grain boundaries, we have synthesized an amphiphilic conjugated polyelectrolyte, poly(fluorene-alt-thiophene) (PFT), which self-assembles in aqueous solutions to form cylindrical micelles. In contrast to many diblock copolymer assemblies, the semiconducting backbone runs parallel, not perpendicular, to the long axis of the cylindrical micelle. Solution-phase micelle formation is observed by X-ray and visible light scattering. The micelles can be cast as thin films, and the cylindrical morphology is preserved in the solid state. The effects of self-assembly are also observed through spectral shifts in optical absorption and photoluminescence. Solutions of higher-molecular-weight PFT micelles form gel networks at sufficiently high aqueous concentrations. Rheological characterization of the PFT gels reveals solid-like behavior and strain hardening below the yield point, properties similar to those found in entangled gels formed from surfactant-based micelles. Finally, electrical measurements on diode test structures indicate that, despite a complete lack of crystallinity in these self-assembled polymers, they effectively conduct electricity.

  2. Passivity and Semiconducting Behavior of a High Nitrogen Stainless Steel in Acidic NaCl Solution

    Directory of Open Access Journals (Sweden)

    Yanxin Qiao

    2016-01-01

    Full Text Available The passivity and semiconducting behaviors of a high nitrogen-containing nickel-free stainless steel (HNSS in 0.05 mol/L H2SO4 + 0.5 mol/L NaCl have been investigated. Results indicated that HNSS offered excellent pitting corrosion resistance in corrosive environments. Three corrosion potential values were observed in potentiodynamic polarization response, indicating the existence of an unstable system. The current transient and Mott-Schottky plots demonstrated that the stability of passive films decreased with the increase of applied potentials. The angle resolved X-ray photoelectron spectrometric results revealed that the primary constituents of passive films formed in 0.05 mol/L H2SO4 + 0.5 mol/L NaCl solution were composed of iron oxides, manganese oxides, Cr2O3, and Cr(OH3. Meanwhile, it indicated that molybdenum oxides did not exist in the oxide layer, but chloride ions were present in the passive films.

  3. pH and Protein Sensing with Functionalized Semiconducting Oxide Nanobelt FETs

    Science.gov (United States)

    Cheng, Yi; Yun, C. S.; Strouse, G. F.; Xiong, P.; Yang, R. S.; Wang, Z. L.

    2008-03-01

    We report solution pH sensing and selective protein detection with high-performance channel-limited field-effect transistors (FETs) based on single semiconducting oxide (ZnO and SnO2) nanobelts^1. The devices were integrated with PDMS microfluidic channels for analyte delivery and the source/drain contacts were passivated for in-solution sensing. pH sensing experiments were performed on FETs with functionalized and unmodified nanobelts. Functionalization of the nanobelts by APTES was found to greatly improve the pH sensitivity. The change in nanobelt conductance as functions of pH values at different gate voltages and ionic strengths showed high sensitivity and consistency. For the protein detection, we achieved highly selective biotinylation of the nanobelt channel with through APTES linkage. The specific binding of fluorescently-tagged streptavidin to the biotinylated nanobelt was verified by fluorescence microscopy; non-specific binding to the substrate was largely eliminated using PEG-silane passivation. The electrical responses of the biotinylated FETs to the streptavidin binding in PBS buffers of different pH values were systematically measured. The results will be presented and discussed. ^1Y. Cheng et al., Appl. Phys. Lett. 89, 093114 (2006). *Supported by NSF NIRT Grant ECS-0210332.

  4. Electronic structure and magnetism in doped semiconducting half-Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, B R K; Dasgupta, I [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2005-08-24

    We have studied in detail the electronic structure and magnetism in M (Mn and Cr)-doped semiconducting half-Heusler compounds FeVSb, CoTiSb and NiTiSn (XY{sub x}M{sub 1-x}Z) in a wide concentration range using the local-spin density functional method in the framework of the tight-binding linearized muffin tin orbital method (TB-LMTO) and supercell approach. Our calculations indicate that some of these compounds are not only ferromagnetic but also half-metallic and may be useful for spintronics applications. The electronic structure of the doped systems is analysed with the aid of a simple model where we have considered the interaction between the dopant transition metal (M) and the valence band X-Z hybrid. We have shown that the strong X-d-M-d interaction places the M-d states close to the Fermi level with the M-t{sub 2g} states lying higher in energy in comparison to the M-e{sub g} states. Depending on the number of available d electrons, ferromagnetism is realized provided that the d manifold is partially occupied. The tendencies toward ferromagnetic (FM) or antiferromagnetic (AFM) behaviour are discussed within Anderson-Hasegawa models of super-exchange and double-exchange. In our calculations for Mn-doped NiTiSn, the strong preference for FM over AFM ordering suggests a possible high Curie temperature for these systems.

  5. Critical behavior of quasi-two-dimensional semiconducting ferromagnet Cr2Ge2Te6

    Science.gov (United States)

    Liu, Yu; Petrovic, C.

    2017-08-01

    The critical properties of the single-crystalline semiconducting ferromagnet Cr2Ge2Te6 were investigated by bulk dc magnetization around the paramagnetic to ferromagnetic phase transition. Critical exponents β =0.200 ±0.003 with a critical temperature Tc=62.65 ±0.07 K and γ =1.28 ±0.03 with Tc=62.75 ±0.06 K are obtained by the Kouvel-Fisher method whereas δ =7.96 ±0.01 is obtained by a critical isotherm analysis at Tc=62.7 K. These critical exponents obey the Widom scaling relation δ =1 +γ /β , indicating self-consistency of the obtained values. With these critical exponents the isotherm M (H ) curves below and above the critical temperatures collapse into two independent universal branches, obeying the single scaling equation m =f±(h ) , where m and h are renormalized magnetization and field, respectively. The determined exponents match well with those calculated from the results of the renormalization group approach for a two-dimensional Ising system coupled with a long-range interaction between spins decaying as J (r ) ≈r-(d +σ ) with σ =1.52 .

  6. Linear and Nonlinear Rheology Combined with Dielectric Spectroscopy of Hybrid Polymer Nanocomposites for Semiconductive Applications.

    Science.gov (United States)

    Kádár, Roland; Abbasi, Mahdi; Figuli, Roxana; Rigdahl, Mikael; Wilhelm, Manfred

    2017-01-24

    The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate) (EBA) nanocomposite hybrids containing graphite nanoplatelets (GnP) and carbon black (CB). The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests.

  7. Charge transport in amorphous and tetragonal semiconducting YBaCuO films

    Science.gov (United States)

    Çelik-Butler, Z.; Shan, P. C.; Butler, D. P.; Jahanzeb, A.; Travers, C. M.; Kula, W.; Sobolewski, R.

    1997-06-01

    We have explored the charge transport mechanisms in six different YBaCuO semiconducting thin films in the temperature range of 70 K to room temperature. Two of the samples were deposited on LaAlO 3 substrate and were tetragonal with the composition of YBa 2Cu 3O 6.5 and YBa 2Cu 3O 6.3. The other four were amorphous as-deposited on Si substrate with and without a MgO buffer layer, and on an oxidized Si substrate with and without a MgO buffer layer. All tested films exhibited semiconductor-type resistance vs. temperature characteristics with increasing resistance as the temperature was decreased. Around room temperature all six samples had thermally activated transport characteristics that was interpreted as activation of hole-like carriers from localized states around the Fermi level to extended states. As the temperature was decreased, two tetragonal samples went through a transition to a variable range hopping-like conduction. The amorphous ones remained within the thermally-activated transport regime in the temperature range of 253 K to 318 K, with EA ≈ 0.2 eV.

  8. Biotin-functionalized semiconducting polymer in an organic field effect transistor and application as a biosensor.

    Science.gov (United States)

    Kim, Zin-Sig; Lim, Sang Chul; Kim, Seong Hyun; Yang, Yong Suk; Hwang, Do-Hoon

    2012-01-01

    This report presents biotin-functionalized semiconducting polymers that are based on fluorene and bithiophene co-polymers (F8T2). Also presented is the application of these polymers to an organic thin film transistor used as a biosensor. The side chains of fluorene were partially biotinylated after the esterification of the biotin with corresponding alcohol-groups at the side chain in F8T2. Their properties as an organic semiconductor were tested using an organic thin film transistor (OTFT) and were found to show typical p-type semiconductor curves. The functionality of this biosensor in the sensing of biologically active molecules such as avidin in comparison with bovine serum albumin (BSA) was established through a selective decrease in the conductivity of the transistor, as measured with a device that was developed by the authors. Changes to the optical properties of this polymer were also measured through the change in the color of the UV-fluorescence before and after a reaction with avidin or BSA.

  9. Biotin-Functionalized Semiconducting Polymer in an Organic Field Effect Transistor and Application as a Biosensor

    Directory of Open Access Journals (Sweden)

    Yong Suk Yang

    2012-08-01

    Full Text Available This report presents biotin-functionalized semiconducting polymers that are based on fluorene and bithiophene co-polymers (F8T2. Also presented is the application of these polymers to an organic thin film transistor used as a biosensor. The side chains of fluorene were partially biotinylated after the esterification of the biotin with corresponding alcohol-groups at the side chain in F8T2. Their properties as an organic semiconductor were tested using an organic thin film transistor (OTFT and were found to show typical p-type semiconductor curves. The functionality of this biosensor in the sensing of biologically active molecules such as avidin in comparison with bovine serum albumin (BSA was established through a selective decrease in the conductivity of the transistor, as measured with a device that was developed by the authors. Changes to the optical properties of this polymer were also measured through the change in the color of the UV-fluorescence before and after a reaction with avidin or BSA.

  10. Photoluminescence and semiconducting behavior of Fe, Co, Ni and Cu implanted in heavy metal oxide glasses

    Directory of Open Access Journals (Sweden)

    Mohamed A. Marzouk

    2016-07-01

    Full Text Available Transition metal ions (0.5 wt% of Fe2O3, CoO, NiO or CuO doped heavy metal oxide glasses having chemical composition of 60PbO·20Bi2O3·20 MxOy mol% (where MxOy = B2O3 or SiO2 or P2O5 were prepared by conventional melt annealing method. Combined optical and photoluminescence properties have been measured and employed to evaluate the prepared glassy samples. From the absorption edge data, the values of the optical band gap Eopt, Urbach energy (ΔE and refractive index were calculated to estimate semiconducting behavior. Photoluminescence and values of the optical energy gap were found to be dependent on the glass composition. The variations of the photoluminescence intensity, values of optical band gap, Urbach energy and refractive index gave an indication to use the prepared glasses for design of novel functional optical materials with higher optical performance.

  11. Field-induced detrapping in disordered organic semiconducting host-guest systems

    Science.gov (United States)

    Cottaar, J.; Coehoorn, R.; Bobbert, P. A.

    2010-11-01

    In a disordered organic semiconducting host-guest material, containing a relatively small concentration of guest molecules acting as traps, the charge transport may be viewed as resulting from carriers that are detrapped from the guest to the host. Commonly used theories include only detrapping due to thermal excitation, described by the Fermi-Dirac (FD) distribution function. In this paper, we develop a theory describing the effect of field-induced detrapping (FID), which provides an additional contribution at finite electric fields. It is found from three-dimensional simulations that the FID effect can be described by a field-dependent generalized FD distribution that depends only on the shape of the host density of states (DOS) and not on the guest DOS. For the specific case of a Gaussian host DOS, we give an accurate and easy-to-use analytical expression for this distribution. The application of our theory is demonstrated for sandwich-type devices under conditions typical of organic light-emitting diodes.

  12. Purification of semiconducting single-walled carbon nanotubes by spiral counter-current chromatography.

    Science.gov (United States)

    Knight, Martha; Lazo-Portugal, Rodrigo; Ahn, Saeyoung Nate; Stefansson, Steingrimur

    2017-02-03

    Over the last decade man-made carbon nanostructures have shown great promise in electronic applications, but they are produced as very heterogeneous mixtures with different properties so the achievement of a significant commercial application has been elusive. The dimensions of single-wall carbon nanotubes are generally a nanometer wide, up to hundreds of microns long and the carbon nanotubes have anisotropic structures. They are processed to have shorter lengths but they need to be sorted by diameter and chirality. Thus counter-current chromatography methods developed for large molecules are applied to separate these compounds. A modified mixer-settler spiral CCC rotor made with 3 D printed disks was used with a polyethylene glycol-dextran 2-phase solvent system and a surfactant gradient to purify the major species in a commercial preparation. We isolated the semi-conducting single walled carbon nanotube chiral species identified by UV spectral analysis. The further development of spiral counter-current chromatography instrumentation and methods will enable the scalable purification of carbon nanotubes useful for the next generation electronics.

  13. Singlet-Oxygen Generation From Individual Semiconducting and Metallic Nanostructures During Near-Infrared Laser Trapping

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Bennett E.; Roder, Paden B.; Hanson, Jennifer L.; Manandhar, Sandeep; Devaraj, Arun; Perea, Daniel E.; Kim, Woo-Joong; Kilcoyne, Arthur L.; Pauzauskie, Peter J.

    2015-03-13

    Photodynamic therapy has been used for several decades in the treatment of solid tumors through the generation of reactive singlet-oxygen species (1O2). Recently, nanoscale metallic and semiconducting materials have been reported to act as photosensitizing agents with additional diagnostic and therapeutic functionality. To date there have been no reports of observing the generation of singlet-oxygen at the level of single nanostructures, particularly at near infrared (NIR) wavelengths. Here we demonstrate that NIR laser-tweezers can be used to observe the formation of singlet-oxygen produced from individual silicon and gold nanowires via use of a commercially available reporting dye. The laser trap also induces 2-photon photoexcitation of the dye following a chemical reaction with singlet oxygen. Corresponding 2-photon emission spectra confirms the generation of singlet oxygen from individual silicon nanowires at room temperature (30°C), suggesting a range of applications in understanding the impact of 1O2 on individual cancer cells.

  14. Variable range hopping conduction and microstructure properties of semiconducting Co-doped TiO 2

    Science.gov (United States)

    Okutan, Mustafa; Bakan, Halil I.; Korkmaz, Kemal; Yakuphanoglu, Fahrettin

    2005-01-01

    The surface morphology, phases existing in the microstructure and conductivity behavior of Co-doped TiO2 have been investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), electrical conductivity measurements and X-ray diffraction technique. The semiconducting phase is found to obey Mott's variable range hopping mechanism of the conduction. The conduction mechanism of the ceramic shows a crossover from the, exp[-(T0/T)] law to a simply activated law, exp(-ΔE/kT). This behavior is attributed to temperature-induced transition from 3D to thermally activated behavior. The hopping conduction parameters such as the characteristic temperature ( T0), localization length ( α), hopping distance ( R), activation energy ( ΔE) and density of states at Fermi level (N(EF) have been calculated. Surface morphology shows that the ceramic has a regular surface. The SEM study indicates that there are grains which have a certain type in the microstructure. Rutile phases with different plane in microstructure were found.

  15. IMPORTANT NOTIFICATION

    CERN Multimedia

    HR Department

    2009-01-01

    Green plates, removals and importation of personal effects Please note that, as from 1 April 2009, formalities relating to K and CD special series French vehicle plates (green plates), removals and importation of personal effects into France and Switzerland will be dealt with by GS Department (Building 73/3-014, tel. 73683/74407). Importation and purchase of tax-free vehicles in Switzerland, as well as diplomatic privileges, will continue to be dealt with by the Installation Service of HR Department (Building 33/1-011, tel. 73962). HR and GS Departments

  16. Cost effectiveness of a pharmacist-led information technology intervention for reducing rates of clinically important errors in medicines management in general practices (PINCER).

    Science.gov (United States)

    Elliott, Rachel A; Putman, Koen D; Franklin, Matthew; Annemans, Lieven; Verhaeghe, Nick; Eden, Martin; Hayre, Jasdeep; Rodgers, Sarah; Sheikh, Aziz; Avery, Anthony J

    2014-06-01

    We recently showed that a pharmacist-led information technology-based intervention (PINCER) was significantly more effective in reducing medication errors in general practices than providing simple feedback on errors, with cost per error avoided at £79 (US$131). We aimed to estimate cost effectiveness of the PINCER intervention by combining effectiveness in error reduction and intervention costs with the effect of the individual errors on patient outcomes and healthcare costs, to estimate the effect on costs and QALYs. We developed Markov models for each of six medication errors targeted by PINCER. Clinical event probability, treatment pathway, resource use and costs were extracted from literature and costing tariffs. A composite probabilistic model combined patient-level error models with practice-level error rates and intervention costs from the trial. Cost per extra QALY and cost-effectiveness acceptability curves were generated from the perspective of NHS England, with a 5-year time horizon. The PINCER intervention generated £2,679 less cost and 0.81 more QALYs per practice [incremental cost-effectiveness ratio (ICER): -£3,037 per QALY] in the deterministic analysis. In the probabilistic analysis, PINCER generated 0.001 extra QALYs per practice compared with simple feedback, at £4.20 less per practice. Despite this extremely small set of differences in costs and outcomes, PINCER dominated simple feedback with a mean ICER of -£3,936 (standard error £2,970). At a ceiling 'willingness-to-pay' of £20,000/QALY, PINCER reaches 59 % probability of being cost effective. PINCER produced marginal health gain at slightly reduced overall cost. Results are uncertain due to the poor quality of data to inform the effect of avoiding errors.

  17. Importance of energy efficiency in the design of the Process and Environmental Technology Laboratory (PETL) at Sandia National Laboratories, New Mexico (NM)

    Energy Technology Data Exchange (ETDEWEB)

    Wrons, R.

    1998-06-01

    As part of the design of the Process and Environmental Technology Laboratory (PETL) in FY97, an energy conservation report (ECR) was completed. The original energy baseline for the building, established in Title 1 design, was 595,000 BTU/sq. ft./yr, site energy use. Following the input of several reviewers and the incorporation of the various recommendations into the Title 2 design, the projected energy consumption was reduced to 341,000 BTU/sq. ft./yr. Of this reduction, it is estimated that about 150,000 BTU/sq. ft./yr resulted from inclusion of more energy efficient options into the design. The remaining reductions resulted from better accounting of energy consumption between Title 1 ECR and the final ECR. The energy efficient features selected by the outcome of the ECR were: (1) Energy Recovery system, with evaporative cooling assist, for the Exhaust/Make-up Air System; (2) Chilled Water Thermal Storage system; (3) Premium efficiency motors for large, year-round applications; (4) Variable frequency drives for all air handling fan motors; (4) Premium efficiency multiple boiler system; and (5) Lighting control system. The annual energy cost savings due to these measures will be about $165,000. The estimated annual energy savings are two million kWhrs electric, and 168,000 therms natural gas, the total of which is equivalent to 23,000 million BTUs per year. Put into the perspective of a typical office/light lab at SNL/NM, the annual energy savings is equal the consumption of a 125,000 square foot building. The reduced air emissions are approximately 2,500 tons annually.

  18. Identifying most important skills for PhD students in Food Science and Technology: a comparison between industry and academic stakeholders

    Directory of Open Access Journals (Sweden)

    Chelo González-Martínez

    2015-10-01

    Full Text Available Nowadays, there is an increasing need of new skills for PhD students to face the future labour market prospects. PhD graduates must have qualities attractive not only in academia but also outside, in both manufacture and service-oriented enterprises, in small innovative companies, and in the civil services and public administration, among others. To know what the needs of these future employees are, is of great importance to be able to improve their personal and academic formation. The aim of this work was, in the framework of the EC-funded ISEKI_Food 4 network, to evaluate the most desirable specific and soft skills that PhD students should acquire by the end of their doctoral studies. To this aim, several surveys were conducted and sent to the different stakeholders (academia and food industry partners in order to collect the information needed. Results showed that competences related to research skills and techniques, research management, personal effectiveness and communication skills were considered to be the most valuable skills to be acquired by our PhD students to meet the future needs of the labour market.  The importance of these skills was appreciated differently, depending on the stakeholder. To sum up, some recommendations to integrate such valuable skills into the curricula of the PhD student are given.

  19. Charge and excitation dynamics in semiconducting polymer layers doped with emitters and charge carrier traps; Ladungstraeger- und Anregungsdynamik in halbleitenden Polymerschichten mit eingemischten Emittern und Ladungstraegerfallen

    Energy Technology Data Exchange (ETDEWEB)

    Jaiser, F.

    2006-06-15

    Light-emitting diodes generate light from the recombination of injected charge carriers. This can be obtained in inorganic materials. Here, it is necessary to produce highly ordered crystalline structures that determine the properties of the device. Another possibility is the utilization of organic molecules and polymers. Based on the versatile organic chemistry, it is possible to tune the properties of the semiconducting polymers already during synthesis. In addition, semiconducting polymers are mechanically flexible. Thus, it is possible to construct flexible, large-area light sources and displays. The first light-emitting diode using a polymer emitter was presented in 1990. Since then, this field of research has grown rapidly up to the point where first products are commercially available. It has become clear that the properties of polymer light-emitting diodes such as color and efficiency can be improved by incorporating multiple components inside the active layer. At the same time, this gives rise to new interactions between these components. While components are often added either to improve the charge transport or to change the emission, it has to made sure that other processes are not influenced in a negative manner. This work investigates some of these interactions and describes them with simple physical models. First, blue light-emitting diodes based on polyfluorene are analyzed. This polymer is an efficient emitter, but it is susceptible to the formation of chemical defects that can not be suppressed completely. These defects form electron traps, but their effect can be compensated by the addition of hole traps. The underlying process, namely the changed charge carrier balance, is explained. In the following, blend systems with dendronized emitters that form electron traps are investigated. The different influence of the insulating shell on the charge and energy transfer between polymer host and the emissive core of the dendrimers is examined. In the

  20. Photocatalytic generation of dissolved oxygen and oxyhemoglobin in whole blood based on the indirect interaction of ultraviolet light with a semiconducting titanium dioxide thin film

    Science.gov (United States)

    Gilbert, Richard J.; Carleton, Linda M.; Dasse, Kurt A.; Martin, Peter M.; Williford, Ralph E.; Monzyk, Bruce F.

