WorldWideScience

Sample records for room temperature realized

  1. Toward realizing high power semiconductor terahertz laser sources at room temperature

    Science.gov (United States)

    Razeghi, Manijeh

    2011-05-01

    The terahertz (THz) spectral range offers promising applications in science, industry, and military. THz penetration through nonconductors (fabrics, wood, plastic) enables a more efficient way of performing security checks (for example at airports), as illegal drugs and explosives could be detected. Being a non-ionizing radiation, THz radiation is environment-friendly enabling a safer analysis environment than conventional X-ray based techniques. However, the lack of a compact room temperature THz laser source greatly hinders mass deployment of THz systems in security check points and medical centers. In the past decade, tremendous development has been made in GaAs/AlGaAs based THz Quantum Cascade Laser (QCLs), with maximum operating temperatures close to 200 K (without magnetic field). However, higher temperature operation is severely limited by a small LO-phonon energy (~ 36 meV) in this material system. With a much larger LO-phonon energy of ~ 90 meV, III-Nitrides are promising candidates for room temperature THz lasers. However, realizing high quality material for GaN-based intersubband devices presents a significant challenge. Advances with this approach will be presented. Alternatively, recent demonstration of InP based mid-infrared QCLs with extremely high peak power of 120 W at room temperature opens up the possibility of producing high power THz emission with difference frequency generation through two mid-infrared wavelengths.

  2. High-responsivity, low-noise, room-temperature, self-mixing terahertz detector realized using floating antennas on a GaN-based field-effect transistor

    Science.gov (United States)

    Sun, J. D.; Sun, Y. F.; Wu, D. M.; Cai, Y.; Qin, H.; Zhang, B. S.

    2012-01-01

    Using only optical lithography, we have fabricated a GaN/AlGaN high-electron mobility transistor with distinctive source and drain antennas electrically isolated from the electron channel. Working at room temperature, it efficiently detects terahertz radiation via self-mixing, with a responsivity (3.6 kV/W) exceptionally high for a III-V device and with a noise (40pW/√Hz ) just above the thermal limit. Performance improves at 77 K. While the device itself is micrometer-sized, our modeling indicates the asymmetric antennas induce a rather localized (<200 nm) region of strong self-mixing. Thus, a nanometer-scale active region is achieved by design and without recourse to electron-beam lithography.

  3. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Amita

    2004-11-01

    distribution of Mn substituting for Zn a 2+ state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2+ state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

  4. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Amita [KTH Royal Inst. of Technology, Stockholm (Sweden)

    2004-06-01

    distribution of Mn substituting for Zn a 2+ state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2+ state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

  5. ITO films realized at room-temperature by ion beam sputtering for high-performance flexible organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, B.; Rammal, W.; Moliton, A. [Limoges Univ., Faculte des Sciences et Techniques, CNRS, UMR 6172, Institut de Recherche XLIM, Dept. MINACOM, 87 - Limoges (France)

    2006-06-15

    Indium-tin oxide (ITO) thin layers are obtained by an IBS (Ion Beam Sputtering) deposition process. We elaborated ITO films on flexible substrates of polyethylene terephthalate (PET), under soft conditions of low temperatures and fulfilling the requirements of fabrication processes of the organic optoelectronic components. With a non thermally activated (20 Celsius degrees) ITO deposition assisted by an oxygen flow (1 cm{sup 3}/min), we got an optical transmittance of 90% in the visible range, a resistivity around 10{sup -3} {omega}.cm and a surface roughness lower than 1.5 mm. Thus we realized flexible organic light-emitting diodes (FOLEDs) with good performances: a maximum luminance of 12000 cd/m{sup 2} at a voltage of 19 V and a maximum luminous power efficiency around 1 lm/W at a voltage of 10 V (or a maximum current efficiency of 4 cd/A at 14 V) for the (PET(50 {mu}m) / ITO(200 nm) / TPD(40 nm) / Alq3(60 nm) / Ca / Al) structure. (authors)

  6. Modelling room temperature ionic liquids.

    Science.gov (United States)

    Bhargava, B L; Balasubramanian, Sundaram; Klein, Michael L

    2008-08-07

    Room temperature ionic liquids (IL) composed of organic cations and inorganic anions are already being utilized for wide-ranging applications in chemistry. Complementary to experiments, computational modelling has provided reliable details into the nature of their interactions. The intra- and intermolecular structures, dynamic and transport behaviour and morphologies of these novel liquids have also been explored using simulations. The current status of molecular modelling studies is presented along with the prognosis for future work in this area.

  7. Polariton condensates at room temperature

    Science.gov (United States)

    Guillet, Thierry; Brimont, Christelle

    2016-10-01

    We review the recent developments of the polariton physics in microcavities featuring the exciton-photon strong coupling at room temperature, and leading to the achievement of room-temperature polariton condensates. Such cavities embed active layers with robust excitons that present a large binding energy and a large oscillator strength, i.e. wide bandgap inorganic or organic semiconductors, or organic molecules. These various systems are compared, in terms of figures of merit and of common features related to their strong oscillator strength. The various demonstrations of polariton laser are compared, as well as their condensation phase diagrams. The room-temperature operation indeed allows a detailed investigation of the thermodynamic and out-of-equilibrium regimes of the condensation process. The crucial role of the spatial dynamics of the condensate formation is discussed, as well as the debated issue of the mechanism of stimulated relaxation from the reservoir to the condensate under non-resonant excitation. Finally the prospects of polariton devices are presented.

  8. Room temperature stable single-photon source

    CERN Document Server

    Beveratos, A; Brouri, R; Gacoin, T; Poizat, J P; Grangier, P; Beveratos, Alexios; Kuehn, Sergei; Brouri, Rosa; Gacoin, Thierry; Poizat, Jean-Philippe; Grangier, Philippe

    2001-01-01

    We report on the realization of a stable solid state room temperature source for single photons. It is based on the fluorescence of a single nitrogen-vacancy (NV) color center in a diamond nanocrystal. Antibunching has been observed in the fluorescence light under both continuous and pulsed excitation. Our source delivers 2*10^4 single-photon pulses per second at an excitation repetition rate of 10 MHz. The number of two-photon pulses is reduced by a factor of five compared to strongly attenuated coherent sources.

  9. Thermal expansion of ceramics around room temperature

    OpenAIRE

    橋本, 忍; 安達, 信泰; 太田, 敏孝; 宮崎, 英敏; ハシモト, シノブ; アダチ, ノブヤス; オオタ, トシタカ; Hashimoto, Shinobu; Adachi, Nobuyasu; Ota, Toshitaka

    2010-01-01

    Thermal expansion of some ceramics, polymers and metals was measured by dilatometer around room temperature (from -140℃to +200℃), and compared with thermal expansion in the high temperature region. The CTE (coefficient of thermal expansion)of almost ceramics changed drastically between room temperature and high temperature region. On the other hand, the CTE ofmetals did not change between room temperature and high temperature region. The difference on thermal expansion betweenceramics and met...

  10. Room-temperature solid-state maser.

    Science.gov (United States)

    Oxborrow, Mark; Breeze, Jonathan D; Alford, Neil M

    2012-08-16

    The invention of the laser has resulted in many innovations, and the device has become ubiquitous. However, the maser, which amplifies microwave radiation rather than visible light, has not had as large an impact, despite being instrumental in the laser's birth. The maser's relative obscurity has mainly been due to the inconvenience of the operating conditions needed for its various realizations: atomic and free-electron masers require vacuum chambers and pumping; and solid-state masers, although they excel as low-noise amplifiers and are occasionally incorporated in ultrastable oscillators, typically require cryogenic refrigeration. Most realizations of masers also require strong magnets, magnetic shielding or both. Overcoming these various obstacles would pave the way for improvements such as more-sensitive chemical assays, more-precise determinations of biomolecular structure and function, and more-accurate medical diagnostics (including tomography) based on enhanced magnetic resonance spectrometers incorporating maser amplifiers and oscillators. Here we report the experimental demonstration of a solid-state maser operating at room temperature in pulsed mode. It works on a laboratory bench, in air, in the terrestrial magnetic field and amplifies at around 1.45 gigahertz. In contrast to the cryogenic ruby maser, in our maser the gain medium is an organic mixed molecular crystal, p-terphenyl doped with pentacene, the latter being photo-excited by yellow light. The maser's pumping mechanism exploits spin-selective molecular intersystem crossing into pentacene's triplet ground state. When configured as an oscillator, the solid-state maser's measured output power of around -10 decibel milliwatts is approximately 100 million times greater than that of an atomic hydrogen maser, which oscillates at a similar frequency (about 1.42 gigahertz). By exploiting the high levels of spin polarization readily generated by intersystem crossing in photo-excited pentacene and other

  11. Realization of band gap shrinkage to the spectral characteristics of high-luminous-efficiency 658 nm AlGaInP/GaInP multiple quantum well lasers at room temperatures

    Science.gov (United States)

    Chackrabarti, Santosh; Zargar, Rayees A.; Bansal, Jyoti; Zaker, Tho-alfiqar A.; Hafiz, A. K.

    2016-08-01

    The temperature dependent spectral shifts in 658 nm AlGaInP multiple quantum well (MQW) red laser diodes due to band gap narrowing at room temperatures (5 °Csbnd 45 °C) is reported. The density of states effective mass approximation and the conduction band effective mass approximation are employed to formulate the carrier concentrations. The spectral shift mechanism is explored with a threshold current density of 42.28 kA/cm2 and a good characteristic temperature of 149 K. The photoluminescence (PL) peak intensity shifts towards the higher wavelength(red shift) and the full width at half maximum (FWHM) increases with the increase in temperature. The band gap narrowing value determined by a simple formula amounts to 67.4 meV and displays N1/3 dependence at higher densities. The carrier density dependence conveys that the red shift of the spectral emission is due to band gap narrowing.

  12. Topological Insulators at Room Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haijun; /Beijing, Inst. Phys.; Liu, Chao-Xing; /Tsinghua U., Beijing; Qi, Xiao-Liang; /Stanford U., Phys. Dept.; Dai, Xi; Fang, Zhong; /Beijing, Inst. Phys.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-25

    Topological insulators are new states of quantum matter with surface states protected by the time-reversal symmetry. In this work, we perform first-principle electronic structure calculations for Sb{sub 2}Te{sub 3}, Sb{sub 2}Se{sub 3}, Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} crystals. Our calculations predict that Sb{sub 2}Te{sub 3}, Bi{sub 2}T e{sub 3} and Bi{sub 2}Se{sub 3} are topological insulators, while Sb{sub 2}Se{sub 3} is not. In particular, Bi{sub 2}Se{sub 3} has a topologically non-trivial energy gap of 0.3eV , suitable for room temperature applications. We present a simple and unified continuum model which captures the salient topological features of this class of materials. These topological insulators have robust surface states consisting of a single Dirac cone at the {Lambda} point.

  13. Room temperature creep in metals and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Deibler, Lisa Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Characterization and Performance

    2014-09-01

    Time dependent deformation in the form of creep and stress relaxation is not often considered a factor when designing structural alloy parts for use at room temperature. However, creep and stress relaxation do occur at room temperature (0.09-0.21 Tm for alloys in this report) in structural alloys. This report will summarize the available literature on room temperature creep, present creep data collected on various structural alloys, and finally compare the acquired data to equations used in the literature to model creep behavior. Based on evidence from the literature and fitting of various equations, the mechanism which causes room temperature creep is found to include dislocation generation as well as exhaustion.

  14. Room temperature ferromagnetism in Teflon due to carbon dangling bonds.

    Science.gov (United States)

    Ma, Y W; Lu, Y H; Yi, J B; Feng, Y P; Herng, T S; Liu, X; Gao, D Q; Xue, D S; Xue, J M; Ouyang, J Y; Ding, J

    2012-03-06

    The ferromagnetism in many carbon nanostructures is attributed to carbon dangling bonds or vacancies. This provides opportunities to develop new functional materials, such as molecular and polymeric ferromagnets and organic spintronic materials, without magnetic elements (for example, 3d and 4f metals). Here we report the observation of room temperature ferromagnetism in Teflon tape (polytetrafluoroethylene) subjected to simple mechanical stretching, cutting or heating. First-principles calculations indicate that the room temperature ferromagnetism originates from carbon dangling bonds and strong ferromagnetic coupling between them. Room temperature ferromagnetism has also been successfully realized in another polymer, polyethylene, through cutting and stretching. Our findings suggest that ferromagnetism due to networks of carbon dangling bonds can arise in polymers and carbon-based molecular materials.

  15. Room-temperature antiferromagnetic memory resistor.

    Science.gov (United States)

    Marti, X; Fina, I; Frontera, C; Liu, Jian; Wadley, P; He, Q; Paull, R J; Clarkson, J D; Kudrnovský, J; Turek, I; Kuneš, J; Yi, D; Chu, J-H; Nelson, C T; You, L; Arenholz, E; Salahuddin, S; Fontcuberta, J; Jungwirth, T; Ramesh, R

    2014-04-01

    The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.

  16. Electrically Injected Twin Photon Emitting Lasers at Room Temperature

    Directory of Open Access Journals (Sweden)

    Claire Autebert

    2016-08-01

    Full Text Available On-chip generation, manipulation and detection of nonclassical states of light are some of the major issues for quantum information technologies. In this context, the maturity and versatility of semiconductor platforms are important assets towards the realization of ultra-compact devices. In this paper we present our work on the design and study of an electrically injected AlGaAs photon pair source working at room temperature. The device is characterized through its performances as a function of temperature and injected current. Finally we discuss the impact of the device’s properties on the generated quantum state. These results are very promising for the demonstration of electrically injected entangled photon sources at room temperature and let us envision the use of III-V semiconductors for a widespread diffusion of quantum communication technologies.

  17. Controllability of room air temperature. Huonelaempoetilan saeaetoe

    Energy Technology Data Exchange (ETDEWEB)

    Laitila, P.; Katajisto, K.; Karjalainen, S.; Lassila, K. (Valtion Teknillinen Tutkimuskeskus, Espoo (Finland). LVI-tekniikan Laboratorio)

    1991-01-15

    At first, the control loop of room air temperature was studied as a unit process to find out the characteristic controllability factors of the process as well as possible. Step-response tests were made to the process. Furthermore, the choice of the control law, the adjustment of the controller parameters and the applicability of the controller parameters were analyzed. The results are based mainly on the simulation studies of the office building using the TRNSYS, HVACSIM{sup +} and PIPNET simulation programs. When making a step-change, e.g. to inlet air temperature, it takes a long time before the room air temperature achieves its final steady state. In addition, the gain of the process is slow. The time constant of the process is 30 min - 100 min. The steady state in terms of controllability is achieved in approximately four hours. The control difficulty of the process is significant below 0,1 independently of a heating or air conditioning system of the room space. The centralized and the distributed control of the room air temperature was studied as well. When the loads in different spaces differed greatly from one another, temperature conditions could not be controlled using centralized control. In that case the distributed temperature control based on room or zone space should be used. The integrated control of the air conditioning and heating systems proved to be quite difficult on the basis of the simulation studies especially when external loads vary a lot. The measurements made in a building in prevailing conditions did not support the integrated control of the air conditioning and heating systems. However, the heating system was under-dimensioned compared to the air conditioning system.

  18. Materials for room temperature magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Rosendahl Hansen, B.

    2010-07-15

    Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material to change its temperature when a magnetic field is applied or removed. For room temperature cooling, one utilizes that the magnetocaloric effect peaks near magnetic phase transitions and so the materials of interest all have a critical temperature within the range of 250 - 310 K. A magnetic refrigerant should fulfill a number of criteria, among these a large magnetic entropy change, a large adiabatic temperature change, preferably little to no thermal or magnetic hysteresis and the material should have the stability required for long term use. As the temperature range required for room temperature cooling is some 40 - 50 K, the magnetic refrigerant should also be able to cover this temperature span either by exhibiting a very broad peak in magnetocaloric effect or by providing the opportunity for creating a materials series with varying transition temperatures. (Author)

  19. Room Temperature Ferromagnetic Mn:Ge(001

    Directory of Open Access Journals (Sweden)

    George Adrian Lungu

    2013-12-01

    Full Text Available We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001, heated at relatively high temperature (starting with 250 °C. The samples were characterized by low energy electron diffraction (LEED, scanning tunneling microscopy (STM, high resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, superconducting quantum interference device (SQUID, and magneto-optical Kerr effect (MOKE. Samples deposited at relatively elevated temperature (350 °C exhibited the formation of ~5–8 nm diameter Mn5Ge3 and Mn11Ge8 agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe~2.5 phase, or manganese diluted into the Ge(001 crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001. The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed.

  20. Physical understanding of negative bias temperature instability below room temperature

    Science.gov (United States)

    Ji, Xiaoli; Liao, Yiming; Yan, Feng; Zhu, Chenxin; Shi, Yi; Guo, Qiang

    2012-11-01

    The physical mechanism of VT degradations under negative bias temperature stress below room temperature has been studied for SiO2 and plasma nitrided oxide (PNO-based) pMOSFETs. It is found that VT degradations in both devices exhibit strong dependence on the electric field and temperature. The analysis shows that this strong dependence follows multi-phonon field-assisted tunneling theory, which indicates the inelastic hole trapping mechanism in the low temperature negative bias temperature instability (NBTI). On the other hand, by applying a low temperature sweeping technique, the energy distribution of these NBTI-induced hole traps below room temperature is indentified. The energy distribution of hole traps has two obvious peaks, one in the lower and one in the upper half of the silicon band gap. Both peaks gradually develop with increasing the stress time and temperature. We attempt to compare the energy profile for SiO2 and PNO devices to identify the trap precursors in NBTI below room temperature.

  1. Materials for Room Temperature Magnetic Refrigeration

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl

    Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered...... candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material...... to change its temperature when a magnetic field is applied or removed. For room temperature cooling, one utilizes that the magnetocaloric effect peaks near magnetic phase transitions and so the materials of interest all have a critical temperature within the range of 250 – 310 K. A magnetic refrigerant...

  2. Analysis of room temperature magnetic regenerative refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Shir, F.; Mavriplis, C.; Bennett, L.H.; Torre, E.D. [George Washington University, Washington, DC (United States). Institute for Magnetics Research

    2005-06-01

    Results of a room temperature magnetic refrigeration test bed and an analysis using a computational model are presented. A detailed demonstration of the four sequential processes in the transient magnetocaloric regeneration process of a magnetic material is presented. The temperature profile during the transient approach to steady state operation was measured in detail. A 5 {sup o}C evolution of the difference of temperature between the hot end and the cold end of the magnetocaloric bed due to regeneration is reported. A model is developed for the heat transfer and fluid mechanics of the four sequential processes in each cycle of thermal wave propagation in the regenerative bed combined with the magnetocaloric effect. The basic equations that can be used in simulation of magnetic refrigeration systems are derived and the design parameters are discussed. (author)

  3. Nanoscale structural modulation and enhanced room-temperature multiferroic properties.

    Science.gov (United States)

    Sun, Shujie; Huang, Yan; Wang, Guopeng; Wang, Jianlin; Fu, Zhengping; Peng, Ranran; Knize, Randy J; Lu, Yalin

    2014-11-21

    Availability of a single-phase multiferroic material functional at room temperature poses a big challenge, although it is very important to both fundamental physics and application development. Recently, layered Aurivillius oxide materials, one of the most promising candidates, have attracted considerable interest. In this work, we investigated the nanoscale structural evolution of the six-layer Bi7Fe(3-x)Co(x)Ti3O21 when substituting excessive Co. Nanoscale structural modulation (NSM) occurred at the boundaries when changing the material gradually from the originally designed six-layer nanoscale architecture down to five and then four, when increasing the Co content, inducing a previously unidentified analogous morphotropic transformation (AMT) effect. The AMT's net contribution to the enhanced intrinsic multiferroic properties at room temperature was confirmed by quantifying and deducting the contribution from the existing impurity phase using derivative thermo-magneto-gravimetry measurements (DTMG). Significantly, this new AMT effect may be caused by a possible coupling contribution from co-existing NSM phases, indicating a potential method for realizing multiferroic materials that function at room temperature.

  4. A room temperature light source based on silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lo Faro, M.J. [CNR-IPCF, Istituto per i Processi Chimico-Fisici, V. le F. Stagno D' Alcontres 37, 98158 Messina (Italy); MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via Santa Sofia 64, 95123 Catania (Italy); D' Andrea, C. [MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Messina, E.; Fazio, B. [CNR-IPCF, Istituto per i Processi Chimico-Fisici, V. le F. Stagno D' Alcontres 37, 98158 Messina (Italy); Musumeci, P. [Dipartimento di Fisica e Astronomia, Università di Catania, Via Santa Sofia 64, 95123 Catania (Italy); Franzò, G. [MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Gucciardi, P.G.; Vasi, C. [CNR-IPCF, Istituto per i Processi Chimico-Fisici, V. le F. Stagno D' Alcontres 37, 98158 Messina (Italy); Priolo, F. [MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Via Santa Sofia 64, 95123 Catania (Italy); Scuola Superiore di Catania, Via Valdisavoia 9, 95123 Catania (Italy); Iacona, F. [MATIS CNR-IMM, Istituto per la Microelettronica e Microsistemi, Via Santa Sofia 64, 95123 Catania (Italy); Irrera, A., E-mail: irrera@me.cnr.it [CNR-IPCF, Istituto per i Processi Chimico-Fisici, V. le F. Stagno D' Alcontres 37, 98158 Messina (Italy)

    2016-08-31

    We synthesized ultrathin Si nanowires (NWs) by metal assisted chemical wet etching, using a very thin discontinuous Au layer as precursor for the process. A bright room temperature emission in the visible range due to electron–hole recombination in quantum confined Si NWs is reported. A single walled carbon nanotube (CNT) suspension was prepared and dispersed in Si NW samples. The hybrid Si NW/CNT system exhibits a double emission at room temperature, both in the visible (due to Si NWs) and the IR (due to CNTs) range, thus demonstrating the realization of a low-cost material with promising perspectives for applications in Si-based photonics. - Highlights: • Synthesis of ultrathin Si nanowires (NWs) by metal-assisted chemical etching • Synthesis of NW/carbon nanotube (CNT) hybrid systems • Structural characterization of Si NWs and Si NW/CNT • Room temperature photoluminescence (PL) properties of Si NWs and of Si NW/CNT • Tuning of the PL properties of the Si NW/CNT hybrid system.

  5. Absorber Materials at Room and Cryogenic Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun

    2011-09-01

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  6. Fluorescence of fullerene derivatives at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lin, S.K.; Shiu, L.L.; Chien, K.M.; Luh, T.Y.; Lin, T.I. (National Taiwan Univ., Taipei (Taiwan, Province of China))

    1995-01-05

    The absorption and fluorescence spectral properties of fullerene (C[sub 60]) and its derivatives C[sub 60]C[sub 4]H[sub 6], C[sub 60]C[sub 5]H[sub 6], C[sub 60]CHCO[sub 2]Et, and C[sub 60]NCO[sub 2]Et at room temperature were investigated. Breaking the structural symmetry of C[sub 60] results in enhancing the fluorescence quantum yield 2-3-fold in some derivatives. Thus, the room temperature fluorescence of fullerene compounds could be detected more rapidly. New absorption bands and altered fluorescence spectra were observed in the derivatives. The Stokes' shifts of the derivatives are small, about 4-5 nm, compared to 68 nm for the parent compound. The time-resolved fluorescence decay study indicates that all four fullerene derivatives have a single fluorescence lifetime of ca. 1.2-1.4 as, which is about the same as that for C[sub 60] (ca. 1.3 ns). Aliphatic solvents have little influence on the absorption or fluorescence spectral profile except on the extinction coefficient whereas aromatic and polar solvents strongly interact with the fullerene derivatives, causing a peak broadening effect. 31 refs., 7 figs., 3 tabs.

  7. NEW ROOM TEMPERATURE LIQUIDS: SYNTHESIS AND CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    Macaev Fliur

    2007-06-01

    Full Text Available Room temperature ionic liquids (ILs have been recognized as a new generation of solvents for “green chemistry” and represent remarkably promising classes of technologically useful and fundamentally interesting materials [1-6]. Most of them are quaternary imidazolium cations with inorganic counterions. Cation in these salts is appended to the organic group (usually saturated hydrocarbon fragments. However, some problems regarding the functionalization [2,7], coordination properties [4] of ILs still remain to be solved. It seems to us that functionalization of imidazoles by ethylcarbonitrile, allyl, 2,3-epoxypropyl fragments will lead to new properties of synthesized ILs. There are no literature data on use of 2-(1H-1-imidazolylethylcarbonitrile 4 for synthesis of imidazolium salts with ILs properties.

  8. Structure of room temperature ionic liquids

    Science.gov (United States)

    Yethiraj, Arun

    2016-10-01

    The structure of room temperature ionic liquids is studied using molecular dynamics simulations and integral equation theory. Three ionic liquids 1-alkyl-3-methylimidazolium hexfluorophosphate, [C n MIM] [PF6], for n  =  1, 4, and 8, are studied using a united atom model of the ions. The primary interest is a study of the pair correlation functions and a test of the reference interaction site model theory. There is liquid-like ordering in the liquid that arises from electrostatic attractions and steric packing considerations. The theory is not in quantitative agreement with the simulation results and underestimates the degree of liquid-like order. A pre-peak in the static structure factor is seen in both simulations and theory, suggesting that this is a geometric effect arising from a packing of the alkyl chains.

  9. A Harsh Environment-Oriented Wireless Passive Temperature Sensor Realized by LTCC Technology

    Directory of Open Access Journals (Sweden)

    Qiulin Tan

    2014-03-01

    Full Text Available To meet measurement needs in harsh environments, such as high temperature and rotating applications, a wireless passive Low Temperature Co-fired Ceramics (LTCC temperature sensor based on ferroelectric dielectric material is presented in this paper. As a LC circuit which consists of electrically connected temperature sensitive capacitor and invariable planar spiral inductor, the sensor has its resonant frequency shift with the variation in temperature. Within near-filed coupling distance, the variation in resonant frequency of the sensor can be detected contactlessly by extracting the impedance parameters of an external antenna. Ferroelectric ceramic, which has temperature sensitive permittivity, is used as the dielectric. The fabrication process of the sensor, which differs from conventional LTCC technology, is described in detail. The sensor is tested three times from room temperature to 700 °C, and considerable repeatability and sensitivity are shown, thus the feasibility of high performance wireless passive temperature sensor realized by LTCC technology is demonstrated.

  10. A harsh environment-oriented wireless passive temperature sensor realized by LTCC technology.

    Science.gov (United States)

    Tan, Qiulin; Luo, Tao; Xiong, Jijun; Kang, Hao; Ji, Xiaxia; Zhang, Yang; Yang, Mingliang; Wang, Xiaolong; Xue, Chenyang; Liu, Jun; Zhang, Wendong

    2014-03-03

    To meet measurement needs in harsh environments, such as high temperature and rotating applications, a wireless passive Low Temperature Co-fired Ceramics (LTCC) temperature sensor based on ferroelectric dielectric material is presented in this paper. As a LC circuit which consists of electrically connected temperature sensitive capacitor and invariable planar spiral inductor, the sensor has its resonant frequency shift with the variation in temperature. Within near-filed coupling distance, the variation in resonant frequency of the sensor can be detected contactlessly by extracting the impedance parameters of an external antenna. Ferroelectric ceramic, which has temperature sensitive permittivity, is used as the dielectric. The fabrication process of the sensor, which differs from conventional LTCC technology, is described in detail. The sensor is tested three times from room temperature to 700 °C, and considerable repeatability and sensitivity are shown, thus the feasibility of high performance wireless passive temperature sensor realized by LTCC technology is demonstrated.

  11. Electrorecovery of actinides at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Stoll, Michael E [Los Alamos National Laboratory; Oldham, Warren J [Los Alamos National Laboratory; Costa, David A [Los Alamos National Laboratory

    2008-01-01

    There are a large number of purification and processing operations involving actinide species that rely on high-temperature molten salts as the solvent medium. One such application is the electrorefining of impure actinide metals to provide high purity material for subsequent applications. There are some drawbacks to the electrodeposition of actinides in molten salts including relatively low yields, lack of accurate potential control, maintaining efficiency in a highly corrosive environment, and failed runs. With these issues in mind we have been investigating the electrodeposition of actinide metals, mainly uranium, from room temperature ionic liquids (RTILs) and relatively high-boiling organic solvents. The RTILs we have focused on are comprised of 1,3-dialkylimidazolium or quaternary ammonium cations and mainly the {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anion [bis(trif1uoromethylsulfonyl)imide {equivalent_to} {sup -}NTf{sub 2}]. These materials represent a class of solvents that possess great potential for use in applications employing electrochemical procedures. In order to ascertain the feasibility of using RTILs for bulk electrodeposition of actinide metals our research team has been exploring the electron transfer behavior of simple coordination complexes of uranium dissolved in the RTIL solutions. More recently we have begun some fundamental electrochemical studies on the behavior of uranium and plutonium complexes in the organic solvents N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO). Our most recent results concerning electrodeposition will be presented in this account. The electrochemical behavior of U(IV) and U(III) species in RTILs and the relatively low vapor pressure solvents NMP and DMSO is described. These studies have been ongoing in our laboratory to uncover conditions that will lead to the successful bulk electrodeposition of actinide metals at a working electrode surface at room temperature or slightly elevated temperatures. The RTILs we

  12. Room temperature quantum emission from cubic silicon carbide nanoparticles.

    Science.gov (United States)

    Castelletto, Stefania; Johnson, Brett C; Zachreson, Cameron; Beke, David; Balogh, István; Ohshima, Takeshi; Aharonovich, Igor; Gali, Adam

    2014-08-26

    The photoluminescence (PL) arising from silicon carbide nanoparticles has so far been associated with the quantum confinement effect or to radiative transitions between electronically active surface states. In this work we show that cubic phase silicon carbide nanoparticles with diameters in the range 45-500 nm can host other point defects responsible for photoinduced intrabandgap PL. We demonstrate that these nanoparticles exhibit single photon emission at room temperature with record saturation count rates of 7 × 10(6) counts/s. The realization of nonclassical emission from SiC nanoparticles extends their potential use from fluorescence biomarker beads to optically active quantum elements for next generation quantum sensing and nanophotonics. The single photon emission is related to single isolated SiC defects that give rise to states within the bandgap.

  13. Preparation of Carbon Nanosheets at Room Temperature.

    Science.gov (United States)

    Schrettl, Stephen; Schulte, Bjoern; Stefaniu, Cristina; Oliveira, Joana; Brezesinski, Gerald; Frauenrath, Holger

    2016-03-08

    Amphiphilic molecules equipped with a reactive, carbon-rich "oligoyne" segment consisting of conjugated carbon-carbon triple bonds self-assemble into defined aggregates in aqueous media and at the air-water interface. In the aggregated state, the oligoynes can then be carbonized under mild conditions while preserving the morphology and the embedded chemical functionalization. This novel approach provides direct access to functionalized carbon nanomaterials. In this article, we present a synthetic approach that allows us to prepare hexayne carboxylate amphiphiles as carbon-rich siblings of typical fatty acid esters through a series of repeated bromination and Negishi-type cross-coupling reactions. The obtained compounds are designed to self-assemble into monolayers at the air-water interface, and we show how this can be achieved in a Langmuir trough. Thus, compression of the molecules at the air-water interface triggers the film formation and leads to a densely packed layer of the molecules. The complete carbonization of the films at the air-water interface is then accomplished by cross-linking of the hexayne layer at room temperature, using UV irradiation as a mild external stimulus. The changes in the layer during this process can be monitored with the help of infrared reflection-absorption spectroscopy and Brewster angle microscopy. Moreover, a transfer of the carbonized films onto solid substrates by the Langmuir-Blodgett technique has enabled us to prove that they were carbon nanosheets with lateral dimensions on the order of centimeters.

  14. Titanium nitride room-temperature ferromagnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Iu.G., E-mail: morozov@ism.ac.ru [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, 8 Academician Osipyan Street, Chernogolovka, Moscow Region, 142432 (Russian Federation); Belousova, O.V. [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, 8 Academician Osipyan Street, Chernogolovka, Moscow Region, 142432 (Russian Federation); Belyakov, O.A. [Ogarev Mordovia State University, Saransk, 68 Bol' shevistskaya Street, 430005 (Russian Federation); Parkin, I.P., E-mail: i.p.parkin@ucl.ac.uk [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Sathasivam, S. [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Kuznetcov, M.V., E-mail: maxim1968@mail.ru [All-Russian Research Institute on Problems of Civil Defense and Emergencies of Emergency Control Ministry of Russia (EMERCOM), 7 Davidkovskaya Street, Moscow, 121352 (Russian Federation)

    2016-08-05

    Cubic and near-spherical TiN nanoparticles ranging in average size from 20 to 125 nm were prepared by levitation-jet aerosol synthesis through condensation of titanium vapor in an inert gas flow with gaseous nitrogen injection. The nanoparticles were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), BET measurements, UV–Vis, FT-IR, Raman spectroscopy, XPS, and vibrating-sample magnetometry. Room-temperature ferromagnetism with maximum magnetization up to 2.5 emu/g was recorded for the nanoparticles. The results indicate that the observed ferromagnetic ordering was related to the defect Ti–N structures on the surface of nanoparticles. This suggestion is in good correlation with the measured spectroscopical data. - Highlights: • Levitation-jet aerosol synthesis of TiN nanoparticles (NPs). • SEM, XRD, BET, UV–vis, FT-IR, Raman, XPS and magnetic characterization of the NPs. • Correlation between optical and XPS measurements data and maximum magnetization of the NPs.

  15. Vertical Distribution of Air Temperatures in Heated Dwelling Rooms

    OpenAIRE

    Šikula, Ondřej

    2007-01-01

    The paper presents an experimental and theoretic research on one of factors influencing the indoor climate in dwelling rooms heated by heating systems, the vertical distribution of temperatures. The paper summarizes results from simulation of the room heated by a gas space heater and a plate radiator. Among main factors causing unfavorable distribution of temperatures in a room belong insufficient elimination of cold dropping airflows and high temperature of heating air. The paper presents...

  16. Optical-fiber distributed temperature sensor: design and realization

    Institute of Scientific and Technical Information of China (English)

    MENG Ling; JIANG Mingshun; SUI Qing-mei; FENG De-jun

    2008-01-01

    Through analyzing theoretically the temperature effect of the optical-fiber Raman backscattering, a distributed temperaturesensor is designed based on the single-mode fiber. Demodulation methods of temperature transduction are compared, andthen the demodulation method using the ratio of the anti-Stokes and the Stokes Raman backscattering intensity is adopted.Both the hardware composition and the software realization of the system are introduced in detail.The experiment showsthat the distinguishing ability of the temperature and that of the space are 1℃ and 2 m, respectively, and that the systemresponse time is about 180 s with a sensing range of 5 km and with a temperature measurement range of 0-100℃.

  17. Compton imager using room temperature silicon detectors

    Science.gov (United States)

    Kurfess, James D.; Novikova, Elena I.; Phlips, Bernard F.; Wulf, Eric A.

    2007-08-01

    We have been developing a multi-layer Compton Gamma Ray Imager using position-sensitive, intrinsic silicon detectors. Advantages of this approach include room temperature operation, reduced Doppler broadening, and use of conventional silicon fabrication technologies. We have obtained results on the imaging performance of a multi-layer instrument where each layer consists of a 2×2 array of double-sided strip detectors. Each detector is 63 mm×63 mm×2 mm thick and has 64 strips providing a strip pitch of approximately 0.9 mm. The detectors were fabricated by SINTEF ICT (Oslo Norway) from 100 mm diameter wafers. The use of large arrays of silicon detectors appears especially advantageous for applications that require excellent sensitivity, spectral resolution and imaging such as gamma ray astrophysics, detection of special nuclear materials, and medical imaging. The multiple Compton interactions (three or more) in the low-Z silicon enable the energy and direction of the incident gamma ray to be determined without full deposition of the incident gamma-ray energy in the detector. The performance of large volume instruments for various applications are presented, including an instrument under consideration for NASA's Advanced Compton Telescope (ACT) mission and applications to Homeland Security. Technology developments that could further extend the sensitivity and performance of silicon Compton Imagers are presented, including the use of low-energy (few hundred keV) electron tracking within novel silicon detectors and the potential for a wafer-bonding approach to produce thicker, position-sensitive silicon detectors with an associated reduction of required electronics and instrument cost.

  18. Room temperature micro-hydrogen-generator

    Science.gov (United States)

    Gervasio, Don; Tasic, Sonja; Zenhausern, Frederic

    A new compact and cost-effective hydrogen-gas generator has been made that is well suited for supplying hydrogen to a fuel-cell for providing base electrical power to hand-carried appliances. This hydrogen-generator operates at room temperature, ambient pressure and is orientation-independent. The hydrogen-gas is generated by the heterogeneous catalytic hydrolysis of aqueous alkaline borohydride solution as it flows into a micro-reactor. This reactor has a membrane as one wall. Using the membrane keeps the liquid in the reactor, but allows the hydrogen-gas to pass out of the reactor to a fuel-cell anode. Aqueous alkaline 30 wt% borohydride solution is safe and promotes long application life, because this solution is non-toxic, non-flammable, and is a high energy-density (≥2200 W-h per liter or per kilogram) hydrogen-storage solution. The hydrogen is released from this storage-solution only when it passes over the solid catalyst surface in the reactor, so controlling the flow of the solution over the catalyst controls the rate of hydrogen-gas generation. This allows hydrogen generation to be matched to hydrogen consumption in the fuel-cell, so there is virtually no free hydrogen-gas during power generation. A hydrogen-generator scaled for a system to provide about 10 W electrical power is described here. However, the technology is expected to be scalable for systems providing power spanning from 1 W to kW levels.

  19. “A Long March to Room Temperature Superconductivity”

    CERN Document Server

    CERN. Geneva

    2015-01-01

    In the last 29 years, great progress has been made in all areas of high temperature superconductivity (HTS) research from raising the transition temperature Tc and discovering new HTS compounds to developing theoretical models of HTS and fabricating and testing HTS prototype devices. For example, the Tc has been increased to 164 K in cuprate HgBa2Ca2Cu3Ox under 30 GPa in 1993 at Houston, more than 200 HTS compounds have been found, numerous theoretical models have been developed, and many HTS prototype devices have been tested to display superior performance to that of their non-superconducting counterparts. The strong electron-phonon interaction required for the high Tc observed has been considered to be able to induce catastrophic structure collapse before high Tc can be realized, and a novel magnetism-based interaction in different forms has thus been proposed for high Tc. However, room temperature superconductivity is still elusive and a comprehensive microscopic theory of HTS remains to be achieved. The...

  20. Temperature Distribution in a Displacement Ventilated Room

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    The vertical temperature gradient is normally given as a linear temperature distribution between a minimum temperature close to the floor and a maximum temperature close to the ceiling. The minimum temperature can either be a constant fraction of a load dependent difference or it can be connected...

  1. Room-temperature semiconductors and scintillators for planetary instruments

    CERN Document Server

    Schweitzer, J S

    1999-01-01

    Room temperature semiconductors introduce some exciting potential for use in instruments designed for planetary measurements. It is important, however, to consider carefully the different types of measurement environments. In some cases room temperature semiconductors provide significant advantages over scintillators, while in some cases scintillators still have advantages over room temperature semiconductors. A number of instrumentation applications for detecting X-rays and gamma rays are considered. By focusing on the physical properties of both types of detectors, it is possible to better understand how each type of detector can best be used for measurements from satellites and directly on planetary bodies.

  2. Room temperature and productivity in office work

    Energy Technology Data Exchange (ETDEWEB)

    Seppanen, O.; Fisk, W.J.; Lei, Q.H.

    2006-07-01

    Indoor temperature is one of the fundamental characteristics of the indoor environment. It can be controlled with a degree of accuracy dependent on the building and its HVAC system. The indoor temperature affects several human responses, including thermal comfort, perceived air quality, sick building syndrome symptoms and performance at work. In this study, we focused on the effects of temperature on performance at office work. We included those studies that had used objective indicators of performance that are likely to be relevant in office type work, such as text processing, simple calculations (addition, multiplication), length of telephone customer service time, and total handling time per customer for call-center workers. We excluded data from studies of industrial work performance. We calculated from all studies the percentage of performance change per degree increase in temperature, and statistically analyzed measured work performance with temperature. The results show that performance increases with temperature up to 21-22 C, and decreases with temperature above 23-24 C. The highest productivity is at temperature of around 22 C. For example, at the temperature of 30 C, the performance is only 91.1% of the maximum i.e. the reduction in performance is 8.9%.

  3. Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride

    Science.gov (United States)

    Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature.

  4. High Power Room Temperature Terahertz Local Oscillator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to build a high-power, room temperature compact continuous wave terahertz local oscillator for driving heterodyne receivers in the 1-5 THz frequency...

  5. Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride

    Science.gov (United States)

    Baig, R. B. Nasir; Verma, Sanny; Nadagouda, Mallikarjuna N.; Varma, Rajender S.

    2016-12-01

    Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature.

  6. Workshop on the Road to Room Temperature Superconductivity

    Science.gov (United States)

    1993-01-14

    Road to Room Temperature Superconductivity A workshop was held October 19-2 1, 1992, in Bodega Bay, California, to discuss possibilities for attaining...Appendix I RTS WORKSHOP PARTICIPANTS BODEGA BAY LODGE OCTOBER 19-21, 1992 Cava, Dr. R. J. AT&T Bell Laboratories Mat’ls Sci & Engr Res Div 1T304 600 Mountain...708-252-3464 1 Attendance inderendently supported Fax:708-252-4993 Appendix 2 - Agenda THE SEARCH FOR ROOM TEMPERATURE SUPERCONDUCTIVITY Bodega Bay

  7. A silicon carbide room-temperature single-photon source

    Science.gov (United States)

    Castelletto, S.; Johnson, B. C.; Ivády, V.; Stavrias, N.; Umeda, T.; Gali, A.; Ohshima, T.

    2014-02-01

    Over the past few years, single-photon generation has been realized in numerous systems: single molecules, quantum dots, diamond colour centres and others. The generation and detection of single photons play a central role in the experimental foundation of quantum mechanics and measurement theory. An efficient and high-quality single-photon source is needed to implement quantum key distribution, quantum repeaters and photonic quantum information processing. Here we report the identification and formation of ultrabright, room-temperature, photostable single-photon sources in a device-friendly material, silicon carbide (SiC). The source is composed of an intrinsic defect, known as the carbon antisite-vacancy pair, created by carefully optimized electron irradiation and annealing of ultrapure SiC. An extreme brightness (2×106 counts s-1) resulting from polarization rules and a high quantum efficiency is obtained in the bulk without resorting to the use of a cavity or plasmonic structure. This may benefit future integrated quantum photonic devices.

  8. Airflow and Temperature Distribution in Rooms with Displacement Ventilation

    DEFF Research Database (Denmark)

    Jacobsen, T. V.

    This thesis deals with air flow and temperature distribution in a room ventilated by the displacement principle. The characteristic features of the ventilation system are treated in the whole room but main emphasis is laid on the analysis of the stratified flow region in front of the inlet device....... After a prefatory description of the background and the fundamentals of displacement ventilation the objectives of the current study are specified. The subsequent sections describe the measurements of velocity and temperature profiles carried out in a full scale test room. Based on experimental data...

  9. Irradiation dose determination below room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Bernal, S. E-mail: ramos@nuclecu.unam.mx; Cruz, E.; Negron-Mendoza, A.; Bustos, E

    2002-03-01

    The measurements presented were undertaken to provide quantitative information on the low temperature irradiation of thermoluminiscence phosphors. The crystals used were (a) LiF co-doped with Mg, Cu and P, and (b) CaSO{sub 4} doped with Dy. The absorbed dose values in the interval studied showed a linear behavior at low doses and low temperature. The aim of this work is to test if these crystals can be used to measure the dose absorbed by solids at low temperature.

  10. Room-Temperature Quantum Transport Signatures in Graphene/LaAlO3 /SrTiO3 Heterostructures.

    Science.gov (United States)

    Jnawali, Giriraj; Huang, Mengchen; Hsu, Jen-Feng; Lee, Hyungwoo; Lee, Jung-Woo; Irvin, Patrick; Eom, Chang-Beom; D'Urso, Brian; Levy, Jeremy

    2017-03-01

    High mobility graphene field-effect devices, fabricated on the complex-oxide heterostructure LaAlO3 /SrTiO3 , exhibit quantum interference signatures up to room temperature. The oxide material is believed to play a critical role in suppressing short-range and phonon contributions to scattering. The ability to maintain pseudospin coherence at room temperature holds promise for the realization of new classical and quantum information technologies.

  11. Enabling room temperature sodium metal batteries

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Ruiguo; Mushra, Kuber; Li, Xiaolin; Qian, Jiangfeng; Engelhard, Mark H.; Bowden, Mark E.; Han, Kee Sung; Mueller, Karl T.; Henderson, Wesley A.; Zhang, Jiguang

    2016-12-01

    Rechargeable batteries based upon sodium (Na+) cations are at the core of many new battery chemistries beyond Li-ion batteries. Rather than using carbon or alloy-based anodes, the direct utilization of solid sodium metal as an anode would be highly advantageous, but its use has been highly problematic due to its high reactivity. In this work, however, it is demonstrated that, by tailoring the electrolyte formulation, solid Na metal can be electrochemically plated/stripped at ambient temperature with high efficiency (> 99%) on both copper and inexpensive aluminum current collectors thereby enabling a shift in focus to new battery chemical couples based upon Na metal operating at ambient temperature. These highly concentrated electrolytes has enabled stable cycling of Na metal batteries based on a Na metal anode and Na3V2(PO4)3 cathode at high rates with very high efficiency.

  12. Possible room temperature ferromagnetism in silicon doped tellurium semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, P.K., E-mail: pkmishra@barc.gov.in [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Babu, P.D., E-mail: pdbabu@csr.res.in [UGC-DAE Consortium for Scientific Research, Mumbai Centre, BARC, Mumbai 400085 (India); Ravikumar, G. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mishra, R.; Roy, Mainak; Phapale, S. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2015-08-05

    Highlights: • In this work we report the observation of ferromagnetism in a silicon doped tellurium sample at room temperature. • Isothermal magnetization hysteresis measurements shows ferromagnetism persists up to room temperature. • We ascribe the origin of ferromagnetism to possible modification of electronic band or generation of local magnetic moment by silicon doping into the parent tellurium lattice. • Potentially this could be a new type of room-temperature magnetic semiconductor that is not based on any oxide or nitride. - Abstract: We have found direct evidence of ferromagnetism in a silicon doped tellurium sample, a new type of magnetic semiconductor that is not based on any oxide or nitride. Room temperature ferromagnetism was very apparent from the magnetization hysteresis. Isothermal magnetization hysteresis loop and differences in ZFC and FC branches of magnetization shows that the ferromagnetic transition temperature is above room temperature. Observation of magnetization hysteresis only at low magnetic fields is indicative of smaller domain size. Average estimated magnetic moment μ per domain is 2.6 μ{sub B}. The origin of ferromagnetism could be ascribed to modification of electronic band or generation of local magnetic moment by silicon doping into the parent tellurium lattice.

  13. Room temperature organic magnets derived from sp3 functionalized graphene

    Science.gov (United States)

    Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B.; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

    2017-02-01

    Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp2-conjugated diradical motifs embedded in an sp3 matrix and superexchange interactions via -OH functionalization.

  14. Room temperature organic magnets derived from sp3 functionalized graphene

    Science.gov (United States)

    Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B.; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

    2017-01-01

    Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp2-conjugated diradical motifs embedded in an sp3 matrix and superexchange interactions via –OH functionalization. PMID:28216636

  15. Nonclassical Photon Pairs Generated from a Room-temperature Atomic Ensemble

    Institute of Scientific and Technical Information of China (English)

    JIANG Wei; HAN Chao; XUE Peng; DUAN L M; GUO G C

    2004-01-01

    @@ We report experimental generation of non-classically correlated photon pairs from collective emission in a room temperature atomic vapor cell.The nonclassical feature of the emission is demonstrated by observing a violation of the Cauchy-Schwarz inequality.Each pair of correlated photons are separated by a controllable time delay up to 2 microseconds.This experiment demonstrates an important step towards the realization of the Duan-Lukin-Cirac-Zoller scheme for scalable long-distance quantum communication.

  16. Room temperature triggered single-photon source in the near infrared

    Energy Technology Data Exchange (ETDEWEB)

    Wu, E [Laboratoire de Photonique Quantique et Moleculaire, UMR CNRS 8537, Ecole Normale Superieure de Cachan (France); Rabeau, J R [Department of Physics, Macquarie University, Sydney, New South Wales 2109 (Australia); Roger, G [Laboratoire Charles Fabry de l' Institut d' Optique, UMR CNRS 8501, Palaiseau (France); Treussart, F [Laboratoire de Photonique Quantique et Moleculaire, UMR CNRS 8537, Ecole Normale Superieure de Cachan (France); Zeng, H [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China (China); Grangier, P [Laboratoire Charles Fabry de l' Institut d' Optique, UMR CNRS 8501, Palaiseau (France); Prawer, S [Centre of Excellence for Quantum Computer Technology and Quantum Communications Victoria, School of Physics, University of Melbourne, Victoria 3010 (Australia); Roch, J-F [Laboratoire de Photonique Quantique et Moleculaire, UMR CNRS 8537, Ecole Normale Superieure de Cachan (France)

    2007-12-15

    We report the realization of a solid-state triggered single-photon source with narrow emission in the near infrared at room temperature. It is based on the photoluminescence of a single nickel-nitrogen NE8 colour centre in a chemical vapour deposited diamond nanocrystal. Stable single-photon emission has been observed in the photoluminescence under both continuous-wave and pulsed excitations. The realization of this source represents a step forward in the application of diamond-based single-photon sources to quantum key distribution (QKD) under practical operating conditions.

  17. Simple Room Temperature Method for Polymer Optical Fibre Cleaving

    DEFF Research Database (Denmark)

    Saez-Rodriguez, David; Nielsen, Kristian; Bang, Ole

    2015-01-01

    . In this paper, we make use of the temperature-time equivalence in polymers to replace the use of heating by an increase of the cleaving time and use a sawing motion to reduce fibre end face damage. In this way, the polymer fibre can be cleaved at room temperature in seconds with the resulting end face being...

  18. Vertical Temperature Distribution in a Room with Displacement Ventilation

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    A displacement ventilation system exploits the use of energy efficiently because it is possible to remove exhaust air from a room with a temperature that is several degrees above the temperature in the occupied zone. This process will allow a higher air inlet temperature at the same load...... to consider the temperature gradient in the occupied zone, as well as the asymmetric radiation from the ceiling, in connection with the design of a displacement ventilation system and the evaluation of thermal comfort. This paper will introduce five temperature distribution models with different levels...... in comparison with mixing ventilation. It is necessary to have a design method for the temperature distribution used for instance in connection with the tlow element method and the energy calculations. The temperature distribution is also important in connection with thermal comfort in a room. It is necessary...

  19. A novel magnetic valve using room temperature magnetocaloric materials

    DEFF Research Database (Denmark)

    Eriksen, Dan; Bahl, Christian; Pryds, Nini;

    2012-01-01

    Magnetocaloric materials with near-room-temperature tuneable Curie temperatures have been utilized to develop a novel magnetic valve technology. The temperature dependent attractive force between the materials and a permanent magnet assembly is used to actuate valves as a response to temperature...... changes. This is made possible by the strong temperature dependence of the magnetization close to the Curie temperature of the magnetocaloric materials. Different compositions of both La0.67(Ca,Sr)0.33MnO3 and La(Fe,Co,Si)13 have been considered for use in prototype valves. Based on measured magnetization...

  20. Geologically-inspired strong bulk ceramics made with water at room temperature

    Science.gov (United States)

    Bouville, Florian; Studart, André R.

    2017-03-01

    Dense ceramic materials can form in nature under mild temperatures in water. By contrast, man-made ceramics often require sintering temperatures in excess of 1,400 °C for densification. Chemical strategies inspired by biomineralization processes have been demonstrated but remain limited to the fabrication of thin films and particles. Besides biomineralization, the formation of dense ceramic-like materials such as limestone also occurs in nature through large-scale geological processes. Inspired by the geological compaction of mineral sediments in nature, we report a room-temperature method to produce dense and strong ceramics within timescales comparable to those of conventional manufacturing processes. Using nanoscale powders and high compaction pressures, we show that such cold sintering process can be realized with water at room temperature to result in centimetre-sized bulk parts with specific strength that is comparable to, and occasionally even higher than, that of traditional structural materials like concrete.

  1. Geologically-inspired strong bulk ceramics made with water at room temperature

    Science.gov (United States)

    Bouville, Florian; Studart, André R.

    2017-01-01

    Dense ceramic materials can form in nature under mild temperatures in water. By contrast, man-made ceramics often require sintering temperatures in excess of 1,400 °C for densification. Chemical strategies inspired by biomineralization processes have been demonstrated but remain limited to the fabrication of thin films and particles. Besides biomineralization, the formation of dense ceramic-like materials such as limestone also occurs in nature through large-scale geological processes. Inspired by the geological compaction of mineral sediments in nature, we report a room-temperature method to produce dense and strong ceramics within timescales comparable to those of conventional manufacturing processes. Using nanoscale powders and high compaction pressures, we show that such cold sintering process can be realized with water at room temperature to result in centimetre-sized bulk parts with specific strength that is comparable to, and occasionally even higher than, that of traditional structural materials like concrete. PMID:28262760

  2. Development of DMC controllers for temperature control of a room deploying the displacement ventilation HVAC system

    Directory of Open Access Journals (Sweden)

    Zhicheng Li, Ramesh K. Agarwal, Huijun Gao

    2013-01-01

    Full Text Available In this paper, by developing a new Dynamic Matrix Control (DMC method, we develop a controller for temperature control of a room cooled by a displacement ventilation HVAC system. The fluid flow and heat transfer inside the room are calculated by solving the Reynolds-Averaged Navier-Stokes (RANS equations including the effects of buoyancy in conjunction with a two-equation realizable k - epsilon turbulence model. Thus the physical environment is represented by a nonlinear system of partial differential equations. The system also has a large time delay because of the slowness of the heat exchange. The goal of the paper is to develop a controller that will maintain the temperature at three points near three different walls in a room within the specified upper and lower bounds. In order to solve this temperature control problem at three different points in the room, we develop a special DMC method. The results show that the newly developed DMC controller is an effective controller to maintain temperature within desired bounds at multiple points in the room and also saves energy when compared to other controllers. This DMC method can also be employed to develop controllers for other HVAC systems such as the overhead VAV (Variable Air Volume system and the radiant cooling hydronic system.

  3. Development of DMC controllers for temperature control of a room deploying the displacement ventilation HVAC system

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhicheng; Agarwal, Ramesh K. [Department of Mechanical Engineering and Materials Science, Washington University in Saint Louis, MO 63130 (United States); Gao, Huijun [Research Institute of Intelligent Control and Systems, Harbin Institute of Technology, Harbin 150001 (China)

    2013-07-01

    In this paper, by developing a new Dynamic Matrix Control (DMC) method, we develop a controller for temperature control of a room cooled by a displacement ventilation HVAC system. The fluid flow and heat transfer inside the room are calculated by solving the Reynolds-Averaged Navier-Stokes (RANS) equations including the effects of buoyancy in conjunction with a two-equation realizable k - epsilon turbulence model. Thus the physical environment is represented by a nonlinear system of partial differential equations. The system also has a large time delay because of the slowness of the heat exchange. The goal of the paper is to develop a controller that will maintain the temperature at three points near three different walls in a room within the specified upper and lower bounds. In order to solve this temperature control problem at three different points in the room, we develop a special DMC method. The results show that the newly developed DMC controller is an effective controller to maintain temperature within desired bounds at multiple points in the room and also saves energy when compared to other controllers. This DMC method can also be employed to develop controllers for other HVAC systems such as the overhead VAV (Variable Air Volume) system and the radiant cooling hydronic system.

  4. Giant room-temperature elastocaloric effect in ferroelectric ultrathin films.

    Science.gov (United States)

    Liu, Yang; Infante, Ingrid C; Lou, Xiaojie; Bellaiche, Laurent; Scott, James F; Dkhil, Brahim

    2014-09-17

    Environmentally friendly ultrathin BaTiO3 capacitors can exhibit a giant stress-induced elastocaloric effect without hysteresis loss or Joule heating. By combining this novel elastocaloric effect with the intrinsic electrocaloric effect, an ideal refrigeration cycle with high performance (temperature change over 10 K with a wide working-temperature window of 60 K) at room temperature is proposed for future cooling applications.

  5. Ultrahigh magnetoresistance at room temperature in molecular wires.

    Science.gov (United States)

    Mahato, R N; Lülf, H; Siekman, M H; Kersten, S P; Bobbert, P A; de Jong, M P; De Cola, L; van der Wiel, W G

    2013-07-19

    Systems featuring large magnetoresistance (MR) at room temperature and in small magnetic fields are attractive owing to their potential for applications in magnetic field sensing and data storage. Usually, the magnetic properties of materials are exploited to achieve large MR effects. Here, we report on an exceptionally large (>2000%), room-temperature, small-field (a few millitesla) MR effect in one-dimensional, nonmagnetic systems formed by molecular wires embedded in a zeolite host crystal. This ultrahigh MR effect is ascribed to spin blockade in one-dimensional electron transport. Its generic nature offers very good perspectives to exploit the effect in a wide range of low-dimensional systems.

  6. Scintillation yield of liquid xenon at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ueshima, K. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan)], E-mail: ueshima@suketto.icrr.u-tokyo.ac.jp; Abe, K.; Iida, T.; Ikeda, M.; Kobayashi, K.; Koshio, Y.; Minamino, A.; Miura, M.; Moriyama, S. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Nakahata, M. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Nakajima, Y.; Ogawa, H.; Sekiya, H.; Shiozawa, M. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Suzuki, Y. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Takeda, A.; Takeuchi, Y.; Yamashita, M. [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo, Kamioka, Hida, Gifu 506-1205 (Japan); Kaneyuki, K. [Research Center for Cosmic Neutrinos, Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Doke, T. [Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Tokyo 162-8555 (Japan)] (and others)

    2008-09-01

    The intensity of scintillation light emission from liquid xenon at room temperature was measured. The scintillation light yield at 1{sup 0}C was measured to be 0.64{+-}0.02 (stat.) {+-}0.06 (sys.) of that at -100{sup 0}C. Using the reported light yield at -100{sup 0}C (46 photons/keV), the measured light yield at 1{sup 0}C corresponds to 29 photons/keV. This result shows that liquid xenon scintillator provides high light yield even at room temperature.

  7. Room temperature mid-IR single photon spectral imaging

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2012-01-01

    modern Quantum cascade lasers have evolved as ideal coherent mid-IR excitation sources, simple, low noise, room temperature detectors and imaging systems still lag behind. We address this need presenting a novel, field-deployable, upconversion system for sensitive, 2-D, mid-IR spectral imaging. Measured...... room temperature dark noise is 0.2 photons/spatial element/second, which is a billion times below the dark noise level of cryogenically cooled InSb cameras. Single photon imaging and up to 200 x 100 spatial elements resolution is obtained reaching record high continuous wave quantum efficiency of about...

  8. Green monolithic II-VI vertical-cavity surface-emitting laser operating at room temperature

    Science.gov (United States)

    Kruse, C.; Ulrich, S. M.; Alexe, G.; Roventa, E.; Kröger, R.; Brendemühl, B.; Michler, P.; Gutowski, J.; Hommel, D.

    2004-02-01

    The realization of a monolithic all II-VI-based vertical cavity surface emitting laser (VCSEL) for the green spectral region is reported. Optically pumped lasing operation was achieved up to room temperature using a planar VCSEL structure. Taking advantage of distributed Bragg-reflectors based on MgS/Zn(Cd)Se superlattices as the low-refractive index material and ZnS0.06Se0.94 layers as the high-index material with a refractive index contrast of n = 0.6, a quality factor exceeding Q = 2000 is reached by using only 18 Bragg periods for the bottom DBR and 15 Bragg periods for the top DBR. The threshold power density is 0.32 MW/cm2 at a temperature of 10 K (emission wavelength 498.5 nm) and 1.9 MW/cm2 at room temperature (emission wavelength 502.3 nm).

  9. Zn-Mn-O: Ferromagnet at room temperature

    Directory of Open Access Journals (Sweden)

    Milivojević Dušan D.

    2007-01-01

    Full Text Available Semiconductor Zn-Mn-O crystallites were synthesized by a solid state reaction method starting from the thermal decomposition of the appropriate oxalates. Samples were thermally treated in air at temperatures ranging from 400 to 900°C. The nominal concentrations of manganese werex = 0.01, 0.02, 0.04 and 0.10. The samples were investigated by the X-ray powder diffraction method, magnetization measurements and by electron paramagnetic resonance. X-ray diffractgrams show a dominant wurtzite structure of Zn-Mn-O. Room temperature ferromagnetism was observed in Zn-Mn-O samples with manganese concentrations x ≤ 0.04, thermally treated at low temperature (500°C. The saturation magnetiza­tion for the sample with x = 0.01 was 0.05 μB/Mn. The room temperature ferromagnetism seems to be due to the diffusion of Zn into the Mn-oxides grains.

  10. Amination of allylic alcohols in water at room temperature.

    Science.gov (United States)

    Nishikata, Takashi; Lipshutz, Bruce H

    2009-06-04

    The "trick" to carrying out regiocontrolled aminations of allylic alcohols in water as the only medium is use of a nanomicelle's interior as the organic reaction solvent. When HCO(2)Me is present, along with the proper base and source of catalytic Pd, allylic amines are cleanly formed at room temperature.

