WorldWideScience

Sample records for stable room temperature

  1. Stable room-temperature thallium bromide semiconductor radiation detectors

    Science.gov (United States)

    Datta, A.; Fiala, J.; Becla, P.; Motakef, Shariar

    2017-10-01

    Thallium bromide (TlBr) is a highly efficient ionic semiconductor with excellent radiation detection properties. However, at room temperature, TlBr devices polarize under an applied electric field. This phenomenon not only degrades the charge collection efficiency of the detectors but also promotes chemical reaction of the metal electrodes with bromine, resulting in an unstable electric field and premature failure of the device. This drawback has been crippling the TlBr semiconductor radiation detector technology over the past few decades. In this exhaustive study, this polarization phenomenon has been counteracted using innovative bias polarity switching schemes. Here the highly mobile Br- species, with an estimated electro-diffusion velocity of 10-8 cm/s, face opposing electro-migration forces during every polarity switch. This minimizes the device polarization and availability of Br- ions near the metal electrode. Our results indicate that it is possible to achieve longer device lifetimes spanning more than 17 000 h (five years of 8 × 7 operation) for planar and pixelated radiation detectors using this technique. On the other hand, at constant bias, 2500 h is the longest reported lifetime with most devices less than 1000 h. After testing several biasing switching schemes, it is concluded that the critical bias switching frequency at an applied bias of 1000 V/cm is about 17 μHz. Using this groundbreaking result, it will now be possible to deploy this highly efficient room temperature semiconductor material for field applications in homeland security, medical imaging, and physics research.

  2. Stable room-temperature thallium bromide semiconductor radiation detectors

    Directory of Open Access Journals (Sweden)

    A. Datta

    2017-10-01

    Full Text Available Thallium bromide (TlBr is a highly efficient ionic semiconductor with excellent radiation detection properties. However, at room temperature, TlBr devices polarize under an applied electric field. This phenomenon not only degrades the charge collection efficiency of the detectors but also promotes chemical reaction of the metal electrodes with bromine, resulting in an unstable electric field and premature failure of the device. This drawback has been crippling the TlBr semiconductor radiation detector technology over the past few decades. In this exhaustive study, this polarization phenomenon has been counteracted using innovative bias polarity switching schemes. Here the highly mobile Br− species, with an estimated electro-diffusion velocity of 10−8 cm/s, face opposing electro-migration forces during every polarity switch. This minimizes the device polarization and availability of Br− ions near the metal electrode. Our results indicate that it is possible to achieve longer device lifetimes spanning more than 17 000 h (five years of 8 × 7 operation for planar and pixelated radiation detectors using this technique. On the other hand, at constant bias, 2500 h is the longest reported lifetime with most devices less than 1000 h. After testing several biasing switching schemes, it is concluded that the critical bias switching frequency at an applied bias of 1000 V/cm is about 17 μHz. Using this groundbreaking result, it will now be possible to deploy this highly efficient room temperature semiconductor material for field applications in homeland security, medical imaging, and physics research.

  3. Room temperature stable CO x -free H2production 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 CO 2 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/CO 2 -free H 2 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 H 2 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.

  4. Room temperature bioproduction, isolation and anti-microbial properties of stable elemental copper nanoparticles.

    Science.gov (United States)

    Pantidos, Nikolaos; Edmundson, Matthew C; Horsfall, Louise

    2018-01-25

    In nanoparticle production there are a number of important considerations that must be made. Producing nanoparticles of uniform size and shape is vital, but no less important is ensuring the production process is as efficient as possible in time, cost and energy. Traditional chemical and physical methods of nanoparticle production often involve high temperatures and pressures, as well as the use of toxic substrates; in contrast the bioproduction of nanoparticles is greener and requires a smaller input of energy resources. Here we outline a method for the straightforward bioproduction of stable, uniform elemental (zero-valent) copper nanoparticles at room temperature, and demonstrate how their size and shape can be modified by subsequent pH manipulation. We also highlight a potential application for these biogenic copper nanoparticles by demonstrating their potential to inhibit bacterial growth. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  5. Room Temperature Stable PspA-Based Nanovaccine Induces Protective Immunity

    Directory of Open Access Journals (Sweden)

    Danielle A. Wagner-Muñiz

    2018-03-01

    Full Text Available Streptococcus pneumoniae is a major causative agent of pneumonia, a debilitating disease particularly in young and elderly populations, and is the leading worldwide cause of death in children under the age of five. While there are existing vaccines against S. pneumoniae, none are protective across all serotypes. Pneumococcal surface protein A (PspA, a key virulence factor of S. pneumoniae, is an antigen that may be incorporated into future vaccines to address the immunological challenges presented by the diversity of capsular antigens. PspA has been shown to be immunogenic and capable of initiating a humoral immune response that is reactive across approximately 94% of pneumococcal strains. Biodegradable polyanhydrides have been studied as a nanoparticle-based vaccine (i.e., nanovaccine platform to stabilize labile proteins, to provide adjuvanticity, and enhance patient compliance by providing protective immunity in a single dose. In this study, we designed a room temperature stable PspA-based polyanhydride nanovaccine that eliminated the need for a free protein component (i.e., 100% encapsulated within the nanoparticles. Mice were immunized once with the lead nanovaccine and upon challenge, presented significantly higher survival rates than animals immunized with soluble protein alone, even with a 25-fold reduction in protein dose. This lead nanovaccine formulation performed similarly to protein adjuvanted with Alum, however, with much less tissue reactogenicity at the site of immunization. By eliminating the free PspA from the nanovaccine formulation, the lead nanovaccine was efficacious after being stored dry for 60 days at room temperature, breaking the need for maintaining the cold chain. Altogether, this study demonstrated that a single dose PspA-based nanovaccine against S. pneumoniae induced protective immunity and provided thermal stability when stored at room temperature for at least 60 days.

  6. Room temperature stable COx-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.

    2016-01-01

    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 COx-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. PMID:28508036

  7. Proinsulin is stable at room temperature for 24 hours in EDTA: A clinical laboratory analysis (adAPT 3.

    Directory of Open Access Journals (Sweden)

    Jane Davidson

    Full Text Available Reference laboratories advise immediate separation and freezing of samples for the assay of proinsulin, which limit its practicability for smaller centres. Following the demonstration that insulin and C-peptide are stable in EDTA at room temperature for at least 24hours, we undertook simple stability studies to establish whether the same might apply to proinsulin.Venous blood samples were drawn from six adult women, some fasting, some not, aliquoted and assayed immediately and after storage at either 4°C or ambient temperature for periods from 2h to 24h.There was no significant variation or difference with storage time or storage condition in either individual or group analysis.Proinsulin appears to be stable at room temperature in EDTA for at least 24h. Immediate separation and storage on ice of samples for proinsulin assay is not necessary, which will simplify sample transport, particularly for multicentre trials.