    2007-10-01

    Most current artificial lung technologies require the delivery of oxygen to the blood via permeable hollow fibers, depending on membrane diffusivity and differential partial pressure to drive gas exchange. We have identified an alternative approach in which dissolved oxygen (DO) is generated directly from the water content of blood through the indirect interaction of ultraviolet (UV) light with a semiconducting titanium dioxide thin film. This reaction is promoted by photon absorption and displacement of electrons from the photoactive film and yields a cascading displacement of electron "holes" to the aqueous interface resulting in the oxidation of water molecules to form DO. Anatase TiO2 (photocatalyst) and indium tin oxide (ITO) (electrically conductive and light transparent) coatings were deposited onto quartz flow-cell plates by direct current reactive magnetron sputtering. The crystal structure of the films was evaluated by grazing incidence x-ray diffraction, which confirmed that the primary crystal phase of the TiO2 thin film was anatase with a probable rutile secondary phase. Surface topology and roughness were determined by atomic force microscopy, demonstrating a stochastically uniform array of nanocrystallites. UV illumination of the titanium dioxide thin film through the quartz/ITO surface resulted in the rapid increase of DO and oxyhemoglobin in adjacent flowing blood on the opposite TiO2 surface at a rate of 1.0×10-5 mmol O2/s. The rate of oxyhemoglobin generation was linearly proportional to residence time adjacent to the photoactive surface in a flow-through test cell under steady-state conditions. Preliminary biocompatibility for the proposed photocatalytic effect on whole blood demonstrated no increase in the rate of hemolysis or generation of toxic byproducts of photo-oxidation. These results demonstrate the feasibility and safety of employing optoelectronic mechanisms to promote oxygenation of hemoglobin in whole blood and provide

  1. Management of Subarachnoid Hemorrhage in Two Important Italian Political Leaders: A Paradigm of Ethical and Technological Evolution of Neurosurgery During the Past Half-Century.

    Science.gov (United States)

    Longatti, Pierluigi; Giombelli, Ermanno; Pavesi, Giacomo; Carteri, Alessandro; Feletti, Alberto

    2016-08-01

    For a curious and extraordinary coincidence, 5 of the 7 most relevant leaders of the Italian Communist Party (Partito Comunista Italiano, which was established in 1921, has been the biggest Communist Party in Western Countries) suffered a cerebral stroke. Cerebrovascular diseases afflicted also Stalin and Lenin, and a number of Presidents of the United States. We present the stories of 2 important Italian political leaders who shared both the leadership role of the major left Italian Party and the dramatic experience of a subarachnoid hemorrhage. Retracing their medical incidents, separated by 50 years of history, we show how a fatal medical disease has become neurosurgical and successfully cured thanks to the advances of neurosurgery, neuroradiology, and hospital organization. A neurologic disease that was disgraceful 50 years ago has lost any disquieting and embarrassing significance in the present time to the light of evolution of vascular neurosurgery.

  2. Pure Optical Dephasing Dynamics in Semiconducting Single-Walled Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Matt [University of California, Berkeley; Fleming, Graham [University of California, Berkeley; Ma, Yingzhong [ORNL; Green, Alexander A. [Northwestern University, Evanston; Hersam, Mark C. [Northwestern University, Evanston

    2011-01-01

    We report a detailed study of ultrafast exciton dephasing processes in semiconducting single-walled carbon nanotubes (SWNTs) employing a sample highly enriched in a single tube species, the (6,5) tube. Systematic measurements of femtosecond pump-probe, two-pulse photon echo and three-pulse photon echo peak shift over a broad range of excitation intensities and lattice temperature (from 4.4 to 292 K) enable us to quantify the timescales of pure optical dephasing (T 2 ), along with exciton-exciton and exciton-phonon scattering, environmental effects as well as spectral diffusion. While the exciton dephasing time (T2 ) increases from 205 fs at room temperature to 320 fs at 70 K, we found that further decrease of the lattice temperature leads to a shortening of the T2 times. This complex temperature dependence was found to arise from an enhanced relaxation of exciton population at lattice temperatures below 80 K. By quantitatively accounting the contribution from the population relaxation, the corresponding pure optical dephasing times increase monotonically from 225 fs at room temperature to 508 fs at 4.4 K. We further found that below 180 K, the inverse of the pure dephasing time (1/T 2 ) scales linearly with temperature with a slope of 6.7 0.6 eV/K, which suggests dephasing arising from one-phonon scattering (i.e. acoustic phonons). In view ofthe large dynamic disorder of the surrounding environment, the origin of the long room temperature pure dephasing time is proposed to result from reduced strength of exciton-phonon coupling by motional narrowing over nuclear fluctuations. This consideration further suggests the occurrence of remarkable initial exciton delocalization, and makes nanotubes ideal to study many-body effects in spatially confined systems.

  3. High-performance nonvolatile organic transistor memory devices using the electrets of semiconducting blends.

    Science.gov (United States)

    Chiu, Yu-Cheng; Chen, Tzu-Ying; Chen, Yougen; Satoh, Toshifumi; Kakuchi, Toyoji; Chen, Wen-Chang

    2014-08-13

    Organic nonvolatile transistor memory devices of the n-type semiconductor N,N'-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI) were prepared using various electrets (i.e., three-armed star-shaped poly[4-(diphenylamino)benzyl methacrylate] (N(PTPMA)3) and its blends with 6,6-phenyl-C61-butyric acid methyl ester (PCBM), 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pen) or ferrocene). In the device using the PCBM:N(PTPMA)3 blend electret, it changed its memory feature from a write-once-read-many (WORM) type to a flash type as the PCBM content increased and could be operated repeatedly based on a tunneling process. The large shifts on the reversible transfer curves and the hysteresis after implementing a gate bias indicated the considerable charge storage in the electret layer. On the other hand, the memory characteristics showed a flash type and a WORM characteristic, respectively, using the donor/donor electrets TIPS-pen:N(PTPMA)3 and ferrocene:N(PTPMA)3. The variation on the memory characteristics was attributed to the difference of energy barrier at the interface when different types of electret materials were employed. All the studied memory devices exhibited a long retention over 10(4) s with a highly stable read-out current. In addition, the afore-discussed memory devices by inserting another electret layer of poly(methacrylic acid) (PMAA) between the BPE-PTCDI layer and the semiconducting blend layer enhanced the write-read-erase-read (WRER) operation cycle as high as 200 times. This study suggested that the energy level and charge transfer in the blend electret had a significant effect on tuning the characteristics of nonvolatile transistor memory devices.

  4. Linear and Nonlinear Rheology Combined with Dielectric Spectroscopy of Hybrid Polymer Nanocomposites for Semiconductive Applications

    Directory of Open Access Journals (Sweden)

    Roland Kádár

    2017-01-01

    Full Text Available The linear and nonlinear oscillatory shear, extensional and combined rheology-dielectric spectroscopy of hybrid polymer nanocomposites for semiconductive applications were investigated in this study. The main focus was the influence of processing conditions on percolated poly(ethylene-butyl acrylate (EBA nanocomposite hybrids containing graphite nanoplatelets (GnP and carbon black (CB. The rheological response of the samples was interpreted in terms of dispersion properties, filler distortion from processing, filler percolation, as well as the filler orientation and distribution dynamics inside the matrix. Evidence of the influence of dispersion properties was found in linear viscoelastic dynamic frequency sweeps, while the percolation of the nanocomposites was detected in nonlinearities developed in dynamic strain sweeps. Using extensional rheology, hybrid samples with better dispersion properties lead to a more pronounced strain hardening behavior, while samples with a higher volume percentage of fillers caused a drastic reduction in strain hardening. The rheo-dielectric time-dependent response showed that in the case of nanocomposites containing only GnP, the orientation dynamics leads to non-conductive samples. However, in the case of hybrids, the orientation of the GnP could be offset by the dispersing of the CB to bridge the nanoplatelets. The results were interpreted in the framework of a dual PE-BA model, where the fillers would be concentrated mainly in the BA regions. Furthermore, better dispersed hybrids obtained using mixing screws at the expense of filler distortion via extrusion processing history were emphasized through the rheo-dielectric tests.

  5. Diameter-Specific Growth of Semiconducting SWNT Arrays Using Uniform Mo2C Solid Catalyst.

    Science.gov (United States)

    Zhang, Shuchen; Tong, Lianming; Hu, Yue; Kang, Lixing; Zhang, Jin

    2015-07-22

    Semiconducting single-walled nanotube (s-SWNT) arrays with specific diameters are urgently demanded in the applications in nanoelectronic devices. Herein, we reported that by using uniform Mo2C solid catalyst, aligned s-SWNT (∼90%) arrays with narrow-diameter distribution (∼85% between 1.0 and 1.3 nm) on quartz substrate can be obtained. Mo2C nanoparticles with monodisperse sizes were prepared by using molybdenum oxide-based giant clusters, (NH4)42[Mo132O372(H3CCOO)30(H2O)72]·10H3CCOONH4·300H2O(Mo132), as the precursor that was carburized by a gas mixture of C2H5OH/H2 during a temperature-programmed reduction. In this approach, the formation of volatile MoO3 was inhibited due to the annealing and reduction at a low temperature. As a result, uniform Mo2C nanoparticles are formed, and their narrow size-dispersion strictly determines the diameter distribution of SWNTs. During the growth process, Mo2C selectively catalyzes the scission of C-O bonds of ethanol molecules, and the resultant absorbed oxygen (Oads) preferentially etches metallic SWNTs (m-SWNTs), leading to the high-yield of s-SWNTs. Raman spectroscopic analysis showed that most of the s-SWNTs can be identified as (14, 4), (13, 6), or (10, 9) tubes. Our findings open up the possibility of the chirality-controlled growth of aligned-SWNTs using uniform carbide nanoparticles as solid catalysts for practical nanoelectronics applications.

  6. Electro-Thermal and Semiconductivity Behaviour of Natural Sintered Complex Carbonate Ore for Thermo-Technological Applications

    OpenAIRE

    Loutfy H. Madkour

    2014-01-01

    The polymetal (Zn, Pb, Fe, Ca, Mg, Cd, Ba, Ni, Ti, and SiO2) complex Umm-Gheig carbonate ore is subjected to sintering treatment at 573, 773, 973 and 1273 K respectively for four hours. Chemical, spectral, X-ray and differential thermal analyses are applied for the native ore as well as for the samples preheated and sintered. The current versus applied DC voltage (I–V) characteristics, bulk density (Db), percent shrinkage (%S), activation energy (Ea) and energy gap (Eg) are established for th...

  7. Soulful Technologies

    DEFF Research Database (Denmark)

    Fausing, Bent

    2010-01-01

    or anthropomorphism is important for the branding of new technology. Technology is seen as creating a techno-transcendence towards a more qualified humanity which is in contact with fundamental human values like intuition, vision, and sensing; all the qualities that technology, industrialization, and rationalization...

  8. High electron mobility and quantum oscillations in non-encapsulated ultrathin semiconducting Bi2O2Se

    Science.gov (United States)

    Wu, Jinxiong; Yuan, Hongtao; Meng, Mengmeng; Chen, Cheng; Sun, Yan; Chen, Zhuoyu; Dang, Wenhui; Tan, Congwei; Liu, Yujing; Yin, Jianbo; Zhou, Yubing; Huang, Shaoyun; Xu, H. Q.; Cui, Yi; Hwang, Harold Y.; Liu, Zhongfan; Chen, Yulin; Yan, Binghai; Peng, Hailin

    2017-07-01

    High-mobility semiconducting ultrathin films form the basis of modern electronics, and may lead to the scalable fabrication of highly performing devices. Because the ultrathin limit cannot be reached for traditional semiconductors, identifying new two-dimensional materials with both high carrier mobility and a large electronic bandgap is a pivotal goal of fundamental research. However, air-stable ultrathin semiconducting materials with superior performances remain elusive at present. Here, we report ultrathin films of non-encapsulated layered Bi2O2Se, grown by chemical vapour deposition, which demonstrate excellent air stability and high-mobility semiconducting behaviour. We observe bandgap values of ˜0.8 eV, which are strongly dependent on the film thickness due to quantum-confinement effects. An ultrahigh Hall mobility value of >20,000 cm2 V-1 s-1 is measured in as-grown Bi2O2Se nanoflakes at low temperatures. This value is comparable to what is observed in graphene grown by chemical vapour deposition and at the LaAlO3-SrTiO3 interface, making the detection of Shubnikov-de Haas quantum oscillations possible. Top-gated field-effect transistors based on Bi2O2Se crystals down to the bilayer limit exhibit high Hall mobility values (up to 450 cm2 V-1 s-1), large current on/off ratios (>106) and near-ideal subthreshold swing values (˜65 mV dec-1) at room temperature. Our results make Bi2O2Se a promising candidate for future high-speed and low-power electronic applications.

  9. Communication: electronic band gaps of semiconducting zig-zag carbon nanotubes from many-body perturbation theory calculations.

    Science.gov (United States)

    Umari, P; Petrenko, O; Taioli, S; De Souza, M M

    2012-05-14

    Electronic band gaps for optically allowed transitions are calculated for a series of semiconducting single-walled zig-zag carbon nanotubes of increasing diameter within the many-body perturbation theory GW method. The dependence of the evaluated gaps with respect to tube diameters is then compared with those found from previous experimental data for optical gaps combined with theoretical estimations of exciton binding energies. We find that our GW gaps confirm the behavior inferred from experiment. The relationship between the electronic gap and the diameter extrapolated from the GW values is also in excellent agreement with a direct measurement recently performed through scanning tunneling spectroscopy.

  10. Inkjet printed polymer light-emitting devices fabricated by thermal embedding of semiconducting polymer nanospheres in an inert matrix

    Science.gov (United States)

    Fisslthaler, Evelin; Sax, Stefan; Scherf, Ullrich; Mauthner, Gernot; Moderegger, Erik; Landfester, Katharina; List, Emil J. W.

    2008-05-01

    An aqueous dispersion of semiconducting polymer nanospheres was used to fabricate polymer light-emitting devices by inkjet printing in an easy-to-apply process with a minimum feature size of 20μm. To form the devices, the electroluminescent material was printed on a nonemitting polystyrene matrix layer and embedded by thermal annealing. The process allows the printing of light-emitting thin-film devices without extensive optimization of film homogeneity and thickness of the active layer. Optical micrographs of printed device arrays, electroluminescence emission spectra, and I /V characteristics of printed ITO/PEDOT:PSS/PS/SPN/Al devices are presented.

  11. Lowest-order corrections to the RPA polarizability and GW self-energy of a semiconducting wire

    Science.gov (United States)

    de Groot, H. J.; Ummels, R. T. M.; Bobbert, P. A.; van Haeringen, W.

    1996-07-01

    We present the results of the addition of lowest-order vertex and self-consistency corrections to the RPA polarizability and the GW self-energy for a semiconducting wire. It is found that, when starting from a local density approximation zeroth-order Green function and systematically including these corrections in both the polarizability and the self-energy, the correction to the non-self-consistent RPA-GW band gap is small. Partial inclusion of these corrections leads to very different band gaps. This sheds new light on the puzzling question why non-self-consistent RPA-GW calculations of band gaps have been so very successful.

  12. [Imported histoplasmosis].

    Science.gov (United States)

    Stete, Katarina; Kern, Winfried V; Rieg, Siegbert; Serr, Annerose; Maurer, Christian; Tintelnot, Kathrin; Wagner, Dirk

    2015-06-01

    Infections with Histoplasma capsulatum are rare in Germany, and mostly imported from endemic areas. Infections can present as localized or disseminated diseases in immunocompromised as well as immunocompetent hosts. A travel history may be a major clue for diagnosing histoplasmosis. Diagnostic tools include histology, cultural and molecular detection as well as serology. Here we present four cases of patients diagnosed and treated in Freiburg between 2004 and 2013 that demonstrate the broad range of clinical manifestations of histoplasmosis: an immunocompetent patient with chronic basal meningitis; a patient with HIV infection and fatal disseminated disease; a patient with pulmonary and cutaneous disease and mediastinal and cervical lymphadenopathy; and an immunosuppressed patient with disseminated involvement of lung, bone marrow and adrenal glands.

  13. 我国农业技术引进中政府行为优化对策研究%Study on the Countermeasures of the Optimization of the Governmental Behavior of Agricultural Technology Import in China

    Institute of Scientific and Technical Information of China (English)

    李奋生; 李娜

    2015-01-01

    Based on the analysis of the existing problems of government behavior in the introduction of our country’s agri-cultural technology and the lessons of Japan,India and Brazil and other countries'experience,we should put forword some countermeasures to regulate the government behavior in the introduction of our country’s agricultural technology:to promote the legislation of introduction of agricultural technology;to improve the relevant laws and regulations;to increase the inten-sity of macroeconomic regulation and control from the government angle;to revise relevant product catalogues timely;to op-timize the structure of agriculture technology introduction;to pay attention to the digestion,absorption and innovation after the introduction;to attach importance to the follow -up research and extension;to adhere to the combination of “bringing in ”and “going out”;to strengthen the efforts to import agriculture technology talents of high levels;to strengthen the agri-culture technology publicity and education to farmers.%在分析我国农业技术引进中政府行为现存问题以及借鉴日本、印度和巴西等国家经验的基础上,提出推动农业技术引进立法,完善相关法规,政府加大宏观调控的力度,及时修订相关产品目录,不断优化农业技术引进的结构,注重引进后的消化、吸收和创新,重视后续研究和推广,坚持“引进来”和“走出去”相结合,进一步加大高层次农业技术人才的引进力度,加强对农民进行农业技术宣传和教育等对策,规范我国农业技术引进中的政府行为。

  14. Ciência, Tecnologia e Sociedade: a relevância do enfoque CTS para o contexto do Ensino Médio Science, Technology and Society: the importance of the STS view to high school context

    Directory of Open Access Journals (Sweden)

    Nilcéia Aparecida Maciel Pinheiro

    2007-04-01

    Full Text Available Ressalta-se a importância do enfoque Ciência, Tecnologia e Sociedade (CTS perante os questionamentos críticos e reflexivos acerca do contexto científico-tecnológico e social e, em especial, sua relevância para o Ensino Médio. Os pressupostos do movimento CTS têm se ampliado em toda sociedade brasileira, principalmente na área educacional. Dentro da proposta da Lei de Diretrizes e Bases da Educação Nacional (LDB, configurada nos Parâmetros Curriculares Nacionais do Ensino Médio (PCNEMs, percebe-se a relevância de aproximar o aluno da interação com a ciência e a tecnologia em todas as dimensões da sociedade, oportunizando a ele uma concepção ampla e social do contexto científico-tecnológico.We aim to highlight the importance of the STS view as a driving force of critical and reflexive questions about scientific, technological and social contexts, and also, to emphasize its relevance to High School. The STS movement has spread throughout our society and, specially, has gained more and more followers in the educational area. Inside the Guidelines Law of the National Education (LDB proposal, designed in the National Curriculum Parameters for Secondary Education (PCNEMS, we noticed the importance of bringing the student closer to the interaction between science and technology in societal dimensions, considering their reciprocal relation, giving the students a wide and social conception of the scientific and technological context.

  15. Semiconducting and dielectric properties of barium titanates, tantalates and niobates with perovskite structure

    Science.gov (United States)

    Kolodiazhnyi, Taras

    The dielectric and semiconducting properties of two types of ceramics (n-type BaTiO3 and dielectric Ba(B'1/3 B″2/3)O3 where B' = Mg, Zn, Ni, and B″ = Nb, Ta) were characterized. Complex impedance analysis and dc conductivity measurements of samples prepared at various PO2 have ruled out oxygen chemisorption in favor of interfacial segregation of cation vacancies as the cause of the positive temperature coefficient of resistivity (PTCR) effect in n-type BaTiO3. The effect of preparation conditions, sintering atmosphere, stoichiometry, and post-sinter anneal on the defect chemistry of BaTiO3 was studied using the electron paramagnetic resonance (EPR) technique. Several paramagnetic defects such as, Ti3+, VBa, and VTi were detected and identified by EPR. Current-voltage characteristics (I-V) of PTCR BaTiO 3 were analyzed in light of space-charge-limited-current, trap-filled-limited-current, Frenkel-Poole, small polaron, and double-Schottky barrier models. It was shown that for the double-Schottky barrier model, a partial stabilisation of the potential barrier is expected when the Fermi level is pinned at grain boundaries by a high density of the interface states. The deviation of I-V characteristics of BaTiO3 in the region of the PTCR effect can be explained by dependence of the population of the interface electron states on applied voltage. Based on the Seebeck and Hall effect measurements, it was found that in the range of 100--300 K, the drift mobility of electrons in BaTiO 3 is not thermally activated, which supports the concept of conduction band electron transport rather than small radii polaron hopping. However, further study over a wider temperature range and on better quality crystals is required to unequivocally clarify the electron transport mechanism in BaTiO 3. Phase composition, degree of cation ordering, and dielectric properties of complex perovskites with general formula Ba(B' 1/3B″2/3)O3 where B' = Mg, Zn, Ni, and B″ = Nb, Ta were analyzed

  16. Optical and electronic properties of semiconducting nanoparticles; Optische und elektronische Eigenschaften von halbleitenden Nanopartikeln

    Energy Technology Data Exchange (ETDEWEB)

    Gondorf, Andreas

    2011-10-07

    In the present thesis, the electronic properties of semiconducting nanoparticles are investigated. The I-V-characteristics of a submonolayer of silicon nanoparticles, embedded in a Si{sub 3}N{sub 4}-matrix are calculated. The calculated results are compared to those found experimentally by Cho et al. It is investigated whether quantization effects, like the Coulomb blockade, can also be observed in systems, which contain many particles. Compacted silicon and germanium nanoparticle powders are analyzed by reflection measurements. The goal is to determine the carrier density and to find how the core-shell-structure (Ge/Si core and Ge/Si oxide shell) affects the reflection spectra. Furthermore, the influence of doping on the properties of the nanoparticles is investigated. Optical spectroscopy and magneto-transport measurements are performed on thin films, consisting of indium tin oxide nanoparticles (ITO nanoparticles). In optical spectroscopy the dielectric function in the high frequency region is determined. With the known dielectric function the charge carrier concentration as well as the mobility can be calculated. With magnetotransport measurements it is possible to measure the Hall voltage and the macroscopic conductivity. By taking into account the theoretically derived correction factor [Kharitonov, 2008] the carrier density and macroscopic mobility can be determined. Thus, the combination of the two measurement methods allows an insight into the electronic structure of this system. Additionally, layers consisting of ITO nanoparticles exhibit a decreasing resistivity when a magnetic field is applied perpendicular to the current orientation. This effect is called negative transverse magnetoresistance. The experimental results can be explained by the weak localization theory of granular systems. For the dephasing time {tau}{sub H}, however, we find a different dependence on the magnetic field than predicted by theory (experiment: 1/{tau}{sub H} {proportional

  17. 技术势差、进口贸易溢出与生产率空间差异——基于双门槛效应的检验%Technology Gap, Technology Spillovers of Import and Difference on TFP Growth: Based on Double-edged Threshold Effect Analysis

    Institute of Scientific and Technical Information of China (English)

    沈能; 李富有

    2012-01-01

    本文利用我国1992-2010年的省际面板数据,构建门槛模型实证分析进口贸易技术溢出及其技术势差的门槛效应。研究结果表明:进口贸易技术溢出在我国存在显著的技术势差的双门槛效应。在技术水平较高的沿海地区,由于技术势差较小使得进口贸易的溢出效果并不十分明显,但相对的自主创新弹性很高;在中等技术水平地区,由于技术势差的增强,这些地区正处在由模仿向创新转变的关键时期;而在技术落后地区,则需要加强人力资本积累,增强国际技术溢出的吸收能力,才能实现技术的跨越发展。%A threshold model is constructed based on Chinese panel data to analyze the technology spillovers of import and its "threshold effect" on tech nology gap. The results show that the technology spillovers of import have the "dualthreshold effect" on the technology gap. Due to a smaller technology gap, higher level of skills makes the import trade spillover effect more clear in coastal area, but the elasticity of independent inno vation is relatively higher. In the middle level of technology areas, due to the in creasing technology gap, these areas are in the transition from imitation to innova tion. In the backward technology areas, enhancing human capital accumulation to absorb the international technology spillovers is an important approach to enhance technology development.