  11. Required Be Capsule Strength For Room Temperature Transport

    Energy Technology Data Exchange (ETDEWEB)

    Cook, B

    2005-03-21

    The purpose of this memo is to lay out the criteria for the Be capsule strength necessary for room temperature transport. Ultimately we will test full thickness capsules by sealing high pressures inside, but currently we are limited to both thinner capsules and alternative measures of capsule material strength.

  12. Room-Temperature Ionic Liquids for Electrochemical Capacitors

    Science.gov (United States)

    Fireman, Heather; Yowell, Leonard; Moloney, Padraig G.; Arepalli, Sivaram; Nikolaev, P.; Huffman, C.; Ready, Jud; Higgins, C.D.; Turano, S. P.; Kohl, P.A.; Kim, K.

    2009-01-01

    A document discusses room-temperature ionic liquids (RTILs) used as electrolytes in carbon-nanotube-based, electrochemical, double-layer capacitors. Unlike the previous electrolyte (EtNB4 in acetonitrile), the RTIL used here does not produce cyanide upon thermal decomposition and does not have a moisture sensitivity.

  13. Tribochemical Decomposition of Light Ionic Hydrides at Room Temperature.

    Science.gov (United States)

    Nevshupa, Roman; Ares, Jose Ramón; Fernández, Jose Francisco; Del Campo, Adolfo; Roman, Elisa

    2015-07-16

    Tribochemical decomposition of magnesium hydride (MgH2) induced by deformation at room temperature was studied on a micrometric scale, in situ and in real time. During deformation, a near-full depletion of hydrogen in the micrometric affected zone is observed through an instantaneous (t MgH2 with reduced crystal size by mechanical deformation.

  14. Coulomb blockade and Coulomb staircase behavior observed at room temperature

    Science.gov (United States)

    Uky Vivitasari, Pipit; Azuma, Yasuo; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka

    2017-02-01

    A single-electron transistor (SET) consists of source, drain, Coulomb island, and gate to modulate the number of electrons and control the current. For practical applications, it is important to operate a SET at room temperature. One proposal towards the ability to operate at room temperature is to decrease Coulomb island size down to a few nanometres. We investigate a SET using Sn-porphyrin (Sn-por) protected gold nanoparticles (AuNPs) with 1.4 nm in core diameter as a Coulomb island. The fabrication method of nanogap electrodes uses the combination of a top-down technique by electron beam lithography (EBL) and a bottom-up process through electroless gold plating (ELGP) as our group have described before. The electrical measurement was conducted at room temperature (300 K). From current-voltage (I d-V d) characteristics, we obtained clear Coulomb blockade phenomena together with a Coulomb staircase due to a Sn-por protected gold NP as a Coulomb island. Experimental results of I d-V d characteristics agree with a theoretical curve based on using the orthodox model. Clear dI d/dV d peaks are observed in the Coulomb staircase at 9 K which suggest the electron transports through excited energy levels of Au NPs. These results are a big step for obtaining SETs that can operate at room temperature.

  15. COPPER(0)-MEDIATED RADICAL POLYMERIZATION OF STYRENE AT ROOM TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    Xiao-fei Zhang; Yang Wu; Jun Huang; Xue-lang Miao; Zheng-biao Zhang; Xiu-lin Zhu

    2013-01-01

    The "living'/controlled radical polymerization (LRP) of styrene (St) at room temperature is rarely reported.In this work,copper(0) (Cu(0))-mediated radical polymerization of St at room temperature was investigated in detail.Dimethyl sulfoxide (DMSO),N,N-dimethylformamide (DMF) as well as a binary solvent,tetrahydrofuran/1,1,1,3,3,3-hexafluoro-2-propanol were used as the solvents,respectively.Methyl-2-bromopropionate and ethyl 2-bromoisobutyrate were used as the initiators,respectively.The polymerization proceeded smoothly with moderate conversions at room temperature.It was found that DMF was a good solvent with the essential features of LRP,while DMSO was a poor solvent with uncontrollable molecular weights.Besides,the match among the initiator,solvent and molar ratios of reactants can modulate the livingness of the polymerization,and the proper selection of ligand was also crucial to a controlled process.This work provided a first example of Cu(0)-mediated radical polymerization of St at room temperature,which would enrich and strength the LRP technique.

  16. Evaluation of Ceramic Honeycomb Core Compression Behavior at Room Temperature

    Science.gov (United States)

    Bird, Richard K.; Lapointe, Thomas S.

    2013-01-01

    Room temperature flatwise compression tests were conducted on two varieties of ceramic honeycomb core specimens that have potential for high-temperature structural applications. One set of specimens was fabricated using strips of a commercially-available thin-gage "ceramic paper" sheet molded into a hexagonal core configuration. The other set was fabricated by machining honeycomb core directly from a commercially available rigid insulation tile material. This paper summarizes the results from these tests.

  17. Giant Magnetic Entropy Change in Manganese Perovskites near Room Temperature

    Institute of Scientific and Technical Information of China (English)

    钟伟; 王锦辉; 都有为; 陈伟

    2001-01-01

    A large magnetic entropy change about twice as high as that of pure gadolinium metal near room temperature has been discovered in manganese perovskites La0.837Ca0.098Na0.03sMn0.987O3.00(8.3 J. kg-1.K-1, at 256 K) and La0.s22Ca0.096K0.043Mn0.974O3.00 (6.8 J. kg-1.K-1, at 265K) under a magnetic field of 1.5 T. This phenomenon indicates that manganese perovskites have potential applications for magnetic refrigerants in an extended temperature range even near room temperature.

  18. Room Temperature Characterization of a Magnetic Bearing for Turbomachinery

    Science.gov (United States)

    Montague, Gerald; Jansen, Mark; Provenza, Andrew; Jansen, Ralph; Ebihara, Ben; Palazzolo, Alan

    2002-01-01

    Open loop, experimental force and power measurements of a three-axis, radial, heteropolar magnetic bearing at room temperature for rotor speeds up to 20,000 RPM are presented in this paper. The bearing, NASA Glenn Research Center's and Texas A&M's third generation high temperature magnetic bearing, was designed to operate in a 1000 F (540 C) environment and was primarily optimized for maximum load capacity. The experimentally measured force produced by one C-core of this bearing was 630 lb. (2.8 kN) at 16 A, while a load of 650 lbs (2.89 kN) was predicted at 16 A using 1D circuit analysis. The maximum predicted radial load for one of the three axes is 1,440 lbs (6.41 kN) at room temperature. The maximum measured load of an axis was 1050 lbs. (4.73 kN). Results of test under rotating conditions showed that rotor speed has a negligible effect on the bearing's load capacity. A single C-core required approximately 70 W of power to generate 300 lb (1.34 kN) of magnetic force. The room temperature data presented was measured after three thermal cycles up to 1000 F (540 C), totaling six hours at elevated temperatures.

  19. Room-Temperature Deposition of NbN Superconducting Films

    Science.gov (United States)

    Thakoor, S.; Lamb, J. L.; Thakoor, A. P.; Khanna, S. K.

    1986-01-01

    Films with high superconducting transition temperatures deposited by reactive magnetron sputtering. Since deposition process does not involve significantly high substrate temperatures, employed to deposit counter electrode in superconductor/insulator/superconductor junction without causing any thermal or mechanical degradation of underlying delicate tunneling barrier. Substrates for room-temperature deposition of NbN polymeric or coated with photoresist, making films accessible to conventional lithographic patterning techniques. Further refinements in deposition technique yield films with smaller transition widths, Tc of which might approach predicted value of 18 K.

  20. Quantum correlations of light due to a room temperature mechanical oscillator

    CERN Document Server

    Sudhir, Vivishek; Fedorov, Sergey A; Schuetz, Hendrik; Wilson, Dalziel J; Kippenberg, Tobias J

    2016-01-01

    The coupling of laser light to a mechanical oscillator via radiation pressure leads to the emergence of quantum mechanical correlations in the amplitude and phase quadrature of the laser beam. These correlations form a generic non-classical quantum resource which can be employed for quantum enhanced force metrology, and gives rise to ponderomotive squeezing in the limit of strong correlations. To date, this resource has only been observed in a handful of cryogenic cavity optomechanical experiments. Here, we demonstrate the ability to efficiently resolve optomechanical quantum correlations imprinted on an optical laser beam interacting with a room temperature nanomechanical oscillator. Direct measurement of the optical beam in a detuned homodyne detector ("variational readout") at frequencies far from the resonance frequency of the oscillator, reveal quantum correlations at a few percent level. We use these correlations to realize a $7\\%$ quantum-enhancement in thermal force estimation at room temperature. The...

  1. Cryopreservation of Byrsonima intermedia embryos followed by room temperature thawing

    Directory of Open Access Journals (Sweden)

    Luciano Coutinho Silva

    2014-07-01

    Full Text Available Byrsonima intermedia is a shrub from the Brazilian Cerrado with medicinal properties. The storage of biological material at ultra-low temperatures (-196°C is termed cryopreservation and represents a promising technique for preserving plant diversity. Thawing is a crucial step that follows cryopreservation. The aim of this work was to cryopreserve B. intermedia zygotic embryos and subsequently thaw them at room temperature in a solution rich in sucrose. The embryos were decontaminated and desiccated in a laminar airflow hood for 0-4 hours prior to plunging into liquid nitrogen. The embryo moisture content (% MC during dehydration was assessed. Cryopreserved embryos were thawed in a solution rich in sucrose at room temperature, inoculated in a germination medium and maintained in a growth chamber. After 30 days, the embryo germination was evaluated. No significant differences were observed between the different embryo dehydration times, where they were dehydrated for at least one hour. Embryos with a MC between 34.3 and 20.3% were germinated after cryopreservation. In the absence of dehydration, all embryos died following cryopreservation. We conclude that B. intermedia zygotic embryos can be successfully cryopreserved and thawed at room temperature after at least one hour of dehydration in a laminar airflow bench.

  2. Scalable architecture for a room temperature solid-state quantum information processor.

    Science.gov (United States)

    Yao, N Y; Jiang, L; Gorshkov, A V; Maurer, P C; Giedke, G; Cirac, J I; Lukin, M D

    2012-04-24

    The realization of a scalable quantum information processor has emerged over the past decade as one of the central challenges at the interface of fundamental science and engineering. Here we propose and analyse an architecture for a scalable, solid-state quantum information processor capable of operating at room temperature. Our approach is based on recent experimental advances involving nitrogen-vacancy colour centres in diamond. In particular, we demonstrate that the multiple challenges associated with operation at ambient temperature, individual addressing at the nanoscale, strong qubit coupling, robustness against disorder and low decoherence rates can be simultaneously achieved under realistic, experimentally relevant conditions. The architecture uses a novel approach to quantum information transfer and includes a hierarchy of control at successive length scales. Moreover, it alleviates the stringent constraints currently limiting the realization of scalable quantum processors and will provide fundamental insights into the physics of non-equilibrium many-body quantum systems.

  3. Synthesis of cadmium chalcogenide nanotubes at room temperature

    KAUST Repository

    Pan, Jun

    2012-10-01

    Cadmium chalcogenide (CdE, E=S, Se, Te) polycrystalline nanotubes have been synthesized from precursor of CdS/cadmium thiolate complex at room temperature. The precursor was hydrothermally synthesized at 180 °C using thioglycolic acid (TGA) and cadmium acetate as starting materials. The transformation from the rod-like precursor of CdS/cadmium thiolate complex to CdS, CdSe and CdTe nanotubes were performed under constant stirring at room temperature in aqueous solution containing S 2-, Se 2- and Te 2-, respectively. The nanotube diameter can be controlled from 150 to 400 nm related to the dimension of templates. The XRD patterns show the cadmium chalcogenide nanotubes all corresponding to face-centered cubic structure. © 2012 Elsevier B.V. All rights reserved.

  4. Nanostructured ZnO Films for Room Temperature Ammonia Sensing

    Science.gov (United States)

    Dhivya Ponnusamy; Sridharan Madanagurusamy

    2014-09-01

    Zinc oxide (ZnO) thin films have been deposited by a reactive dc magnetron sputtering technique onto a thoroughly cleaned glass substrate at room temperature. X-ray diffraction revealed that the deposited film was polycrystalline in nature. The field emission scanning electron micrograph (FE-SEM) showed the uniform formation of a rugby ball-shaped ZnO nanostructure. Energy dispersive x-ray analysis (EDX) confirmed that the film was stoichiometric and the direct band gap of the film, determined using UV-Vis spectroscopy, was 3.29 eV. The ZnO nanostructured film exhibited better sensing towards ammonia (NH3) at room temperature (˜30°C). The fabricated ZnO film based sensor was capable of detecting NH3 at as low as 5 ppm, and its parameters, such as response, selectivity, stability, and response/recovery time, were also investigated.

  5. Irreconcilable room temperature magnetotransport properties of polypyrrole nanoparticles and nanorods

    Science.gov (United States)

    Rehman Sagar, Rizwan Ur; Stadler, Florian J.; Navale, Sachin T.; Mane, Rajaram S.; Nazir, Adnan; Nabi, Ghulam

    2017-09-01

    The morphology of nanostructures plays a vital role in determining the conductivity of specimens and, consequently, affects the efficiency of magnetoelectronic devices such as magnetic field sensors. Herein, nanoparticles (NPs) and nanorods (NRs) of conducting polymer polypyrrole have been synthesized at room temperature via the chemical oxidative polymerization method. The positive and negative magnetoresistance signatures are respectively obtained in NPs and NRs morphology, respectively. Both morphologies have conduction in the variable range-hopping regime with the average charge carrier hopping length being highly influenced by the sign of magnetoresistance. This morphology dependence is not only interesting for fundamental research but it also allows for tuning magnetic field sensor materials to be usable at room temperature for the desired characteristics.

  6. Broadband room temperature strong coupling between quantum dots and metamaterials.

    Science.gov (United States)

    Indukuri, Chaitanya; Yadav, Ravindra Kumar; Basu, J K

    2017-08-17

    Herein, we report the first demonstration of room temperature enhanced light-matter coupling in the visible regime for metamaterials using cooperative coupled quasi two dimensional quantum dot assemblies located at precise distances from the hyperbolic metamaterial (HMM) templates. The non-monotonic variation of the magnitude of strong coupling, manifested in terms of strong splitting of the photoluminescence of quantum dots, can be explained in terms of enhanced LDOS near the surface of such metamaterials as well as the plasmon mediated super-radiance of closely spaced quantum dots (QDs). Our methodology of enhancing broadband, room temperature, light-matter coupling in the visible regime for metamaterials opens up new possibilities of utilising these materials for a wide range of applications including QD based thresholdless nanolasers and novel metamaterial based integrated photonic devices.

  7. Single-photon-level quantum memory at room temperature

    CERN Document Server

    Reim, K F; Lee, K C; Nunn, J; Langford, N K; Walmsley, I A

    2010-01-01

    Quantum memories capable of storing single photons are essential building blocks for quantum information processing, enabling the storage and transfer of quantum information over long distances. Devices operating at room temperature can be deployed on a large scale and integrated into existing photonic networks, but so far warm quantum memories have been susceptible to noise at the single photon level. This problem is circumvented in cold atomic ensembles, but these are bulky and technically complex. Here we demonstrate controllable, broadband and efficient storage and retrieval of weak coherent light pulses at the single-photon level in warm atomic caesium vapour using the far off-resonant Raman memory scheme. The unconditional noise floor is found to be low enough to operate the memory in the quantum regime at room temperature.

  8. Ge-on-Si laser operating at room temperature.

    Science.gov (United States)

    Liu, Jifeng; Sun, Xiaochen; Camacho-Aguilera, Rodolfo; Kimerling, Lionel C; Michel, Jurgen

    2010-03-01

    Monolithic lasers on Si are ideal for high-volume and large-scale electronic-photonic integration. Ge is an interesting candidate owing to its pseudodirect gap properties and compatibility with Si complementary metal oxide semiconductor technology. Recently we have demonstrated room-temperature photoluminescence, electroluminescence, and optical gain from the direct gap transition of band-engineered Ge-on-Si using tensile strain and n-type doping. Here we report what we believe to be the first experimental observation of lasing from the direct gap transition of Ge-on-Si at room temperature using an edge-emitting waveguide device. The emission exhibited a gain spectrum of 1590-1610 nm, line narrowing and polarization evolution from a mixed TE/TM to predominantly TE with increasing gain, and a clear threshold behavior.

  9. Observation of Optomechanical Quantum Correlations at Room Temperature

    CERN Document Server

    Purdy, T P; Srinivasan, K; Taylor, J M

    2016-01-01

    By shining laser light through a nanomechanical beam, we measure the beam's thermally driven vibrations and perturb its motion with optical forces at a level dictated by the Heisenberg measurement-disturbance uncertainty relation. Such quantum backaction is typically difficult to observe at room temperature where the motion driven by optical quantum intensity fluctuations is many orders of magnitude smaller than the thermal motion. We demonstrate a cross-correlation technique to distinguish optically driven motion from thermally driven motion, observing this quantum backaction signature up to room temperature. While it is often difficult to absolutely calibrate optical detection, we use the scale of the quantum correlations, which is determined by fundamental constants, to gauge the size of thermal motion, demonstrating a path towards absolute thermometry with quantum mechanically calibrated ticks.

  10. Room Temperature Ultralow Threshold GaN Nanowire Polariton Laser

    KAUST Repository

    Das, Ayan

    2011-08-01

    We report ultralow threshold polariton lasing from a single GaN nanowire strongly coupled to a large-area dielectric microcavity. The threshold carrier density is 3 orders of magnitude lower than that of photon lasing observed in the same device, and 2 orders of magnitude lower than any existing room-temperature polariton devices. Spectral, polarization, and coherence properties of the emission were measured to confirm polariton lasing. © 2011 American Physical Society.

  11. Silicon photodiodes with high photoconductive gain at room temperature.

    Science.gov (United States)

    Li, X; Carey, J E; Sickler, J W; Pralle, M U; Palsule, C; Vineis, C J

    2012-02-27

    Silicon photodiodes with high photoconductive gain are demonstrated. The photodiodes are fabricated in a complementary metal-oxide-semiconductor (CMOS)-compatible process. The typical room temperature responsivity at 940 nm is >20 A/W and the dark current density is ≈ 100 nA/cm2 at 5 V reverse bias, yielding a detectivity of ≈ 10(14) Jones. These photodiodes are good candidates for applications that require high detection sensitivity and low bias operation.

  12. A Na+ Superionic Conductor for Room-Temperature Sodium Batteries

    Science.gov (United States)

    Song, Shufeng; Duong, Hai M.; Korsunsky, Alexander M.; Hu, Ning; Lu, Li

    2016-08-01

    Rechargeable lithium ion batteries have ruled the consumer electronics market for the past 20 years and have great significance in the growing number of electric vehicles and stationary energy storage applications. However, in addition to concerns about electrochemical performance, the limited availability of lithium is gradually becoming an important issue for further continued use and development of lithium ion batteries. Therefore, a significant shift in attention has been taking place towards new types of rechargeable batteries such as sodium-based systems that have low cost. Another important aspect of sodium battery is its potential compatibility with the all-solid-state design where solid electrolyte is used to replace liquid one, leading to simple battery design, long life span, and excellent safety. The key to the success of all-solid-state battery design is the challenge of finding solid electrolytes possessing acceptable high ionic conductivities at room temperature. Herein, we report a novel sodium superionic conductor with NASICON structure, Na3.1Zr1.95Mg0.05Si2PO12 that shows high room-temperature ionic conductivity of 3.5 × 10‑3 S cm‑1. We also report successful fabrication of a room-temperature solid-state Na-S cell using this conductor.

  13. Remote control of magnetostriction-based nanocontacts at room temperature.

    Science.gov (United States)

    Jammalamadaka, S Narayana; Kuntz, Sebastian; Berg, Oliver; Kittler, Wolfram; Kannan, U Mohanan; Chelvane, J Arout; Sürgers, Christoph

    2015-09-01

    The remote control of the electrical conductance through nanosized junctions at room temperature will play an important role in future nano-electromechanical systems and electronic devices. This can be achieved by exploiting the magnetostriction effects of ferromagnetic materials. Here we report on the electrical conductance of magnetic nanocontacts obtained from wires of the giant magnetostrictive compound Tb0.3Dy0.7Fe1.95 as an active element in a mechanically controlled break-junction device. The nanocontacts are reproducibly switched at room temperature between "open" (zero conductance) and "closed" (nonzero conductance) states by variation of a magnetic field applied perpendicularly to the long wire axis. Conductance measurements in a magnetic field oriented parallel to the long wire axis exhibit a different behaviour where the conductance switches between both states only in a limited field range close to the coercive field. Investigating the conductance in the regime of electron tunneling by mechanical or magnetostrictive control of the electrode separation enables an estimation of the magnetostriction. The present results pave the way to utilize the material in devices based on nano-electromechanical systems operating at room temperature.

  14. A Na+ Superionic Conductor for Room-Temperature Sodium Batteries

    Science.gov (United States)

    Song, Shufeng; Duong, Hai M.; Korsunsky, Alexander M.; Hu, Ning; Lu, Li

    2016-01-01

    Rechargeable lithium ion batteries have ruled the consumer electronics market for the past 20 years and have great significance in the growing number of electric vehicles and stationary energy storage applications. However, in addition to concerns about electrochemical performance, the limited availability of lithium is gradually becoming an important issue for further continued use and development of lithium ion batteries. Therefore, a significant shift in attention has been taking place towards new types of rechargeable batteries such as sodium-based systems that have low cost. Another important aspect of sodium battery is its potential compatibility with the all-solid-state design where solid electrolyte is used to replace liquid one, leading to simple battery design, long life span, and excellent safety. The key to the success of all-solid-state battery design is the challenge of finding solid electrolytes possessing acceptable high ionic conductivities at room temperature. Herein, we report a novel sodium superionic conductor with NASICON structure, Na3.1Zr1.95Mg0.05Si2PO12 that shows high room-temperature ionic conductivity of 3.5 × 10−3 S cm−1. We also report successful fabrication of a room-temperature solid-state Na-S cell using this conductor. PMID:27572915

  15. Room-temperature single-electron transistors using alkanedithiols

    Energy Technology Data Exchange (ETDEWEB)

    Luo Kang; Chae, D-H; Yao Zhen [Department of Physics, University of Texas at Austin, Austin, TX 78712 (United States); Center for Nano- and Molecular Science and Technology, University of Texas at Austin, Austin, TX 78712 (United States); Texas Materials Institute, University of Texas at Austin, Austin, TX 78712 (United States)

    2007-11-21

    We have fabricated single-electron transistors by alkanedithiol molecular self-assembly. The devices consist of spontaneously formed ultrasmall Au nanoparticles linked by alkanedithiols to nanometer-spaced Au electrodes created by electromigration. The devices reproducibly exhibit addition energies of a few hundred meV, which enables the observation of single-electron tunneling at room temperature. At low temperatures, tunneling through discrete energy levels in the Au nanoparticles is observed, which is accompanied by the excitations of molecular vibrations at large bias voltage.

  16. Room temperature ferromagnetism in ZnO prepared by microemulsion

    Directory of Open Access Journals (Sweden)

    Qingyu Xu

    2011-09-01

    Full Text Available Clear room temperature ferromagnetism has been observed in ZnO powders prepared by microemulsion. The O vacancy (VO clusters mediated by the VO with one electron (F center contributed to the ferromagnetism, while the isolated F centers contributed to the low temperature paramagnetism. Annealing in H2 incorporated interstitial H (Hi in ZnO, and removed the isolated F centers, leading to the suppression of the paramagnetism. The ferromagnetism has been considered to originate from the VO clusters mediated by the Hi, leading to the enhancement of the coercivity. The ferromagnetism disappeared after annealing in air due to the reduction of Hi.

  17. Room temperature chiral discrimination in paramagnetic NMR spectroscopy

    CERN Document Server

    Soncini, Alessandro

    2016-01-01

    A recently proposed theory of chiral discrimination in NMR spectroscopy based on the detection of a molecular electric polarization $\\mathbf{P}$ rotating in a plane perpendicular to the NMR magnetic field [A. D. Buckingham, J. Chem. Phys. $\\mathbf{140}$, 011103 (2014)], is here generalized to paramagnetic systems. Our theory predicts new contributions to $\\mathbf{P}$, varying as the square of the inverse temperature. Ab initio calculations for ten Dy$^{3+}$ complexes, at 293K, show that in strongly anisotropic paramagnetic molecules $\\mathbf{P}$ can be more than 1000 times larger than in diamagnetic molecules, making paramagnetic NMR chiral discrimination amenable to room temperature detection.

  18. Room Temperature Chemical Oxidation of Delafossite-Type Oxides

    Science.gov (United States)

    Trari, M.; Töpfer, J.; Doumerc, J. P.; Pouchard, M.; Ammar, A.; Hagenmuller, P.

    1994-07-01

    Examination of the delafossite-type structure of CuLaO 2 and CuYO 2 suggests that there is room enough to accomodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu + into Cu 2+. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu 2+ is given by TGA, iodometric titration, and magnetic (static and EPR) measurements. The obtained La and Y compounds seem to behave in a different way: whereas CuLaO 2+ x appears as a single phase, CuYO 2+ x corresponds to a two-phase mixture, with respectively low and high x values, the latter being isostructural with the thermally oxidized compound recently reported by Cava et al. Comparison is stressed between the oxides obtained by oxidation at room and those obtained at higher temperatures.

  19. Unique Room Temperature Light Emitting Diode Based on 2D Hybrid Organic-Inorganic Low Dimensional Perovskite Semiconductor

    CERN Document Server

    Vassilakopoulou, Anastasia; Koutselas, Ioannis

    2016-01-01

    Room temperature single layer light emitting diode(LED), based on a two dimensional hybrid organic-inorganic semiconductor(HOIS), is demonstrated. This simple, low cost excitonic LED operates at low voltages. Such an excitonic device is presented for the first time as functioning at room temperature. The newly introduced class of perovskite LEDs, until now based on 3D perovksite HOIS, is now broadened with the implementation of the 2D HOIS. Novel functionalities can be realized since it is now possible to access the hybrid's 2D semiconductor advantageous properties, such as the increased excitonic peak wavelength tunability, excitonic binding energy and oscillator strength.

  20. High temperature superconducting axial field magnetic coupler: realization and test

    Science.gov (United States)

    Belguerras, L.; Mezani, S.; Lubin, T.; Lévêque, J.; Rezzoug, A.

    2015-09-01

    Contactless torque transmission through a large airgap is required in some industrial applications in which hermetic isolation is necessary. This torque transmission usually uses magnetic couplers, whose dimension strongly depends on the airgap flux density. The use of high temperature superconducting (HTS) coils to create a strong magnetic field may constitute a solution to reduce the size of the coupler. It is also possible to use this coupler to replace a torque tube in transmitting the torque produced by a HTS motor to its load. This paper presents the detailed construction and tests of an axial field HTS magnetic coupler. Pancake coils have been manufactured from BSCCO tape and used in one rotor of the coupler. The second rotor is mainly composed of NdFeB permanent magnets. Several tests have been carried out showing that the constructed coupler is working properly. A 3D finite element (FE) model of the studied coupler has been developed. Airgap magnetic field and torque measurements have been carried out and compared to the FE results. It has been shown that the measured and the computed quantities are in satisfactory agreement.

  1. Scalable quantum register based on coupled electron spins in a room temperature solid

    CERN Document Server

    Neumann, P; Naydenov, B; Beck, J; Rempp, F; Steiner, M; Jacques, V; Balasubramanian, G; Markham, M L; Twitchen, D J; Pezzagna, S; Meijer, J; Twamley, J; Jelezko, F; Wrachtrup, J; 10.1038/nphys1536

    2010-01-01

    Realization of devices based on quantum laws might lead to building processors that outperform their classical analogues and establishing unconditionally secure communication protocols. Solids do usually present a serious challenge to quantum coherence. However, owing to their spin-free lattice and low spin orbit coupling, carbon materials and particularly diamond are suitable for hosting robust solid state quantum registers. We show that scalable quantum logic elements can be realized by exploring long range magnetic dipolar coupling between individually addressable single electron spins associated with separate color centers in diamond. Strong distance dependence of coupling was used to characterize the separation of single qubits 98 A with unprecedented accuracy (3 A) close to a crystal lattice spacing. Our demonstration of coherent control over both electron spins, conditional dynamics, selective readout as well as switchable interaction, opens the way towards a room temperature solid state scalable quant...

  2. Room temperature phosphorescence of metal-free organic materials in amorphous polymer matrices.

    Science.gov (United States)

    Lee, Dongwook; Bolton, Onas; Kim, Byoung Choul; Youk, Ji Ho; Takayama, Shuichi; Kim, Jinsang

    2013-04-24

    Developing metal-free organic phosphorescent materials is promising but challenging because achieving emissive triplet relaxation that outcompetes the vibrational loss of triplets, a key process to achieving phosphorescence, is difficult without heavy metal atoms. While recent studies reveal that bright room temperature phosphorescence can be realized in purely organic crystalline materials through directed halogen bonding, these organic phosphors still have limitations to practical applications due to the stringent requirement of high quality crystal formation. Here we report bright room temperature phosphorescence by embedding a purely organic phosphor into an amorphous glassy polymer matrix. Our study implies that the reduced beta (β)-relaxation of isotactic PMMA most efficiently suppresses vibrational triplet decay and allows the embedded organic phosphors to achieve a bright 7.5% phosphorescence quantum yield. We also demonstrate a microfluidic device integrated with a novel temperature sensor based on the metal-free purely organic phosphors in the temperature-sensitive polymer matrix. This unique system has many advantages: (i) simple device structures without feeding additional temperature sensing agents, (ii) bright phosphorescence emission, (iii) a reversible thermal response, and (iv) tunable temperature sensing ranges by using different polymers.

  3. Terahertz pulsed photogenerated current in microdiodes at room temperature

    CERN Document Server

    Ilkov, Marjan; Manolescu, Andrei; Valfells, Agust

    2015-01-01

    Space-charge induced modulation of the diode current under photoemission leads to the formation of beamlets with time delay between formation corresponding to THz frequency. We investigate the effect of electron temperature and internal space-charge forces on the formation and persistence of the beamlets. We find that for low applied electric fields (less than 8MV/m) temperature effects are most important in causing beam degradation, whereas at higher fields intra-beamlet space-charge forces are dominant. The current modulation is most robust when there is only one beamlet present in the diode gap at a time, corresponding to a macroscopic version of the Coulomb blockade. It is shown that a vacuum microdiode can operate quite well as a tunable THz oscillator at room temperature with an applied electric field above 10 MV/m and diode gap on the order of 100 nanometers.

  4. Terahertz pulsed photogenerated current in microdiodes at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ilkov, Marjan; Torfason, Kristinn; Manolescu, Andrei, E-mail: manoles@ru.is; Valfells, Ágúst [School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik (Iceland)

    2015-11-16

    Space-charge modulation of the current in a vacuum diode under photoemission leads to the formation of beamlets with time periodicity corresponding to THz frequencies. We investigate the effect of the emitter temperature and internal space-charge forces on the formation and persistence of the beamlets. We find that temperature effects are most important for beam degradation at low values of the applied electric field, whereas at higher fields, intra-beamlet space-charge forces are dominant. The current modulation is most robust when there is only one beamlet present in the diode gap at a time, corresponding to a macroscopic version of the Coulomb blockade. It is shown that a vacuum microdiode can operate quite well as a tunable THz oscillator at room temperature with an applied electric field above 10 MV/m and a diode gap of the order of 100 nm.

  5. Conformation of protonated glutamic acid at room and cryogenic temperatures.

    Science.gov (United States)

    Bouchet, Aude; Klyne, Johanna; Ishiuchi, Shun-Ichi; Fujii, Masaaki; Dopfer, Otto

    2017-05-03

    Recognition properties of biologically relevant molecules depend on their conformation. Herein, the conformation of protonated glutamic acid (H(+)Glu) isolated in quadruple ion traps is characterized by vibrational spectroscopy at room and cryogenic temperatures and dispersion-corrected density functional theory calculations at the B3LYP-D3/aug-cc-pVTZ level. The infrared multiple photon dissociation (IRMPD) spectrum recorded in the fingerprint range at room temperature using an IR free electron laser is attributed to the two most stable and nearly isoenergetic conformations (1-cc and 2-cc) with roughly equal population (ΔG298 = 0.0 kJ mol(-1)). Both have bridging C[double bond, length as m-dash]O(HNH)(+)O[double bond, length as m-dash]C ionic H-bonds of rather different strengths but cannot be distinguished by their similar IRMPD spectra. In contrast, the higher-resolution single-photon IRPD spectrum of H2-tagged H(+)Glu recorded in the conformation-sensitive X-H stretch range in a trap held at 10 K distinguishes both conformers. At low temperature, 1-cc is roughly twice more abundant than 2-cc, in line with its slightly lower calculated energy (ΔE0 = 0.5 kJ mol(-1)). This example illustrates the importance of cryogenic cooling, single-photon absorption conditions, and the consideration of the X-H stretch range for the identification of biomolecular conformations involving hydrogen bonds.

  6. Xenon Recovery at Room Temperature using Metal-Organic Frameworks.

    Science.gov (United States)

    Elsaidi, Sameh K; Ongari, Daniele; Xu, Wenqian; Mohamed, Mona H; Haranczyk, Maciej; Thallapally, Praveen K

    2017-08-10

    Xenon is known to be a very efficient anesthetic gas, but its cost prohibits the wider use in medical industry and other potential applications. It has been shown that Xe recovery and recycling from anesthetic gas mixtures can significantly reduce its cost as anesthetic. The current technology uses series of adsorbent columns followed by low-temperature distillation to recover Xe; this method is expensive to use in medical facilities. Herein, we propose a much simpler and more efficient system to recover and recycle Xe from exhaled anesthetic gas mixtures at room temperature using metal-organic frameworks (MOFs). Among the MOFs tested, PCN-12 exhibits unprecedented performance with high Xe capacity and Xe/O2 , Xe/N2 and Xe/CO2 selectivity at room temperature. The in situ synchrotron measurements suggest that Xe is occupies the small pockets of PCN-12 compared to unsaturated metal centers (UMCs). Computational modeling of adsorption further supports our experimental observation of Xe binding sites in PCN-12. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Spin-valley caloritronics in silicene near room temperature

    Science.gov (United States)

    Zhai, Xuechao; Gao, Wenwen; Cai, Xinlong; Fan, Ding; Yang, Zhihong; Meng, Lan

    2016-12-01

    Two-dimensional silicene, with an observable intrinsic spin-orbit coupling, has a great potential to perform fascinating physics and new types of applications in spintronics and valleytronics. By introducing an electromotive force from a temperature difference in ferromagnetic silicene, we discover that a longitudinal spin Seebeck effect can be driven even near room temperature, with spin-up and spin-down currents flowing in opposite directions, originating from the asymmetric electron-hole spin band structures. We further propose a silicene field-effect transistor constructed of two ferromagnetic electrodes and a central dual-gated region, and find that a valley Seebeck effect appears, with currents from two different valleys flowing in opposite directions. The forbidden transport channels are determined by either spin-valley dependent band gaps or spin mismatch. By tuning the electric field in the central region, the transport gaps depending on spin and valley vary correspondingly, and a transition from valley Seebeck effect to spin Seebeck effect is observed. These spin-valley caloritronic results near room temperature are robust against many real perturbations, and thus suggest silicene to be an excellent candidate for future energy-saving technologies and bidirectional information processing in solid-state circuits.

  8. On the fluorescence of C60 at room temperature

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The fluorescence properties of C 60 in different organic solvents have been investigated at room temperature. Three fluorescence emission centers are discovered and ascribed to different aggregations of C 60 in solvent. A series of blue fluorescence peaks centered at 440 nm derive from C 60 nanoparticles; a distinctive yellow-green fluorescence band in 575 nm region arises from the aggregates of C 60 nanoparticles; a more informative salmon fluorescence band around 700 nm originates from C 60 microcrystals. And the distinct configurations of C 60 aggregations are closely associated with the characteristic interaction between C 60 and solvent molecules.

  9. Room-Temperature Dephasing in InAs Quantum Dots

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang; Mørk, Jesper;

    2000-01-01

    The room temperature dephasing in InAs/InGaAs/GaAs self-assembled quantum dots, embedded in a waveguide for laser applications, is measured using two independent methods: spectral hole burning and four-wave mixing. Without the application of bias current for electrical carrier injection......, a dephasing time of ~260 fs, weakly dependent on the optical excitation density, is found and attributed to phonon interaction. The application of bias current, leading to population inversion in the dot ground state and optical gain, strongly decreases the dephasing time to less than 50 fs, likely due...

  10. Recommended reference materials for realization of physicochemical properties pressure-volume-temperature relationships

    CERN Document Server

    Herington, E F G

    1977-01-01

    Recommended Reference Materials for Realization of Physicochemical Properties presents recommendations of reference materials for use in measurements involving physicochemical properties, namely, vapor pressure; liquid-vapor critical temperature and critical pressure; orthobaric volumes of liquid and vapor; pressure-volume-temperature properties of the unsaturated vapor or gas; and pressure-volume-temperature properties of the compressed liquid. This monograph focuses on reference materials for vapor pressures at temperatures up to 770 K, as well as critical temperatures and critical pressures

  11. Room-temperature amorphous alloy field-effect transistor exhibiting particle and wave electronic transport

    Energy Technology Data Exchange (ETDEWEB)

    Fukuhara, M., E-mail: fukuhara@niche.tohoku.ac.jp [New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan); Kawarada, H. [Research and Development Center, Waseda University, Tokyo 162-0041 (Japan)

    2015-02-28

    The realization of room-temperature macroscopic field effect transistors (FETs) will lead to new epoch-making possibilities for electronic applications. The I{sub d}-V{sub g} characteristics of the millimeter-sized aluminum-oxide amorphous alloy (Ni{sub 0.36}Nb{sub 0.24}Zr{sub 0.40}){sub 90}H{sub 10} FETs were measured at a gate-drain bias voltage of 0–60 μV in nonmagnetic conditions and under a magnetic fields at room temperature. Application of dc voltages to the gate electrode resulted in the transistor exhibiting one-electron Coulomb oscillation with a period of 0.28 mV, Fabry-Perot interference with a period of 2.35 μV under nonmagnetic conditions, and a Fano effect with a period of 0.26 mV for Vg and 0.2 T under a magnetic field. The realization of a low-energy controllable device made from millimeter-sized Ni-Nb-Zr-H amorphous alloy throws new light on cluster electronics.

  12. Prediction of near-room-temperature quantum anomalous Hall effect on honeycomb materials.

    Science.gov (United States)

    Wu, Shu-Chun; Shan, Guangcun; Yan, Binghai

    2014-12-19

    Recently, the long-sough quantum anomalous Hall effect was realized in a magnetic topological insulator. However, the requirement of an extremely low temperature (approximately 30 mK) hinders realistic applications. Based on ab initio band structure calculations, we propose a quantum anomalous Hall platform with a large energy gap of 0.34 and 0.06 eV on honeycomb lattices comprised of Sn and Ge, respectively. The ferromagnetic (FM) order forms in one sublattice of the honeycomb structure by controlling the surface functionalization rather than dilute magnetic doping, which is expected to be visualized by spin polarized STM in experiment. Strong coupling between the inherent quantum spin Hall state and ferromagnetism results in considerable exchange splitting and, consequently, an FM insulator with a large energy gap. The estimated mean-field Curie temperature is 243 and 509 K for Sn and Ge lattices, respectively. The large energy gap and high Curie temperature indicate the feasibility of the quantum anomalous Hall effect in the near-room-temperature and even room-temperature regions.

  13. A Computed Room Temperature Line List for Phosphine

    CERN Document Server

    Sousa-Silva, Clara; Tennyson, Jonathan

    2013-01-01

    An accurate and comprehensive room temperature rotation-vibration transition line list for phosphine (31PH3) is computed using a newly refined potential energy surface and a previously constructed ab initio electric dipole moment surface. Energy levels, Einstein A coefficients and transition intensities are computed using these surfaces and a variational approach to the nuclear motion problem as implemented in the program TROVE. A ro-vibrational spectrum is computed, covering the wavenumber range 0 to 8000 cm-1. The resulting line list, which is appropriate for temperatures up to 300 K, consists of a total of 137 million transitions between 5.6 million energy levels. Several of the band centres are shifted to better match experimental transition frequencies. The line list is compared to the most recent HITRAN database and other laboratorial sources. Transition wavelengths and intensities are generally found to be in good agreement with the existing experimental data, with particularly close agreement for the ...

  14. Room temperature ferroelectricity in continuous croconic acid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xuanyuan; Lu, Haidong; Yin, Yuewei; Ahmadi, Zahra; Costa, Paulo S. [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Zhang, Xiaozhe [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Department of Physics, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Xiao; Yu, Le; Cheng, Xuemei [Department of Physics, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010 (United States); DiChiara, Anthony D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Gruverman, Alexei, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu; Enders, Axel, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu; Xu, Xiaoshan, E-mail: alexei-gruverman@unl.edu, E-mail: a.enders@me.com, E-mail: xiaoshan.xu@unl.edu [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States)

    2016-09-05

    Ferroelectricity at room temperature has been demonstrated in nanometer-thin quasi 2D croconic acid thin films, by the polarization hysteresis loop measurements in macroscopic capacitor geometry, along with observation and manipulation of the nanoscale domain structure by piezoresponse force microscopy. The fabrication of continuous thin films of the hydrogen-bonded croconic acid was achieved by the suppression of the thermal decomposition using low evaporation temperatures in high vacuum, combined with growth conditions far from thermal equilibrium. For nominal coverages ≥20 nm, quasi 2D and polycrystalline films, with an average grain size of 50–100 nm and 3.5 nm roughness, can be obtained. Spontaneous ferroelectric domain structures of the thin films have been observed and appear to correlate with the grain patterns. The application of this solvent-free growth protocol may be a key to the development of flexible organic ferroelectric thin films for electronic applications.

  15. Thermal investigations of a room temperature magnetic refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Smaili, Arezki; Chiba, Younes [Ecole Nationale Polytechnique d' Alger (Algeria)], email: arezki.smaili@enp.edu.dz

    2011-07-01

    Magnetic refrigeration is a concept based on the magnetocaloric effect that some materials exhibit when the external magnetic field changes. The aim of this paper is to assess the performance of a numerical model in predicting parameters of an active magnetic regenerator refrigerator. Numerical simulations were conducted to perform a thermal analysis on an active magnetic regenerator refrigerator operating near room temperature with and without applied cooling load. Curves of temperature span, cooling capacity and thermal efficiency as functions of the operating conditions were drawn and are presented in this paper. Results showed that at fixed frequency Ql versus mf has an optimum and COP was increased with cycle frequency values. This study demonstrated that the proposed numerical model could be used to predict parameters of an active magnetic regenerator refrigerator as it provides consistent results.

  16. Room temperature coherent control of coupled single spins in solid

    CERN Document Server

    Gaebel, T; Popa, I; Wittmann, C; Neumann, P; Jelezko, F; Rabeau, J R; Stavrias, N; Greentree, A D; Prawer, S; Meijer, J; Twamley, J; Hemmer, P R; Wrachtrup, J

    2006-01-01

    Coherent coupling between single quantum objects is at the heart of modern quantum physics. When coupling is strong enough to prevail over decoherence, it can be used for the engineering of correlated quantum states. Especially for solid-state systems, control of quantum correlations has attracted widespread attention because of applications in quantum computing. Such coherent coupling has been demonstrated in a variety of systems at low temperature1, 2. Of all quantum systems, spins are potentially the most important, because they offer very long phase memories, sometimes even at room temperature. Although precise control of spins is well established in conventional magnetic resonance3, 4, existing techniques usually do not allow the readout of single spins because of limited sensitivity. In this paper, we explore dipolar magnetic coupling between two single defects in diamond (nitrogen-vacancy and nitrogen) using optical readout of the single nitrogen-vacancy spin states. Long phase memory combined with a d...

  17. Room temperature skyrmion ground state stabilized through interlayer exchange coupling

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gong, E-mail: gchenncem@gmail.com; Schmid, Andreas K. [NCEM, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Mascaraque, Arantzazu [Depto. Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Unidad Asociada IQFR (CSIC) - UCM, 28040 Madrid (Spain); N' Diaye, Alpha T. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-06-15

    Possible magnetic skyrmion device applications motivate the search for structures that extend the stability of skyrmion spin textures to ambient temperature. Here, we demonstrate an experimental approach to stabilize a room temperature skyrmion ground state in chiral magnetic films via exchange coupling across non-magnetic spacer layers. Using spin polarized low-energy electron microscopy to measure all three Cartesian components of the magnetization vector, we image the spin textures in Fe/Ni films. We show how tuning the thickness of a copper spacer layer between chiral Fe/Ni films and perpendicularly magnetized Ni layers permits stabilization of a chiral stripe phase, a skyrmion phase, and a single domain phase. This strategy to stabilize skyrmion ground states can be extended to other magnetic thin film systems and may be useful for designing skyrmion based spintronics devices.

  18. Radiation stability of some room temperature ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Jagadeeswara Rao, Ch.; Venkatesan, K.A. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil nadu (India); Tata, B.V.R. [Condensed Matter Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil nadu (India); Nagarajan, K., E-mail: knag@igcar.gov.i [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil nadu (India); Srinivasan, T.G.; Vasudeva Rao, P.R. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil nadu (India)

    2011-05-15

    Radiation stability of some room temperature ionic liquids (RTILs) that find useful electrochemical applications in nuclear fuel cycle has been evaluated. The ionic liquids such as protonated betaine bis(trifluoromethylsulfonyl)imide (HbetNTf{sub 2}), aliquat 336 (tri-n-octlymethylammonium chloride), 1-butyl-3-methylimidazolium chloride (bmimCl), 1-hexyl-3-methylimidazolium chloride (hmimCl), N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyNTf{sub 2}) and N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf{sub 2}) have been irradiated to various absorbed dose levels, up to 700 kGy. The effect of gamma radiation on these ionic liquids has been evaluated by determining the variations in the physical properties such as color, density, viscosity, refractive index and electrochemical window. The changes in density, viscosity and refractive index of these ionic liquids upon irradiation were insignificant; however, the color and electrochemical window varied significantly with increase of absorbed dose. -- Research highlights: {yields} Room temperature ionic liquids (RTILs). {yields} Gamma irradiation. {yields} Determination of physical and electrochemical properties. {yields} Minimal change in physical properties. {yields} Large variation in electrochemical window.

  19. Identifying multiexcitons in Mo S2 monolayers at room temperature

    Science.gov (United States)

    Lee, Hyun Seok; Kim, Min Su; Kim, Hyun; Lee, Young Hee

    2016-04-01

    One of the unique features of atomically thin two-dimensional materials is strong Coulomb interactions due to the reduced dielectric screening effect; this feature enables the study of many-body phenomena such as excitons, trions, and biexcitons. However, identification of biexcitons remains unresolved owing to their broad peak feature at room temperature. Here, we investigate multiexcitons in monolayer Mo S2 using both electrical and optical doping and identify the transition energies for each exciton. The binding energy of the assigned biexciton is twice that of the trion, in quantitative agreement with theoretical predictions. The biexciton population is predominant under optical doping but negligible under electrical doping. The biexciton population is quadratically proportional to the exciton population, obeying the mass-action theory. Our results illustrate the stable formation of not only trions but also biexcitons due to strong Coulomb interaction even at room temperature; therefore, these results provide a deeper understanding of the complex excitonic behaviors in two-dimensional semiconductors.

  20. Simple room temperature bonding of thermoplastics and poly(dimethylsiloxane).

    Science.gov (United States)

    Sunkara, Vijaya; Park, Dong-Kyu; Hwang, Hyundoo; Chantiwas, Rattikan; Soper, Steven A; Cho, Yoon-Kyoung

    2011-03-01

    We describe a simple and versatile method for bonding thermoplastics to elastomeric polydimethylsiloxane (PDMS) at room temperature. The bonding of various thermoplastics including polycarbonate (PC), cyclic olefin copolymer (COC), polymethylmethacrylate (PMMA), and polystyrene (PS), to PDMS has been demonstrated at room temperature. An irreversible bonding was formed instantaneously when the thermoplastics, activated by oxygen plasma followed by aminopropyltriethoxysilane modification, were brought into contact with the plasma treated PDMS. The surface modified thermoplastics were characterized by water contact angle measurements and X-ray photoelectron spectroscopy. The tensile strength of the bonded hybrid devices fabricated with PC, COC, PMMA, and PS was found to be 430, 432, 385, and 388 kPa, respectively. The assembled devices showed high burst resistance at a maximum channel pressure achievable by an in-house built syringe pump, 528 kPa. Furthermore, they displayed very high hydrolytic stability; no significant change was observed even after the storage in water at 37 °C over a period of three weeks. In addition, this thermoplastic-to-PDMS bonding technique has been successfully employed to fabricate a relatively large sized device. For example, a lab-on-a-disc with a diameter of 12 cm showed no leakage when it spins for centrifugal fluidic pumping at a very high rotating speed of 6000 rpm.

  1. Synthesis of manganese spinel nanoparticles at room temperature by coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.fr [GREMAN, UMR 7347 CNRS-CEA, Universite Francois Rabelais, 15 rue de la chocolaterie, 41000 BLOIS (France); Autret-Lambert, C.; Mathieu, C.; Chartier, T.; Delorme, F. [GREMAN, UMR 7347 CNRS-CEA, Universite Francois Rabelais, 15 rue de la chocolaterie, 41000 BLOIS (France); Seron, A [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 ORLEANS Cedex 2 (France)

    2012-08-15

    This paper is focused on a new route to synthesize Mn{sub 3}O{sub 4} nanoparticles by alkalisation by sodium hydroxide on a manganeous solution at room temperature. The precipitates obtained at different pH values have been characterized by XRD and TEM. Since the first addition of sodium hydroxide, a white Mn(OH){sub 2} precipitate appears. At pH=7, {gamma}-MnOOH phase is predominant with needle like shaped particles. At pH=10, hausmanite nanoparticles, which exhibits well defined cubic shape in the range 50-120 nm are obtained. This new precipitation route is a fast and easy environmentally friendly process to obtain well crystallized hausmanite nanoparticles. - Graphical abstract: TEM image showing Mn{sub 3}O{sub 4} particles after a precipitation at pH=10. Highlights: Black-Right-Pointing-Pointer A new route to synthesize Mn{sub 3}O{sub 4} nanoparticles has been demonstrated. Black-Right-Pointing-Pointer Synthesis has been performed by precipitation at room temperature. Black-Right-Pointing-Pointer The size of the Mn{sub 3}O{sub 4} nanoparticles is between 50 and 120 nm.

  2. Experiments on room temperature optical fiber-fiber direct bonding

    Science.gov (United States)

    Hao, Jinping; Yan, Ping; Xiao, Qirong; Wang, Yaping; Gong, Mali

    2012-08-01

    High quality permanent connection between optical fibers is a significant issue in optics and communication. Studies on room temperature optical large diameter fiber-fiber direct bonding, which is essentially surface interactions of glass material, are presented here. Bonded fiber pairs are obtained for the first time through the bonding technics illustrated here. Two different kinds of bonding technics are provided-fresh surface (freshly grinded and polished) bonding and hydrophobic surface (activated by H2SO4 and HF) bonding. By means of fresh surface bonding, a bonded fiber pair with light transmitting efficiency of 98.1% and bond strength of 21.2 N is obtained. Besides, in the bonding process, chemical surface treatment of fibers' end surfaces is an important step. Therefore, various ways of surface treatment are analyzed and compared, based on atomic force microscopy force curves of differently disposed surfaces. According to the comparison, fresh surfaces are suggested as the prior choice in room temperature optical fiber-fiber bonding, owing to their larger adhesive force, attractive force, attractive distance, and adhesive range.

  3. Exfoliated black phosphorus gas sensing properties at room temperature

    Science.gov (United States)

    Donarelli, M.; Ottaviano, L.; Giancaterini, L.; Fioravanti, G.; Perrozzi, F.; Cantalini, C.

    2016-06-01

    Room temperature gas sensing properties of chemically exfoliated black phosphorus (BP) to oxidizing (NO2, CO2) and reducing (NH3, H2, CO) gases in a dry air carrier have been reported. To study the gas sensing properties of BP, chemically exfoliated BP flakes have been drop casted on Si3N4 substrates provided with Pt comb-type interdigitated electrodes in N2 atmosphere. Scanning electron microscopy and x-ray photoelectron spectroscopy characterizations show respectively the occurrence of a mixed structure, composed of BP coarse aggregates dispersed on BP exfoliated few layer flakes bridging the electrodes, and a clear 2p doublet belonging to BP, which excludes the occurrence of surface oxidation. Room temperature electrical tests in dry air show a p-type response of multilayer BP with measured detection limits of 20 ppb and 10 ppm to NO2 and NH3 respectively. No response to CO and CO2 has been detected, while a slight but steady sensitivity to H2 has been recorded. The reported results confirm, on an experimental basis, what was previously theoretically predicted, demonstrating the promising sensing properties of exfoliated BP.

  4. Room temperature mid-IR single photon spectral imaging

    CERN Document Server

    Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter

    2012-01-01

    Spectral imaging and detection of mid-infrared (mid-IR) wavelengths are emerging as an enabling technology of great technical and scientific interest; primarily because important chemical compounds display unique and strong mid-IR spectral fingerprints revealing valuable chemical information. While modern Quantum cascade lasers have evolved as ideal coherent mid-IR excitation sources, simple, low noise, room temperature detectors and imaging systems still lag behind. We address this need presenting a novel, field-deployable, upconversion system for sensitive, 2-D, mid-IR spectral imaging. Measured room temperature dark noise is 0.2 photons/spatial element/second, which is a billion times below the dark noise level of cryogenically cooled InSb cameras. Single photon imaging and up to 200 x 100 spatial elements resolution is obtained reaching record high continuous wave quantum efficiency of about 20 % for polarized incoherent light at 3 \\mum. The proposed method is relevant for existing and new mid-IR applicat...

  5. Realizing Zinc Blende GaAs/A1GaAs Axial and Radial Heterostructure Nanowires by Tuning the Growth Temperature

    Institute of Scientific and Technical Information of China (English)

    Jingwei Guo; Hui Huang; Xiaomin Ren; Xin Yan; Shiwei Cai; Wei Wang; Yongqing Huang; Qi Wang; Xia Zhang

    2011-01-01

    Vertical zinc blende GaAs/AlGaAs heterostructure nanowires were grown at different temperatures by metalorganic chemical vapor deposition via Au-assisted vapor-liquid-solid mechanism. It was found that radial growth can be enhanced by increasing the growth temperature. The growth of radial heterostructure can be realized at temperature higher than 500℃, while the growth temperature of axial heterostructure is lower than 440℃. The room temperature photoluminescence properties of the nanowires were investigated and the relevant growth mechanism was discussed.

  6. Room temperature coherent spin alignment of silicon vacancies in 4H- and 6H-SiC.

    Science.gov (United States)

    Soltamov, Victor A; Soltamova, Alexandra A; Baranov, Pavel G; Proskuryakov, Ivan I

    2012-06-01

    We report the realization of the optically induced inverse population of the ground-state spin sublevels of the silicon vacancies (V(Si)) in silicon carbide (SiC) at room temperature. The data show that the probed silicon vacancy spin ensemble can be prepared in a coherent superposition of the spin states. Rabi nutations persist for more than 80 μs. Two opposite schemes of the optical alignment of the populations between the ground-state spin sublevels of the silicon vacancy upon illumination with unpolarized light are realized in 4H- and 6H-SiC at room temperature. These altogether make the silicon vacancy in SiC a very favorable defect for spintronics, quantum information processing, and magnetometry.

  7. Advances in materials for room temperature hydrogen sensors.

    Science.gov (United States)

    Arya, Sunil K; Krishnan, Subramanian; Silva, Hayde; Jean, Sheila; Bhansali, Shekhar

    2012-06-21

    Hydrogen (H(2)), as a source of energy, continues to be a compelling choice in applications ranging from fuel cells and propulsion systems to feedstock for chemical, metallurgical and other industrial processes. H(2), being a clean, reliable, and affordable source, is finding ever increasing use in distributed electric power generation and H(2) fuelled cars. Although still under 0.1%, the distributed use of H(2) is the fastest growing area. In distributed H(2) storage, distribution, and consumption, safety continues to be a critical aspect. Affordable safety systems for distributed H(2) applications are critical for the H(2) economy to take hold. Advances in H(2) sensors are driven by specificity, reliability, repeatability, stability, cost, size, response time, recovery time, operating temperature, humidity range, and power consumption. Ambient temperature sensors for H(2) detection are increasingly being explored as they offer specificity, stability and robustness of high temperature sensors with lower operational costs and significantly longer operational lifetimes. This review summarizes and highlights recent developments in room temperature H(2) sensors.

  8. Searching Room Temperature Ferromagnetism in Wide Gap Semiconductors Fe-doped Strontium Titanate and Zinc Oxide

    CERN Document Server

    Pereira, LMC; Wahl, U

    Scientific findings in the very beginning of the millennium are taking us a step further in the new paradigm of technology: spintronics. Upgrading charge-based electronics with the additional degree of freedom of the carriers spin-state, spintronics opens a path to the birth of a new generation of devices with the potential advantages of non-volatility and higher processing speed, integration densities and power efficiency. A decisive step towards this new age lies on the attribution of magnetic properties to semiconductors, the building block of today's electronics, that is, the realization of ferromagnetic semiconductors (FS) with critical temperatures above room temperature. Unfruitful search for intrinsic RT FS lead to the concept of Dilute(d) Magnetic Semiconductors (DMS): ordinary semiconductor materials where 3 d transition metals randomly substitute a few percent of the matrix cations and, by some long-range mechanism, order ferromagnetically. The times are of intense research activity and the last fe...

  9. Room temperature chemical oxidation of delafossite-type oxides

    Energy Technology Data Exchange (ETDEWEB)

    Trari, M.; Toepfer, J.; Doumerc, J.P.; Pouchard, M.; Hagenmuller, P. (Laboratoire de Chimie du Solide du CNRS, Talence (France)); Ammar, A. (Universite Cadi Ayyad, Marrakech (Morocco))

    1994-07-01

    Examination of the delafossite-type structure of CuLaO[sub 2] and CuYO[sub 2] suggests that there is room enough to accommodate intercalated oxide ions and the charge compensation resulting simply from the oxidation of an equivalent amount of Cu[sup +] into Cu[sup 2+]. Reaction with hypohalites in an aqueous solution leads to color change. Evidence of the formation of Cu[sup 2+] is given by TGA, iodometric titration, and magnetic (static and EPR) measurements. The obtained La and Y compounds seem to behave in a different way: Whereas CuLaO[sub 2+x] appears as a single phase, CuYO[sub 2+x] corresponds to a two-phase mixture, with respectively low and high x values, the latter being isostructural with the thermally oxidized compound recently reported. Comparison is stressed between the oxides obtained at higher temperatures.

  10. Room-temperature ferromagnetism in cerium dioxide powders

    Energy Technology Data Exchange (ETDEWEB)

    Rakhmatullin, R. M., E-mail: rrakhmat@kpfu.ru; Pavlov, V. V.; Semashko, V. V.; Korableva, S. L. [Kazan Federal University, Institute of Physics (Russian Federation)

    2015-08-15

    Room-temperature ferromagnetism is detected in a CeO{sub 2} powder with a grain size of about 35 nm and a low (<0.1 at %) manganese and iron content. The ferromagnetism in a CeO{sub 2} sample with a submicron crystallite size and the same manganese and iron impurity content is lower than in the nanocrystalline sample by an order of magnitude. Apart from ferromagnetism, both samples exhibit EPR spectra of localized paramagnetic centers, the concentration of which is lower than 0.01 at %. A comparative analysis of these results shows that the F-center exchange (FCE) mechanism cannot cause ferromagnetism. This conclusion agrees with the charge-transfer ferromagnetism model proposed recently.

  11. Room-temperature LINAC structures for the spallation neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Billen, J. H. (James H.); Young, L. M. (Lloyd M.); Kurennoy, S. (Sergey); Crandall, K. R. (Kenneth R.)

    2001-04-01

    Los Alamos National Laboratory is building room-temperature rf accelerating structures for the Spallation Neutron Source (SNS). These structures, for H{sup -} ions, consist of six 402.5-MHz, 2-MW drift-tube linac (DTL) tanks from 2.5 to 87 MeV followed by four 805-MHz, 4-MW coupled-cavity linac (CCL) modules to 186 MeV. The DTL uses permanent magnet quadrupoles inside the drift tubes arranged in a 6{beta}{lambda} FFODDO lattice with every third drift tube available for diagnostics and steering. The CCL uses a 13{beta}{lambda} FODO electromagnetic quadrupole lattice. Diagnostics and magnets occupy the 2.5{beta}{lambda} spaces between 8-cavity segments. This paper discusses design of the rf cavities and low-power modeling work.

  12. Dynamical Decoupling of a single electron spin at room temperature

    CERN Document Server

    Naydenov, Boris; Hall, Liam T; Shin, Chang; Fedder, Helmut; Hollenberg, Lloyd C L; Jelezko, Fedor; Wrachtrup, Jörg

    2010-01-01

    Here we report the increase of the coherence time T$_2$ of a single electron spin at room temperature by using dynamical decoupling. We show that the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence can prolong the T$_2$ of a single Nitrogen-Vacancy center in diamond up to 2.44 ms compared to the Hahn echo measurement where T$_2 = 390~\\mu$s. Moreover, by performing spin locking experiments we demonstrate that with CPMG the maximum possible $T_2$ is reached. On the other hand, we do not observe strong increase of the coherence time in nanodiamonds, possibly due to the short spin lattice relaxation time $T_1=100~\\mu$s (compared to T$_1$ = 5.93 ms in bulk). An application for detecting low magnetic field is demonstrated, where we show that the sensitivity using the CPMG method is improved by about a factor of two compared to the Hahn echo method.