  8. Recoil Induced Room Temperature Stable Frenkel Pairs in a-Hafnium Upon Thermal Neutron Capture

    Science.gov (United States)

    Butz, Tilman; Das, Satyendra K.; Dey, Chandi C.; Ghoshal, Shamik

    2013-11-01

    Ultrapure hafnium metal (110 ppm zirconium) was neutron activated with a thermal neutron flux of 6:6 · 1012 cm-2s-1 in order to obtain 181Hf for subsequent time differential perturbed angular correlation (TDPAC) experiments using the nuclear probe 181Hf(β-) 181Ta. Apart from the expected nuclear quadrupole interaction (NQI) signal for a hexagonal close-packed (hcp) metal, three further discrete NQIs were observed with a few percent fraction each. The TDPAC spectra were recorded for up to 11 half lives with extreme statistical accuracy. The fitted parameters vary slightly within the temperature range between 248 K and 373 K. The signals corresponding to the three additional sites completely disappear after `annealing' at 453 K for one minute. Based on the symmetry of the additional NQIs and their temperature dependencies, they are tentatively attributed to Frenkel pairs produced by recoil due to the emission of a prompt 5:694 MeV -ray following thermal neutron capture and reported by the nuclear probe in three different positions. These Frenkel pairs are stable up to at least 373 K.

  9. Direct Observation of Room-Temperature Stable Magnetism in LaAlO3/SrTiO3 Heterostructures.

    Science.gov (United States)

    Yang, Ming; Ariando; Zhou, Jun; Asmara, Teguh Citra; Krüger, Peter; Yu, Xiao Jiang; Wang, Xiao; Sanchez-Hanke, Cecilia; Feng, Yuan Ping; Venkatesan, T; Rusydi, Andrivo

    2018-03-21

    Along with an unexpected conducting interface between nonmagnetic insulating perovskites LaAlO 3 and SrTiO 3 (LaAlO 3 /SrTiO 3 ), striking interfacial magnetisms have been observed in LaAlO 3 /SrTiO 3 heterostructures. Interestingly, the strength of the interfacial magnetic moment is found to be dependent on oxygen partial pressures during the growth process. This raises an important, fundamental question on the origin of these remarkable interfacial magnetic orderings. Here, we report a direct evidence of room-temperature stable magnetism in a LaAlO 3 /SrTiO 3 heterostructure prepared at high oxygen partial pressure by using element-specific soft X-ray magnetic circular dichroism at both Ti L 3,2 and O K edges. By combining X-ray absorption spectroscopy at both Ti L 3,2 and O K edges and first-principles calculations, we qualitatively ascribe that this strong magnetic ordering with dominant interfacial Ti 3+ character is due to the coexistence of LaAlO 3 surface oxygen vacancies and interfacial (Ti Al -Al Ti ) antisite defects. On the basis of this new understanding, we revisit the origin of the weak magnetism in LaAlO 3 /SrTiO 3 heterostructures prepared at low oxygen partial pressures. Our calculations show that LaAlO 3 surface oxygen vacancies are responsible for the weak magnetism at the interface. Our result provides direct evidence on the presence of room-temperature stable magnetism and a novel perspective to understand magnetic and electronic reconstructions at such strategic oxide interfaces.

  10. Eutectic Gallium-Indium (EGaIn) : A Liquid Metal Alloy for the Formation of Stable Structures in Microchannels at Room Temperature

    NARCIS (Netherlands)

    Dickey, Michael D.; Chiechi, Ryan C.; Larsen, Ryan J.; Weiss, Emily A.; Weitz, David A.; Whitesides, George M.

    2008-01-01

    This paper describes the rheological behavior of the liquid metal eutectic gallium-indium (EGaIn) as it is injected into microfluidic channels to form stable microstructures of liquid metal. EGaIn is well-suited for this application because of its rheological properties at room temperature: it

  11. Room temperature stable carbetocin for the prevention of postpartum haemorrhage during the third stage of labour in women delivering vaginally: study protocol for a randomized controlled trial.

    Science.gov (United States)

    Widmer, Mariana; Piaggio, Gilda; Abdel-Aleem, Hany; Carroli, Guillermo; Chong, Yap-Seng; Coomarasamy, Arri; Fawole, Bukola; Goudar, Shivaprasad; Hofmeyr, G Justus; Lumbiganon, Pisake; Mugerwa, Kidza; Nguyen, Thi My Huong; Qureshi, Zahida; Souza, Joao Paulo; Gülmezoglu, A Metin

    2016-03-17

    Postpartum haemorrhage (PPH) is the leading cause of maternal mortality in low-income countries and contributes to nearly a quarter of maternal deaths globally. The current available interventions for prevention of postpartum haemorrhage, oxytocin and carbetocin, are limited by their need for refrigeration to maintain potency, as the ability to maintain a cold chain across the drug distribution and storage network is inconsistent, thus restricting their use in countries with the highest burden of maternal mortality. We describe a randomized, double-blind non-inferiority trial comparing a newly developed room temperature stable formulation of carbetocin to the standard intervention (oxytocin) for the prevention of PPH after vaginal birth. Approximately 30,000 women delivering vaginally will be recruited across 22 centres in 10 countries. The primary objectives are to evaluate the non-inferiority of room temperature stable carbetocin (100 μg intramuscular) versus oxytocin (10 IU intramuscular) in the prevention of PPH and severe PPH after vaginal birth. The primary endpoints are blood loss ≥500 mL or the use of additional uterotonics (composite endpoint required by drug regulatory authorities) and blood loss ≥1,000 mL (WHO requirement). Non-inferiority will be assessed using a two-sided 95 % confidence interval for the relative risk of the above endpoints for room temperature stable carbetocin versus oxytocin. The upper limit of the two-sided 95 % confidence interval for the relative risk for the composite endpoint of blood loss ≥500 mL or the use of additional uterotonics, and for the endpoint of blood loss ≥1,000 mL, will be compared to a non-inferiority margin of 1.16 and 1.23, respectively. If the upper limit is below the corresponding margin, non-inferiority will have been demonstrated. The safety analysis will include all women receiving treatment. Safety and tolerability will be assessed by a review of adverse events, by conducting inferential testing

  12. Improved immunogenicity of individual influenza vaccine components delivered with a novel dissolving microneedle patch stable at room temperature.