  18. The influence of semiconductive binary Sb2S3-Yb3S4 system on electrical conductivity property of epoxy composites

    Science.gov (United States)

    Soydal, Ulku; Ahmetli, Gulnare; Kocaman, Suheyla

    2014-05-01

    The purpose of this study is to develop the semiconductive composites. Semiconducting glass (SG) binary system Sb2S3-Yb3S4 in mole ratio 1:1 was synthesized and was doped with I2. Next, electrically conductive DGEBA-type epoxy resin (ER)/SG-filled composites and epoxy toluene oligomer (ETO) modified epoxy resin-SG filled composites were developed with 3-10 wt. % of fillers and characterized. As a result, the effects of the modifier and amount of semiconductive filler on the electrical properties of commercial epoxy resin were examined. Percolation concentration was 7 wt. % for all composites. For the SG-reinforced composites, the dispersion of the fillers is investigated by X-ray diffraction (XRD) and by scanning electron microscopy (SEM).

  19. In-situ crosslinking and n-doping of semiconducting polymers and their application as efficient electron-transporting materials in inverted polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Namchul; Yip, Hin-Lap; Davies, Joshua A.; Kazarinoff, Peter D.; Segawa, Yukari; Luscombe, Christine K. [Department of Materials Science and Engineering, University of Washington, Seattle, WA (United States); Zeigler, David F.; Durban, Matthew M.; O' Malley, Kevin M. [Department of Chemistry, University of Washington, Seattle, WA (United States); Jen, Alex K.Y. [Department of Materials Science and Engineering, University of Washington, Seattle, WA (United States); Department of Chemistry, University of Washington, Seattle, WA (United States)

    2011-11-15

    In this study, we demonstrate in-situ n-doping and crosslinking of semiconducting polymers as efficient electron-transporting materials for inverted configuration polymer solar cells. The semiconducting polymers were crosslinked with bis(perfluorophenyl) azide (bis-PFPA) to form a robust solvent-resistant film, thereby preventing solvent-induced erosion during subsequent solution-based device processing. In addition, chemical n-doping of semiconducting polymers with (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine (N-DMBI) substantially improved the power conversion efficiency of solar cells from 0.69% to 3.42%. These results open the way for progress on generally applicable polymeric interface materials, providing not only high device performance but also an effective fabrication method for solution-processed multilayer solar cell devices. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. RFID technologies for imported foods inspection

    Science.gov (United States)

    Food-borne illness typically occurs due to contamination of food products with Escherichia coli, Salmonella spp., Listeria monocytogenes and other pathogens. Unfortunately, it takes several weeks to identify the source of such contamination, possibly due to lack of a central database system that is ...

  1. [Importance of interfacial characteristics in pharmaceutical technology].

    Science.gov (United States)

    Dredán, Judit; Csóka, Gabriella; Marton, Sylvia; Antal, István

    2003-01-01

    Since drug release from the dosage forms has priority to absorption from the gastrointestinal system, physico-chemical characterisation of pharmaceutical systems is essential during the development of an optimal formulation with high efficacy and quality. Interfacial parameters of several pharmaceutical excipients were studied regarding their possible modifying effect on drug release from the dosage form. These inactive ingredients may influence the interfacial phenomena of the drug carrier system, which behaviour determines both the efficacy and the quality of the pharmaceutical preparation In this work authors deal mainly with the two introducing steps of the LADME model influenced by interfacial parameters on them, namely with the liberation of drug from the dosage form and with the characteristics influencing the absorption through biological membranes, respectively. The objective of the present work was to study modifying effects of excipients on drug liberation in connection with their physical and chemical characteristics such as interfacial tension of solid and liquid phases, wetting contact angle of solid phase and--a calculated quantity,--adhesion tension of the solid particles.

  2. Cyclopentadithiophene–naphthalenediimide polymers; synthesis, characterisation, and n-type semiconducting properties in field-effect transistors and photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Han [Department of Chemical Engineering, Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing-Hua University, 101, Sec. 2, Kuang-Fu Road, Hsin-Chu 30013, Taiwan (China); Kettle, Jeff [School of Electronics, Bangor University, Dean st., Bangor, Gwynedd, LL57 1UT Wales (United Kingdom); Horie, Masaki, E-mail: mhorie@mx.nthu.edu.tw [Department of Chemical Engineering, Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing-Hua University, 101, Sec. 2, Kuang-Fu Road, Hsin-Chu 30013, Taiwan (China)

    2014-04-01

    The synthesis, characterisation, and device performance of a series of cyclopentadithiophene (CPDT)-naphthalenediimide (NDI) donor-acceptor-donor (D-A-D) polymers is reported. The monomers with various alkyl chains are synthesised via direct arylation using palladium complex catalyst. The monomers are then polymerised by oxidative polymerisation using FeCl{sub 3} to provide high molecular weight polymers (M{sub n} = 21,800–76,000). The polymer films show deep-red absorption including near-infrared region up to 1100 nm to give optical bandgap of approximately 1.16 eV. The polymers exhibit only n-type semiconducting properties giving the highest electron mobility of 9 × 10{sup -3} cm{sup 2} V{sup −1} s{sup −1} in organic field-effect transistors (OFETs). Organic photovoltaic (OPV) devices are fabricated from solutions of the polymers as acceptors and poly(3-hexylthiophene) (P3HT) as a donor. - Highlights: • Cyclopentadithiophene–naphthalenediimide oligomers were prepared by direct arylation. • The oligomers were polymerised by oxidative reaction using iron(III)chloride. • The polymer films show deep-red absorption up to 1100 nm with a bandgap of 1.1 eV. • The polymers exhibit only n-type semiconducting properties in OFETs and OPVs.

  3. Effect of the semi-conductive properties of the passive layer on the current provided by stainless steel microbial cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Pons, Liz; Delia, Marie-Line; Basseguy, Regine [Laboratoire de Genie Chimique, CNRS - Universite de Toulouse, 4 allee Emile Monso BP 84234, 31030 Toulouse (France); Bergel, Alain, E-mail: alain.bergel@ensiacet.f [Laboratoire de Genie Chimique, CNRS - Universite de Toulouse, 4 allee Emile Monso BP 84234, 31030 Toulouse (France)

    2011-02-15

    Geobacter sulfurreducens biofilms were formed under constant polarisation at -0.6 V vs. Ag/AgCl on stainless steel cathodes to catalyse the reduction of fumarate. The time-evolution of the current strongly depended on the quality of the inoculum. Inoculating with young cells significantly shortened the initial lag-phase and using the same inoculum improved the reproducibility of the current-time curves. The whole set of experiments showed that 254SMO stainless steel provided higher current densities (on average 14.1 A/m{sup 2}) than biofilms formed on 316L stainless steel (on average 4.5 A/m{sup 2}). Biofilm coverage assessed by epifluorescent microscopy showed that coverage ratios were generally higher for 316L than for 254SMO. It must be concluded that 254SMO is more efficient in transferring electrons to bacterial cells than 316L. Mott-Schottky diagrams recorded on both materials under conditions of electrolysis in the absence of microorganisms showed that the surface oxide layers had similar n-type semi-conductive behaviour for potential values higher than the flat band potential. In contrast, 316L exhibited slight p-type behaviour at potential lower than the flat band potential, while 254SMO did not. The higher electrochemical performances of biocathodes formed on 254SMO are explained by semi-conductive properties of its passive layer, which prevented the p-type behaviour occurring in cathodic electrolysis conditions.

  4. Intraparticle Molecular Orbital Engineering of Semiconducting Polymer Nanoparticles as Amplified Theranostics for in Vivo Photoacoustic Imaging and Photothermal Therapy.

    Science.gov (United States)

    Lyu, Yan; Fang, Yuan; Miao, Qingqing; Zhen, Xu; Ding, Dan; Pu, Kanyi

    2016-04-26

    Optical theranostic nanoagents that seamlessly and synergistically integrate light-generated signals with photothermal or photodynamic therapy can provide opportunities for cost-effective precision medicine, while the potential for clinical translation requires them to have good biocompatibility and high imaging/therapy performance. We herein report an intraparticle molecular orbital engineering approach to simultaneously enhance photoacoustic brightness and photothermal therapy efficacy of semiconducting polymer nanoparticles (SPNs) for in vivo imaging and treatment of cancer. The theranostic SPNs have a binary optical component nanostructure, wherein a near-infrared absorbing semiconducting polymer and an ultrasmall carbon dot (fullerene) interact with each other to induce photoinduced electron transfer upon light irradiation. Such an intraparticle optoelectronic interaction augments heat generation and consequently enhances the photoacoustic signal and maximum photothermal temperature of SPNs by 2.6- and 1.3-fold, respectively. With the use of the amplified SPN as the theranostic nanoagent, it permits enhanced photoacoustic imaging and photothermal ablation of tumor in living mice. Our study thus not only introduces a category of purely organic optical theranostics but also highlights a molecular guideline to amplify the effectiveness of light-intensive imaging and therapeutic nanosystems.

  5. Efficient Charge Extraction and Slow Recombination in Organic-Inorganic Perovskites Capped with Semiconducting Single-Walled Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ihly, Rachelle; Dowgiallo, Anne-Marie; Yang, Mengjin; Schulz, Philip; Stanton, Noah J.; Reid, Obadiah G.; Ferguson, Andrew J.; Zhu, Kai; Berry, Joseph J.; Blackburn, Jeffrey L.

    2016-04-01

    Metal-halide based perovskite solar cells have rapidly emerged as a promising alternative to traditional inorganic and thin-film photovoltaics. Although charge transport layers are used on either side of perovskite absorber layers to extract photogenerated electrons and holes, the time scales for charge extraction and recombination are poorly understood. Ideal charge transport layers should facilitate large discrepancies between charge extraction and recombination rates. Here, we demonstrate that highly enriched semiconducting single-walled carbon nanotube (SWCNT) films enable rapid (sub-picosecond) hole extraction from a prototypical perovskite absorber layer and extremely slow back-transfer and recombination (hundreds of microseconds). The energetically narrow and distinct spectroscopic signatures for charges within these SWCNT thin films enables the unambiguous temporal tracking of each charge carrier with time-resolved spectroscopies covering many decades of time. The efficient hole extraction by the SWCNT layer also improves electron extraction by the compact titanium dioxide electron transport layer, which should reduce charge accumulation at each critical interface. Finally, we demonstrate that the use of thin interface layers of semiconducting single-walled carbon nanotubes between the perovskite absorber layer and a prototypical hole transport layer improves device efficiency and stability, and reduces hysteresis.

  6. Research on Effect of Export upon Imported Technology in High-tech Industry%出口对高技术产业引进技术的影响机制研究

    Institute of Scientific and Technical Information of China (English)

    俞立平; 李守伟; 刘骏

    2016-01-01

    With high-tech industry export growing and proportion of imported technology declining, this paper firstly analyzes the mechanism of action which export affects the introduction of technology and considers the positive mechanisms,which contain export demand and manufacturing transfer in developed countries. Nevertheless,the negative mechanisms mainly reflect in the low-end of export commodity structure, which leads to the shortage of technical requirements,export of some high-end products results in reducing demand and international competition leads to that enterprises pay attention to research on development and reduce demand. Based on the panel data model and Bayesian vector autoregressive model, the results show the elasticity coefficient of export to imported technology is negative, therefore the negative mechanism is more than the positive, the fundamental cause is that the structure of China’s exported commodity is low-end and the relationship between export and imported technology is an u-shaped curve.%针对我国高技术产业出口不断增长与引进技术比重不断下降的现状,本文首先分析了出口对引进技术的作用机制,认为其正向机制包括出口创汇需求、发达国家制造业转移,负向机制主要体现在出口商品结构低端化导致引进技术需求不足、部分高端产品出口对引进技术需求降低、国际竞争导致企业重视研发降低引进技术需求。基于面板数据模型和贝叶斯向量自回归模型的研究结果表明,出口对引进技术影响的弹性系数为负,说明负向机制大于正向机制,其根本原因是我国出口商品结构低端化所致,出口与引进技术的关系呈现 U 型曲线。

  7. THE RELATIONSHIP BETWEEN R&D ACTIVITIES,TECHNOLOGY IMPORT SPILL-OVER AND FIRM PERFORMANCE%自主研发与技术引进对企业绩效影响差异分析

    Institute of Scientific and Technical Information of China (English)

    周新苗; 唐绍祥

    2011-01-01

    This study analyzed the impact of R&D and technology import on the firm performance in Shanghai. We considered R&D and technology spill-over as heterogeneous treatments and considered an econometric matching, taking a possible selection bias into account. The results show that, compared with companies without any treatment, firms that received either or both of the treatments yield positive effects. Technology import spill-over influences the firm's profit and firm's labor productivity more significantly while R&D was more important in improving firm's TFP. It indicated that the positive effects induced by spillovers in technology trade and R&D activities should be fully utilized by most domestic companies in Shanghai.%以上海工业企业为研究样本分析了企业自主研发和技术引进对企业绩效的不同贡献.文中将两种不同的促进技术进步策略作异质性的分析处理,同时考虑模型的选择偏差,再通过计量方法的匹配,做基于倾向得分的平均处理效应估计.研究结果显示,同不做任何技术创新与引进的企业相比,试图通过技术进步寻求发展的企业均对企业绩效产生了积极效应.其中技术引进方式对企业的当期利润和企业劳动生产率的提高更优于自主研发方式,而自主研发对于企业TFP的贡献却是大于技术引进的.研究还显示这两种技术进步方式对于不同所有制结构的企业作用不同.

  8. On the Importance of Art Literacy of Science and Technology Talents in our Country%论我国科技人才艺术素养的重要性

    Institute of Scientific and Technical Information of China (English)

    李剑平; 杨咏东; 李静媛

    2013-01-01

    科学与艺术是相辅相成、不可分割的.我国科技人才大都缺乏艺术素养,创造才能发挥受到限制,阻碍了科学技术研究发展.良好的艺术素养对科技人才的创造力和思维技能、良好人格的形成、工作激情、减轻工作压力、交际与沟通能力等方面具有重要的影响作用,科技人才应该努力提高艺术素养,为科学技术发展做出更大的贡献.%Science and arts and humanities are complementary and inseparable. In our country, most of scientific and technical workers lack the literacy of humanities and arts, which limits the creative ability to be brought into full play and also hinders the development of scientific and technological research. Good humane and artistic literacy has an important influence on not only the creativity and thinking skills of scientific and technical workers, but also the formation of a good personality and the passion for work. In addition, it plays an important role in reducing stress and improving communication skills. Scientific and technological workers should strive to improve the literacy of humane and artistic literacy, so that they can make a greater contribution to the development of science and technology.

  9. Technological Structure of China' Machinery Imports and Its Capital-embodied Technological Spillover Effect%我国进口机械设备的技术结构及其资本体现式技术溢出效应

    Institute of Scientific and Technical Information of China (English)

    王林辉; 苏碧娟; 董直庆

    2011-01-01

    This paper employs the import data of over 60 types of machinery in 107 countries from 1985 to 2007,and the relative weight of exports production shares to measure the technological content of China's machinery imports and the technological structure.Then it studies the capital-embodied technological spillover effect of machinery imports by constructing a model concerning the relationshipbetween technological level of machinery imports and total factor productivity from the product angle.The results are as follows: firstly,the technological structure of China's machinery imports is constantly being upgraded,and the proportion of medium-tech and high-tech machinery imports is increasing year by year while the proportion of low-tech machinery imports is declining continuously;secondly,developing countries including China mainly import medium-tech machinery for lack of funds,technology and human capital,while developed countries mainly import high-tech machinery because of the advantages of funds and human capital;thirdly,the capital-embodied technological spillover effect of China's machinery imports is significant,which mainly plays a role in non-neutral technological progress.%文章利用1985-2007年世界107个国家SITC三位码分类下60多类机械设备进口数据,以出口品生产世界份额的相对权重,测度我国进口机械设备的技术含量和技术结构,并从产品层面构建进口机械设备技术水平与全要素生产率关系模型,检验进口机械设备的资本体现式技术溢出效应。结果显示:(1)我国进口机械设备的技术结构不断升级,中高技术含量和中等技术含量的机械设备进口比重逐年提高,低技术含量机械设备进口比重持续下降。(2)发达国家源于资金和人力资本优势主要引进高技术含量的机械设备,而包括我国在内的发展中国家受资金、技术水平和人力资源的约束,则以进口中等技术含

  10. Optical properties of beta-iron silicide, ruthenium silicide and osmium silicide: Semiconducting transition metal silicides

    Science.gov (United States)

    Birdwell, Anthony Glen

    2001-09-01

    Various optical techniques were used to study the semiconducting transition metal silicides of β- FeSi2, Ru2Si3, and OsSi2. The Raman spectra of ion beam synthesized (IBS) β-FeSi 2 were shown to provide evidence of a net tensile stress in these IBS materials. Possible origins of the observed stress were suggested and a simple model was proposed in order to calculate a value of the observed stress. A correlation between the tensile stress, the nature of the band gap, and the resulting light emitting properties of IBS β-FeSi2 was suggested. The photoreflectance (PR) spectra of IBS β- FeSi2 reveals a direct gap at 0.815 eV and were shown to agree with the band gap value obtained by photoluminescence (PL) once the adjustments for the temperature difference and trap related recombination effects were made. This provides very convincing evidence for intrinsic light emission from IBS β- FeSi2. Furthermore, a model was developed that helps to clarify the variety of inconsistent results obtained by optical absorption measurements. When the results of PL and PR were inserted into this model, a good agreement was obtained with our measured optical absorption results. We also obtained PR spectra of β-FeSi 2 thin films grown by molecular beam epitaxy. These spectra reveal the multiple direct transitions near the fundamental absorption edge of β-FeSi 2 that were predicted by theory. We suggest an order of these critical point transitions following the trends reported in the theoretical investigations. Doping these β-FeSi2 thin films with small amounts of chromium was shown to have a measurable effect on the interband optical spectra. We also report on the effects of alloying β- FeSi2 with cobalt. A decrease in the critical point transitions nearest the fundamental absorption edge was observed as the cobalt concentration increased. Finally, Raman spectroscopy was used to study the vibrational properties of β-FeSi2. The measured Raman spectra agreed very well with the

  11. Nanostructured p-type semiconducting transparent oxides: promising materials for nano-active devices and the emerging field of "transparent nanoelectronics".

    Science.gov (United States)

    Banerjee, Arghya; Chattopadhyay, Kalyan K

    2008-01-01

    Transparent conducting oxides (TCO) with p-type semiconductivity have recently gained renewed interest for the fabrication of all-oxide transparent junctions, having potential applications in the emerging field of 'Transparent' or 'Invisible Electronics'. This kind of transparent junctions can be used as a "functional" window, which will transmit visible portion of solar radiation, but generates electricity by the absorption of the UV part. Therefore, these devices can be used as UV shield as well as UV cells. In this report, a brief review on the research activities on various p-TCO materials is furnished along-with the fabrication of different transparent p-n homojunction, heterojunction and field-effect transistors. Also the reason behind the difficulties in obtaining p-TCO materials and possible solutions are discussed in details. Considerable attention is given in describing the various patent generations on the field of p-TCO materials as well as transparent p-n junction diodes and light emitting devices. Also, most importantly, a detailed review and patenting activities on the nanocrystalline p-TCO materials and transparent nano-active device fabrication are furnished with considerable attention. And finally, a systematic description on the fabrication and characterization of nanocrystalline, p-type transparent conducting CuAlO(2) thin film, deposited by cost-effective low-temperature DC sputtering technique, by our group, is furnished in details. These p-TCO micro/nano-materials have wide range of applications in the field of optoelectronics, nanoelectronics, space sciences, field-emission displays, thermoelectric converters and sensing devices.