  13. Single-atom reversible recording at room temperature

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Lin, Rong

    2001-01-01

    A single hydrogen atom can be reversibly switched between two symmetric sites on a silicon dimer at the surface of Si(100) using a scanning tunnelling microscope (STM). This is a model binary switch for silicon-based atom-scale reversible data storage at room temperature. In this paper we...... investigate two important aspects of using this single-atom switch as a memory device. First, the switching is electron stimulated, and through detailed modelling the switching probability per electron is accurately deduced. Second, we have investigated the possibilities for desorbing single hydrogen atoms...... to construct ordered arrays of switches to manufacture a memory device. Two desorption mechanisms have been considered: the well known electron-induced desorption at negative sample bias and a novel mechanism probably involving elastic deformation of the tip. For both mechanisms mechanical stability of the STM...

  14. Ratcheting fatigue behavior of Zircaloy-2 at room temperature

    Science.gov (United States)

    Rajpurohit, R. S.; Sudhakar Rao, G.; Chattopadhyay, K.; Santhi Srinivas, N. C.; Singh, Vakil

    2016-08-01

    Nuclear core components of zirconium alloys experience asymmetric stress or strain cycling during service which leads to plastic strain accumulation and drastic reduction in fatigue life as well as dimensional instability of the component. Variables like loading rate, mean stress, and stress amplitude affect the influence of asymmetric loading. In the present investigation asymmetric stress controlled fatigue tests were conducted with mean stress from 80 to 150 MPa, stress amplitude from 270 to 340 MPa and stress rate from 30 to 750 MPa/s to study the process of plastic strain accumulation and its effect on fatigue life of Zircaloy-2 at room temperature. It was observed that with increase in mean stress and stress amplitude accumulation of ratcheting strain was increased and fatigue life was reduced. However, increase in stress rate led to improvement in fatigue life due to less accumulation of ratcheting strain.

  15. Gas sensing properties of nanocrystalline diamond at room temperature

    Directory of Open Access Journals (Sweden)

    Marina Davydova

    2014-12-01

    Full Text Available This study describes an integrated NH3 sensor based on a hydrogenated nanocrystalline diamond (NCD-sensitive layer coated on an interdigitated electrode structure. The gas sensing properties of the sensor structure were examined using a reducing gas (NH3 at room temperature and were found to be dependent on the electrode arrangement. A pronounced response of the sensor, which was comprised of dense electrode arrays (of 50 µm separation distance, was observed. The sensor functionality was explained by the surface transfer doping effect. Moreover, the three-dimensional model of the current density distribution of the hydrogenated NCD describes the transient flow of electrons between interdigitated electrodes and the hydrogenated NCD surface, that is, the formation of a closed current loop.

  16. Single mode quadrature entangled light from room temperature atomic vapour

    CERN Document Server

    Wasilewski, W; Jensen, K; Madsen, L S; Krauter, H; Polzik, E S

    2009-01-01

    We analyse a novel squeezing and entangling mechanism which is due to correlated Stokes and anti-Stokes photon forward scattering in a multi-level atom vapour. Following the proposal we present an experimental demonstration of 3.5 dB pulsed frequency nondegenerate squeezed (quadrature entangled) state of light using room temperature caesium vapour. The source is very robust and requires only a few milliwatts of laser power. The squeezed state is generated in the same spatial mode as the local oscillator and in a single temporal mode. The two entangled modes are separated by twice the Zeeman frequency of the vapour which can be widely tuned. The narrow-band squeezed light generated near an atomic resonance can be directly used for atom-based quantum information protocols. Its single temporal mode characteristics make it a promising resource for quantum information processing.

  17. Room-temperature semiconductor coherent Smith-Purcell terahertz sources

    Science.gov (United States)

    Smith, Don D.; Belyanin, Alexey

    2011-02-01

    We propose a room-temperature semiconductor source of coherent narrowband Smith-Purcell radiation (SPR) in the low-to-mid terahertz range. The device is a planar Gunn diode with a metallic grating deposited near the drift region. Stimulated SPR is generated as domains move under the grating. Radiation frequency is determined by the domain velocity and grating period—it is not transit-time limited. The approach is photolithographically tunable, readily scales to arrays, and is compatible with any planar Gunn technology. Integration with a planar antenna improves radiation efficiency and enables far-field optimization. We develop an analytic theory of the devices which agrees well with simulations. Results indicate that this method may achieve technologically relevant power density levels and warrants experimental investigation.

  18. An electrically injected photon-pair source at room temperature

    CERN Document Server

    Boitier, Fabien; Autebert, Claire; Lemaître, Aristide; Galopin, Elisabeth; Manquest, Christophe; Sirtori, Carlo; Favero, Ivan; Leo, Giuseppe; Ducci, Sara

    2013-01-01

    One of the main challenges for future quantum information technologies is miniaturization and integration of high performance components in a single chip. In this context, electrically driven sources of non-classical states of light have a clear advantage over optically driven ones. Here we demonstrate the first electrically driven semiconductor source of photon pairs working at room temperature and telecom wavelength. The device is based on type-II intracavity Spontaneous Parametric Down-Conversion in an AlGaAs laser diode and generates pairs at 1.57 $\\mu$m. Time-correlation measurements of the emitted pairs give an internal generation efficiency of $7 \\times 10^{-11}$ pairs/injected electron. The capability of our platform to support generation, manipulation and detection of photons opens the way to the demonstration of massively parallel systems for complex quantum operations.

  19. Room temperature magnesium electrorefining by using non-aqueous electrolyte

    Science.gov (United States)

    Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Dilasari, Bonita; Ku, Heesuk; Kim, Hansu; Kwon, Kyungjung; Lee, Churl Kyoung

    2016-09-01

    The increasing usage of magnesium inevitably leads to a fast increase in magnesium scrap, and magnesium recycling appears extremely beneficial for cost reduction, preservation of natural resources and protection of the environment. Magnesium refining for the recovery of high purity magnesium from metal scrap alloy (AZ31B composed of magnesium, aluminum, zinc, manganese and copper) at room temperature is investigated with a non-aqueous electrolyte (tetrahydrofuran with ethyl magnesium bromide). A high purity (99.999%) of electrorefined magneisum with a smooth and dense surface is obtained after potentiostatic electrolysis with an applied voltage of 2 V. The selective dissolution of magnesium from magnesium alloy is possible by applying an adequate potential considering the tolerable impurity level in electrorefined magnesium and processing time. The purity estimation method suggested in this study can be useful in evaluating the maximum content of impurity elements.

  20. Room-temperature terahertz detection based on CVD graphene transistor

    Institute of Scientific and Technical Information of China (English)

    杨昕昕; 孙建东; 秦华; 吕利; 苏丽娜; 闫博; 李欣幸; 张志鹏; 方靖岳

    2015-01-01

    We report the fabrication and characterization of a single-layer graphene field-effect terahertz detector, which is cou-pled with dipole-like antennas based on the self-mixing detector model. The graphene is grown by chemical vapor deposi-tion and then transferred onto an SiO2/Si substrate. We demonstrate room-temperature detection at 237 GHz. The detector could offer a voltage responsivity of 0.1 V/W and a noise equivalent power of 207 nW/Hz1/2. Our modeling indicates that the observed photovoltage in the p-type gated channel can be well fit by the self-mixing theory. A different photoresponse other than self-mixing may apply for the n-type gated channel.

  1. Room temperature luminescence and ferromagnetism of AlN:Fe

    Directory of Open Access Journals (Sweden)

    H. Li

    2016-06-01

    Full Text Available AlN:Fe polycrystalline powders were synthesized by a modified solid state reaction (MSSR method. Powder X-ray diffraction and transmission electron microscopy results reveal the single phase nature of the doped samples. In the doped AlN samples, Fe is in Fe2+ state. Room temperature ferromagnetic behavior is observed in AlN:Fe samples. Two photoluminescence peaks located at about 592 nm (2.09 eV and 598 nm (2.07 eV are observed in AlN:Fe samples. Our results suggest that AlN:Fe is a potential material for applications in spintronics and high power laser devices.

  2. Room-temperature ferromagnetism in pure ZnO nanoflowers

    Science.gov (United States)

    Bie, Xiaofei; Wang, Chunzhong; Ehrenberg, H.; Wei, Yingjin; Chen, Gang; Meng, Xing; Zou, Guangtian; Du, Fei

    2010-08-01

    ZnO nanoflowers are synthesized by hydrothermal method. The morphology of ZnO is captured by SEM, TEM and HRTEM, which is composed of closely packed nanorods of about 100 nm in diameter and 1 μm in length. The ZFC/FC curves show superparamagnetic features. The abnormal increase in magnetization curves below 14 K comes from the isolated vacancy clusters with no interaction. The magnetic hysteresis at 300 K displays saturation state and confirms room-temperature ferromagnetism. While the magnetic hysteresis at 5 K shows nonsaturation state due to the enhanced effects of vacancy clusters. The O 1s XPS results can be fitted to three Gaussian peaks. The existence of medium-binding energy located at 531.16 eV confirms the deficiency of O ions at the surface of ZnO nanoflowers.

  3. Room-temperature spin-photon interface for quantum networks

    Science.gov (United States)

    Hong, Fang-Yu; Fu, Jing-Li; Wu, Yan; Zhu, Zhi-Yan

    2017-02-01

    Although remarkable progress has been achieved recently, to construct an optical cavity where a nitrogen-vacancy (NV) colour centre in diamond is coupled to an optical field in the strong coupling regime is rather difficult. We propose an architecture for a scalable quantum interface capable of interconverting photonic and NV spin qubits, which can work well without the strong coupling requirement. The dynamics of the interface applies an adiabatic passage to sufficiently reduce the decoherence from an excited state of a NV colour centre in diamond. This quantum interface can accomplish many quantum network operations like state transfer and entanglement distribution between qubits at distant nodes. Exact numerical simulations show that high-fidelity quantum interface operations can be achieved under room-temperature and realistic experimental conditions.

  4. Quantum memory, entanglement and sensing with room temperature atoms

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, K; Wasilewski, W; Krauter, H; Fernholz, T; Nielsen, B M; Petersen, J M; Renema, J J; Balabas, M V; Wolf, M M; Mueller, J H; Polzik, E S [Niels Bohr Institute, Danish Quantum Optics Center QUANTOP, Copenhagen University, Blegdamsvej 17, 2100 Copenhagen (Denmark); Owari, M; Plenio, M B [Institut fuer Theoretische Physik, Universitaet Ulm, Albert-Einstein Allee 11, D-89069 Ulm (Germany); Serafini, A [University College London, Department of Physics and Astronomy, Gower Street, London WC1E 6BT (United Kingdom); Muschik, C A; Cirac, J I, E-mail: polzik@nbi.d [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching (Germany)

    2011-01-10

    Room temperature atomic ensembles in a spin-protected environment are useful systems both for quantum information science and metrology. Here we utilize a setup consisting of two atomic ensembles as a memory for quantum information initially encoded in the polarization state of two entangled light modes. We also use the ensembles as a radio frequency entanglement-assisted magnetometer with projection noise limited sensitivity below femtoTesla/{radical}Hz. The performance of the quantum memory as well as the magnetometer was improved by spin-squeezed or entangled atomic states generated by quantum non demolition measurements. Finally, we present preliminary results of long lived entangled atomic states generated by dissipation. With the method presented, one should be able to generate an entangled steady state.

  5. Experimental evidence for ice formation at room temperature.

    Science.gov (United States)

    Jinesh, K B; Frenken, J W M

    2008-07-18

    The behavior of water under extreme confinement and, in particular, the lubrication properties under such conditions are subjects of long-standing controversy. Using a dedicated, high-resolution friction force microscope, scanning a sharp tungsten tip over a graphite surface, we demonstrate that water nucleating between the tip and the surface due to capillary condensation rapidly transforms into crystalline ice at room temperature. At ultralow scan speeds and modest relative humidities, we observe that the tip exhibits stick-slip motion with a period of 0.38+/-0.03 nm, very different from the graphite lattice. We interpret this as the consequence of the repeated sequence of shear-induced fracture and healing of the crystalline condensate. This phenomenon causes a significant increase of the friction force and introduces relaxation time scales of seconds for the rearrangements after shearing.

  6. Extraction of organic compounds with room temperature ionic liquids.

    Science.gov (United States)

    Poole, Colin F; Poole, Salwa K

    2010-04-16

    Room temperature ionic liquids are novel solvents with a rather specific blend of physical and solution properties that makes them of interest for applications in separation science. They are good solvents for a wide range of compounds in which they behave as polar solvents. Their physical properties of note that distinguish them from conventional organic solvents are a negligible vapor pressure, high thermal stability, and relatively high viscosity. They can form biphasic systems with water or low polarity organic solvents and gases suitable for use in liquid-liquid and gas-liquid partition systems. An analysis of partition coefficients for varied compounds in these systems allows characterization of solvent selectivity using the solvation parameter model, which together with spectroscopic studies of solvent effects on probe substances, results in a detailed picture of solvent behavior. These studies indicate that the solution properties of ionic liquids are similar to those of polar organic solvents. Practical applications of ionic liquids in sample preparation include extractive distillation, aqueous biphasic systems, liquid-liquid extraction, liquid-phase microextraction, supported liquid membrane extraction, matrix solvents for headspace analysis, and micellar extraction. The specific advantages and limitations of ionic liquids in these studies is discussed with a view to defining future uses and the need not to neglect the identification of new room temperature ionic liquids with physical and solution properties tailored to the needs of specific sample preparation techniques. The defining feature of the special nature of ionic liquids is not their solution or physical properties viewed separately but their unique combinations when taken together compared with traditional organic solvents.

  7. Wide bandwidth nanowire electromechanics on insulating substrates at room temperature

    Science.gov (United States)

    Sebastian, Abhilash; Mathew, John; Sengupta, Shamashis; Gokhale, Maheshwar; Bhattacharya, Arnab; Deshmukh, Mandar

    2013-03-01

    We present a simple fabrication scheme for nano-scale devices on insulating substrates. Doubly clamped InAs nanowire resonators with local gate configuration are fabricated on sapphire substrates. Parasitic capacitance is reduced on insulating substrates thus enabling measurements at all temperatures and particularly above room temperature, an essential requirement for NEMS sensors. Mechanical motion of the nanowire is capacitively actuated and detected using a network analyser. This technique provides wide bandwidth radio frequency transduction and allows the nanowire oscillations to be probed at a much faster rate compared to mixing techniques. Both in-plane and out-of-plane vibrational modes of the nanowire are observed and the non-linear response of the resonators is studied. Quality factor of the resonator increases at low temperatures. We also study the relation between mechanical motion and thermal strains in the nanowire. This opens up a new approach in studying thermal properties of nanostructures. Our method of fabrication can be extended to NEMS devices on flexible substrates and other nanostructures.

  8. Tuning magnetic spirals beyond room temperature with chemical disorder

    Science.gov (United States)

    Morin, Mickaël; Canévet, Emmanuel; Raynaud, Adrien; Bartkowiak, Marek; Sheptyakov, Denis; Ban, Voraksmy; Kenzelmann, Michel; Pomjakushina, Ekaterina; Conder, Kazimierz; Medarde, Marisa

    2016-12-01

    In the past years, magnetism-driven ferroelectricity and gigantic magnetoelectric effects have been reported for a number of frustrated magnets featuring ordered spiral magnetic phases. Such materials are of high-current interest due to their potential for spintronics and low-power magnetoelectric devices. However, their low-magnetic ordering temperatures (typically <100 K) greatly restrict their fields of application. Here we demonstrate that the onset temperature of the spiral phase in the perovskite YBaCuFeO5 can be increased by more than 150 K through a controlled manipulation of the Fe/Cu chemical disorder. Moreover, we show that this novel mechanism can stabilize the magnetic spiral state of YBaCuFeO5 above the symbolic value of 25 °C at zero magnetic field. Our findings demonstrate that the properties of magnetic spirals, including its wavelength and stability range, can be engineered through the control of chemical disorder, offering a great potential for the design of materials with magnetoelectric properties beyond room temperature.

  9. Advances in crystal growth, device fabrication and characterization of thallium bromide detectors for room temperature applications

    Science.gov (United States)

    Datta, Amlan; Moed, Demi; Becla, Piotr; Overholt, Matthew; Motakef, Shariar

    2016-10-01

    Thallium bromide (TlBr) is a promising room-temperature radiation detector candidate with excellent charge transport properties. However, several critical issues need to be addressed before deployment of this material for long-term field applications can be realized. In this paper, progress made towards solving some of these challenges is discussed. The most significant factors for achieving long-term performance stability for TlBr devices include residual stress as generated during crystal growth and fabrication processes, surface conditions, and the choice of contact metal. Modifications to the commonly used traveling molten zone growth technique for TlBr crystals can significantly minimize the stresses generated by large temperature gradients near the melt-solid interface of the growing crystal. Plasma processing techniques were introduced for the first time to modify the Br-etched TlBr surfaces, which resulted in improvements to the surface conditions, and consequently the spectroscopic response of the detectors. Palladium electrodes resulted a 20-fold improvement in the room-temperature device lifetime when compared to its Br-etched Pt counterpart.

  10. Room-temperature single-photon generation from solitary dopants of carbon nanotubes

    Science.gov (United States)

    Ma, Xuedan; Hartmann, Nicolai F.; Baldwin, Jon K. S.; Doorn, Stephen K.; Htoon, Han

    2015-08-01

    On-demand single-photon sources capable of operating at room temperature and the telecom wavelength range of 1,300-1,500 nm hold the key to the realization of novel technologies that span from sub-diffraction imaging to quantum key distribution and photonic quantum information processing. Here, we show that incorporation of undoped (6,5) single-walled carbon nanotubes into a SiO2 matrix can lead to the creation of solitary oxygen dopant states capable of fluctuation-free, room-temperature single-photon emission in the 1,100-1,300 nm wavelength range. We investigated the effects of temperature on photoluminescence emission efficiencies, fluctuations and decay dynamics of the dopant states and determined the conditions most suitable for the observation of single-photon emission. This emission can in principle be extended to 1,500 nm by doping of smaller-bandgap single-walled carbon nanotubes. This easy tunability presents a distinct advantage over existing defect centre single-photon emitters (for example, diamond defect centres). Our SiO2-encapsulated sample also presents exciting opportunities to apply Si/SiO2-based micro/nano-device fabrication techniques in the development of electrically driven single-photon sources and integration of these sources into quantum photonic devices and networks.

  11. Proton conducting membrane containing room temperature ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Sekhon, S.S. [Department of Applied Physics, Guru Nanak Dev University, Amritsar 143005 (India) and Polymer Electrolyte Fuel Cell Research Department, Korea Institute of Energy Research, 71-2, Jang-Dong, Yusong-gu, Daejeon 305-343 (Korea, Republic of)]. E-mail: sekhon_apd@yahoo.com; Krishnan, P. [Polymer Electrolyte Fuel Cell Research Department, Korea Institute of Energy Research, 71-2, Jang-Dong, Yusong-gu, Daejeon 305-343 (Korea, Republic of); Singh, Boor [Department of Applied Physics, Guru Nanak Dev University, Amritsar 143005 (India); Yamada, K. [Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima (Japan); Kim, C.S. [Polymer Electrolyte Fuel Cell Research Department, Korea Institute of Energy Research, 71-2, Jang-Dong, Yusong-gu, Daejeon 305-343 (Korea, Republic of)

    2006-12-01

    A new proton conducting membrane containing room temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium trifluoromethanesulfonylimide (DMOImTFSI) and polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP) has been developed in the present work. The addition of bis(trifluoromethanesulphonyl)imide (HN(CF{sub 3}SO{sub 2}){sub 2}) to this membrane results in an increase in conductivity by one order of magnitude at 25 deg. C. The membrane shows a conductivity of 2.74 x 10{sup -3} S/cm at 130 deg. C along with good mechanical stability. The membrane was tested in a commercial fuel cell test station at 100 deg. C with dry hydrogen and oxygen gas reactants using Pt/C electrodes. The membrane containing the ionic liquid has been found to be electroactive for hydrogen oxidation and oxygen reduction at the platinum electrode and can be developed for use in proton exchange membrane fuel cell (PEMFC) under non-humid conditions at elevated temperatures.

  12. Engineering Room-temperature Superconductors Via ab-initio Calculations

    Science.gov (United States)

    Gulian, Mamikon; Melkonyan, Gurgen; Gulian, Armen

    The BCS, or bosonic model of superconductivity, as Little and Ginzburg have first argued, can bring in superconductivity at room temperatures in the case of high-enough frequency of bosonic mode. It was further elucidated by Kirzhnitset al., that the condition for existence of high-temperature superconductivity is closely related to negative values of the real part of the dielectric function at finite values of the reciprocal lattice vectors. In view of these findings, the task is to calculate the dielectric function for real materials. Then the poles of this function will indicate the existence of bosonic excitations which can serve as a "glue" for Cooper pairing, and if the frequency is high enough, and the dielectric matrix is simultaneously negative, this material is a good candidate for very high-Tc superconductivity. Thus, our approach is to elaborate a methodology of ab-initio calculation of the dielectric function of various materials, and then point out appropriate candidates. We used the powerful codes (TDDF with the DP package in conjunction with ABINIT) for computing dielectric responses at finite values of the wave vectors in the reciprocal lattice space. Though our report is concerned with the particular problem of superconductivity, the application range of the data processing methodology is much wider. The ability to compute the dielectric function of existing and still non-existing (though being predicted!) materials will have many more repercussions not only in fundamental sciences but also in technology and industry.

  13. Hydrogen permeation in iron and nickel alloys around room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, T., E-mail: t-otsuka@nucl.kyushu-u.ac.jp; Shinohara, M.; Horinouchi, H.; Tanabe, T.

    2013-11-15

    Hydrogen permeation and diffusion coefficients in alloys of iron (Fe) and nickel (Ni) with the Ni content of 5, 9, and 20 at.% and a crystal structure of α/α′ phase have been examined around room temperature (RT) using a tritium-tracer hydrogen-permeation experiment. Hydrogen permeation coefficients around RT agree well with values extrapolated from literature data obtained at higher temperatures for the respective alloys. On the other hand, apparent hydrogen diffusion coefficients determined using the time-lag method are several orders of magnitude smaller than extrapolated from the literature data. This could be caused by surface blocking and/or barrier effects due to surface oxide and/or other impurities. Initially, hydrogen permeation is suppressed by the existence of the surface oxide. It appears that hydrogen, mostly at the upstream side or even at the downstream side, can reduce and remove the surface oxides so that normal hydrogen steady-state permeation can occur without surface blocking or barrier effects. Thus, true hydrogen diffusion coefficients for respective Fe–Ni alloys during steady-state permeation must be much larger than those estimated from the time-lag method.

  14. Investigation of Room temperature Ferromagnetism in Mn doped Ge

    Science.gov (United States)

    Colakerol Arslan, Leyla; Toydemir, Burcu; Onel, Aykut Can; Ertas, Merve; Doganay, Hatice; Gebze Inst of Tech Collaboration; Research Center Julich Collaboration

    2014-03-01

    We present a systematic investigation of structural, magnetic and electronic properties of MnxGe1 -x single crystals. MnxGe1-x films were grown by sequential deposition of Ge and Mn by molecular-beam epitaxy at low substrate temperatures in order to avoid precipitation of ferromagnetic Ge-Mn intermetallic compounds. Reflected high energy electron diffraction and x-ray diffraction observations revealed that films are epitaxially grown on Si (001) substrates from the initial stage without any other phase formation. Magnetic measurements carried out using a physical property measurement system showed that all samples exhibited ferromagnetism at room temperature. Electron spin resonance indicates the presence of magnetically ordered localized spins of divalent Mn ions. X-ray absorption measurements at the Mn L-edge confirm significant substitutional doping of Mn into Ge-sites. The ferromagnetism was mainly induced by Mn substitution for Ge site, and indirect exchange interaction of these magnetic ions with the intrinsic charge carriers is the origin of ferromagnetism. The magnetic interactions were better understood by codoping with nonmagnetic impurities. This work was supported by Marie-Curie Reintegration Grant (PIRG08-GA-2010-276973).

  15. Robust isothermal electric control of exchange bias at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    He, X.; Vescovo, E.; Wang, Y.; Caruso, A.N.; Belashchenko, K.D.; Dowben, P.A.; Binek, C.

    2010-06-20

    Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with high-speed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr{sub 2}O{sub 3} has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr{sub 2}O{sub 3} single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias field between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This effect reflects the switching of the bulk antiferromagnetic domain state and the interface magnetization coupled to it. The switchable exchange bias sets in exactly at the bulk Neel temperature.

  16. Robust isothermal electric control of exchange bias at room temperature.

    Science.gov (United States)

    He, Xi; Wang, Yi; Wu, Ning; Caruso, Anthony N; Vescovo, Elio; Belashchenko, Kirill D; Dowben, Peter A; Binek, Christian

    2010-07-01

    Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with high-speed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr(2)O(3) has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr(2)O(3) single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias field between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This effect reflects the switching of the bulk antiferromagnetic domain state and the interface magnetization coupled to it. The switchable exchange bias sets in exactly at the bulk Néel temperature.

  17. Dielectric Behavior of Biomaterials at Different Frequencies on Room Temperature

    Science.gov (United States)

    Shrivastava, B. D.; Barde, Ravindra; Mishra, A.; Phadke, S.

    2014-09-01

    Propagation of electromagnetic (EM) waves in radiofrequency (RF) and microwave systems is described mathematically by Maxwell's equations with corresponding boundary conditions. Dielectric properties of lossless and lossy materials influence EM field distribution. For a better understanding of the physical processes associated with various RF and microwave devices, it is necessary to know the dielectric properties of media that interact with EM waves. For telecommunication and radar devices, variations of complex dielectric permittivity (referring to the dielectric property) over a wide frequency range are important. For RF and microwave applicators intended for thermal treatments of different materials at ISM (industrial, scientific, medical) frequencies, one needs to study temperature and moisture content dependencies of the Permittivity of the treated materials. Many techniques have been developed for the measurement of materials. In the present paper authors used Bones and scales of Fish taken from Narmada River (Rajghat Dist. Barwani) as biomaterials. Dielectric properties of Biomaterials with the frequency range from 1Hz to 10 MHz at room temperature with low water content were measured by in-situ performance dielectric kit. Analysis has been done by Alpha high performance impedance analyzer and LCR meters. The experimental work were carried out in Inter University Consortium UGC-DAE, CSR center Indore MP. Measured value indicates the dielectric constant (ɛ') dielectric loss (ɛ") decreases with increasing frequency while conductivity (σ) increases with frequency increased.

  18. Room temperature triplet state spectroscopy of organic semiconductors.

    Science.gov (United States)

    Reineke, Sebastian; Baldo, Marc A

    2014-01-21

    Organic light-emitting devices and solar cells are devices that create, manipulate, and convert excited states in organic semiconductors. It is crucial to characterize these excited states, or excitons, to optimize device performance in applications like displays and solar energy harvesting. This is complicated if the excited state is a triplet because the electronic transition is 'dark' with a vanishing oscillator strength. As a consequence, triplet state spectroscopy must usually be performed at cryogenic temperatures to reduce competition from non-radiative rates. Here, we control non-radiative rates by engineering a solid-state host matrix containing the target molecule, allowing the observation of phosphorescence at room temperature and alleviating constraints of cryogenic experiments. We test these techniques on a wide range of materials with functionalities spanning multi-exciton generation (singlet exciton fission), organic light emitting device host materials, and thermally activated delayed fluorescence type emitters. Control of non-radiative modes in the matrix surrounding a target molecule may also have broader applications in light-emitting and photovoltaic devices.

  19. A computed room temperature line list for phosphine

    Science.gov (United States)

    Sousa-Silva, Clara; Yurchenko, Sergei N.; Tennyson, Jonathan

    2013-06-01

    An accurate and comprehensive room temperature rotation-vibration transition line list for phosphine (31PH3) is computed using a newly refined potential energy surface and a previously constructed ab initio electric dipole moment surface. Energy levels, Einstein A coefficients and transition intensities are computed using these surfaces and a variational approach to the nuclear motion problem as implemented in the program TROVE. A ro-vibrational spectrum is computed, covering the wavenumber range 0-8000 cm-1. The resulting line list, which is appropriate for temperatures up to 300 K, consists of a total of 137 million transitions between 5.6 million energy levels. Several of the band centres are shifted to better match experimental transition frequencies. The line list is compared to the most recent HITRAN database and other laboratorial sources. Transition wavelengths and intensities are generally found to be in good agreement with the existing experimental data, with particularly close agreement for the rotational spectrum. An analysis of the comparison between the theoretical data created and the existing experimental data is performed, and suggestions for future improvements and assignments to the HITRAN database are made.

  20. InSb Mid-Infrared Photon Detector for Room-Temperature Operation

    Science.gov (United States)

    Ueno, Koichiro; Gomes Camargo, Edson; Katsumata, Takashi; Goto, Hiromasa; Kuze, Naohiro; Kangawa, Yoshihiro; Kakimoto, Koichi

    2013-09-01

    We developed a small InSb mid-infrared (2-7 µm wavelength range) photon detector that operates at room temperature. The photodiode was made from (hetero epitaxial) InSb layers that were grown on a semi-insulating GaAs substrate by molecular beam epitaxy. To suppress the effects of the diffusion current of the p-i-n photodiode, we used an AlInSb barrier layer that raises the resistance of the photodiode. We also optimized the device's doping concentration and the infrared incidence window structure. These optimization steps realized high photoelectric current output in a room-temperature environment. We also increased the signal-to-noise ratio of the detector by connecting multiple photodiodes in series. The size of this detector is 1.9×2.7×0.4 mm3 and the detectivity is 2.8×108 cm Hz1/2/W at 300 K. This is a practical IR detector that can be used in general signal amplification ICs.

  1. Room temperature lasing in GeSn alloys: A path to CMOS-compatible infrared lasers

    Science.gov (United States)

    Li, Zairui; Zhao, Yun; Gallagher, James; Menéndez, José; Kouvetakis, John; Agha, Imad; Mathews, Jay

    The semiconductor industry has been pushing silicon photonics development for many years, resulting in the realization of many CMOS-compatible optoelectronic devices. However, one challenge that has not been overcome is the development of Si-based lasers. Recently, GeSn alloys grown on Si have shown much promise in the field of infrared optoelectronics. These alloy films are compatible with CMOS processing, have band gaps in the infrared, and the band structure of GeSn can be tuned via Sn concentration to induce direct band gap emission. In this work, we report on room temperature lasing in optically-pumped waveguides fabricated from GeSn films grown epitaxially on Si(100) substrates. The waveguides were defined using standard UV photolithography and dry-etched in a Cl plasma. The end facets were mirror polished, and Al was deposited on one facet to enhance cavity quality. The waveguides were optically-pumped using a 976nm wavelength solid-state laser, and the corresponding emission was measured. The dependence of the emission power on the pump power shows a clear transition between spontaneous and stimulated emission, thereby demonstrating room temperature lasing.

  2. Porous aluminum room temperature anodizing process in a fluorinated-oxalic acid solution

    Science.gov (United States)

    Dhahri, S.; Fazio, E.; Barreca, F.; Neri, F.; Ezzaouia, H.

    2016-08-01

    Anodizing of aluminum is used for producing porous insulating films suitable for different applications in electronics and microelectronics. Porous-type aluminum films are most simply realized by galvanostatic anodizing in aqueous acidic solutions. The improvement in application of anodizing technique is associated with a substantial reduction of the anodizing voltage at appropriate current densities as well as to the possibility to carry out the synthesis process at room temperature in order to obtain a self-planarizing dielectric material incorporated in array of super-narrow metal lines. In this work, the anodizing of aluminum to obtain porous oxide was carried out, at room temperature, on three different substrates (glass, stainless steel and aluminum), using an oxalic acid-based electrolyte with the addition of a relatively low amount of 0.4 % of HF. Different surface morphologies, from nearly spherical to larger porous nanostructures with smooth edges, were observed by means of scanning electron microscopy. These evidences are explained by considering the formation, transport and adsorption of the fluorine species which react with the Al3+ ions. The behavior is also influenced by the nature of the original substrate.

  3. Improved x-ray spectroscopy with room temperature CZT detectors.

    Science.gov (United States)

    Fritz, Shannon G; Shikhaliev, Polad M; Matthews, Kenneth L

    2011-09-07

    Compact, room temperature x-ray spectroscopy detectors are of interest in many areas including diagnostic x-ray imaging, radiation protection and dosimetry. Room temperature cadmium zinc telluride (CZT) semiconductor detectors are promising candidates for these applications. One of the major problems for CZT detectors is low-energy tailing of the energy spectrum due to hole trapping. Spectral post-correction methods to correct the tailing effect do not work well for a number of reasons; thus it is advisable to eliminate the hole trapping effect in CZT using physical methods rather than correcting an already deteriorated energy spectrum. One method is using a CZT detector with an electrode configuration which modifies the electric field in the CZT volume to decrease low-energy tailing. Another method is to irradiate the CZT surface at a tilted angle, which modifies depth of interaction to decrease low-energy tailing. Neither method alone, however, eliminates the tailing effect. In this work, we have investigated the combination of modified electric field and tilted angle irradiation in a single detector to further decrease spectral tailing. A planar CZT detector with 10 × 10 × 3 mm³ size and CZT detector with 5 × 5 × 5 mm³ size and cap-shaped electrode were used in this study. The cap-shaped electrode (referred to as CAPture technology) modifies the electric field distribution in the CZT volume and decreases the spectral tailing effect. The detectors were investigated at 90° (normal) and 30° (tilted angle) irradiation modes. Two isotope sources with 59.6 and 122 keV photon energies were used for gamma-ray spectroscopy experiments. X-ray spectroscopy was performed using collimated beams at 60, 80 and 120 kVp tube voltages, in both normal and tilted angle irradiation. Measured x-ray spectra were corrected for K x-ray escape fractions that were calculated using Monte Carlo methods. The x-ray spectra measured with tilted angle CAPture detector at 60, 80 and 120

  4. Room Temperature InP DFB Laser Array Directly Grown on (001) Silicon

    CERN Document Server

    Wang, Zhechao; Pantouvaki, Marianna; Guo, Weiming; Absil, Philippe; Van Campenhout, Joris; Merckling, Clement; Van Thourhout, Dries

    2015-01-01

    Fully exploiting the silicon photonics platform requires a fundamentally new approach to realize high-performance laser sources that can be integrated directly using wafer-scale fabrication methods. Direct band gap III-V semiconductors allow efficient light generation but the large mismatch in lattice constant, thermal expansion and crystal polarity makes their epitaxial growth directly on silicon extremely complex. Here, using a selective area growth technique in confined regions, we surpass this fundamental limit and demonstrate an optically pumped InP-based distributed feedback (DFB) laser array grown on (001)-Silicon operating at room temperature and suitable for wavelength-division-multiplexing applications. The novel epitaxial technology suppresses threading dislocations and anti-phase boundaries to a less than 20nm thick layer not affecting the device performance. Using an in-plane laser cavity defined by standard top-down lithographic patterning together with a high yield and high uniformity provides ...

  5. Scalable Architecture for a Room Temperature Solid-State Quantum Information Processor

    CERN Document Server

    Yao, Norman Y; Gorshkov, Alexey V; Maurer, Peter C; Giedke, Geza; Cirac, J Ignacio; Lukin, Mikhail D

    2010-01-01

    The realization of a scalable quantum information processor has emerged over the past decade as one of the central challenges at the interface of fundamental science and engineering. Much progress has been made towards this goal. Indeed, quantum operations have been demonstrated on several trapped ion qubits, and other solid-state systems are approaching similar levels of control. Extending these techniques to achieve fault-tolerant operations in larger systems with more qubits remains an extremely challenging goal, in part, due to the substantial technical complexity of current implementations. Here, we propose and analyze an architecture for a scalable, solid-state quantum information processor capable of operating at or near room temperature. The architecture is applicable to realistic conditions, which include disorder and relevant decoherence mechanisms, and includes a hierarchy of control at successive length scales. Our approach is based upon recent experimental advances involving Nitrogen-Vacancy colo...

  6. Room temperature broadband coherent terahertz emission induced by dynamical photon drag in graphene

    CERN Document Server

    Maysonnave, J; Wang, F; Maero, S; Berger, C; de Heer, W; Norris, T B; De Vaulchier, L A; Dhillon, S; Tignon, J; Ferreira, R; Mangeney, J

    2015-01-01

    Nonlinear couplings between photons and electrons in new materials give rise to a wealth of interesting nonlinear phenomena. This includes frequency mixing, optical rectification or nonlinear current generation, which are of particular interest for generating radiation in spectral regions that are difficult to access, such as the terahertz gap. Owing to its specific linear dispersion and high electron mobility at room temperature, graphene is particularly attractive for realizing strong nonlinear effects. However, since graphene is a centrosymmetric material, second-order nonlinearities a priori cancel, which imposes to rely on less attractive third-order nonlinearities. It was nevertheless recently demonstrated that dc-second-order nonlinear currents as well as ultrafast ac-currents can be generated in graphene under optical excitation. The asymmetry is introduced by the excitation at oblique incidence, resulting in the transfer of photon momentum to the electron system, known as the photon drag effect. Here...

  7. Transfer of CVD-grown graphene for room temperature gas sensors

    Science.gov (United States)

    Rigoni, F.; Maiti, R.; Baratto, C.; Donarelli, M.; MacLeod, J.; Gupta, B.; Lyu, M.; Ponzoni, A.; Sberveglieri, G.; Motta, N.; Faglia, G.

    2017-10-01

    An easy transfer procedure to obtain graphene-based gas sensing devices operating at room temperature (RT) is presented. Starting from chemical vapor deposition-grown graphene on copper foil, we obtained single layer graphene which could be transferred onto arbitrary substrates. In particular, we placed single layer graphene on top of a SiO2/Si substrate with pre-patterned Pt electrodes to realize a chemiresistor gas sensor able to operate at RT. The responses to ammonia (10, 20, 30 ppm) and nitrogen dioxide (1, 2, 3 ppm) are shown at different values of relative humidity, in dark and under 254 nm UV light. In order to check the sensor selectivity, gas response has also been tested towards hydrogen, ethanol, acetone and carbon oxide. Finally, a model based on linear dispersion relation characteristic of graphene, which take into account humidity and UV light effects, has been proposed.

  8. Low-temperature process steps for realization of non-volatile memory devices

    NARCIS (Netherlands)

    Brunets, I.; Boogaard, A.; Aarnink, A.A.I.; Kovalgin, A.Y.; Wolters, R.A.M.; Holleman, J.; Schmitz, J.

    2007-01-01

    In this work, the low-temperature process steps required for the realization of nano-crystal non-volatile memory cells are discussed. An amorphous silicon film, crystallized using a diode pumped solid state green laser irradiating at 532 nm, is proposed as an active layer. The deposition of the subs

  9. Proactive aquatic ecotoxicological assessment of room-temperature ionic liquids

    Science.gov (United States)

    Kulacki, K.J.; Chaloner, D.T.; Larson, J.H.; Costello, D.M.; Evans-White, M. A.; Docherty, K.M.; Bernot, R.J.; Brueseke, M.A.; Kulpa, C.F.; Lamberti, G.A.

    2011-01-01

    Aquatic environments are being contaminated with a myriad of anthropogenic chemicals, a problem likely to continue due to both unintentional and intentional releases. To protect valuable natural resources, novel chemicals should be shown to be environmentally safe prior to use and potential release into the environment. Such proactive assessment is currently being applied to room-temperature ionic liquids (ILs). Because most ILs are water-soluble, their effects are likely to manifest in aquatic ecosystems. Information on the impacts of ILs on numerous aquatic organisms, focused primarily on acute LC50 and EC50 endpoints, is now available, and trends in toxicity are emerging. Cation structure tends to influence IL toxicity more so than anion structure, and within a cation class, the length of alkyl chain substituents is positively correlated with toxicity. While the effects of ILs on several aquatic organisms have been studied, the challenge for aquatic toxicology is now to predict the effects of ILs in complex natural environments that often include diverse mixtures of organisms, abiotic conditions, and additional stressors. To make robust predictions about ILs will require coupling of ecologically realistic laboratory and field experiments with standard toxicity bioassays and models. Such assessments would likely discourage the development of especially toxic ILs while shifting focus to those that are more environmentally benign. Understanding the broader ecological effects of emerging chemicals, incorporating that information into predictive models, and conveying the conclusions to those who develop, regulate, and use those chemicals, should help avoid future environmental degradation. ?? 2011 Bentham Science Publishers Ltd.

  10. Resonantly pumped room temperature Ho:LuVO₄ laser.

    Science.gov (United States)

    Yao, B Q; Cui, Z; Duan, X M; Du, Y Q; Han, L; Shen, Y J

    2014-11-01

    Spectroscopic characterization of a Ho:LuVO4 crystal grown by the Czochralski method has been performed, including the absorption and emission spectra. We demonstrate a 2 μm room temperature Ho:LuVO4 laser, resonantly pumped by a 1.94 μm Tm:YAP laser. By use of an output coupler with T=10% transmission, the Ho:LuVO4 laser generated continuous-wave output power of 2.5 W at 2074.18 nm, with a beam quality factor of Mx2=My2=1.3, for a total incident pump power of 19.4 W. The slope efficiency with respect to the pump power was 17.6%, and the optical-to-optical efficiency was 12.9%. Moreover, we obtained a Ho:LuVO4 laser that operated at 2073.77 and 2055.27 nm, by using different output couplers with transmissions of T=15 and 30%.

  11. Dissolution of Konjac Glucomannan with Room Temperature Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    SHEN Chunhui; LI Denian; ZHANG Ling; WAN Chao; GAO Shanjun

    2011-01-01

    Two kinds of new room temperature ionic liquids(RTILs),1-allyl-3-methylimidazolium chloride(AMIMC1)and 1-butyl-3-methylimidazolium chloride(BMIMC1),were synthesized and used for the dissolution of konjac glucomannan(KGM).The experimental results showed that the solubility of KGM in AMIMC1 was better than that in BMIMC1.Regenerated KGM were obtained by adding anhydrous alcohol to the KGM/ionic liquids solutions.Solubility,molecular weight,structure,and thermal property of the regenerated KGM were investigated by polarized optical microscopy(POM),viscosimetry,infrared spectroscopy(IR),X-ray diffraction technique(XRD),thermogravimetry,(TG)and differential scanning calorimetry(DSC).It was demonstrated that the viscosity-averaged molecular weight of the KGM samples decreased after regeneration because of the molecular degradation of KGM.Results from IR and XRD indicated that the chemical structure and the crystalline form of regenerated KGM were not changed.Results from TG and DSC showed that the thermal stability of the regenerated KGM samples only slightly decreased.These results suggest that AMIMC1 and BMIMC1 are direct and effective solvents for KGM.

  12. Electrosynthesis in room-temperature ionic liquids: benzaldehyde reduction

    Energy Technology Data Exchange (ETDEWEB)

    Doherty, Andrew P.; Brooks, Claudine A

    2004-09-15

    The electrochemical reduction of benzaldehyde at Pt microelectrodes in 1-butyl-1-methyl pyrrolidinium triflimide ([Bmpyr][NTF{sub 2}]) room temperature ionic liquid is reported. At high potential sweep rates (>1000 V s{sup -1}) reduction occurs as two reversible one-electron reduction processes corresponding to the reversible formation of the radical anion (at -1.6 V versus Pt) and the dianion species (at -2.2 V versus Pt). The second order rate constant for radical anion-radical anion dimerisation was 1.4x10{sup 4} mol{sup -1} dm{sup 3} s{sup -1}, while the pseudo-first-order rate constant for the subsequent formation of the alcohol (or electroinactive alcoholate) was 1000 s{sup -1}. Kinetically, the electrochemistry is similar to that in acetonitrile or alkaline ethanol. At lower potential sweep rates, a third irreversible reduction occurs which appears to be the reduction of the pyrrolidinium cation as an ion-associated species with the anion products of the initial reductions.

  13. Self-segregated nanostructure in room temperature ionic liquids.

    Science.gov (United States)

    Pontoni, Diego; Haddad, Julia; Di Michiel, Marco; Deutsch, Moshe

    2017-08-29

    The nanosegregated bulk structure, and its evolution with the cation's alkyl length n, are studied by X-ray scattering for an unprecedentedly broad homologous series of a model room-temperature ionic liquid, [CnMIM][NTf2] (n = 4-22). A tri-periodic local structure is found, with the lateral periodicities, dII and dIII independent of n, and a longitudinal one, dI, linearly increasing with n. The results are consistent with a local structure comprising alternating layers of polar headgroups and apolar, interdigitated, partly overlapping, cations' alkyl tails, of an average macroscopic mass density close to that of liquid alkanes. A slope decrease in the linear dI(n) suggests a change from a lower to a higher rate of increase with n of chain overlap for n ≥ 12. The order decay lengths of the layering, and of the lateral chain packing, increase with n, as expected from the increasing van der Waals interaction's domination of the structure. The headgroups' lateral packing decay length decreases with n, due to increasing frustration between the longer lateral periodicity preferred by the headgroups, and the shorter lateral periodicity preferred by the chains. A comparison of the bulk and surface structures highlights the surface's ordering effect, which, however, does not induce here a surface phase different from the bulk, as it does in liquid crystals and liquid alkanes.

  14. Room-temperature short-wavelength infrared Si photodetector

    Science.gov (United States)

    Berencén, Yonder; Prucnal, Slawomir; Liu, Fang; Skorupa, Ilona; Hübner, René; Rebohle, Lars; Zhou, Shengqiang; Schneider, Harald; Helm, Manfred; Skorupa, Wolfgang

    2017-03-01

    The optoelectronic applications of Si are restricted to the visible and near-infrared spectral range due to its 1.12 eV-indirect band gap. Sub-band gap light detection in Si, for instance, has been a long-standing scientific challenge for many decades since most photons with sub-band gap energies pass through Si unabsorbed. This fundamental shortcoming, however, can be overcome by introducing non-equilibrium deep-level dopant concentrations into Si, which results in the formation of an impurity band allowing for strong sub-band gap absorption. Here, we present steady-state room-temperature short-wavelength infrared p-n photodiodes from single-crystalline Si hyperdoped with Se concentrations as high as 9 × 1020 cm‑3, which are introduced by a robust and reliable non-equilibrium processing consisting of ion implantation followed by millisecond-range flash lamp annealing. We provide a detailed description of the material properties, working principle and performance of the photodiodes as well as the main features in the studied wavelength region. This work fundamentally contributes to establish the short-wavelength infrared detection by hyperdoped Si in the forefront of the state-of-the-art of short-IR Si photonics.

  15. Gradient limitations in room temperature and superconducting acceleration structures

    Energy Technology Data Exchange (ETDEWEB)

    Solyak, N.A.; /Fermilab

    2008-10-01

    Accelerating gradient is a key parameter of the accelerating structure in large linac facilities, like future Linear Collider. In room temperature accelerating structures the gradient is limited mostly by breakdown phenomena, caused by high surface electric fields or pulse surface heating. High power processing is a necessary procedure to clean surface and improve the gradient. In the best tested X-band structures the achieved gradient is exceed 100 MV/m in of {approx}200 ns pulses for breakdown rate of {approx} 10{sup -7}. Gradient limit depends on number of factors and no one theory which can explain all sets of experimental results and predict gradient in new accelerating structure. In paper we briefly overview the recent experimental results of breakdown studies, progress in understanding of gradient limitations and scaling laws. Although superconducting rf technology has been adopted throughout the world for ILC, it has frequently been difficult to reach the predicted performance in these structures due to a number of factors: multipactoring, field emission, Q-slope, thermal breakdown. In paper we are discussing all these phenomena and the ways to increase accelerating gradient in SC cavity, which are a part of worldwide R&D program.

  16. Novel Cubic Magnetite Nanoparticle Synthesis Using Room Temperature Ionic Liquid

    Directory of Open Access Journals (Sweden)

    M. Sundrarajan

    2012-01-01

    Full Text Available Room Temperature Ionic liquids are relatively more useful in the synthesis of inorganic nanostructured materials because of their unique properties. To synthesize the iron oxide nanoparticle in simple precipitation method, a novel ionic liquid was used as the greener medium and stabilizing agent namely “1-n-butyl-3-methylimidazolium trifluoromethane sulfonate [BMIM][TfO]”. The crystallinity, chemical structure, morphology and magnetic properties of the synthesized magnetite nanoparticles have been characterized by using X-ray diffraction (XRD, Fourier Transform Infrared (FT-IR, Scanning electron microscopy (SEM, Atomic force microscopy(AFM, Transmission electron microscopy (TEM and Vibrating sample magnetometer (VSM studies. The XRD study is divulge that the synthesized magnetite nanoparticles have inverse spinel face centered cubic structure. The FT-IR vibration peaks show the formation of Fe3O4 nanoparticles, where the vibration peak for Fe-O is deliberately presence at 584 cm-1. The average particle size of the synthesized nanoparticles is found to be 35 nm. Homogeneously dispersed cubic shape with superstructure is found through SEM, AFM and TEM examination studies. The synthesized iron oxide nanoparticles have a high saturation magnetization value of 25 emu/g, which is very much useful for biomedical applications.

  17. Cross-linking of polytetrafluoroethylene during room-temperature irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pugmire, David L [Los Alamos National Laboratory; Wetteland, Chris J [Los Alamos National Laboratory; Duncan, Wanda S [Los Alamos National Laboratory; Lakis, Rollin E [Los Alamos National Laboratory; Schwartz, Daniel S [Los Alamos National Laboratory

    2008-01-01

    Exposure of polytetrafluoroethylene (PTFE) to {alpha}-radiation was investigated to detennine the physical and chemical effects, as well as to compare and contrast the damage mechanisms with other radiation types ({beta}, {gamma}, or thermal neutron). A number of techniques were used to investigate the chemical and physical changes in PTFE after exposure to {alpha}-radiation. These techniques include: Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and fluorescence spectroscopy. Similar to other radiation types at low doses, the primary damage mechanism for the exposure of PTFE to {alpha}-radiation appears to be chain scission. Increased doses result in a change-over of the damage mechanism to cross-linking. This result is not observed for any radiation type other than {alpha} when irradiation is performed at room temperature. Finally, at high doses, PTFE undergoes mass-loss (via smallfluorocarbon species evolution) and defluorination. The amount and type of damage versus sample depth was also investigated. Other types of radiation yield damage at depths on the order of mm to cm into PTFE due to low linear energy transfer (LET) and the correspondingly large penetration depths. By contrast, the {alpha}-radiation employed in this study was shown to only induce damage to a depth of approximately 26 {mu}m, except at very high doses.

  18. Room temperature syntheses of entirely diverse substituted β-fluorofurans.

    Science.gov (United States)

    Li, Yan; Wheeler, Kraig A; Dembinski, Roman

    2012-03-28

    Synthesis of highly substituted 3-fluorofurans is reported. The sequence began with preparation of tert-butyldimethylsilyl alk-1-en-3-yn-1-yl ethers from 1,4-disubstituted alk-3-yn-1-ones. Subsequent fluorination of alkenynyl silyl ethers with Selectfluor gave 2-fluoroalk-3-yn-1-ones in almost quantitative yield. Subsequent 5-endo-dig cyclizations using chlorotriphenylphosphine gold(I)/silver trifluoromethanesulfonate (5/5 mol%), N-bromo- or N-iodosuccinimide and gold(I) chloride/zinc bromide (5/20 mol%), all at room temperature, provided a facile method for the generation of substituted 3-fluoro-, 3-bromo-4-fluoro-, and 3-fluoro-4-iodofurans in good yields. Also, 2,2-difluoroalk-3-yn-1-ones were prepared by fluorination of alk-3-yn-1-ones under organocatalytic conditions. The structures of (Z)-tert-butyldimethylsilyl but-1-en-3-yn-1-yl ether, 3-bromo-4-fluorofuran, and 3-fluoro-4-(phenylethynyl)furan were confirmed by X-ray crystallography.

  19. High Efficiency, Room Temperature Mid-Infrared Semiconductor Laser Development for IR Countermeasures

    Science.gov (United States)

    2009-05-01

    CONTRACT NUMBER EFFICIENCY, ROOM TEMPERATURE MID-INFRARED SEMICONDUCTOR LASER DEVELOPMENT FOR IR COUNTERMEASURES Sb. GRANT NUMBER FA9550-04-1-0433...04-1-0433 Title: (DEPSCOR FY04) High Efficiency, Room Temperature Mid-Infrared Semiconductor Laser Development for IR Countermeasures Principal...AFOSR Final Performance Report, March 2008 Award No.: FA9550-04-1-0433 Title: High Efficiency, Room Temperature Mid-Infrared Semiconductor Laser

  20. Room temperature single-photon detectors for high bit rate quantum key distribution

    Energy Technology Data Exchange (ETDEWEB)

    Comandar, L. C.; Patel, K. A. [Toshiba Research Europe Ltd., 208 Cambridge Science Park, Milton Road, Cambridge CB4 0GZ (United Kingdom); Engineering Department, Cambridge University, 9 J J Thomson Ave., Cambridge CB3 0FA (United Kingdom); Fröhlich, B., E-mail: bernd.frohlich@crl.toshiba.co.uk; Lucamarini, M.; Sharpe, A. W.; Dynes, J. F.; Yuan, Z. L.; Shields, A. J. [Toshiba Research Europe Ltd., 208 Cambridge Science Park, Milton Road, Cambridge CB4 0GZ (United Kingdom); Penty, R. V. [Engineering Department, Cambridge University, 9 J J Thomson Ave., Cambridge CB3 0FA (United Kingdom)

    2014-01-13

    We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.

  1. The design of an embedded system for controlling humidity and temperature room

    Science.gov (United States)

    Dwi Teguh, R.; Didik Eko, S.; Laksono, Pringgo D.; Jamaluddin, Anif

    2016-11-01

    The aim of the system is to design an embedded system for maintenance confortable room. The confortable room was design by controlling temperature (on range 18 - 34 °C) and humidity (on range 40% - 70%.) of room condition. Temperature and humidity of room were maintained using four variable such as lamp for warm, water pump for distributing water vapour, a fan for air circullation and an exhaust-fan for air cleaner. The system was constucted both hardware (humidity sensor, microcontroller, pump, lamp, fan) and software (arduino IDE). The result shows that the system was perfectly performed to control room condition.

  2. Magnetic antiskyrmions above room temperature in tetragonal Heusler materials

    Science.gov (United States)

    Nayak, Ajaya K.; Kumar, Vivek; Ma, Tianping; Werner, Peter; Pippel, Eckhard; Sahoo, Roshnee; Damay, Franoise; Rößler, Ulrich K.; Felser, Claudia; Parkin, Stuart S. P.

    2017-08-01

    . Direct imaging by Lorentz transmission electron microscopy shows field-stabilized antiskyrmion lattices and isolated antiskyrmions from 100 kelvin to well beyond room temperature, and zero-field metastable antiskyrmions at low temperatures. These results enlarge the family of magnetic skyrmions and pave the way to the engineering of complex bespoke designed skyrmionic structures.

  3. Near room temperature ferromagnetism of copper phthalocyanine thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, XueYan, E-mail: xueyanadeline@163.com; Zheng, JianBang; Chen, Lei; Qiao, Kai; Xu, JiaWei; Cao, ChongDe

    2015-11-30

    Highlights: • The α-CuPc films without and with light Ni-doping were characterized by X-ray photoelectron spectroscopy to confirm the absence of other ferromagnetic impurities. • The α-CuPc film exhibited ferromagnetic hysteresis with saturation magnetization of ∼6.77 emu/cm{sup 3} and coercivity of ∼96 Oe at 280 K, while that of the Ni-doped α-CuPc film are ∼0.69 emu/cm{sup 3} and ∼113 Oe, respectively. • Through the density functional theory calculations, the origin of the ferromagnetism arise from Cu 3d states and N 2s2p electronic spin polarization, as well as p–d exchange coupling interactions, and spin-unbalanced electronic structure of C 2p induced by the π–π interactions. - Abstract: We reported near room temperature ferromagnetism of α-CuPc films without and with light Ni-doping. Two samples were characterized by X-ray photoelectron spectroscopy (XPS) to confirm the absence of other ferromagnetic impurities. The α-CuPc film exhibited ferromagnetic hysteresis with saturation magnetization of ∼6.77 emu/cm{sup 3} and coercivity of ∼96 Oe at 280 K, while that of the Ni-doped α-CuPc film are ∼0.69 emu/cm{sup 3} and ∼113 Oe, respectively. Through the density functional theory (DFT) calculations, the origin of the ferromagnetism arise from Cu 3d states and N 2s2p electronic spin polarization, as well as p-d exchange coupling interactions, and spin-unbalanced electronic structure of C 2p induced by the π–π interactions.

  4. Room-temperature macromolecular serial crystallography using synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Francesco Stellato

    2014-07-01

    Full Text Available A new approach for collecting data from many hundreds of thousands of microcrystals using X-ray pulses from a free-electron laser has recently been developed. Referred to as serial crystallography, diffraction patterns are recorded at a constant rate as a suspension of protein crystals flows across the path of an X-ray beam. Events that by chance contain single-crystal diffraction patterns are retained, then indexed and merged to form a three-dimensional set of reflection intensities for structure determination. This approach relies upon several innovations: an intense X-ray beam; a fast detector system; a means to rapidly flow a suspension of crystals across the X-ray beam; and the computational infrastructure to process the large volume of data. Originally conceived for radiation-damage-free measurements with ultrafast X-ray pulses, the same methods can be employed with synchrotron radiation. As in powder diffraction, the averaging of thousands of observations per Bragg peak may improve the ratio of signal to noise of low-dose exposures. Here, it is shown that this paradigm can be implemented for room-temperature data collection using synchrotron radiation and exposure times of less than 3 ms. Using lysozyme microcrystals as a model system, over 40 000 single-crystal diffraction patterns were obtained and merged to produce a structural model that could be refined to 2.1 Å resolution. The resulting electron density is in excellent agreement with that obtained using standard X-ray data collection techniques. With further improvements the method is well suited for even shorter exposures at future and upgraded synchrotron radiation facilities that may deliver beams with 1000 times higher brightness than they currently produce.

  5. Thermomechanical analysis of Natural Rubber behaviour stressed at room temperature.

    Science.gov (United States)

    Caborgan, R.; Muracciole, J. M.; Wattrisse, B.; Chrysochoos, A.

    2010-06-01

    Owing to their high molecular mobility, stressed rubber chains can easily change their conformations and get orientated. This phenomena leads to so high reversible draw ratio that this behaviour is called rubber elasticity [1-3]. The analogy with ideal gases leads to an internal energy independent of elongation, the stress being attributed to a so-called configuration entropy. However, this analysis cannot take thermal expansion into account and moreover prohibits predicting standard thermo-elastic effect noticed at small elongations and the thermoelastic inversion effects [4]. This paper aims at : observing and quantifying dissipative and coupling effects associated with deformation energy, generated when Natural Rubber is stretched. re-examine the thermomechanical behaviour model of rubberlike materials, under the generalised standard material concept. From an experimental viewpoint, energy balance is created using infrared and quantitative imaging techniques. Digital Image Correlation (DIC) provides in-the-plane displacement fields and, after derivation, strain and strain-rate fields. We have used those techniques to evidence the thermoelastic inversion effect as shown on Figure 1 where different weights have been fixed to warmed specimen and we monitored the sample deformation while it recovers room temperature. But we have also used those techniques to perform energy balance : analysis of the mechanical equilibrium allows estimates of the stress pattern and computation of deformation energy rates under a plane stress hypothesis [5]. Infrared Thermography (IRT) gives the surface temperature of the sample. To estimate the distribution of heat sources, image processing with a local heat equation and a minimal set of approximation functions (image filtering) was used. The time courses of deformation energy and heat associated with cyclic process are plotted in Figure 2. The time derivatives of both forms of energy are approximately similar. This is consistent with

  6. Thermomechanical analysis of Natural Rubber behaviour stressed at room temperature.

    Directory of Open Access Journals (Sweden)

    Chrysochoos A.