    Science.gov (United States)

    Vassilieva, Elena V; Kalluri, Haripriya; McAllister, Devin; Taherbhai, Misha T; Esser, E Stein; Pewin, Winston P; Pulit-Penaloza, Joanna A; Prausnitz, Mark R; Compans, Richard W; Skountzou, Ioanna

    2015-08-01

    Prevention of seasonal influenza epidemics and pandemics relies on widespread vaccination coverage to induce protective immunity. In addition to a good antigenic match with the circulating viruses, the effectiveness of individual strains represented in the trivalent vaccines depends on their immunogenicity. In this study, we evaluated the immunogenicity of H1N1, H3N2, and B seasonal influenza virus vaccine strains delivered individually with a novel dissolving microneedle patch and the stability of this formulation during storage at 25 °C. Our data demonstrate that all strains retained their antigenic activity after incorporation in the dissolving patches as measured by single radial diffusion (SRID) assay and immune responses to vaccination in BALB/c mice. After a single immunization, all three antigens delivered with microneedle patches induced superior neutralizing antibody titers compared to intramuscular immunization. Cutaneous antigen delivery was especially beneficial for the less immunogenic B strain. Mice immunized with dissolving microneedle patches encapsulating influenza A/Brisbane/59/07 (H1N1) vaccine were fully protected against lethal challenge by homologous mouse-adapted influenza virus. All vaccine components retained activity during storage at room temperature for at least 3 months as measured in vitro by SRID assay and in vivo by mouse immunization studies. Our data demonstrate that dissolving microneedle patches are a promising advance for influenza cutaneous vaccination due to improved immune responses using less immunogenic influenza antigens and enhanced stability.

  13. Improved immunogenicity of individual influenza vaccine components delivered with a novel dissolving microneedle patch stable at room temperature

    Science.gov (United States)

    Vassilieva, Elena V.; Kalluri, Haripriya; McAllister, Devin; Taherbhai, Misha T.; Esser, E. Stein; Pewin, Winston P.; Pulit-Penaloza, Joanna A.; Prausnitz, Mark R.; Compans, Richard W.; Skountzou, Ioanna

    2015-01-01

    Prevention of seasonal influenza epidemics and pandemics relies on widespread vaccination coverage to induce protective immunity. In addition to a good antigenic match with the circulating viruses, the effectiveness of individual strains represented in the trivalent vaccines depends on their immunogenicity. In this study we evaluated the immunogenicity of H1N1, H3N2 and B seasonal influenza virus vaccine strains delivered individually with a novel dissolving microneedle patch and the stability of this formulation during storage at 25°C. Our data demonstrate that all strains retained their antigenic activity after incorporation in the dissolving patches as measured by SRID assay and immune responses to vaccination in BALB/c mice. After a single immunization all three antigens delivered with microneedle patches induced superior neutralizing antibody titers compared to intramuscular immunization. Cutaneous antigen delivery was especially beneficial for the less immunogenic B strain. Mice immunized with dissolving microneedle patches encapsulating influenza A/Brisbane/59/07 (H1N1) vaccine were fully protected against lethal challenge by homologous mouse-adapted influenza virus. All vaccine components retained activity during storage at room temperature for at least three months as measured in vitro by SRID assay and in vivo by mouse immunization studies. Our data demonstrate that dissolving microneedle patches are a promising advance for influenza cutaneous vaccination due to improved immune responses using less immunogenic influenza antigens and enhanced stability. PMID:25895053

  14. Room Temperature Curing Polymers

    Science.gov (United States)

    1977-05-01

    UJ LU LU LU UJ LU W -Q U "O 26 -- - -■- — ■ ■- ■ MBti ^L. IIIIIIII.IHI.I|.UHI,IW’I»;I.!I"IT,U» mpwi«ŕ "^Wl be 190,000 psi which is consistent...was added to the mixture. After 1 hour benzene and water were added and the mixture was stirred until the salt was dissolved. The organic ...for 15 minutes and then cooled to room temperature. The mixture was extracted with two 100 ml portions of water. The organic layer was dried (MgS04

  15. Room temperature ferromagnetic and photoluminescence ...

    Indian Academy of Sciences (India)

    32

    electrode, photo electronic devices, photo sensors, liquid crystal displays, electrochromic windows, solar panels and transparent coatings for solar-energy heat mirrors [11-13]. Here we report on magnetic properties of ITO nanoparticles at room temperature and at 100 K. 2. Experimental. The In1.9Sn0.1O3 powder samples ...

  16. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-06-01

    Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous

  17. Room temperature cryogenic test interface

    International Nuclear Information System (INIS)

    Faris, S. M.; Davidson, A.; Moskowitz, P. A.; Sai-Halasz, G. A.

    1985-01-01

    This interface permits the testing of high speed semiconductor devices (room-temperature chips) by a Josephson junction sampling device (cryogenic chip) without intolerable loss of resolution. The interface comprises a quartz pass-through plug which includes a planar transmission line interconnecting a first chip station, where the cryogenic chip is mounted, and a second chip station, where the semiconductor chip to be tested is temporarily mounted. The pass-through plug has a cemented long half-cylindrical portion and short half-cylindrical portion. The long portion carries the planar transmission line, the ends of which form the first and second chip mounting stations. The short portion completes the cylinder with the long portion for part of its length, where a seal can be achieved, but does not extend over the chip mounting stations. Sealing is by epoxy cement. The pass-through plug is sealed in place in a flange mounted to the chamber wall. The first chip station, with the cryogenic chip attached, extends into the liquid helium reservoir. The second chip station is in the room temperature environment required for semiconductor operation. Proper semiconductor operating temperature is achieved by a heater wire and control thermocouple in the vicinity of each other and the second chip mounting station. Thermal isolation is maintained by vacuum and seals. Connections for power and control, for test result signals, for temperature control and heating, and for vacuum complete the test apparatus

  18. Near room temperature approaches for the preparation of air-stable and crystalline CH{sub 3}NH{sub 3}PbI{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Gujarathi, Yogini D.; Haram, Santosh K., E-mail: haram@chem.unipune.ac.in