  12. The importance of the stimulation vessels in the Brazilian offshore basins: a history of technological evolution; A importancia dos barcos de estimulacao em bacias offshore brasileiras: uma historia de evolucao tecnologica

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Ricardo S.; Prata, Fernando Gaspar M.; Dean, Gregory D. [BJ Services do Brasil Ltda., RJ (Brazil)

    2004-07-01

    The Campos Basin is known as one of the most challenging deep water basins in the world. Currently there are thirty-seven platforms, more than a thousand oil wells, and about 4200 kilometers of submarine pipelines, having produced more than 1,2 billion barrels of oil per year and 15,7 million cubic meters of gas per day. The Campos Basin is responsible for more than 80% of Brazil's national production. Brazil intends to produce 2,2 million barrels of oil per day by 2007, when it will reach self-sufficiency. Therefore, the continued development of the offshore basins, such as Campos, Santos and Espirito Santo will be critical to meet this goal. In this context, the technological evolution of the vessels that render stimulation services is of fundamental importance to improve job quality, reduce time, protect with the environment, enable efficient communication, and ensure operational viability of new techniques. This paper reports on the history of this vessels, describing and illustrating new and state-of-the-art technology, historical cases of pioneering operations, data transmission in real time and the benefits for offshore operators with a global vision. (author)

  13. Efficient separation of semiconducting single-wall carbon nanotubes by surfactant-composition gradient in gel filtration

    Science.gov (United States)

    Thendie, Boanerges; Omachi, Haruka; Miyata, Yasumitsu; Shinohara, Hisanori

    2017-01-01

    Gel filtration is a powerful method of separating and purifying semiconducting single-wall carbon nanotubes (s-SWCNTs) from their metallic (m-) counterpart. However, a small amount of m-SWCNTs usually remains, thus reducing the purity of the s-SWCNTs obtained. We have investigated the effect of elution with a gradient concentration of the surfactant on the separation and purity of s-SWCNTs. By utilizing the controlled low-gradient elution (CLGE) that we have developed, the purity of s-SWCNTs is improved to 94% from the 90% obtained with the conventional separation. Furthermore, CLGE simultaneously allows diameter-based separation of small-diameter s-SWCNTs, which indicates a promising utilization of CLGE for s-SWCNT separation.

  14. Q-switched waveguide laser based on two-dimensional semiconducting materials: tungsten disulfide and black phosphorous.

    Science.gov (United States)

    Tan, Yang; Guo, Zhinan; Ma, Linan; Zhang, Han; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2016-02-01

    Owing to their unique properties, graphene-like two dimensional semiconducting materials, including Tungsten Disulfide (WS2) and Black Phosphorous (BP), have attracted increasing interest from basic research to practical applications. Herein, we demonstrated the ultrafast nonlinear saturable absorption response of WS2 and BP films in the waveguide structure. Through fabricating WS2 and BP films by evaporating the solutions on glass wafers. Saturable absorber films were attached onto the end-facet of the waveguide, which therefore constitutes a resonant cavity for the waveguide laser. Under a pump laser at 810 nm, we could obtain a stable Q-switched operation in the waveguide structure. This work indicated the significant potential of WS2 and BP for the ultrafast waveguide laser.

  15. On the possibility to use semiconductive hybrid pixel detectors for study of radiation belt of the Earth

    CERN Document Server

    Guskov, A; Smolyanskiy, P; Zhemchugov, A

    2015-01-01

    The scientific apparatus "Gamma-400" designed for study of hadron and electromagnetic components of cosmic rays will be launched to an elliptic orbit with the apogee of about 300 000 km and the perigee of about 500 km. Such a configuration of the orbit allows it to cross periodically the radiation belt and the outer part of magnetosphere. We discuss the possibility to use hybrid pixel detecters based on the Timepix chip and semiconductive sensors on board the "Gamma-400" apparatus. Due to high granularity of the sensor (pixel size is 55 $mu$m) and possibility to measure independently an energy deposition in each pixel, such compact and lightweight detector could be a unique instrument for study of spatial, energy and time structure of electron and proton components of the radiation belt.

  16. High-quality, highly concentrated semiconducting single-wall carbon nanotubes for use in field effect transistors and biosensors.

    Science.gov (United States)

    Li, Wen-Shan; Hou, Peng-Xiang; Liu, Chang; Sun, Dong-Ming; Yuan, Jiangtan; Zhao, Shi-Yong; Yin, Li-Chang; Cong, Hongtao; Cheng, Hui-Ming

    2013-08-27

    We developed a simple and scalable selective synthesis method of high-quality, highly concentrated semiconducting single-wall carbon nanotubes (s-SWCNTs) by in situ hydrogen etching. Samples containing ~93% s-SWCNTs were obtained in bulk. These s-SWCNTs with good structural integrity showed a high oxidation resistance temperature of ~800 °C. Thin-film transistors based on the s-SWCNTs demonstrated a high carrier mobility of 21.1 cm(2) V(-1) s(-1) at an on/off ratio of 1.1 × 10(4) and a high on/off ratio of 4.0 × 10(5) with a carrier mobility of 7.0 cm(2) V(-1) s(-1). A biosensor fabricated using the s-SWCNTs had a very low dopamine detection limit of 10(-18) mol/L at room temperature.

  17. Direct observation of spin-layer locking by local Rashba effect in monolayer semiconducting PtSe2 film

    Science.gov (United States)

    Yao, Wei; Wang, Eryin; Huang, Huaqing; Deng, Ke; Yan, Mingzhe; Zhang, Kenan; Miyamoto, Koji; Okuda, Taichi; Li, Linfei; Wang, Yeliang; Gao, Hongjun; Liu, Chaoxing; Duan, Wenhui; Zhou, Shuyun

    2017-01-01

    The generally accepted view that spin polarization in non-magnetic solids is induced by the asymmetry of the global crystal space group has limited the search for spintronics materials mainly to non-centrosymmetric materials. In recent times it has been suggested that spin polarization originates fundamentally from local atomic site asymmetries and therefore centrosymmetric materials may exhibit previously overlooked spin polarizations. Here, by using spin- and angle-resolved photoemission spectroscopy, we report the observation of helical spin texture in monolayer, centrosymmetric and semiconducting PtSe2 film without the characteristic spin splitting in conventional Rashba effect (R-1). First-principles calculations and effective analytical model analysis suggest local dipole induced Rashba effect (R-2) with spin-layer locking: opposite spins are degenerate in energy, while spatially separated in the top and bottom Se layers. These results not only enrich our understanding of the spin polarization physics but also may find applications in electrically tunable spintronics.

  18. Design of L21-type antiferromagnetic semiconducting full-Heusler compounds: A first principles DFT + GW study

    Science.gov (United States)

    Tas, M.; Şaşıoǧlu, E.; Friedrich, C.; Blügel, S.; Galanakis, I.

    2017-02-01

    Antiferromagnetic spintronics is an on-going growing field of research. Employing both standard density functional theory and the GW approximation within the framework of the full-potential linearized augmented-plane-wave method, we study the electronic and magnetic properties of seven potential antiferromagnetic semiconducting Heusler compounds with 18 (or 28 when Zn is present) valence electrons per unit cell. We show that in these compounds G-type antiferromagnetism is the ground state and that they are all either semiconductors (Cr2ScP, Cr2TiZn, V2ScP, V2TiSi, and V3Al) or semimetals (Mn2MgZn and Mn2NaAl). The many-body corrections have a minimal effect on the electronic band structure with respect to the standard electronic structure calculations.

  19. Monitoring and Pre-warning Technology of Important Devices of Nuclear Power Plant%核电厂重要设备的监视与预警技术

    Institute of Scientific and Technical Information of China (English)

    顾海霞; 王婷; 刘高俊; 谭珂

    2014-01-01

    针对核电厂运行过程中出现的重要设备的异常变化,利用数据挖掘技术,建立重要设备的动态规则库,在核电厂实时信息监控系统的实时数据和历史数据基础上,分析核电厂重要设备的变化趋势和规律,对重要设备的异常情况进行实时在线监视和预警。为操纵员提供判断依据,降低核事故发生的几率,从而有效地提高了核电厂运行的安全性。%Aiming to find out abnormal changes of important devices in nuclear power plant operation process ,combined with data mining technology ,dynamic regular library of important devices was set up .Based on the real‐time data and the history data of real‐time information monitoring system in nuclear power plant , trend and regularity of important devices of nuclear power plant were obtained and analyzed ,so the important devices can be monitored and pre‐warn online .The basis can be provided for the opera‐tors ,so the probability of nuclear accidents would be reduced and the safety of operation for nuclear power plant can be effectively improved .

  20. Importance of hemodialysis-related outcomes: comparison of ratings by a self-help group, clinicians, and health technology assessment authors with those by a large reference group of patients

    Science.gov (United States)

    Janssen, Inger M; Scheibler, Fueloep; Gerhardus, Ansgar

    2016-01-01

    Background The selection of important outcomes is a crucial decision for clinical research and health technology assessment (HTA), and there is ongoing debate about which stakeholders should be involved. Hemodialysis is a complex treatment for chronic kidney disease (CKD) and affects many outcomes. Apart from obvious outcomes, such as mortality, morbidity and health-related quality of life (HRQoL), others such as, concerning daily living or health care provision, may also be important. The aim of our study was to analyze to what extent the preferences for patient-relevant outcomes differed between various stakeholders. We compared preferences of stakeholders normally or occasionally involved in outcome prioritization (patients from a self-help group, clinicians and HTA authors) with those of a large reference group of patients. Participants and methods The reference group consisted of 4,518 CKD patients investigated previously. We additionally recruited CKD patients via a regional self-help group, nephrologists via an online search and HTA authors via an expert database or personal contacts. All groups assessed the relative importance of the 23 outcomes by means of a discrete visual analog scale. We used descriptive statistics to rank outcomes and compare the results between groups. Results We received completed questionnaires from 49 self-help group patients, 19 nephrologists and 18 HTA authors. Only the following 3 outcomes were ranked within the top 7 outcomes by all 4 groups: safety, HRQoL and emotional state. The ratings by the self-help group were generally more concordant with the reference group ratings than those by nephrologists, while HTA authors showed the least concordance. Conclusion Preferences of CKD patients from a self-help group, nephrologists and HTA authors differ to a varying extent from those of a large reference group of patients with CKD. The preferences of all stakeholders should form the basis of a transparent approach so as to generate a

  1. Electrochemical and semiconducting properties of thin passive film formed on titanium in chloride medium at various pH conditions

    Energy Technology Data Exchange (ETDEWEB)

    Munirathinam, Balakrishnan, E-mail: blkrish88@gmail.com [Department of Metallurgical and Materials Enginneering, Indian Institute of Technology Madras, Chennai (India); Narayanan, R. [School of Mechanical and Building Sciences, Vellore Institute of Technology, Chennai (India); Neelakantan, Lakshman, E-mail: nlakshman@iitm.ac.in [Department of Metallurgical and Materials Enginneering, Indian Institute of Technology Madras, Chennai (India)

    2016-01-01

    The electrochemical behavior of titanium has been investigated in chloride electrolyte of different pH values (2.1, 5.2 and 7.4). Potentiodynamic polarization studies showed wide passive behavior irrespective of change in pH. Passive films were grown by applying different passive potentials (0.2 to 0.6 V (vs SCE)) by recording chronoamperometric curves for duration of 8 h. Electrochemical impedance spectroscopy (EIS) measurements showed higher impedance values for the oxide layer grown in neutral pH condition and for oxides formed at higher formation potentials. Emphasis is made mainly on the properties of titanium oxide estimated by Mott-Schottky analysis, which shows that passive film formed, is of n-type semiconducting film and the donor concentration is in the order of 10{sup 20} cm{sup −3}. The calculated diffusivity of point defects is in the range of (0.5 to 2.5) × 10{sup -16} cm{sup 2}s{sup −1} and tends to decrease with increase in electrolyte pH. Surface morphology of the passive films was examined using scanning electron microscope and surface roughness was characterized using confocal microscope. Ex- situ ellipsometry measurements were performed to analyze the optical constants of the oxide layer and to determine the oxide thickness. The thickness is in the range of 3.5 to 5.8 nm and comparable to the calculated values. - Highlights: • Thin passive film was grown potentiostatically on titanium at various pH conditions • Passive films formed on titanium are of n-type semiconducting nature. • Diffusivity of point defects decreases with increase in pH.

  2. 中间产品进口对中国高技术产品出口技术含量的影响%Import of Intermediate Products Impact on Exports Technology of China's High-tech Products

    Institute of Scientific and Technical Information of China (English)

    肖浩; 胡小娟; 辛丽萍

    2015-01-01

    在新贸易理论的指导下,国际贸易模式不断发展与创新,产品内贸易盛行。本文根据2000—2013年高技术产品五大行业面板数据,基于豪斯曼构建的产品出口复杂度指标对中国高技术产品的出口技术含量进行测度,得出这期间其出口技术含量呈现逐年上升的趋势。本文引入虚拟变量,实证分析 FDI、R&D 及中间产品进口五大行业对其出口技术含量的影响。结果表明,总体来说 FDI、R&D 和中间产品进口均有助于提升产品的出口技术含量;但对细分行业来说,中间产品进口与出口技术含量的关系是不确定的,需要区分不同类型的产品,电子及通信设备、电子计算机及办公设备和医疗设备及仪器仪表三类产品的中间产品进口会促进高技术产品出口技术含量的提升,而医药和航空航天器产品的中间产品进口则会阻碍其出口技术含量的提升。%Under the guidance of the new trade theory,the modes of international trade are developing and in-novating,and trades in products are popular.In this paper,according to the five industry panel data from 2000 to 2013,and export complexity index based on Hausmann,it is concluded that the export technical content showed a trend of rising year by year.This paper introduces virtual variables,analyzing FDI,R&D and import of intermediate products,and the results show that the overall FDI,R&D and the import of intermediate products can promote the export of the product technology content,but for niche business,the import and export of intermediate product tech-nology content are not quite related,which need to distinguish among different types of products.Importing in terme-diate products of electronic and communication equipment,computers and office equipment,and medical equipment and instrumentation can promote the export of high-tech products,while importing intermediate products of pharma-ceutical and aerial will

  3. Why is Astronomy Important?

    CERN Document Server

    Rosenberg, Marissa; Bladon, Georgia; Christensen, Lars Lindberg

    2013-01-01

    For a long time astronomers and other scientists believed that the importance of their work was evident to society. But in these difficult days of financial austerity, even the most obvious benefits of science have to undergo careful scrutiny. Eradicating poverty and hunger is a worldwide priority, and activities that do not directly attempt to resolve these issues can be hard to justify and support. However, several studies have told us that investing in science education, research and technology provides a great return (not only economically, but culturally and indirectly for the population in general and has helped countries to face and overcome crises. The scientific and technological development of a country or region is closely linked to its human development index) a statistic that is a measure of life expectancy, education and income.

  4. Thermally activated technologies: Technology Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2003-05-01

    The purpose of this Technology Roadmap is to outline a set of actions for government and industry to develop thermally activated technologies for converting America’s wasted heat resources into a reservoir of pollution-free energy for electric power, heating, cooling, refrigeration, and humidity control. Fuel flexibility is important. The actions also cover thermally activated technologies that use fossil fuels, biomass, and ultimately hydrogen, along with waste heat.

  5. Thermally activated technologies: Technology Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2003-05-01

    The purpose of this Technology Roadmap is to outline a set of actions for government and industry to develop thermally activated technologies for converting America’s wasted heat resources into a reservoir of pollution-free energy for electric power, heating, cooling, refrigeration, and humidity control. Fuel flexibility is important. The actions also cover thermally activated technologies that use fossil fuels, biomass, and ultimately hydrogen, along with waste heat.

  6. DNA Block Copolymer Doing It All : From Selection to Self-Assembly of Semiconducting Carbon Nanotubes

    NARCIS (Netherlands)

    Kwak, Minseok; Gao, Jia; Prusty, Deepak K.; Musser, Andrew J.; Markov, Vladimir A.; Tombros, Nikolaos; Stuart, Marc C.A.; Browne, Wesley R.; Boekema, Egbert J.; Brinke, Gerrit ten; Jonkman, Harry T.; Wees, Bart J. van; Loi, Maria A.; Herrmann, Andreas

    2011-01-01

    A potentially scalable self-assembly method for single-walled carbon nanotubes (SWNTs) involves the use of amphiphilic DNA block copolymers. One such hybrid is able to cover the entire area of solution-based SWNT technologies, from selective dispersion to nondestructive functionalization to high-yie

  7. Sucessful Eexperience of France Attaching Importance to Social Development and The People's Livelihood Science and Technology%关于法国重视社会发展和民生科技的成功经验

    Institute of Scientific and Technical Information of China (English)

    蒯强

    2009-01-01

    In the aspects of great development of nuclear energy, emphasis on power saving and emission mitigation, popularization of power saving buildings, strengthening territorial management, constructing competitive innovation parks, preventing natural disaster, improving social security system and health insurance system, enhancing medical research, emphasis on food sanitation safety, popularizing popular-science knowledge, helping small and medium-sized enterprises with huge investment, holding environmental protection negotiation conferences, building scientific and technological innovation system, the paper mainly studied and reviewed the trends of France attaching importance to social development and the people's livelihood science and technology, and proposed the French sucessful experience is worth our referring and learning.%本文从大力发展核能事业、重视节能减排工作、努力推广节能建筑、加强国土整治建设、加强国土整治建设、创建竞争力创新园区、积极预防自然灾害、健全社会保障体系、医疗健康保险制度、提高医学研究水平、强调食品卫生安全、重视推广科普知识、巨资帮助中小企业、召开环保协商会议、建立科技创新体系等14个方面,重点研究和评述了法国重视社会发展和民生科技的情况,认为法国在加快推进以改善社会发展和强化民生科技为重点的社会建设方面之成功经验值得我国借鉴和学习.

  8. Prevention and Control Technology of Important Meat Goat Diseases in Anhui Province%安徽省肉用山羊重大疫病的防控技术

    Institute of Scientific and Technical Information of China (English)

    李立虎

    2015-01-01

    Anhui Province is one of main mutton production areas in China, and the main breed is the goat. With the rapid development of the mutton sheep industry, the prevention and control of epidemic diseases is getting more diffi-cult. The epidemic characteristics, clini-cal symptoms, pathologic autopsy and synthetical prevention and control tech-nology of important meat goat diseases were discussed to provide security guar-antee for healthy development of the meat goat industry in Anhui Province.%安徽是我国主要羊肉产区之一,肉羊的养殖主要以山羊为主.随着肉羊产业的迅速发展,疫病的防控难度加大.探讨羊的3类重大疫病的流行特点、临床症状、剖检特征和综合防控技术,为安徽省肉用山羊产业的健康发展提供安全保障.

  9. Magneto-optical absorption in semiconducting spherical quantum dots: Influence of the dot-size, confining potential, and magnetic field

    Directory of Open Access Journals (Sweden)

    Manvir S. Kushwaha

    2014-12-01

    Full Text Available Semiconducting quantum dots – more fancifully dubbed artificial atoms – are quasi-zero dimensional, tiny, man-made systems with charge carriers completely confined in all three dimensions. The scientific quest behind the synthesis of quantum dots is to create and control future electronic and optical nanostructures engineered through tailoring size, shape, and composition. The complete confinement – or the lack of any degree of freedom for the electrons (and/or holes – in quantum dots limits the exploration of spatially localized elementary excitations such as plasmons to direct rather than reciprocal space. Here we embark on a thorough investigation of the magneto-optical absorption in semiconducting spherical quantum dots characterized by a confining harmonic potential and an applied magnetic field in the symmetric gauge. This is done within the framework of Bohm-Pines’ random-phase approximation that enables us to derive and discuss the full Dyson equation that takes proper account of the Coulomb interactions. As an application of our theoretical strategy, we compute various single-particle and many-particle phenomena such as the Fock-Darwin spectrum; Fermi energy; magneto-optical transitions; probability distribution; and the magneto-optical absorption in the quantum dots. It is observed that the role of an applied magnetic field on the absorption spectrum is comparable to that of a confining potential. Increasing (decreasing the strength of the magnetic field or the confining potential is found to be analogous to shrinking (expanding the size of the quantum dots: resulting into a blue (red shift in the absorption spectrum. The Fermi energy diminishes with both increasing magnetic-field and dot-size; and exhibits saw-tooth-like oscillations at large values of field or dot-size. Unlike laterally confined quantum dots, both (upper and lower magneto-optical transitions survive even in the extreme instances. However, the intra

  10. Preparation and characterization of graphene-based vanadium oxide composite semiconducting films with horizontally aligned nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hye-Mi; Um, Sukkee, E-mail: sukkeeum@hanyang.ac.kr

    2016-05-01

    Highly oriented crystalline hybrid thin films primarily consisting of Magnéli-phase VO{sub 2} and conductive graphene nanoplatelets are fabricated by a sol–gel process via dipping pyrolysis. A combination of chemical, microstructural, and electrical analyses reveals that graphene oxide (GO)-templated vanadium oxide (VO{sub x}) nanocomposite films exhibit a vertically stacked multi-lamellar nanostructure consisting of horizontally aligned vanadium oxide nanowire (VNW) arrays along the (hk0) set of planes on a GO template, with an average crystallite size of 41.4 Å and a crystallographic tensile strain of 0.83%. In addition, GO-derived VO{sub x} composite semiconducting films, which have an sp{sup 3}/sp{sup 2} bonding ratio of 0.862, display thermally induced electrical switching properties in the temperature range of − 20 °C to 140 °C, with a transition temperature of approximately 65 °C. We ascribe these results to the use of GO sheets, which serve as a morphological growth template as well as an electrochemically tunable platform for enhancing the charge-carrier mobility. Moreover, the experimental studies demonstrate that graphene-based Magnéli-phase VO{sub x} composite semiconducting films can be used in advanced thermo-sensitive smart sensing/switching applications because of their outstanding thermo-electrodynamic properties and high surface charge density induced by the planar-type VNWs. - Highlights: • VO{sub x}-graphene oxide composite (G/VO{sub x}) films were fabricated by sol–gel process. • The G/VO{sub x} films mainly consisted of Magnéli-phase VO{sub 2} and reduced graphene sheets. • The G/VO{sub x} films exhibited multi-lamellar textures with planar VO{sub x} nanowire arrays. • The G/VO{sub x} films showed the thermo-sensitive electrical switching properties. • Effects of GOs on the electrical characteristics of the G/VO{sub x} films were discussed.