    2010-06-01

    Full Text Available Owing to their high molecular mobility, stressed rubber chains can easily change their conformations and get orientated. This phenomena leads to so high reversible draw ratio that this behaviour is called rubber elasticity [1-3]. The analogy with ideal gases leads to an internal energy independent of elongation, the stress being attributed to a so-called configuration entropy. However, this analysis cannot take thermal expansion into account and moreover prohibits predicting standard thermo-elastic effect noticed at small elongations and the thermoelastic inversion effects [4]. This paper aims at : observing and quantifying dissipative and coupling effects associated with deformation energy, generated when Natural Rubber is stretched. re-examine the thermomechanical behaviour model of rubberlike materials, under the generalised standard material concept. From an experimental viewpoint, energy balance is created using infrared and quantitative imaging techniques. Digital Image Correlation (DIC provides in-the-plane displacement fields and, after derivation, strain and strain-rate fields. We have used those techniques to evidence the thermoelastic inversion effect as shown on Figure 1 where different weights have been fixed to warmed specimen and we monitored the sample deformation while it recovers room temperature. But we have also used those techniques to perform energy balance : analysis of the mechanical equilibrium allows estimates of the stress pattern and computation of deformation energy rates under a plane stress hypothesis [5]. Infrared Thermography (IRT gives the surface temperature of the sample. To estimate the distribution of heat sources, image processing with a local heat equation and a minimal set of approximation functions (image filtering was used. The time courses of deformation energy and heat associated with cyclic process are plotted in Figure 2. The time derivatives of both forms of energy are approximately similar. This

  7. Robust isothermal electric control of exchange bias at room temperature

    Science.gov (United States)

    Binek, Christian

    2011-03-01

    Voltage-controlled spintronics is of particular importance to continue progress in information technology through reduced power consumption, enhanced processing speed, integration density, and functionality in comparison with present day CMOS electronics. Almost all existing and prototypical solid-state spintronic devices rely on tailored interface magnetism, enabling spin-selective transmission or scattering of electrons. Controlling magnetism at thin-film interfaces, preferably by purely electrical means, is a key challenge to better spintronics. Currently, most attempts to electrically control magnetism focus on potentially large magnetoelectric effects of multiferroics. We report on our interest in magnetoelectric Cr 2 O3 (chromia). Robust isothermal electric control of exchange bias is achieved at room temperature in perpendicular anisotropic Cr 2 O3 (0001)/CoPd exchange bias heterostructures. This discovery promises significant implications for potential spintronics. From the perspective of basic science, our finding serves as macroscopic evidence for roughness-insensitive and electrically controllable equilibrium boundary magnetization in magnetoelectric antiferromagnets. The latter evolves at chromia (0001) surfaces and interfaces when chromia is in one of its two degenerate antiferromagnetic single domain states selected via magnetoelectric annealing. Theoretical insight into the boundary magnetization and its role in electrically controlled exchange bias is gained from first-principles calculations and general symmetry arguments. Measurements of spin-resolved ultraviolet photoemission, magnetometry at Cr 2 O3 (0001) surfaces, and detailed investigations of the unique exchange bias properties of Cr 2 O3 (0001)/CoPd including its electric controllability provide macroscopically averaged information about the boundary magnetization of chromia. Laterally resolved X-ray PEEM and temperature dependent MFM reveal detailed microscopic information of the chromia

  8. Structure of photosystem II and substrate binding at room temperature

    Science.gov (United States)

    Gul, Sheraz; Fuller, Franklin; Koroidov, Sergey; Brewster, Aaron S.; Tran, Rosalie; Alonso-Mori, Roberto; Kroll, Thomas; Michels-Clark, Tara; Laksmono, Hartawan; Sierra, Raymond G.; Stan, Claudiu A.; Hussein, Rana; Zhang, Miao; Douthit, Lacey; Kubin, Markus; de Lichtenberg, Casper; Long Vo, Pham; Nilsson, Håkan; Cheah, Mun Hon; Shevela, Dmitriy; Saracini, Claudio; Bean, Mackenzie A.; Seuffert, Ina; Sokaras, Dimosthenis; Weng, Tsu-Chien; Pastor, Ernest; Weninger, Clemens; Fransson, Thomas; Lassalle, Louise; Bräuer, Philipp; Aller, Pierre; Docker, Peter T.; Andi, Babak; Orville, Allen M.; Glownia, James M.; Nelson, Silke; Sikorski, Marcin; Zhu, Diling; Hunter, Mark S.; Lane, Thomas J.; Aquila, Andy; Koglin, Jason E.; Robinson, Joseph; Liang, Mengning; Boutet, Sébastien; Lyubimov, Artem Y.; Uervirojnangkoorn, Monarin; Moriarty, Nigel W.; Liebschner, Dorothee; Afonine, Pavel V.; Waterman, David G.; Evans, Gwyndaf; Wernet, Philippe; Dobbek, Holger; Weis, William I.; Brunger, Axel T.; Zwart, Petrus H.; Adams, Paul D.; Zouni, Athina; Messinger, Johannes; Bergmann, Uwe; Sauter, Nicholas K.; Kern, Jan; Yachandra, Vittal K.; Yano, Junko

    2016-01-01

    Light-induced oxidation of water by photosystem II (PS II) in plants, algae and cyanobacteria has generated most of the dioxygen in the atmosphere. PS II, a membrane-bound multi-subunit pigment-protein complex, couples the one-electron photochemistry at the reaction center with the four-electron redox chemistry of water oxidation at the Mn4CaO5 cluster in the oxygen-evolving complex (OEC) (Fig. 1a, Extended Data Fig. 1). Under illumination, the OEC cycles through five intermediate S-states (S0 to S4)1, where S1 is the dark stable state and S3 is the last semi-stable state before O-O bond formation and O2 evolution2,3. A detailed understanding of the O-O bond formation mechanism remains a challenge, and elucidating the structures of the OEC in the different S-states, as well as the binding of the two substrate waters to the catalytic site4-6, is a prerequisite for this purpose. Here we report the use of femtosecond pulses from an X-ray free electron laser (XFEL) to obtain damage free, room temperature (RT) structures of dark-adapted (S1), two-flash illuminated (2F; S3-enriched), and ammonia-bound two-flash illuminated (2F-NH3; S3-enriched) PS II. Although the recent 1.95 Å structure of PS II7 at cryogenic temperature using an XFEL provided a damage-free view of the S1 state, RT measurements are required to study the structural landscape of proteins under functional conditions8,9, and also for in situ advancement of the S-states. To investigate the water-binding site(s), ammonia, a water analog, has been used as a marker, as it binds to the Mn4CaO5 cluster in the S2 and S3 states10. Since the ammonia-bound OEC is active, the ammonia-binding Mn site is not a substrate water site10-13. Thus, this approach, together with a comparison of the native dark and 2F states, is used to discriminate between proposed O-O bond formation mechanisms. PMID:27871088

  9. CdZnTe room-temperature semiconductor operation in liquid scintillator

    CERN Document Server

    Stewart, D Y

    2008-01-01

    We demonstrate the first operation of CdZnTe room-temperature detectors in a liquid scintillator environment. This work follows conceptually the Heusser-type detector method of operating HPGe detectors in liquid nitrogen and liquid argon but instead for a far more practical room-temperature ensemble with the aim of achieving ultra-low background levels for radiation detection.

  10. Realization of tin freezing point using a loop heat pipe-based hydraulic temperature control technique

    Science.gov (United States)

    Joung, Wukchul; Gam, Kee Sool; Kim, Yong-Gyoo

    2015-10-01

    In this work, the freezing point of tin (Sn FP) was realized by inside nucleation where the supercooling of tin and the reheating of the sample after the nucleation were achieved without extracting the cell from an isothermal apparatus. To this end, a novel hydraulic temperature control technique, which was based on the thermo-hydraulic characteristics of a pressure-controlled loop heat pipe (LHP), was employed to provide a slow cooling of the sample for deep supercooling and fast reheating after nucleation to minimize the amount of initial freeze of the sample. The required temperature controls were achieved by the active pressure control of a control gas inside the compensation chamber of the pressure-controlled LHP, and slow cooling at  -0.05 K min-1 for the deep supercooling of tin and fast heating at 2 K min-1 for reheating the sample after nucleation was attained. Based on this hydraulic temperature control technique, the nucleation of tin was realized at supercooling of around 19 K, and a satisfactorily fast reheating of the sample to the plateau-producing temperature (i.e. 0.5 K below the Sn FP) was achieved without any temperature overshoots of the isothermal region. The inside-nucleated Sn FP showed many desirable features compared to the Sn FP realized by the conventional outside nucleation method. The longer freezing plateaus and the better immersion characteristics of the Sn FP were obtained by inside nucleation, and the measured freezing temperature of the inside-nucleated Sn FP was as much as 0.37 mK higher than the outside-nucleated Sn FP with an expanded uncertainty of 0.19 mK. Details on the experiment are provided and explanations for the observed differences are discussed.

  11. High energy sodium based room temperature flow batteries

    Science.gov (United States)

    Shamie, Jack

    As novel energy sources such as solar, wind and tidal energies are explored it becomes necessary to build energy storage facilities to load level the intermittent nature of these energy sources. Energy storage is achieved by converting electrical energy into another form of energy. Batteries have many properties that are attractive for energy storage including high energy and power. Among many different types of batteries, redox flow batteries (RFBs) offer many advantages. Unlike conventional batteries, RFBs store energy in a liquid medium rather than solid active materials. This method of storage allows for the separation of energy and power unlike conventional batteries. Additionally flow batteries may have long lifetimes because there is no expansion or contraction of electrodes. A major disadvantage of RFB's is its lower energy density when compared to traditional batteries. In this Thesis, a novel hybrid Na-based redox flow battery (HNFB) is explored, which utilizes a room temperature molten sodium based anode, a sodium ion conducting solid electrolyte and liquid catholytes. The sodium electrode leads to high voltages and energy and allows for the possibility of multi-electron transfer per molecule. Vanadium acetylacetonate (acac) and TEMPO have been investigated for their use as catholytes. In the vanadium system, 2 electrons transfers per vanadium atom were found leading to a doubling of capacity. In addition, degradation of the charged state was found to be reversible within the voltage range of the cell. Contamination by water leads to the formation of vanadyl acetylacetonate. Although it is believed that vanadyl complex need to be taken to low voltages to be reduced back to vanadium acac, a new mechanism is shown that begins at higher voltages (2.1V). Vanadyl complexes react with excess ligand and protons to reform the vanadium complex. During this reaction, water is reformed leading to the continuous cycle in which vanadyl is formed and then reduced back

  12. Design and Realization of Doctor's Workstation for Hemodialysis Room%血透室医生工作站的设计与实现

    Institute of Scientific and Technical Information of China (English)

    王志勇; 郭志勇; 吴灏

    2012-01-01

    目的 设计并实现血透室医生工作站,解决血透室医生诊疗工作中存在的管理问题.方法 分析血透室医生诊疗工作存在的主要问题,提出系统设计的基本原则,建立系统的基本框架和主要功能,并给出了系统扩展方面的考虑.结果 血透室医生工作站优化了血透室的工作模式,解决了血透室传统诊疗模式的局限性.结论 血透室医生工作站的设计与实现,能有效提高血透室的工作效率和医疗质量.%Objective To design and realize a doctor's workstation for hemodialysis room, thus to solve the management problems of the diagnosis and treatment in hemodialysis room. Methods Analyzed the main problems of hemodialysis room, put forward the basic principles of system design, built the basic frame and main function of the system, and introduced the system expansion considerations. Results The hemodialysis room doctor workstation was established, the work mode of hemodialysis room was optimized, and the limitation of traditional diagnosis and treatment was solved. Conclusion The doctor's workstation for hemodialysis room can effectively improve the working efficiency and medical quality of hemodialysis room.

  13. Ordered iron aluminide alloys having an improved room-temperature ductility and method thereof

    Science.gov (United States)

    Sikka, Vinod K.

    1992-01-01

    A process is disclosed for improving the room temperature ductility and strength of iron aluminide intermetallic alloys. The process involves thermomechanically working an iron aluminide alloy by means which produce an elongated grain structure. The worked alloy is then heated at a temperature in the range of about 650.degree. C. to about 800.degree. C. to produce a B2-type crystal structure. The alloy is rapidly cooled in a moisture free atmosphere to retain the B2-type crystal structure at room temperature, thus providing an alloy having improved room temperature ductility and strength.

  14. Wireless Passive Temperature Sensor Realized on Multilayer HTCC Tapes for Harsh Environment

    Directory of Open Access Journals (Sweden)

    Qiulin Tan

    2015-01-01

    Full Text Available A wireless passive temperature sensor is designed on the basis of a resonant circuit, fabricated on multilayer high temperature cofired ceramic (HTCC tapes, and measured with an antenna in the wireless coupling way. Alumina ceramic used as the substrate of the sensor is fabricated by lamination and sintering techniques, and the passive resonant circuit composed of a planar spiral inductor and a parallel plate capacitor is printed and formed on the substrate by screen-printing and postfiring processes. Since the permittivity of the ceramic becomes higher as temperature rises, the resonant frequency of the sensor decreases due to the increasing capacitance of the circuit. Measurements on the input impedance versus the resonant frequency of the sensor are achieved based on the principle, and discussions are made according to the exacted relative permittivity of the ceramic and quality factor (Q of the sensor within the temperature range from 19°C (room temperature to 900°C. The results show that the sensor demonstrates good high-temperature characteristics and wide temperature range. The average sensitivity of the sensor with good repeatability and reliability is up to 5.22 KHz/°C. It can be applied to detect high temperature in harsh environment.

  15. Electronic spin transport and spin precession in single graphene layers at room temperature.

    Science.gov (United States)

    Tombros, Nikolaos; Jozsa, Csaba; Popinciuc, Mihaita; Jonkman, Harry T; van Wees, Bart J

    2007-08-02

    Electronic transport in single or a few layers of graphene is the subject of intense interest at present. The specific band structure of graphene, with its unique valley structure and Dirac neutrality point separating hole states from electron states, has led to the observation of new electronic transport phenomena such as anomalously quantized Hall effects, absence of weak localization and the existence of a minimum conductivity. In addition to dissipative transport, supercurrent transport has also been observed. Graphene might also be a promising material for spintronics and related applications, such as the realization of spin qubits, owing to the low intrinsic spin orbit interaction, as well as the low hyperfine interaction of the electron spins with the carbon nuclei. Here we report the observation of spin transport, as well as Larmor spin precession, over micrometre-scale distances in single graphene layers. The 'non-local' spin valve geometry was used in these experiments, employing four-terminal contact geometries with ferromagnetic cobalt electrodes making contact with the graphene sheet through a thin oxide layer. We observe clear bipolar (changing from positive to negative sign) spin signals that reflect the magnetization direction of all four electrodes, indicating that spin coherence extends underneath all of the contacts. No significant changes in the spin signals occur between 4.2 K, 77 K and room temperature. We extract a spin relaxation length between 1.5 and 2 mum at room temperature, only weakly dependent on charge density. The spin polarization of the ferromagnetic contacts is calculated from the measurements to be around ten per cent.

  16. Room temperature coherent spin alignment of silicon vacancies in 4H- and 6H-SiC

    OpenAIRE

    Soltamov, Victor A.; Soltamova, Alexandra A.; Proskuryakov, Ivan I.; Baranov, Pavel G.

    2012-01-01

    We report the realization of the optically induced inverse population of the ground-state spin sublevels of the silicon vacancies ($V_{\\mathrm{Si}}$) in silicon carbide (SiC) at room temperature. The data show that the probed silicon vacancy spin ensemble can be prepared in a coherent superposition of the spin states. Rabi nutations persist for more than 80 $\\mu$s. Two opposite schemes of the optical alignment of the populations between the ground-state spin sublevels of the silicon vacancy u...

  17. Room-Temperature Large and Reversible Modulation of Photoluminescence by in Situ Electric Field in Ergodic Relaxor Ferroelectrics.

    Science.gov (United States)

    Sun, Hailing; Wu, Xiao; Peng, Deng Feng; Kwok, K W

    2017-10-04

    Ferroelectric oxides with luminescent ions hold great promise in future optoelectronic devices because of their unique photoluminescence and inherent ferroelectric properties. Intriguingly, the photoluminescence performance of ferroelectric ceramics could be modulated by an external electric field. However, researchers face a current challenge of the diminutive extent and degree of reversibility of the field-driven modification that hinder their use in room-temperature practical applications. Within the scope of current contribution in rare-earth-doped bismuth sodium titanate relaxors, the most important information to be noted is the shifting of the depolarization temperature toward room temperature and the resulting considerable enhancement in ergodicity, as evidenced by the dielectric properties, polarization, and strain hysteresis, as well as the in situ Raman/X-ray diffraction studies. After the introduction of 1 mol % Eu, the induced composition and charge disorders disrupt the original long-range ferroelectric macrodomains into randomly dynamic and weakly correlated polar nanoregions, which facilitates a reversible transformation between polar nanoregions and unstable ferroelectric state under an electric field, engendering a large strain. By virtue of this, both the extent and degree of reversibility of photoluminescence modulation are enhanced (∼60%) considerably, and room-temperature in situ tunable photoluminescence response is then achieved under electric field. These should be helpful for the realization of regulating the physical couplings (photoluminescent-ferroelectrics) in multifunctional inorganic ferroelectrics with a high ergodic state by reversibly tuning the structural symmetry.

  18. Oxygen Vacancy Induced Room-Temperature Metal-Insulator Transition in Nickelate Films and Its Potential Application in Photovoltaics.

    Science.gov (United States)

    Wang, Le; Dash, Sibashisa; Chang, Lei; You, Lu; Feng, Yaqing; He, Xu; Jin, Kui-juan; Zhou, Yang; Ong, Hock Guan; Ren, Peng; Wang, Shiwei; Chen, Lang; Wang, Junling

    2016-04-20

    Oxygen vacancy is intrinsically coupled with magnetic, electronic, and transport properties of transition-metal oxide materials and directly determines their multifunctionality. Here, we demonstrate reversible control of oxygen content by postannealing at temperature lower than 300 °C and realize the reversible metal-insulator transition in epitaxial NdNiO₃ films. Importantly, over 6 orders of magnitude in the resistance modulation and a large change in optical bandgap are demonstrated at room temperature without destroying the parent framework and changing the p-type conductive mechanism. Further study revealed that oxygen vacancies stabilized the insulating phase at room temperature is universal for perovskite nickelate films. Acting as electron donors, oxygen vacancies not only stabilize the insulating phase at room temperature, but also induce a large magnetization of ∼50 emu/cm³ due to the formation of strongly correlated Ni²⁺ t(2g)⁶e(g)² states. The bandgap opening is an order of magnitude larger than that of the thermally driven metal-insulator transition and continuously tunable. Potential application of the newly found insulating phase in photovoltaics has been demonstrated in the nickelate-based heterojunctions. Our discovery opens up new possibilities for strongly correlated perovskite nickelates.

  19. Consistency of the National Realization of Dew-Point Temperature Using Standard Humidity Generators

    Science.gov (United States)

    Benyon, R.; Vicente, T.

    2012-09-01

    The comparison of two high-range standard humidity generators used by Instituto Nacional de Técnica Aeroespacial to realize dew-point temperature in the range from -10 °C to +95 °C has been performed using state-of-the art transfer standards and measurement procedures, over their overlapping range from -10 °C to +75 °C. The aim of this study is to investigate the level of agreement between the two generators, to determine any bias, and to quantify the level of consistency of the two realizations. The measurement procedures adopted to minimize the effect of the influence factors due to the transfer standards are described, and the results are discussed in the context of the declared calibration and measurement capabilities (CMCs).

  20. New insights into designing metallacarborane based room temperature hydrogen storage media.

    Science.gov (United States)

    Bora, Pankaj Lochan; Singh, Abhishek K

    2013-10-28

    Metallacarboranes are promising towards realizing room temperature hydrogen storage media because of the presence of both transition metal and carbon atoms. In metallacarborane clusters, the transition metal adsorbs hydrogen molecules and carbon can link these clusters to form metal organic framework, which can serve as a complete storage medium. Using first principles density functional calculations, we chalk out the underlying principles of designing an efficient metallacarborane based hydrogen storage media. The storage capacity of hydrogen depends upon the number of available transition metal d-orbitals, number of carbons, and dopant atoms in the cluster. These factors control the amount of charge transfer from metal to the cluster, thereby affecting the number of adsorbed hydrogen molecules. This correlation between the charge transfer and storage capacity is general in nature, and can be applied to designing efficient hydrogen storage systems. Following this strategy, a search for the best metallacarborane was carried out in which Sc based monocarborane was found to be the most promising H2 sorbent material with a 9 wt.% of reversible storage at ambient pressure and temperature.

  1. Substrate Temperature Effects on Room Temperature Sensing Properties of Nanostructured ZnO Thin Films.

    Science.gov (United States)

    Reddy, Jonnala Rakesh; Mani, Ganesh Kumar; Shankar, Prabakaran; Rayappan, John Bosco Balaguru

    2016-01-01

    Zinc oxide (ZnO) thin films were deposited on glass substrates using chemical spray pyrolysis technique at different substrate temperatures such as 523, 623 and 723 K. X-ray diffraction (XRD) patterns confirmed the formation of polycrystalline films with hexagonal wurtzite crystal structure and revealed the change in preferential orientation of the crystal planes. Scanning electron micrographs showed the formation of uniformly distributed spherical shaped grains at low deposition temperature and pebbles like structure at the higher temperature. Transmittance of 85% was observed for the film deposited at 723 K. The band gap of the films was found to be increased from 3.15 to 3.23 eV with a rise in deposition temperature. The electrical conductivity of the films was found to be improved with an increase in substrate temperature. Surface of ZnO thin films deposited at 523 K, 623 K and 723 K were found to be hydrophobic with the contact angles of 92°, 105° and 128° respectively. The room temperature gas sensing characteristics of all the films were studied and found that the film deposited at 623 K showed a better response towards ammonia vapour.

  2. Optical Diode Effect at Spin-Wave Excitations of the Room-Temperature Multiferroic BiFeO3

    Science.gov (United States)

    Kézsmárki, I.; Nagel, U.; Bordács, S.; Fishman, R. S.; Lee, J. H.; Yi, Hee Taek; Cheong, S.-W.; Rõõm, T.

    2015-09-01

    Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO3 over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. These findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.

  3. Optical Diode Effect at Spin-Wave Excitations of the Room-Temperature Multiferroic BiFeO_{3}.

    Science.gov (United States)

    Kézsmárki, I; Nagel, U; Bordács, S; Fishman, R S; Lee, J H; Yi, Hee Taek; Cheong, S-W; Rõõm, T

    2015-09-18

    Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO_{3} over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. These findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.

  4. Semiconductor terahertz technology devices and systems at room temperature operation

    CERN Document Server

    Carpintero, G; Hartnagel, H; Preu, S; Raisanen, A

    2015-01-01

    Key advances in Semiconductor Terahertz (THz) Technology now promises important new applications enabling scientists and engineers to overcome the challenges of accessing the so-called "terahertz gap".  This pioneering reference explains the fundamental methods and surveys innovative techniques in the generation, detection and processing of THz waves with solid-state devices, as well as illustrating their potential applications in security and telecommunications, among other fields. With contributions from leading experts, Semiconductor Terahertz Technology: Devices and Systems at Room Tempe

  5. Certification of NIST Room Temperature Low-Energy and High-Energy Charpy Verification Specimens

    OpenAIRE

    Lucon, Enrico; McCowan, Chris N.; Santoyo, Ray L.

    2015-01-01

    The possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of −40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots ...

  6. Existence of the multiferroic property at room temperature in Ti doped CoFeO

    Science.gov (United States)

    Dwivedi, G. D.; Joshi, Amish G.; Kevin, H.; Shahi, P.; Kumar, A.; Ghosh, A. K.; Yang, H. D.; Chatterjee, Sandip

    2012-03-01

    The appearance of ferroelectricity has been observed in magnetically ordered Co(Fe1-xTix)2O4 at room temperature. Magnetization and dielectric constant is found to increase with Ti doping. It is observed from an X-ray Photoemission Spectroscopy study that Ti goes to the octahedral site with (+4) ionic state. An M-H hysteresis curve at room temperature shows the ferrimagnetic ordering and a P-E loop at room temperature clearly indicates the existence of ferroelectricity.

  7. Pentacene on Ni(111): room-temperature molecular packing and temperature-activated conversion to graphene

    Science.gov (United States)

    Dinca, L. E.; de Marchi, F.; MacLeod, J. M.; Lipton-Duffin, J.; Gatti, R.; Ma, D.; Perepichka, D. F.; Rosei, F.

    2015-02-01

    We investigate, using scanning tunnelling microscopy, the adsorption of pentacene on Ni(111) at room temperature and the behaviour of these monolayer films with annealing up to 700 °C. We observe the conversion of pentacene into graphene, which begins from as low as 220 °C with the coalescence of pentacene molecules into large planar aggregates. Then, by annealing at 350 °C for 20 minutes, these aggregates expand into irregular domains of graphene tens of nanometers in size. On surfaces where graphene and nickel carbide coexist, pentacene shows preferential adsorption on the nickel carbide phase. The same pentacene to graphene transformation was also achieved on Cu(111), but at a higher activation temperature, producing large graphene domains that exhibit a range of moiré superlattice periodicities.We investigate, using scanning tunnelling microscopy, the adsorption of pentacene on Ni(111) at room temperature and the behaviour of these monolayer films with annealing up to 700 °C. We observe the conversion of pentacene into graphene, which begins from as low as 220 °C with the coalescence of pentacene molecules into large planar aggregates. Then, by annealing at 350 °C for 20 minutes, these aggregates expand into irregular domains of graphene tens of nanometers in size. On surfaces where graphene and nickel carbide coexist, pentacene shows preferential adsorption on the nickel carbide phase. The same pentacene to graphene transformation was also achieved on Cu(111), but at a higher activation temperature, producing large graphene domains that exhibit a range of moiré superlattice periodicities. Electronic supplementary information (ESI) available: Summary of used growth methods for graphene/Ni(111), STM images of pentacene/Ni(111), graphitic structures on Ni(111), pentacene adsorbed on carbide, DFT calculations of pentacene/Ni(111) - the adsorption sites. See DOI: 10.1039/c4nr07057g

  8. Microstructure and room temperature mechanical properties of mullite fibers after heat-treatment at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi; Cheng, Haifeng, E-mail: chfcfc@163.com; Liu, Haitao; Wang, Jun

    2013-08-20

    The composition and microstructure of Nitivy ALF 2880D fibers after heat-treatment at elevated temperatures are investigated by XRD, FT-IR, SEM and TEM analyses. Tensile properties of as-received and heat-treated fiber bundles have been studied. The results show that as-received fibers consist of γ-Al{sub 2}O{sub 3}, amorphous silica, and a little boron oxide. During heat-treatment process, boron oxide firstly melts and flows, resulting in large amount of liquid ravines, and then volatilizes, leaving several holes on fiber surface. Reaction between γ-Al{sub 2}O{sub 3} and amorphous silica begins when heat-treated temperature is above 1100 °C, and completes at 1300 °C. As heat-treated temperature increases from 1100 °C to 1400 °C, grain growth of mullite starts and leads to the reduction of room temperature tensile strength of fibers. Tensile strength of fibers stays stable when heat-treated temperature is below 1200 °C, while the strength retention of fibers sharply decreased to 50% after heat-treatment at 1300 °C.

  9. Realization of High-temperature Superconductivity in Nano-carbon Materials and Its Application

    Science.gov (United States)

    2015-07-13

    hottest topics in condensed matter physics and also for application to zero- emission energy system. In particular, carbon-based superconductors have...nano- carbon materials and its application II 5a. CONTRACT NUMBER FA2386-13-1-4059 5b. GRANT NUMBER Grant 13RSZ067_134059 5c. PROGRAM ELEMENT...for AOARD Grant F A2386-13- l-4059 "Realization of high-temperature superconductivity in nano-carbon materials and its application " Date: 07/13

  10. Observation of Various and Spontaneous Magnetic Skyrmionic Bubbles at Room Temperature in a Frustrated Kagome Magnet with Uniaxial Magnetic Anisotropy

    KAUST Repository

    Hou, Zhipeng

    2017-06-07

    The quest for materials hosting topologically protected skyrmionic spin textures continues to be fueled by the promise of novel devices. Although many materials have demonstrated the existence of such spin textures, major challenges remain to be addressed before devices based on magnetic skyrmions can be realized. For example, being able to create and manipulate skyrmionic spin textures at room temperature is of great importance for further technological applications because they can adapt to various external stimuli acting as information carriers in spintronic devices. Here, the first observation of skyrmionic magnetic bubbles with variable topological spin textures formed at room temperature in a frustrated kagome Fe3 Sn2 magnet with uniaxial magnetic anisotropy is reported. The magnetization dynamics are investigated using in situ Lorentz transmission electron microscopy, revealing that the transformation between different magnetic bubbles and domains is via the motion of Bloch lines driven by an applied external magnetic field. These results demonstrate that Fe3 Sn2 facilitates a unique magnetic control of topological spin textures at room temperature, making it a promising candidate for further skyrmion-based spintronic devices.

  11. THE POLYMERIZATION OF ROOM TEMPERATURE CURING EPOXY RESINS

    Science.gov (United States)

    EPOXY RESINS , *PLASTICS, *POLYMERIZATION, AGING (PHYSIOLOGY), CHEMICAL BONDS, ELECTRICAL PROPERTIES, EMBEDDING SUBSTANCES, MONITORS, POLYMERS, RESISTANCE (ELECTRICAL), STORAGE, STRUCTURES, TEMPERATURE, TEST METHODS, VOLUME

  12. High stereoselective cyclopropanation reaction of 3-acylcoumarins with -bromoketones at room temperature

    Indian Academy of Sciences (India)

    Qin Zhao; Min Chen; Hao-Hao Hui; De-Bing She; Ming-Yu Yang; Guo-sheng huang

    2008-07-01

    Reaction of 3-acylcoumarins with -bromoketones in the presence of a base give the cyclopropane derivatives in good stereoselectivity and moderate yield. The reaction was carried out at room temperature in mixed solvents without exclusion of moisture or air.

  13. Room-temperature single-photon sources based on nanocrystal fluorescence in photonic/plasmonic nanostructures

    Science.gov (United States)

    Lukishova, S. G.; Winkler, J. M.; Bissell, L. J.; Mihaylova, D.; Liapis, Andreas C.; Shi, Z.; Goldberg, D.; Menon, V. M.; Boyd, R. W.; Chen, G.; Prasad, P.

    2014-10-01

    Results are presented here towards robust room-temperature SPSs based on fluorescence in nanocrystals: colloidal quantum dots, color-center diamonds and doped with trivalent rare-earth ions (TR3+). We used cholesteric chiral photonic bandgap and Bragg-reflector microcavities for single emitter fluorescence enhancement. We also developed plasmonic bowtie nanoantennas and 2D-Si-photonic bandgap microcavities. The paper also provides short outlines of other technologies for room-temperature single-photon sources.

  14. Temperature distribution in Risø Flexhouse Room 3 with different heating control principles

    DEFF Research Database (Denmark)

    Simone, Angela; Rode, Carsten

    2009-01-01

    in winter and spring 2009 to study the distribution of local temperatures in the room – particularly with the purpose to compare with the temperature measured and logged by the heating control sensor which was already installed in the room. The measured data shall be used together with mathematical models...... to predict the overall dynamic thermal properties of the building. The project is part of a wider complex of projects on predicting the electricity and heating energy consumption in dwellings....

  15. Photodetector development at Fraunhofer IAF: From LWIR to SWIR operating from cryogenic close to room temperature

    Science.gov (United States)

    Daumer, V.; Gramich, V.; Müller, R.; Schmidt, J.; Rutz, F.; Stadelmann, T.; Wörl, A.; Rehm, R.

    2017-02-01

    Photodetectors in the non-visible region of the electromagnetic spectrum are essential for security, defense and space science as well as industrial and scientific applications. The research activities at Fraunhofer IAF cover a broad range in the infrared (IR) regime. Whereas short-wavelength IR (SWIR, <1.7 μm) detectors are realized by InGaAs/InP structures, InAs/GaSb type-II superlattice (T2SL) infrared detectors are developed for the spectral bands from mid- (MWIR, 3-5 μm) to long-wavelength IR (LWIR, 8-12 μm). We report on the extension of the superlattice empirical pseudopotential method (SEPM) to 300 K for the design of LWIR heterostructures for operation near room temperature. Recently, we have also adapted heterostructure concepts to our well established bi-spectral T2SL MWIR detector resulting in a dark current density below 2 × 10-9 A/cm2 for a cut-off wavelength close to 5 μm. Finally, we present first results obtained with a gated viewing system based on our InGaAs/InAlAs/InP avalanche photodiode arrays.

  16. Simple room-temperature preparation of high-yield large-area graphene oxide.

    Science.gov (United States)

    Huang, N M; Lim, H N; Chia, C H; Yarmo, M A; Muhamad, M R

    2011-01-01

    Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.

  17. Superplasticizer Addition to Carbon Fly Ash Geopolymers Activated at Room Temperature

    Directory of Open Access Journals (Sweden)

    Lorenza Carabba

    2016-07-01

    Full Text Available Present concerns about global warming due to the greenhouse emissions in the atmosphere have pushed the cement industry to research alternatives to ordinary Portland cement (OPC. Geopolymer binder may constitute a possible breakthrough in the development of sustainable materials: understanding the effectiveness and the influences of superplasticizers on geopolymer systems is one of the essential requirements for its large-scale implementation. This study aims to investigate the possibility of using commercially available chemical admixtures designed for OPC concrete, to improve fresh properties of fly ash-based geopolymers and mortars. A special emphasis is laid upon evaluating their influence on mechanical and microstructural characteristics of the hardened material realized under room-temperature curing conditions. Results indicate that the addition of a polycarboxylic ether-based superplasticizer, in the amount of 1.0 wt. % by mass of fly ash, promotes an improvement in workability without compromising the final strength of the hardened material. Moreover, the addition of the polycarboxylic ether- and acrylic-based superplasticizers induces a refinement in the pore structure of hardened mortar leading to a longer water saturation time.

  18. Novel spintronics devices for memory and logic: prospects and challenges for room temperature all spin computing

    Science.gov (United States)

    Wang, Jian-Ping

    An energy efficient memory and logic device for the post-CMOS era has been the goal of a variety of research fields. The limits of scaling, which we expect to reach by the year 2025, demand that future advances in computational power will not be realized from ever-shrinking device sizes, but rather by innovative designs and new materials and physics. Magnetoresistive based devices have been a promising candidate for future integrated magnetic computation because of its unique non-volatility and functionalities. The application of perpendicular magnetic anisotropy for potential STT-RAM application was demonstrated and later has been intensively investigated by both academia and industry groups, but there is no clear path way how scaling will eventually work for both memory and logic applications. One of main reasons is that there is no demonstrated material stack candidate that could lead to a scaling scheme down to sub 10 nm. Another challenge for the usage of magnetoresistive based devices for logic application is its available switching speed and writing energy. Although a good progress has been made to demonstrate the fast switching of a thermally stable magnetic tunnel junction (MTJ) down to 165 ps, it is still several times slower than its CMOS counterpart. In this talk, I will review the recent progress by my research group and my C-SPIN colleagues, then discuss the opportunities, challenges and some potential path ways for magnetoresitive based devices for memory and logic applications and their integration for room temperature all spin computing system.

  19. Computational Intelligence Approach for Estimating Superconducting Transition Temperature of Disordered MgB2 Superconductors Using Room Temperature Resistivity

    Directory of Open Access Journals (Sweden)

    Taoreed O. Owolabi

    2016-01-01

    Full Text Available Doping and fabrication conditions bring about disorder in MgB2 superconductor and further influence its room temperature resistivity as well as its superconducting transition temperature (TC. Existence of a model that directly estimates TC of any doped MgB2 superconductor from the room temperature resistivity would have immense significance since room temperature resistivity is easily measured using conventional resistivity measuring instrument and the experimental measurement of TC wastes valuable resources and is confined to low temperature regime. This work develops a model, superconducting transition temperature estimator (STTE, that directly estimates TC of disordered MgB2 superconductors using room temperature resistivity as input to the model. STTE was developed through training and testing support vector regression (SVR with ten experimental values of room temperature resistivity and their corresponding TC using the best performance parameters obtained through test-set cross validation optimization technique. The developed STTE was used to estimate TC of different disordered MgB2 superconductors and the obtained results show excellent agreement with the reported experimental data. STTE can therefore be incorporated into resistivity measuring instruments for quick and direct estimation of TC of disordered MgB2 superconductors with high degree of accuracy.

  20. Graphene-based room-temperature implementation of a modified Deutsch-Jozsa quantum algorithm.

    Science.gov (United States)

    Dragoman, Daniela; Dragoman, Mircea

    2015-12-04

    We present an implementation of a one-qubit and two-qubit modified Deutsch-Jozsa quantum algorithm based on graphene ballistic devices working at room temperature. The modified Deutsch-Jozsa algorithm decides whether a function, equivalent to the effect of an energy potential distribution on the wave function of ballistic charge carriers, is constant or not, without measuring the output wave function. The function need not be Boolean. Simulations confirm that the algorithm works properly, opening the way toward quantum computing at room temperature based on the same clean-room technologies as those used for fabrication of very-large-scale integrated circuits.

  1. Rechargeable Room-Temperature Na-CO2 Batteries.

    Science.gov (United States)

    Hu, Xiaofei; Sun, Jianchao; Li, Zifan; Zhao, Qing; Chen, Chengcheng; Chen, Jun

    2016-05-23

    Developing rechargeable Na-CO2 batteries is significant for energy conversion and utilization of CO2 . However, the reported batteries in pure CO2 atmosphere are non-rechargeable with limited discharge capacity of 200 mAh g(-1) . Herein, we realized the rechargeability of a Na-CO2 battery, with the proposed and demonstrated reversible reaction of 3 CO2 +4 Na↔2 Na2 CO3 +C. The battery consists of a Na anode, an ether-based electrolyte, and a designed cathode with electrolyte-treated multi-wall carbon nanotubes, and shows reversible capacity of 60000 mAh g(-1) at 1 A g(-1) (≈1000 Wh kg(-1) ) and runs for 200 cycles with controlled capacity of 2000 mAh g(-1) at charge voltage CO2 .

  2. Miyaura Borylations of Aryl Bromides in Water at Room Temperature

    OpenAIRE

    Lipshutz, Bruce H.; Moser, Ralph; Voigtritter, Karl R.

    2010-01-01

    New technology for palladium-catalyzed cross-couplings between B2pin2 and aryl bromides leading to arylboronates is described. Micellar catalysis serves to enable borylations to take place in water as the only medium at ambient temperatures.

  3. Room temperature synthesis and high temperature frictional study of silver vanadate nanorods.

    Science.gov (United States)

    Singh, D P; Polychronopoulou, K; Rebholz, C; Aouadi, S M

    2010-08-13

    We report the room temperature (RT) synthesis of silver vanadate nanorods (consisting of mainly beta-AgV O(3)) by a simple wet chemical route and their frictional study at high temperatures (HT). The sudden mixing of ammonium vanadate with silver nitrate solution under constant magnetic stirring resulted in a pale yellow coloured precipitate. Structural/microstructural characterization of the precipitate through x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the high yield and homogeneous formation of silver vanadate nanorods. The length of the nanorods was 20-40 microm and the thickness 100-600 nm. The pH variation with respect to time was thoroughly studied to understand the formation mechanism of the silver vanadate nanorods. This synthesis process neither demands HT, surfactants nor long reaction time. The silver vanadate nanomaterial showed good lubrication behaviour at HT (700 degrees C) and the friction coefficient was between 0.2 and 0.3. HT-XRD revealed that AgV O(3) completely transformed into silver vanadium oxide (Ag(2)V(4)O(11)) and silver with an increase in temperature from RT to 700 degrees C.

  4. Thermal properties of solids at room and cryogenic temperatures

    CERN Document Server

    Ventura, Guglielmo

    2014-01-01

    This book is a guide for materials scientists, physicists, chemists and engineers who wish to explore the field of low-temperature material properties. The focus is on heat capacity, thermal expansion and electrical and thermal conductivity. The authors report a wide range of experimental details and data, and have compiled useful tables of low-temperature data. Each chapter of the book starts by addressing the theoretical basis of the phenomena. This is a concise presentation, but it helps the reader to develop a deeper understanding of the experiments. The second part of the chapters is dedicated to describing the main experimental techniques to measure thermal properties at low and very low temperature ranges. The final part of each chapter provides a wealth of relevant experimental data in the form of tables and graphs.

  5. Development of permanent magnetic refrigerator at room temperature

    Institute of Scientific and Technical Information of China (English)

    HUANG Jiaohong; LIU Jinrong; JIN Peiyu; YAN Hongwei; QIU Jufeng; XU Laizi; ZHANG Jiuxing

    2006-01-01

    A reciprocating magnetic refrigerator was developed based on the active magneticregeneration technology. Rare earth metal Gd and intermetallic compound LaFe11.2Co0.7Si1.1 were used as the magnetic operating materials in the machine. The particles of the magnetic operating materials, with diameter of 0.5- 2 mm and total mass of 950 g, were mounted in the cooling bed. A magnetic field was assembled using NdFeB rare earth permanent magnets. It had the magneticfield space of Φ 34×200 and the magnetic induction of 1.5 T. The water at pH=10 is used as a heat transfer fluid. When the ambient temperature is 296 K, a temperature span of 18 K was achieved after operation of 45 min at a frequency of 0.178 Hz. The temperature span and the output power increase significantly with the increasing velocity of heat transfer.

  6. Room and low temperature synthesis of carbon nanofibres

    CERN Document Server

    Boskovic, B O

    2002-01-01

    Carbon nanotubes and nanofibres have attracted attention in recent years as new materials with a number of very promising potential applications. Carbon nanotubes are potential candidates for field emitters in flat panel displays. Carbon nanofibres could also be used as a hydrogen storage material and as a filling material in polymer composites. Carbon nanotubes are already used as tips in scanning probe microscopy due to their remarkable mechanical and electrical properties, and could be soon used as nanotweezers. Use of carbon nanotubes in nanoelectronics will open further miniaturisation prospects. Temperatures ranging from 450 to 1000 deg C have been a required for catalytic growth of carbon nanotubes and nanofibres. Researchers have been trying to reduce the growth temperatures for decades. Low temperature growth conditions will allow the growth of carbon nanotubes on different substrates, such glass (below 650 deg C) and as plastics (below 150 deg C) over relatively large areas, which is especially suit...

  7. Room temperature texturing of austenite/ferrite steel by electropulsing

    Science.gov (United States)

    Rahnama, Alireza; Qin, Rongshan

    2017-01-01

    The work reports an experimental observation on crystal rotation in a duplex (austenite + ferrite) steel induced by the electropulsing treatment at ambient temperature, while the temperature rising due to ohmic heating in the treatment was negligible. The results demonstrate that electric current pulses are able to dissolve the initial material’s texture that has been formed in prior thermomechanical processing and to produce an alternative texture. The results were explained in terms of the instability of an interface under perturbation during pulsed electromigation. PMID:28195181

  8. Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

    KAUST Repository

    Lin, Aigu L.

    2015-06-23

    Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

  9. Corner strength enhancement of high strength cold-formed steel at normal room and elevated temperatures

    Institute of Scientific and Technical Information of China (English)

    Ju CHEN; Wei-liang JIN

    2008-01-01

    In this study,the suitability of current design methods for the 0.2% proof yield strength of the comer regions for high strength cold-formed steel at norrnal room temperature was investigated.The current standard predictions are generally accurate for outer comer specimen but conservative for inner comer specimen.Based on the experimental results,an analytical model to predict the comer strength of high strength cold-formed steel at normal room temperature was also proposed.The comparison indicated that the proposed model predicted well the comer strength of high strength cold-formed steel not only at normal room temperature but also at elevated temperatures.It is shown that the predictions obtained from the proposed model agree well with the test results.Generally the comer strength enhancement of high strength cold-formed steel decreases when the temperature increases.

  10. A Promising New Method to Estimate Drug-Polymer Solubility at Room Temperature

    DEFF Research Database (Denmark)

    Knopp, Matthias Manne; Gannon, Natasha; Porsch, Ilona

    2016-01-01

    The established methods to predict drug-polymer solubility at room temperature either rely on extrapolation over a long temperature range or are limited by the availability of a liquid analogue of the polymer. To overcome these issues, this work investigated a new methodology where the drug......-polymer solubility is estimated from the solubility of the drug in a solution of the polymer at room temperature using the shake-flask method. Thus, the new polymer in solution method does not rely on temperature extrapolations and only requires the polymer and a solvent, in which the polymer is soluble, that does...... not affect the molecular structure of the drug and polymer relative to that in the solid state. Consequently, as this method has the potential to provide fast and precise estimates of drug-polymer solubility at room temperature, we encourage the scientific community to further investigate this principle both...

  11. Can doping graphite trigger room temperature superconductivity? Evidence for granular high-temperature superconductivity in water-treated graphite powder.

    Science.gov (United States)

    Scheike, T; Böhlmann, W; Esquinazi, P; Barzola-Quiquia, J; Ballestar, A; Setzer, A

    2012-11-14

    Granular superconductivity in powders of small graphite grains (several tens of micrometers) is demonstrated after treatment with pure water. The temperature, magnetic field and time dependence of the magnetic moment of the treated graphite powder provides evidence for the existence of superconducting vortices with some similarities to high-temperature granular superconducting oxides but even at temperatures above 300 K. Room temperature superconductivity in doped graphite or at its interfaces appears to be possible.

  12. Free radical (co)polymerization of methyl methacrylate and styrene in room temperature ionic liquids

    Science.gov (United States)

    Zhang, Hongwei

    Conventional free radical polymerizations were carried out in a variety of room temperature ionic liquids (RTILs). Generally, methyl methacrylate (MMA) and styrene (St) were used as typical monomers to compare the polymerization behavior both in RTILs and in common volatile organic compound solvents (VOCs). In most cases, it was observed that both yields and molecular weights are enhanced in the RTIL. While we believe the "diffusion-controlled termination" mechanism makes the termination of the radical propagating chains difficult due to the highly viscous nature of RTIL, other researchers have suggested that the rapid polymerization rates are due to the high polarity of these reaction media. By employing more than a dozen RTILs with a wide range of anions and cations, we attempted to correlate the viscosity and polarity of the RTILs with the molecular weights and polymerization rates. This correlation was not successful, suggesting that other parameters may also play a role in affecting the polymerization behavior. Other kinds of polymerizations have also been attempted including nitroxide-mediated living radical polymerizations of St and MMA in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6), and redox initiation system initiated polymerization of MMA through redox pair formed by cation of trihexyl-tetradecyl-phosphonium bis(2,4,4-trimethylpentyl) phosphinate ([H3TDP] [(PM3) 2P]) and BPO. The formation of PSt-b-PMMA by sequential monomer addition through the standard free radical polymerization mechanism, using BPO as initiator, can be realized in [BMIM]PF6 due to the insolubility of polymerized first block---PSt in [BMIM]PF6. The macroradicals wrapped inside the chain coils have prolonged lifetimes because of the diminished termination, which allow some of these radicals to initiate polymerization of MMA at room temperature to form diblock copolymer. Solvents effects on reactivity ratios for free radical statistical copolymerization have been

  13. Energy savings from extended air temperature setpoints and reductions in room air mixing

    OpenAIRE

    Hoyt, Tyler; Lee, Kwang Ho; Zhang, Hui; Arens, Edward; Webster, Tom

    2005-01-01

    Large amounts of energy are consumed by air-conditioning systems to maintain tight control of air temperature in rooms--a narrow range of temperature excursion from neutral, and a uniform temperature in the ambient space. However, both field and lab studies are showing that neither narrow range nor uniformity is really necessary for providing occupant comfort. Data from several large field studies shows occupants accepting a much wider temperature range than is typically applied in practice (...

  14. Prediction of Air Flow and Temperature Distribution Inside a Yogurt Cooling Room Using Computational Fluid Dynamics

    Directory of Open Access Journals (Sweden)

    A Surendhar

    2015-01-01

    Full Text Available Air flow and heat transfer inside a yogurt cooling room were analysed using Computational Fluid Dynamics. Air flow and heat transfer models were based on 3D, unsteady state, incompressible, Reynolds-averaged Navier-Stokes equations and energy equations. Yogurt cooling room was modelled with the measured geometry using 3D design tool AutoCAD. Yogurt cooling room model was exported into the flow simulation software by specifying properties of inlet air, yogurt, pallet and walls of the room. Packing material was not considered in this study because of less thickness (cup-0.5mm, carton box-1.5mm and negligible resistance created in the conduction of heat. 3D Computational domain was meshed with hexahedral cells and governing equations were solved using explicit finite volume method. Air flow pattern inside the room and the temperature distribution in the bulk of palletized yogurt were predicted. Through validation, the variation in the temperature distribution and velocity vector from the measured value was found to be 2.0oC (maximum and 30% respectively. From the simulation and the measured value of the temperature distribution, it was observed that the temperature was non-uniform over the bulk of yogurt. This might be due to refrigeration capacity, air flow pattern, stacking of yogurt or geometry of the room. Required results were achieved by changing the location of the cooling fan.

  15. Effects of ambient room temperature on cold air cooling during laser hair removal.

    Science.gov (United States)

    Ram, Ramin; Rosenbach, Alan

    2007-09-01

    Forced air cooling is a well-established technique that protects the epidermis during laser heating of deeper structures, thereby allowing for increased laser fluences. The goal of this prospective study was to identify whether an elevation in ambient room temperature influences the efficacy of forced air cooling. Skin surface temperatures were measured on 24 sites (12 subjects) during cold air exposure in examination rooms with ambient temperatures of 72 degrees F (22.2 degrees C) and 82 degrees F (27.8 degrees C), respectively. Before cooling, mean skin surface temperature was 9 degrees F (5 degrees C) higher in the warmer room (P cooling (within 1 s), the skin surface temperature remained considerably higher (10.75 degrees F, or 5.8 degrees C, P cooling in a room with an ambient temperature of 82 degrees F (27.8 degrees C) is not as effective as in a room that is at 72 degrees F (22.2 degrees C).

  16. Hydrogen-incorporation stabilization of metallic VO2(R) phase to room temperature, displaying promising low-temperature thermoelectric effect.

    Science.gov (United States)

    Wu, Changzheng; Feng, Feng; Feng, Jun; Dai, Jun; Peng, Lele; Zhao, Jiyin; Yang, Jinlong; Si, Cheng; Wu, Ziyu; Xie, Yi

    2011-09-07

    Regulation of electron-electron correlation has been found to be a new effective way to selectively control carrier concentration, which is a crucial step toward improving thermoelectric properties. The pure electronic behavior successfully stabilized the nonambient metallic VO(2)(R) to room temperature, giving excellent thermoelectric performance among the simple oxides with wider working temperature ranges.

  17. Direct synthesis of ultrafine tetragonal BaTiO3 nanoparticles at room temperature

    Directory of Open Access Journals (Sweden)

    Hu Yong

    2011-01-01

    Full Text Available Abstract A large quantity of ultrafine tetragonal barium titanate (BaTiO3 nanoparticles is directly synthesized at room temperature. The crystalline form and grain size are checked by both X-ray diffraction and transmission electron microscopy. The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized. The phase transition of the as-prepared nanoparticles is investigated by the temperature-dependent Raman spectrum and shows the similar tendency to that of bulk BaTiO3 materials. It is confirmed that the nanoparticles have tetragonal phase at room temperature.

  18. Sphere-to-rod transition of triblock copolymer micelles at room temperature

    Indian Academy of Sciences (India)

    R Ganguly; V K Aswal; P A Hassan; I K Gopalakrishnan; J V Yakhmi

    2004-08-01

    A room temperature sphere-to-rod transition of the polyethylene oxide-polypropylene oxide-polyethylene oxide-based triblock copolymer, (PEO)20 (PPO)70 (PEO)20 micelles have been observed in aqueous medium under the influence of ethanol and sodium chloride. Addition of 5-10% ethanol induces a high temperature sphere-to-rod transition of the micelles, which is brought to room temperature upon addition of NaCl. The inference about the change in the shape of the micelles has been drawn from small-angle neutron scattering (SANS) and viscosity studies.

  19. Room-temperature observations of the weak localization in low-mobility graphene films

    Energy Technology Data Exchange (ETDEWEB)

    Han, Junhao; Wang, Shanyue; Qian, Di; Song, Fengqi, E-mail: songfengqi@nju.edu.cn, E-mail: bgwang@nju.edu.cn; Wang, Baigeng, E-mail: songfengqi@nju.edu.cn, E-mail: bgwang@nju.edu.cn; Han, Min; Zhou, Jianfeng [National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Wang, Xinran; Wang, Xuefeng [School of Electrical and Electronic Engineering, Nanjing University, Nanjing 210093 (China)

    2013-12-07

    We report room-temperature observations of the quantum conductance corrections caused by the weak localization in graphene films synthesized using solid-state-source chemical vapor deposition. Both Raman spectroscopy and Hall measurements showed strong disorder in the samples with a low mobility of ∼430 cm{sup 2}/V s. The emergence of weak localization at room temperature arises from the competition between the valley-dependent scattering and the thermal dephasing in such low-quality samples, although quantum effects normally appear in the samples that have an ideal structure at cryogenic temperatures. The large disorder in our low-mobility samples unexpectedly preserved the quantum mechanical weak localization.

  20. DIMENSIONAL INSTABILITY OF LD31 Al ALLOY WELDMENTS AT ROOM TEMPERATURE AND AFTER THERMAL CYCLES

    Institute of Scientific and Technical Information of China (English)

    X.S. Liu; H.Y. Fang; W.L. Xu; X.T. Tian; X.D. Sun

    2004-01-01

    The unstable dimensional distortion of LD31 aluminum alloy weldments at room temperature and after thermal cycles was studied by use of light interference and CMM(three-coordinate measuring machines). At the same time, distortion mechanism was analyzed from the viewpoint of mechanics and microstructure. Experimental results show that there exists obvious difference of unstable dimensional distortion between LD31 welded specimens under two conditions mentioned above. Under room temperature, dimensional variation of welded specimens will decrease gradually and finally tends to be stable during 200h after welding. The relative elongation of welded specimen is 3.0×10-5; After thermal cycles, distortion of welded specimen is much larger than that at room temperature. After 11 thermal cycles, the dimension will tend to be stable. Dimensional unstable distortion of weldments mainly results from temperature condition, microstructure variation and relaxation of welding residual stress.

  1. Room-temperature ferroelectricity of SrTiO{sub 3} films modulated by cation concentration

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fang; Zhang, Qinghua; Yang, Zhenzhong; Gu, Junxing; Liang, Yan; Li, Wentao; Wang, Weihua [Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Jin, Kuijuan; Gu, Lin; Guo, Jiandong, E-mail: jdguo@iphy.ac.cn [Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100871 (China)

    2015-08-24

    The room-temperature ferroelectricity of SrTiO{sub 3} is promising for oxide electronic devices controlled by multiple fields. An effective way to control the ferroelectricity is highly demanded. Here, we show that the off-centered antisite-like defects in SrTiO{sub 3} films epitaxially grown on Si (001) play the determinative role in the emergence of room-temperature ferroelectricity. The density of these defects changes with the film cation concentration sensitively, resulting in a varied coercive field of the ferroelectric behavior. Consequently, the room-temperature ferroelectricity of SrTiO{sub 3} films can be effectively modulated by tuning the temperature of metal sources during the molecular beam epitaxy growth. Such an easy and reliable modulation of the ferroelectricity enables the flexible engineering of multifunctional oxide electronic devices.

  2. Dimensional instability of LF21 aluminum alloy weldments at room temperature and after thermal cycles

    Institute of Scientific and Technical Information of China (English)

    刘雪松; 田锡唐; 徐文立

    2002-01-01

    The unstable dimensional distortion of LF21 aluminum alloy weldments at room temperature and after thermal cycles was studied by use of light interference and CMM. At the same time, distortion mechanism was analyzed from the viewpoint of mechanics and microstructure. Experimental results show that there exists obvious difference of unstable dimensional distortion between LF21 welded specimens under two conditions mentioned above. Under room temperature, dimensional variation of welded specimens will decrease gradually and finally tends to be stable during 130 h after welding. The relative elongation of welded specimen is 4.2×10-5. After thermal cycles, distortion of welded specimen is much larger than that at room temperature. After 11 thermal cycles, the dimension will tend to be stable. Dimensional unstable distortion of weldments mainly results from temperature condition, microstructure variation and relaxation of welding residual stress.

  3. Room temperature ferromagnetism in undoped ZnO nanofibers prepared by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Kumar Das, Arnab, E-mail: arnab.das@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Kar, Manoranjan, E-mail: mano@iitp.ac.in [Department of Physics, Indian Institute of Technology Patna, Patna 800013 (India); Srinivasan, Ananthakrishanan, E-mail: asrini@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

    2014-09-01

    We report ferromagnetic behavior in undoped ZnO nanofibers prepared by electrospinning a solution of zinc acetate and poly vinyl alcohol followed by annealing at 550 °C for about 90 min. X-ray diffraction patterns of the heat treated as-spun composite fibers reveal the formation of ZnO nanowires in wurtzite structure with no noticeable impurity phases. ZnO nanowires annealed between 500 °C and 600 °C exhibited room temperature ferromagnetism with decreasing magnetization with increasing annealing temperature. Room temperature ferromagnetism was observed in as-spun fibers annealed in air as well as under vacuum. However, vacuum annealed nanofibers show higher magnetization as compared to air annealed fibers, which indicates that oxygen vacancy is a cause for the observed room temperature ferromagnetism in the ZnO nanofibers.

  4. Hydroxyapatite foam as a catalyst for formaldehyde combustion at room temperature.

    Science.gov (United States)

    Xu, Jing; White, Tim; Li, Ping; He, Chongheng; Han, Yi-Fan

    2010-09-29

    The excellent performance of hydroxyapatite, a novel non-precious metal catalyst, for formaldehyde (HCHO) combustion at room temperature is reported. Temperature-programmed surface reaction results indicated that hydroxyl groups bonded with the channel Ca(2+) may be responsible for adsorption/activation of HCHO.

  5. Fluorescence action spectra of algae and bean leaves at room and at liquid nitrogen temperatures

    NARCIS (Netherlands)

    Goedheer, J.C.

    1965-01-01

    Fluorescence action spectra were determined, both at room temperature and at liquid nitrogen temperature, with various blue-green, red and green algae, and greening bean leaves. The action spectra of algae were established with samples of low light absorption as well as dense samples. Fluorescence

  6. Possible room temperature superconductivity in conductors obtained by bringing alkanes into contact with a graphite surface

    Directory of Open Access Journals (Sweden)

    Yasushi Kawashima

    2013-05-01

    Full Text Available Electrical resistances of conductors obtained by bringing alkanes into contact with a graphite surface have been investigated at room temperatures. Ring current in a ring-shaped container into which n-octane-soaked thin graphite flakes were compressed did not decay for 50 days at room temperature. After two HOPG plates were immersed into n-heptane and n-octane at room temperature, changes in resistances of the two samples were measured by four terminal technique. The measurement showed that the resistances of these samples decrease to less than the smallest resistance that can be measured with a high resolution digital voltmeter (0.1μV. The observation of persistent currents in the ring-shaped container suggests that the HOPG plates immersed in n-heptane and n-octane really entered zero-resistance state at room temperature. These results suggest that room temperature superconductor may be obtained by bringing alkanes into contact with a graphite surface.

  7. Room Temperature Magnetic Barrier Layers in Magnetic Tunnel Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Nelson-Cheeseman, B. B.; Wong, F. J.; Chopdekar, R. V.; Arenholz, E.; Suzuki, Y.

    2010-03-09

    We investigate the spin transport and interfacial magnetism of magnetic tunnel junctions with highly spin polarized LSMO and Fe3O4 electrodes and a ferrimagnetic NiFe2O4 (NFO) barrier layer. The spin dependent transport can be understood in terms of magnon-assisted spin dependent tunneling where the magnons are excited in the barrier layer itself. The NFO/Fe3O4 interface displays strong magnetic coupling, while the LSMO/NFO interface exhibits clear decoupling as determined by a combination of X-ray absorption spectroscopy and X-ray magnetic circular dichroism. This decoupling allows for distinct parallel and antiparallel electrode states in this all-magnetic trilayer. The spin transport of these devices, dominated by the NFO barrier layer magnetism, leads to a symmetric bias dependence of the junction magnetoresistance at all temperatures.

  8. Thermoluminescence of photostimulable materials after X irradiation below room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, S.; Iwasa, H.; Kurobori, T.; Inabe, K

    2002-07-01

    Thermoluminescence glow peaks in the temperature range 100 to 400 K are investigated for BaFX (X=Cl, Br) crystals after X irradiation at 100 K. A prominent glow peak of BaFCl around 210 K is found to be composed of a few recombination roots, that is, the peak corresponds to the recombination of hole trapped centers such as an O{sup -} center and a dissociated Cl{sub 2}{sup -} center with the F (F{sup -}) center and the O{sup 2-}-F(Cl{sup -}) pair defect. Another small glow peak around 270 K is likely to occur from thermal dissociation of the O{sup 2-}-F(Cl{sup -}) pair defect. Main glow peak of BaFBr:O{sup 2-} at 170 K may be attributed to a recombination of an O{sup -} center with the F(Br{sup -}) center. (author)

  9. Room temperature synthesis of water-repellent polystyrene nanocomposite coating

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yonggang; Jiang Dong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Zhang Xia; Zhang Zhijun [Laboratory of Special Functional Materials, Henan University, Kaifeng 475001 (China); Wang Qihua, E-mail: wangqh@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2010-09-15

    A stable superhydrophobic polystyrene nanocomposite coating was fabricated by means of a very simple and easy method. The coating was characterized by scanning electron microscopy and X-ray photoelectron spectrum. The wettability of the products was also investigated. By adding the surface-modified SiO{sub 2} nanoparticles, the wettability of the coating changed to water-repellent superhydrophobic, not only for pure water, but also for a wide pH range of corrosive liquids. The influence of the drying temperature and SiO{sub 2} content on the wettability of the nanocomposite coating was also investigated. It was found that both factors had little or no significant effect on the wetting behavior of the coating surface.

  10. Room-Temperature Creation and Spin-Orbit Torque Manipulation of Skyrmions in Thin Films with Engineered Asymmetry.

    Science.gov (United States)

    Yu, Guoqiang; Upadhyaya, Pramey; Li, Xiang; Li, Wenyuan; Kim, Se Kwon; Fan, Yabin; Wong, Kin L; Tserkovnyak, Yaroslav; Amiri, Pedram Khalili; Wang, Kang L

    2016-03-09

    Magnetic skyrmions, which are topologically protected spin textures, are promising candidates for ultralow-energy and ultrahigh-density magnetic data storage and computing applications. To date, most experiments on skyrmions have been carried out at low temperatures. The choice of available materials is limited, and there is a lack of electrical means to control skyrmions in devices. In this work, we demonstrate a new method for creating a stable skyrmion bubble phase in the CoFeB-MgO material system at room temperature, by engineering the interfacial perpendicular magnetic anisotropy of the ferromagnetic layer. Importantly, we also demonstrate that artificially engineered symmetry breaking gives rise to a force acting on the skyrmions, in addition to the current-induced spin-orbit torque, which can be used to drive their motion. This room-temperature creation and manipulation of skyrmions offers new possibilities to engineer skyrmionic devices. The results bring skyrmionic memory and logic concepts closer to realization in industrially relevant and manufacturable thin film material systems.