    2016-04-15

    This work demonstrates an exotic role of CH{sub 2}Cl{sub 2} in a formation of stable phase of highly crystalline CH{sub 3}NH{sub 3}PbI{sub 3} perovskite, on a bulk scale. In the first method, a partially-reacted product obtained after co-grinding of precursors viz. CH{sub 3}NH{sub 3}I and PbI{sub 2}was sonicated in CH{sub 2}Cl{sub 2} to form pure phase of CH{sub 3}NH{sub 3}PbI{sub 3}. In second method, the precursors in γ-Butyrolactone were treated with CH{sub 2}Cl{sub 2} to form crystalline and phase-pure CH{sub 3}NH{sub 3}PbI{sub 3}. X-ray Diffraction analysis confirmed the formation of stable and highly crystalline tetragonal phase of CH{sub 3}NH{sub 3}PbI{sub 3} perovskite having space group I4cm. Well-defined rhombo-hexagonal dodecahedron crystals were seen in SEM and TEM images. Exceptional air stability of CH{sub 3}NH{sub 3}PbI{sub 3} so forms are attributed to adsorption of CH{sub 2}Cl{sub 2}. Optical band gaps obtained from the diffused reflectance spectra (Kubelka–Munk analysis), matched very well with the one estimated from Cyclic Voltammetry (CV). Valence band and conduction band edge positions estimated from the CV analysis are in good agreement with the one reported from UV photoelectron spectroscopy. Both the samples gave steady state fluorescence at ca. 750 nm with quantum yields in the range 15–35.5%. - Highlights: • A role of CH{sub 2}Cl{sub 2} is brought out in formation of stable CH{sub 3}NH{sub 3}PbI{sub 3} perovskite. • Cyclic voltammetry has been used to estimate the band edge positions. • Excellent fluorescence quantum yield, underlines the minimal structural defects.

  19. Highly oriented δ-Bi2O3 thin films stable at room temperature synthesized by reactive magnetron sputtering

    DEFF Research Database (Denmark)

    Lunca Popa, P.; Sønderby, S.; Kerdsongpanya, S.

    2013-01-01

    We report the synthesis by reactive magnetron sputtering and structural characterization of highly (111)-oriented thin films of δ–Bi2O3. This phase is obtained at a substrate temperature of 150–200 °C in a narrow window of O2/Ar ratio in the sputtering gas (18%–20%). Transmission electron...

  20. 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.

  1. Room temperature water Leidenfrost droplets.

    Science.gov (United States)

    Celestini, Franck; Frisch, Thomas; Pomeau, Yves

    2013-10-28

    We experimentally investigate the Leidenfrost effect at pressures ranging from 1 to 0.05 atmospheric pressure. As a direct consequence of the Clausius–Clapeyron phase diagram of water, the droplet temperature can be at ambient temperature in a non-sophisticated lab environment. Furthermore, the lifetime of the Leidenfrost droplet is significantly increased in this low pressure environment. The temperature and pressure dependence of the evaporation rate is successfully tested against a recently proposed model. These results may pave the way for reaching efficient Leidenfrost micro-fluidic and milli-fluidic applications.

  2. Materials for Room Temperature Magnetic Refrigeration

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl

    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......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...

  3. 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.

  4. Mechanochemically assisted room temperature solid state ...

    Indian Academy of Sciences (India)

    Unknown

    also known to induce nucleation leading to new products. (Stojanovic et al 2005). However, solid state reactions occurring under mechanochemical influence taking place at room temperature are rare (Xian et al 1991). In this communication, we report the formation of divalent molyb- dates through mechanochemically ...

  5. Room-temperature ferromagnetic and photoluminescence ...

    Indian Academy of Sciences (India)

    ent electrodes, photoelectronic devices, photosensors, liquid crystal displays, electrochromic windows, solar panels and transparent coatings for solar-energy heat mirrors [11–13]. Here we report on magnetic properties of ITO nanoparticles at room temperature and at 100 K. 2. Experimental. In1.9Sn0.1O3 powder samples ...

  6. Room temperature synthesis of biodiesel using sulfonated ...

    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. Prepared for submission to Royal Society of Chemistry (RSC) journal, Green Chemistry as a communication.

  7. 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)

  8. Above Room Temperature Lead Salt VECSELs

    Science.gov (United States)

    Rahim, M.; Khiar, A.; Felder, F.; Fill, M.; Chappuis, D.; Zogg, H.

    2010-01-01

    Mid-infrared vertical external cavity surface emitting lasers (VECSEL) were developed for the wavelength range 4 to 5 μm. The devices are based on lead salt materials grown by MBE on BaF2 or Si substrate. The VECSELs are optically pumped with a 1.55 μm wavelength laser. They are operating up to above room temperature. An output power 6 mWp was reached at a temperature of +27°C. The VECSELs are temperature tunable and lasing is observed from ˜4.8 μm at -60°C down to ˜4.2 μm at +40°C heat sink temperature.

  9. 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.

  10. Stable single-frequency output at 2.01 microm from a diode-pumped monolithic double diffusion-bonded Tm:YAG nonplanar ring oscillator at room temperature.

    Science.gov (United States)

    Gao, Chunqing; Gao, Mingwei; Zhang, Yunshan; Lin, Zhifeng; Zhu, Lingni

    2009-10-01

    We demonstrate a monolithic double diffusion-bonded monolithic Tm:YAG nonplanar ring laser pumped by a fiber-coupled laser diode. Up to 867 mW single-frequency output at 2.01 microm was obtained from the Tm:YAG system at room temperature, with a slope efficiency and an optical-optical efficiency of 31.6% and 19.2%. The power stability of the single frequency laser was 0.32% within 30 min.

  11. Temperature and Humidity Control in Livestock Stables

    DEFF Research Database (Denmark)

    Hansen, Michael; Andersen, Palle; Nielsen, Kirsten M.

    2010-01-01

    The paper describes temperature and humidity control of a livestock stable. It is important to have a correct air flow pattern in the livestock stable in order to achieve proper temperature and humidity control as well as to avoid draught. In the investigated livestock stable the air flow...... is controlled using wall mounted ventilation flaps. In the paper an algorithm for air flow control is presented meeting the needs for temperature and humidity while taking the air flow pattern in consideration. To obtain simple and realisable controllers a model based control design method is applied....... In the design dynamic models for temperature and humidity are very important elements and effort is put into deriving and testing the models. It turns out that non-linearities are dominating in both models making feedback linearization the natural design method. The air controller as well as the temperature...