  11. Magneto-optical absorption in semiconducting spherical quantum dots: Influence of the dot-size, confining potential, and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kushwaha, Manvir S. [Department of Physics and Astronomy, Rice University, P.O. Box 1892, Houston, TX 77251 (United States)

    2014-12-15

    Semiconducting quantum dots – more fancifully dubbed artificial atoms – are quasi-zero dimensional, tiny, man-made systems with charge carriers completely confined in all three dimensions. The scientific quest behind the synthesis of quantum dots is to create and control future electronic and optical nanostructures engineered through tailoring size, shape, and composition. The complete confinement – or the lack of any degree of freedom for the electrons (and/or holes) – in quantum dots limits the exploration of spatially localized elementary excitations such as plasmons to direct rather than reciprocal space. Here we embark on a thorough investigation of the magneto-optical absorption in semiconducting spherical quantum dots characterized by a confining harmonic potential and an applied magnetic field in the symmetric gauge. This is done within the framework of Bohm-Pines’ random-phase approximation that enables us to derive and discuss the full Dyson equation that takes proper account of the Coulomb interactions. As an application of our theoretical strategy, we compute various single-particle and many-particle phenomena such as the Fock-Darwin spectrum; Fermi energy; magneto-optical transitions; probability distribution; and the magneto-optical absorption in the quantum dots. It is observed that the role of an applied magnetic field on the absorption spectrum is comparable to that of a confining potential. Increasing (decreasing) the strength of the magnetic field or the confining potential is found to be analogous to shrinking (expanding) the size of the quantum dots: resulting into a blue (red) shift in the absorption spectrum. The Fermi energy diminishes with both increasing magnetic-field and dot-size; and exhibits saw-tooth-like oscillations at large values of field or dot-size. Unlike laterally confined quantum dots, both (upper and lower) magneto-optical transitions survive even in the extreme instances. However, the intra-Landau level

  12. A rational design for the separation of metallic and semiconducting single-walled carbon nanotubes using a magnetic field

    Science.gov (United States)

    Luo, Chengzhi; Wan, Da; Jia, Junji; Li, Delong; Pan, Chunxu; Liao, Lei

    2016-06-01

    The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm2 V-1 s-1 and an on/off ratio of 106. We also established a model to quantitatively calculate the percentage of m-SWNTs on the substrate and this model shows a good match with the experimental data. Furthermore, our rational design also provides a new avenue for the growth of SWNTs with specific chirality and manipulated arrangement due to the difference of magnetic susceptibilities between different diameters, chiralities, and types.The separation of metallic (m-) and semiconducting (s-) single-walled carbon nanotubes (SWNTs) without causing contamination and damage is a major challenge for SWNT-based devices. As a facile and nondestructive tool, the use of a magnetic field could be an ideal strategy to separate m-/s-SWNTs, based on the difference of magnetic susceptibilities. Here, we designed a novel magnetic field-assisted floating catalyst chemical vapor deposition system to separate m-/s-SWNTs. Briefly, m-SWNTs are attracted toward the magnetic pole, leaving s-SWNTs on the substrate. By using this strategy, s-SWNTs with a purity of 99% could be obtained, which is enough to construct high-performance transistors with a mobility of 230 cm2 V-1 s-1 and an on/off ratio of 106. We also established a model to quantitatively calculate the percentage of m

  13. Synthesis and semiconducting properties of tin(II) sulfide: Application to photocatalytic degradation of Rhodamine B under sun light

    Energy Technology Data Exchange (ETDEWEB)

    Kabouche, S. [Laboratory of Electrochemistry-Corrosion, Metallurgy and Inorganic Chemistry, Faculty of Chemistry, U.S.T.H.B., BP 32, Algiers, 16111 (Algeria); Bellal, B. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of the Chemistry, U.S.T.H.B., BP 32, Algiers, 16111 (Algeria); Louafi, Y. [Laboratory of Electrochemistry-Corrosion, Metallurgy and Inorganic Chemistry, Faculty of Chemistry, U.S.T.H.B., BP 32, Algiers, 16111 (Algeria); Trari, M., E-mail: solarchemistry@gmail.com [Laboratory of Storage and Valorization of Renewable Energies, Faculty of the Chemistry, U.S.T.H.B., BP 32, Algiers, 16111 (Algeria)

    2017-07-01

    We have investigated the semiconducting and photoelectrochemical properties of SnS grown by a template-free chemical route using thiourea as precursor. Tin(II) sulfide is characterized by X-ray diffraction, scanning electron microscopy, diffuse reflectance and Raman spectroscopy. The X-ray diffraction indicates an orthorhombic SnS phase (SG: Pbnm) with a crystallite size of 52 nm while the optical measurements give a direct band gap of 1.33 eV. The Mott–Schottky plot exhibits a linear behavior, characteristic of n-type conductivity with a flat band potential of 0.19 V{sub SCE} and a donor density of 4.12 × 10{sup 18} cm{sup -3}. The electrochemical impedance spectroscopy (EIS) measured in the range (10{sup -2}–5 × 10{sup 4} Hz) shows one semicircle attributed to the bulk resistance (R{sub b} = 20.37 kΩ cm{sup 2}). The conduction band, located at 4.84 eV below vacuum, is made up of Sn{sup 2+:}5p while the valence band (6.17 eV) derives mainly from S{sup 2-}: 3p character. The energy band diagram, constructed from the photoelectrochemical characterization, predicts the photodegradation of Rhodamine B on SnS by H{sub 2}O{sub 2} generated photoelectrochemically. 88.46% of the initial concentration (10 mg L{sup -1}) disappears after adsorption and 4 h of exposure to solar light. The photoactivity is nearly restored during the second cycle and follows a second order kinetic with a rate constant of 1.55 × 10{sup -3} mg{sup -1} L min{sup -1}. - Highlights: • The semiconducting properties of SnS synthesized by chemical route are studied. • The n type conductivity is evidenced by chrono-amperometry and photoelectrochemistry. • The conduction band, located at 4.84 eV below vacuum, is made up of Sn{sup 2+}: 5p. • SnS was successfully used for the Rhodamine B oxidation under sunlight.

  14. Role of surface states in the Casimir force between semiconducting films

    CERN Document Server

    Govoni, Marco; Benassi, Andrea

    2010-01-01

    We present results of first principle calculations of the Casimir force between Si films of nanometric size, which show that it depends significantly upon the configuration of the surface atoms, and give evidence of the importance of surface states.

  15. Final Report for DE-FG36-08GO18007 "All-Inorganic, Efficient Photovoltaic Solid State Devices Utilizing Semiconducting Colloidal Nanocrystal Quantum Dots"

    Energy Technology Data Exchange (ETDEWEB)

    Vladimir Bulovic and Moungi Bawendi

    2011-09-30

    We demonstrated robust colloidal quantum dot (QD) photovoltaics with high internal quantum efficiencies. In our structures, device durability is derived from use of all-inorganic atmospherically-stable semiconducting metal-oxide films together with QD photoreceptors. We have shown that both QD and metal-oxide semiconducting films and contacts are amenable to room temperature processing under minimal vacuum conditions, enabling large area processing of PV structures of high internal efficiency. We generated the state of the art devices with power conversion efficiency of more than 4%, and have shown that efficiencies as high as 9% are achievable in the near-term, and as high as 17% in the long-term.

  16. Synthesis, characterization, and exciton dynamics of II-VI semiconducting nanomaterials and ab-initio studies for applications in explosives sensing

    OpenAIRE

    Cooper, Jason Kyle

    2013-01-01

    II-VI semiconducting nanostructures have been intensively researched as promising materials in applications including sensing, light emitting diodes (LEDs), lasers, photoelectrochemical (PEC) materials for water splitting and photo-catalysis, and dye or quantum dot sensitized solar cells. On the nanoscale, structural morphology plays a significant role in determining optical, electronic, and physical properties, and thus consequently affects the ultimate device properties. In zero-d...

  17. Photoacoustic Imaging: Semiconducting Oligomer Nanoparticles as an Activatable Photoacoustic Probe with Amplified Brightness for In Vivo Imaging of pH (Adv. Mater. 19/2016).

    Science.gov (United States)

    Miao, Qingqing; Lyu, Yan; Ding, Dan; Pu, Kanyi

    2016-05-01

    Despite the great potential of photoacoustic imaging in the life sciences, the development of smart activatable photoacoustic probes remains elusive. On page 3662, K. Pu and co-workers report a facile nanoengineering approach based on semiconducting oligomer nano-particles to develop ratiometric photoacoustic probes with amplified brightness and enhanced sensing capability for accurate photoacoustic mapping of pH in the tumors of living mice.

  18. Recognition and one-pot extraction of right- and left-handed semiconducting single-walled carbon nanotube enantiomers using fluorene-binaphthol chiral copolymers.

    Science.gov (United States)

    Akazaki, Kojiro; Toshimitsu, Fumiyuki; Ozawa, Hiroaki; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2012-08-01

    Synthesized single-walled carbon nanotubes (SWNTs) are mixtures of right- and left-handed helicity and their separation is an essential topic in nanocarbon science. In this paper, we describe the separation of right- and left-handed semiconducting SWNTs from as-produced SWNTs. Our strategy for this goal is simple: we designed copolymers composed of polyfluorene and chiral bulky moieties because polyfluorenes with long alkyl-chains are known to dissolve only semiconducting SWNTs and chiral binaphthol is a so-called BINAP family that possesses a powerful enantiomer sorting capability. In this study, we synthesized 12 copolymers, (9,9-dioctylfluorene-2,7-diyl)x((R)- or (S)-2,2'-dimethoxy-1,1'-binaphthalen-6,6-diyl)y, where x and y are copolymer composition ratios. It was found that, by a simple one-pot sonication method, the copolymers are able to extract either right- or left-handed semiconducting SWNT enantiomers with (6,5)- and (7,5)-enriched chirality. The separated materials were confirmed by circular dichroism, vis-near IR and photoluminescence spectroscopies. Interestingly, the copolymer showed inversion of SWNT enantiomer recognition at higher contents of the chiral binaphthol moiety. Molecular mechanics simulations reveal a cooperative effect between the degree of chirality and copolymer conformation to be responsible for these distinct characteristics of the extractions. This is the first example describing the rational design and synthesis of novel compounds for the recognition and simple sorting of right- and left-handed semiconducting SWNTs with a specific chirality.

  19. Optical properties of single-walled carbon nanotubes highly separated in semiconducting and metallic tubes functionalized with poly(vinylidene fluoride)

    Science.gov (United States)

    Matea, A.; Baibarac, M.; Baltog, I.

    2017-02-01

    In this paper, the interaction of poly(vinylidene fluoride) (PVDF) with single-walled carbon nanotubes (SWNTs) highly separated in metallic (M) and semiconducting (S) tubes is studied by resonant Raman scattering and FTIR spectroscopy. In this order, the PVDF/SWNTs membranes were prepared by the evaporation of dimethylformamide (DMF) from PVDF solutions containing i) the as-prepared SWNTs samples, i.e., as mixtures of metallic (33%) and semiconducting (66%) tubes (M + S-SWNTs), ii) SWNTs highly separated in metallic tubes (98%, M-SWNTs), and iii) SWNTs highly separated in semiconducting tubes (99%, S-SWNTs). An increase in the PVDF β phase weight, highlighted by the increase in the absorbance of IR band at 843 cm-1, is reported to take place in the presence of M + S-SWNTs and S-SWNTs. An increase of the PVDF γ crystalline phase weight is reported for the PVDF/M + S-SWNTs, PVDF/M-SWNTs and PVDF/S-SWNTs membranes. Using Raman scattering, a donor-acceptor interaction is invoked to take place at the interface PVDF/M + S-SWNTs and PVDF/S-SWNTs. In the case of the membranes based on PVDF and M-SWNTs, the changes reported in Raman spectra of the two constituents are explained on the base induction-interaction forces between the permanent dipole of PVDF and induced dipole of M-SWNTs.

  20. Experimental and theoretical comparison of gas desorption energies on metallic and semiconducting single-walled carbon nanotubes.

    Science.gov (United States)

    Mandeltort, Lynn; Chen, De-Li; Saidi, Wissam A; Johnson, J Karl; Cole, Milton W; Yates, John T

    2013-05-22

    Single-walled carbon nanotubes (SWNTs) exhibit high surface areas and precisely defined pores, making them potentially useful materials for gas adsorption and purification. A thorough understanding of the interactions between adsorbates and SWNTs is therefore critical to predicting adsorption isotherms and selectivities. Metallic (M-) and semiconducting (S-) SWNTs have extremely different polarizabilities that might be expected to significantly affect the adsorption energies of molecules. We experimentally and theoretically show that this expectation is contradicted, for both a long chain molecule (n-heptane) and atoms (Ar, Kr, and Xe). Temperature-programmed desorption experiments are combined with van der Waals corrected density functional theory, examining adsorption on interior and exterior sites of the SWNTs. Our calculations show a clear dependence of the adsorption energy on nanotube diameter but not on whether the tubes are conducting or insulating. We find no significant experimental or theoretical difference in adsorption energies for molecules adsorbed on M- and S-SWNTs having the same diameter. Hence, we conclude that the differences in polarizabilities between M- and S-SWNTs have a negligible influence on gas adsorption for spherical molecules as well as for highly anisotropic molecules such as n-heptane. We expect this conclusion to apply to all types of adsorbed molecules where van der Waals interactions govern the molecular interaction with the SWNT.

  1. Crystal and phonon structure of ZnSiP{sub 2}, a II-IV-V{sub 2} semiconducting compound

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Pedraza, H., E-mail: heribertopp@ula.ve [Departamento de Fisica, Universidad de Pamplona, Pamplona 54518000 (Colombia); Lopez-Rivera, S.A.; Martin, J.M. [Laboratorio de Fisica Aplicada, ULA, Merida 5101 (Venezuela, Bolivarian Republic of); Delgado, J.M. [Laboratorio de Cristalografia, ULA, Merida 5101 (Venezuela, Bolivarian Republic of); Power, Ch. [Centro de Estudios en Semiconductores, ULA, Merida 5101 (Venezuela, Bolivarian Republic of)

    2012-09-20

    Using single-crystal X-ray diffraction and Raman spectroscopy, the characterization of a member of the II-IV-V{sub 2} family of semiconducting compounds, ZnSiP{sub 2}, is presented in this work. The diffraction experiment showed that ZnSiP{sub 2} crystallizes in a chalcopyrite-type of structure (space group: I4{sup Macron }2d) with unit cell parameters a = 5.407(9) Angstrom-Sign and c = 10.454(2) Angstrom-Sign . The structure is based on a cubic close-packed arrangement of phosphorus atoms with the two cations in an orderly way occupying one-half of the tetrahedral sites. In this structure, two Zn and two Si are bonded to each phosphorus atom and four phosphorus atoms are bonded to each cation. The results obtained are consistent with previous reports. Raman spectroscopy, Group Theory, and a modified correlation method allowed the assignment of the characteristics of the thirteen first-order Raman active optical vibrational modes observed for this material.

  2. Nanostructured hybrid polymer-inorganic solar cell active layers formed by controllable in situ growth of semiconducting sulfide networks.

    Science.gov (United States)

    Leventis, Henry C; King, Simon P; Sudlow, Anna; Hill, Michael S; Molloy, Kieran C; Haque, Saif A

    2010-04-14

    Nanostructured composites of inorganic and organic materials are attracting extensive interest for electronic and optoelectronic device applications. In this paper, we introduce a general method for the fabrication of metal sulfide nanoparticle/polymer films employing a low-cost and low temperature route compatible with large-scale device manufacturing. Our approach is based upon the controlled in situ thermal decomposition of a solution processable metal xanthate precursor complex in a semiconducting polymer film. To demonstrate the versatility of our method, we fabricate a CdS/P3HT nanocomposite film and show that the metal sulfide network inside the polymer film assists in the absorption of visible light and enables the achievement of high yields of charge photogeneration at the CdS/P3HT heterojunction. Photovoltaic devices based upon such nanocomposite films show solar light to electrical energy conversion efficiencies of 0.7% under full AM1.5 illumination and 1.2% under 10% incident power, demonstrating the potential of such nanocomposite films for low-cost photovoltaic devices.

  3. A theoretical study of the electrical contact between metallic and semiconducting phases in monolayer MoS2

    Science.gov (United States)

    Paz, Wendel S.; Palacios, J. J.

    2017-03-01

    We present a theoretical study of the electrical contact between the two most common crystallographic phases of MoS2 monolayer crystals: the stable semiconducting 2H phase and the metastable metallic 1T phase. A density functional theory (DFT) study of the electronic structure of interface between the two phases shows a higher Schottky barrier for electrons than for holes for the undoped 2H phase. Charge transfer from the 1T to the 2H phase occurs, but, as expected for a one-dimensional contact, the generated dipole potential decays away from the interface and the naive Schottky-Mott band-alignment picture is recovered away from the interface. The decay length of the dipole potential turns out to be larger for the zigzag interface than for the armchair interface due to the different penetration of the edge states into the bulk. Tight-binding quantum transport calculations aided by the DFT results generically confirm a low contact resistance in the range of ≈200-400 Ωμm, as experimentally reported. Furthermore, the contact resistance is predicted to be smaller at the armchair interface for electron injection and, on the contrary, smaller for hole injection at the zigzag interface.

  4. Magnetic and electron-transport properties of spin-gapless semiconducting CoFeCrAl films

    Science.gov (United States)

    Sellmyer, David; Jin, Yunlong; Kharel, Parashu; Valloppilly, Shah; George, Tom; Balasubramanian, Balamurugan; Skomski, Ralph

    Recently, spin-gapless semiconductors (SGS) with a semiconducting or insulating gap in one spin channel and zero gap in the other at the Fermi level have attracted much attention due to their new functionalities such as voltage-tunable spin polarization, the ability to switch between spin-polarized n-type and p-type conduction, high spin polarization and carrier mobility. For the development of spintronic devices utilizing SGS, it is necessary to have a better understanding of the magnetic and transport properties of the thin films of these materials. In this study, the structural, magnetic, and electron-transport properties of a SGS material CoFeCrAl in the thin film geometry have been investigated. CoFeCrAl films were grown on atomically flat SiO2 substrates using magnetron sputtering. The Curie temperature was measured to be 550 K very close to the value reported for bulk CoFeCrAl. Electron-transport measurements on the oriented films revealed a negative temperature coefficient of resistivity, small anomalous Hall conductivity and linear field dependence of magnetoresistance, which are transport signatures of SGS. The effect of elemental compositions and structural ordering on the SGS properties of the CoFeCrAl films will be discussed. Research supported by NSF (Y. J.), DoE (B. B., D. J. S), ARO (T. A. G., S. R. V.), SDSU (P. K.), and NRI (Facilities).

  5. The role of impurities in the shape, structure and physical properties of semiconducting oxide nanostructures grown by thermal evaporation

    Directory of Open Access Journals (Sweden)

    Teresa Cebriano

    2016-03-01

    Full Text Available A thermal evaporation method developed in the research group enables to grow and design several morphologies of semiconducting oxide nanostructures, such as Ga2O3, GeO2 or Sb2O3, among others, and some ternary oxide compounds (ZnGa2O4, Zn2GeO4. In order to tailor physical properties, a successful doping of these nanostructures is required. However, for nanostructured materials, doping may affect not only their physical properties, but also their morphology during the thermal growth process. In this paper, we will show some examples of how the addition of impurities may result into the formation of complex structures, or changes in the structural phase of the material. In particular, we will consider the addition of Sn and Cr impurities into the precursors used to grow Ga2O3, Zn2GeO4 and Sb2O3 nanowires, nanorods or complex nanostructures, such as crossing wires or hierarchical structures. Structural and optical properties were assessed by electron microscopy (SEM and TEM, confocal microscopy, spatially resolved cathodoluminescence (CL, photoluminescence, and Raman spectroscopies. The growth mechanisms, the luminescence bands and the optical confinement in the obtained oxide nanostructures will be discussed. In particular, some of these nanostructures have been found to be of interest as optical microcavities. These nanomaterials may have applications in optical sensing and energy devices.

  6. Synthesis of the p-type semiconducting ternary oxide CuAlO{sub 2} using the Pechini method

    Energy Technology Data Exchange (ETDEWEB)

    Jarman, Richard H., E-mail: Jarman@cod.edu [College of DuPage, 425 Fawell Boulevard, Glen Ellyn, IL 60137-6599 (United States); Bafia, Julie; Gebreslasse, Tsige [College of DuPage, 425 Fawell Boulevard, Glen Ellyn, IL 60137-6599 (United States); Ingram, Brian J.; Carter, J. David [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2013-10-15

    Graphical abstract: - Highlights: • We have prepared single-phase samples of the semiconducting oxide CuAlO{sub 2} using the Pechini method. • Reaction times are reduced relative to conventional solid-state synthesis. • Products have high surface area suitable for ceramic processing. • Product composition is dictated by thermodynamic control; CuAl{sub 2}O{sub 4} is obtained preferentially at lower temperature. - Abstract: The synthesis of the delafossite phase CuAlO{sub 2} using the Pechini method was investigated. Powder X-ray diffraction data showed that pure, single-phase samples were obtained after only 3 h heating at 1100 °C. CuAl{sub 2}O{sub 4}, which contains Cu(II) rather than Cu(I), was the dominant phase between 700 and 1100 °C. Conversion to CuAlO{sub 2} is promoted by the positive entropy change associated with the evolution of oxygen. No mixed Cu–Al oxide was formed below 700 °C.