  11. Elimination of formaldehyde over Cu-Al2O3 catalyst at room temperature.

    Science.gov (United States)

    Zhang, Chang-Bin; Shi, Xiao-Yan; Gao, Hong-Wei; He, Hong

    2005-01-01

    Catalytic elimination of formaldehyde (HCHO) was investigated over Cu-Al2O3 catalyst at room temperature. The results indicated that no oxidation of HCHO into CO2 occurs at room temperature, but the adsorption of HCHO occurs on the catalyst surface. With the increase of gas hourly space velocity (GHSV) and inlet HCHO concentration, the time to reach saturation was shortened proportionally. The results of the in situ DRIFTS, Density functional theory calculations and temperature programmed desorption(TPD) showed that HCHO was completely oxidized into HCOOH over Cu-Al2O3 at room temperature. With increasing the temperature in a flow of helium, HCOOH was completely decomposed into CO2 over the catalyst surface, and the deactivated Cu-Al2O3 is regenerated at the same time. In addition, although Cu had no obvious influence on the adsorption of HCHO on Al2O3, Cu dramatically lowered the decomposition temperature of HCOOH into CO2. It was shown that Cu-Al2O3 catalyst had a good ability for the removal of HCHO, and appeared to be promising for its application in destroying HCHO at room temperature.

  12. Elimination of formaldehyde over Cu-Al2O3 catalyst at room temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chang-bin; SHI Xiao-yan; GAO Hong-wei; HE Hong

    2005-01-01

    Catalytic elimination of formaldehyde(HCHO) was investigated over Cu-Al2O3 catalyst at room temperature. The results indicated that no oxidation of HCHO into CO2 occurs at room temperature, but the adsorption of HCHO occurs on the catalyst surface.With the increase of gas hourly space velocity (GHSV) and inlet HCHO concentration, the time to reach saturation was shortened proportionally. The results of the in situ DRIFTS, Density functional theory calculations and temperature programmed desorption(TPD)showed that HCHO was completely oxidized into HCOOH over Cu-Al2 O3 at room temperature. With increasing the temperature in a flow of helium, HCOOH was completely decomposed into CO2 over the catalyst surface, and the deactivated Cu-Al2 O3 is regenerated at the same time. In addition, although Cu had no obvious influence on the adsorption of HCHO on Al2 O3, Cu dramatically lowered the decomposition temperature of HCOOH into CO2. It was shown that Cu-Al2 O3 catalyst had a good ability for the removal of HCHO, and appeared to be promising for its application in destroying HCHO at room temperature.

  13. Effects of supply air temperature and inlet location on particle dispersion in displacement ventilation rooms

    Institute of Scientific and Technical Information of China (English)

    Yanming Kang; Youjun Wang; Ke Zhong

    2011-01-01

    The effects of supply temperature and vertical location of inlet air on particle dispersion in a displacement ventilated (DV) room were numerically modeled with validation by experimental data from the literature.The results indicate that the temperature and vertical location of inlet supply air did not greatly affect the air distribution in the upper parts of a DV room,but could significantly influence the airflow pattern in the lower parts of the room,thus affecting the indoor air quality with contaminant sources located at the lower level,such as particles from working activities in an office.The numerical results also show that the inlet location would slightly influence the relative ventilation efficiency for the same air supply volume,but particle concentration in the breathing zone would be slightly lower with a low horizontal wall slot than a rectangular diffuser.Comparison of the results for two different supply temperatures in a DV room shows that,although lower supply temperature means less incoming air volume,since the indoor flow is mainly driven by buoyancy,lower supply temperature air could more efficiently remove passive sources (such as particles released from work activities in an office).However,in the breathing zone it gives higher concentration as compared to higher supply air temperature.To obtain good indoor air quality,low supply air temperature should be avoided because concentration in the breathing zone has a stronger and more direct impact on human health.

  14. Al based ultra-fine eutectic with high room temperature plasticity and elevated temperature strength

    Energy Technology Data Exchange (ETDEWEB)

    Tiwary, C.S., E-mail: cst311@gmail.com [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, Karnataka (India); Kashyap, S. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, Karnataka (India); Kim, D.H. [Center for Non-Crystalline Materials, Department of Metallurgical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Chattopadhyay, K. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, Karnataka (India)

    2015-07-15

    Developments of aluminum alloys that can retain strength at and above 250 °C present a significant challenge. In this paper we report an ultrafine scale Al–Fe–Ni eutectic alloy with less than 3.5 at% transition metals that exhibits room temperature ultimate tensile strength of ~400 MPa with a tensile ductility of 6–8%. The yield stress under compression at 300 °C was found to be 150 MPa. We attribute it to the refinement of the microstructure that is achieved by suction casting in copper mold. The characterization using scanning and transmission electron microscopy (SEM and TEM) reveals an unique composite structure that contains the Al–Al{sub 3}Ni rod eutectic with spacing of ~90 nm enveloped by a lamellar eutectic of Al–Al{sub 9}FeNi (~140 nm). Observation of subsurface deformation under Vickers indentation using bonded interface technique reveals the presence of extensive shear banding during deformation that is responsible for the origin of ductility. The dislocation configuration in Al–Al{sub 3}Ni eutectic colony indicates accommodation of plasticity in α-Al with dislocation accumulation at the α-Al/Al{sub 3}Ni interface boundaries. In contrast the dislocation activities in the intermetallic lamellae are limited and contain set of planner dislocations across the plates. We present a detailed analysis of the fracture surface to rationalize the origin of the high strength and ductility in this class of potentially promising cast alloy.

  15. Hydrogen reduction of molybdenum oxide at room temperature

    Science.gov (United States)

    Borgschulte, Andreas; Sambalova, Olga; Delmelle, Renaud; Jenatsch, Sandra; Hany, Roland; Nüesch, Frank

    2017-01-01

    The color changes in chemo- and photochromic MoO3 used in sensors and in organic photovoltaic (OPV) cells can be traced back to intercalated hydrogen atoms stemming either from gaseous hydrogen dissociated at catalytic surfaces or from photocatalytically split water. In applications, the reversibility of the process is of utmost importance, and deterioration of the layer functionality due to side reactions is a critical challenge. Using the membrane approach for high-pressure XPS, we are able to follow the hydrogen reduction of MoO3 thin films using atomic hydrogen in a water free environment. Hydrogen intercalates into MoO3 forming HxMoO3, which slowly decomposes into MoO2 +1/2 H2O as evidenced by the fast reduction of Mo6+ into Mo5+ states and slow but simultaneous formation of Mo4+ states. We measure the decrease in oxygen/metal ratio in the thin film explaining the limited reversibility of hydrogen sensors based on transition metal oxides. The results also enlighten the recent debate on the mechanism of the high temperature hydrogen reduction of bulk molybdenum oxide. The specific mechanism is a result of the balance between the reduction by hydrogen and water formation, desorption of water as well as nucleation and growth of new phases.

  16. Road to room-temperature superconductivity: A universal model

    CERN Document Server

    Bucher, Manfred

    2013-01-01

    In a semiclassical view superconductivity is attributed exclusively to the advance of atoms' outer s electrons through the nuclei of neighbor atoms in a solid. The necessary progression of holes in the opposite direction has the electric and magnetic effect as if two electrons were advancing instead of each actual one. Superconductivity ceases when the associated lateral oscillation of the outer s electrons extends between neighbor atoms. If such overswing occurs already at T = 0, then the material is a normal conductor. Otherwise, lateral overswing can be caused by lattice vibrations at a critical temperature Tc or by a critical magnetic field Bc. Lateral electron oscillations are reduced - and Tc is increased - when the atoms of the outer s electrons are squeezed, be it in the bulk crystal, in a thin film, or under external pressure on the sample. The model is applied to alkali metals and alkali-doped fullerenes. Aluminum serves as an example of a simple metal with superconductivity. Application of the mode...

  17. Formation of crystalline telluridomercurates from ionic liquids near room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Donsbach, Carsten; Dehnen, Stefanie [Fachbereich Chemie und Wissenschaftliches Zentrum fuer Materialwissenschaften, Philipps-Universitaet Marburg, Hans-Meerwein-Strasse 4, 35043, Marburg (Germany)

    2017-01-15

    The ternary telluridomercurate Na{sub 2}[HgTe{sub 2}] (1) was formed by fusion of Na{sub 2}Te and HgTe at 600 C and further treated in the ionic liquid (C{sub 4}C{sub 1}Im)[BF{sub 4}] (C{sub 4}C{sub 1}Im = 1-butyl-3-methylimidazolium) at moderately elevated temperatures (60 C), leading to replacement of the Na{sup +} cations with (C{sub 4}C{sub 1}Im){sup +} and re-arrangement of the inorganic substructure. As a result, we obtained the telluridomercurate (C{sub 4}C{sub 1}Im){sub 2}[HgTe{sub 2}] (2) and the tellurido/ditelluridomercurate (C{sub 4}C{sub 1}Im){sub 2}[Hg{sub 2}Te{sub 4}] (3) besides polytellurides and HgTe as by-products. The heavy atom compositions of the compounds were confirmed by micro X-ray fluorescence spectroscopy (μ-XFS), and their structures were determined by single-crystal diffraction. The cation-exchanged salts were further investigated by UV/Vis spectroscopy, indicating narrow band-gap optical transitions at 2.80 eV (2) and 1.63 eV (3), in agreement with their visible yellow or reddish-black color, respectively. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. A moment model for phonon transport at room temperature

    Science.gov (United States)

    Mohammadzadeh, Alireza; Struchtrup, Henning

    2017-01-01

    Heat transfer in solids is modeled by deriving the macroscopic equations for phonon transport from the phonon-Boltzmann equation. In these equations, the Callaway model with frequency-dependent relaxation time is considered to describe the Resistive and Normal processes in the phonon interactions. Also, the Brillouin zone is considered to be a sphere, and its diameter depends on the temperature of the system. A simple model to describe phonon interaction with crystal boundary is employed to obtain macroscopic boundary conditions, where the reflection kernel is the superposition of diffusive reflection, specular reflection and isotropic scattering. Macroscopic moments are defined using a polynomial of the frequency and wave vector of phonons. As an example, a system of moment equations, consisting of three directional and seven frequency moments, i.e., 63 moments in total, is used to study one-dimensional heat transfer, as well as Poiseuille flow of phonons. Our results show the importance of frequency dependency in relaxation times and macroscopic moments to predict rarefaction effects. Good agreement with data reported in the literature is obtained.

  19. Ultrafast room temperature single-photon source from nanowire-quantum dots.

    Science.gov (United States)

    Bounouar, S; Elouneg-Jamroz, M; Hertog, M den; Morchutt, C; Bellet-Amalric, E; André, R; Bougerol, C; Genuist, Y; Poizat, J-Ph; Tatarenko, S; Kheng, K

    2012-06-13

    Epitaxial semiconductor quantum dots are particularly promising as realistic single-photon sources for their compatibility with manufacturing techniques and possibility to be implemented in compact devices. Here, we demonstrate for the first time single-photon emission up to room temperature from an epitaxial quantum dot inserted in a nanowire, namely a CdSe slice in a ZnSe nanowire. The exciton and biexciton lines can still be resolved at room temperature and the biexciton turns out to be the most appropriate transition for single-photon emission due to a large nonradiative decay of the bright exciton to dark exciton states. With an intrinsically short radiative decay time (≈300 ps) this system is the fastest room temperature single-photon emitter, allowing potentially gigahertz repetition rates.

  20. Quality of Red Blood Cells Isolated from Umbilical Cord Blood Stored at Room Temperature

    Directory of Open Access Journals (Sweden)

    Mariia Zhurova

    2012-01-01

    Full Text Available Red blood cells (RBCs from cord blood contain fetal hemoglobin that is predominant in newborns and, therefore, may be more appropriate for neonatal transfusions than currently transfused adult RBCs. Post-collection, cord blood can be stored at room temperature for several days before it is processed for stem cells isolation, with little known about how these conditions affect currently discarded RBCs. The present study examined the effect of the duration cord blood spent at room temperature and other cord blood characteristics on cord RBC quality. RBCs were tested immediately after their isolation from cord blood using a broad panel of quality assays. No significant decrease in cord RBC quality was observed during the first 65 hours of storage at room temperature. The ratio of cord blood to anticoagulant was associated with RBC quality and needs to be optimized in future. This knowledge will assist in future development of cord RBC transfusion product.

  1. Polymer functionalized nanostructured porous silicon for selective water vapor sensing at room temperature

    Science.gov (United States)

    Dwivedi, Priyanka; Das, Samaresh; Dhanekar, Saakshi

    2017-04-01

    This paper highlights the surface treatment of porous silicon (PSi) for enhancing the sensitivity of water vapors at room temperature. A simple and low cost technique was used for fabrication and functionalization of PSi. Spin coated polyvinyl alcohol (PVA) was used for functionalizing PSi surface. Morphological and structural studies were conducted to analyze samples using SEM and XRD/Raman spectroscopy respectively. Contact angle measurements were performed for assessing the wettability of the surfaces. PSi and functionalized PSi samples were tested as sensors in presence of different analytes like ethanol, acetone, isopropyl alcohol (IPA) and water vapors in the range of 50-500 ppm. Electrical measurements were taken from parallel aluminium electrodes fabricated on the functionalized surface, using metal mask and thermal evaporation. Functionalized PSi sensors in comparison to non-functionalized sensors depicted selective and enhanced response to water vapor at room temperature. The results portray an efficient and selective water vapor detection at room temperature.

  2. Room Temperature Single-Photon Emission from Individual Perovskite Quantum Dots.

    Science.gov (United States)

    Park, Young-Shin; Guo, Shaojun; Makarov, Nikolay S; Klimov, Victor I

    2015-10-27

    Lead-halide-based perovskites have been the subject of numerous recent studies largely motivated by their exceptional performance in solar cells. Electronic and optical properties of these materials have been commonly controlled by varying the composition (e.g., the halide component) and/or crystal structure. Use of nanostructured forms of perovskites can provide additional means for tailoring their functionalities via effects of quantum confinement and wave function engineering. Furthermore, it may enable applications that explicitly rely on the quantum nature of electronic excitations. Here, we demonstrate that CsPbX3 quantum dots (X = I, Br) can serve as room-temperature sources of quantum light, as indicated by strong photon antibunching detected in single-dot photoluminescence measurements. We explain this observation by the presence of fast nonradiative Auger recombination, which renders multiexciton states virtually nonemissive and limits the fraction of photon coincidence events to ∼6% on average. We analyze limitations of these quantum dots associated with irreversible photodegradation and fluctuations ("blinking") of the photoluminescence intensity. On the basis of emission intensity-lifetime correlations, we assign the "blinking" behavior to random charging/discharging of the quantum dot driven by photoassisted ionization. This study suggests that perovskite quantum dots hold significant promise for applications such as quantum emitters; however, to realize this goal, one must resolve the problems of photochemical stability and photocharging. These problems are largely similar to those of more traditional quantum dots and, hopefully, can be successfully resolved using advanced methodologies developed over the years in the field of colloidal nanostructures.

  3. Efficient, resonantly pumped, room-temperature Er3+:GdVO4 laser.

    Science.gov (United States)

    Ter-Gabrielyan, N; Fromzel, V; Ryba-Romanowski, W; Lukasiewicz, T; Dubinskii, M

    2012-04-01

    We report an efficient room-temperature operation of a resonantly pumped Er3+:GdVO4 laser at 1598.5 nm. The maximum continuous wave (CW) output power of 3.5 W with slope efficiency of 56% was achieved with resonant pumping by an Er-fiber laser at 1538.6 nm. With pumping by a commercial laser diode bar stack, a quasi-CW (QCW) output of 7.7 W and maximum slope efficiency of ~53% versus absorbed pump power were obtained. This is believed to be the first resonantly (in-band) pumped, room-temperature Er3+:GdVO4 laser.

  4. Water adsorption on graphene/Pt(111 at room temperature: A vibrational investigation

    Directory of Open Access Journals (Sweden)

    A. Politano

    2011-12-01

    Full Text Available Water interaction with quasi-freestanding graphene deposited on Pt(111 has been investigated by using vibrational spectroscopy. Loss measurements show that water molecules dosed at room temperature can dissociate giving rise to C-H bonds. The formation of the C-H bonds strongly attenuates the optical phonons of the graphene sheet. On the other hand, at 100 K water has been found to adsorb only in molecular state. Present findings should be taken into account in engineering graphene-based devices which should work at atmospheric pressure and at room temperature.

  5. A 2.5-2.7 THz Room Temperature Electronic Source

    Science.gov (United States)

    Maestrini, Alain; Mehdi, Imran; Lin, Robert; Siles, Jose Vicente; Lee, Choonsup; Gill, John; Chattopadhyay, Goutam; Schlecht, Erich; Bertrand, Thomas; Ward, John

    2011-01-01

    We report on a room temperature 2.5 to 2.7 THz electronic source based on frequency multipliers. The source utilizes a cascade of three frequency multipliers with W-band power amplifiers driving the first stage multiplier. Multiple-chip multipliers are utilized for the two initial stages to improve the power handling capability and a sub-micron anode is utilized for the final stage tripler. Room temperature measurements indicate that the source can put out a peak power of about 14 microwatts with more than 4 microwatts in the 2.5 to 2.7 THz range.

  6. Direct On-Surface Patterning of a Crystalline Laminar Covalent Organic Framework Synthesized at Room Temperature.

    Science.gov (United States)

    de la Peña Ruigómez, Alejandro; Rodríguez-San-Miguel, David; Stylianou, Kyriakos C; Cavallini, Massimiliano; Gentili, Denis; Liscio, Fabiola; Milita, Silvia; Roscioni, Otello Maria; Ruiz-González, Maria Luisa; Carbonell, Carlos; Maspoch, Daniel; Mas-Ballesté, Rubén; Segura, José Luis; Zamora, Félix

    2015-07-20

    We report herein an efficient, fast, and simple synthesis of an imine-based covalent organic framework (COF) at room temperature (hereafter, RT-COF-1). RT-COF-1 shows a layered hexagonal structure exhibiting channels, is robust, and is porous to N2 and CO2 . The room-temperature synthesis has enabled us to fabricate and position low-cost micro- and submicropatterns of RT-COF-1 on several surfaces, including solid SiO2 substrates and flexible acetate paper, by using lithographically controlled wetting and conventional ink-jet printing.

  7. Transistor effects and in situ STM of redox molecules at room temperature

    DEFF Research Database (Denmark)

    Albrecht, Tim; Guckian, A; Vos, JG

    2005-01-01

    Inorganic transition metal complexes were identified as potential candidates for transistor-like behavior in an electrochemical scanning tunnelling microscope (STM) configuration at room temperature. The theoretical background has been established based on condensed matter charge transfer theory....... resolution reveal detailed information on their surface structure and scanning tunnelling spectroscopy experiments have shown clear evidence of transistor-like behavior......Inorganic transition metal complexes were identified as potential candidates for transistor-like behavior in an electrochemical scanning tunnelling microscope (STM) configuration at room temperature. The theoretical background has been established based on condensed matter charge transfer theory...

  8. Room temperature ballistic transport in InSb quantum well nanodevices.

    Science.gov (United States)

    Gilbertson, A M; Kormányos, A; Buckle, P D; Fearn, M; Ashley, T; Lambert, C J; Solin, S A; Cohen, L F

    2011-12-12

    We report the room temperature observation of significant ballistic electron transport in shallow etched four-terminal mesoscopic devices fabricated on an InSb/AlInSb quantum well (QW) heterostructure with a crucial partitioned growth-buffer scheme. Ballistic electron transport is evidenced by a negative bend resistance signature which is quite clearly observed at 295 K and at current densities in excess of 10(6) A/cm(2). This demonstrates unequivocally that by using effective growth and processing strategies, room temperature ballistic effects can be exploited in InSb/AlInSb QWs at practical device dimensions.

  9. Room-temperature fabrication of light-emitting thin films based on amorphous oxide semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Junghwan, E-mail: JH.KIM@lucid.msl.titech.ac.jp; Miyokawa, Norihiko; Ide, Keisuke [Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Toda, Yoshitake [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Mailbox SE-6, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Hiramatsu, Hidenori; Hosono, Hideo; Kamiya, Toshio [Materials and Structures Laboratory, Tokyo Institute of Technology, Mailbox R3-4, 4259 Nagatsuta, Midori-ku, Yokohama (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Mailbox SE-6, 4259 Nagatsuta, Midori-ku, Yokohama (Japan)

    2016-01-15

    We propose a light-emitting thin film using an amorphous oxide semiconductor (AOS) because AOS has low defect density even fabricated at room temperature. Eu-doped amorphous In-Ga-Zn-O thin films fabricated at room temperature emitted intense red emission at 614 nm. It is achieved by precise control of oxygen pressure so as to suppress oxygen-deficiency/excess-related defects and free carriers. An electronic structure model is proposed, suggesting that non-radiative process is enhanced mainly by defects near the excited states. AOS would be a promising host for a thin film phosphor applicable to flexible displays as well as to light-emitting transistors.

  10. Exploiting fast detectors to enter a new dimension in room-temperature crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Robin L., E-mail: robin.owen@diamond.ac.uk; Paterson, Neil; Axford, Danny; Aishima, Jun [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Schulze-Briese, Clemens [Dectris Ltd, Neuenhofer Strasse 107, 5400 Baden (Switzerland); Ren, Jingshan; Fry, Elizabeth E. [University of Oxford, The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Stuart, David I. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); University of Oxford, The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Evans, Gwyndaf [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom)

    2014-05-01

    A departure from a linear or an exponential decay in the diffracting power of macromolecular crystals is observed and accounted for through consideration of a multi-state sequential model. A departure from a linear or an exponential intensity decay in the diffracting power of protein crystals as a function of absorbed dose is reported. The observation of a lag phase raises the possibility of collecting significantly more data from crystals held at room temperature before an intolerable intensity decay is reached. A simple model accounting for the form of the intensity decay is reintroduced and is applied for the first time to high frame-rate room-temperature data collection.

  11. Room temperature nanostructured graphene transistor with high on/off ratio

    Science.gov (United States)

    Dragoman, Mircea; Dinescu, Adrian; Dragoman, Daniela

    2017-01-01

    We report the batch fabrication of graphene field-effect-transistors (GFETs) with nanoperforated graphene as channel. The transistors were cut and encapsulated. The encapsulated GFETs display saturation regions that can be tuned by modifying the top gate voltage, and have on/off ratios of at least 2 × 103 at room temperature and at small drain and gate voltages. In addition, the nanoperforated GFETs display orders of magnitude higher photoresponses than any room-temperature graphene detector configurations that do not involve heterostructures with bandgap materials.

  12. Determination of trace calcium by solid substrate-room temperature phosphorimetry

    Institute of Scientific and Technical Information of China (English)

    Jia Ming Liu; Tian Long Yang; Xiao Mei Huang; Xiu Mei Shi; Zhong Bin Shi; Hong Wu; Guo Hui Zhu; Zhi Ming Li; Cui Lian Chen

    2007-01-01

    A new method for the determination of trace calcium by solid substrate-room temperature phosphorimetry is established. It is based on the fact that chromeazurols azurol S-phenanthroline-NaCMC (CAS-phen-NaCMC) system can emit strong and stable room temperature phosphorescence (RTP) on the solid substrate in the filter paper. Ca2+ and phenanthroline can form complex ion Ca(phen)32+, which will form complex [Ca(phen)3(CAS)2] with CAS. In the result, the number of CAS molecules in each spot increased, causing sharp increase of the RTP signal of the CAS-phen-NaCMC system.

  13. Room temperature ethanol sensor based on ZnO prepared via laser ablation in water

    Science.gov (United States)

    Kondo, Takahiro; Sato, Yoshihiro; Kinoshita, Masahiro; Shankar, Prabakaran; Mintcheva, Neli N.; Honda, Mitsuhiro; Iwamori, Satoru; Kulinich, Sergei A.

    2017-08-01

    The present work reports on room-temperature ethanol sensing performance of ZnO nanospheres and nanorods prepared using pulsed laser ablation in water. Nanosecond and millisecond lasers were used to prepare ZnO nanomaterials with hexagonal wurtzite crystal structure. The two contrasting nanostructures were tested as gas sensors towards volatile compounds such as ethanol, ammonia, and acetone. At room temperature, devices based on both ZnO nanomaterials demonstrated selectivity for ethanol vapor. The sensitivity of nanospheres was somewhat higher compared to that of nanorods, with response values of ∼19 and ∼14, respectively, towards 250 ppm. Concentrations as low as 50 ppm could be easily detected.

  14. Magnetic nanostructuring and overcoming Brown's paradox to realize extraordinary high-temperature energy products

    Science.gov (United States)

    Balasubramanian, Balamurugan; Mukherjee, Pinaki; Skomski, Ralph; Manchanda, Priyanka; Das, Bhaskar; Sellmyer, David J.

    2014-09-01

    Nanoscience has been one of the outstanding driving forces in technology recently, arguably more so in magnetism than in any other branch of science and technology. Due to nanoscale bit size, a single computer hard disk is now able to store the text of 3,000,000 average-size books, and today's high-performance permanent magnets--found in hybrid cars, wind turbines, and disk drives--are nanostructured to a large degree. The nanostructures ideally are designed from Co- and Fe-rich building blocks without critical rare-earth elements, and often are required to exhibit high coercivity and magnetization at elevated temperatures of typically up to 180 °C for many important permanent-magnet applications. Here we achieve this goal in exchange-coupled hard-soft composite films by effective nanostructuring of high-anisotropy HfCo7 nanoparticles with a high-magnetization Fe65Co35 phase. An analysis based on a model structure shows that the soft-phase addition improves the performance of the hard-magnetic material by mitigating Brown's paradox in magnetism, a substantial reduction of coercivity from the anisotropy field. The nanostructures exhibit a high room-temperature energy product of about 20.3 MGOe (161.5 kJ/m3), which is a record for a rare earth- or Pt-free magnetic material and retain values as high as 17.1 MGOe (136.1 kJ/m3) at 180°C.

  15. Magnetic nanostructuring and overcoming Brown's paradox to realize extraordinary high-temperature energy products.

    Science.gov (United States)

    Balasubramanian, Balamurugan; Mukherjee, Pinaki; Skomski, Ralph; Manchanda, Priyanka; Das, Bhaskar; Sellmyer, David J

    2014-09-02

    Nanoscience has been one of the outstanding driving forces in technology recently, arguably more so in magnetism than in any other branch of science and technology. Due to nanoscale bit size, a single computer hard disk is now able to store the text of 3,000,000 average-size books, and today's high-performance permanent magnets--found in hybrid cars, wind turbines, and disk drives--are nanostructured to a large degree. The nanostructures ideally are designed from Co- and Fe-rich building blocks without critical rare-earth elements, and often are required to exhibit high coercivity and magnetization at elevated temperatures of typically up to 180 °C for many important permanent-magnet applications. Here we achieve this goal in exchange-coupled hard-soft composite films by effective nanostructuring of high-anisotropy HfCo7 nanoparticles with a high-magnetization Fe65Co35 phase. An analysis based on a model structure shows that the soft-phase addition improves the performance of the hard-magnetic material by mitigating Brown's paradox in magnetism, a substantial reduction of coercivity from the anisotropy field. The nanostructures exhibit a high room-temperature energy product of about 20.3 MGOe (161.5 kJ/m(3)), which is a record for a rare earth- or Pt-free magnetic material and retain values as high as 17.1 MGOe (136.1 kJ/m(3)) at 180°C.

  16. Thermally robust and biomolecule-friendly room-temperature bonding for the fabrication of elastomer-plastic hybrid microdevices.

    Science.gov (United States)

    Nguyen, T P O; Tran, B M; Lee, N Y

    2016-08-16

    Here, we introduce a simple and fast method for bonding a poly(dimethylsiloxane) (PDMS) silicone elastomer to different plastics. In this technique, surface modification and subsequent bonding processes are performed at room temperature. Furthermore, only one chemical is needed, and no surface oxidation step is necessary prior to bonding. This bonding method is particularly suitable for encapsulating biomolecules that are sensitive to external stimuli, such as heat or plasma treatment, and for embedding fracturable materials prior to the bonding step. Microchannel-fabricated PDMS was first oxidized by plasma treatment and reacted with aminosilane by forming strong siloxane bonds (Si-O-Si) at room temperature. Without the surface oxidation of the amine-terminated PDMS and plastic, the two heterogeneous substrates were brought into intimate physical contact and left at room temperature. Subsequently, aminolysis occurred, leading to the generation of a permanent seal via the formation of robust urethane bonds after only 5 min of assembling. Using this method, large-area (10 × 10 cm) bonding was successfully realized. The surface was characterized by contact angle measurements and X-ray photoelectron spectroscopy (XPS) analyses, and the bonding strength was analyzed by performing peel, delamination, leak, and burst tests. The bond strength of the PDMS-polycarbonate (PC) assembly was approximately 409 ± 6.6 kPa, and the assembly withstood the injection of a tremendous amount of liquid with the per-minute injection volume exceeding 2000 times its total internal volume. The thermal stability of the bonded microdevice was confirmed by performing a chamber-type multiplex polymerase chain reaction (PCR) of two major foodborne pathogens - Escherichia coli O157:H7 and Salmonella typhimurium - and assessing the possibility for on-site direct detection of PCR amplicons. This bonding method demonstrated high potential for the stable construction of closed microfluidic systems

  17. Superior room-temperature ductility of typically brittle quasicrystals at small sizes

    Science.gov (United States)

    Zou, Yu; Kuczera, Pawel; Sologubenko, Alla; Sumigawa, Takashi; Kitamura, Takayuki; Steurer, Walter; Spolenak, Ralph

    2016-08-01

    The discovery of quasicrystals three decades ago unveiled a class of matter that exhibits long-range order but lacks translational periodicity. Owing to their unique structures, quasicrystals possess many unusual properties. However, a well-known bottleneck that impedes their widespread application is their intrinsic brittleness: plastic deformation has been found to only be possible at high temperatures or under hydrostatic pressures, and their deformation mechanism at low temperatures is still unclear. Here, we report that typically brittle quasicrystals can exhibit remarkable ductility of over 50% strains and high strengths of ~4.5 GPa at room temperature and sub-micrometer scales. In contrast to the generally accepted dominant deformation mechanism in quasicrystals--dislocation climb, our observation suggests that dislocation glide may govern plasticity under high-stress and low-temperature conditions. The ability to plastically deform quasicrystals at room temperature should lead to an improved understanding of their deformation mechanism and application in small-scale devices.

  18. Cholesteric liquid crystalline materials with a dual circularly polarized light reflection band fixed at room temperature.

    Science.gov (United States)

    Agez, Gonzague; Mitov, Michel

    2011-05-26

    An unpolarized normal-incidence light beam reflected by a cholesteric liquid crystal is left- or right-circularly polarized, in the cholesteric temperature range. In this article, we present a novel approach for fabricating a cholesteric liquid crystalline material that exhibits reflection bands with both senses of polarization at room temperature. A cholesteric liquid crystal that presents a twist inversion at a critical temperature T(c) is blended with a small quantity of photopolymerizable monomers. Upon ultraviolet irradiation above T(c), the liquid crystal becomes a polymer-stabilized liquid crystal. Below T(c), the material reflects a dual circularly polarized band in the infrared. By quenching the experimental cell at a temperature below the blend's melting point, the optical properties of the material in an undercooled state are conserved for months at room temperature, which is critical to potential applications such as heat-repelling windows and polarization-independent photonic devices.

  19. Photochemical Hydrogen Doping Induced Embedded Two-Dimensional Metallic Channel Formation in InGaZnO at Room Temperature.

    Science.gov (United States)

    Kim, Myeong-Ho; Lee, Young-Ahn; Kim, Jinseo; Park, Jucheol; Ahn, Seungbae; Jeon, Ki-Joon; Kim, Jeong Won; Choi, Duck-Kyun; Seo, Hyungtak

    2015-10-27

    The photochemical tunability of the charge-transport mechanism in metal-oxide semiconductors is of great interest since it may offer a facile but effective semiconductor-to-metal transition, which results from photochemically modified electronic structures for various oxide-based device applications. This might provide a feasible hydrogen (H)-radical doping to realize the effectively H-doped metal oxides, which has not been achieved by thermal and ion-implantation technique in a reliable and controllable way. In this study, we report a photochemical conversion of InGaZnO (IGZO) semiconductor to a transparent conductor via hydrogen doping to the local nanocrystallites formed at the IGZO/glass interface at room temperature. In contrast to thermal or ionic hydrogen doping, ultraviolet exposure of the IGZO surface promotes a photochemical reaction with H radical incorporation to surface metal-OH layer formation and bulk H-doping which acts as a tunable and stable highly doped n-type doping channel and turns IGZO to a transparent conductor. This results in the total conversion of carrier conduction property to the level of metallic conduction with sheet resistance of ∼16 Ω/□, room temperature Hall mobility of 11.8 cm(2) V(-1) sec(-1), the carrier concentration at ∼10(20) cm(-3) without any loss of optical transparency. We demonstrated successful applications of photochemically highly n-doped metal oxide via optical dose control to transparent conductor with excellent chemical and optical doping stability.

  20. Bosonic lasing and trapping of a dressed photon fluid in InGaN at room temperature

    Science.gov (United States)

    Cobet, Munise

    2016-08-01

    The generation of a quantum fluid of dressed photons at room temperature is experimentally demonstrated in an InGaN microcavity which is divided into two- and one-dimensional sections, resulting in single- and switchable multilevel coherent light emission. Ultra-low-threshold operation is attributed to the slight but robust excitonic fraction of the photonic condensate representing a bosonic laser working below the Mott transition (polariton laser). In contrast to equilibrium Bose-Einstein condensates, the nonequilibrium driven-dissipative nature enables the population of higher orbitals if any confinement potential is present to induce enhanced quantum correlations. Trapping inside microwire spacers leads to a polariton harmonic oscillator resulting in discrete states in an equidistant ladder of photonic orbitals. Level occupation and selection of a specific wave function is managed via optical control, mimicking a quantum emitter on a macroscopic level. It shows that exotic states of matter can be realized in rather simple structures at room temperature directly visible to the human eye. It represents also an excellent opportunity to study basic many-body dynamics in one-dimensional bosonic matter by simultaneously settling an optimized fabrication technique for devices enabling practical Boolean quantum logic gates for optical computing.

  1. Room-temperature continuous-wave electrically injected InGaN-based laser directly grown on Si

    Science.gov (United States)

    Sun, Yi; Zhou, Kun; Sun, Qian; Liu, Jianping; Feng, Meixin; Li, Zengcheng; Zhou, Yu; Zhang, Liqun; Li, Deyao; Zhang, Shuming; Ikeda, Masao; Liu, Sheng; Yang, Hui

    2016-09-01

    Silicon photonics would greatly benefit from efficient, visible on-chip light sources that are electrically driven at room temperature. To fully utilize the benefits of large-scale, low-cost manufacturing foundries, it is highly desirable to grow direct bandgap III-V semiconductor lasers directly on Si. Here, we report the demonstration of a blue-violet (413 nm) InGaN-based laser diode grown directly on Si that operates under continuous-wave current injection at room temperature, with a threshold current density of 4.7 kA cm-2. The heteroepitaxial growth of GaN on Si is confronted with a large mismatch in both the lattice constant and the coefficient of thermal expansion, often resulting in a high density of defects and even microcrack networks. By inserting an Al-composition step-graded AlN/AlGaN multilayer buffer between the Si and GaN, we have not only successfully eliminated crack formation, but also effectively reduced the dislocation density. The result is the realization of a blue-violet InGaN-based laser on Si.

  2. Towards room temperature solid state quantum devices at the edge of quantum chaos for long-living quantum states

    Science.gov (United States)

    Prati, Enrico

    2015-07-01

    Long living coherent quantum states have been observed in biological systems up to room temperature. Light harvesting in chromophoresis realized by excitonic systems living at the edge of quantum chaos, where energy level distribution becomes semi-Poissonian. On the other hand, artificial materials suffer the loss of coherence of quantum states in quantum information processing, but semiconductor materials are known to exhibit quantum chaotic conditions, so the exploitation of similar conditions are to be considered. The advancements of nanofabrication, together with the control of implantation of individual atoms at nanometric precision, may open the experimental study of such special regime at the edge of the phase transitions for the electronic systems obtained by implanting impurity atoms in a silicon transistor. Here I review the recent advancements made in the field of theoretical description of the light harvesting in biological system in its connection with phase transitions at the few atoms scale and how it would be possible to achieve transition point to quantum chaotic regime. Such mechanism may thus preserve quantum coherent states at room temperature in solid state devices, to be exploited for quantum information processing as well as dissipation-free quantum electronics.

  3. Room-Temperature-Processable Wire-Templated Nano-Electrodes for Flexible and Transparent All-Wire Electronics.

    Science.gov (United States)

    Min, Sung-Yong; Lee, Yeongjun; Kim, Se Hyun; Park, Cheolmin; Lee, Tae-Woo

    2017-03-17

    Sophisticate preparation of arbitrarily-long conducting nanowire electrodes on large area is a significant requirement for development of transparent nano-electronics. We report position-customizable and room-temperature-processable metallic nanowire (NW) electrodes array using aligned NW templates and a demonstration of transparent all-NW-based electronic applications by simple direct-printing. Well-controlled electroless-plating chemistry on a polymer NW template provided a highly-conducting Au NW array with a very low resistivity of 7.5 μΩ cm (only 3.4 times higher than that of bulk Au), high optical transmittance (> 90%), and mechanical bending stability. This method enables fabrication of all-NW-based electronic devices on various non-planar surfaces and flexible plastic substrates. Our approach facilitates realization of advanced future electronics.

  4. Aging meat at room and cold temperatures on meat quality and aging loss of sheep carcass

    Directory of Open Access Journals (Sweden)

    Roswita Sunarlim

    2001-03-01

    Full Text Available The aim of this research is to compare the quality of meat of local carcass sheep between fresh and aging meat stored at room temperature for 12 hours, at 4oC for one day and one week. For that purpose a study of aging carcass involving 12 local sheep (male and female with different ages was carried out by separating carcass into two parts: (1 the right portion was aged on 4oC for one day and one week, room temperature for 12 hours, and (2 the left portion as control without aging. A factorial design 2x2 (2 sexes and aging vs without aging for three kinds of aging on quality of meat. A factorial design 2x3 (2 sexes and 3 kinds of aging on aging loss. Replicate twice was carried out with different ages (old and young sheep. Parameter measured were pH, warter-holding capacity, cooking loss, color, tenderness, carcass weight loss. There was decrease in pH, increase in tenderness value for aged meat that stored at room temperature for 12 hours (1.84 kg, at cold temperature for one day (2.03 kg, but tenderness value was the most (0.92 kg at cold temperature for one week compared to fresh meat (3.41, 4.06, and 3.66 kg. Lightness color (l, red color (a and yellow color (b for aged meat is usually increase compare to fresh meat, except for aged meat stored at room temperature for 12 hours was decrease significant. Water-holding capacity and cooking loss value of aged meat was not significant compared to fresh meat. Aging loss of aged meat stored at 4oC for one week (13.58% was significant compared to aged meat stored at room temperature (2.42% and 4oC for one day (2.90%.

  5. Functional relationship of room temperature and setting time of alginate impression material

    Directory of Open Access Journals (Sweden)

    Dyah Irnawati

    2009-09-01

    Full Text Available Background: Indonesia is a tropical country with temperature variation. A lot of dental clinics do not use air conditioner. The room temperature influences water temperature for mixing alginate impression materials. Purpose: The aim of this study was to investigate the functional relationship of room temperature and initial setting time of alginate impression materials. Methods: The New Kromopan® alginate (normal and fast sets were used. The initial setting time were tested at 23 (control, 24, 25, 26, 27, 28, 29, 30 and 31 degrees Celcius room temperatures (n = 5. The initial setting time was tested based on ANSI/ADA Specification no. 18 (ISO 1563. The alginate powder was mixed with distilled water (23/50 ratio, put in the metal ring mould, and the initial setting time was measured by test rod. Data were statistically analyzed by linear regression (α = 0.05. result: The initial setting times were 149.60 ± 0.55 (control and 96.40 ± 0.89 (31° C seconds for normal set, and 122.00 ± 1.00 (control and 69.60 ± 0.55 (31° C seconds for fast set. The coefficient of determination of room temperature to initial setting time of alginate were R2 = 0.74 (normal set and R2 = 0.88 (fast set. The regression equation for normal set was Y = 257.6 – 5.5 X (p < 0.01 and fast set was Y = 237.7 – 5.6 X (p < 0.01. Conclusions: The room temperature gave high contribution and became a strength predictor for initial setting time of alginates. The share contribution to the setting time was 0.74% for normal set and 0.88% for fast set alginates.

  6. Instantaneous room temperature bonding of a wide range of non-silicon substrates with poly(dimethylsiloxane) (PDMS) elastomer mediated by a mercaptosilane.

    Science.gov (United States)

    Wu, Wenming; Wu, Jing; Kim, Jae-Heon; Lee, Nae Yoon

    2015-07-07

    This paper introduces an instantaneous and robust strategy for bonding a variety of non-silicon substrates such as thermoplastics, metals, an alloy, and ceramics to poly(dimethylsiloxane) (PDMS) irreversibly, mediated by one-step chemical modification using a mercaptosilane at room temperature followed by corona treatment to realize heterogeneous assembly also at room temperature. The mercapto functional group is one of the strongest nucleophiles, and it can instantaneously react with electrophiles of substrates, resulting in an alkoxysilane-terminated substrate at room temperature. In this way, prior oxidation of the substrate is dispensed with, and the alkoxysilane-terminated substrate can be readily oxidized and irreversibly bonded with oxidized PDMS at room temperature. A commercially available Tesla coil was used for surface oxidation, replacing a bulky and expensive plasma generator. Surface characterization was conducted by water contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis. A total of fifteen non-silicon substrates including polycarbonate (PC), two types of poly(vinylchloride) (PVC), poly(methylmethacrylate) (PMMA), polystyrene (PS), polyimide (PI), two types of poly(ethylene terephthalate) (PET), polypropylene (PP), iron (Fe), aluminum (Al), copper (Cu), brass, alumina (Al2O3), and zirconia (ZrO2) were bonded successfully with PDMS using this method, and the bond strengths of PDMS-PMMA, PDMS-PC, PDMS-PVC, PDMS-PET, PDMS-Al, and PDMS-Cu assemblies were measured to be approximately 335.9, 511.4, 467.3, 476.4, 282.2, and 236.7 kPa, respectively. The overall processes including surface modification followed by surface oxidation using corona treatment for bonding were realized within 12 to 17 min for most of the substrates tested except for ceramics which required 1 h for the bonding. In addition, large area (10 × 10 cm(2)) bonding was also successfully realized, ensuring the high reliability and stability of the introduced

  7. Black Phosphorus Based Field Effect Transistors with Simultaneously Achieved Near Ideal Subthreshold Swing and High Hole Mobility at Room Temperature.

    Science.gov (United States)

    Liu, Xinke; Ang, Kah-Wee; Yu, Wenjie; He, Jiazhu; Feng, Xuewei; Liu, Qiang; Jiang, He; Dan Tang; Wen, Jiao; Lu, Youming; Liu, Wenjun; Cao, Peijiang; Han, Shun; Wu, Jing; Liu, Wenjun; Wang, Xi; Zhu, Deliang; He, Zhubing

    2016-04-22

    Black phosphorus (BP) has emerged as a promising two-dimensional (2D) material for next generation transistor applications due to its superior carrier transport properties. Among other issues, achieving reduced subthreshold swing and enhanced hole mobility simultaneously remains a challenge which requires careful optimization of the BP/gate oxide interface. Here, we report the realization of high performance BP transistors integrated with HfO2 high-k gate dielectric using a low temperature CMOS process. The fabricated devices were shown to demonstrate a near ideal subthreshold swing (SS) of ~69 mV/dec and a room temperature hole mobility of exceeding >400 cm(2)/Vs. These figure-of-merits are benchmarked to be the best-of-its-kind, which outperform previously reported BP transistors realized on traditional SiO2 gate dielectric. X-ray photoelectron spectroscopy (XPS) analysis further reveals the evidence of a more chemically stable BP when formed on HfO2 high-k as opposed to SiO2, which gives rise to a better interface quality that accounts for the SS and hole mobility improvement. These results unveil the potential of black phosphorus as an emerging channel material for future nanoelectronic device applications.

  8. Black Phosphorus Based Field Effect Transistors with Simultaneously Achieved Near Ideal Subthreshold Swing and High Hole Mobility at Room Temperature

    Science.gov (United States)

    Liu, Xinke; Ang, Kah-Wee; Yu, Wenjie; He, Jiazhu; Feng, Xuewei; Liu, Qiang; Jiang, He; Dan Tang; Wen, Jiao; Lu, Youming; Liu, Wenjun; Cao, Peijiang; Han, Shun; Wu, Jing; Liu, Wenjun; Wang, Xi; Zhu, Deliang; He, Zhubing

    2016-04-01

    Black phosphorus (BP) has emerged as a promising two-dimensional (2D) material for next generation transistor applications due to its superior carrier transport properties. Among other issues, achieving reduced subthreshold swing and enhanced hole mobility simultaneously remains a challenge which requires careful optimization of the BP/gate oxide interface. Here, we report the realization of high performance BP transistors integrated with HfO2 high-k gate dielectric using a low temperature CMOS process. The fabricated devices were shown to demonstrate a near ideal subthreshold swing (SS) of ~69 mV/dec and a room temperature hole mobility of exceeding >400 cm2/Vs. These figure-of-merits are benchmarked to be the best-of-its-kind, which outperform previously reported BP transistors realized on traditional SiO2 gate dielectric. X-ray photoelectron spectroscopy (XPS) analysis further reveals the evidence of a more chemically stable BP when formed on HfO2 high-k as opposed to SiO2, which gives rise to a better interface quality that accounts for the SS and hole mobility improvement. These results unveil the potential of black phosphorus as an emerging channel material for future nanoelectronic device applications.

  9. A new sensor for ammonia based on cyanidin-sensitized titanium dioxide film operating at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Xiao-wei, Huang [School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, 212013 Zhenjiang, Jiangsu (China); Xiao-bo, Zou, E-mail: zou_xiaobo@ujs.edu.cn [School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, 212013 Zhenjiang, Jiangsu (China); Key Laboratory of Modern Agricultural Equipment and Technology, 301 Xuefu Road, 212013 Zhenjiang, Jiangsu (China); Ji-yong, Shi; Jie-wen, Zhao; Yanxiao, Li [School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, 212013 Zhenjiang, Jiangsu (China); Limin, Hao; Jianchun, Zhang [The Research Center of China Hemp Materials, Beijing (China)

    2013-07-17

    Graphical abstract: -- Highlights: •TiO{sub 2} was prepared by sol–gel method film and then functionalized with the cyanidin dye. •The morphology and the absorption spectra of films were examined. •The hybrid organic–inorganic formed film here can detect ammonia reversibly at room temperature. •The low humidity could promote the sensitivity of the sensors. -- Abstract: Design and fabrication of an ammonia sensor operating at room temperature based on pigment-sensitized TiO{sub 2} films was described. TiO{sub 2} was prepared by sol–gel method and deposited on glass slides containing gold electrodes. Then, the film immersed in a 2.5 × 10{sup −4} M ethanol solution of cyanidin to absorb the pigment. The hybrid organic–inorganic formed film here can detect ammonia reversibly at room temperature. The relative change resistance of the films at a potential difference of 1.5 V is determined when the films are exposed to atmospheres containing ammonia vapors with concentrations over the range 10–50 ppm. The relative change resistance, S, of the films increased almost linearly with increasing concentrations of ammonia (r = 0.92). The response time to increasing concentrations of the ammonia is about 180–220 s, and the corresponding values for decreasing concentrations 240–270 s. At low humidity, ammonia could be ionized by the cyanidin on the TiO{sub 2} film and thereby decrease in the proton concentration at the surface. Consequently, more positively charged holes at the surface of the TiO{sub 2} have to be extracted to neutralize the adsorbed cyanidin and water film. The resistance response to ammonia of the sensors was nearly independent on temperature from 10 to 50 °C. These results are not actually as good as those reported in the literature, but this preliminary work proposes simpler and cheaper processes to realize NH{sub 3} sensor for room temperature applications.

  10. Climate control based on temperature measurement in the animal-occupied zone of a pig room with ground channel ventilation

    NARCIS (Netherlands)

    Wagenberg, van A.V.; Aerts, J.M.; Brecht, van A.; Vranken, E.; Leroy, T.; Berckmans, D.

    2005-01-01

    It is known that there can be a significant temperature difference between the position of the climate controller sensor (room temperature) and the animal-occupied zone (AOZ) in a pig room. This study explores the advantages of using AOZ temperature in climate control. The objectives were: (1) to ev

  11. Voiding generation in copper interconnect under room temperature storage in 12 years

    Science.gov (United States)

    Matsuyama, Hideya; Suzuki, Takashi; Nakamura, Tomoji; Shiozu, Motoki; Ehara, Hideo; Oshima, Masao; Soeda, Takeshi; Hosoi, Hirokazu; Yamabe, Kikuo

    2017-07-01

    We measured the internal residual stress change of ULSI copper interconnects at room temperature for 12 years to confirm the stress migration phenomenon. The residual stress decreased and voids were generated. Furthermore, we investigated the stress change results and void features obtained through physical analyses. The voids had the same features as those in the high-temperature storage. The estimated volume shrinkage agreed with the total volume of the observed voids, suggesting that void generation causes the decrease in stress. From the obtained result, we conclude that the stress migration degradation phenomenon occurs even at room temperature in the long-term storage, and that the void feature is almost identical to that in the high-temperature acceleration test.

  12. Topologically protected quantum transport in locally exfoliated bismuth at room temperature.

    Science.gov (United States)

    Sabater, C; Gosálbez-Martínez, D; Fernández-Rossier, J; Rodrigo, J G; Untiedt, C; Palacios, J J

    2013-04-26

    We report electrical conductance measurements of Bi nanocontacts created by repeated tip-surface indentation using a scanning tunneling microscope at temperatures of 4 and 300 K. As a function of the elongation of the nanocontact, we measure robust, tens of nanometers long plateaus of conductance G0 = 2e2/h at room temperature. This observation can be accounted for by the mechanical exfoliation of a Bi(111) bilayer, a predicted quantum spin Hall (QSH) insulator, in the retracing process following a tip-surface contact. The formation of the bilayer is further supported by the additional observation of conductance steps below G0 before breakup at both temperatures. Our finding provides the first experimental evidence of the possibility of mechanical exfoliation of Bi bilayers, the existence of the QSH phase in a two-dimensional crystal, and, most importantly, the observation of the QSH phase at room temperature.

  13. Extreme Sensitivity of Room-Temperature Photoelectric Effect for Terahertz Detection.

    Science.gov (United States)

    Huang, Zhiming; Zhou, Wei; Tong, Jinchao; Huang, Jingguo; Ouyang, Cheng; Qu, Yue; Wu, Jing; Gao, Yanqing; Chu, Junhao

    2016-01-01

    Extreme sensitivity of room-temperature photoelectric effect for terahertz (THz) detection is demonstrated by generating extra carriers in an electromagnetic induced well located at the semiconductor, using a wrapped metal-semiconductor-metal configuration. The excellent performance achieved with THz detectors shows great potential to open avenues for THz detection.

  14. Electroreduction of Benzoylformic Acid in 1-Ethyl-3-methylimidazolium Bromide Room Temperature Ionic Liquid

    Institute of Scientific and Technical Information of China (English)

    SUN Qian; ZHAO Peng; LU Jia-xing; HE Ming-yuan

    2005-01-01

    @@ Introduction The chemical industry is under considerable pressure to replace many volatile organic compounds that are widely used as solvents in organic synthesis. This trend leads to the exploration for novel reaction media. Room temperature ionic liquids as environmentally benign media for organic synthesis and catalytic reactions have been gradually recognized and accepted[1,2].

  15. Room-temperature electron spin amplifier based on Ga(In)NAs alloys.

    Science.gov (United States)

    Puttisong, Yuttapoom; Buyanova, Irina A; Ptak, Aaron J; Tu, Charles W; Geelhaar, Lutz; Riechert, Henning; Chen, Weimin M

    2013-02-06

    The first experimental demonstration of a spin amplifier at room temperature is presented. An efficient, defect-enabled spin amplifier based on a non-magnetic semiconductor, Ga(In)NAs, is proposed and demonstrated, with a large spin gain (up to 2700% at zero field) for conduction electrons and a high cut-off frequency of up to 1 GHz.

  16. Propane selective oxidation on alkaline earth exchanged zeolite Y: room temperature in situ IR study

    NARCIS (Netherlands)

    Xu, Jiang; Mojet, Barbara L.; Ommen, van Jan G.; Lefferts, Leon

    2003-01-01

    The effect of zeolite Y ion-exchanged with a series of alkaline-earth cations on selective propane oxidation at room temperature was studied with in situ infrared spectroscopy. Isopropylhydroperoxide was observed as a reaction intermediate and can be decomposed into acetone and water. Contrary to pr

  17. Yttrium Nitrate mediated Nitration of Phenols at room temperature in Glacial Acetic acid

    Indian Academy of Sciences (India)

    MOHABUL A MONDAL; DBASHIS MANDAL; KANCHAN MITRA

    2017-01-01

    Rapid nitration of electron rich phenols using Y(NO₃)₃.6H₂O in glacial acetic acid at room temperature was observed with good yield. The method allows nitration of phenols without oxidation, and isolation of nitration product in a rapid and simple way. The described method is selective for phenols.

  18. Velocity and Temperature Distribution in Flow from an Inlet Device in Rooms with Displacement Ventilation

    DEFF Research Database (Denmark)

    Jacobsen, T.V.; Nielsen, Peter V.

    Measurements are performed in a full-scale test room with displacement ventilation with focus on the velocity and temperature field in the region close to the inlet device. Investigations based on these detailed measurements have been made in order to see if it is possible to describe the velocity...

  19. Structure determination of an integral membrane protein at room temperature from crystals in situ

    Energy Technology Data Exchange (ETDEWEB)

    Axford, Danny [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Foadi, James [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Hu, Nien-Jen; Choudhury, Hassanul Ghani [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Iwata, So [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Kyoto University, Kyoto 606-8501 (Japan); Beis, Konstantinos [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom); Evans, Gwyndaf, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Alguel, Yilmaz, E-mail: gwyndaf.evans@diamond.ac.uk [Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE (United Kingdom); Imperial College London, London SW7 2AZ (United Kingdom); Rutherford Appleton Laboratory, Oxfordshire OX11 0FA (United Kingdom)

    2015-05-14

    The X-ray structure determination of an integral membrane protein using synchrotron diffraction data measured in situ at room temperature is demonstrated. The structure determination of an integral membrane protein using synchrotron X-ray diffraction data collected at room temperature directly in vapour-diffusion crystallization plates (in situ) is demonstrated. Exposing the crystals in situ eliminates manual sample handling and, since it is performed at room temperature, removes the complication of cryoprotection and potential structural anomalies induced by sample cryocooling. Essential to the method is the ability to limit radiation damage by recording a small amount of data per sample from many samples and subsequently assembling the resulting data sets using specialized software. The validity of this procedure is established by the structure determination of Haemophilus influenza TehA at 2.3 Å resolution. The method presented offers an effective protocol for the fast and efficient determination of membrane-protein structures at room temperature using third-generation synchrotron beamlines.

  20. CdO necklace like nanobeads decorated with PbS nanoparticles: Room temperature LPG sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sonawane, N.B. [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon, 425001 M.S. (India); K.A.M.P. & N.K.P. Science College, Pimpalner, Sakri, Dhule, M.S. (India); Baviskar, P.K. [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon, 425001 M.S. (India); Ahire, R.R. [S.G. Patil Science, Sakri, Dhule, M.S. (India); Sankapal, B.R., E-mail: brsankapal@gmail.com [Nano Materials and Device Laboratory, Department of Applied Physics, Visvesvaraya National Institute of Technology, South Ambazari Road, Nagpur, 440010 M.S. (India)

    2017-04-15

    Simple chemical route has been employed to grow interconnected nanobeads of CdO having necklace like structure through air annealing of cadmium hydroxide nanowires. This nanobeads of n-CdO with high surface area has been decorated with p-PbS nanoparticles resulting in the formation of nano-heterojunction which has been utilized effectively as room temperature liquefied petroleum gas (LPG) sensor. The room temperature gas response towards C{sub 2}H{sub 5}OH, Cl{sub 2}, NH{sub 3}, CO{sub 2} and LPG was investigated, among which LPG exhibits significant response. The maximum gas response of 51.10% is achieved with 94.54% stability upon exposure of 1176 ppm concentration of LPG at room temperature (27 °C). The resulting parameters like gas response, response and recovery time along with stability studies has been studied and results are discussed herein. - Highlights: • Conversion of Cd(OH){sub 2} nanowires to CdO nanonecklace by air annealing at 290 °C. • Decoration of PbS nanoparticles over CdO nanobeads by SILAR method. • Formation of n-CdO/p-PbS nano-heterojunction as room temperature LPG sensor. • Maximum gas response of 51.10% with 94.54% stability.

  1. Evolution of the microstructure in electrochemically deposited copper films at room temperature

    DEFF Research Database (Denmark)

    Pantleon, Karen; Somers, Marcel A. J.

    2007-01-01

    The room temperature evolution of the microstructure in copper electrodeposits (self-annealing) was investigated by means of X-ray diffraction analysis and simultaneous measurement of the electrical resistivity as a function of time with an unprecedented time resolution. Independent of the copper...

  2. Room-temperature diode-pumped Yb:KYF(4) laser.

    Science.gov (United States)

    Galzerano, Gianluca; Laporta, Paolo; Sani, Elisa; Bonelli, Lucia; Toncelli, Alessandra; Tonelli, Mauro; Pesatori, Alessandro; Svelto, Cesare

    2006-11-15

    Continuous-wave laser action has been demonstrated in a diode-pumped Yb:KYF(4) crystal. Crystal growth, spectroscopic measurements, and laser results are presented. A maximum output power of 505 mW, a slope efficiency of 43%, and a continuous wavelength tunability range of 65nm, from 1013 to 1078 nm, have been obtained at room temperature.

  3. Room-temperature 1.2-J Fe{sup 2+}:ZnSe laser

    Energy Technology Data Exchange (ETDEWEB)

    Velikanov, S D; Zaretsky, N A; Zotov, E A; Maneshkin, A A; Yutkin, I M [Russian Federal Nuclear Center ' All-Russian Research Institute of Experimental Physics' , Sarov, Nizhnii Novgorod region (Russian Federation); Kazantsev, S Yu; Kononov, I G; Firsov, K N [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Korostelin, Yu V; Frolov, M P [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2016-01-31

    The characteristics of a laser based on a Fe{sup 2+}:ZnSe single crystal pumped by an electric-discharge HF laser at room temperature are studied. The HF laser beam diameter on the crystal surface was 17 mm. The achieved laser energy was 1.2 J with an efficiency of ∼ 25% with respect to the pump energy. (letters)

  4. Room-temperature synthesis of soluble, fluorescent carbon nanoparticles from organogel precursors.

    Science.gov (United States)

    Néabo, Jules Roméo; Vigier-Carrière, Cécile; Rondeau-Gagné, Simon; Morin, Jean-François

    2012-10-18

    Carbon nanoparticles were obtained at room temperature by irradiating an organogel made from a 1,8-diaryloctatetrayne derivative in chloroform. During the topochemical polymerization, the morphology of the gel changes from fibers to soluble, yellow fluorescent nanoparticles in high yield. Analyses suggest that the resulting nanoparticles are made of amorphous graphitic carbon.

  5. Facile synthesis of gold nanoribbons by L-cysteine at room temperature

    Institute of Scientific and Technical Information of China (English)

    HUANG Lan; ZHANG Yu; GUO ZhiRui; GU Ning

    2009-01-01

    Highly crystalline gold nanoribbons have been synthesized via a simple method by L-cysteine reduc-tion of aqueous chloroaurate ions at room temperature, without additional capping agent or surfactant. Based on transmission electron microscopy (TEM) and UV-vis absorption studies for the intermediate products, the formation of gold nanoribbons is regarded as a kind of oriented attachment growth.

  6. Room Temperature Operation of a Buried Heterostructure Photonic Crystal Quantum Cascade Laser

    CERN Document Server

    Peretti, R; Wolf, J M; Bonzon, C; Süess, M J; Lourdudoss, S; Metaferia, W; Beck, M; Faist, J

    2015-01-01

    We demonstrated room temperature operation of deep etched photonic crystal quantum cascade laser emitting around 8.5 micron. We fabricated buried heterostructure photonic crystals, resulting in single mode laser emission on a high order slow Bloch modes of the photonic crystal, between high symmetry points of the Brillouin.

  7. Hydrophilicity Modification of Addition-cured Room Temperature Vulcanization Silicone Rubber

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Allyl terminated polyether was used to improve the hydrophilicity of addition-cured room temperature vulcanization silicone rubber. With the increasing of the polyether, both the hydrophilicity and water absorbed of the vulcanizates were increased. The mechanical properties were also improved by adding the polyether. The result showed that 1.5wt% of the polyether provided the silicone rubber with proper hydrophilicity.