  12. 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

  13. Calculation of Vertical Temperature Gradients in Heated Rooms

    DEFF Research Database (Denmark)

    Overby, H.; Steen-Thøde, Mogens

    This paper deals with a simple model which predicts the vertical temperature gradient in a heated room. The gradient is calculated from a dimensionless temperature profile which is determined by two room air temperatures only, the mean temperature in the occupied zone and the mean temperature...... in the zone above the occupied zone. A model to calculate the two air temperatures has been developed and implemented in Suncode- PC, a thermal analysis programme for residential and small commercial buildings. The dimensionless temperature profile based on measurements in a laboratory test room is presented...

  14. Injectable sodium pentobarbital: Stability at room temperature.

    Science.gov (United States)

    Priest, Sydney M; Geisbuhler, Timothy P

    2015-01-01

    Sodium pentobarbital (Nembutal) is a barbiturate used in research as an anesthetic in many animal models. The injectable form of this drug has lately become difficult to procure and prohibitively expensive. Due to this lack of availability, researchers have begun to compound injectable sodium pentobarbital from so-called "nonpharmaceutical" pentobarbital. Some oversight agencies have objected to this practice, claiming a lack of quality control and degradation of the drug. We sought with this study to establish both: 1) a protocol for the preparation of injectable sodium pentobarbital, and 2) standard operating procedures to monitor the quality of the preparation and degradation of the drug over time. Our preparation consists of a mixture of sodium pentobarbital in alkaline aqueous solution, propylene glycol, and ethanol. Pentobarbital content in this preparation was assayed by high-pressure liquid chromatography (HPLC). We also assayed pentobarbital content over time in preparations of various ages up to 6 years old. We determined that the drug degraded at a maximum of 0.5% per year in our preparation (alkaline water/propylene glycol/ethanol) when stored in the dark at room temperature. A yellow discoloration developed after about 2 years, which we have arbitrarily determined disqualifies the preparation from use as an anesthetic. Attempts to spectroscopically assay this discoloration were not successful. Pentobarbital sodium (CID: 14075609). Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Water in Room Temperature Ionic Liquids

    Science.gov (United States)

    Fayer, Michael

    2014-03-01

    Room temperature ionic liquids (or RTILs, salts with a melting point below 25 °C) have become a subject of intense study over the last several decades. Currently, RTIL application research includes synthesis, batteries, solar cells, crystallization, drug delivery, and optics. RTILs are often composed of an inorganic anion paired with an asymmetric organic cation which contains one or more pendant alkyl chains. The asymmetry of the cation frustrates crystallization, causing the salt's melting point to drop significantly. In general, RTILs are very hygroscopic, and therefore, it is of interest to examine the influence of water on RTIL structure and dynamics. In addition, in contrast to normal aqueous salt solutions, which crystallize at low water concentration, in an RTIL it is possible to examine isolated water molecules interacting with ions but not with other water molecules. Here, optical heterodyne-detected optical Kerr effect (OHD-OKE) measurements of orientational relaxation on a series of 1-alkyl-3-methylimidazolium tetrafluoroborate RTILs as a function of chain length and water concentration are presented. The addition of water to the longer alkyl chain RTILs causes the emergence of a long time bi-exponential orientational anisotropy decay. Such decays have not been seen previously in OHD-OKE experiments on any type of liquid and are analyzed here using a wobbling-in-a-cone model. The orientational relaxation is not hydrodynamic, with the slowest relaxation component becoming slower as the viscosity decreases for the longest chain, highest water content samples. The dynamics of isolated D2O molecules in 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) were examined using two dimensional infrared (2D IR) vibrational echo spectroscopy. Spectral diffusion and incoherent and coherent transfer of excitation between the symmetric and antisymmetric modes are examined. The coherent transfer experiments are used to address the nature of inhomogeneous

  16. Structure determination at room temperature and phase transition ...

    Indian Academy of Sciences (India)

    Unknown

    Structure determination at room temperature and phase transition studies above Tc in ABi4Ti4O15 (A = Ba, Sr or Pb). G NALINI and T N GURU ROW*. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India. MS received 9 May 2002. Abstract. The room temperature structure of three ...

  17. 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...

  18. Room temperature to cryogenic electrical interface

    International Nuclear Information System (INIS)

    Faris, S.M.

    1988-01-01

    A monolithic superconductive chip is described comprising: a. a substrate with a low temperature region and a high temperature region; b. a low temperature electronic circuit formed on the low temperature region and including an element which is superconductive when it has a temperature below a critical level; and c. electrical conductors formed on the substrate, the conductors being connected to the electronic circuit and traversing the substrate to the high temperature region

  19. Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field

    KAUST Repository

    Zhang, Senfu

    2018-03-29

    Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature skyrmions in sputtered multilayer films are an important step towards their use in ultra-low power devices. Such practical applications prefer skyrmions to be stable at zero magnetic fields and room temperature. Here, we report the creation of skyrmion lattices in Pt/Co/Ta multilayers by a scanning local field using magnetic force microscopy tips. We also show that those newly created skyrmion lattices are stable at both room temperature and zero fields. Lorentz transmission electron microscopy measurements reveal that the skyrmions in our films are of Néel-type. To gain a deeper understanding of the mechanism behind the creation of a skyrmion lattice by the scanning of local fields, we perform micromagnetic simulations and find the experimental results to be in agreement with our simulation data. This study opens another avenue for the creation of skyrmion lattices in thin films.

  20. 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.

  1. Room temperature synthesis of colloidal platinum nanoparticles

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Efficient preparation of stable dispersions of platinum nanoparticles from platinous chloride. (K2PtCl4) was achieved by simultaneous addition of capping polymer material. The size of platinum nanoparti- cles was controlled by changing the ratio of concentration of capping polymer material to the concentration of.

  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. High Power Room Temperature Terahertz Local Oscillator, Phase I

    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...

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

    OpenAIRE

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

    2016-01-01

    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.

  5. 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.

  6. Neutron absorbing room temperature vulcanizable silicone rubber compositions

    International Nuclear Information System (INIS)

    Zoch, H.L.

    1979-01-01

    A neutron absorbing composition is described and consists of a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron compound in this application is boron carbide. 20 claims

  7. 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...... of measured data is of crucial importance. Qualitatively satisfactory results do not ensure quantitative agreement....