  7. Rietveld refinement of the semiconducting compound CdGaCrS{sub 4} from X-ray powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, Gerzon E.; Mora, Asiloe J. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Betancourt, Luis; Sagredo, Vicente [Laboratorio de Magnetismo en Solidos, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela)

    2003-10-01

    The semiconducting compound CdGaCrS{sub 4} was refined from an X-ray powder diffraction pattern using the Rietveld method. The X-ray powder pattern was mainly composed of CdGaCrS{sub 4} (88.3%), with CdGa{sub 2}S{sub 4} (9.9%) and Cr{sub 2}S{sub 3} (1.8%) appearing as secondary phases. The CdGaCrS{sub 4} phase crystallizes in the space group Fd-3m (N{sup 0} 227), Z=8, with a=10.1800(3) A, V=1054.98(5) A{sup 3}. The refinement of 28 instrumental and structural parameters led to R{sub p}=9.6 %, R{sub wp}=12.5 %, R{sub exp}=10.5 % and S=1.2. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Discriminating between Metallic and Semiconducting Single-Walled Carbon Nanotubes Using Physisorbed Adsorbates: Role of Wavelike Charge-Density Fluctuations

    Science.gov (United States)

    Gao, Wang; Chen, Yun; Jiang, Qing

    2016-12-01

    Discriminating between metallic (M ) and semiconducting (S ) single-walled carbon nanotubes (SWNTs) remains a fundamental challenge in the field of nanotechnology. We address this issue by studying the adsorption of the isotropic atoms Xe, Kr, and a highly anisotropic molecule n heptane on M - and S -SWNTs with density functional theory that includes many-body dispersion forces. We find that the distinct polarizabilities of M - and S -SWNTs exhibit significantly different physisorption properties, which are also strongly controlled by the SWNT's diameter, adsorption site, adsorbate coverage, and the adsorbate's anisotropy. These findings stem from the wavelike nature of charge-density fluctuations in SWNTs. Particularly, these results allow us to rationalize the unusual √{3 }×√{3 }R 3 00 phase of Kr atoms on small gap M -SWNTs and the double desorption peak temperatures of n heptane on M -SWNTs in experiments, and also propose the n heptane as an effective sensor for experimentally discriminating M - and S -SWNTs.

  9. Radiofrequency electric-field heating behaviors of highly enriched semiconducting and metallic single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Stuart J. Corr[1,2,3; Mustafa Raoof[2,4; Brandon T. Cisneros[2,3,5; Alvin W. Orbaek[3; Matthew A. Cheney[1,2,3; Justin J. Law[1,3; Nadia C. Lara[1,3; Andrew R. Barron[3,6; Lon J. Wilsor[3; Steven A. Curley[1,2,7

    2015-01-01

    It is theorized that enhanced thermal heating may result from exposing single-walled carbon nanotubes (SWNTs) embedded in a conductive host to radiofrequency (RF) electric fields. We examine the RF-induced (13.56 MHz) heating behaviors of 95% metallic- and semiconducting-enriched SWNTs (m-/s-SWNTs) suspended in aqueous solutions with varying NaC1 molarity (0.001 mM-1 M). The heating effects were only evident for host molarities below 1 mM (equivalent to 0.1 S/m) at which the s-SWNT heating rates dominated those of the m-SWNTs. The heating effects were localized to aligned and aggregated "SWNT ropes" -1 cm in length that formed in suspension, parallel to the electric-field vector, during the RF exposure. For molarities above 1 mM, no enhancements were evident, owing to the large heating effects of the bulk ionic NaC1 suspensions, which were observed in previous studies. Although larger enhancement effects proportional to the host conductivity have been theoretically predicted for m-/s-SWNT suspensions, this was not observed most likely because of the aggregation and screening effects, which diminished the scattered electric field near the m-/s-SWNTs. Our research may further the development of better nanoparticle heating agents for applications such as non-invasive RF-induced cancer hyperthermia.

  10. Temperature-dependent thermal conductivities of 1D semiconducting nanowires via four-point-probe 3-ω method.

    Science.gov (United States)

    Lee, Seung-Yong; Lee, Mi-Ri; Park, No-Won; Kim, Gil-Sung; Choi, Heon-Jin; Choi, Tae-Youl; Lee, Sang-Kwon

    2013-12-13

    We report on a systematic study of the thermal transport characteristics of both as-grown zinc oxide and gallium nitride nanowires (NWs) via the four-point-probe 3-ω method in the temperature range 130-300 K. Both as-grown NWs were synthesized by a vapor-liquid-solid growth mechanism, and show clear n-type semiconducting behavior without any defects, which enables both the NWs to be promising candidates for thermoelectric materials. To measure the thermal conductivities of both NWs with lower heat loss and measurement errors, the suspended structures were formed by a combination of an e-beam lithography process and a random dispersion method. The measured thermal conductivities of both NWs are greatly reduced compared to their bulk materials due to the enhanced phonon scattering via the size effect and dopants (impurities). Furthermore, we observed that the Umklapp peaks of both NWs are shifted to a higher temperature than those of their bulk counterparts, indicating that phonon-boundary scattering dominates over other phonon scattering due to the size effect.

  11. Variable range hopping conduction and microstructure properties of semiconducting Co-doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Okutan, Mustafa [Department of Physics, Gebze Institute of Technology, 41400 Gebze (Turkey)]. E-mail: mokutan@gyte.edu.tr; Bakan, Halil I. [TUBITAK-MAM, Materials and Chemical Research Institute, 41470 Gebze (Turkey); Korkmaz, Kemal [Department of Material Science and Engineering, Gebze Institute of Technology, 41400 Gebze (Turkey); Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Arts and Science, Firat University, 23169 Elazig (Turkey)

    2005-01-31

    The surface morphology, phases existing in the microstructure and conductivity behavior of Co-doped TiO2 have been investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), electrical conductivity measurements and X-ray diffraction technique. The semiconducting phase is found to obey Mott's variable range hopping mechanism of the conduction. The conduction mechanism of the ceramic shows a crossover from the, exp[-(T0/T)1/4] law to a simply activated law, exp(-{delta}E/kT). This behavior is attributed to temperature-induced transition from 3D to thermally activated behavior. The hopping conduction parameters such as the characteristic temperature (T0), localization length ({alpha}), hopping distance (R), activation energy ({delta}E) and density of states at Fermi level (N(EF) have been calculated. Surface morphology shows that the ceramic has a regular surface. The SEM study indicates that there are grains which have a certain type in the microstructure. Rutile phases with different plane in microstructure were found.

  12. Lateral bending of tapered piezo-semiconductive nanostructures for ultra-sensitive mechanical force to voltage conversion.

    Science.gov (United States)

    Araneo, Rodolfo; Falconi, Christian

    2013-07-05

    Quasi-1D piezoelectric nanostructures may offer unprecedented sensitivity for transducing minuscule input mechanical forces into high output voltages due to both scaling laws and increased piezoelectric coefficients. However, until now both theoretical and experimental studies have suggested that, for a given mechanical force, lateral bending of piezoelectric nanowires results in lower output electric potentials than vertical compression. Here we demonstrate that this result only applies to nanostructures with a constant cross-section. Moreover, though it is commonly believed that the output electric potential of a strained piezo-semiconductive device can only be reduced by the presence of free charges, we show that the output piezopotential of laterally bent tapered nanostructures, with typical doping levels and very small input forces, can be even increased up to two times by free charges.Our analyses confirm that, though not optimal for piezoelectric energy harvesting, lateral bending of tapered nanostructures with typical doping levels can be ideal for transducing tiny input mechanical forces into high and accessible piezopotentials. Our results provide guidelines for designing high-performance piezo-nano-devices for energy harvesting, mechanical sensing, piezotronics, piezo-phototronics, and piezo-controlled chemical reactions, among others.

  13. Tunable Light Filtering in a Bragg Mirror/Heavily-Doped Semiconducting Nanocrystal Composite

    CERN Document Server

    Kriegel, Ilka

    2014-01-01

    Tunable light filters are critical components for many optical applications in which light in-coupling, out-coupling or rejection is crucial, such as lasing, sensing, photovoltaics and information and communication technology. For this purpose, Bragg mirrors, band-pass filters with high reflectivity represent good candidates. However, their optical characteristics are determined at the stage of fabrication. Heavily doped semiconductor nanocrystals (NCs) on the other hand deliver a high degree of optical tunability through the active modulation of their carrier density ultimately influencing their plasmonic absorption properties. Here, we propose the design of a tunable light filter composed of a Bragg mirror and a layer of plasmonic semiconductor NCs. We demonstrate that the filtering properties of the coupled device can be tuned to cover a wide range of frequencies from the visible to the near infrared (vis-NIR) spectral region when employing varying carrier densities. As tunable component we implemented a d...

  14. Import vs. Imitation?

    DEFF Research Database (Denmark)

    Kölcze, Zsófia

    2012-01-01

    of our analysis and interpretation more explicit.In archaeology there has been a tradition of distinguishing between original objects and imitations. However, this distinction does not provide us with much information about the social function and symbolic meaning of an object in a cultural context......In recent years archaeological research has developed a radically new theoretical approach to prehistoric material culture. Objects are no longer regarded as simple products of human behavior, but rather as agents interacting with people on multiple levels. As such, artifacts play an active role...... in producing, maintaining and reproducing social identities, communicating new ideas and technological innovations and creating ideologies and cosmologies. Our understanding of material culture has obtained a social dimension, and we as archaeologists have become aware of the importance of making this aspect...

  15. Progress in the development of semiconducting metal oxide gas sensors: a review

    Science.gov (United States)

    Moseley, Patrick T.

    2017-08-01

    Since the first suggestion, during the 1950s, that high-surface-area metal oxides could be used as conductometric gas sensors enormous efforts have been made to enhance both the selectivity and the sensitivity of such devices, and to reduce their operational power requirements. This development has involved the exploration of response mechanisms, the selection of the most appropriate oxide compositions, the fabrication of two-phase ‘hetero-structures’, the addition of metallic catalyst particles and the optimisation of the manner in which the materials are presented to the gas—the structure and the nanostructure of the sensing elements. Far more of the scientific literature has been devoted to seeking such improvements in metal oxide gas sensors than has been directed at all other solid-state gas sensors together. Recent progress in the research and development of metal oxide gas sensor technology is surveyed in this invited review. The advances that have been made are quite spectacular and the results of individual pieces of work are drawn together here so that trends can be seen. Emerging features include: the significance of n-type/p-type switching, the enhancement of sensing performance of materials through the incorporation of secondary components and the advantages of interrogating sensors with alternating current rather than direct current.

  16. Semiconducting:insulating polymer blends for optoelectronic applications—a review of recent advances

    KAUST Repository

    Scaccabarozzi, A. D.

    2014-01-01

    In recent years, immense efforts in the organic electronics field have led to unprecedented progress and to devices of ever increasing performance. Despite these advances, new opportunities are sought in order to widen the applications of organic-based technologies and expand their functionalities and features. For this purpose, use of multicomponent systems seems an interesting approach in view of, e.g., increasing the mechanical flexibility and stability of organic electronic products as well as introducing other features such as self-encapsulation. One specific strategy is based on blending polymeric insulators with organic semiconductors; which has led to a desired improvement of the mechanical properties of organic devices, producing in certain scenarios robust and stable architectures. Here we discuss the working principle of semiconductor:insulator blends, examining the different approaches that have recently been reported in literature. We illustrate how organic field-effect transistors (OFET)s and organic solar cells (OPV)s can be fabricated with such systems without detrimental effects on the resulting device characteristics even at high contents of the insulator. Furthermore, we review the various properties that can be enhanced and/or manipulated by blending including air stability, mechanical toughness, H- vs. J-aggregation, etc. This journal is © the Partner Organisations 2014.

  17. The Most Important Maglev Applications

    Directory of Open Access Journals (Sweden)

    Hamid Yaghoubi

    2013-01-01

    Full Text Available The name maglev is derived from magnetic levitation. Magnetic levitation is a highly advanced technology. It has various uses. The common point in all applications is the lack of contact and thus no wear and friction. This increases efficiency, reduces maintenance costs, and increases the useful life of the system. The magnetic levitation technology can be used as an efficient technology in the various industries. There are already many countries that are attracted to maglev systems. Many systems have been proposed in different parts of the worlds. This paper tries to study the most important uses of magnetic levitation technology. The results clearly reflect that the maglev can be conveniently considered as a solution for the future engineering needs of the world.

  18. Red long lasting phosphorescence of Eu3+ doped BiOCl semiconducting polycrystals

    Institute of Scientific and Technical Information of China (English)

    周玉婷; 宋志国; 李永进; 刘群; 徐祖元; 胡锐; 张相周; 邱建备; 杨正文

    2016-01-01

    The exploration of novel long lasting red phosphors is still of importance due to expected commercial applications and scientific interests. In this work, we reported the red long lasting phosphorescence (LLP) from Eu3+ doped BiOCl semiconductor polycrystals. The LLP property of the red phosphor is relatively weak due to less trap density, but the excitation band of LLP stems from the energy gap transition of semiconductor, offering experimental evidence for energy transfer between BiOCl semiconductor and Eu3+ ions. Although the afterglow duration of Eu3+ doped BiOCl was short temporarily, this work may open a novel kind of red LLP phosphors.

  19. Tunable light filtering by a Bragg mirror/heavily doped semiconducting nanocrystal composite

    Directory of Open Access Journals (Sweden)

    Ilka Kriegel

    2015-01-01

    Full Text Available Tunable light filters are critical components for many optical applications in which light in-coupling, out-coupling or rejection is crucial, such as lasing, sensing, photovoltaics and information and communication technology. For this purpose, Bragg mirrors (band-pass filters with high reflectivity represent good candidates. However, their optical characteristics are determined during the fabrication stage. Heavily doped semiconductor nanocrystals (NCs, on the other hand, deliver a high degree of optical tunability through the active modulation of their carrier density, ultimately influencing their plasmonic absorption properties. Here, we propose the design of an actively tunable light filter composed of a Bragg mirror and a layer of plasmonic semiconductor NCs. We demonstrate that the filtering properties of the coupled device can be tuned to cover a wide range of frequencies from the visible to the near infrared (vis–NIR spectral region when employing varying carrier densities. As the tunable component, we implemented a dispersion of copper selenide (Cu2−xSe NCs and a film of indium tin oxide (ITO NCs, which are known to show optical tunablility with chemical or electrochemical treatments. We utilized the Mie theory to describe the carrier-dependent plasmonic properties of the Cu2−x Se NC dispersion and the effective medium theory to describe the optical characteristics of the ITO film. The transmission properties of the Bragg mirror have been modelled with the transfer matrix method. We foresee ease of experimental realization of the coupled device, where filtering modulation is achieved upon chemical and electrochemical post-fabrication treatment of the heavily doped semiconductor NC component, eventually resulting in tunable transmission properties of the coupled device.

  20. Tunable light filtering by a Bragg mirror/heavily doped semiconducting nanocrystal composite.

    Science.gov (United States)

    Kriegel, Ilka; Scotognella, Francesco

    2015-01-01

    Tunable light filters are critical components for many optical applications in which light in-coupling, out-coupling or rejection is crucial, such as lasing, sensing, photovoltaics and information and communication technology. For this purpose, Bragg mirrors (band-pass filters with high reflectivity) represent good candidates. However, their optical characteristics are determined during the fabrication stage. Heavily doped semiconductor nanocrystals (NCs), on the other hand, deliver a high degree of optical tunability through the active modulation of their carrier density, ultimately influencing their plasmonic absorption properties. Here, we propose the design of an actively tunable light filter composed of a Bragg mirror and a layer of plasmonic semiconductor NCs. We demonstrate that the filtering properties of the coupled device can be tuned to cover a wide range of frequencies from the visible to the near infrared (vis-NIR) spectral region when employing varying carrier densities. As the tunable component, we implemented a dispersion of copper selenide (Cu2-xSe) NCs and a film of indium tin oxide (ITO) NCs, which are known to show optical tunablility with chemical or electrochemical treatments. We utilized the Mie theory to describe the carrier-dependent plasmonic properties of the Cu2-x Se NC dispersion and the effective medium theory to describe the optical characteristics of the ITO film. The transmission properties of the Bragg mirror have been modelled with the transfer matrix method. We foresee ease of experimental realization of the coupled device, where filtering modulation is achieved upon chemical and electrochemical post-fabrication treatment of the heavily doped semiconductor NC component, eventually resulting in tunable transmission properties of the coupled device.

  1. SERS of semiconducting nanoparticles (TiO{sub 2} hybrid composites).

    Energy Technology Data Exchange (ETDEWEB)

    Musumeci, A.; Gosztola, D.; Schiller, T.; Dimitrijevic, N.; Mujica, V.; Martin, D.; Rajh, T. (Center for Nanoscale Materials)

    2009-04-13

    Raman scattering of molecules adsorbed on the surface of TiO{sub 2} nanoparticles was investigated. We find strong enhancement of Raman scattering in hybrid composites that exhibit charge transfer absorption with TiO{sub 2} nanoparticles. An enhancement factor up to {approx}10{sup 3} was observed in the solutions containing TiO{sub 2} nanoparticles and biomolecules, including the important class of neurotransmitters such as dopamine and dopac (3,4-dihydroxy-phenylacetic acid). Only selected vibrations are enhanced, indicating molecular specificity due to distinct binding and orientation of the biomolecules coupled to the TiO{sub 2} surface. All enhanced modes are associated with the asymmetric vibrations of attached molecules that lower the symmetry of the charge transfer complex. The intensity and the energy of selected vibrations are dependent on the size and shape of nanoparticle support. Moreover, we show that localization of the charge in quantized nanoparticles (2 nm), demonstrated as the blue shift of particle absorption, diminishes SERS enhancement. Importantly, the smallest concentration of adsorbed molecules shows the largest Raman enhancements suggesting the possibility for high sensitivity of this system in the detection of biomolecules that form a charge transfer complex with metal oxide nanoparticles. The wavelength-dependent properties of a hybrid composite suggest a Raman resonant state. Adsorbed molecules that do not show a charge transfer complex show weak enhancements probably due to the dielectric cavity effect.

  2. 信息化条件下医院医学摄影(像)专业的重要作用%Importance of Medical Photography and Videography in Context of Information Technology

    Institute of Scientific and Technical Information of China (English)

    陈玲; 张向阳; 陈敏; 靳红岩

    2012-01-01

    Objective To explore how the medical photography and videography to do in order to meet the new requirement and provide professional support to medical service in the context of information technology. Methods Research and analysis were made on the professional characteristics of and the main tasks fulfilled by the medical photography and videography in the hospital. Results Medical photography and videography had become an integral part of the medical treatment and education and played an important role in the hospital development. Conclusion People involved in medical photography and videography have to be creative, proactively extend their work and service, and play a role in the medical education, they also have to take advantage of their profession and provide professional support to the medical service of the hospital by means of, for instance, maintaining a perfect Website, playing a multi-functional part and being a cross-function doctor. [Chinese Medical Equipment Journal,2011,33(3) :89-91]%目的:探讨信息化条件下医院医学摄影(像)专业如何适应新的形势任务需求,开展好专业化服务保障工作.方法:对医院医学摄影(像)专业自身特点和所承担的主要任务进行梳理、分析和研究.结果:医学摄影(像)专业工作 已同医院医教研工作以及医院全面建设紧密联系.结论:医院医学摄影(像)专业必须创新思维,主动作为,扩展工作和服务范围,配合医院重大工作做好专业化服务保障,搞好医院门户网站建设,担当好“多面手”及“全科医生”.

  3. Enhanced H2S Sensing Performance of a p-type Semiconducting PdO-NiO Nanoscale Heteromixture

    Science.gov (United States)

    Balamurugan, C.; Jeong, Y. J.; Lee, D. W.

    2017-10-01

    Semiconducting nanocrystalline nickel oxide (NiO) and PdO-doped NiO heteromixture (2, 5 and 10 wt%) have been synthesized via a metal-citrate complex method. The obtained materials were further characterized using TG/DTA, FT-IR, UV-vis, XRD, XPS, BET/BJH, SEM and TEM analyses to determine their structural and morphological properties. The results indicated that the spherical, uniform PdO nanoparticles were densely deposited on the NiO surface mainly in diameters of 10-15 nm. Moreover, the existence of various defect states was also analyzed with the help of photoluminescence (PL) spectroscopy. The gas response characteristics of synthesized materials were evaluated in the presence and absence of toxic gases such as hydrogen sulfide (H2S), carbon monoxide (CO), liquid petroleum gas (LPG), and ethanol (C2H5OH). The experimental results revealed that the sensitivity and selectivity of the NiO-based sensor material are dependent on the weight% of PdO loading in the NiO nanopowder. Among the investigated compound, the 5 wt% PdO-doped NiO sensor material showed excellent sensitivity and selectivity to 100 ppm H2S with a fast response/recovery characteristics of 6 s and 10 s, respectively. Furthermore, the 5 wt% PdO-doped NiO based sensor showed a linear relationship between the different concentrations of H2S gas and a significantly higher response to H2S even at the low concentration of 20 ppm (43%) at 60 °C. The dominant H2S gas sensing mechanisms in the NiO and 5 wt% PdO-doped NiO nanomaterials are systematically discussed based on the obtained characterization results.

  4. Characterization of phase structures in semiconducting SnWO4 powders by Mössbauer and Raman spectroscopies

    Science.gov (United States)

    Solis, J. L.; Frantti, J.; Lantto, V.; Häggström, L.; Wikner, M.

    1998-06-01

    Stannous tungstate, SnWO4, crystallizes in the low-temperature α and high-temperature β phases. α-SnWO4 powders were prepared by heating an equimolar mixture of SnO and WO3 either in vacuum or in argon atmosphere at 600 °C for 15 h. The high-temperature β phase was obtained as metastable at room temperature after heating the mixture at 800 °C and rapid quenching. In addition to x-ray-diffraction studies, 119Sn Mössbauer and Raman spectroscopies were used as ``local'' probes for the characterization of the phase structures in the semiconducting and gas-sensitive powders. The composition of the powders was measured by the energy-dispersive spectroscopy of x rays. Mössbauer spectroscopy, especially, as a very local probe for tin atoms gave valuable information of small extra phase(s) in the α- and β-SnWO4 powders originating in the oxidation of Sn2+ ions in the SnWO4 structures into the Sn4+ form. The Sn2+ Mössbauer doublet from both α and β phases showed some asymmetry not published before. The asymmetry was possible to relate to the Goldanskii-Karyagin effect with calculations based on published results for the atomic positions and thermal displacement parameters in the x-ray temperature factor of the α- and β-SnWO4 structures. Raman spectra are given together with peak frequencies from a curve fit for both α- and β-phase powders. The symmetries and selection rules of the normal modes at the center of the Brillouin zone are also given for both α and β phases.

  5. Enhancement of Photoluminescence from Semiconducting Nanotubes in Aqueous Suspensions due to Cysteine and Dithiothreitol Doping: Influence of the Sonication Treatment.