  8. Room-temperature 1.2-J Fe2+:ZnSe laser

    Science.gov (United States)

    Velikanov, S. D.; Zaretsky, N. A.; Zotov, E. A.; Kazantsev, S. Yu; Kononov, I. G.; Korostelin, Yu V.; Maneshkin, A. A.; Firsov, K. N.; Frolov, M. P.; Yutkin, I. M.

    2016-01-01

    The characteristics of a laser based on a Fe2+:ZnSe single crystal pumped by an electric-discharge HF laser at room temperature are studied. The HF laser beam diameter on the crystal surface was 17 mm. The achieved laser energy was 1.2 J with an efficiency of ~ 25% with respect to the pump energy.

  9. Room-temperature synthesis of enantioenriched non-protected cyanohydrins using vanadium(salalen) catalyst.

    Science.gov (United States)

    Sakai, Yoshifumi; Mitote, Junko; Matsumoto, Kazuhiro; Katsuki, Tsutomu

    2010-08-21

    Room-temperature synthesis of enantioenriched non-protected cyanohydrins using acetone cyanohydrin as the cyanide source was achieved by V(salalen) catalyst. Aliphatic aldehydes underwent the cyanation with 89-95% ee in the presence of only 0.2-0.4 mol% catalyst. Aromatic cyanohydrins were also obtained in high enantiomeric excesses under modified conditions.

  10. Crystal induced phosphorescence from Benz(a)anthracene microcrystals at room temperature

    Science.gov (United States)

    Maity, Samir; Mazumdar, Prativa; Shyamal, Milan; Sahoo, Gobinda Prasad; Misra, Ajay

    2016-03-01

    Pure organic compounds that are also phosphorescent at room temperature are very rare in literature. Here, we report efficient phosphorescence emission from aggregated hydrosol of Benz(a)anthracene (BaA) at room temperature. Aggregated hydrosol of BaA has been synthesized by re-precipitation method and SDS is used as morphology directing agent. Morphology of the particles is characterized using optical and scanning electronic microcopy (SEM). Photophysical properties of the aggregated hydrosol are carried out using UV-vis, steady state and time resolved fluorescence study. The large stoke shifted structured emission from aggregated hydrosol of BaA has been explained due to phosphorescence emission of BaA at room temperature. In the crystalline state, the restricted intermolecular motions (RIM) such as rotations and vibrations are activated by crystal lattice. This rigidification effect makes the chromophore phosphorescent at room temperature. The possible stacking arrangement of the neighboring BaA within the aggregates has been substantiated by computing second order Fukui parameter as local reactivity descriptors. Computational study also reveals that the neighboring BaA molecules are present in parallel slipped conformation in its aggregated crystalline form.

  11. SQUID-magnetometer with open-ended horizontal room-temperature access

    NARCIS (Netherlands)

    Brake, ter H.J.M.; Ulfman, J.A.; Flokstra, J.

    1984-01-01

    A new, SQUID-based magnetometer has been developed for measurements of remanent and induced magnetisation. The advantage of this system compared to conventional SQUID-magnetometers is its horizontal access to the sensing coils. The access at room temperature is open at both ends. Main benefits of th

  12. Room-temperature near-field reflection spectroscopy of single quantum wells

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Hvam, Jørn Marcher; Madsen, Steen;

    1997-01-01

    . This technique suppresses efficiently the otherwise dominating far-field background and reduces topographic artifacts. We demonstrate its performance on a thin, strained near-surface CdS/ZnS single quantum well at room temperature. The optical structure of these topographically flat samples is due to Cd...

  13. Room-Temperature Palladium-Catalyzed Direct 2-Arylation of Benzoxazoles with Aryl and Heteroaryl Bromides†

    Science.gov (United States)

    Gao, Feng; Kim, Byeong-Seon; Walsh, Patrick J.

    2014-01-01

    An efficient room-temperature palladium-catalyzed direct 2-arylation of benzoxazoles with aryl bromides is presented. The Pd(OAc)2/NiXantphos-based catalyst enables the introduction of various aryl and heteroaryl groups, via a deprotonative cross-coupling process (DCCP) in good to excellent yields (75–99%). PMID:25078988

  14. Room-temperature base-free copper-catalyzed trifluoromethylation of organotrifluoroborates to trifluoromethylarenes

    KAUST Repository

    Huang, Yuanyuan

    2012-12-01

    An efficient room temperature copper-catalyzed trifluoromethylation of organotrifluoroborates under the base free condition using an electrophilic trifluoromethylating reagent is demonstrated. The corresponding trifluoromethylarenes were obtained in good to excellent yields and the reaction tolerates a wide range of functional groups. © 2012 Elsevier Ltd. All rights reserved.

  15. Room-Temperature Growth of Al Films on Si(111)-7×7 Surface

    Institute of Scientific and Technical Information of China (English)

    LIU Hong; ZHANG Yan-Feng; WANG De-Yong; JIA Jin-Feng; XUE Qi-Kun

    2004-01-01

    @@ Reflection high energy electron diffraction and scanning tunnelling microscopy (STM) are used to investigate the structure and morphology of Al films deposited on Si(111)-7 × 7 surface at room temperature. The films are polycrystalline, made up of (100) and (111) oriented islands, which primarily result from the interface elastic effect and free surface energies of the Al (100) and (111) surfaces.

  16. Quantum interference effects at room temperature in OPV-based single-molecule junctions

    DEFF Research Database (Denmark)

    Arroyo, Carlos R.; Frisenda, Riccardo; Moth-Poulsen, Kasper;

    2013-01-01

    Interference effects on charge transport through an individual molecule can lead to a notable modulation and suppression on its conductance. In this letter, we report the observation of quantum interference effects occurring at room temperature in single-molecule junctions based on oligo(3...

  17. International round robin test for mechanical properties of REBCO superconductive tapes at room temperature

    NARCIS (Netherlands)

    Osamura, K.; Shin, H.S.; Weiss, K.; Nyilas, A.; Nijhuis, A.; Yamamoto, K.; Machiya, S.; Nishijima, G.

    2014-01-01

    An international round robin test was promoted to establish a test method for room temperature mechanical properties of commercial REBCO superconductive tapes. Seven laboratories practiced a tensile test under the direction of guideline REBCO13 for four different kinds of REBCO tape. From the stress

  18. Determination of Trace Mercury by Catalytic Solid Substrate-room Temperature Phosphorimetry

    Institute of Scientific and Technical Information of China (English)

    Jia Ming LIU; Yun Xiong WU; Shao Xian LIN; Fei Ming LI; Xiu Mei SHI; Zhong Bin SHI; Guo Hui ZHU; Zhi Ming LI; Xiao Mei HUANG

    2006-01-01

    A new highly sensitive method (detection limit: 4.1 ag spot-1, sample volume: 0.4 μL spot-1) for the determination of trace Hg2+ by catalytic solid substrate-room temperature phosphorimetry has been established in this paper. This method has been successfully applied to determine trace Hg2+ in water.

  19. Copper-catalyzed Chan-Lam coupling between sulfonyl azides and boronic acids at room temperature.

    Science.gov (United States)

    Moon, Soo-Yeon; Nam, Jungsoo; Rathwell, Kris; Kim, Won-Suk

    2014-01-17

    A mild and efficient method for the synthesis of N-arylsulfonamides in the presence of 10 mol % of CuCl is demonstrated. The reaction proceeds readily at room temperature in an open flask using a variety of sulfonyl azides and boronic acids without any base, ligand, or additive.

  20. International round robin test for mechanical properties of REBCO superconductive tapes at room temperature

    NARCIS (Netherlands)

    Osamura, K.; Shin, H.S.; Weiss, K.; Nyilas, A.; Nijhuis, Arend; Yamamoto, K.; Machiya, S.; Nishijima, G.

    2014-01-01

    An international round robin test was promoted to establish a test method for room temperature mechanical properties of commercial REBCO superconductive tapes. Seven laboratories practiced a tensile test under the direction of guideline REBCO13 for four different kinds of REBCO tape. From the stress

  1. An Efficient Solid Acid Promoted Synthesis of Quinoxaline Derivatives at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    AHMAD,Shaabani; ALI,Maleki

    2007-01-01

    Quinoxaline derivatives have been synthesized in a very short time with excellent yields by the condensation of 1,2-diamines with aliphatic or aromatic 1,2-dicarbonyl compounds or benzilmonoxime in the presence of silica sul-furic acid as a very inexpensive solid acid catalyst at room temperature. The recovery and reuse of the catalyst are also satisfactory.

  2. Highly enantioselective rhodium-catalyzed conjugate addition of arylboronic acids to enones at room temperature

    NARCIS (Netherlands)

    Martina, SLX; Minnaard, AJ; Hessen, B; Feringa, BL; Martina, Sébastien L.X.; Feringa, Bernard

    2005-01-01

    The rhodium-phosphoramidite-catalyzed asymmetric conjugate addition of arylboronic acids to enones proceeds at room temperature using [Rh(OH)(cod)](2) or [RhCl(cod)](2)/KOH as stable and readily available catalyst precursors. (c) 2005 Published by Elsevier Ltd.

  3. GREEN SYNTHESIS OF SILVER AND PALLADIUM NANOPARTICLES AT ROOM TEMPERATURE USING COFFEE AND TEA EXTRACT

    Science.gov (United States)

    An extremely simple green approach that generates bulk quantities of nanocrystals of noble metals such as silver (Ag) and palladium (Pd) using coffee and tea extract at room temperature is described. The single-pot method uses no surfactant, capping agent, and/or template. The ob...

  4. How do polymerized room-temperature ionic liquid membranes plasticize during high pressure CO2 permeation?

    NARCIS (Netherlands)

    Simons, K.; Nijmeijer, D.C.; Bara, J.B.; Noble, R.D.; Wessling, M.

    2010-01-01

    Room-temperature ionic liquids (RTILs) are a class of organic solvents that have been explored as novel media for CO2 separations. Polymerized RTILs (poly(RTILs)) can be synthesized from RTIL monomers to form dense, solid gas selective membranes. It is of interest to understand the permeation proper

  5. Amorphous boron nanorod as an anode material for lithium-ion batteries at room temperature.

    Science.gov (United States)

    Deng, Changjian; Lau, Miu Lun; Barkholtz, Heather M; Xu, Haiping; Parrish, Riley; Xu, Meiyue Olivia; Xu, Tao; Liu, Yuzi; Wang, Hao; Connell, Justin G; Smith, Kassiopeia A; Xiong, Hui

    2017-08-03

    We report an amorphous boron nanorod anode material for lithium-ion batteries prepared through smelting non-toxic boron oxide in liquid lithium. Boron in theory can provide capacity as high as 3099 mA h g(-1) by alloying with Li to form B4Li5. However, experimental studies of the boron anode have been rarely reported for room temperature lithium-ion batteries. Among the reported studies the electrochemical activity and cycling performance of the bulk crystalline boron anode material are poor at room temperature. In this work, we utilized an amorphous nanostructured one-dimensional (1D) boron material aiming at improving the electrochemical reactivity between boron and lithium ions at room temperature. The amorphous boron nanorod anode exhibited, at room temperature, a reversible capacity of 170 mA h g(-1) at a current rate of 10 mA g(-1) between 0.01 and 2 V. The anode also demonstrated good rate capability and cycling stability. The lithium storage mechanism was investigated by both sweep voltammetry measurements and galvanostatic intermittent titration techniques (GITTs). The sweep voltammetric analysis suggested that the contributions from lithium ion diffusion into boron and the capacitive process to the overall lithium charge storage are 57% and 43%, respectively. The results from GITT indicated that the discharge capacity at higher potentials (>∼0.2 V vs. Li/Li(+)) could be ascribed to a capacitive process and at lower potentials (lithium-ion batteries.

  6. Achieving Room Temperature Orange Lasing Using InGaP/InAlGaP Diode Laser

    KAUST Repository

    Al-Jabr, A. A.

    2015-09-28

    We demonstrated the first orange laser diode at room temperature with a decent total output power of ∼46mW and lasing wavelength of 608nm, using a novel strain-induced quantum well intermixing in InGaP/InAlGaP red laser structure.

  7. LDA-Mediated Synthesis of Triarylmethanes by Arylation of Diarylmethanes with Fluoroarenes at Room Temperature.

    Science.gov (United States)

    Ji, Xinfei; Huang, Tao; Wu, Wei; Liang, Fang; Cao, Song

    2015-10-16

    A practical and convenient approach for the secondary C(sp(3))-H arylation of diarylmethanes with various fluoroarenes is described. The reaction proceeds smoothly in the presence of LDA (lithium diisopropylamide) at room temperature and affords triarylmethanes in moderate to high yields.

  8. Low Hydrogen Content Silicon Nitride Films Deposited at Room Temperature with an ECR Plasma Source

    NARCIS (Netherlands)

    Isai, Gratiela I.; Holleman, Jisk; Wallinga, Hans; Woerlee, Pierre H.

    2004-01-01

    Silicon nitride layers with very low hydrogen content (less than 1 atomic percent) were deposited at near room temperature, from N2 and SiH4, with a multipolar electron cyclotron resonance plasma. The influences of pressure and nitrogen flow rate on physical and electrical properties were studied in

  9. Spin Squeezing and Entanglement with Room Temperature Atoms for Quantum Sensing and Communication

    DEFF Research Database (Denmark)

    Shen, Heng

    magnetometer at room temperature is reported. Furthermore, using spin-squeezing of atomic ensemble, the sensitivity of magnetometer is improved. Deterministic continuous variable teleportation between two distant atomic ensembles is demonstrated. The fidelity of teleportating dynamically changing sequence...... of spin states surpasses a classical benchmark, demonstrating the true quantum teleportation....

  10. Experimental data of the static behavior of reinforced concrete beams at room and low temperature.

    Science.gov (United States)

    Mirzazadeh, M Mehdi; Noël, Martin; Green, Mark F

    2016-06-01

    This article provides data on the static behavior of reinforced concrete at room and low temperature including, strength, ductility, and crack widths of the reinforced concrete. The experimental data on the application of digital image correlation (DIC) or particle image velocimetry (PIV) in measuring crack widths and the accuracy and precision of DIC/PIV method with temperature variations when is used for measuring strains is provided as well.

  11. Synthesis, characterization and magnetic properties of room-temperature nanofluid ferromagnetic graphite

    OpenAIRE

    Souza, NS; Sergeenkov, S.; Speglich, C.; Rivera, VAG; Cardoso, CA; Pardo, H.; Mombru, AW; Rodrigues, AD; de Lima, OF; Araujo-Moreira, FM

    2009-01-01

    We report the chemical synthesis route, structural characterization, and physical properties of nanofluid magnetic graphite (NFMG) obtained from the previously synthesized bulk organic magnetic graphite (MG) by stabilizing the aqueous ferrofluid suspension with an addition of active cationic surfactant. The measured magnetization-field hysteresis curves along with the temperature dependence of magnetization confirmed room-temperature ferromagnetism in both MG and NFMG samples. (C) 2009 Americ...

  12. Room Temperature Oxide Deposition Approach to Fully Transparent, All-Oxide Thin-Film Transistors.

    Science.gov (United States)

    Rembert, Thomas; Battaglia, Corsin; Anders, André; Javey, Ali

    2015-10-28

    A room temperature cathodic arc deposition technique is used to produce high-mobility ZnO thin films for low voltage thin-film transistors (TFTs) and digital logic inverters. All-oxide, fully transparent devices are fabricated on alkali-free glass and flexible polyimide foil, exhibiting high performance. This provides a practical materials platform for the low-temperature fabrication of all-oxide TFTs on virtually any substrate.

  13. Room temperature Compton profiles of conduction electrons in -Ga metal

    Indian Academy of Sciences (India)

    B P Panda; N C Mohapatra

    2003-12-01

    Room temperature Compton profiles of momentum distribution of conduction electrons in -Ga metal are calculated in band model. For this purpose, the conduction electron wave functions are determined in a temperature-dependent non-local model potential. The profiles calculated along the crystallographic directions, (100), (010), and (001) are found to be nearly isotropic. This conclusion is in reasonable agreement with experimental observations.

  14. Experimental data of the static behavior of reinforced concrete beams at room and low temperature

    Directory of Open Access Journals (Sweden)

    M. Mehdi Mirzazadeh

    2016-06-01

    Full Text Available This article provides data on the static behavior of reinforced concrete at room and low temperature including, strength, ductility, and crack widths of the reinforced concrete. The experimental data on the application of digital image correlation (DIC or particle image velocimetry (PIV in measuring crack widths and the accuracy and precision of DIC/PIV method with temperature variations when is used for measuring strains is provided as well.

  15. Mirror thermal noise in laser interferometer gravitational wave detectors operating at room and cryogenic temperature

    CERN Document Server

    Franc, Janyce; Flaminio, Raffaele; Nawrodt, Ronny; Martin, Iain; Cunningham, Liam; Cumming, Alan; Rowan, Sheila; Hough, James

    2009-01-01

    Mirror thermal noise is and will remain one of the main limitations to the sensitivity of gravitational wave detectors based on laser interferometers. We report about projected mirror thermal noise due to losses in the mirror coatings and substrates. The evaluation includes all kind of thermal noises presently known. Several of the envisaged substrate and coating materials are considered. The results for mirrors operated at room temperature and at cryogenic temperature are reported.

  16. Facile Synthesis of Gold Nanoplates by Citrate Reduction of AuCl4- at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    Lan HUANG; Zhi Rui GUO; Meng WANG; Ning GU

    2006-01-01

    Single-crystalline, regular-edged gold nanoplates are synthesized through chemical reduction of AuCl4- by a suitable amount of citrate at room temperature, without additional capping agents or surfactants. The suitable molar ratio of sodium citrate to HAuCl4, low reaction temperature and the presence of natural light are critical factors for the formation of the regularly shaped nanoplates.

  17. Modelling the impact of room temperature on concentrations of polychlorinated biphenyls (PCBs) in indoor air

    DEFF Research Database (Denmark)

    Lyng, Nadja; Clausen, Per Axel; Lundsgaard, Claus

    2016-01-01

    Buildings contaminated with polychlorinated biphenyls (PCBs) are a health concern for the building occupants. Inhalation exposure is linked to indoor air concentrations of PCBs, which are known to be affected by indoor temperatures. In this study, a highly PCB contaminated room was heated to six....... The results showed that one easured concentration of PCB at a known steady-state temperature can be used to predict the steady-state concentrations at other temperatures under circumstances where e.g. direct sunlight does not influence temperatures and the air exchange rate is constant. The model was also...

  18. Infrared thermography evaluation from the back region of healthy horses in controlled temperature room

    Directory of Open Access Journals (Sweden)

    Mariana Pavelski

    2015-07-01

    Full Text Available The infrared thermography is a diagnostic imaging tool, which measures the surface temperature of an object through its heat emission. It is a non-invasive method, painless, with no involvement of radiation. Horses have elevated incidence of back injuries which causes decrease in their performance. A rapid and accurate diagnostic is essential to start the treatment. The aim of this paper was to establish the ideal time to the animal stay e inside a controlled room to balance their temperature and in the second time verify the thermographic temperature of specific back regions. It was studied fifteen healthy horses, being performed thermography of thoracic, lumbar and pelvic regions in four different times. There was a significant difference between the thermography performed outside and inside of the controlled temperature room. It was concluded that the ideal time to the horse stay into the controlled temperature room was thirty minutes and the mean thermographic temperatures of back regions, were obtained and can be used as parameters to identify injuries in other horses.

  19. Impact of Seasonal Variant Temperatures and Laboratory Room Ambient Temperature on Mortality of Rats with Ischemic Brain Injury

    Science.gov (United States)

    Gopalakrishanan, Sivakumar; Babu, Mg. Ramesh; Thangarajan, Rajesh; Punja, Dhiren; Jaganath, Vidyadhara Devarunda; Kanth, Akriti B.; Rao, Mohandas

    2016-01-01

    Introduction A popular rat model for hypoperfusion ischemic brain injury is bilateral common carotid artery occlusion (BCCAO). BCCAO surgery when performed in varying geographical locations and during different seasons of the year is reported to have variable mortality rates. Studies have also documented the diminishing influence of Ketamine-Xylazine (KT-XY) on thermoregulatory functions in rodents. Aim To explore the impact of seasonal variant temperatures and laboratory room ambient temperatures on mortality of rats following BCCAO surgery. Materials and Methods The study has two parts: 1 The first part is an analysis of a three year retrospective data to explore the association between the geographical season (hot summer and cold winter) induced laboratory room ambient temperature variations and the mortality rate in KT-XY anaesthetized BCCAO rats. 2. The second part investigated the effect of conditioned laboratory room ambient temperature (CAT) (23-250C) in KT-XY anaesthetized BCCAO group of rats. Rats were divided into 4 groups(n =8/group) as-Normal control, BCCAO and Sham BCCAO where they were all exposed to unconditioned ambient temperature (UCAT) during their surgery and postoperative care. And finally fourth group rats exposed to CAT during the BCCAO surgery and postoperative care. Results Pearson’s chi-square test indicates a significantly high association (p<0.006) between post-BCCAO mortality and hot season of the year. CAT during the hot season reduced the mortality rate (24% less) in post- BCCAO rats compared to the rats of UCAT. Conclusion Despite seasonal variations in temperature, conditioning the laboratory room ambient temperatures to 23–250C, induces hypothermia in KT-XY anaesthetized ischemic brain injured rodents and improves their survival rate. PMID:27190796

  20. Certification of NIST Room Temperature Low-Energy and High-Energy Charpy Verification Specimens.

    Science.gov (United States)

    Lucon, Enrico; McCowan, Chris N; Santoyo, Ray L

    2015-01-01

    The possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of -40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots considered, the observed variability was lower at 21 °C than at -40 °C. The results of this study will allow NIST to satisfy requests for room-temperature Charpy verification specimens that have been received from customers for several years: testing at 21 °C removes from the verification process the operator's skill in transferring the specimen in a timely fashion from the cooling bath to the impact position, and puts the focus back on the machine performance. For NIST, it also reduces the time and cost for certifying new verification lots. For one of the low-energy lots tested with a C-shaped hammer, we experienced two specimens jamming, which yielded unusually high values of absorbed energy. For both specimens, the signs of jamming were clearly visible. For all the low-energy lots investigated, jamming is slightly more likely to occur at 21 °C than at -40 °C, since at room temperature low-energy samples tend to remain in the test area after impact rather than exiting in the opposite direction of the pendulum swing. In the evaluation of a verification set, any jammed specimen should be removed from the analyses.

  1. Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

    Science.gov (United States)

    Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

    2016-08-10

    We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics.

  2. Giant electrocaloric effect in asymmetric ferroelectric tunnel junctions at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: liuyangphy52@gmail.com; Infante, Ingrid C.; Dkhil, Brahim, E-mail: brahim.dkhil@ecp.fr [Laboratoire Structures, Propriétés et Modélisation des Solides, UMR 8580 CNRS-Ecole Centrale Paris, Grande Voie des Vignes, Châtenay-Malabry Cedex 92295 (France); Lou, Xiaojie [Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, and State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2014-02-24

    Room-temperature electrocaloric properties of Pt/BaTiO{sub 3}/SrRuO{sub 3} ferroelectric tunnel junctions (FTJs) are studied by using a multiscale thermodynamic model. It is found that there is a divergence in the adiabatic temperature change ΔT for the two opposite polarization orientations. This difference under a typical writing voltage of 3 V can reach over 1 K as the barrier thickness decreases. Thanks to the ultrahigh external stimulus, a giant electrocaloric effect (1.53 K/V) with ΔT being over 4.5 K can be achieved at room temperature, which demonstrates the perspective of FTJs as a promising solid-state refrigeration.

  3. Room Temperature Ferromagnetic, Anisotropic, Germanium Rich FeGe(001 Alloys

    Directory of Open Access Journals (Sweden)

    Cristian M. Teodorescu

    2013-02-01

    Full Text Available Ferromagnetic FexGe1−x with x = 2%–9% are obtained by Fe deposition onto Ge(001 at high temperatures (500 °C. Low energy electron diffraction (LEED investigation evidenced the preservation of the (1 × 1 surface structure of Ge(001 with Fe deposition. X-ray photoelectron spectroscopy (XPS at Ge 3d and Fe 2p core levels evidenced strong Fe diffusion into the Ge substrate and formation of Ge-rich compounds, from FeGe3 to approximately FeGe2, depending on the amount of Fe deposited. Room temperature magneto-optical Kerr effect (MOKE evidenced ferromagnetic ordering at room temperature, with about 0.1 Bohr magnetons per Fe atom, and also a clear uniaxial magnetic anisotropy with the in-plane  easy magnetization axis. This compound is a good candidate for promising applications in the field of semiconductor spintronics.

  4. Noise-enhanced spontaneous chaos in semiconductor superlattices at room temperature

    Science.gov (United States)

    Alvaro, M.; Carretero, M.; Bonilla, L. L.

    2014-08-01

    Physical systems exhibiting fast spontaneous chaotic oscillations are used to generate high-quality true random sequences in random number generators. The concept of using fast practical entropy sources to produce true random sequences is crucial to make storage and transfer of data more secure at very high speeds. While the first high-speed devices were chaotic semiconductor lasers, the discovery of spontaneous chaos in semiconductor superlattices at room temperature provides a valuable nanotechnology alternative. Spontaneous chaos was observed in 1996 experiments at temperatures below liquid nitrogen. Here we show spontaneous chaos at room temperature appears in idealized superlattices for voltage ranges where sharp transitions between different oscillation modes occur. Internal and external noises broaden these voltage ranges and enhance the sensitivity to initial conditions in the superlattice snail-shaped chaotic attractor thereby rendering spontaneous chaos more robust.

  5. Room-temperature exciton-polaritons with two-dimensional WS$_2$

    CERN Document Server

    Flatten, Lucas C; Coles, David M; Trichet, Aurelien A P; Powell, Alex W; Taylor, Robert A; Warner, Jamie H; Smith, Jason M

    2016-01-01

    Two-dimensional transition metal dichalcogenides exhibit strong optical transitions with significant potential for optoelectronic devices. In particular they are suited for cavity quantum electrodynamics in which strong coupling leads to polariton formation as a root to realisation of inversionless lasing, polariton condensationand superfluidity. Demonstrations of such strongly correlated phenomena to date have often relied on cryogenic temperatures, high excitation densities and were frequently impaired by strong material disorder. At room-temperature, experiments approaching the strong coupling regime with transition metal dichalcogenides have been reported, but well resolved exciton-polaritons have yet to be achieved. Here we report a study of monolayer WS$_2$ coupled to an open Fabry-Perot cavity at room-temperature, in which polariton eigenstates are unambiguously displayed. In-situ tunability of the cavity length results in a maximal Rabi splitting of $\\hbar \\Omega_{\\rm{Rabi}} = 70$ meV, exceeding the e...

  6. Room temperature ferromagnetism in low dose ion implanted counter-doped Ge:Mn, As

    Science.gov (United States)

    Donarelli, M.; Kazakova, O.; Ortolani, L.; Morandi, V.; Impellizzeri, G.; Priolo, F.; Passacantando, M.; Ottaviano, L.

    2017-10-01

    We demonstrate room-temperature ferromagnetism in germanium counter-doped with manganese and arsenic at concentrations up to approximately 2.1 × 1020 at/cm3: these values are one order of magnitude lower than those at which ferromagnetic behavior has previously been observed. Synthesis proceeded by ion implantation at 513 K followed by annealing in argon at 673 K. High resolution TEM, STEM, and EDX show single-phase diamond cubic material lacking Mn or As precipitates. These findings are consistent with the prediction of Chen et al. that counter-doping with approximately equal concentrations of a single-electron donor permits Mn, a two-electron acceptor, to be incorporated at high enough concentrations to yield a diluted magnetic semiconductor with a Curie temperature above room temperature.

  7. Room temperature ferromagnetism in Fe-doped BaSnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Balamurugan, K.; Kumar, N. Harish [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Chelvane, J. Arout [Advanced Magnetics Group, Defense Metallurgical Research Laboratory, Hyderabad 500058 (India); Santhosh, P.N. [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)], E-mail: santhosh@iitm.ac.in

    2009-03-20

    Polycrystalline bulk samples of BaSn{sub 1-x}Fe{sub x}O{sub 3}, with x = 0.03, 0.04 and 0.05 were prepared by solid-state reaction method. These Fe-doped BaSnO{sub 3} systems exhibit ferromagnetism at room temperature with an average magnetic moment of 0.047, 0.038 and 0.025{mu}{sub B}/F{sub e} and Curie temperature of 510, 462 and 446 K, respectively. The observed magnetic properties are not attributed to any of the known impurity phases or clusters. The presence of ferromagnetic interaction at room temperature is supported by the ferromagnetic resonance (FMR) signals observed in the electron spin resonance spectra. The ferromagnetic order between Fe-ions is expected to be mediated by an electron trapped at the oxygen anion vacancy, called the F-centre exchange (FCE) interaction.

  8. A multi-layer zone model for predicting temperature distribution in a fire room

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiaojun; YANG Lizhong; DENG Zhihua; FAN Weicheng

    2004-01-01

    A multi-layer zone fire growth model is developed to predict the vertical distributions of the temperature in a single room. The fire room volume is divided into a number of horizontal layers, in which the temperature and other physical properties are assumed to be uniform. The principal equations for each laminated horizontal layer are derived from the conservation equations of mass and energy. The implemented fire sub-models are introduced, including the combustion, fluid flow and heat transfer models. Combined with these sub-models, the zone equations for the gas temperature of each layer are solved by Runge-Kutta method for each time step. The results of the sample calculations compare well with the results of experiments conducted by Steckler et al.

  9. Optically induced strong intermodal coupling in mechanical resonators at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, R.; Okamoto, H.; Yamaguchi, H. [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan); Hey, R.; Friedland, K. J. [Paul-Drude-Institut fur Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany)

    2015-08-31

    Strong parametric mode coupling in mechanical resonators is demonstrated at room temperature by using the photothermal effect in thin membrane structures. Thanks to the large stress modulation by laser irradiation, the coupling rate of the mechanical modes, defined as half of the mode splitting, reaches 2.94 kHz, which is an order of magnitude larger than electrically induced mode coupling. This large coupling rate exceeds the damping rates of the mechanical resonators and results in the strong coupling regime, which is a signature of coherent mode interaction. Room-temperature coherent mode coupling will enable us to manipulate mechanical motion at practical operation temperatures and provides a wide variety of applications of integrated mechanical systems.

  10. Room temperature strong light-matter coupling in three dimensional terahertz meta-atoms

    Science.gov (United States)

    Paulillo, B.; Manceau, J.-M.; Li, L. H.; Davies, A. G.; Linfield, E. H.; Colombelli, R.

    2016-03-01

    We demonstrate strong light-matter coupling in three dimensional terahertz meta-atoms at room temperature. The intersubband transition of semiconductor quantum wells with a parabolic energy potential is strongly coupled to the confined circuital mode of three-dimensional split-ring metal-semiconductor-metal resonators that have an extreme sub-wavelength volume (λ/10). The frequency of these lumped-element resonators is controlled by the size and shape of the external antenna, while the interaction volume remains constant. This allows the resonance frequency to be swept across the intersubband transition and the anti-crossing characteristic of the strong light-matter coupling regime to be observed. The Rabi splitting, which is twice the Rabi frequency (2ΩRabi), amounts to 20% of the bare transition at room temperature, and it increases to 28% at low-temperature.

  11. Fast diffusion in a room-temperature ionic liquid confined in mesoporous carbon

    Energy Technology Data Exchange (ETDEWEB)

    Mamontov, Eugene [ORNL; Wesolowski, David J [ORNL; Fulvio, Pasquale F [ORNL; Dai, Sheng [ORNL

    2012-01-01

    We report a quasielastic neutron scattering study in the temperature range of 290 to 350 K of a room temperature ionic liquid, [bmim+][Tf2N-], in the bulk form and confined in the 8.8 2.1 nm diameter pores of a mesoporous carbon matrix. In both bulk and confined liquids, our measurements, which are sensitive to the dynamics of the hydrogen-bearing cations, detect two distinct relaxation processes related to the diffusion of the cations. We have found that the cations that do not become immobilized near the pore walls exhibit an enhanced rather than suppressed diffusivity compared to the cation diffusivity in bulk liquid. Our results provide first experimental observation of molecular diffusion in a room temperature ionic liquid in confinement which is faster than diffusion in the bulk liquid.

  12. Solid state synthesis and room temperature magnetic properties of iron phosphide nanoparticles

    Science.gov (United States)

    Singh, N.; Khanna, P. K.; Joy, P. A.

    2009-02-01

    Room temperature magnetic properties have been achieved for nano-crystalline iron phosphide synthesized from the direct solid state reaction of iron chloride and tri-octylphosphine (TOP). The magnetization continuously increased with higher magnetic fields, indicating a super-paramagnetic behavior. It is observed that room temperature magnetism is possible for the material showing antiferromagnetic nature at low temperatures. In the present synthesis, TOP acted as a source of phosphorus as well as a surfactant. X-ray diffraction (XRD) studies revealed that the black powder is a mixture of FeP and Fe2P. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed elongated as well spherical particles. Energy dispersion X-ray analysis (EDAX) confirmed a non-stoichiometric iron phosphide. Presence of TOP was confirmed by infra-red (IR) spectroscopy, and thermo-gravimetric analysis (TGA) indicated about 6% wt. loss due to presence of organics.

  13. A general route toward complete room temperature processing of printed and high performance oxide electronics.

    Science.gov (United States)

    Baby, Tessy T; Garlapati, Suresh K; Dehm, Simone; Häming, Marc; Kruk, Robert; Hahn, Horst; Dasgupta, Subho

    2015-03-24

    Critical prerequisites for solution-processed/printed field-effect transistors (FETs) and logics are excellent electrical performance including high charge carrier mobility, reliability, high environmental stability and low/preferably room temperature processing. Oxide semiconductors can often fulfill all the above criteria, sometimes even with better promise than their organic counterparts, except for their high process temperature requirement. The need for high annealing/curing temperatures renders oxide FETs rather incompatible to inexpensive, flexible substrates, which are commonly used for high-throughput and roll-to-roll additive manufacturing techniques, such as printing. To overcome this serious limitation, here we demonstrate an alternative approach that enables completely room-temperature processing of printed oxide FETs with device mobility as large as 12.5 cm(2)/(V s). The key aspect of the present concept is a chemically controlled curing process of the printed nanoparticle ink that provides surprisingly dense thin films and excellent interparticle electrical contacts. In order to demonstrate the versatility of this approach, both n-type (In2O3) and p-type (Cu2O) oxide semiconductor nanoparticle dispersions are prepared to fabricate, inkjet printed and completely room temperature processed, all-oxide complementary metal oxide semiconductor (CMOS) invertors that can display significant signal gain (∼18) at a supply voltage of only 1.5 V.

  14. Design and Development of a Relative Humidity and Room Temperature Measurement System with On Line Data Logging Feature for Monitoring the Fermentation Room of Tea Factory

    Directory of Open Access Journals (Sweden)

    Utpal SARMA

    2011-12-01

    Full Text Available The design and development of a Relative Humidity (RH and Room Temperature (RT monitoring system with on line data logging feature for monitoring fermentation room of a tea factory is presented in this paper. A capacitive RH sensor with on chip signal conditioner is taken as RH sensor and a temperature to digital converter (TDC is used for ambient temperature monitoring. An 8051 core microcontroller is the heart of the whole system which reads the digital equivalent of RH data with the help of a 12-bit Analog to Digital (A/D converter and synchronize TDC to get the ambient temperature. The online data logging is achieved with the help of RS-232C communication. Field performance is also studied by installing it in the fermentation room of a tea factory.

  15. Dual gas-diffusion membrane- and mediatorless dihydrogen/air-breathing biofuel cell operating at room temperature

    Science.gov (United States)

    Xia, Hong-qi; So, Keisei; Kitazumi, Yuki; Shirai, Osamu; Nishikawa, Koji; Higuchi, Yoshiki; Kano, Kenji

    2016-12-01

    A membraneless direct electron transfer (DET)-type dihydrogen (H2)/air-breathing biofuel cell without any mediator was constructed wherein bilirubin oxidase from Myrothecium verrucaria (BOD) and membrane-bound [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F (MBH) were used as biocatalysts for the cathode and the anode, respectively, and Ketjen black-modified water proof carbon paper (KB/WPCC) was used as an electrode material. The KB/WPCC surface was modified with 2-aminobenzoic acid and p-phenylenediamine, respectively, to face the positively charged electron-accepting site of BOD and the negatively charged electron-donating site of MBH to the electrode surface. A gas-diffusion system was employed for the electrodes to realize high-speed substrate supply. As result, great improvement in the current density of O2 reduction with BOD and H2 reduction with MBH were realized at negatively and postively charged surfaces, respectively. Gas diffusion system also suppressed the oxidative inactivation of MBH at high electrode potentials. Finally, based on the improved bioanode and biocathode, a dual gas-diffusion membrane- and mediatorless H2/air-breathing biofuel cell was constructed. The maximum power density reached 6.1 mW cm-2 (at 0.72 V), and the open circuit voltage was 1.12 V using 1 atm of H2 gas as a fuel at room temperature and under passive and quiescent conditions.

  16. Differential solubility of ethylene and acetylene in room-temperature ionic liquids: a theoretical study.

    Science.gov (United States)

    Zhao, Xu; Xing, Huabin; Yang, Qiwei; Li, Rulong; Su, Baogen; Bao, Zongbi; Yang, Yiwen; Ren, Qilong

    2012-04-05

    The room-temperature ionic liquids (RTILs) have potential in realizing the ethylene (C(2)H(4)) and acetylene (C(2)H(2)) separation and avoiding solvent loss and environmental pollution compared with traditional solvents. The interaction mechanisms between gases and RTILs are important for the exploration of new RTILs for gas separation; thus, they were studied by quantum chemical calculation and molecular dynamics simulation in this work. The optimized geometries were obtained for the complexes of C(2)H(4)/C(2)H(2) with anions (Tf(2)N(-), BF(4)(-), and OAc(-)), cation (bmim(+)), and their ion pairs, and the analysis for geometry, interaction energy, natural bond orbital (NBO), and atoms in molecules (AIM) was performed. The quantum chemical calculation results show that the hydrogen-bonding interaction between the gas molecule and anion is the dominant factor in determining the solubility of C(2)H(2) in RTILs. However, the hydrogen-bonding interaction, the p-π interaction in C(2)H(4)-anion, and the π-π interaction in C(2)H(4)-cation are weak and comparable, which all affect the solubility of C(2)H(4) in RTILs with comparable contribution. The calculated results for the distance of H(gas)···X (X = O or F in anions), the BSSE-corrected interaction energy, the electron density of H(gas)···X at the bond critical point (ρ(BCP)), and the relative second-order perturbation stabilization energy (E(2)) are consistent with the experimental data that C(2)H(2) is more soluble than C(2)H(4) in the same RTILs and the solubility of C(2)H(4) in RTILs has the following order: [bmim][Tf(2)N] > [bmim][OAc] > [bmim][BF(4)]. The calculated results also agree with the order of C(2)H(2) solubility in different RTILs that [bmim][OAc] > [bmim][BF(4)] > [bmim][Tf(2)N]. Furthermore, the calculation results indicate that there is strong C(2)H(2)-RTIL interaction, which cannot be negligible compared to the RTIL-RTIL interaction; thus, the regular solution theory is probably not

  17. Ferromagnetism from Co-Doped ZnO Nanocantilevers above Room Temperature

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shao-Min; WANG Peng; LI Sheng; ZHANG Bin; GONG He-Chun; DU Zu-Liang

    2008-01-01

    @@ At low temperature (400° C), chemical vapour deposition (CVD) is employed to make comb-like Co-doped ZnO nanocantilever arrays (NAs). The magnetization curves of the as-synthesized Co-doped ZnO NAs indicate the existence of above-room-temperature ferromagnetism (ARTFM) (Curie temperature, Tc > 300 K) whereas un-doped ZnO NAs does not. The corresponding ferromagnetic source mechanism is discussed, in which defects play an important role due to the strong green light emission.

  18. Epitaxy of nanocrystalline silicon carbide on Si(111) at room temperature.

    Science.gov (United States)

    Verucchi, Roberto; Aversa, Lucrezia; Nardi, Marco V; Taioli, Simone; a Beccara, Silvio; Alfè, Dario; Nasi, Lucia; Rossi, Francesca; Salviati, Giancarlo; Iannotta, Salvatore

    2012-10-24

    Silicon carbide (SiC) has unique chemical, physical, and mechanical properties. A factor strongly limiting SiC-based technologies is the high-temperature synthesis. In this work, we provide unprecedented experimental and theoretical evidence of 3C-SiC epitaxy on silicon at room temperature by using a buckminsterfullerene (C(60)) supersonic beam. Chemical processes, such as C(60) rupture, are activated at a precursor kinetic energy of 30-35 eV, far from thermodynamic equilibrium. This result paves the way for SiC synthesis on polymers or plastics that cannot withstand high temperatures.

  19. Correcting for Microbial Blooms in Fecal Samples during Room-Temperature Shipping

    Science.gov (United States)

    Amir, Amnon; McDonald, Daniel; Navas-Molina, Jose A.; Debelius, Justine; Morton, James T.; Hyde, Embriette; Robbins-Pianka, Adam

    2017-01-01

    ABSTRACT The use of sterile swabs is a convenient and common way to collect microbiome samples, and many studies have shown that the effects of room-temperature storage are smaller than physiologically relevant differences between subjects. However, several bacterial taxa, notably members of the class Gammaproteobacteria, grow at room temperature, sometimes confusing microbiome results, particularly when stability is assumed. Although comparative benchmarking has shown that several preservation methods, including the use of 95% ethanol, fecal occult blood test (FOBT) and FTA cards, and Omnigene-GUT kits, reduce changes in taxon abundance during room-temperature storage, these techniques all have drawbacks and cannot be applied retrospectively to samples that have already been collected. Here we performed a meta-analysis using several different microbiome sample storage condition studies, showing consistent trends in which specific bacteria grew (i.e., “bloomed”) at room temperature, and introduce a procedure for removing the sequences that most distort analyses. In contrast to similarity-based clustering using operational taxonomic units (OTUs), we use a new technique called “Deblur” to identify the exact sequences corresponding to blooming taxa, greatly reducing false positives and also dramatically decreasing runtime. We show that applying this technique to samples collected for the American Gut Project (AGP), for which participants simply mail samples back without the use of ice packs or other preservatives, yields results consistent with published microbiome studies performed with frozen or otherwise preserved samples. IMPORTANCE In many microbiome studies, the necessity to store samples at room temperature (i.e., remote fieldwork) and the ability to ship samples without hazardous materials that require special handling training, such as ethanol (i.e., citizen science efforts), is paramount. However, although room-temperature storage for a few days has

  20. Room-temperature negative differential resistance in AlAs/ErAs/AlAs heterostructures grown on (001)GaAs

    Science.gov (United States)

    Tanaka, M.; Tsuda, M.; Nishinaga, T.; Palmstrøm, C. J.

    1996-01-01

    We have fabricated resonant tunneling structures having a buried ErAs semimetallic quantum well and AlAs double barriers, on (001)GaAs substrates. In order to suppress the three-dimensional island growth of GaAs and AlAs on ErAs and to obtain flat interfaces, we adopted a template approach, in which one monolayer of Mn was deposited on ErAs prior to the growth of AlAs, in molecular beam epitaxy. In the current-voltage characteristics at room temperature, negative differential resistance was clearly observed in a significant number of diodes with the ErAs thickness ranging from 2.6 to 5.0 nm. This room-temperature device operation on (001) substrates is, we believe, an important step towards the realization of semimetal/semiconductor hybrid quantum devices.

  1. Highly Sensitive Rayleigh Wave Hydrogen Sensors with WO3 Sensing Layers at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    WANG Cheng; FAN Li; ZHANG Shu-Yi; YANG Yue-Tao; ZHOU Ding-Mao; SHUI Xiu-Ji

    2011-01-01

    Rayleigh wave hydrogen sensors based on 128° YX-LiNbO3 substrates with WO3 sensing layers operating at room temperature are studied.The experimental results indicate that the WO3 layers obtained by a sol-gel method have much higher sensitivities because the sensing layers produced by the sol-gel method have small grains and high roughness and porosity.It is also confirmed that in the sol-gel method,keeping WO3 solutions at low temperature and/or decreasing the viscosity of the solutions can decrease the grain sizes and increase the hydrogen-absorbability of the sensing layer.Under the optimized preparation conditions,the high sensitivity of the hydrogen sensors at room temperature is obtained,in which 1% hydrogen in natural air induces the frequency shift of 72 kHz at the operating frequency of 124.2 MHz.Surface acoustic wave (SAW) hydrogen sensors have attracted a great deal of attention so far,in which the sensors have achieved high sensitivity as the sensors were often operated at high temperature,such as higher than 100℃.[1-4] However,in these experiments,a heater and a thermostat were required,which induced the sensors to be more complicated and unfavorable for miniaturization,and limited their application at room temperature.Furthermore,the heater can induce extra power loss and risks of fire and explosion.%Rayleigh wave hydrogen sensors based on 128° YX-LiNbO3 substrates with WO3 sensing layers operating at room temperature are studied. The experimental results indicate that the WO3 layers obtained by a sol-gel method have much higher sensitivities because the sensing layers produced by the sol-gel method have small grains and high roughness and porosity. It is also confirmed that in the sol-gel method, keeping WO3 solutions at low temperature and/or decreasing the viscosity of the solutions can decrease the grain sizes and increase the hydrogen-absorbability of the sensing layer. Under the optimized preparation conditions, the high sensitivity of the

  2. Characterization of CaWO{sub 4} scintillator at room and liquid nitrogen temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Moszynski, M. [Soltan Institute for Nuclear Studies, PL 05-400 Otwock-Swierk (Poland)]. E-mail: marek@ipj.gov.pl; Balcerzyk, M. [Soltan Institute for Nuclear Studies, PL 05-400 Otwock-Swierk (Poland); Czarnacki, W. [Soltan Institute for Nuclear Studies, PL 05-400 Otwock-Swierk (Poland); Nassalski, A. [Soltan Institute for Nuclear Studies, PL 05-400 Otwock-Swierk (Poland); Szczesniak, T. [Soltan Institute for Nuclear Studies, PL 05-400 Otwock-Swierk (Poland); Kraus, H. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Mikhailik, V.B. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Solskii, I.M. [Institute of Materials SRC ' Carat' , Lviv 790031 (Ukraine)

    2005-11-21

    The properties of CaWO{sub 4} (CaWO) crystals in {gamma}-spectrometry were studied at room and liquid nitrogen(LN{sub 2}) temperatures. Two small samples of 10x10x4 mm{sup 3} and 10x10x8 mm{sup 3} size were tested, coupled to a Photonis XP3212 photomultiplier at room temperature and a large area avalanche photodiode at LN{sub 2} temperature. Light pulse shape and light output at room and LN{sub 2} temperatures were measured. Energy resolution and non-proportionality of the CaWO response versus {gamma}-ray energy were studied and compared with those of small BGO and CdWO{sub 4} crystals to discuss further the origin of the intrinsic resolution of undoped scintillating crystals. A high light output of 4800{+-}200 phe/MeV and a good energy resolution of 6.6{+-}0.2% for 662 keV {gamma}-rays from a {sup 137}Cs source were measured for the small samples coupled to the XP3212 photomultiplier.

  3. Synthesis and characterization of nano crystalline nickel zinc ferrite for chlorine gas sensor at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, C. S., E-mail: charudutta-p@yahoo.com [Material Science and Thin Film Research Laboratory, Department of Physics,Shankarrao Mohite Mahavidyalaya, Akluj India (India); Gujar, M. P. [Shri. Shivaji Junior College, Bawada, Dist: Pune (India); Mathe, V. L. [Department of Physics, University of Pune, Pune – 411 007 India (India)

    2015-06-24

    Nano crystalline Nickel Zinc ferrite (Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4}) thin films were synthesized by Sol Gel method for gas response. The phase and microstructure of the obtained Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The nanostructured Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film shows single spinel phase. Magnetic study was obtained with the help of VSM. The effects of working temperature on the gas response were studied. The results reveal that the Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film gas sensor shows good selectivity to chlorine gas at room temperature. The sensor shows highest sensitivity (∼50%) at room temperature, indicating its application in detecting chlorine gas at room temperature in the future.

  4. High performance hydrogen storage from Be-BTB metal-organic framework at room temperature.

    Science.gov (United States)

    Lim, Wei-Xian; Thornton, Aaron W; Hill, Anita J; Cox, Barry J; Hill, James M; Hill, Matthew R

    2013-07-09

    The metal-organic framework beryllium benzene tribenzoate (Be-BTB) has recently been reported to have one of the highest gravimetric hydrogen uptakes at room temperature. Storage at room temperature is one of the key requirements for the practical viability of hydrogen-powered vehicles. Be-BTB has an exceptional 298 K storage capacity of 2.3 wt % hydrogen. This result is surprising given that the low adsorption enthalpy of 5.5 kJ mol(-1). In this work, a combination of atomistic simulation and continuum modeling reveals that the beryllium rings contribute strongly to the hydrogen interaction with the framework. These simulations are extended with a thermodynamic energy optimization (TEO) model to compare the performance of Be-BTB to a compressed H2 tank and benchmark materials MOF-5 and MOF-177 in a MOF-based fuel cell. Our investigation shows that none of the MOF-filled tanks satisfy the United States Department of Energy (DOE) storage targets within the required operating temperatures and pressures. However, the Be-BTB tank delivers the most energy per volume and mass compared to the other material-based storage tanks. The pore size and the framework mass are shown to be contributing factors responsible for the superior room temperature hydrogen adsorption of Be-BTB.

  5. Observation of room temperature ferromagnetism in pure La{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Qiang; Gao, Daqiang; Zhang, Jing; Yang, Zhaolong; Zhang, Zhipeng; Rao, Jinwei; Xue, Desheng [Lanzhou University, Key Laboratory for Magnetism and Magnetic Materials of MOE, Lanzhou (China)

    2014-09-15

    In this paper, we report the observation of intrinsic room temperature ferromagnetism in pure La{sub 2}O{sub 3} nanoparticles. Magnetism measurement indicates that all of the samples exhibit room temperature ferromagnetism and the saturation magnetization for the samples decreases with the increase in annealing temperature from 700 to 1,000 C. X-ray photoelectron spectroscopy identifies the presence of oxygen vacancies in the La{sub 2}O{sub 3} nanoparticles. The fitting results of the O 1s spectrum indicate that the variation of the oxygen vacancy concentration is in complete agreement with the change of the saturation magnetization. It is also found that the saturation magnetization of the La{sub 2}O{sub 3} nanoparticles can be tuned by post-annealing in argon or oxygen atmosphere. These results suggest that the oxygen vacancies are largely responsible for the room temperature ferromagnetism in pure La{sub 2}O{sub 3} nanoparticles. (orig.)

  6. Halide-stabilized LiBH4, a room-temperature lithium fast-ion conductor.

    Science.gov (United States)

    Maekawa, Hideki; Matsuo, Motoaki; Takamura, Hitoshi; Ando, Mariko; Noda, Yasuto; Karahashi, Taiki; Orimo, Shin-ichi

    2009-01-28

    Solid state lithium conductors are attracting much attention for their potential applications to solid-state batteries and supercapacitors of high energy density to overcome safety issues and irreversible capacity loss of the currently commercialized ones. Recently, we discovered a new class of lithium super ionic conductors based on lithium borohydride (LiBH(4)). LiBH(4) was found to have conductivity as high as 10(-2) Scm(-1) accompanied by orthorhombic to hexagonal phase transition above 115 degrees C. Polarization to the lithium metal electrode was shown to be extremely low, providing a versatile anode interface for the battery application. However, the high transition temperature of the superionic phase has limited its applications. Here we show that a chemical modification of LiBH(4) can stabilize the superionic phase even below room temperature. By doping of lithium halides, high conductivity can be obtained at room temperature. Both XRD and NMR confirmed room-temperature stabilization of superionic phase for LiI-doped LiBH(4). The electrochemical measurements showed a great advantage of this material as an extremely lightweight lithium electrolyte for batteries of high energy density. This material will open alternative opportunities for the development of solid ionic conductors other than previously known lithium conductors.

  7. Room temperature femtosecond X-ray diffraction of photosystem II microcrystals

    Science.gov (United States)

    Kern, Jan; Alonso-Mori, Roberto; Hellmich, Julia; Tran, Rosalie; Hattne, Johan; Laksmono, Hartawan; Glöckner, Carina; Echols, Nathaniel; Sierra, Raymond G.; Sellberg, Jonas; Lassalle-Kaiser, Benedikt; Gildea, Richard J.; Glatzel, Pieter; Grosse-Kunstleve, Ralf W.; Latimer, Matthew J.; McQueen, Trevor A.; DiFiore, Dörte; Fry, Alan R.; Messerschmidt, Marc; Miahnahri, Alan; Schafer, Donald W.; Seibert, M. Marvin; Sokaras, Dimosthenis; Weng, Tsu-Chien; Zwart, Petrus H.; White, William E.; Adams, Paul D.; Bogan, Michael J.; Boutet, Sébastien; Williams, Garth J.; Messinger, Johannes; Sauter, Nicholas K.; Zouni, Athina; Bergmann, Uwe; Yano, Junko; Yachandra, Vittal K.

    2012-01-01

    Most of the dioxygen on earth is generated by the oxidation of water by photosystem II (PS II) using light from the sun. This light-driven, four-photon reaction is catalyzed by the Mn4CaO5 cluster located at the lumenal side of PS II. Various X-ray studies have been carried out at cryogenic temperatures to understand the intermediate steps involved in the water oxidation mechanism. However, the necessity for collecting data at room temperature, especially for studying the transient steps during the O–O bond formation, requires the development of new methodologies. In this paper we report room temperature X-ray diffraction data of PS II microcrystals obtained using ultrashort (X-ray pulses from a hard X-ray free electron laser, namely the Linac Coherent Light Source. The results presented here demonstrate that the ”probe before destroy” approach using an X-ray free electron laser works even for the highly-sensitive Mn4CaO5 cluster in PS II at room temperature. We show that these data are comparable to those obtained in synchrotron radiation studies as seen by the similarities in the overall structure of the helices, the protein subunits and the location of the various cofactors. This work is, therefore, an important step toward future studies for resolving the structure of the Mn4CaO5 cluster without any damage at room temperature, and of the reaction intermediates of PS II during O–O bond formation. PMID:22665786

  8. Room temperature ferromagnetism in Mn-doped NiO nanoparticles

    Science.gov (United States)

    Layek, Samar; Verma, H. C.

    2016-01-01

    Mn-doped NiO nanoparticles of the series Ni1-xMnxO (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum.

  9. Avoiding hypothermia in neonatal pigs: effect of duration of floor heating at different room temperatures.

    Science.gov (United States)

    Pedersen, L J; Malmkvist, J; Kammersgaard, T; Jørgensen, E

    2013-01-01

    The effect of different farrowing room temperatures (15, 20, or 25°C), combined with floor heating (FH) at the birth site, on the postnatal rectal temperature of pigs, use of creep area, and latency to first colostrum uptake was investigated with 61 litters born by loose-housed sows. Pig rectal temperature was measured at birth, as well as at 0.25, 0.5, 1, 1.5, 2, 3, 4, 12, 24, and 48 h after birth. The drop in rectal temperature from birth to 0.5 h postpartum was less (Ptemperature of 25°C compared with 20 and 15°C. Minimum rectal temperature was less (Ptemperature to increase above 37°C was longer (Ptemperature was 15°C than 20 and 25°C. Rectal temperatures at 24 (Ptemperature of 15°C than 20 and 25°C. Duration of FH (12 or 48 h) did not influence (P>0.28) the rectal temperature at 24 or 48 h after birth. More pigs used the creep area 12 to 60 h after birth of the first pig at a room temperature of 15°C with 12 h FH compared with all other treatments. During the latter part of this period, more pigs stayed in the creep area also at 20°C with 12 h FH. After 60 h, more pigs (Plow compared with high room temperatures (15°C>20°C>25°C). Odds ratio of pigs dying before they had suckled was 6.8 times greater (P=0.03) at 15 than 25°C (95% CI of 1.3 to 35.5), whereas the odds ratio of dying during the first 7 d was 1.6 greater (P=0.05) for 48 vs. 12 h of FH (95% CI of 1.0 to 2.57), mainly due to more pigs being crushed. In conclusion, FH for 48 h was no more favorable than 12 h for pigs because the risk of hypothermia was equal in the 2 treatments, and the risk of dying increased with the longer FH duration. Increasing the room temperature to 25°C reduced hypothermia and the risk of pigs dying before colostrum intake.

  10. Reduction of graphene oxide at room temperature with vitamin C for RGO–TiO{sub 2} photoanodes in dye-sensitized solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Hui [Research Institute of Functional Materials, Central Iron and Steel Research Institute, No. 76 Xueyuan Nanlu, Haidian, Beijing 100081 (China); Zhang, Sam, E-mail: MSYZhang@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Chen, Ji-Tao [College of Chemistry and Molecular Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871 (China); Hu, Xiao-Ping [Research & Development Center, Advanced Technology & Materials Co., Ltd., No. 76 Xueyuan Nanlu, Haidian, Beijing 100081 (China); Du, Zhao-Fu; Qiu, Yue-Xiu; Zhao, Dong-Liang [Research Institute of Functional Materials, Central Iron and Steel Research Institute, No. 76 Xueyuan Nanlu, Haidian, Beijing 100081 (China)

    2015-06-01

    Graphene has been used to enhance conversion efficiency in dye-sensitized solar cell (DSSC) through increased electronic transportation. Introduction of graphene into DSSC is realized through reduction of graphene oxide (GO) to reduced graphene or RGO in TiO{sub 2} nanoparticles in solution. Chemical and hydrothermal reactions are two commonly used avenues. In the chemical route, toxic hydrazine and its derivatives are the typical reducing agent. Hydrothermal process is not toxic but requires prolonged heating. In this study, we mix flakes of GO with TiO{sub 2} nanoparticles and use vitamin C to realize the reduction at room temperature. The RGO–TiO{sub 2} composite films are then used as photoanode in DSSC. A conversion efficiency of 30% increase (to 7.89%) is obtained as compared to that of the pure TiO{sub 2} photoanode. - Highlights: • We produce reduced graphene (RGO)–TiO{sub 2} nanocomposite at room temperature. • The reduction is realized by vitamin C in a simple and environment-friendly way. • Reduced graphene provides a highway for electron transportation. • The RGO–P25 composite films are used as photoanode for DSSC. • Conversion efficiency of 30% increase (to 7.89%) is obtained by RGO–P25 photoanode.

  11. Implication of potassium trimolybdate nanowires as highly sensitive and selective ammonia sensor at room temperature

    Science.gov (United States)

    Joshi, Aditee C.; Gangal, S. A.

    2016-09-01

    Potassium trimolybdate nanowires are demonstrated as unique and highly selective NH3 sensing materials at room temperature. The nanowires were synthesized by using chemical route under normal ambient conditions and subsequently characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD). Gas sensors based on nanowires were fabricated by isolating and aligning nanowires between microspaced electrodes using dielectrophoresis. Room temperature gas sensing studies for different vapors indicated excellent selectivity for NH3 and capability to detect NH3 at concentrations down to ppb level. The sensors exhibited higher sensitivity for concentration range much below toxic limit of NH3 from 500 ppb up to 25 ppm. Since nanowires are isolated and aligned, the gas sensing reaction is rapid, and the availability of abundant oxide and hydroxyl surface groups on nanowires surface makes the reaction significantly prominent and selective with highly reducing nature of NH3.

  12. High-density magnetoresistive random access memory operating at ultralow voltage at room temperature.

    Science.gov (United States)

    Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

    2011-11-22

    The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch(-2), ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns.

  13. Robust room temperature ferromagnetism and band gap tuning in nonmagnetic Mg doped ZnO films

    Science.gov (United States)

    Quan, Zhiyong; Liu, Xia; Qi, Yan; Song, Zhilin; Qi, Shifei; Zhou, Guowei; Xu, Xiaohong

    2017-03-01

    Mg doped ZnO films with hexagonal wurtzite structure were deposited on c-cut sapphire Al2O3 substrates by pulsed laser deposition. Both room temperature ferromagnetism and band gap of the films simultaneously tuned by the concentration of oxygen vacancies were performed. Our results further reveal that the singly occupied oxygen vacancies should be responsible for the room temperature ferromagnetism and band gap narrowing. Singly occupied oxygen vacancies having the localized magnetic moments form bound magnetic polarons, which results in a long-range ferromagnetic ordering due to Mg doping. Moreover, band gap narrowing of the films is probably due to the formation of impurity band in the vicinity of valence band, originating from singly occupied oxygen vacancies. These results may build a bridge to understand the relationship between the magnetic and optical properties in oxide semiconductor, and are promising to integrate multiple functions in one system.