  8. Room temperature line lists for deuterated water

    Science.gov (United States)

    Kyuberis, Aleksandra A.; Zobov, Nikolay F.; Naumenko, Olga V.; Voronin, Boris A.; Polyansky, Oleg L.; Lodi, Lorenzo; Liu, Anwen; Hu, Shui-Ming; Tennyson, Jonathan

    2017-12-01

    Line lists are presented for six deuterated isotopologues of water vapor namely HD16O, HD17O, HD18O, D216O, D217O and D218O. These line lists are prepared using empirically-determined energy levels, where available, to provide transition frequencies and high-quality ab initio dipole moment surfaces to provide transition intensities. The reliability of the predicted intensities is tested by computing multiple line lists and analyzing the stability of the results. The resulting intensities are expected to be accurate to a few percent for well-behaved, stable transitions. Complete T = 296 K line lists are provided for each species.

  9. Efficient Room-Temperature Cooling with Magnets

    NARCIS (Netherlands)

    Boeije, M.F.J.; Roy, P.; Guillou, F.; Yibole, Hargen; Miao, X.F.; Caron, L.; Banerjee, D.; van Dijk, N.H.; de Groot, R.M.; Brück, E.H.

    2016-01-01

    Magnetic cooling is a highly efficient refrigeration technique with the potential to replace the traditional vapor compression cycle. It is based on the magnetocaloric effect, which is associated with the temperature change of a material when placed in a magnetic field. We present experimental

  10. Room-temperature ferromagnetic and photoluminescence ...

    Indian Academy of Sciences (India)

    tin oxide; solid-state reaction; ... However, when the same films are annealed in air at higher temperatures, the magnetic moment will be ... transparent coatings for solar-energy heat mirrors [11–13]. Here we report on magnetic properties of ITO ...

  11. Room-temperature synthetic pathways to barium titanate nanocrystals.

    Science.gov (United States)

    Beier, Christopher W; Cuevas, Marie A; Brutchey, Richard L

    2008-12-01

    Novel room-temperature pathways to BaTiO(3) nanocrystals have been recently developed, which stand in contrast to traditional high-temperature methods. Peptide-assisted, bio-facilitated routes have been developed for low-temperature nanocrystal growth, in addition to two low-temperature routes completely independent of biomolecules. These innovative methods lay the groundwork for the facile production of nanoscale BaTiO(3) in economical and energy-efficient ways.

  12. 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

    Magnetic skyrmions are topologically stable, vortex-like objects surrounded by chiral boundaries that separate a region of reversed magnetization from the surrounding magnetized material. They are closely related to nanoscopic chiral magnetic domain walls, which could be used as memory and logic elements for conventional and neuromorphic computing applications that go beyond Moore’s law. Of particular interest is ‘racetrack memory’, which is composed of vertical magnetic nanowires, each accommodating of the order of 100 domain walls, and that shows promise as a solid state, non-volatile memory with exceptional capacity and performance. Its performance is derived from the very high speeds (up to one kilometre per second) at which chiral domain walls can be moved with nanosecond current pulses in synthetic antiferromagnet racetracks. Because skyrmions are essentially composed of a pair of chiral domain walls closed in on themselves, but are, in principle, more stable to perturbations than the component domain walls themselves, they are attractive for use in spintronic applications, notably racetrack memory. Stabilization of skyrmions has generally been achieved in systems with broken inversion symmetry, in which the asymmetric Dzyaloshinskii-Moriya interaction modifies the uniform magnetic state to a swirling state. Depending on the crystal symmetry, two distinct types of skyrmions have been observed experimentally, namely, Bloch and Néel skyrmions. Here we present the experimental manifestation of another type of skyrmion—the magnetic antiskyrmion—in acentric tetragonal Heusler compounds with D2d crystal symmetry. Antiskyrmions are characterized by boundary walls that have alternating Bloch and Néel type as one traces around the boundary. A spiral magnetic ground-state, which propagates in the tetragonal basal plane, is transformed into an antiskyrmion lattice state under magnetic fields applied along the tetragonal axis over a wide range of temperatures

  13. Room temperature ferromagnetic gadolinium silicide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hadimani, Magundappa Ravi L.; Gupta, Shalabh; Harstad, Shane; Pecharsky, Vitalij; Jiles, David C.

    2018-03-06

    A particle usable as T1 and T2 contrast agents is provided. The particle is a gadolinium silicide (Gd5Si4) particle that is ferromagnetic at temperatures up to 290 K and is less than 2 .mu.m in diameter. An MRI contrast agent that includes a plurality of gadolinium silicide (Gd.sub.5Si.sub.4) particles that are less than 1 .mu.m in diameter is also provided. A method for creating gadolinium silicide (Gd5Si4) particles is also provided. The method includes the steps of providing a Gd5Si4 bulk alloy; grinding the Gd5Si4 bulk alloy into a powder; and milling the Gd5Si4 bulk alloy powder for a time of approximately 20 minutes or less.

  14. Concurrent transition of ferroelectric and magnetic ordering near room temperature.

    Science.gov (United States)

    Ko, Kyung-Tae; Jung, Min Hwa; He, Qing; Lee, Jin Hong; Woo, Chang Su; Chu, Kanghyun; Seidel, Jan; Jeon, Byung-Gu; Oh, Yoon Seok; Kim, Kee Hoon; Liang, Wen-I; Chen, Hsiang-Jung; Chu, Ying-Hao; Jeong, Yoon Hee; Ramesh, Ramamoorthy; Park, Jae-Hoon; Yang, Chan-Ho

    2011-11-29

    Strong spin-lattice coupling in condensed matter gives rise to intriguing physical phenomena such as colossal magnetoresistance and giant magnetoelectric effects. The phenomenological hallmark of such a strong spin-lattice coupling is the manifestation of a large anomaly in the crystal structure at the magnetic transition temperature. Here we report that the magnetic Néel temperature of the multiferroic compound BiFeO(3) is suppressed to around room temperature by heteroepitaxial misfit strain. Remarkably, the ferroelectric state undergoes a first-order transition to another ferroelectric state simultaneously with the magnetic transition temperature. Our findings provide a unique example of a concurrent magnetic and ferroelectric transition at the same temperature among proper ferroelectrics, taking a step toward room temperature magnetoelectric applications.