    Science.gov (United States)

    Kurnosov, Nikita V; Leontiev, Victor S; Karachevtsev, Victor A

    2016-12-01

    The influence of tip sonication duration on the spectral characteristics of carbon single-walled nanotubes (SWNTs) in aqueous suspension with single-stranded DNA (ssDNA) has been studied by NIR luminescence, NIR absorption, and Raman spectroscopy. It was revealed that prolongation of sonication leads to weakening of the SWNT polymer coverage and appearance of additional defects on the nanotube surface. Prolongation of the tip sonication treatment of SWNT/ssDNA from 30 to 90 min leads to the increase of the number of individual nanotubes in the aqueous suspension, but it significantly decreases the photoluminescence (PL) from semiconducting SWNTs because more defects are formed on the nanotube surface. At probing the SWNT/ssDNA emission with cysteine or dithiothreitol (DTT) doping the nanotube aqueous suspension showed the different PL intensity enhancement depending on the duration of the sonication treatment and on the ability of these reducing agents to passivate emission-quenching defects on the carbon nanotube sidewall. The magnitude of the PL enhancement rises with sonication prolongation and depends on the nanotube chirality. Tight and ordered polymer coverage of (6,4) nanotubes hampers the access of the reducing agent to emission-quenching defects on the nanotube surface and provides the weaker PL intensity increasing while (7,5) nanotubes show the strongest reaction to the doping effect. The comparison of cysteine and DTT ability to passivate the emission-quenching defects showed the higher efficiency of DTT doping. This prevailing is explained by the stronger reducing activity of DTT which is determined by a lower redox potential of this molecule.

  6. Enhancement of Photoluminescence from Semiconducting Nanotubes in Aqueous Suspensions due to Cysteine and Dithiothreitol Doping: Influence of the Sonication Treatment

    Science.gov (United States)

    Kurnosov, Nikita V.; Leontiev, Victor S.; Karachevtsev, Victor A.

    2016-11-01

    The influence of tip sonication duration on the spectral characteristics of carbon single-walled nanotubes (SWNTs) in aqueous suspension with single-stranded DNA (ssDNA) has been studied by NIR luminescence, NIR absorption, and Raman spectroscopy. It was revealed that prolongation of sonication leads to weakening of the SWNT polymer coverage and appearance of additional defects on the nanotube surface. Prolongation of the tip sonication treatment of SWNT/ssDNA from 30 to 90 min leads to the increase of the number of individual nanotubes in the aqueous suspension, but it significantly decreases the photoluminescence (PL) from semiconducting SWNTs because more defects are formed on the nanotube surface. At probing the SWNT/ssDNA emission with cysteine or dithiothreitol (DTT) doping the nanotube aqueous suspension showed the different PL intensity enhancement depending on the duration of the sonication treatment and on the ability of these reducing agents to passivate emission-quenching defects on the carbon nanotube sidewall. The magnitude of the PL enhancement rises with sonication prolongation and depends on the nanotube chirality. Tight and ordered polymer coverage of (6,4) nanotubes hampers the access of the reducing agent to emission-quenching defects on the nanotube surface and provides the weaker PL intensity increasing while (7,5) nanotubes show the strongest reaction to the doping effect. The comparison of cysteine and DTT ability to passivate the emission-quenching defects showed the higher efficiency of DTT doping. This prevailing is explained by the stronger reducing activity of DTT which is determined by a lower redox potential of this molecule.

  7. Optical properties of dy doped lead and bismuth borate glasses - effect of glass composition, metal and semiconducting nanoparticles

    Science.gov (United States)

    Ooi, Hio Giap

    The optical properties of Dy3+ ions in lead borate and bismuth borate glasses are studied as a function of glass composition with PbO content (29.5 to 69.5mol%) and Bi2O3 content (29.5 to 59.5 mol%). We also studied the effect of metal and semiconducting nanoparticles on the absorption and fluorescence emission of Dy3+ ions in both lead and bismuth borate glasses. The absorption coefficient at each wavelength is obtained from the optical absorption spectrum of a glass sample, and the number density of rare-earth (RE) ions is calculated from the measurement of the glass density. These two parameters are then used to calculate the oscillator strength of each transition using Judd-Ofelt theory. Using the oscillator strength for each transition, we obtained the intensity parameters which represent changes in the symmetry of the ligand field at the Dy 3+ site (due to structural group changes and changes in Dy-O covalency). Radiative transition probabilities, the radiative lifetime of the excited states and the branching ratios are then obtained from these intensity parameters. The fluorescence spectra, obtained using 355 nm and 458 nm laser excitation, are analyzed by determining the area ratio of yellow/blue (Y/B) peaks and the wavelength of the hypersensitive transition (HST). The compositional dependence and effect of nanoparticles on the stimulated emission cross-section (sigmap), are then evaluated using radiative transition probability, the refractive index of the host glass, effective fluorescence linewidth, and the position of the band. In all of the glass systems, it was found that the optical properties are strongly influenced by structural changes arising from compositional variation and size of nanoparticles. Dy 3+ transitions exhibit large sigmap suggesting the possible utilization of these materials in laser applications.

  8. Photoelectrochemistry, Electronic Structure, and Bandgap Sizes of Semiconducting Cu(I)-Niobates and Cu(I)-Tantalates

    Energy Technology Data Exchange (ETDEWEB)

    Maggard, Paul A.

    2013-11-14

    Semiconducting metal-oxides have remained of intense research interest owing to their potential for achieving efficient solar-driven photocatalytic reactions in aqueous solutions that occur as a result of their bandgap excitation. The photocatalytic reduction of water or carbon dioxide to generate hydrogen or hydrocarbon fuels, respectively, can be driven on p-type (photocathodic) electrodes with suitable band energies. However, metal-oxide semiconductors are typically difficult to dope as p-type with a high mobility of carriers. The supported research led to the discovery of new p-type Cu(I)-niobate and Cu(I)-tantalate film electrodes that can be prepared on FTO glass. New high-purity flux syntheses and the full structural determination of several Cu(I)-containing niobates and tantalates have been completed, as well as new investigations of their optical and photoelectrochemical properties and electronic structures via density-functional theory calculations. For example, CuNbO3, Cu5Ta11O30 and CuNb3O8 were prepared in high purity and their structures were characterized by both single-crystal and powder X-ray diffraction techniques. These two classes of Cu(I)-containing compounds exhibit optical bandgap sizes ranging from ~1.3 eV to ~2.6 eV. Photoelectrochemical measurements of these compounds show strong photon-driven cathodic currents that confirm the p-type semiconductor behavior of CuNbO3, CuNb3O8, and Cu5Ta11O30. Incident-photon-to-current efficiencies are measured that approach greater than ~1%. Electronic-structure calculations based on density functional theory reveal the visible-light absorption stems from a nearly-direct bandgap transition involving a copper-to-niobium or tantalum (d10 to d0) charge-transfer excitations.

  9. Fabrication Technology

    Energy Technology Data Exchange (ETDEWEB)

    Blaedel, K.L.

    1993-03-01

    The mission of the Fabrication Technology thrust area is to have an adequate base of manufacturing technology, not necessarily resident at Lawrence Livermore National Laboratory (LLNL), to conduct the future business of LLNL. The specific goals continue to be to (1) develop an understanding of fundamental fabrication processes; (2) construct general purpose process models that will have wide applicability; (3) document findings and models in journals; (4) transfer technology to LLNL programs, industry, and colleagues; and (5) develop continuing relationships with the industrial and academic communities to advance the collective understanding of fabrication processes. The strategy to ensure success is changing. For technologies in which they are expert and which will continue to be of future importance to LLNL, they can often attract outside resources both to maintain their expertise by applying it to a specific problem and to help fund further development. A popular vehicle to fund such work is the Cooperative Research and Development Agreement with industry. For technologies needing development because of their future critical importance and in which they are not expert, they use internal funding sources. These latter are the topics of the thrust area. Three FY-92 funded projects are discussed in this section. Each project clearly moves the Fabrication Technology thrust area towards the goals outlined above. They have also continued their membership in the North Carolina State University Precision Engineering Center, a multidisciplinary research and graduate program established to provide the new technologies needed by high-technology institutions in the US. As members, they have access to and use of the results of their research projects, many of which parallel the precision engineering efforts at LLNL.

  10. Fabrication Technology

    Energy Technology Data Exchange (ETDEWEB)

    Blaedel, K.L.

    1993-03-01

    The mission of the Fabrication Technology thrust area is to have an adequate base of manufacturing technology, not necessarily resident at Lawrence Livermore National Laboratory (LLNL), to conduct the future business of LLNL. The specific goals continue to be to (1) develop an understanding of fundamental fabrication processes; (2) construct general purpose process models that will have wide applicability; (3) document findings and models in journals; (4) transfer technology to LLNL programs, industry, and colleagues; and (5) develop continuing relationships with the industrial and academic communities to advance the collective understanding of fabrication processes. The strategy to ensure success is changing. For technologies in which they are expert and which will continue to be of future importance to LLNL, they can often attract outside resources both to maintain their expertise by applying it to a specific problem and to help fund further development. A popular vehicle to fund such work is the Cooperative Research and Development Agreement with industry. For technologies needing development because of their future critical importance and in which they are not expert, they use internal funding sources. These latter are the topics of the thrust area. Three FY-92 funded projects are discussed in this section. Each project clearly moves the Fabrication Technology thrust area towards the goals outlined above. They have also continued their membership in the North Carolina State University Precision Engineering Center, a multidisciplinary research and graduate program established to provide the new technologies needed by high-technology institutions in the US. As members, they have access to and use of the results of their research projects, many of which parallel the precision engineering efforts at LLNL.

  11. The importance of the technology variable in the public policies for the public electric sector; A importancia da variavel tecnologica no contexto das politicas publicas para setor eletrico brasileiro - SEB

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Valcir dos Reis [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Planejamento Energetico; Furtado, Andre Tosi [Universidade Estadual de Campinas, SP (Brazil). Inst. de Geociencias. Dept. de Politica Cientifica e Tecnologica

    1998-12-31

    In this article we analyze the institutional and the organizational changes of Brazilian Electric Sector - BES at the light of world technological and institutional transformations. Firstly, we show a panorama of the main changes in the directives of central countries energy policies and the technological evolution of electrical industry. Afterwards, we analyze the relationships between these two levels of change and the regulation process in this industry. Finally we analyze the two levels of the public policies that sustains the institutionalization of the activities of the BES. The first one, involves the wider measures of industrial and technological policy of the country; while the second one is about the current process of institutional changes. (author) 20 refs.; e-mail: valcir at ppe.ufrj.br; furtado at ige.unicamp.br

  12. To Enhance Information Literacy:an Important Goal of Information Technology Education in Primary and Secondary Schools%提升信息素养:中小学信息技术教育的重要目标

    Institute of Scientific and Technical Information of China (English)

    武怀生; 李秀明

    2013-01-01

    In this paper, through the analysis of the current information technology education in primary and secondary schools is behind the prosperity from the series of problems in the interpretation of meaning, and the extension of information technology cur?riculum guidelines and standards in primary and secondary schools, to explore information technology education to promote the stu?dents' information literacy theory support and the practice path.%该文通过分析当前中小学信息技术教育的繁荣背后从在的系列问题,解读中小学信息技术课程纲要和标准的内涵与外延,探索通过信息技术教育来提升学生信息素养的理论支持和实践途径.

  13. Probing the degradation and homogeneity of embedded perovskite semiconducting layers in photovoltaic devices by Raman spectroscopy.

    Science.gov (United States)

    Hooper, K E A; Lee, H K H; Newman, M J; Meroni, S; Baker, J; Watson, T M; Tsoi, W C

    2017-02-15

    The key challenges for perovskite solar cells include their poor stability and film homogeneity. Studying the degradation and homogeneity of perovskite layers within device structures can be challenging but critical to the understanding of stability and effect of processing in real life conditions. We show that Raman spectroscopy (RS) is a unique and powerful method (simple and fast) to probe the degradation of the perovskite film within the device structure and image perovskite formation. We demonstrate that RS can be used to directly probe chemical (PbI2) and physical (dihydrated phase) degradation of a perovskite film, and estimate the relative amount of the degradation species formed, mapping its distribution with ∼1 μm spatial resolution. This has been applied to mapping a large area perovskite module to characterise the efficacy of PbI2 to perovskite conversion. We also use RS to study the degradation species and kinetics under diverse accelerated degradation conditions (temperature and humidity) in situ. These capabilities are difficult to achieve with other methods, presenting RS as an important tool to gain understanding of the degradation and effect of processing on perovskite-based photovoltaic devices.

  14. Characterization of the charge transport and electrical properties in solution-processed semiconducting polymers

    Institute of Scientific and Technical Information of China (English)

    WANG LiGuo; ZHANG HuaiWu; TANG XiaoLi; LI YuanXun; ZHONG ZhiYong

    2012-01-01

    The conventional charge transport models based on density- and field-dependent mobility,only having a non-Arrhenius temperature dependence,cannot give good current-voltage characteristics of poly (2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) hole-only devices.In this paper,we demonstrate that the current-voltage characteristics can give a good unified description of the temperature,carrier density and electric field dependence of mobility based on both the Arrhenius temperature dependence and the non-Arrhenius temperature dependence.Furthermore,we perform a systematic study of charge transport and electrical properties for MEH-PPV.It is shown that the boundary carrier density has an important effect on the current-voltage characteristics.Too large or too small values of boundary carder density will lead to incorrect current-voltage characteristics.The numerically calculated carrier density is a decreasing function of the distance to the interface,and the numerically calculated electric field is an increasing function of the distance.Both the maximum of carrier density and the minimum of electric field appear near the interface.

  15. Imaging surface acoustic wave dynamics in semiconducting polymers by scanning ultrafast electron microscopy.

    Science.gov (United States)

    Najafi, Ebrahim; Liao, Bolin; Scarborough, Timothy; Zewail, Ahmed

    2017-08-24

    Understanding the mechanical properties of organic semiconductors is essential to their electronic and photovoltaic applications. Despite a large volume of research directed toward elucidating the chemical, physical and electronic properties of these materials, little attention has been directed toward understanding their thermo-mechanical behavior. Here, we report the ultrafast imaging of surface acoustic waves (SAWs) on the surface of the Poly(3-hexylthiophene-2,5-diyl) (P3HT) thin film at the picosecond and nanosecond timescales. We then use these images to measure the propagation velocity of SAWs, which we then employ to determine the Young's modulus of P3HT. We further validate our experimental observation by performing a semi-empirical transient thermoelastic finite element analysis. Our findings demonstrate the potential of ultrafast electron microscopy to not only probe charge carrier dynamics in materials as previously reported, but also to measure their mechanical properties with great accuracy. This is particularly important when in situ characterization of stiffness for thin devices and nanomaterials is required. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Probing the interface between semiconducting nanocrystals and molecular metal chalcogenide surface ligands: insights from first principles

    Science.gov (United States)

    Scalise, Emilio; Wippermann, Stefan; Galli, Giulia; Talapin, Dmitri

    Colloidal nanocrystals (NCs) are emerging as cost-effective materials offering exciting prospects for solar energy conversion, light emission and electronic applications. Recent experimental advances demonstrate the synthesis of fully inorganic nanocrystal solids from chemical solution processing. The properties of the NC-solids are heavily determined by the NCs surface and their interactions with the host matrix. However, information on the atomistic structure of such composites is hard to obtain, due to the complexity of the synthesis conditions and the unavailability of robust experimental techniques to probe nanointerfaces at the microscopic level. Here we present a systematic theoretical study of the interaction between InAs and InP NCs with Sn2S64- ligands. Employing a grand canonical ab initio thermodynamic approach we investigate the relative stability of a multitude of configurations possibly realized at the NC-ligand interface. Our study highlights the importance of different structural details and their strong impact on the resulting composite's properties. We show that to obtain a detailed understanding of experimental data it is necessary to take into account complex interfacial structures beyond simplified NC-ligand model interfaces. S. W. acknowledges BMBF NanoMatFutur Grant No. 13N12972. G.G. acknowledges DOE-BES for funding part of this work.

  17. Transport and dielectric studies of metallic, semiconducting, and magnetic materials and devices

    Science.gov (United States)

    Vasic, Relja

    Several organic and inorganic systems of importance for fundamental physics and applications have been studied by magnetotransport, dielectric constant, and Raman spectroscopy techniques. At the beginning of my thesis work, I investigated three carbon based organic systems: carbon fibers, pentacene derivatives, and a nanomagnetic material ("V15"). In the latter stages of my dissertation, I used the techniques I had developed to explore the properties of two inorganic systems: NiFe nanopillars in a silicon matrix, and spin systems in multiferroic rare earth-transition metal oxides. The main activities and achievements of my thesis work are as follows: The carbon fibers were characterized by magnetotransport and Raman spectroscopy studies. I found that carbon fibers are promising as wires in molecular electronics and compatible with organic films. Preliminary results on simple films of melted pentacene derivatives connected with carbon fiber wires were a first step in the fabrication and characterization of pentacene field effect transistors (FET's). The work on the pentacene system resulted in a series of successful logic circuits based on field-effect transistors such as NOT (inverter), NOR, and NAND. The temperature-dependent mobility was described as thermally activated at low gate voltages, but at high gate voltages the mobility was enhanced due to shallow traps. The second system investigated was the organic nanomagnetic material, polyoxovanadate, K6[V15As6O42(H 2O)]˙8H2O (i.e. V15). The conductivity and the dielectric measurements at high and low temperatures respectively were used to determine electrical properties of this single magnet molecule system. The main accomplishments were the determination of the energy gap (0.2eV) and the identification of multiple dipole relaxation modes. Raman vibrational spectroscopy was used to correlate dielectric relaxation with the Raman intramolecular vibrations. An investigation was then carried out on NiFe nanopillars

  18. `Technology for Advanced Treatment of High Melting Point Metal-Based Material,` local research and development of important technology for fiscal 1997. Development of materials creation technology for high efficiency power generator components; 1997 nendo juyo chiiki gijutsu kenkyu kaihatsu. `Koyuten kinzokukei buzai no kodo kako gijutsu` (kokoritsu hatsuden`yo buzai sosei gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Efforts are made for the creation of high melting point metal-base materials to replace the currently-used Ni-base superalloys for the turbine to withstand higher operating temperatures. The main efforts made in fiscal 1997 are outlined. As in fiscal 1996, Nb-base solution alloys, in which solution reinforcement elements such as Mo and W are alloyed, are manufactured by button arc melting and tested for mechanical properties and texture/characteristics. In the designing and evaluation for a strongest Nb-base composite material, Nb-base composite materials are manufactured by use of particle dispersion-strengthening attained by addition of intermetallic compounds or elements to contribute to the formation of oxides, carbides, or nitrides. Nb-base composite materials may also be manufactured by use of eutectic-strengthening attained by utilizing crystallization in the process of coagulation. The resultant Nb-base composite materials are evaluated for their dynamic characteristics at high temperatures. In the development and evaluation of technologies for creating Nb-base materials for high-temperature components, larger specimens as heavy as several kg are tested in line with small specimens for basic studies, and the results are utilized for alloy designing for high-temperature materials. 50 refs., 97 figs., 15 tabs.

  19. Is there a Difference in Van Der Waals Interactions between Rare Gas Atoms Adsorbed on Metallic and Semiconducting Single-Walled Carbon Nanotubes?

    Energy Technology Data Exchange (ETDEWEB)

    Chen, De-Li [Univ. of Pittsburgh, PA (United States). Dept. of Chemical and Petroleum Engineering; Mandeltort, Lynn [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Chemistry; Saidi, Wissam A. [Univ. of Pittsburgh, PA (United States). Dept. of Chemical and Petroleum Engineering; Yates, John T. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Chemistry; Cole, Milton W. [Pennsylvania State Univ., University Park, PA (United States). Dept of Physics; Johnson, J. Karl [Univ. of Pittsburgh, PA (United States). Dept. of Chemical and Petroleum Engineering; National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2013-03-01

    Differences in polarizabilities of metallic (M) and semiconducting (S) single-walled carbon nanotubes (SWNTs) might give rise to differences in adsorption potentials. We show from experiments and van der Waals-corrected density functional theory (DFT) that binding energies of Xe adsorbed on M- and S-SWNTs are nearly identical. Temperature programmed desorption of Xe on purified M- and S-SWNTs give similar peak temperatures, indicating that desorption kinetics and binding energies are independent of the type of SWNT. Binding energies computed from vdW-corrected DFT are in good agreement with experiments.

  20. Is there a difference in van der Waals interactions between rare gas atoms adsorbed on metallic and semiconducting single-walled carbon nanotubes?

    Science.gov (United States)

    Chen, De-Li; Mandeltort, Lynn; Saidi, Wissam A; Yates, John T; Cole, Milton W; Johnson, J Karl

    2013-03-29

    The differences in the polarizabilities of metallic (M) and semiconducting (S) single-walled carbon nanotubes (SWNTs) might give rise to differences in adsorption potentials. We show from experiments and van der Waals--corrected density functional theory that the binding energies of Xe adsorbed on M- and S-SWNTs are nearly identical. Temperature programed desorption experiments of Xe on purified M- and S-SWNTs give similar peak temperatures, indicating that desorption kinetics and binding energies are independent of the type of SWNT. Binding energies computed from vdW-corrected density functional theory are in good agreement with experiments.

  1. Lead free CH3NH3SnI3 perovskite thin-film with p-type semiconducting nature and metal-like conductivity

    OpenAIRE

    2016-01-01

    Lead free CH3NH3SnI3 perovskite thin film was prepared by low temperature solution processing and characterized using current sensing atomic force microscopy (CS-AFM). Analysis of electrical, optical, and optoelectrical properties reveals unique p-type semiconducting nature and metal like conductivity of this material. CH3NH3SnI3 film also showed a strong absorption in visible and near infrared spectrum with absorption onset of 1.3 eV. X-ray Diffraction analysis and scanning electron microsco...

  2. Experimental Equipment and Basic Technological Methods of Obtaining Cavitation Protective Coatings on Working Surfaces of Steam Turbine Blades Made of Titanium Alloy VT6 in Order to Replace Imports of Similar Products

    Directory of Open Access Journals (Sweden)

    Bilous, V.A.