  14. Advances in methods to obtain and characterise room temperature magnetic ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Lorite, I.; Kumar, P.; Esquinazi, P. [Division of Superconductivity and Magnetism, Institute for Experimental Physics II, Fakultät für Physik und Geowissenschaften, Linnéstraße 5, 04103 Leipzig (Germany); Straube, B.; Villafuerte, M. [Laboratorio de Física del Sólido, Dpto. de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); CONICET, Dpto. de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Ohldag, H. [Stanford Synchrotron Radiation Lightsource, Stanford University, Menlo Park, California 94025 (United States); Rodríguez Torres, C. E. [IFLP-CONICET, CCT-La Plata and Departamento de Física, Universidad Nacional de La Plata (Argentina); Perez de Heluani, S. [Laboratorio de Física del Sólido, Dpto. de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán (Argentina); Antonov, V. N.; Bekenov, L. V. [Institute for Metal Physics, 36 Vernadsky Street, 03142 Kiev (Ukraine); Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany); Ernst, A. [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany); Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universitat Leipzig, Linnéstraße 2, 04103 Leipzig (Germany); and others

    2015-02-23

    We report the existence of magnetic order at room temperature in Li-doped ZnO microwires after low energy H{sup +} implantation. The microwires with diameters between 0.3 and 10 μm were prepared by a carbothermal process. We combine spectroscopy techniques to elucidate the influence of the electronic structure and local environment of Zn, O, and Li and their vacancies on the magnetic response. Ferromagnetism at room temperature is obtained only after implanting H{sup +} in Li-doped ZnO. The overall results indicate that low-energy proton implantation is an effective method to produce the necessary amount of stable Zn vacancies near the Li ions to trigger the magnetic order.

  15. Room temperature stable CO x -free H2 production from methanol with magnesium oxide nanophotocatalysts.

    Science.gov (United States)

    Liu, Zhengqing; Yin, Zongyou; Cox, Casandra; Bosman, Michel; Qian, Xiaofeng; Li, Na; Zhao, Hongyang; Du, Yaping; Li, Ju; Nocera, Daniel G

    2016-09-01

    Methanol, which contains 12.6 weight percent hydrogen, is a good hydrogen storage medium because it is a liquid at room temperature. However, by releasing the hydrogen, undesirable CO and/or CO2 byproducts are formed during catalytic fuel reforming. We show that alkaline earth metal oxides, in our case MgO nanocrystals, exhibit stable photocatalytic activity for CO/CO2-free H2 production from liquid methanol at room temperature. The performance of MgO nanocrystals toward methanol dehydrogenation increases with time and approaches ~320 μmol g(-1) hour(-1) after a 2-day photocatalytic reaction. The CO x -free H2 production is attributed to methanol photodecomposition to formaldehyde, photocatalyzed by surface electronic states of unique monodispersed, porous MgO nanocrystals, which were synthesized with a novel facile colloidal chemical strategy. An oxygen plasma treatment allows for the removal of organic surfactants, producing MgO nanocrystals that are well dispersible in methanol.

  16. Room temperature strong coupling effects from single ZnO nanowire microcavity

    KAUST Repository

    Das, Ayan

    2012-05-01

    Strong coupling effects in a dielectric microcavity with a single ZnO nanowire embedded in it have been investigated at room temperature. A large Rabi splitting of ?100 meV is obtained from the polariton dispersion and a non-linearity in the polariton emission characteristics is observed at room temperature with a low threshold of 1.63 ?J/cm2, which corresponds to a polariton density an order of magnitude smaller than that for the Mott transition. The momentum distribution of the lower polaritons shows evidence of dynamic condensation and the absence of a relaxation bottleneck. The polariton relaxation dynamics were investigated by timeresolved measurements, which showed a progressive decrease in the polariton relaxation time with increase in polariton density. © 2012 Optical Society of America.

  17. Heavy atom enhanced room-temperature phosphorimetry for ultratrace determination of harmane

    Directory of Open Access Journals (Sweden)

    Flávia F. de Carvalho Marques

    2008-01-01

    Full Text Available Harmane has been proposed for the treatment of epilepsy, AIDS and leshmaniosis. Its room-temperature phosphorescence was induced using either AgNO3 or TlNO3, enabling absolute limits of detection of 0.12 and 2.4 ng respectively, with linear dynamic ranges extending up to 456 ng (AgNO3 and 911 ng (TlNO3. Relative standard deviations around 3% were observed for substrates containing 46 ng of harmane. Such sensitivity and precision are needed because harmane intake must be strictly controlled to achieve proper therapeutic response. Interference studies were performed using thalidomide, reserpine and yohimbine. Recovery of 104±6% was achieved using solid surface room-temperature phosphorimetry. The result was comparable to the one obtained by micellar electrokinetic chromatography.

  18. Nanostructural evolution of Zn by dry roller vibration milling at room temperature

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    It remains open to date to produce stable nanostructures of single element by dry mechanical method at room temperature on a large scale. Here we report nanostructural evolution of zinc by dry roller vibration milling at room temperature, which leads to structurally near perfect zinc flakes sized 3-5 nm in diameter. The synthesized nanostructures are single crystalline, transparent, uniform, randomly oriented, almost equiaxed, and mostly free from defects. The evolution seems to open a way to optimize zinc nanostructures by the mechanical method, offer valuable references to prepare nanostructures of other metals optimally, and shed light on how to lower the size limit by mechanical milling. Single elemental metal nanostructures with excellent properties give rise to new opportunities in scientific research and development of nanotechnology.

  19. Room temperature manipulation of long lifetime spins in metallic-like carbon nanospheres

    Science.gov (United States)

    Náfrádi, Bálint; Choucair, Mohammad; Dinse, Klaus-Peter; Forró, László

    2016-07-01

    The time-window for processing electron spin information (spintronics) in solid-state quantum electronic devices is determined by the spin-lattice and spin-spin relaxation times of electrons. Minimizing the effects of spin-orbit coupling and the local magnetic contributions of neighbouring atoms on spin-lattice and spin-spin relaxation times at room temperature remain substantial challenges to practical spintronics. Here we report conduction electron spin-lattice and spin-spin relaxation times of 175 ns at 300 K in 37+/-7 nm carbon spheres, which is remarkably long for any conducting solid-state material of comparable size. Following the observation of spin polarization by electron spin resonance, we control the quantum state of the electron spin by applying short bursts of an oscillating magnetic field and observe coherent oscillations of the spin state. These results demonstrate the feasibility of operating electron spins in conducting carbon nanospheres as quantum bits at room temperature.

  20. Tunable Room Temperature Second Harmonic Generation in Glasses Doped with CuCI Nanocrystalline Quantum Dots

    Energy Technology Data Exchange (ETDEWEB)

    Thantu, Napoleon; Schley, Robert Scott; B. L. Justus

    2003-05-01

    Two-photon excited emission centered at 379-426 nm in photodarkening borosilicate glass doped with CuCl nanocrystalline quantum dots at room temperature has been observed. The emission is detected in the direction of the fundamental near-infrared beam. Time- and frequency-resolved measurements at room temperature and 77 K indicate that the emission is largely coherent light characteristic of second harmonic generation (SHG). An average conversion efficiency of ~10-10 is obtained for a 2 mm thick sample. The observed SHG can originate in the individual noncentrosymmetric nanocrystals, leading to a bulk-like contribution, and at the nanocrystal-glass interface, leading to a surface contribution. The bulk-like conversion efficiency is estimated using previously reported values of coherence length (5m) and bulk nonlinear susceptibility. This bulk-like conversion efficiency estimate is found to be smaller than the measured value, suggesting a more prominent surface contribution.

  1. Densification and strain hardening of a metallic glass under tension at room temperature.

    Science.gov (United States)

    Wang, Z T; Pan, J; Li, Y; Schuh, C A

    2013-09-27

    The deformation of metallic glasses involves two competing processes: a disordering process involving dilatation, free volume accumulation, and softening, and a relaxation process involving diffusional ordering and densification. For metallic glasses at room temperature and under uniaxial loading, disordering usually dominates, and the glass can fail catastrophically as the softening process runs away in a localized mode. Here we demonstrate conditions where the opposite, unexpected, situation occurs: the densifying process dominates, resulting in stable plastic deformation and work hardening at room temperature. We report densification and hardening during deformation in a Zr-based glass under multiaxial loading, in a notched tensile geometry. The effect is driven by stress-enhanced diffusional relaxation, and is attended by a reduction in exothermic heat and hardening signatures similar to those observed in the classical thermal relaxation of glasses. The result is significant, stable, plastic, extensional flow in metallic glasses, which suggest a possibility of designing tough glasses based on their flow properties.

  2. Development of vibration-damping resins for room-temperature application

    Science.gov (United States)

    Taniuchi, Mamoru; Takatsuka, Kohro; Fujiwara, Haruo; Korida, Kazuhiko

    1991-03-01

    Copolymers of vinyl acetate, n-butyl acrylate, VeoVa 10, and acrylic acid were prepared in order to develop new high vibration-damping resins for vibration-damping composite steel sheets for room-temperature application. The characteristics of the resins were affected by the properties of each monomer used. Vinyl acetate and n-butyl acrylate were known to have good vibration-damping properties around room temperatures. We found that VeoVa 10 had a pronounced effect on the lowering of the melt viscosity. Acrylic acid was added to improve the adhesion performance with steel sheets. The composite steel sheets produced using these resins exhibited a high loss factor of approximately 0.3 to 0.4 at 20 °C to 30 °C and 250 Hz. The melt viscosity was in the 5 to 20 Pa · s range at 180 °C.

  3. Room-temperature direct band-gap electroluminescence from germanium (111)-fin light-emitting diodes

    Science.gov (United States)

    Tani, Kazuki; Saito, Shin-ichi; Oda, Katsuya; Miura, Makoto; Wakayama, Yuki; Okumura, Tadashi; Mine, Toshiyuki; Ido, Tatemi

    2017-03-01

    Germanium (Ge) (111) fins of 320 nm in height were successfully fabricated using a combination of flattening sidewalls of a silicon (Si) fin structure by anisotropic wet etching with tetramethylammonium hydroxide, formation of thin Ge fins by selective Si oxidation in SiGe layers, and enlargement of Ge fins by Ge homogeneous epitaxial growth. The excellent electrical characteristics of Ge(111) fin light-emitting diodes, such as an ideality factor of 1.1 and low dark current density of 7.1 × 10‑5 A cm‑2 at reverse bias of ‑2 V, indicate their good crystalline quality. A tensile strain of 0.2% in the Ge fins, which originated from the mismatch of the thermal expansion coefficients between Ge and the covering SiO2 layers, was expected from the room-temperature photoluminescence spectra, and room-temperature electroluminescence corresponding to the direct band-gap transition was observed from the Ge fins.

  4. The effects of electrolysis at room temperature on retrogradation of sweet potato starch.

    Science.gov (United States)

    Xijun, Lian; Kunsheng, Zhang; Qingfeng, Luo; Xu, Zhang; Shuyi, Zhao

    2012-01-01

    The effects of electrolysis at room temperature on formation of sweet potato retrograded starch were studied by photographic method in the paper. The optimal parameters of electrolytic preparation of sweet potato retrograded starch were determined. The ratio between sweet potato starch and water was 10 g/100 mL with addition of NaCl 1.0 g/100 mL, pH value of the solution was 6.0 and the solution was electrolyzed for 30 min at 90 V at room temperature, then it was stored at 4°C for 24h after being autoclaved for 30 min at 120°C, the retrogradation rate of sweet potato starch at this condition was 33.1%, which is 138% higher than that of control group. Four possible reasons are put forward to explain the results.

  5. Room Temperature Magnetic Determination of the Current Center Line for the ITER TF Coils

    CERN Document Server

    Lerch, Philippe; Buzio, Marco; Negrazus, Marco; Baynham, Elwyn; Sanfilippo, Stephane; Foussat, Arnaud

    2014-01-01

    The ITER tokamak includes 18 superconducting D-shaped toroidal field (IT) coils. Unavoidable shape deformations as well as assembly errors will lead to field errors, which can be modeled with the knowledge of the current center line (CCL). Accurate survey during the entire manufacturing and assembly process, including transfer of survey points, is complex. In order to increase the level of confidence, a room temperature magnetic measurement of the CCL on assembled and closed winding packs is foreseen, prior to insertion into their cold case. In this contribution, we discuss the principle of the CCL determination and present a low frequency ac measurement system under development at PSI, within an ITER framework contract. The largest current allowed to flow in the TF coil at room temperature and the precision requirements for the determination of the CCL loci of the coil are hard boundaries. Eddy currents in the radial plates, the winding pack enclosures, and possibly from iron in the reinforced concrete floor...

  6. Shot-noise-limited magnetometer with sub-picotesla sensitivity at room temperature.

    Science.gov (United States)

    Lucivero, Vito Giovanni; Anielski, Pawel; Gawlik, Wojciech; Mitchell, Morgan W

    2014-11-01

    We report a photon shot-noise-limited (SNL) optical magnetometer based on amplitude modulated optical rotation using a room-temperature (85)Rb vapor in a cell with anti-relaxation coating. The instrument achieves a room-temperature sensitivity of 70 fT / √Hz at 7.6 μT. Experimental scaling of noise with optical power, in agreement with theoretical predictions, confirms the SNL behaviour from 5 μT to 75 μT. The combination of best-in-class sensitivity and SNL operation makes the system a promising candidate for application of squeezed light to a state-of-the-art atomic sensor.

  7. A highly reversible room-temperature lithium metal battery based on crosslinked hairy nanoparticles.

    KAUST Repository

    Choudhury, Snehashis

    2015-12-04

    Rough electrodeposition, uncontrolled parasitic side-reactions with electrolytes and dendrite-induced short-circuits have hindered development of advanced energy storage technologies based on metallic lithium, sodium and aluminium electrodes. Solid polymer electrolytes and nanoparticle-polymer composites have shown promise as candidates to suppress lithium dendrite growth, but the challenge of simultaneously maintaining high mechanical strength and high ionic conductivity at room temperature has so far been unmet in these materials. Here we report a facile and scalable method of fabricating tough, freestanding membranes that combine the best attributes of solid polymers, nanocomposites and gel-polymer electrolytes. Hairy nanoparticles are employed as multifunctional nodes for polymer crosslinking, which produces mechanically robust membranes that are exceptionally effective in inhibiting dendrite growth in a lithium metal battery. The membranes are also reported to enable stable cycling of lithium batteries paired with conventional intercalating cathodes. Our findings appear to provide an important step towards room-temperature dendrite-free batteries.

  8. In-situ investigation of the microstructure evolution in nanocrystalline copper electrodeposits at room temperature

    DEFF Research Database (Denmark)

    Pantleon, Karen; Somers, Marcel A. J.

    2006-01-01

    The microstructure evolution in copper electrodeposits at room temperature (self-annealing) was investigated by means of x-ray diffraction analysis and simultaneous measurements of the electrical resistivity as a function of time. In situ studies were started immediately after deposition...... growth, crystallographic texture changes by multiple twinning, and a decrease of the electrical resistivity occurred as a function of time at room temperature. The kinetics of self-annealing is strongly affected by the layer thickness: the thinner the layer, the slower the microstructure evolution is...... of the various thick layers and continued with a unique time resolution until stabilization of the recorded data occurred. Independent of the copper layer thickness, the as-deposited microstructure consisted of nanocrystalline grains with orientation dependent crystallite sizes. Orientation dependent grain...

  9. Origin of Room-Temperature Ferromagnetism for Cobalt-Doped ZnO Diluted Magnetic Semiconductor

    Institute of Scientific and Technical Information of China (English)

    PENG Long; ZHANG Huai-Wu; WEN Qi-Ye; SONG Yuan-Qiang; SU Hua; John Q. Xiao

    2008-01-01

    @@ The pure single phase of Zn0.95Co0.05O bulks is successfully prepared by solid-state reaction method. The effects of annealing atmosphere on room-temperature ferromagnetic behaviour for the Zn0.95 Co0.05O bulks are investigated. The results show that the air-annealed samples has similar weak ferromagnetic behaviour with the as-sintered samples, but the obvious ferromagnetic behaviour is observed for the samples annealed in vacuum or Ar/H2 gas, indicating that the strong ferromagnetism is associated with high oxygen vacancies density. High saturation magnetization Ms = 0.73 μB /Co and coercivity Hc = 233.8 Oe are obtained for the Ar/H2 annealed samples with pure single phase structure. The enhanced room-temperature ferromagnetic behaviour is also found in the samples with high carrier concentration controlled by doping interstitials Zn (Zni).

  10. Tannic acid assisted synthesis of flake-like hydroxyapatite nanostructures at room temperature

    Science.gov (United States)

    Vázquez, Maricela Santana; Estevez, O.; Ascencio-Aguirre, F.; Mendoza-Cruz, R.; Bazán-Díaz, L.; Zorrila, C.; Herrera-Becerra, R.

    2016-09-01

    A simple and non-expensive procedure was performed to synthesize hydroxyapatite (HAp) flake-like nanostructures, by using a co-precipitation method with tannic acid as stabilizing agent at room temperature and freeze drying. Samples were synthesized with two different salts, Ca(NO3)2 and CaCl2. X-ray diffraction analysis, Raman spectroscopy, scanning and transmission electron microscopy characterizations reveal Ca10(PO4)6(OH)2 HAp particles with hexagonal structure and P63/m space group in both cases. In addition, the particle size was smaller than 20 nm. The advantage of this method over the works reported to date lies in the ease for obtaining HAp particles with a single morphology (flakes), in high yield. This opens the possibility of expanding the view to the designing of new composite materials based on the HAp synthesized at room temperature.

  11. Unveiling the Room-Temperature Magnetoelectricity of Troilite FeS

    Science.gov (United States)

    Ricci, Fabio; Bousquet, Eric

    2016-06-01

    We report on a first-principles study of the troilite phase of iron sulfide (FeS). We show that even if, a few decades ago, this material was thought to be ferroelectric, the structural transition from the high P 63/m m c to the low P 6 ¯2 c symmetry phase does not involve polar instabilities, though the space inversion center symmetry is broken. Our calculations and symmetry analysis nevertheless reveal that FeS is magnetoelectric at room temperature with a response larger than the prototypical room-temperature magnetoelectric crystal Cr2 O3 . We also show that the spin channel decomposition of the polarization exhibits nonzero values in the opposite direction in FeS, which is actually a general hint of the presence of a magnetoelectric monopole in diagonal magnetoelectrics.

  12. Deposition of silicon oxynitride films by low energy ion beam assisted nitridation at room temperature

    Science.gov (United States)

    Youroukov, S.; Kitova, S.; Danev, G.

    2008-05-01

    The possibility is studied of growing thin silicon oxynitride films by e-gun evaporation of SiO and SiO2 together with concurrent bombardment with low energy N2+ ions from a cyclotron resonance (ECR) source at room temperature of substrates. The degree of nitridation and oxidation of the films is investigated by means of X-ray spectroscopy. The optical characteristics of the films, their environmental stability and adhesion to different substrates are examined. The results obtained show than the films deposited are transparent. It is found that in the case of SiO evaporation with concurrent N2+ ion bombardment, reactive implantation of nitrogen within the films takes place at room temperature of the substrate with the formation of a new silicon oxynitride compound even at low ion energy (150-200 eV).

  13. Synthesis and characterization of CePO4 nanowires via microemulsion method at room temperature

    Institute of Scientific and Technical Information of China (English)

    Yi Bin Yin; Xin Shao; Li Min Zhao; Wen Zhi Li

    2009-01-01

    Uniform CePO4 nanowires with diameter of about 25 nm were synthesized by the water-in-oil microemulsion method at room temperature from cerous chloride, sodium orthophosphate, sodium chloride, cyclohexane, Triton X-100 and cetyltrimethyl ammonium bromide (CTAB). The crystal structure and morphology of the nanowires were characterized by XRD and TEM, respectively. The U'V-vis absorption was detected by UV-vis spectrophotometer techniques. The results showed that as-prepared nanowires with the hexagonal phase have obvious quantum confinement effect and semiconductor characteristics. Little sodium chloride could play a positive role on the formation of CePO4 nanowires at room temperature. The size of the nanowires can be controlled through the joining of sodium chloride.

  14. Room-temperature ferromagnetic properties of Cu-doped ZnO rod arrays

    Indian Academy of Sciences (India)

    C H Xia; C G Hu; C H Hu; Z Ping; F Wang

    2011-08-01

    We have investigated properties of the Cu-doped ZnO crystalline film synthesized by the hydrothermal method. X-ray diffraction and X-ray photoelectron spectroscopy results provide the evidence that Cu2+ is incorporated into the ZnO lattices. Photoluminescence spectrum of the rod arrays shows that the UV emission peak shifts a little to lower energy and its intensity decreased. There are another two emission peaks centred in blue and green regions because of the incorporation of Cu2+ ions. The rod arrays have exhibited room-temperature ferromagnetic behaviour with the remanence of 0.926 × 10-3 emu/cm3. We suggest that the exchange interaction between local spin-polarized electrons (such as the electrons of Cu2+ ions) and conductive electrons is the cause of room-temperature ferromagnetism.

  15. Nano/Micro HKUST-1 Fabricated by Coordination Modulation Method at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    NA Li-yan; HUA Rui-nian; NING Gui-ling; OU Xiao-xia

    2012-01-01

    A simple and fast route for the synthesis of metal-organic framework(MOF) particles was presented.Cu3(BTC)2(HKUST-1,BTC=1,3,5-benzenetricarboxylate),one of the most well-known MOFs,was synthesized at room temperature via coordination modulation method.By adding different modulators(monocarboxylic acids) into the reaction system,the morphologies of HKUST-1 crystals were tuned from nano spheres to micro octahedrons at room temperature without any complex equipment.X-Ray diffractions and gas sorption measurements revealed highly crystalline particles with large Brunauer-Emmett-Teller(BET) surface areas(1116-1273 m2/g) and total pore volumes(0.62-0.73 cm3/g).The significantly small particle sizes and high capacity of gas sorption are considered advantageous for envisaged application in practical industrial process.

  16. Cavity-enhanced room-temperature high sensitivity optical Faraday magnetometry

    Science.gov (United States)

    Sun, Hui; Lei, Yaohua; Fan, Shuangli; Zhang, Qiaolin; Guo, Hong

    2017-01-01

    We propose a cavity QED system with two-photon Doppler-free configuration for weak magnetic field detection with high sensitivity at room temperature based on cavity electromagnetically induced transparency. Owing to the destructive interference induced by the control and driving fields, two transparency channels are opened. The Faraday rotation within two transparency channels can be used to detect weak magnetic field with high sensitivity at room temperature. The sensitivity with single photon and multiphoton probe inputs is analyzed. With single photon measurement, our numerical calculations demonstrate that the sensitivity with 3.8nT/√{Hz} and 6.4nT/√{Hz} could be achieved. When we measure the magnetic field with multiphoton input, the sensitivity can be improved to 7.7fT/√{Hz} and 25.6fT/√{Hz} under the realistic experimental conditions.

  17. Observation of Multi-Electromagnetically Induced Transparency in V-type Rubidium at Room Temperature

    CERN Document Server

    Ying, Kang; Qi, Yihong; Chen, Dijun; Cai, Haiwen; Qu, Ronghui; Gong, Shangqing

    2013-01-01

    A detailed experimental investigation and theoretical analysis have been made in the V-type 85Rb atomic medium at room temperature. Seven electromagnetically induced transparency windows, including a central double-peak-structure, have been observed experimentally when a coupling field and a probe field are applied into the ground and first excited states. By taking into account the hyperfine splitting of the excited state, our theoretical analysis gives good explanation for the observed phenomena.

  18. On the thermodynamic path enabling a room-temperature, laser-assisted graphite to nanodiamond transformation

    OpenAIRE

    Gorrini, F.; M. Cazzanelli; Bazzanella, N.; Edla, R.; Gemmi, M.; Cappello, V; David, J.; Dorigoni, C.; Bifone, A.; Miotello, A.

    2016-01-01

    Nanodiamonds are the subject of active research for their potential applications in nano-magnetometry, quantum optics, bioimaging and water cleaning processes. Here, we present a novel thermodynamic model that describes a graphite-liquid-diamond route for the synthesis of nanodiamonds. Its robustness is proved via the production of nanodiamonds powders at room-temperature and standard atmospheric pressure by pulsed laser ablation of pyrolytic graphite in water. The aqueous environment provide...

  19. Two-Dimensional Metrology with Flatbed Scanners at Room and Liquid Nitrogen Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Grau Carles, A.; Grau Malonda, A. [CIEMAT. Madrid (Spain)

    2000-07-01

    We study the capability of the commercial flatbed scanner as a measuring instrument of two-coordinate sample both at room and liquid nitrogen temperatures. We describes simple procedure to calibrate the scanner, and the most adequate standard configuration to carry out the measurements. To illustrate the procedure, we measure the relative positions of the conductors in a cross-section of a superconducting magnet of CERN. (Author) 8 refs.

  20. Photochemical removal of organic contaminants from silicon surface at room temperature

    Science.gov (United States)

    Fominski, V. Yu.; Naoumenko, O. I.; Nevolin, V. N.; Alekhin, A. P.; Markeev, A. M.; Vyukov, L. A.

    1996-04-01

    Using in situ x-ray photoelectron spectroscopy we have investigated the possibility of photochemical organic contaminant removal from a silicon surface at room temperature in oxygen and fluorine containing atmospheres (O2, NF3/H2, O2/NF3/H2). In contrast to UV irradiation in O2 and NF3/H2 reagents, the possibility of complete organic contaminant removal has been observed in O2/NF3/H2 gas mixture.

  1. TaS2 nanosheet-based room-temperature dosage meter for nitric oxide

    Directory of Open Access Journals (Sweden)

    Qiyuan He

    2014-09-01

    Full Text Available A miniature dosage meter for toxic gas is developed based on TaS2 nanosheets, which is capable of indicating the toxic dosage of trace level NO at room temperature. The TaS2 film-based chemiresistor shows an irreversible current response against the exposure of NO. The unique non-recovery characteristic makes the TaS2 film-based device an ideal indicator of total dosage of chronicle exposure.

  2. Synthesis of Crystalline Nanosized Titanium Dioxide via a Reverse Micelle Method at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Crystalline TiO2 nanoparticles were synthesized by hydrolysis of titanium tetrabutoxidein the presence of hydrochloric aeid in NP-5 (lgepal CO-520)/ cyclohcxane reverse micellesolution at room temperature. Pure rutilc nanoparticles were obtained at an appropriate acidconcentration. The influcnces of various reaction conditions such as the concentration of acids,water content value (w=[H2O]/[NP-5]) on the formation, crystal phase, morphology, and size of theTiO2 particles were investigated.

  3. Nonlinear behavior of three-terminal graphene junctions at room temperature

    Science.gov (United States)

    Kim, Wonjae; Pasanen, Pirjo; Riikonen, Juha; Lipsanen, Harri

    2012-03-01

    We demonstrate nonlinear behavior in three-terminal T-branch graphene devices at room temperature. A rectified nonlinear output at the center branch is observed when the device is biased by a push-pull configuration. Nonlinearity is assumed to arise from a difference in charge transfer through the metal-graphene contact barrier between two contacts. The sign of the rectification can be altered by changing the carrier type using the back-gate voltage.

  4. Materials for spintronic: Room temperature ferromagnetism in Zn-Mn-O interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Quesada, A. [Instituto de Magnetismo Aplicado and Departamento de Fisica de Materiales Universidad Complutense, P.O. Box 155, Las Rozas, Madrid (Spain); Garcia, M.A. [Instituto de Magnetismo Aplicado and Departamento de Fisica de Materiales Universidad Complutense. P.O. Box 155, Las Rozas, Madrid (Spain); Crespo, P. [Instituto de Magnetismo Aplicado and Departamento de Fisica de Materiales Universidad Complutense, P.O. Box 155, Las Rozas, Madrid (Spain); Hernando, A. [Instituto de Magnetismo Aplicado and Departamento de Fisica de Materiales Universidad Complutense, P.O. Box 155, Las Rozas, Madrid (Spain)]. E-mail: ahernando@renfe.es

    2006-09-15

    In this paper we study the room temperature ferromagnetism reported on Mn-doped ZnO and ascribed to spin polarization of conduction electrons. We experimentally show that the ferromagnetic behaviour is associated to the coexistence of Mn{sup 3+} and Mn{sup +4} in MnO{sub 2} grains where diffusion of Zn promotes the Mn{sup 4+{yields}}Mn{sup 3+} reduction. Potential uses of this material in spintronic devices are analysed.

  5. Continuous-wave operation of a room-temperature Tm: YAP-pumped Ho: YAG laser

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We report a continuous-wave (CW) 2.1-μm Ho:YAG laser operating at room temperature pumped by a diode-pumped 1.94-?m Tm:YAP laser.The maximum output power of 1.5 W is obtained from Ho:YAG laser,corresponding to Tm-to-Ho slope efficiency of 17.9% and diode-to-He conversion efficiency of 5.6%.

  6. Comment on "Supercurrent in a room temperature Bose-Einstein magnon condensate"

    OpenAIRE

    2016-01-01

    The comment explains that the preprint arXiv:1503.0042 has not presented persuasive theoretical or experimental arguments of existence of spin supercurrents in a magnon condensate prepared in a room temperature yttrium-iron-garnet magnetic film because the authors did not check known criteria for existence of spin supercurrents in magnetically ordered materials. Also they did not compare their supercurrent interpretation with a competing and more realistic scenario of transport by spin diffus...

  7. Efficient alpha-Methylenation of Carbonyl Compounds in Ionic Liquids at Room Temperature

    OpenAIRE

    Vale, JA; Zanchetta, DF; Moran, PJS; RODRIGUES, JAR

    2009-01-01

    The application of several 1-butyl-3-methylimidazolium (BMIM) salt ionic liquids as solvent in the alpha-methylenation of carbonyl compounds at room temperature is reported. The ionic liquid [BMIM][NTf(2)] gave a clean reaction in a short time and good yields of several alpha-methylene carbonyl compounds. This ionic liquid was reused without affecting the reaction rates or yields over seven runs.

  8. Research on CdZnTe and Other Novel Room Temperature Gamma Ray Spectrometer Materials

    Energy Technology Data Exchange (ETDEWEB)

    Arnold Burger; Michael gGoza; Yunlong Cui; Utpal N. Roy; M. Guo

    2007-05-05

    Room temperature gamma-ray spectrometers are being developed for a number of years for national security applications where high sensitivity, low operating power and compactness are indispensable. The technology has matured now to the point where large volume (several cubic centimeters) and high energy resolution (approximately 1% at 660 eV) of gamma photons, are becoming available for their incorporation into portable systems for remote sensing of signatures from nuclear materials.

  9. Demonstration of coherent emission from high-$\\beta$ photonic crystal nanolasers at room temperature

    CERN Document Server

    Hostein, Richard; Gratiet, Luc Le; Talneau, Anne; Beaudoin, Gregoire; Robert-Philip, Isabelle; Sagnes, Isabelle; Beveratos, Alexios

    2010-01-01

    We report on lasing at room temperature and at telecommunications wavelength from photonic crystal nanocavities based on InAsP/InP quantum dots. Such laser cavities with a small modal volume and high quality factor display a high spontaneous emission coupling factor beta. Lasing is confirmed by measuring the second order autocorrelation function. A smooth transition from chaotic to coherent emission is observed, and coherent emission is obtained at 8 times the threshold power.

  10. Demonstration of coherent emission from high-beta photonic crystal nanolasers at room temperature.

    Science.gov (United States)

    Hostein, R; Braive, R; Le Gratiet, L; Talneau, A; Beaudoin, G; Robert-Philip, I; Sagnes, I; Beveratos, A

    2010-04-15

    We report on lasing at room temperature and at telecommunications wavelength from photonic crystal nanocavities based on InAsP/InP quantum dots. Such laser cavities with a small modal volume and high quality factor display a high spontaneous emission coupling factor (beta). Lasing is confirmed by measuring the second-order autocorrelation function. A smooth transition from chaotic to coherent emission is observed, and coherent emission is obtained at eight times the threshold power.

  11. Room Temperature Synthesis and Catalytic Properties of Surfactant-Modified Ag Nanoparticles

    OpenAIRE

    Weihua Li; Congtao Sun; Baorong Hou; Xiaodong Zhou

    2012-01-01

    Well-dispersed Ag nanoparticles with size of 20–30 nm were synthesized in water at room temperature with a self-made novel imidazoline Gemini surfactant quaternary ammonium salt of di (2-heptadecyl-1-formyl aminoethyl imidazoline) hexanediamine. Transmission electron microscopy, X-ray powder diffraction, ultraviolet-visible absorption spectra, and Fourier transform infrared ray were used to characterize the Ag nanoparticles. Results showed that the micellized aggregation of imidazoline Gemini...

  12. Room Temperature Direct Band Gap Emission from Ge p-i-n Heterojunction Photodiodes

    OpenAIRE

    2012-01-01

    Room temperature direct band gap emission is observed for Si-substrate-based Ge p-i-n heterojunction photodiode structures operated under forward bias. Comparisons of electroluminescence with photoluminescence spectra allow separating emission from intrinsic Ge (0.8 eV) and highly doped Ge (0.73 eV). Electroluminescence stems from carrier injection into the intrinsic layer, whereas photoluminescence originates from the highly n-doped top layer because the exciting visible laser wavelength is ...

  13. Synthesis of silicon carbide at room temperature from colloidal suspensions of silicon dioxide and carbon nanotubes

    Science.gov (United States)

    Zhukalin, D. A.; Tuchin, A. V.; Kulikova, T. V.; Bityutskaya, L. A.

    2015-11-01

    Experimental and theoretical approaches were used for the investigation of mechanisms and conditions of self-organized nanostructures formation in the drying drop of the mixture of colloidal suspensions of nanoscale amorphous silicon dioxide and carbon nanotubes. The formation of rodlike structures with diameter 250-300nm and length ∼4pm was revealed. The diffraction analysis of the obtained nanostructures showed the formation of the silicon carbide phase at room temperature.

  14. In vitro mechanical properties comparsion of four room temperature curing denture base resin:

    Institute of Scientific and Technical Information of China (English)

    LI Zhian; XIA Xuetong; Xiao Qun

    2001-01-01

    @@ The room temperature curing denture base resin has low mechanical properties,so it was limited in clinical application. It had previously disscused that reinfored maehinical properties with metal fiber, glass fiber,plastic fiber and by adding the fracture resistance substances in powderThe aim of this study was to determined the mechanical properities of four roomtemperature curing denture base resin which had been modified performance withhigh boil point methacrylate.

  15. Novel Nano-scale Overlay Alignment Method for Room-temperature Imprint Lithography

    Institute of Scientific and Technical Information of China (English)

    WANG Li; DING Yu-cheng; LU Bing-heng; LI Han-song; YAN Le; QIU Zhi-hui; LIU Hong-zhong; YIN Lie

    2005-01-01

    A novel nano-scale alignment technique based on Moiré signal for room-temperature imprint are used to estimate the alignment errors in x and y directions. The experiment result indicates that complex and the alignment resolutions obtained in x and y directions are ±20 nm(3σ) and ±24 nm(3σ). They can meet the requirement of alignment accuracy for submicron imprint lithography.

  16. Microscopic Superconductivity and Room Temperature Electronics of High-Tc Cuprates

    Institute of Scientific and Technical Information of China (English)

    LIU Fu-Sui; CHEN Wan-Fang

    2008-01-01

    This paper points out that the Landau criterion for macroscopic superfluidity of He H is only a criterion for microscopic superfluidity of 4He, extends the Landau criterion to microscopic superconductivity in fermions (electron and hole) system and system with Cooper pairs without long-range phase coherence. This paper gives another three non-superconductive systems that are of microscopic superconductivity. This paper demonstrates that one application of microscopic superconductivity is to establish room temperature electronics of the high-To cuprates.

  17. Anion pairs in room temperature ionic liquids predicted by molecular dynamics simulation, verified by spectroscopic characterization

    Energy Technology Data Exchange (ETDEWEB)

    Schwenzer, Birgit; Kerisit, Sebastien N.; Vijayakumar, M.

    2014-01-01

    Molecular-level spectroscopic analyses of an aprotic and a protic room-temperature ionic liquid, BMIM OTf and BMIM HSO4, respectively, have been carried out with the aim of verifying molecular dynamics simulations that predict anion pair formation in these fluid structures. Fourier-transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy of various nuclei support the theoretically-determined average molecular arrangements.

  18. Ruthenium(III Chloride Catalyzed Acylation of Alcohols, Phenols, and Thiols in Room Temperature Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Mingzhong Cai

    2009-09-01

    Full Text Available Ruthenium(III chloride-catalyzed acylation of a variety of alcohols, phenols, and thiols was achieved in high yields under mild conditions (room temperature in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]. The ionic liquid and ruthenium catalyst can be recycled at least 10 times. Our system not only solves the basic problem of ruthenium catalyst reuse, but also avoids the use of volatile acetonitrile as solvent.

  19. Trends in the design of front-end systems for room temperature solid state detectors

    OpenAIRE

    Manfredi, Pier F.; Re, Valerio

    2003-01-01

    The paper discusses the present trends in the design of low-noise front-end systems for room temperature semiconductor detectors. The technological advancement provided by submicron CMOS and BiCMOS processes is examined from several points of view. The noise performances are a fundamental issue in most detector applications and suitable attention is devoted to them for the purpose of judging whether or not the present processes supersede the solutions featuring a field-effect transistor...

  20. Synthesis of multi-hydroxyl and sulfonyl dual-functionalized room temperature ionic liquids

    Institute of Scientific and Technical Information of China (English)

    Guo Yang Zhu; Rong Wang; Guo Hua Liu; Li Qun Xu; Bei Zhang; Xia Qin Wu

    2007-01-01

    Starting from the hydroxylamine (dimethyl amino ethanol, triethanolamine) and 1,3-propane sultone, a series of hydroxyl and sulfonyl dual-functionalized zwitterionic salts and corresponding acidic room temperature ionic liquids have been synthesized.The hydroxyl groups of the synthesized substances were confirmed by the 1H NMR measurement.These zwitterionic salts and ionic liquids may be used for synthesizing other functionalized ionic liquids or ionic liquid-polymer (polyelectrolyte).

  1. Mechanochemical synthesis of maghemite/silica nanocomposites: advanced materials for aqueous room-temperature catalysis.

    Science.gov (United States)

    Ojeda, Manuel; Pineda, Antonio; Romero, Antonio A; Barrón, Vidal; Luque, Rafael

    2014-07-01

    A simple, environmentally friendly, and highly reproducible protocol has been developed for the mechanochemical preparation of advanced nanocatalytic materials in a one-pot process. The materials proved to have unprecedented activities in aqueous Suzuki couplings at room temperature, paving the way for a new generation of highly active and stable advanced nanocatalysts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Mixing of 10-microm radiation in room-temperature Schottky diodes.

    Science.gov (United States)

    Tannenwald, P E; Fetterman, H R; Freed, C; Parker, C D; Clifton, B J; O'Donnell, R G

    1981-10-01

    Schottky diodes have been used as room-temperature mixers of CO(2)-laser radiation. When a microwave local oscillator signal was introduced directly into the diode, beat notes between lasers separated by up to 69 GHz were observed. At CO(2) frequencies (30 THz) the photon energy exceeds the measured dc nonlinearities, and the device is expected to approach operation as a photon counter rather than a classical resistive mixer.

  3. Optical readout of coupling between a nanomembrane and an LC circuit at room temperature

    DEFF Research Database (Denmark)

    Bagci, T.; Simonsen, A.; Zeuthen, E.

    2013-01-01

    via a mechanical interface is of potential interest, as it would allow for low noise optical detection and laser cooling of weak electrical excitations. In a recent paper [4], a scheme was proposed for room temperature applications where a membrane converts rf electrical excitations in an LC circuit...... is within reach. Furthermore the electromechanical part can be placed in an optical cavity for simultaneous readout and laser cooling of electrical excitations in an LC circuit....

  4. Electrochemical properties of room temperature ionic liquids incorporating BF4- and TFSI- anions as green electrolytes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhengxi; GAO Xuhui; YANG Li

    2005-01-01

    Two series of room temperature ionic liquids, 1-alkyl-3-methylimidazolium tetrafluoroborate and 1-alkyl- 3-methylimidazolium bis(trifluoromethylsulfonyl)imide (n = 2―4) as electrolytes were prepared and fundamental electrochemical properties of the neat ionic liquids and those mixed with an organic solvent (EC-DMC-DEC, 1:1:1, mass ratio) were investigated. It was found that the Arrhenius equation is approximately fit for the relationship between conductivity and temperature for neat ionic liquids within lower temperature range (298―323 K). The VTF interpretation describes the conductivity temperature dependence for the ionic liquids containing tetrafluoroborate anion more accurately than those containing bis(trifluoromethylsulfon- yl)imide anion within wider temperature range. The potential windows are approximately 4.0 V for all these ionic liquids. Conductivities of the mixed electrolytes show a maximum value as the solution concentrations increase.

  5. Decoupling charge transport from the structural dynamics in room temperature ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Phillip [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Agapov, Alexander L [ORNL; Kisliuk, Alexander [ORNL; Sun, Xiao-Guang [ORNL; Dai, Sheng [ORNL; Novikov, Vladimir [ORNL; Sokolov, Alexei P [ORNL

    2011-01-01

    Light scattering and dielectric spectroscopy measurements were performed on the room temperature ionic liquid (RTIL) [C4mim][NTf2] in a broad temperature and frequency range. Ionic conductivity was used to estimate self-diffusion of ions, while light scattering was used to study structural relaxation. We demonstrate that the ionic diffusion decouples from the structural relaxation process as the temperature of the sample decreases toward Tg. The strength of the decoupling appears to be significantly lower than that expected for a supercooled liquid of similar fragility. The structural relaxation process in the RTIL follows well the high-temperature mode coupling theory (MCT) scenario. Using the MCT analysis we estimated the dynamic crossover temperature in [C4mim][NTf2] to be Tc 225 5 K. However, our analysis reveals no sign of the dynamic crossover in the ionic diffusion process.

  6. Room to high temperature measurements of flexible SOI FinFETs with sub-20-nm fins

    KAUST Repository

    Diab, Amer El Hajj

    2014-12-01

    We report the temperature dependence of the core electrical parameters and transport characteristics of a flexible version of fin field-effect transistor (FinFET) on silicon-on-insulator (SOI) with sub-20-nm wide fins and high-k/metal gate-stacks. For the first time, we characterize them from room to high temperature (150 °C) to show the impact of temperature variation on drain current, gate leakage current, and transconductance. Variation of extracted parameters, such as low-field mobility, subthreshold swing, threshold voltage, and ON-OFF current characteristics, is reported too. Direct comparison is made to a rigid version of the SOI FinFETs. The mobility degradation with temperature is mainly caused by phonon scattering mechanism. The overall excellent devices performance at high temperature after release is outlined proving the suitability of truly high-performance flexible inorganic electronics with such advanced architecture.

  7. Modelling the impact of room temperature on concentrations of polychlorinated biphenyls (PCBs) in indoor air

    DEFF Research Database (Denmark)

    Lyng, Nadja; Clausen, Per Axel; Lundsgaard, Claus;

    2016-01-01

    Buildings contaminated with polychlorinated biphenyls (PCBs) are a health concern for the building occupants. Inhalation exposure is linked to indoor air concentrations of PCBs, which are known to be affected by indoor temperatures. In this study, a highly PCB contaminated room was heated to six...... temperature levels between 20 and 30 C, i.e. within the normal fluctuation of indoor temperatures, while the air exchange rate was constant. The steady-state air concentrations of seven PCBs were determined at each temperature level. A model based on Clausius–Clapeyron equation, ln(P) = −H/RT + a0, where...... changes in steady-state air concentrations in relation to temperature, was tested. The model was valid for PCB-28, PCB-52 and PCB-101; the four other congeners were sporadic or non-detected. For each congener, the model described a large proportion (R2>94%) of the variation in indoor air PCB levels...

  8. Room temperature ferromagnetism of tin oxide nanocrystal based on synthesis methods

    Energy Technology Data Exchange (ETDEWEB)

    Sakthiraj, K.; Hema, M. [Department of Physics, Kamaraj College of Engineering and Technology, Virudhunagar 626001, Tamil Nadu (India); Balachandrakumar, K. [Department of Physics, Raja Doraisingam Government Arts College, Sivagangai 630561, Tamil Nadu (India)

    2016-04-15

    The experimental conditions used in the preparation of nanocrystalline oxide materials play an important role in the room temperature ferromagnetism of the product. In the present work, a comparison was made between sol–gel, microwave assisted sol–gel and hydrothermal methods for preparing tin oxide nanocrystal. X-ray diffraction analysis indicates the formation of tetragonal rutile phase structure for all the samples. The crystallite size was estimated from the HRTEM images and it is around 6–12 nm. Using optical absorbance measurement, the band gap energy value of the samples has been calculated. It reveals the existence of quantum confinement effect in all the prepared samples. Photoluminescence (PL) spectra confirms that the luminescence process originates from the structural defects such as oxygen vacancies present in the samples. Room temperature hysteresis loop was clearly observed in M–H curve of all the samples. But the sol–gel derived sample shows the higher values of saturation magnetization (M{sub s}) and remanence (M{sub r}) than other two samples. This study reveals that the sol–gel method is superior to the other two methods for producing room temperature ferromagnetism in tin oxide nanocrystal.

  9. Hydrogenation of nanocrystalline Mg at room temperature in the presence of TiH(2).

    Science.gov (United States)

    Lu, Jun; Choi, Young Joon; Fang, Zhigang Zak; Sohn, Hong Yong; Rönnebro, Ewa

    2010-05-19

    Magnesium and magnesium-based alloys are considered attractive candidates as rechargeable hydrogen storage materials because of their high hydrogen storage capacities (theoretically up to 7.6 wt %), reversibility, and low cost. In this work, the hydrogenation of nanocrystalline magnesium at room temperature in the presence of TiH(2) was studied. The magnesium was derived by dehydrogenation of nanostructured MgH(2)-0.1TiH(2) prepared by using an ultra-high-energy and high-pressure planetary milling technique. Significant uptake of hydrogen by magnesium at room temperature was observed. The results demonstrate that the nanostructured MgH(2)-0.1TiH(2) system is superior to undoped nano- or micrometer-scaled MgH(2) with respect to the hydrogenation properties of magnesium at room temperature. This finding is potentially useful for a range of energy applications including mobile or stationary hydrogen fuel cells, cooling medium in electricity generation, and differential pressure compressors.

  10. Ultrafast Room-Temperature Single Photon Emission from Quantum Dots Coupled to Plasmonic Nanocavities.

    Science.gov (United States)

    Hoang, Thang B; Akselrod, Gleb M; Mikkelsen, Maiken H

    2016-01-13

    Efficient and bright single photon sources at room temperature are critical components for quantum information systems such as quantum key distribution, quantum state teleportation, and quantum computation. However, the intrinsic radiative lifetime of quantum emitters is typically ∼10 ns, which severely limits the maximum single photon emission rate and thus entanglement rates. Here, we demonstrate the regime of ultrafast spontaneous emission (∼10 ps) from a single quantum emitter coupled to a plasmonic nanocavity at room temperature. The nanocavity integrated with a single colloidal semiconductor quantum dot produces a 540-fold decrease in the emission lifetime and a simultaneous 1900-fold increase in the total emission intensity. At the same time, the nanocavity acts as a highly efficient optical antenna directing the emission into a single lobe normal to the surface. This plasmonic platform is a versatile geometry into which a variety of other quantum emitters, such as crystal color centers, can be integrated for directional, room-temperature single photon emission rates exceeding 80 GHz.

  11. Highly active mesoporous ferrihydrite supported pt catalyst for formaldehyde removal at room temperature.

    Science.gov (United States)

    Yan, Zhaoxiong; Xu, Zhihua; Yu, Jiaguo; Jaroniec, Mietek

    2015-06-01

    Ferrihydrite (Fh) supported Pt (Pt/Fh) catalyst was first prepared by combining microemulsion and NaBH4 reduction methods and investigated for room-temperature removal of formaldehyde (HCHO). It was found that the order of addition of Pt precursor and ferrihydrite in the preparation process has an important effect on the microstructure and performance of the catalyst. Pt/Fh was shown to be an efficient catalyst for complete oxidation of HCHO at room temperature, featuring higher activity than magnetite supported Pt (Pt/Fe3O4). Pt/Fh and Pt/Fe3O4 exhibited much higher catalytic activity than Pt supported over calcined Fh and TiO2. The abundance of surface hydroxyls, high Pt dispersion and excellent adsorption performance of Fh are responsible for superior catalytic activity and stability of the Pt/Fh catalyst. This work provides some indications into the design and fabrication of the cost-effective and environmentally benign catalysts with excellent adsorption and catalytic oxidation performances for HCHO removal at room temperature.

  12. Giant magnetocaloric effect near room temperature in the off-stoichiometric Mn-Co-Ge alloy

    Science.gov (United States)

    Sharma, V. K.; Manekar, M. A.; Srivastava, Himanshu; Roy, S. B.

    2016-12-01

    We report a giant magnetocaloric effect near room temperature in an off-stoichiometric Mn-Co-Ge alloy, across the magnetostructural transition. The isothermal entropy change accompanying this transition has a peak value of nearly 40 J kg-1 K-1 near 297 K for a field excursion of 70 kOe, and a refrigerant capacity of 270 J kg-1 with the hot end at 302.5 K and cold end at 293.5 K. We also present an experimental protocol to avoid spurious peaks in the magnetocaloric effect across a sharp first order magnetostructural transition, not confined to Mn-Co-Ge alone, where metastability during the transition could influence the measured magnetization and thus the estimated entropy change. The estimated entropy change in the present off-stoichiometric Mn-Co-Ge alloy is possibly the highest reported value near room temperature in undoped Mn-Co-Ge alloys and underlines the potential of the alloy for technological applications in room temperature magnetic refrigeration.

  13. Room temperature aging to guarantee microbiological safety of Brazilian artisan Canastra cheese

    Directory of Open Access Journals (Sweden)

    Milene Therezinha das Dores

    2013-03-01

    Full Text Available Canastra cheese is one of the oldest and most traditional cheeses made from raw milk in Brazil. However, this type of practice may have severe consequences for human health. According to the current legislation, any cheese made from raw milk must be aged for at least 60 days. Traditionally, Canastra cheese is consumed after different ripening periods, but consumers usually prefer those that are aged less than eight days. This study aimed to evaluate the effects of physicochemical and microbiological parameters, with emphasis on the pathogenic microbiota regulated by law, on cheese aged at room temperature and under refrigeration. Cheese samples were collected from eight different cheese producers located in the Serra da Canastra region twice a year (rainy and dry seasons and analyzed with 8, 15, 22, 29, 36, and 64 days of ripening. Room temperature aging effectively reduced pathogens, reaching the total count established by law in 22 days, regardless of the season. However, ripening under refrigeration, it was ineffective in reducing the Staphylococcus aureus counts to the legislation limits, even after 64 days. Therefore, Canastra cheese should be ripened for at least 22 days at room temperature in order to fulfill the safety regulatory limits.

  14. TEM and SANS investigation of age hardened Nimonic PE16 after cyclic loading at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sundararaman, M.; Chen, W.; Wahi, R.P.; Wiedenmann, A.; Wagner, W.; Petry, W. (Bhabha Atomic Research Centre, Bombay (India) Berlin, Technische Universitaet, (Germany) Hahn-Meitner-Institut Berlin GmbH, (Germany) Paul Scherrer Institut, Villigen (Switzerland) Institut Max von Laue - Paul Langevin, Grenoble (France))

    1992-05-01

    A nickel-base superalloy Nimonic PE16 shows softening when subjected to low cycle fatigue (LCF) at room temperature. In this work, small-angle neutron scattering (SANS) and transmission electron microscopy (TEM) were used to study the morphology of gamma-prime precipitates in the Nimonic PE16 after LCF at room temperature. In TEM dark-field images using superlattice reflections, deformation bands free of gamma-prime precipitates in the Nimonic PE16 after LCF at room temperature. In TEM dark-field images using superlattice reflections, deformation bands free of gamma-prime precipitates are observed. SANS measurements allowed the characterization of the disappeared precipitates with regard to their average size, size distribution and volume fraction by comparing the scattered intensities of loaded and unloaded specimens. An analysis of the results shows that the gamma-prime precipitates within the deformation bands have completely dissolved and not just disordered or cut to sizes smaller than the TEM resolution limit. 14 refs.

  15. Performance improvement of ZnO film by room-temperature oxygen plasma pretreatment

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ping; XIA Yi-ben; WANG Lin-jun; LIU Jian-min; XU Run; PENG Hong-yan; SHI Wei-min

    2006-01-01

    The room-temperature oxygen plasma treatment before depositing ZnO films on nanocrystalline diamond substrates was studied. The nanocrystalline diamond substrates were pretreated in oxygen plasma at 50 W for 30 min at room temperature and then ZnO films were sputtered on diamond substrates at 400 W. The X-ray diffraction (XRD) patterns show that the c-axis orientation of ZnO film increases evidently after oxygen plasma pretreatment. The AFM and SEM measurements also show that the high c-axis orientation of ZnO film and the average surface roughness is less than 5 nm. The resistivity of ZnO films increases nearly two orders of magnitude to 1.04×108 Ω·cm. As a result,room-temperature oxygen plasma pretreatment is indeed a simple and effective way to improve the performance of ZnO film used in SAW devices by ameliorating the combination between diamond film and ZnO film and also complementing the absence of oxygen atoms in ZnO film.

  16. Influence of non-resonant effects on the dynamics of quantum logic gates at room temperature

    Science.gov (United States)

    Berman, G. P.; Bishop, A. R.; Doolen, G. D.; López, G. V.; Tsifrinovich, V. I.

    2001-01-01

    We study numerically the influence of non-resonant effects on the dynamics of a single- π-pulse quantum CONTROL-NOT (CN) gate in a macroscopic ensemble of four-spin molecules at room temperature. The four nuclear spins in each molecule represent a four-qubit register. The qubits are “labeled” by the characteristic frequencies, ωk, ( k=0-3) due to the Zeeman interaction of the nuclear spins with the magnetic field. The qubits interact with each other through an Ising interaction of strength J. The paper examines the feasibility of implementing a single-pulse quantum CN gate in an ensemble of quantum molecules at room temperature. We determine a parameter region, ωk and J, in which a single-pulse quantum CN gate can be implemented at room temperature. We also show that there exist characteristic critical values of parameters, Δ ωcr≡| ωk‧ - ωk| cr and Jcr, such that for JJcr and Δ ωk≡| ωk‧ - ωk|<Δ ωcr, non-resonant effects are sufficient to destroy the dynamics required for quantum logic operations.

  17. Evidence for room temperature delignification of wood using hydrogen peroxide and manganese acetate as a catalyst.

    Science.gov (United States)

    Lucas, Marcel; Hanson, Susan K; Wagner, Gregory L; Kimball, David B; Rector, Kirk D

    2012-09-01

    Manganese acetate was found to catalyze the oxidative delignification of wood with hydrogen peroxide at room temperature. The delignification reaction was monitored by optical and Raman microscopy, and liquid chromatography/mass spectrometry. When exposed to H(2)O(2) and Mn(OAc)(3) in aqueous solution, poplar wood sections were converted into a fine powder-like material which consisted of individual wood cells within 4 days at room temperature and without agitation. Optical and Raman microscopy provided the spatial distribution of cellulose and lignin in the wood structure, and showed the preferential oxidation of lignin-rich middle lamellae. Raman spectra from the solid residue revealed a delignified and cellulose-rich material. Glucose yields following enzymatic hydrolysis were 20-40% higher in poplar sawdust pretreated with Mn(OAc)(3) for 2, 4, and 7 days at room temperature than those in sawdust exposed to water only for identical durations, suggesting the viability of this mild, inexpensive method for pretreatment of lignocellulosic biomass.

  18. Microbiological viability of bovine amniotic membrane stored in glycerin 99% at room temperature for 48 months

    Directory of Open Access Journals (Sweden)

    Kelly Cristine de Sousa Pontes

    Full Text Available ABSTRACT The medium for storing biological tissues is of great importance for their optimal use in surgery. Glycerin has been proven efficient for storing diverse tissues for prolonged time, but the preservation of the bovine amniotic membrane in glycerin 99% at room temperature has never been evaluated to be used safely in surgical procedures. This study evaluated the preservation of 80 bovine amniotic membrane samples stored in glycerin 99% at room temperature. The samples were randomly divided evenly into four groups. Samples were microbiologically tested after 1, 6, 12 and 48 months of storage. The presence of bacteria and fungi in the samples was evaluated by inoculation on blood agar and incubation at 37 ºC for 48 hours and on Sabouraud agar at 25 ºC for 5 to 10 days. No fungal or bacterial growth was detected in any of the samples. It was concluded that glycerin is an efficient medium, regarding microbiology, for preserving pre-prepared bovine amniotic membrane, keeping the tissue free of microorganisms that grow in the media up to 48 months at room temperature.

  19. Tunable Curie temperature around room temperature and magnetocaloric effect in ternary Ce-Fe-B amorphous ribbons

    Science.gov (United States)

    Li, Zhu-bai; Zhang, Le-le; Zhang, Xue-feng; Li, Yong-feng; Zhao, Qian; Zhao, Tong-yun; Shen, Bao-gen

    2017-01-01

    Ce13-x Fe81+x B6 (x  =  0, 0.5, 1, 1.5, and 2) amorphous magnets were prepared by melt-spinning method. These magnets are magnetically soft at low temperature, and undergo a second-order phase transition from ferromagnetic to paramagnetic state near room temperature with a broad temperature span. The phase-transition temperature is tunable by the variation of the Ce/Fe atomic ratio, which is mainly due to the change of the coordination number of Fe atoms in these ternary Ce-Fe-B amorphous magnets. Though the entropy change is low, the refrigeration capacities are in the ranges of 116-150 J kg-1 and 319-420 J kg-1, respectively, for the magnetic field changes of 0-2 T and 0-5 T, which is comparable with those of conventional magnetic materials for room-temperature refrigeration. Given the low cost of Fe and Ce, Ce-Fe-B amorphous magnets are attractive magnetic refrigerant candidates.

  20. Optically stimulated luminescence in KCl:Cu x-irradiated at room temperature

    CERN Document Server

    Bandyopadhyay, P K; Chakrabarti, K

    1999-01-01

    Optically stimulated luminescence (OSL) has been observed in single crystals of KCl:Cu x-irradiated at room temperature. It is shown that electrons are liberated from anion sites during the OSL process. The OSL predominantly involves emission due to radiative transition (d s) of monovalent copper ions present in the lattice. The OSL emission shows a strong temperature dependence indicating a thermally assisted process. Electron-hole recombination followed by energy transfer to the Cu activator is suggested as a possible OSL mechanism in KCl:Cu. Preliminary results of OSL in KBr:Cu are also presented.

  1. Liquid-vapor coexistence in a primitive model for a room-temperature ionic liquid.

    Science.gov (United States)

    Martín-Betancourt, Marianela; Romero-Enrique, José M; Rull, Luis F

    2009-07-09

    We present a primitive model for a room-temperature ionic liquid, where the cation is modeled as a charged hard spherocylinder of diameter sigma and length l and the anion as a charged hard sphere of diameter sigma. Liquid-vapor coexistence curves and critical parameters for this model have been studied by grand-canonical Monte Carlo methods. Our results show a decrease of both the critical temperature and density as the cation length l increases. These results are in qualitative agreement with recent experimental estimates of the critical parameters.

  2. Transport properties of room temperature ionic liquids from classical molecular dynamics

    CERN Document Server

    Andreussi, Oliviero

    2012-01-01

    Room Temperature Ionic Liquids (RTILs) have attracted much of the attention of the scientific community in the past decade due the their novel and highly customizable properties. Nonetheless their high viscosities pose serious limitations to the use of RTILs in practical applications. To elucidate some of the physical aspects behind transport properties of RTILs, extensive classical molecular dynamics (MD) calculations are reported. Bulk viscosities and ionic conductivities of butyl-methyl-imidazole based RTILs are presented over a wide range of temperatures. The dependence of the properties of the liquids on simulation parameters, e.g. system size effects and choice of the interaction potential, is analyzed.

  3. SnO2 thin films used as ammonia sensing layers at room temperature

    Directory of Open Access Journals (Sweden)

    Gaddari A.

    2013-09-01

    Full Text Available Gas sensors based on the SnO2 thin films were prepared by dip-coating method starting from their corresponding sols. The as-elaborated thin coatings were afterwards annealed at different temperatures during various times. Their morphology, composition and microstructure were characterized by scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDX and X-ray diffraction (XRD. The results of electrical and sensing measurements indicated that the sensor annealed at 300°C for 3 hours exhibited the best sensitivity towards the detection of NH3 at room temperature.

  4. Room temperature nanojoining of Cu-Ag core-shell nanoparticles and nanowires

    Science.gov (United States)

    Wang, Jiaqi; Shin, Seungha

    2017-02-01

    Room temperature ( T room, 300 K) nanojoining of Ag has been widely employed in fabrication of microelectronic applications where the shapes and structures of microelectronic components must be maintained. In this research, the joining processes of pure Ag nanoparticles (NPs), Cu-Ag core-shell NPs, and nanowires (NWs) are studied using molecular dynamics simulations at T room. The evolution of densification, potential energy, and structural deformation during joining process are analyzed to identify joining mechanisms. Depending on geometry, different joining mechanisms including crystallization-amorphization, reorientation, Shockley partial dislocation are determined. A three-stage joining scenario is observed in both joining process of NPs and NWs. Besides, the Cu core does not participate in all joining processes, however, it enhances the mobility of Ag shell atoms, contributing to a higher densification and bonding strength at T room, compared with pure Ag nanomaterials. The tensile test shows that the nanojoint bears higher rupture strength than the core-shell NW itself. This study deepens understanding in the underlying joining mechanisms and thus nanojoint with desirable thermal, electrical, and mechanical properties could be potentially achieved.