  15. Room Temperature Memory for Few Photon Polarization Qubits

    Science.gov (United States)

    Kupchak, Connor; Mittiga, Thomas; Jordan, Bertus; Nazami, Mehdi; Nolleke, Christian; Figueroa, Eden

    2014-05-01

    We have developed a room temperature quantum memory device based on Electromagnetically Induced Transparency capable of reliably storing and retrieving polarization qubits on the few photon level. Our system is realized in a vapor of 87Rb atoms utilizing a Λ-type energy level scheme. We create a dual-rail storage scheme mediated by an intense control field to allow storage and retrieval of any arbitrary polarization state. Upon retrieval, we employ a filtering system to sufficiently remove the strong pump field, and subject retrieved light states to polarization tomography. To date, our system has produced signal-to-noise ratios near unity with a memory fidelity of >80 % using coherent state qubits containing four photons on average. Our results thus demonstrate the feasibility of room temperature systems for the storage of single-photon-level photonic qubits. Such room temperature systems will be attractive for future long distance quantum communication schemes.

  16. Weibull strength variations between room temperature and high temperature Ni-3YSZ half-cells

    DEFF Research Database (Denmark)

    Curran, Declan; Frandsen, Henrik Lund; Hendriksen, Peter Vang

    2013-01-01

    and 800°C in a reducing atmosphere. The strength of an as sintered half-cell was also measured at room temperature for comparison. Weibull analysis was performed on large sample sets of 30 for statistical viability. The Weibull strength and elastic modulus of the room temperature tested reduced samples...... show a decrease of approximately 33% and 51% respectively, when compared to the oxidized samples tested at room temperature. When tested at elevated temperatures both Weibull strength and elastic modulus decrease further when compared to the room temperature reduced samples. However these further...... efficiency, increased degradation and/or the complete termination of a functioning stack. This paper investigates the effects of temperature on the mechanical strength of 3% yttria-stabilised zirconia half-cells. Strength was measured using a four-point bend method at room temperature and at 600°C, 700°C...

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

    Science.gov (United States)

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

    2011-07-29

    Room-temperature, easy-to-operate quantum memories are essential building blocks for future long distance quantum information networks operating on an intercontinental scale, because devices like quantum repeaters, based on quantum memories, will have to be deployed in potentially remote, inaccessible locations. Here we demonstrate controllable, broadband and efficient storage and retrieval of weak coherent light pulses at the single-photon level in warm atomic cesium vapor using the robust far off-resonant Raman memory scheme. We show that the unconditional noise floor of this technically simple quantum memory is low enough to operate in the quantum regime, even in a room-temperature environment.

  18. BF3.SiO2: an efficient catalyst for the synthesis of azo dyes at room temperature

    Directory of Open Access Journals (Sweden)

    Bi Bi Fatemeh Mirjalili

    2012-07-01

    Full Text Available A rapid one-pot method has been developed for the synthesis of azo dyes via ‎sequential diazotization–diazo coupling of aromatic amines with coupling agents at roomtemperature in the presence of BF3.SiO2 as acidic catalyst. The obtained aryl diazonium salts bearing silica supported boron tri-flouride counter ion‎ was sufficiently stable to be kept at roomtemperature in the dry state.‎

  19. 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.

  20. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 127; Issue 9. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids and their catalytic studies in multi-component Biginelli reaction. Sankaranarayanan Nagarajan Tanveer M Shaikh Elango Kandasamy. Volume 127 Issue 9 September 2015 pp 1539- ...

  1. Durability of direct immunofluorescence (DIF) slides stored at room temperature.

    Science.gov (United States)

    Elbendary, Amira; Zhou, Cheng; Truong, Jonathan; Elston, Dirk M

    2015-12-01

    Prior studies suggested that direct immunofluorescence (DIF) slides can be stored at room temperature. We sought to determine the durability of DIF slides stored at room temperature for 5 years. This was a retrospective study of 83 DIF slides archived at room temperature during 2010. The pattern of immunoreactants was compared with those noted in the original report. Loss of reactivity was limited to cases with weak fluorescence at original diagnosis. Loss of IgG was noted in 12.5% of cases, IgA in 12%, C3 in 10%, and IgM in 9.75%. Fibrin showed no loss of reactivity. Preservation of immunofluorescence was not related to site of deposition. Overall, a reliable diagnosis could be made in 75 of 79 archived cases (94.9%). Cases had been archived for periods varying from 4.5 to 5 years. Variations in processing and fluorochromes could affect durability. We have no way of knowing how long slides had been exposed to ultraviolet light at the time of initial examination. DIF showed excellent durability in slides kept at room temperature for 5 years. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

  2. Enhanced room temperature multiferroicity in Gd doped BFO

    CSIR Research Space (South Africa)

    Pradhan, SK

    2009-01-01

    Full Text Available deficient Gd doped multiferroic BFO system. At particular doping level of Gd, this bulk ceramics showed spectacular M~H behavior at room temperature which is likely to open a new avenue for the potential applications in information storing technology as well...

  3. Yttrium Nitrate mediated Nitration of Phenols at room temperature in ...

    Indian Academy of Sciences (India)

    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.

  4. A room temperature cured low dielectric hyperbranched epoxy ...

    Indian Academy of Sciences (India)

    Tomalia et al.5 Though curing kinetics of bisphenol-A based epoxy resin with 1st to 4th generations of den- dritic poly(amido-amine) with different amines were studied by DSC,6 but performance of the thermosets was not reported. Thus a detail and systematic study on curing at room temperature of a hyperbranched epoxy.

  5. Room-temperature biosynthesis of ferroelectric barium titanate nanoparticles.

    Science.gov (United States)

    Bansal, Vipul; Poddar, Pankaj; Ahmad, Absar; Sastry, Murali

    2006-09-13

    The syntheses of inorganic materials by biological systems is characterized by processes that occur close to ambient temperatures, pressures, and neutral pH, as is exemplified by biosilicification and biomineralization processes in nature. Conversely, laboratory-based syntheses of oxide materials often require extremes of temperature and pressure. We have shown here the extracellular, room-temperature biosynthesis of 4-5 nm ternary oxide nanoparticles such as barium titanate (BT) using a fungus-mediated approach. The tetragonality as well as a lowered Curie transition temperature in sub-10 nm particles was established, and the ferroelectricity in these particles was shown using Kelvin probe microscopy.

  6. Transformations of intermetallic compounds in Zr alloys at room temperature

    International Nuclear Information System (INIS)

    Filippov, V.P.; Shikanova, Yu.A.