    2016-07-01

    Full Text Available The experimental equipment and basic technological methods of obtaining сavitation protective coatings on the working surfaces of blades of steam turbines from titanium alloy VT6 have been created. The selection and the basis of the composition and conditions of synthesis of optimal coating for hardening blades have been justified. The parameters of deposition process of coatings on the blade model have been worked, the experimental technological deposition process of hardening coatings has been created. The tests of titanium alloy VT6 samples with the preferred coatings in simulation conditions close to operational have been conducted. The coatings on the blade model of length up to 130 cm and weight up to 30 kg have been deposited. The velocity of the TiN coating depositing was 10 mkm/h.

  3. Why is Astronomy Important?

    OpenAIRE

    Rosenberg, Marissa; Russo, Pedro; Bladon, Georgia; Christensen, Lars Lindberg

    2013-01-01

    Astronomy and related fields are at the forefront of science and technology; answering fundamental questions and driving innovation. Although blue-skies research like astronomy rarely contributes directly with tangible outcomes on a short time scale, the pursuit of this research requires cutting-edge technology and methods that can on a longer time scale, through their broader application make a difference. A wealth of examples show how the study of astronomy contributes to technology, econom...

  4. Characterization of dilute magnetic semiconducting transition metal doped ZnO thin films by sol–gel spin coating method

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaprasath, G.; Murugan, R. [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Ravi, G., E-mail: gravicrc@gmail.com [Department of Physics, Alagappa University, Karaikudi 630004, Tamil Nadu (India); Mahalingam, T. [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Hayakawa, Y. [Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8011 (Japan)

    2014-09-15

    Graphical abstract: - Highlights: • Diluted magnetic semiconducting TM (Ni, Mn, Co) doped ZnO thin films were fabricated by sol–gel spin coating technique. • The XRD analyses revealed that the TM (Ni, Mn, Co) doped ZnO films have hexagonal wurtzite structure. • Photoluminescence and micro-Raman spectra were interpreted for TM (Ni, Mn, Co) doped ZnO thin films. • SEM morphology studies were made for Zn{sub 0.97} Ni{sub 0.03}O, Zn{sub 0.97} Mn{sub 0.03}O and Zn{sub 0.97} Co{sub 0.03}O thin films. • Room temperature ferromagnetism was observed in TM (Ni, Mn, Co) doped ZnO thin films. - Abstract: Pure and transition metal (TM = Ni, Mn, Co) doped zinc oxide (ZnO) thin films were prepared by sol–gel spin coating method with a concentration of 0.03 mol% of transition metals. X-ray diffraction studies revealed the polycrystalline nature of the films with the presence of hexagonal wurtzite structure. UV transmittance spectra showed that all the films are highly transparent in the visible region and in the case of doped ZnO thin films, d–d transition was observed in the violet region due to the existence of crystalline defects and grain boundaries. The optical band gap of the films decreases with increasing orbital occupation numbers of 3d electrons due to the orbital splitting of magnetic ions. Ultraviolet and near-infrared electronic transitions were observed which reveals a strong relationship with the doping of transition metal into ZnO site. The observed luminescence in the green, violet and red regions strongly depends on the doping elements owing to the different oxygen vacancy, oxygen interstitial, and surface morphology. The surface morphology of thin films was investigated by scanning electron microscope (SEM). The energy dispersive X-ray analysis (EDX) confirmed the stoichiometric composition of the TM doped ZnO thin films. Magnetic measurements at room temperature exhibited well defined ferromagnetic features of the thin films.

  5. Photophysics of quasi-one-dimensional excitons in pi-conjugated polymers and semiconducting single-walled carbon nanotubes

    Science.gov (United States)

    Sheng, Chuanxiang

    In this work we studied the ultrafast dynamics of photoexcitations in pi-conjugated organic semiconductors and semiconducting single-walled carbon nanotubes (S-NTs), using a low-intensity high-repetition rate laser system in the spectral range from 0.13 to 1.05 eV, and high-intensity low-repletion rate laser system in the spectral range from 1.2 to 2.5 eV, in the time domain from 100 fs to 1 ns. We also measured cw photomodulation (PM) spectroscopy of pi-conjugated polymers and photoluminescence (PL) spectra of both polymers and isolated nanotubes. In polymers, we found that excitons are the primary photoexcitations in single polymer chains. However, polarons and polaron pairs may also be photogenerated at early time in films. We consider this process to be extrinsic in nature, namely, dependent on materials properties, temperatures, excitation photon energies, as well as the quality of films. Both annealed and unannealed thin NT films and D2O solutions of isolated NTs were investigated. Various transient photoinduced bleaching (PB) and photoinduced absorption (PA) bands were observed, which also showed photoinduced dichroism and decay together after taking into account the PB spectral shift. The PL emission shows polarization degree. We therefore conclude that the primary photoexcitations in S-NT are excitons that are confined along the NTs. Prom the average PL polarization degree and the transient polarization memory decay, we estimate the PL lifetime in isolated NTs in solution to be of the order of 500 ps, coupling with the minute PL emission quantum efficiency, which indicates weak radiative transition strength. In S-NTs and pi-polymers, the emission spectra relative to the absorption bands are very similar, as well as transient photoinduced absorption bands (PA) with a low-energy PA1 and a higher-energy PA2 in all cases. Theoretical calculations of excited state absorptions within a correlated pi-electron Hamiltonian show the same excitonic energy spectrum

  6. The influence of semiconductive binary Sb{sub 2}S{sub 3}–Yb{sub 3}S{sub 4} system on electrical conductivity property of epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Soydal, Ulku, E-mail: usoydal@selcuk.edu.tr; Ahmetli, Gulnare, E-mail: usoydal@selcuk.edu.tr; Kocaman, Suheyla, E-mail: usoydal@selcuk.edu.tr [Department of Chemical Engineering, Faculty of Engineering, Selcuk University, 42031 Konya (Turkey)

    2014-05-15

    The purpose of this study is to develop the semiconductive composites. Semiconducting glass (SG) binary system Sb{sub 2}S{sub 3}–Yb{sub 3}S{sub 4} in mole ratio 1:1 was synthesized and was doped with I{sub 2}. Next, electrically conductive DGEBA-type epoxy resin (ER)/SG-filled composites and epoxy toluene oligomer (ETO) modified epoxy resin-SG filled composites were developed with 3–10 wt. % of fillers and characterized. As a result, the effects of the modifier and amount of semiconductive filler on the electrical properties of commercial epoxy resin were examined. Percolation concentration was 7 wt. % for all composites. For the SG-reinforced composites, the dispersion of the fillers is investigated by X-ray diffraction (XRD) and by scanning electron microscopy (SEM)

  7. Knowledge Technologies

    CERN Document Server

    Milton, Nick

    2008-01-01

    Several technologies are emerging that provide new ways to capture, store, present and use knowledge. This book is the first to provide a comprehensive introduction to five of the most important of these technologies: Knowledge Engineering, Knowledge Based Engineering, Knowledge Webs, Ontologies and Semantic Webs. For each of these, answers are given to a number of key questions (What is it? How does it operate? How is a system developed? What can it be used for? What tools are available? What are the main issues?). The book is aimed at students, researchers and practitioners interested in Knowledge Management, Artificial Intelligence, Design Engineering and Web Technologies. During the 1990s, Nick worked at the University of Nottingham on the application of AI techniques to knowledge management and on various knowledge acquisition projects to develop expert systems for military applications. In 1999, he joined Epistemics where he worked on numerous knowledge projects and helped establish knowledge management...

  8. Seafood Technology

    DEFF Research Database (Denmark)

    Børresen, Torger

    This presentation will fill the total picture of this conference between fisheries and aquaculture, blue biotech and bioconservation, by considering the optimal processing technology of marine resources from the raw material until the seafood reaches the plate of the consumer. The situation today...... must be performed such that total traceability and authenticity of the final products can be presented on demand. The most important aspects to be considered within seafood technology today are safety, healthy products and high eating quality. Safety can be divided into microbiological safety...... and not presenting any safety risk per se. Seafood is healthy due to the omega-3 fatty acids and the nutritional value of vitamins, peptides and proteins. The processing technology must however be performed such that these valuable features are not lost during production. The same applies to the eating quality. Any...

  9. Fiscal 1997 R and D project on industrial science and technology under a consignment from NEDO. R and D of the superconducting material and device (technical development of the Josephson device hybrid system); 1997 nendo sangyo kagaku gijutsu kenkyu kaihatsu jigyo Shin energy Sangyo Gijutsu Sogo Kaihatsu Kiko itaku. Chodendo zairyo chodendo soshi no kenkyu kaihatsu (Josephson soshi hybrid system no gijutsu kaihatsu) seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    In order to establish basic technology for hybrid systems of superconducting and semiconducting devices, study was made on ultrahigh speed and low energy consumption properties of Josephson devices. As Josephson IC technology, a logical circuit, ring network, memory circuit, and oxide superconductor logical circuit were studied. As superconducting hybrid system technology, a Josephson device- semiconductor device interface, formation technology of signal transmission lines, and Josephson-MOS IC technology were developed. In fiscal 1997, as Josephson IC technology, switch motion of 4GHz in clock frequency was achieved by new high-density wiring process. Integration of some semiconducting processor elements, junction of surface- stabilized superconducting thin films, and motion of combination structure of some SQUIDs were also confirmed. On the hybrid system, voltage conversion operation of all interfaces was confirmed. Proper logical operation of the Josephson device hybrid circuit was also confirmed. 95 refs., 90 figs., 5 tabs.

  10. Photofragmentation of the closo-carboranes part II: VUV assisted dehydrogenation in the closo-carboranes and semiconducting B10C2H(x) films.

    Science.gov (United States)

    Rühl, Eckart; Riehs, Norman F; Behera, Swayambhu; Wilks, Justin; Liu, Jing; Jochims, H-W; Caruso, Anthony N; Boag, Neil M; Kelber, Jeffry A; Dowben, Peter A

    2010-07-15

    The dehydrogenation of semiconducting boron carbide (B(10)C(2)H(x)) films as well as the three closo-carborane isomers of dicarbadodecaborane (C(2)B(10)H(12)) and two isomers of the corresponding closo-phosphacarborane (PCB(10)H(11)) all appear to be very similar. Photoionization mass spectrometry studies at near-threshold gas phase photoionization indicate that the preferred pathway for dissociation of the parent cation species (C(2)B(10)H(10)(+) or PCB(10)H(9)(+)) is, in all cases, the loss of H(2). Ab initio density functional theory (DFT) calculations indicate that energetically preferred sites for exopolyhedral hydrogen (B-H) bond dissociation are in all cases at B atoms opposite the C atoms in the parent cage molecule. The site of photodissociation of hydrogen from semiconducting boron carbide (B(10)C(2)H(x)) films, fabricated by plasma-enhanced chemical vapor deposition, is a cage boron atom that can bond to nitrogen upon exposure to VUV light in the presence of NH(3). Shifts in core level binding energies due to nitrogen bond formation indicate that B-N bond formation occurs only at B atoms bound to other boron atoms (B-B sites) and not at B-C sites or at C sites, in agreement with gas phase results.

  11. Bionano donor-acceptor hybrids of porphyrin, ssDNA, and semiconductive single-wall carbon nanotubes for electron transfer via porphyrin excitation.

    Science.gov (United States)

    D'Souza, Francis; Das, Sushanta K; Zandler, Melvin E; Sandanayaka, Atula S D; Ito, Osamu

    2011-12-14

    Photoinduced electron transfer in self-assemblies of porphyrins ion-paired with ssDNA wrapped around single-wall carbon nanotubes (SWCNTs) has been reported. To accomplish the three-component hybrids, two kinds of diameter-sorted semiconducting SWCNT(n,m)s of different diameter ((n,m) = (6,5) and (7,6)) and free-base or zinc porphyrin bearing peripheral positive charges ((TMPyP(+))M (tetrakis(4-N-methylpyridyl)porphyrin); M = Zn and H(2)) serving as light-absorbing photoactive materials are utilized. The donor-acceptor hybrids are held by ion-pairing between the negatively charged phosphate groups of ssDNA on the surface of the SWCNT and the positively charged at the ring periphery porphyrin macrocycle. The newly assembled bionano donor-acceptor hybrids have been characterized by transmission electron microscopy (TEM) and spectroscopic methods. Photoinduced electron transfer from the excited singlet porphyrin to the SWCNTs directly and/or via ssDNA as an electron mediator has been established by performing systematic studies involving the steady-state and time-resolved emission as well as the transient absorption studies. Higher charge-separation efficiency has been successfully demonstrated by the selection of the appropriate semiconductive SWCNTs with the right band gap, in addition to the aid of ssDNA as the electron mediator. © 2011 American Chemical Society

  12. Growth of Horizontal Semiconducting SWNT Arrays with Density Higher than 100 tubes/μm using Ethanol/Methane Chemical Vapor Deposition.

    Science.gov (United States)

    Kang, Lixing; Zhang, Shuchen; Li, Qingwen; Zhang, Jin

    2016-06-01

    Horizontally aligned semiconducting single-walled carbon nanotube (s-SWNT) arrays with a certain density are highly desirable for future electronic devices. However, obtaining s-SWNT arrays with simultaneously high purity and high density is extremely challenging. We report herein a rational approach, using ethanol/methane chemical vapor deposition, to grow SWNT arrays with a s-SWNT ratio over 91% and a density higher than 100 tubes/μm. In this approach, at a certain temperature, ethanol was fully thermally decomposed to feed carbon atoms for Trojan-Mo catalysts growing high density SWNT arrays, while the incomplete pyrolysis of methane provided appropriate active H radicals with the help of catalytic sapphire surface to inhibit metallic SWNT (m-SWNT) growth. The synergistic effect of ethanol/methane mixtures resulted in enriched semiconducting SWNTs and no obvious decrease in nanotube density due to their milder reactivity and higher controllability at suitable growth conditions. This work represents a step forward in large-area synthesis of high density s-SWNT arrays on substrates and demonstrates potential applications in scalable carbon nanotube electronics.

  13. Nanoengineering Ni(x)Fe(1-x) catalysts for gas-phase, selective synthesis of semiconducting single-walled carbon nanotubes.

    Science.gov (United States)

    Chiang, Wei-Hung; Sakr, Mohammed; Gao, Xuan P A; Sankaran, R Mohan

    2009-12-22

    The inhomogeneity of as-grown single-walled carbon nanotubes (SWCNTs), in terms of chiral structure, is a major obstacle to integration of these novel materials in advanced electronics. While separation methods have circumvented this problem, current synthesis approaches must be refined for large-scale production of SWCNTs with uniform properties. In addition, it is highly desirable to alter the initial chirality distribution which constrains fundamental study and applications. Here, we demonstrate that semiconducting SWCNTs are selectively produced in the gas phase by engineering catalysts at the nanoscale with precise size and composition. The semiconducting content in as-grown mixtures of SWCNTs is assessed by UV-visible-NIR absorbance and micro-Raman spectroscopy and reaches a maximum purity of 90% for samples catalyzed by Ni(0.27)Fe(0.73) nanoparticles (2.0 nm mean diameter). Electrical studies are performed on thin film transistors (TFTs) fabricated from as-grown SWCNTs and reveal high on/off current ratios of 10(3).

  14. Surface properties of annealed semiconducting β-Ga{sub 2}O{sub 3} (1 0 0) single crystals for epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Navarro-Quezada, A., E-mail: andrea.navarro-quezada@jku.at [Leibniz Institut für Analytische Wissenschaften ISAS – e.V., Schwarzschildstr. 8, 12489 Berlin (Germany); Galazka, Z. [Leibniz Institut für Kristallzüchtung, Max-Born-Str. 2, 12489 Berlin (Germany); Alamé, S. [Leibniz Institut für Analytische Wissenschaften ISAS – e.V., Schwarzschildstr. 8, 12489 Berlin (Germany); Technische Universität Berlin, Institute of Solid State Physics, Hardenbergstr. 36, 10623 Berlin (Germany); Skuridina, D.; Vogt, P. [Technische Universität Berlin, Institute of Solid State Physics, Hardenbergstr. 36, 10623 Berlin (Germany); Esser, N. [Leibniz Institut für Analytische Wissenschaften ISAS – e.V., Schwarzschildstr. 8, 12489 Berlin (Germany)

    2015-09-15

    Highlights: • Epiready substrate surfaces of semiconducting β-Ga{sub 2}O{sub 3} are annealed and analyzed by photoelectron emission spectroscopy. • The surface carbon contamination is monitored as a function of annealing temperature up to 800 °C in ultra-high vacuum • Carbon can be eliminated up to 70% by annealing to 800 °C. • An increment in the surface valence band bending with annealing is observed associated to defects. - Abstract: We present a detailed study on the surface properties of conductive β-Ga{sub 2}O{sub 3} (1 0 0) single-crystal epiready substrates by means of photoelectron emission spectroscopy. The surface properties are studied prior and after annealing in ultra-high vacuum (UHV). We find that untreated substrates contain a significant amount of adsorbed carbon contaminations at the surface, which can be partly removed by annealing at 800 °C in UHV. Valence band photoemission evidences an upward band bending of about 0.5 eV that increases with annealing, revealing the presence of an electron depletion layer at the near-surface region responsible for the insulating behavior commonly observed for semiconductive β-Ga{sub 2}O{sub 3} single crystals. Our findings become crucial for epitaxial growth, as it is known that carbon modifies the electrical and structural properties of subsequent epitaxial layers.

  15. he Importance of the use of the Information and Communication Technologies(ICT) in the Small and Medium-size Enterprises(SMEs) of trade, industry and services in Colima and Villa de Alvarez

    OpenAIRE

    2008-01-01

    The ICT revolution has increased the use of technology because of knowledge intensive economy that aims to improve efficiency and productivity levels in the enterprises due to ICT. This is the reason to quantify the adoption degree of ICT used by the small and medium enterprises (SME) in Colima and Villa de Alvarez. The aggregation level hides the diversity in the behavior patterns of the SME, as a result the SME in commerce and services have similar patterns in the adoption of ICT, wh...

  16. FY 1993 report of the results of the R and D of the important regional technology - Laser application advanced processing system technology. II. R and D of the composite functional member structure control technology (Development of the high grade surface processing technology of methane fueled aircraft use engine members); 1993 nendo juyo chiiki gijutsu kenkyu kaihtsu (fukugo kino buzai kozo seigyo gijutsu no kenkyu kaihatsu (methane nenryo kokukiyo engine buzai no kodo hyomen kako gijutsu kaihatsu). 2. Laser oyo senshin kako system gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-03-01

    In the fields of aerospace, energy, etc., the development is expected of materials for engine members which are reliable and durable for a long time under the severe environment. Materials are developed which are erosion-resistant under the non-erosion environment of the front of engine of methane fueled aircraft. The basic experiment was commenced on the fabrication of micro-fine surface of Ti-6Al-4V alloys, etc. by superimposed laser beam irradiation. As a technology to fabricate the composite surface layer by supplying alloy components on the material surface, the development was started of a technology to form hard coating by irradiating laser to the Ti alloy surface put with metal elements and compounds on. Literature survey was made of the laser surface reforming technology of Ti alloys, etc. using JOIS. As to the fabrication of the composite surface layer, it was found out that the layer is easy to be brittle together with hardness. In the experiment on the micro-fine surface fabrication, it was found out that as a characteristic of light collector, the integration mirror is flat in strength distribution. Concerning the fabrication of the composite surface layer, it is a must to make it gradient because micro cracks are generated with the rising surface hardness. (NEDO)

  17. Developing a scalable artificial photosynthesis technology through nanomaterials by design

    Science.gov (United States)

    Lewis, Nathan S.

    2016-12-01

    An artificial photosynthetic system that directly produces fuels from sunlight could provide an approach to scalable energy storage and a technology for the carbon-neutral production of high-energy-density transportation fuels. A variety of designs are currently being explored to create a viable artificial photosynthetic system, and the most technologically advanced systems are based on semiconducting photoelectrodes. Here, I discuss the development of an approach that is based on an architecture, first conceived around a decade ago, that combines arrays of semiconducting microwires with flexible polymeric membranes. I highlight the key steps that have been taken towards delivering a fully functional solar fuels generator, which have exploited advances in nanotechnology at all hierarchical levels of device construction, and include the discovery of earth-abundant electrocatalysts for fuel formation and materials for the stabilization of light absorbers. Finally, I consider the remaining scientific and engineering challenges facing the fulfilment of an artificial photosynthetic system that is simultaneously safe, robust, efficient and scalable.

  18. Developing a scalable artificial photosynthesis technology through nanomaterials by design.

    Science.gov (United States)

    Lewis, Nathan S

    2016-12-06

    An artificial photosynthetic system that directly produces fuels from sunlight could provide an approach to scalable energy storage and a technology for the carbon-neutral production of high-energy-density transportation fuels. A variety of designs are currently being explored to create a viable artificial photosynthetic system, and the most technologically advanced systems are based on semiconducting photoelectrodes. Here, I discuss the development of an approach that is based on an architecture, first conceived around a decade ago, that combines arrays of semiconducting microwires with flexible polymeric membranes. I highlight the key steps that have been taken towards delivering a fully functional solar fuels generator, which have exploited advances in nanotechnology at all hierarchical levels of device construction, and include the discovery of earth-abundant electrocatalysts for fuel formation and materials for the stabilization of light absorbers. Finally, I consider the remaining scientific and engineering challenges facing the fulfilment of an artificial photosynthetic system that is simultaneously safe, robust, efficient and scalable.

  19. Conducting a Technology Audit

    Science.gov (United States)

    Flaherty, William

    2011-01-01

    Technology is a critical component in the success of any high-functioning school district, thus it is important that education leaders should examine it closely. Simply put, the purpose of a technology audit is to assess the effectiveness of the technology for administrative or instructional use. Rogers Public Schools in Rogers, Arkansas, recently…

  20. Technological Style is History

    DEFF Research Database (Denmark)

    Blond, Lasse

    The effort to comprehend innovation across cultures and time highlights the importance of the explicating factors external to technology. It becomes relevant to nuance or differentiate the understanding of social and cultural responses to adopted technologies by recognizing that technology shapes...