  5. Room temperature ferromagnetism in Fe-doped CuO nanoparticles.

    Science.gov (United States)

    Layek, Samar; Verma, H C

    2013-03-01

    The pure and Fe-doped CuO nanoparticles of the series Cu(1-x)Fe(x)O (x = 0.00, 0.02, 0.04, 0.06 and 0.08) were successfully prepared by a simple low temperature sol-gel method using metal nitrates and citric acid. Rietveld refinement of the X-ray diffraction data showed that all the samples were single phase crystallized in monoclinic structure of space group C2/c with average crystallite size of about 25 nm and unit cell volume decreases with increasing iron doping concentration. TEM micrograph showed nearly spherical shaped agglomerated particles of 4% Fe-doped CuO with average diameter 26 nm. Pure CuO showed weak ferromagnetic behavior at room temperature with coercive field of 67 Oe. The ferromagnetic properties were greatly enhanced with Fe-doping in the CuO matrix. All the doped samples showed ferromagnetism at room temperature with a noticeable coercive field. Saturation magnetization increases with increasing Fe-doping, becomes highest for 4% doping then decreases for further doping which confirms that the ferromagnetism in these nanoparticles are intrinsic and are not resulting from any impurity phases. The ZFC and FC branches of the temperature dependent magnetization (measured in the range of 10-350 K by SQUID magnetometer) look like typical ferromagnetic nanoparticles and indicates that the ferromagnetic Curie temperature is above 350 K.

  6. Room temperature hysteretic spin transition in 1D iron(II) coordination polymers

    Energy Technology Data Exchange (ETDEWEB)

    Dirtu, Marinela M; Naik, Anil D; Marchand-Brynaert, Jacqueline; Garcia, Yann, E-mail: yann.garcia@uclouvain.b [Institut de la Matiere Condensee et des Nanosciences, Universite Catholique de Louvain, Place L. Pasteur 1, 1348, Louvain-la-Neuve (Belgium)

    2010-03-01

    The 1D spin transition compound [Fe(L1){sub 3}](ClO{sub 4}){sub 2} (1) with L1 ethyl-4H-1,2,4-triazol-4-yl-acetate, a novel neutral bidentate ligand, has been synthesised. The temperature dependence of the high-spin molar fraction derived from {sup 57}Fe Mossbauer spectroscopy reveals an exceptionally abrupt single step transition between low-spin and high-spin states with a hysteresis loop of width 5 K (T{sub c}{sup u} = 298 K and T{sub c}{sup {down_arrow}} = 293 K). This spin transition operating around room temperature presents striking reversible thermochromism from white at 295 K to pink at ice temperature, behaving as an optical alert towards temperature variations. This first order phase transition was additionally followed by differential scanning calorimetry in good agreement with Moessbauer spectroscopy data. The spin transition properties of a freshly prepared sample of 1, dried under a N{sub 2}(g) stream which was formulated as [Fe(L1){sub 3}](ClO{sub 4}){sub 2{center_dot}}MeOH (2), are shifted below room temperature (T{sub 1/2}{sup u} = 273 K and T{sub 1/2}{sup {down_arrow}} 263 K), thus showing a remarkable influence of solvent inclusion on the spin state of these chain compounds.

  7. The giant electrocaloric effect in EuTiO{sub 3} nanowires near room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xinyu; Chu, Ruijiang; Dong, Z.C., E-mail: dzc@ntu.edu.cn; Zhong, C.G., E-mail: chgzhong@ntu.edu.cn; Huang, Y.Y.; Min, Y.; Wang, M.; Zhou, P.X.; Yuan, G.Q.; Wei, Shengnan

    2015-11-15

    A phenomenological thermodynamic model is employed to investigate electrocaloric effect in EuTiO{sub 3} nanowires, in which the effects of surface tension, gradient, external stress, nanowires radius and so on are considered. We are surprised that the decrease in size and the increase in external tensile stress can significantly enhance the electrocaloric effect of EuTiO{sub 3} nanowires under the same applied electric filed. Giant adiabatic temperature changes (ΔT = 15–20 K) are achieved near room temperature by controlling the radius of EuTiO{sub 3} nanowires and applied external electric fields, which is much higher than the previous results obtained in many other isomorphic electrocaloric materials. The large electrocaloric effects suggest the potential application for micro-nanodevice in refrigeration. - Highlights: • The giant EC effects (15–20 K) in EuTiO{sub 3} nanowires are revealed for the first time. • The maximum of EC effects at room temperature can be obtained by adjusting radius and external tensile stress. • The adiabatic temperature changes can be enhanced by increasing the change of applied electric fields. • An operating temperature range of more than 100 K has been obtained.

  8. Thermodynamical Evaluation on Magnetocaloric Effect of Magnetic Refrigerating Materials Near Room Temperature

    Institute of Scientific and Technical Information of China (English)

    肖素芬; 陈云贵; 管登高; 杨涛; 涂铭旌

    2003-01-01

    The relationship between isothermal magnetic entropy change ΔS and adiabatic temperature change ΔTad was deduced according to the principles of thermodynamics. The MCE and the engineering application were discussed for Gd and several new kinds of magnetic refrigerating materials near room temperature, Gd5Si2Ge2, MnFeP0.45As0.55 and LaFe11.2Co0.7Si 1.1. Isothermal entropy change is proportional to adiabatic temperature change with a factor of T/C (T is temperature, C is heat capacity). When the comparison of magnetacoloric effect is made for two different mate rials, we should consider isothermal entropy change as well as adiabatic tempera ture change.

  9. Phase diagram of a polariton laser from cryogenic to room temperature

    Science.gov (United States)

    Butté, Raphaël; Levrat, Jacques; Christmann, Gabriel; Feltin, Eric; Carlin, Jean-François; Grandjean, Nicolas

    2009-12-01

    The signature of the strong-coupling regime is unambiguously evidenced in a GaN-based microcavity (MC) above the polariton lasing threshold Pthr at room temperature through the observation of the upper polariton branch. The MC system exhibits a renormalization of the polariton dispersion curve, namely, a reduced normal-mode splitting compared to the low-density regime. Next the dependence of Pthr as a function of exciton-photon detuning is investigated in the 4-340 K temperature range, which allows accessing the polariton lasing phase diagram. The observation of polariton lasing over such a broad range of temperatures reveals a clear transition from a kinetic to a thermodynamic regime with increasing temperature.

  10. Photon antibunching in single-walled carbon nanotubes at telecommunication wavelengths and room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Endo, Takumi, E-mail: endou@az.appi.keio.ac.jp; Ishi-Hayase, Junko; Maki, Hideyuki, E-mail: maki@appi.keio.ac.jp [Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522 (Japan)

    2015-03-16

    We investigated the photoluminescence of individual air-suspended single-walled carbon nanotubes (SWNTs) from 6 to 300 K. Time-resolved and antibunching measurements over the telecommunication wavelength range were performed using a superconducting single-photon detector. We detected moderate temperature independent antibunching behavior over the whole temperature range studied. To investigate the exciton dynamics, which is responsible for the antibunching behavior, we measured excitation-power and temperature dependence of the photoluminescence spectra and lifetime decay curves. These measurements suggested an exciton confinement effect that is likely caused by high-dielectric amorphous carbon surrounding the SWNTs. These results indicate that SWNTs are good candidates for light sources in quantum communication technologies operating in the telecommunication wavelength range and at room temperature.

  11. High Power, Room Temperature Terahertz Emitters Based on Dopant Transitions in 6H-Silicon Carbide

    Institute of Scientific and Technical Information of China (English)

    James Kolodzey; Guang-Chi Xuan; Peng-Cheng Lv; Nathan Sustersic; Xin Ma

    2014-01-01

    Electrically pumped high power terahertz (THz) emitters that operated above room temperature in a pulse mode were fabricated from nitrogen-doped n-type 6H-SiC. The emission spectra had peaks centered on 5 THz and 12 THz (20 meV and 50 meV) that were attributed to radiative transitions of excitons bound to nitrogen donor impurities. Due to the relatively deep binding energies of the nitrogen donors, above 100 meV, and the high thermal conductivity of the SiC substrates, the THz output power and operating temperature were significantly higher than previous dopant based emitters. With peak applied currents of a few amperes, and a top surface area of 1 mm2, the device emitted up to 0.5 mW at liquid nitrogen temperature (77 K), and tens of microwatts up to 333 K. This result is the highest temperature of THz emission reported from impurity-based emitters.

  12. Room temperature ferromagnetism in Cu-doped ZnO synthesized from CuO and ZnO nanoparticles

    Science.gov (United States)

    Owens, Frank J.

    2009-11-01

    AC susceptibility and ferromagnetic resonance (FMR) measurements indicate that ZnO doped with Cu by a simple sintering process starting from nanoparticles of ZnO and CuO is ferromagnetic above room temperature. FMR measurements above room temperature indicate the ordering temperature to be above 520 K. The observation supports the recent theoretical calculations of Huang et al. which predict ferromagnetism in copper-doped ZnO.

  13. Efficient room temperature hydrogen sensor based on UV-activated ZnO nano-network

    Science.gov (United States)

    Kumar, Mohit; Kumar, Rahul; Rajamani, Saravanan; Ranwa, Sapana; Fanetti, Mattia; Valant, Matjaz; Kumar, Mahesh

    2017-09-01

    Room temperature hydrogen sensors were fabricated from Au embedded ZnO nano-networks using a 30 mW GaN ultraviolet LED. The Au-decorated ZnO nano-networks were deposited on a SiO2/Si substrate by a chemical vapour deposition process. X-ray diffraction (XRD) spectrum analysis revealed a hexagonal wurtzite structure of ZnO and presence of Au. The ZnO nanoparticles were interconnected, forming nano-network structures. Au nanoparticles were uniformly distributed on ZnO surfaces, as confirmed by FESEM imaging. Interdigitated electrodes (IDEs) were fabricated on the ZnO nano-networks using optical lithography. Sensor performances were measured with and without UV illumination, at room temperate, with concentrations of hydrogen varying from 5 ppm to 1%. The sensor response was found to be ˜21.5% under UV illumination and 0% without UV at room temperature for low hydrogen concentration of 5 ppm. The UV-photoactivated mode enhanced the adsorption of photo-induced O- and O2- ions, and the d-band electron transition from the Au nanoparticles to ZnO—which increased the chemisorbed reaction between hydrogen and oxygen. The sensor response was also measured at 150 °C (without UV illumination) and found to be ˜18% at 5 ppm. Energy efficient low cost hydrogen sensors can be designed and fabricated with the combination of GaN UV LEDs and ZnO nanostructures.

  14. Room Temperature Antiferromagnetic Ordering of Nanocrystalline Tb1.90Ni0.10O3

    Science.gov (United States)

    Mandal, J.; Dalal, M.; Sarkar, B. J.; Chakrabarti, P. K.

    2017-02-01

    Nanocrystalline Ni-doped terbium oxide (Tb1.90Ni0.10O3) has been synthesized by the co-precipitation method followed by annealing at 700°C for 6 h in vacuum. The crystallographic phase and the substitution of Ni2+ ions in the lattice of Tb2O3 are confirmed by Rietveld analysis of the x-ray diffraction pattern using the software MAUD. High-resolution transmission electron microscopy is also carried out to study the morphology of the sample. Magnetic measurements are carried out at different temperatures from 5 K to 300 K using a superconducting quantum interference device (SQUID) magnetometer. The dependence of the magnetization of Tb1.90Ni0.10O3 as a function of temperature ( M- T) and magnetic field ( M- H) suggests the presence of both paramagnetic and antiferromagnetic phase at room temperature, but antiferromagnetic phase dominates below ˜120 K. The lack of saturation in the M- H curve and good fitting of the M- T curve by the Johnston formula also indicate the presence of both paramagnetic and antiferromagnetic phase at room temperature. Interestingly, an antiferromagnetic to ferromagnetic phase transition is observed below ˜40 K. The result also shows a high value of magnetization at 5 K.

  15. Room-temperature exciton-polaritons with two-dimensional WS2

    Science.gov (United States)

    Flatten, L. C.; He, Z.; Coles, D. M.; Trichet, A. A. P.; Powell, A. W.; Taylor, R. A.; Warner, J. H.; Smith, J. M.

    2016-09-01

    Two-dimensional transition metal dichalcogenides exhibit strong optical transitions with significant potential for optoelectronic devices. In particular they are suited for cavity quantum electrodynamics in which strong coupling leads to polariton formation as a root to realisation of inversionless lasing, polariton condensation and superfluidity. Demonstrations of such strongly correlated phenomena to date have often relied on cryogenic temperatures, high excitation densities and were frequently impaired by strong material disorder. At room-temperature, experiments approaching the strong coupling regime with transition metal dichalcogenides have been reported, but well resolved exciton-polaritons have yet to be achieved. Here we report a study of monolayer WS2 coupled to an open Fabry-Perot cavity at room-temperature, in which polariton eigenstates are unambiguously displayed. In-situ tunability of the cavity length results in a maximal Rabi splitting of ħΩRabi = 70 meV, exceeding the exciton linewidth. Our data are well described by a transfer matrix model appropriate for the large linewidth regime. This work provides a platform towards observing strongly correlated polariton phenomena in compact photonic devices for ambient temperature applications.

  16. Transition-metal-based magnetic refrigerants for room-temperature applications.

    Science.gov (United States)

    Tegus, O; Brück, E; Buschow, K H J; de Boer, F R

    2002-01-10

    Magnetic refrigeration techniques based on the magnetocaloric effect (MCE) have recently been demonstrated as a promising alternative to conventional vapour-cycle refrigeration. In a material displaying the MCE, the alignment of randomly oriented magnetic moments by an external magnetic field results in heating. This heat can then be removed from the MCE material to the ambient atmosphere by heat transfer. If the magnetic field is subsequently turned off, the magnetic moments randomize again, which leads to cooling of the material below the ambient temperature. Here we report the discovery of a large magnetic entropy change in MnFeP0.45As0.55, a material that has a Curie temperature of about 300 K and which allows magnetic refrigeration at room temperature. The magnetic entropy changes reach values of 14.5 J K-1 kg-1 and 18 J K-1 kg-1 for field changes of 2 T and 5 T, respectively. The so-called giant-MCE material Gd5Ge2Si2 (ref. 2) displays similar entropy changes, but can only be used below room temperature. The refrigerant capacity of our material is also significantly greater than that of Gd (ref. 3). The large entropy change is attributed to a field-induced first-order phase transition enhancing the effect of the applied magnetic field.

  17. Inkjet printed, high mobility inorganic-oxide field effect transistors processed at room temperature.

    Science.gov (United States)

    Dasgupta, Subho; Kruk, Robert; Mechau, Norman; Hahn, Horst

    2011-12-27

    Printed electronics (PE) represents any electronic devices, components or circuits that can be processed using modern-day printing techniques. Field-effect transistors (FETs) and logics are being printed with intended applications requiring simple circuitry on large, flexible (e.g., polymer) substrates for low-cost and disposable electronics. Although organic materials have commonly been chosen for their easy printability and low temperature processability, high quality inorganic oxide-semiconductors are also being considered recently. The intrinsic mobility of the inorganic semiconductors are always by far superior than the organic ones; however, the commonly expressed reservations against the inorganic-based printed electronics are due to major issues, such as high processing temperatures and their incompatibility with solution-processing. Here we show a possibility to circumvent these difficulties and demonstrate a room-temperature processed and inkjet printed inorganic-oxide FET where the transistor channel is composed of an interconnected nanoparticle network and a solid polymer electrolyte serves as the dielectric. Even an extremely conservative estimation of the field-effect mobility of such a device yields a value of 0.8 cm(2)/(V s), which is still exceptionally large for a room temperature processed and printed transistor from inorganic materials.

  18. Reversible room-temperature ferromagnetism in Nb-doped SrTiO3 single crystals

    Science.gov (United States)

    Liu, Z. Q.; Lü, W. M.; Lim, S. L.; Qiu, X. P.; Bao, N. N.; Motapothula, M.; Yi, J. B.; Yang, M.; Dhar, S.; Venkatesan, T.; Ariando

    2013-06-01

    The search for oxide-based room-temperature ferromagnetism has been one of the holy grails in condensed matter physics. Room-temperature ferromagnetism observed in Nb-doped SrTiO3 single crystals is reported in this Rapid Communication. The ferromagnetism can be eliminated by air annealing (making the samples predominantly diamagnetic) and can be recovered by subsequent vacuum annealing. The temperature dependence of magnetic moment resembles the temperature dependence of carrier density, indicating that the magnetism is closely related to the free carriers. Our results suggest that the ferromagnetism is induced by oxygen vacancies. In addition, hysteretic magnetoresistance was observed for magnetic field parallel to the current, indicating that the magnetic moments are in the plane of the samples. The x-ray photoemission spectroscopy, the static time-of-flight and the dynamic secondary ion mass spectroscopy and proton induced x-ray emission measurements were performed to examine the magnetic impurities, showing that the observed ferromagnetism is unlikely due to any magnetic contaminant.

  19. Reversible oxygen scavenging at room temperature using electrochemically reduced titanium oxide nanotubes

    Science.gov (United States)

    Close, Thomas; Tulsyan, Gaurav; Diaz, Carlos A.; Weinstein, Steven J.; Richter, Christiaan

    2015-05-01

    A material capable of rapid, reversible molecular oxygen uptake at room temperature is desirable for gas separation and sensing, for technologies that require oxygen storage and oxygen splitting such as fuel cells (solid-oxide fuel cells in particular) and for catalytic applications that require reduced oxygen species (such as removal of organic pollutants in water and oil-spill remediation). To date, however, the lowest reported temperature for a reversible oxygen uptake material is in the range of 200-300 °C, achieved in the transition metal oxides SrCoOx (ref. 1) and LuFe2O4+x (ref. 2) via thermal cycling. Here, we report rapid and reversible oxygen scavenging by TiO2-x nanotubes at room temperature. The uptake and release of oxygen is accomplished by an electrochemical rather than a standard thermal approach. We measure an oxygen uptake rate as high as 14 mmol O2 g-1 min-1, ˜2,400 times greater than commercial, irreversible oxygen scavengers. Such a fast oxygen uptake at a remarkably low temperature suggests a non-typical mechanistic pathway for the re-oxidation of TiO2-x. Modelling the diffusion of oxygen, we show that a likely pathway involves ‘exceptionally mobile’ interstitial oxygen produced by the oxygen adsorption and decomposition dynamics, recently observed on the surface of anatase.

  20. Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival.

    Science.gov (United States)

    Chen, Le; Jian, Shanshan; Bi, Jinhua; Li, Yunlong; Chang, Zhizhou; He, Jian; Ye, Xiaomei

    2016-05-01

    Tomato plant waste (TPW) was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS (total solid) concentrations of 2%, 4% and 6% respectively, at mesophilic (37±1°C) and room (20-25°C) temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416L/kg VS (volatile solids). The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR (polymerase chain reaction) were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA (volatile fatty acid) concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety.

  1. Ambient temperature and emergency room admissions for acute coronary syndrome in Taiwan

    Science.gov (United States)

    Liang, Wen-Miin; Liu, Wen-Pin; Chou, Sze-Yuan; Kuo, Hsien-Wen

    2008-01-01

    Acute coronary syndrome (ACS) is an important public health problem around the world. Since there is a considerable seasonal fluctuation in the incidence of ACS, climatic temperature may have an impact on the onset of this disease. The objective of this study was to assess the relationship between the average daily temperature, diurnal temperature range and emergency room (ER) admissions for ACS in an ER in Taichung City, Taiwan. A longitudinal study was conducted which assessed the correlation of the average daily temperature and the diurnal temperature range to ACS admissions to the ER of the city’s largest hospital. Daily ER admissions for ACS and ambient temperature were collected from 1 January 2000 to 31 March 2003. The Poisson regression model was used in the analysis after adjusting for the effects of holiday, season, and air pollutant concentrations. The results showed that there was a negative significant association between the average daily temperature and ER admissions for ACS. ACS admissions to the ER increased 30% to 70% when the average daily temperature was lower than 26.2°C. A positive association between the diurnal temperature range and ACS admissions was also noted. ACS admissions increased 15% when the diurnal temperature range was over 8.3°C. The data indicate that patients suffering from cardiovascular disease must be made aware of the increased risk posed by lower temperatures and larger changes in temperature. Hospitals and ERs should take into account the increased demand of specific facilities during colder weather and wider temperature variations.

  2. Dry Sliding Wear Behavior of Hafnium-Based Bulk Metallic Glass at Room and Elevated Temperatures

    Science.gov (United States)

    Keshri, Anup Kumar; Behl, Lovish; Lahiri, Debrupa; Dulikravich, George S.; Agarwal, Arvind

    2016-09-01

    Dry sliding wear behavior of hafnium-based bulk metallic glass was studied at two loads (5 and 15 N) and two temperatures (298 and 673 K) using aluminum oxide (Al2O3) ball as a wear counterpart. At 5 N load, wear reduced by ~71% on increasing the temperature from 298 to 673 K. At a higher load of 15 N, the weight loss reduction was much lower (45%) on increasing the temperature from 298 to 673 K. Decreased wear weight loss on increasing the temperature was attributed to the increased hardness of the Hf-based metallic glass at high temperatures. Micro-hardness of the alloy at 293 K was found to be 636 Hv, which gradually increased to 655 Hv on annealing at 673 K. Improvement in the hardness at elevated temperature is attributed to: (1) free volume annihilation, (2) surface oxide formation and (3) nano-crystallites precipitation. Reduced wear at elevated temperature resulted in smaller volume of debris generation that restricted three-body wear to obtain lower coefficient of friction (COF) (0.25-0.35) compared to COF (0.65-0.75) at room temperature.

  3. A temperature relaxation method for the measurement of the specific heat of solids at room temperature in student laboratories

    Science.gov (United States)

    Marín, E.; Delgado-Vasallo, O.; Valiente, H.

    2003-10-01

    A laboratory experiment is described which employs a relaxation method for the measurement of the specific heat at constant pressure of solids at room temperature. The experiment employs measurements of the cooling (or heating) rate of a sample whose temperature differs from that of the surroundings due to light heating. This rate depends on the temperature difference, the specific heat of the sample and the heat transfer coefficient. The sample is suspended adiabatically in a reservoir in which a vacuum can be made. The influence of heat dissipation by convection on the results is discussed for the first time for this kind of experiment. The theoretical aspects related to the described technique involve concepts from several branches of physics that makes the experiment of interest and suitable for students at undergraduate and graduate levels of physics, material sciences and engineering.

  4. Graphene-based, mid-infrared, room-temperature pyroelectric bolometers with ultrahigh temperature coefficient of resistance

    CERN Document Server

    Sassi, U; Nanot, S; Bruna, M; Borini, S; Milana, S; De Fazio, D; Zhuang, Z; Lidorikis, E; Koppens, F H L; Ferrari, A C; Colli, A

    2016-01-01

    Graphene is ideally suited for photonic and optoelectronic applications, with a variety of photodetectors (PDs) in the visible, near-infrared (NIR), and THz reported to date, as well as thermal detectors in the mid-infrared (MIR). Here, we present a room temperature-MIR-PD where the pyroelectric response of a LiNbO3 crystal is transduced with high gain (up to 200) into resistivity modulation for graphene, leading to a temperature coefficient of resistance up to 900%/K, two orders of magnitude higher than the state of the art, for a device area of 300x300um2. This is achieved by fabricating a floating metallic structure that concentrates the charge generated by the pyroelectric substrate on the top-gate capacitor of the graphene channel. This allows us to resolve temperature variations down to 15umK at 1 Hz, paving the way for a new generation of detectors for MIR imaging and spectroscopy

  5. Highly sensitive H2S sensors based on Cu2O/Co3O4 nano/microstructure heteroarrays at and below room temperature

    Science.gov (United States)

    Cui, Guangliang; Zhang, Pinhua; Chen, Li; Wang, Xiaoli; Li, Jianfu; shi, Changmin; Wang, Dongchao

    2017-01-01

    Gas sensors with high sensitivity at and below room temperature, especially below freezing temperature, have been expected for practical application. The lower working temperature of gas sensor is better for the manufacturability, security and environmental protection. Herein, we propose a H2S gas sensor with high sensitivity at and below room temperature, even as low as −30 °C, based on Cu2O/Co3O4 nano/microstructure heteroarrays prepared by 2D electrodeposition technique. This heteroarray was designed to be a multi-barrier system, and which was confirmed by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and scanning probe microscopy. The sensor demonstrates excellent sensitivity, sub-ppm lever detection, fast response, and high activity at low temperature. The enhanced sensing property of sensor was also discussed with the Cu2O/Co3O4 p-p heterojunction barrier modulation and Cu2S conductance channel. We realize the detection of the noxious H2S gas at ultra-low temperature in a more security and environmental protection way. PMID:28252012

  6. Highly sensitive H2S sensors based on Cu2O/Co3O4 nano/microstructure heteroarrays at and below room temperature

    Science.gov (United States)

    Cui, Guangliang; Zhang, Pinhua; Chen, Li; Wang, Xiaoli; Li, Jianfu; Shi, Changmin; Wang, Dongchao

    2017-03-01

    Gas sensors with high sensitivity at and below room temperature, especially below freezing temperature, have been expected for practical application. The lower working temperature of gas sensor is better for the manufacturability, security and environmental protection. Herein, we propose a H2S gas sensor with high sensitivity at and below room temperature, even as low as -30 °C, based on Cu2O/Co3O4 nano/microstructure heteroarrays prepared by 2D electrodeposition technique. This heteroarray was designed to be a multi-barrier system, and which was confirmed by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and scanning probe microscopy. The sensor demonstrates excellent sensitivity, sub-ppm lever detection, fast response, and high activity at low temperature. The enhanced sensing property of sensor was also discussed with the Cu2O/Co3O4 p-p heterojunction barrier modulation and Cu2S conductance channel. We realize the detection of the noxious H2S gas at ultra-low temperature in a more security and environmental protection way.

  7. Evidence for room temperature electric polarization in RMn(2)O(5) multiferroics.

    Science.gov (United States)

    Balédent, V; Chattopadhyay, S; Fertey, P; Lepetit, M B; Greenblatt, M; Wanklyn, B; Saouma, F O; Jang, J I; Foury-Leylekian, P

    2015-03-20

    It is established that the multiferroics RMn(2)O(5) crystallize in the centrosymmetric Pbam space group and that the magnetically induced electric polarization appearing at low temperature is accompanied by a symmetry breaking. However, both our present x-ray study-performed on compounds with R=Pr,Nd,Gd,Tb, and Dy-and first-principles calculations unambiguously rule out this picture. Based on structural refinements, geometry optimization, and physical arguments, we demonstrate in this Letter that the actual space group is likely to be Pm. This turns out to be of crucial importance for RMn(2)O(5) multiferroics since Pm is not centrosymmetric. Ferroelectricity is thus already present at room temperature, and its enhancement at low temperature is a spin-enhanced process. This result is also supported by direct observation of optical second harmonic generation. This fundamental result calls into question the actual theoretical approaches that describe the magnetoelectric coupling in this multiferroic family.

  8. Studies on magnetoelectric coupling in PFN-NZFO composite at room temperature

    Science.gov (United States)

    Pradhan, Dhiren K.; Sahoo, Satyaprakash; Barik, Sujit K.; Puli, Venkata S.; Misra, Pankaj; Katiyar, Ram S.

    2014-05-01

    We report magnetoelectric coupling and Raman spectroscopic studies on [(1 - x)Pb(Fe0.5Nb0.5)O3-xNi0.65Zn0.35Fe2O4] (x = 0.20) PFN-NZFO composite. Apart from the presence of zone centre Raman active modes of the parent compound, some new peaks are observed in the low frequency region. The electric field controlled peak position (˜48 cm-1) suggests that this mode is of magnetic origin. From temperature dependent Raman scattering studies, temperature coefficients for phonons of different symmetries were estimated. Our measurements on electrical control of magnetic order and magnetic control of electrical order confirmed the existence of converse and direct magnetoelectric coupling in this composite at room temperature.

  9. Large room-temperature rotating magnetocaloric effect in NdCo4Al polycrystalline alloy

    Science.gov (United States)

    Hu, Y.; Hu, Q. B.; Wang, C. C.; Cao, Q. Q.; Gao, W. L.; Wang, D. H.; Du, Y. W.

    2017-01-01

    The magnetic refrigeration based on rotating magnetocaloric effect (MCE) is promising to build a simplified magnetic cooling system. Until now, most magnetic refrigerants for rotating MCE are single crystal and work at low temperature, which hinder the development of this refrigeration technology. In present paper, we report a large room-temperature rotating MCE in a magnetic-field-aligned NdCo4Al polycrystalline alloy. A large rotating magnetic entropy change of 1.3 J kg-1 K-1 under 10 kOe and a broad operating temperature window of 52 K are achieved. The origin of large rotating MCE in NdCo4Al polycrystalline alloy and its advantages for rotating magnetic refrigeration are discussed.

  10. Dynamics structure of a room-temperature ionic liquid bmimCl

    Energy Technology Data Exchange (ETDEWEB)

    Inamura, Yasuhiro [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)]. E-mail: inamura@issp.u-tokyo.ac.jp; Yamamuro, Osamu [Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Hayashi, Satoshi [Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Hamaguchi, Hiro-o [Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2006-11-15

    We have measured the neutron scattering from 1-butyl-3-methylimidazolium chloride (bmimCl), which is known as a prototype room temperature ionic liquid. The temperature scan of the elastic neutron scattering showed that glassy bmimCl has a fast {beta} relaxation appearing above T {sub g} as observed in many of molecular and polymer glasses. The quasielastic neutron scattering data of liquid bmimCl showed that the motion of bmim{sup +} ions is regarded as a simple diffusion. The activation energy calculated from the temperature dependence of the self-diffusion coefficients is smaller than that of the intramolecular rotation of butyl-group. This result indicates that bmim{sup +} ion is very flexible and stabilizing the ionic liquids entropically.

  11. Tetragonal phase of epitaxial room-temperature antiferromagnet CuMnAs.

    Science.gov (United States)

    Wadley, P; Novák, V; Campion, R P; Rinaldi, C; Martí, X; Reichlová, H; Zelezný, J; Gazquez, J; Roldan, M A; Varela, M; Khalyavin, D; Langridge, S; Kriegner, D; Máca, F; Mašek, J; Bertacco, R; Holý, V; Rushforth, A W; Edmonds, K W; Gallagher, B L; Foxon, C T; Wunderlich, J; Jungwirth, T

    2013-01-01

    Recent studies have demonstrated the potential of antiferromagnets as the active component in spintronic devices. This is in contrast to their current passive role as pinning layers in hard disk read heads and magnetic memories. Here we report the epitaxial growth of a new high-temperature antiferromagnetic material, tetragonal CuMnAs, which exhibits excellent crystal quality, chemical order and compatibility with existing semiconductor technologies. We demonstrate its growth on the III-V semiconductors GaAs and GaP, and show that the structure is also lattice matched to Si. Neutron diffraction shows collinear antiferromagnetic order with a high Néel temperature. Combined with our demonstration of room-temperature-exchange coupling in a CuMnAs/Fe bilayer, we conclude that tetragonal CuMnAs films are suitable candidate materials for antiferromagnetic spintronics.

  12. Room temperature giant and linear magnetoresistance in topological insulator Bi2Te3 nanosheets.

    Science.gov (United States)

    Wang, Xiaolin; Du, Yi; Dou, Shixue; Zhang, Chao

    2012-06-29

    Topological insulators, a new class of condensed matter having bulk insulating states and gapless metallic surface states, have demonstrated fascinating quantum effects. However, the potential practical applications of the topological insulators are still under exploration worldwide. We demonstrate that nanosheets of a Bi(2)Te(3) topological insulator several quintuple layers thick display giant and linear magnetoresistance. The giant and linear magnetoresistance achieved is as high as over 600% at room temperature, with a trend towards further increase at higher temperatures, as well as being weakly temperature-dependent and linear with the field, without any sign of saturation at measured fields up to 13 T. Furthermore, we observed a magnetic field induced gap below 10 K. The observation of giant and linear magnetoresistance paves the way for 3D topological insulators to be useful for practical applications in magnetoelectronic sensors such as disk reading heads, mechatronics, and other multifunctional electromagnetic applications.

  13. Core-shell nanowire based electrical surface fastener used for room-temperature electronic packaging bonding

    Science.gov (United States)

    Wang, Peng; Ju, Yang; Hosoi, Atsushi

    2014-03-01

    With the ongoing miniaturization in electronic packaging, the traditional solders suffer from severe performance degradation. In addition, the high temperature required in the traditional solder reflow process may damage electronic elements. Therefore, there is an increasing urgent need for a new kind of nontoxic solder that can afford good mechanical stress and electrical contact at low temperature. This paper presents a method of fabricating nanowire surface fastener for the application of microelectronic packaging bonding at room temperature. This surface fastener consists of copper core and polystyrene shell nanowire arrays. It showed an adhesive strength of ˜24 N/cm2 and an electrical resistance of ˜0.41 × 10-2 Ω·cm2. This kind of nanowire surface fastener may enable the exploration of wide range applications, involving assembly of components in the electronic packaging.

  14. Quantitative mid-infrared spectra of allene and propyne from room to high temperatures

    KAUST Repository

    Es-sebbar, Et-touhami

    2014-11-01

    Allene (a-C3H4; CH2CCH2) and propyne (p-C3H4; CH3C2H) have attracted much interest because of their relevance to the photochemistry in astrophysical environments as well as in combustion processes. Both allene and propyne have strong absorption in the infrared region. In the present work, infrared spectra of a-C3H4 and p-C3H4 are measured in the gas phase at temperatures ranging from 296 to 510 K. The spectra are measured over the 580-3400 cm-1 spectral region at resolutions of 0.08 and 0.25 cm-1 using Fourier Transform Infrared spectroscopy. Absolute integrated intensities of the main infrared bands are determined at room temperature and compared with values derived from literature for both molecules. Integrated band intensities are also determined as a function of temperature in various spectral regions.

  15. An atomic clock with $1\\times 10^{-18}$ room-temperature blackbody Stark uncertainty

    CERN Document Server

    Beloy, K; Phillips, N B; Sherman, J A; Schioppo, M; Lehman, J; Feldman, A; Hanssen, L M; Oates, C W; Ludlow, A D

    2014-01-01

    The Stark shift due to blackbody radiation (BBR) is the key factor limiting the performance of many atomic frequency standards, with the BBR environment inside the clock apparatus being difficult to characterize at a high level of precision. Here we demonstrate an in-vacuum radiation shield that furnishes a uniform, well-characterized BBR environment for the atoms in an ytterbium optical lattice clock. Operated at room temperature, this shield enables specification of the BBR environment to a corresponding fractional clock uncertainty contribution of $5.5 \\times 10^{-19}$. Combined with uncertainty in the atomic response, the total uncertainty of the BBR Stark shift is now $1\\times10^{-18}$. Further operation of the shield at elevated temperatures enables a direct measure of the BBR shift temperature dependence and demonstrates consistency between our evaluated BBR environment and the expected atomic response.

  16. Confined Formation of Ultrathin ZnO Nanorods/Reduced Graphene Oxide Mesoporous Nanocomposites for High-Performance Room-Temperature NO2 Sensors.

    Science.gov (United States)

    Xia, Yi; Wang, Jing; Xu, Jian-Long; Li, Xian; Xie, Dan; Xiang, Lan; Komarneni, Sridhar

    2016-12-28

    Here we demonstrate high-performance room-temperature NO2 sensors based on ultrathin ZnO nanorods/reduced graphene oxide (rGO) mesoporous nanocomposites. Ultrathin ZnO nanorods were loaded on rGO nanosheets by a facile two-step additive-free solution synthesis involving anchored seeding followed by oriented growth. The ZnO nanorod diameters were simply controlled by the seed diameters associated with the spatial confinement effects of graphene oxide (GO) nanosheets. Compared to the solely ZnO nanorods and rGO-based sensors, the optimal sensor based on ultrathin ZnO nanorods/rGO nanocomposites exhibited higher sensitivity and quicker p-type response to parts per million level of NO2 at room temperature, and the sensitivity to 1 ppm of NO2 was 119% with the response and recovery time being 75 and 132 s. Moreover, the sensor exhibited full reversibility, excellent selectivity, and a low detection limit (50 ppb) to NO2 at room temperature. In addition to the high transport capability of rGO as well as excellent NO2 adsorption ability derived from ultrathin ZnO nanorods and mesoporous structures, the superior sensing performance of the nanocomposites was attributed to the synergetic effect of ZnO and rGO, which was realized by the electron transfer across the ZnO-rGO interfaces through band energy alignment.

  17. Above room temperature continuous wave operation of a broad-area quantum-cascade laser

    Science.gov (United States)

    Semtsiv, M. P.; Masselink, W. T.

    2016-11-01

    We describe the design and implementation of a broad-area (w ≈ 30 μm) quantum-cascade laser operating in a continuous wave mode up to heat-sink temperatures beyond +100 °C. The room-temperature emission wavelength is 4.6 μm. The temperature gradient in the active region of such a wide laser stripe is essentially perpendicular to the epitaxial layers and the resulting steady-state active region temperature offset scales approximately with the square of the number of cascades. With only 10 cascades in the active region, the threshold electrical power density in the current quantum-cascade laser in the continuous-wave mode is as low as Vth × Ith = 3.8 V × 0.9 kA/cm2 = 3.4 kW/cm2 at room temperature for 2 mm-long two-side high-reflectivity coated laser stripe. A 4 mm-long one-side high-reflectivity coated laser stripe delivers in continuous-wave mode above 0.6 W at +20 °C and above 1.3 W at -27 °C (cooled with a single-stage Peltier element). A 2 mm-long two-side high-reflectivity coated laser stripe demonstrates continuous-wave lasing up to at least +102 °C (375 K). The thermal conductance, Gth, ranges between 235 W/K cm2 and 140 W/K cm2 for temperatures between -33 °C and +102 °C. This demonstration opens the route for continuous-wave power scaling of quantum-cascade lasers via broad-area laser ridges.

  18. Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Phillip [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Agapov, Alexander L [ORNL; Sokolov, Alexei P [ORNL

    2012-01-01

    Using a combination of light scattering techniques and broadband dielectric spectroscopy, we have measured the temperature dependence of structural relaxation time and self diffusion in three imidazolium-based room temperature ionic liquids: [bmim][NTf2], [bmim][PF6], and [bmim][TFA]. A detailed analysis of the results demonstrates that self diffusion decouples from structural relaxation in these systems as the temperature is decreased toward Tg. The degree to which the dynamics are decoupled, however, is shown to be surprisingly weak when compared to other supercooled liquids of similar fragility. In addition to the weak decoupling, we demonstrate that the temperature dependence of the structural relaxation time in all three liquids can be well described by a single Vogel-Fulcher-Tamann function over 13 decades in time from 10 11 s up to 102 s. Furthermore, the stretching of the structural relaxation is shown to be temperature independent over the same range of time scales, i.e., time temperature superposition is valid for these ionic liquids from far above the melting point down to the glass transition temperature.We suggest that these phenomena are interconnected and all result from the same underlying mechanism strong and directional intermolecular interactions.

  19. Prospective comparison of chilled versus room temperature saline irrigation in alcohol-assisted photorefractive keratectomy.

    Science.gov (United States)

    Neuffer, M C; Khalifa, Y M; Moshirfar, M; Miffin, M D

    2013-01-01

    Chilled saline is commonly used to irrigate the ocular surface after photorefractive keratectomy (PRK) and is often considered by the patients to be uncomfortable. Room temperature (non-chilled) saline may be a safe and less painful alternative. To compare pain and visual outcomes after irrigating the ocular surface with chilled saline versus room temperature saline in alcohol assisted PRK. In this prospective, single-masked, randomized, contralateral eye study, myopic eyes were treated with PRK. Immediately after laser ablation one eye was irrigated with chilled saline and the other with non-chilled saline. Primary outcomes measured were pain, haze, uncorrected (UCVA) and best-corrected (BCVA) visual acuities, and manifest refraction. Each group comprised of 40 eyes. There was no significant difference in pain between the groups at any point during five days after surgery. At 6 months the mean UCVA was -0.08 logMAR ± .077 [SD] (20/17) and -0.07 ± .074 logMAR (20/17) in the chilled and non-chilled groups respectively (p =.35). Both groups achieved 95% UCVA of 20/20 or better. The manifest refraction spherical equivalent (MRSE) was -0.05 ± 0.21 D and -0.025 ± 0.27 D respectively (p = .79). There were no lines lost of BCVA and no haze observed. Similar outcomes were observed with regard to pain and vision in both groups. The use of room temperature saline irrigation during PRK appears to be safe and effective. © NEPjOPH.

  20. Ripening and shelf life of 'BRS Caipira' banana fruit stored under room temperature or refrigeration

    Directory of Open Access Journals (Sweden)

    Orjana Santos Lima

    2014-04-01

    Full Text Available BRS Caipira variety, internationally known as 'Yangambi km 5', is an alternative to meet the demand of 'Maçã'-type fruit due to its resistance to Panama disease. This study had the objective of generating information about 'BRS Caipira' fruit ripening and cold storage potential. For the ripening study fruits were stored under room temperature conditions (25±2°C / 58±6% U.R. and assessed for postharvest life evaluation and characterization of seven maturity stages based on peel color: completely green - MS1; green with yellow traces - MS2; more green than yellow - MS3; more yellow than green - MS4; yellow with green tips - MS5; completely yellow - MS6; yellow with brown spots - MS7. For the cold storage potential study, fruits at MS1 were cold stored (14±1°C / 53±2% U.R. for 28 days. Weekly, fruits were transferred to room temperature to ripen until MS6 when were assessed for quality attributes. Ripening of 'BRS Caipira' fruit was characterized as slow between MS1 and MS2 (averaging five days, then fast between MS2 and MS6 (up to four days in average, and undergoing determinant changes between MS6 and MS7: pulp yield reached 80%, titratable acidity reduced by 50% and ratio increased by 78%. Cold storage extended shelf life by up to 19 days as compared with control, without visible symptoms of chilling injury, although tends to reduce soluble solids in ripe fruit. Maximum recommended time for storage of 'BRS Caipira' fruit at 14°C is 21 days, since it allows a few more days under room temperature until fruit reach MS6.

  1. Neurobehavioral approach for evaluation of office workers' productivity: The effects of room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Li; Lian, Zhiwei; Pan, Li [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Ye, Qian [Shanghai Research Institute of Building Science, Shanghai 200041 (China)

    2009-08-15

    Indoor environment quality has great influence on worker's productivity, and how to assess the effect of indoor environment on productivity remains to be the major challenge. A neurobehavioral approach was proposed for evaluation of office workers' productivity in this paper. The distinguishing characteristic of neurobehavioral approach is its emphasis on the identification and measurement of behavioral changes, for the influence of environment on brain functions manifests behaviorally. Therefore worker's productivity can be comprehensively evaluated by testing the neurobehavioral functions. Four neurobehavioral functions, including perception, learning and memory, thinking, and executive functions were measured with nine representative psychometric tests. The effect of room temperature on performance of neurobehavioral tests was investigated in the laboratory. Four temperatures (19 C, 24 C, 27 C, and 32 C) were investigated based on the thermal sensation from cold to hot. Signal detection theory was utilized to analyze response bias. It was found that motivated people could maintain high performance for a short time under adverse (hot or cold) environmental conditions. Room temperature affected task performance differentially, depending on the type of tasks. The proposed neurobehavioral approach could be worked to quantitatively and systematically evaluate office workers' productivity. (author)

  2. Mechanical Properties of Discontinuous Precipitated Al-Zn Alloys after Drawing at Room and Cryogenic Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Soo; Lee, Jehyun [Changwon National University, Changwon (Korea, Republic of); Han, Seung Zeon; Ahn, Jee Hyuk [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lim, Sung Hwan [Kangwon National University, Chuncheon (Korea, Republic of); Kim, Kwang Ho [Pusan National University, Pusan (Korea, Republic of); Kim, Sang sik [Gyeongsang National University, Jinju (Korea, Republic of)

    2017-02-15

    In order to study the effect of microstructural change on the tensile properties of discontinuous precipitated Al-Zn binary alloy, four different Al-Zn alloys(25, 30, 35, 45 wt%Zn) were aged at 160 ℃ for different aging times(0, 5, 15, 30, 60, 120, 360 min) after being solution treated at 400 ℃, and successively drawn at room and cryogenic temperatures(-197 ℃). Discontinuous precipitation was formed during aging in the Al matrix(which contained more than 30 wt%Zn) in Al alloys containing more than 30 wt%Zn. The tensile strength of continuous precipitated Al-35Zn alloy decreased with increasing drawing ratio, however, the tensile strength of discontinuous precipitated Al-35Zn alloy increased with further drawing. The strength and ductility combination, 350 MPa-36%was achieved by drawning discontinuous precipitated Al-Zn alloy at room temperature. The discontinuous precipitated Al-Zn alloy drawn at cryogenic temperature showed a higher value of tensile strength, over 500 MPa, although ductility decreased.

  3. Room Temperature Ion-Beam-Induced Recrystallization and Large Scale Nanopatterning.

    Science.gov (United States)

    Satpati, Biswarup; Ghosh, Tanmay

    2015-02-01

    We have studied ion-induced effects in the near-surface region of two eutectic systems. Gold and Silver nanodots on Silicon (100) substrate were prepared by thermal evaporation under high vacuum condition at room temperature (RT) and irradiated with 1.5 MeV Au2+ ions at flux ~1.25 x 10(11) ions cm-2 s-1 also at RT. These samples were characterized using cross-sectional transmission electron microscopy (XTEM) and associated techniques. We have observed that gold act as catalysis in the recrystallization process of ion-beam-induced amorphous Si at room temperature and also large mass transport up to a distance of about 60 nm into the substrate. Mass transport is much beyond the size (~ 6-20 nm) of these Au nanodots. Ag nanoparticles with diameter 15-45 nm are half-way embedded into the Si substrate and does not stimulate in recrystallization. In case of Au nanoparticles upon ion irradiation, mixed phase formed only when the local composition and transient temperature during irradiation is sufficient to cause mixing in accordance with the Au-Si stable phase diagram. Spectroscopic imaging in the scanning TEM using spatially resolved electron energy loss spectroscopy provides one of the few ways to measure the real-space nanoscale mixing.

  4. Room air temperature affects occupants' physiology, perceptions and mental alertness

    Energy Technology Data Exchange (ETDEWEB)

    Tham, Kwok Wai; Willem, Henry Cahyadi [Department of Building, School of Design and Environment, National University of Singapore, 4 Architecture Drive, Singapore 117566 (Singapore)

    2010-01-15

    Thermal environment that causes thermal discomfort may affect office work performance. However, the mechanisms through which occupants are affected are not well understood. This study explores the plausible mechanism linking room air temperature and mental alertness through perceptual and physiological responses in the tropics. Ninety-six young adults participated as voluntary subjects in a series of experiment conducted in the simulated office settings. Three room air temperatures, i.e. 20.0, 23.0 and 26.0 C were selected as the experimental conditions. Both thermal comfort and thermal sensation changed significantly with time under all exposures (P < 0.0001). Longer exposure at 20.0 C led to cooling sensations due to lower skin temperatures (P < 0.0001) and was perceived as the least comfortable. Nevertheless, this moderate cold exposure induced nervous system activation as demonstrated by the increase of {alpha}-Amylase level (P < 0.0001) and the Tsai-partington test (P < 0.0001). A mechanism linking thermal environment, occupants' responses and performance is proposed. (author)

  5. Room-Temperature Oxidation of Formaldehyde by Layered Manganese Oxide: Effect of Water.

    Science.gov (United States)

    Wang, Jinlong; Zhang, Pengyi; Li, Jinge; Jiang, Chuanjia; Yunus, Rizwangul; Kim, Jeonghyun

    2015-10-20

    Layered manganese oxide, i.e., birnessite was prepared via the reaction of potassium permanganate with ammonium oxalate. The water content in the birnessite was adjusted by drying/calcining the samples at various temperatures (30 °C, 100 °C, 200 °C, 300 °C, and 500 °C). Thermogravimetry-mass spectroscopy showed three types of water released from birnessite, which can be ascribed to physically adsorbed H2O, interlayer H2O and hydroxyl, respectively. The activity of birnessite for formaldehyde oxidation was positively associated with its water content, i.e., the higher the water content, the better activity it has. In-situ DRIFTS and step scanning XRD analysis indicate that adsorbed formaldehyde, which is promoted by bonded water via hydrogen bonding, is transformed into formate and carbonate with the consumption of hydroxyl and bonded water. Both bonded water and water in air can compensate the consumed hydroxyl groups to sustain the mineralization of formaldehyde at room temperature. In addition, water in air stimulates the desorption of carbonate via water competitive adsorption, and accordingly the birnessite recovers its activity. This investigation elucidated the role of water in oxidizing formaldehyde by layered manganese oxides at room temperature, which may be helpful for the development of more efficient materials.

  6. Ultrabright single-photon source on diamond with electrical pumping at room and high temperatures

    Science.gov (United States)

    Fedyanin, D. Yu; Agio, M.

    2016-07-01

    The recently demonstrated electroluminescence of color centers in diamond makes them one of the best candidates for room temperature single-photon sources. However, the reported emission rates are far off what can be achieved by state-of-the-art electrically driven epitaxial quantum dots. Since the electroluminescence mechanism has not yet been elucidated, it is not clear to what extent the emission rate can be increased. Here we develop a theoretical framework to study single-photon emission from color centers in diamond under electrical pumping. The proposed model comprises electron and hole trapping and releasing, transitions between the ground and excited states of the color center as well as structural transformations of the center due to carrier trapping. It provides the possibility to predict both the photon emission rate and the wavelength of emitted photons. Self-consistent numerical simulations of the single-photon emitting diode based on the proposed model show that the photon emission rate can be as high as 100 kcounts s-1 at standard conditions. In contrast to most optoelectronic devices, the emission rate steadily increases with the device temperature achieving of more than 100 Mcount s-1 at 500 K, which is highly advantageous for practical applications. These results demonstrate the potential of color centers in diamond as electrically driven non-classical light emitters and provide a foundation for the design and development of single-photon sources for optical quantum computation and quantum communication networks operating at room and higher temperatures.

  7. A Novel Lipid Extraction Method from Wet Microalga Picochlorum sp. at Room Temperature

    Directory of Open Access Journals (Sweden)

    Fangfang Yang

    2014-03-01

    Full Text Available A novel method using ethanol was proposed for extracting lipids from wet microalga Picochlorum sp. at room temperature and pressure. In this study, Central Composite design (CCD was applied to investigate the optimum conditions of lipid extraction. The results revealed that the solvent to biomass ratio had the largest effect on lipid extraction efficiency, followed by extraction time and temperature. A high lipid extraction yield (33.04% of the dry weight was obtained under the following extraction conditions: 5 mL solvents per gram of wet biomass for 37 min with gentle stirring at room temperature. The extraction yield was comparable to that obtained by the widely used Bligh-Dyer method. Furthermore, no significant differences in the distribution of lipid classes and fatty acid composition were observed according to different extraction methods. In conclusion, these results indicated that the proposed procedure using ethanol could extract lipids from wet biomass efficiently and had giant potential for lipid extraction at large scale.

  8. Room-temperature near-infrared electroluminescence from boron-diffused silicon pn junction diodes

    Directory of Open Access Journals (Sweden)

    Si eLi

    2015-02-01

    Full Text Available Silicon pn junction diodes with different doping concentrations were prepared by boron diffusion into Czochralski (CZ n-type silicon substrate. Their room-temperature near-infrared electroluminescence (EL was measured. In the EL spectra of the heavily boron doped diode, a luminescence peak at ~1.6 m (0.78 eV was observed besides the band-to-band line (~1.1eV under the condition of high current injection, while in that of the lightly boron doped diode only the band-to-band line was observed. The intensity of peak at 0.78 eV increases exponentially with current injection with no observable saturation at room temperature. Furthermore, no dislocations were found in the cross-sectional transmission electron microscopy image, and no dislocation-related luminescence was observed in the low-temperature photoluminescence spectra. We deduce the 0.78 eV emission originates from the irradiative recombination in the strain region of diodes caused by the diffusion of large number of boron atoms into silicon crystal lattice.

  9. Hollow V₂O₅ Nanoassemblies for High-Performance Room-Temperature Hydrogen Sensors.

    Science.gov (United States)

    Wang, Ying-Ting; Whang, Wha-Tzong; Chen, Chun-Hua

    2015-04-29

    Nanostructured oxides with characteristic morphologies are essential building blocks for high-performance gas-sensing devices. We describe the high-yield fabrication of a series of functionalized V2O5 nanoassemblies through a facile polyol approach with specific varieties of polyvinylpyrrolidone. The synthesized V2O5 nanoassemblies consisting of tiny one-dimensional nanoblocks with the absence of any extrinsic catalysts exhibit distinct hemispherical or spherical hollow morphologies and operate as room-temperature hydrogen sensors with remarkable sensitivities and responses.

  10. Copper Selenide Nanosnakes: Bovine Serum Albumin-Assisted Room Temperature Controllable Synthesis and Characterization

    OpenAIRE

    Huang Peng; Kong Yifei; Li Zhiming; Gao Feng; Cui Daxiang

    2010-01-01

    Abstract Herein we firstly reported a simple, environment-friendly, controllable synthetic method of CuSe nanosnakes at room temperature using copper salts and sodium selenosulfate as the reactants, and bovine serum albumin (BSA) as foaming agent. As the amounts of selenide ions (Se2−) released from Na2SeSO3 in the solution increased, the cubic and snake-like CuSe nanostructures were formed gradually, the cubic nanostructures were captured by the CuSe nanosnakes, the CuSe nanosnakes gre...

  11. Room Temperature Bubble Point Tests on Porous Screens: Implications for Cryogenic Liquid Acquisition Devices

    Science.gov (United States)

    Hartwig, Jason; Mann, J. Adin, Jr.

    2012-01-01

    We present experimental results for room temperature bubble point tests conducted at the Cedar Creek Road Cryogenic Complex, Cell 7 (CCL-7) at the NASA Glenn Research Center. The purpose of these tests was to investigate the performance of three different fine mesh screens in room temperature liquids to provide pretest predictions in cryogenic liquid nitrogen (LN2) and hydrogen (LH2) as part of NASA's microgravity LAD technology development program. Bench type tests based on the maximum bubble point method were conducted for a 325 x 2300, 450 x 2750, and 510 x 3600 mesh sample in pure room temperature liquid methanol, acetone, isopropyl alcohol, water, and mixtures of methanol and water to cover the intermediate to upper surface tension range. A theoretical model for the bubble point pressure is derived from the Young-LaPlace equation for the pressure drop across a curved interface. Governing equations are reduced in complexity through a set of simplifying assumptions to permit direct comparison with the experimental data. Screen pore sizes are estimated from scanning electron microscopy (SEM) to make pretest predictions. Pore sizes based on SEM analysis are compared with historical data available in the literature for the 325 x 2300 and 450 x 2750 screens as well with data obtained from bubble point tests conducted in this work. Experimental results show that bubble point pressure is proportional to the surface tension of the liquid. We show that there is excellent agreement between data and model for pure fluids when the data is corrected for non-zero contact angle measured on the screens using a modified Sessile Drop technique. SEM image analysis of the three meshes indicated that bubble point pressure would be a maximum for the finest mesh screen. The pore diameters based on SEM analysis and experimental data obtained here are in excellent agreement for the 325 x 2300 and 450 x 2750 meshes, but not for the finest 510 x 3600 mesh. Therefore the simplified model

  12. Ge-Based Spin-Photodiodes for Room-Temperature Integrated Detection of Photon Helicity

    KAUST Repository

    Rinaldi, Christian

    2012-05-02

    Spin-photodiodes based on Fe/MgO/Ge(001) heterostructures are reported. These devices perform the room-temperature integrated electrical detection of the spin polarization of a photocurrent generated by circularly polarized photons with a wavelength of 1300 nm, for light pulses with intensity I 0 down to 200 μW. A forward and reverse-biased average photocurrent variation of 5.9% is measured for the complete reversal of the incident light helicity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Use of personalized ventilation for improving health, comfort, and performance at high room temperature and humidity

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Skwarczynski, Mariusz; Kaczmarczyk, J.

    2013-01-01

    to assess their performance. Objective measures of tear film stability, concentration of stress biomarkers in saliva, and eye blinking rate were taken. Using PV significantly improved the perceived air quality (PAQ) and thermal sensation and decreased the intensity of Sick Building Syndrome (SBS) symptoms...... to those prevailing in a comfortable room environment without PV. Self-estimated and objectively measured performance was improved. Increasing the temperature and relative humidity, but not the use of PV, significantly decreased tear film quality and the concentration of salivary alpha-amylase, indicating...

  14. Room temperature spin relaxation length in spin light-emitting diodes

    Science.gov (United States)

    Soldat, Henning; Li, Mingyuan; Gerhardt, Nils C.; Hofmann, Martin R.; Ludwig, Arne; Ebbing, Astrid; Reuter, Dirk; Wieck, Andreas D.; Stromberg, Frank; Keune, Werner; Wende, Heiko

    2011-08-01

    We investigate the spin relaxation length in GaAs spin light-emitting diode devices under drift transport at room temperature. The spin-polarised electrons are injected through a MgO tunnel barrier from a Fe/Tb multilayer in magnetic remanence. The decrease in circular polarization with increasing injection path length is investigated and found to be exponential, supporting drift-based transport. The spin relaxation length in our samples is 26 nm, and a lower bound for the spin injection efficiency at the spin injector/GaAs interface is estimated to be 25 ± 2%.

  15. Crack-growth behavior in thick welded plates of Inconel 718 at room and cryogenic temperatures

    Science.gov (United States)

    Forman, R. G.

    1974-01-01

    Results of mechanical-properties and axial-load fatigue and fracture tests performed on thick welded plates of Inconel 718 superalloy are presented. The test objectives were to determine the tensile strength properties and the crack-growth behavior in electron-beam, plasma-arc, and gas tungsten are welds for plates 1.90 cm (0.75 in) thick. Base-metal specimens were also tested to determine the flaw-growth behavior. The tests were performed in room-temperature-air and liquid nitrogen environments. The experimental crack-growth-rate data are correlated with theoretical crack-growth-rate predictions for semielliptical surface flaws.

  16. Room-temperature operation of mid-infrared surface-plasmon quantum cascade lasers

    Science.gov (United States)

    Bahriz, M.; Moreau, V.; Palomo, J.; Krysa, A. B.; Austin, D.; Cockburn, J. W.; Roberts, J. S.; Wilson, L. R.; Julien, F.; Colombelli, R.

    2007-04-01

    We report the pulsed, room-temperature operation of an InGaAs/AllnAs quantum cascade laser at an operating wavelength of ≈ 7.5 μm in which the optical mode is a surface-plasmon polariton excitation. The use of a silver-based electrical contact with reduced optical losses at the laser emission wavelength allows for a reduction of the laser threshold current by a factor of two relative to samples with a gold-based contact layer.

  17. Optomechanically induced transparency in a membrane-in-the-middle setup at room temperature

    Science.gov (United States)

    Karuza, M.; Biancofiore, C.; Bawaj, M.; Molinelli, C.; Galassi, M.; Natali, R.; Tombesi, P.; Di Giuseppe, G.; Vitali, D.

    2013-07-01

    We demonstrate the analog of electromagnetically induced transparency in a room temperature cavity optomechanics setup formed by a thin semitransparent membrane within a Fabry-Pérot cavity. Due to destructive interference, a weak probe field is completely reflected by the cavity when the pump beam is resonant with the motional red sideband of the cavity. Under this condition we infer a significant slowing down of light of hundreds of microseconds, which is easily tuned by shifting the membrane along the cavity axis. We also observe the associated phenomenon of electromagnetically induced amplification which occurs due to constructive interference when the pump is resonant with the blue sideband.

  18. Transforming from paramagnetism to room temperature ferromagnetism in CuO by ball milling

    Directory of Open Access Journals (Sweden)

    Daqiang Gao

    2011-12-01

    Full Text Available In this work, we experimentally demonstrate that it is possible to induce ferromagnetism in CuO by ball milling without any ferromagnetic dopant. The magnetic measurements indicate that paramagnetic CuO is driven to the ferromagnetic state at room temperature by ball milling gradually. The saturation magnetization of the milled powders is found to increase with expanding the milling time and then decrease by annealing under atmosphere. The fitted X-ray photoelectron spectroscopy results indicate that the observed induction and weaken of the ferromagnetism shows close relationship with the valence charged oxygen vacancies (Cu1+-VO in CuO.

  19. Thin, Flexible Supercapacitors Made from Carbon Nanofiber Electrodes Decorated at Room Temperature with Manganese Oxide Nanosheets

    Directory of Open Access Journals (Sweden)

    S. K. Nataraj

    2013-01-01

    Full Text Available We report the fabrication and electrochemical performance of a flexible thin film supercapacitor with a novel nanostructured composite electrode. The electrode was prepared by in situ coprecipitation of two-dimensional (2D MnO2 nanosheets at room temperature in the presence of carbon nanofibers (CNFs. The highest specific capacitance of 142 F/g was achieved for CNFs-MnO2 electrodes in sandwiched assembly with PVA-H4SiW12O40·nH2O polyelectrolyte separator.

  20. Transistor Effects and in situ STM of Redox Molecules at Room Temperature

    DEFF Research Database (Denmark)

    Albrecht, T.; Guckian, A.; Ulstrup, Jens

    2004-01-01

    Inorganic transition metal complexes were identified as potential candidates for transistor-like behaviour in an electrochemical STM configuration at room temperature. The theoretical background has been established based on condensed matter charge transfer theory. It predicts a distinct increase...... of the tunnelling current close to the equilibrium potential, i.e. if molecular bridge states are tuned into resonance with the Fermi levels of the enclosing electrodes. The complexes display robust electrochemistry on Au(111) electrode surfaces. STM images at molecular resolution give detailed insight...... into the surface structure. STS experiments are on the way to probe putative transistor-like behaviour....