    2004-01-01

    The formation of intermetallic compound Zr 3 Fe is shown to take place in a quaternary Zr-Fe-Sn-Cr alloy on long-term holding at room temperature. Alloys of Zr-1.0% Fe-1.27% Sn-0.51% Cr are melted in an arc furnace, quenched, hot and cold rolled. Final heat treatment is performed at 873 K for 3 h. It is assumed that the formation of intermetallic particles at low temperature is due to rearrangement of pre-precipitate structure by way of iron atom transitions at small distances. No noticeable change is found out in values of quadrupole splitting and isomer shift of Zr(Fe , Cr) 2 particles after a two-year holding at room temperature [ru

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

    Energy Technology Data Exchange (ETDEWEB)

    Elsaidi, Sameh K. [Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426 Ibrahimia Alexandria 21321 Egypt; Ongari, Daniele [Laboratory of Molecular Simulation, Institut des Sciences et Ingeénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l' Industrie 17 1951 Sion Valais Switzerland; Xu, Wenqian [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Mohamed, Mona H. [Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426 Ibrahimia Alexandria 21321 Egypt; Haranczyk, Maciej [IMDEA Materials Institute, c/Eric Kandel 2 28906 Getafe, Madrid Spain; Thallapally, Praveen K. [Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2017-07-24

    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 recycle from anesthetic gas mixture can significantly reduce its cost as anesthetic. The current technology uses series of adsorbent columns followed by low temperature distillation to recover Xe, which is expensive to use in medical facilities. Herein, we propose much efficient and simpler system to recover and recycle Xe from simulant exhale anesthetic gas mixture at room temperature using metal organic frameworks. Among the MOFs tested, PCN-12 exhibits unprecedented performance with high Xe capacity, Xe/N2 and Xe/O2 selectivity at room temperature. The in-situ synchrotron measurements suggest the Xe is occupied in 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.

  8. 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...... data a 3D finite element model has been set up to calculate the magnetic force between (graded) blocks of these materials and a permanent magnet assembly. The results have been used to calculate equilibrium points for actuation systems where the magnetic force is balanced by a spring force...

  9. Studying Room Temperature Curing of Phenolic Resin and their Composites

    Directory of Open Access Journals (Sweden)

    M.H. Beheshty

    2007-10-01

    Full Text Available Phenolic resins are synthetic low molecular weight thermoset resins which are polymerized and cured to higher molecular weights by condensation method. These resins have high weathering resistance, high oxidative thermal properties and good chemical resistance. Phenolic resins can be cured thermally or by acid curing. The most common method of curing phenolic resin is by thermal curing that takes place in the range of 130-180oC. At room temperature, however, phenolic resins are cured by acid catalysts. In this paper, room temperature curing of resol phenolic resin by para toluene sulphonic acid has been investigated. The acid quantity has been determined for room temperature curing of two types of resols to achieve a reasonable hardness and gelation time. Temperature curing and thermal stability of respective resins have been investigated by DSC and TGA, respectively. A glass-phenolic composite plate has been prepared and cured by these two methods. The results show that the optimum amount of acid is 20% by weight. Optimum mechanical properties, chemical resistance and thermal properties have been achieved for acid cured system. The hot cured resin, however, has better properties.

  10. 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.

  11. Room temperature hydrogen gas sensitivity of nanocrystalline pure tin oxide.

    Science.gov (United States)

    Shukla, S; Seal, S

    2004-01-01

    Nanocrystalline (6-8 nm) tin oxide (SnO2) thin film (100-150 nm) sensor is synthesized via sol-gel dip-coating process. The thin film is characterized using focused ion-beam microscopy (FIB) and high-resolution transmission electron microscopy (HRTEM) techniques to determine the film thickness and the nanocrystallite size. The utilization of nanocrystalline pure-SnO2 thin film to sense a typical reducing gas such as hydrogen, at room temperature, is demonstrated in this investigation. The grain growth behavior of nanocrystalline pure-SnO2 is analyzed, which shows very low activation energy (9 kJ/mol) for the grain growth within the nanocrystallite size range of 3-20 nm. This low activation energy value is correlated, via excess oxygen-ion vacancy concentration, with the room temperature hydrogen gas sensitivity of the nanocrystalline pure-SnO2 thin film sensor.

  12. 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.

  13. Digital autoradiography using room temperature CCD and CMOS imaging technology

    International Nuclear Information System (INIS)

    Cabello, Jorge; Bailey, Alexis; Kitchen, Ian; Prydderch, Mark; Clark, Andy; Turchetta, Renato; Wells, Kevin

    2007-01-01

    CCD (charged coupled device) and CMOS imaging technologies can be applied to thin tissue autoradiography as potential imaging alternatives to using conventional film. In this work, we compare two particular devices: a CCD operating in slow scan mode and a CMOS-based active pixel sensor, operating at near video rates. Both imaging sensors have been operated at room temperature using direct irradiation with images produced from calibrated microscales and radiolabelled tissue samples. We also compare these digital image sensor technologies with the use of conventional film. We show comparative results obtained with 14 C calibrated microscales and 35 S radiolabelled tissue sections. We also present the first results of 3 H images produced under direct irradiation of a CCD sensor operating at room temperature. Compared to film, silicon-based imaging technologies exhibit enhanced sensitivity, dynamic range and linearity

  14. Room temperature electrodeposition of actinides from ionic solutions

    Science.gov (United States)

    Hatchett, David W.; Czerwinski, Kenneth R.; Droessler, Janelle; Kinyanjui, John

    2017-04-25

    Uranic and transuranic metals and metal oxides are first dissolved in ozone compositions. The resulting solution in ozone can be further dissolved in ionic liquids to form a second solution. The metals in the second solution are then electrochemically deposited from the second solutions as room temperature ionic liquid (RTIL), tri-methyl-n-butyl ammonium n-bis(trifluoromethansulfonylimide) [Me.sub.3N.sup.nBu][TFSI] providing an alternative non-aqueous system for the extraction and reclamation of actinides from reprocessed fuel materials. Deposition of U metal is achieved using TFSI complexes of U(III) and U(IV) containing the anion common to the RTIL. TFSI complexes of uranium were produced to ensure solubility of the species in the ionic liquid. The methods provide a first measure of the thermodynamic properties of U metal deposition using Uranium complexes with different oxidation states from RTIL solution at room temperature.

  15. 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.

  16. Room temperature Sieving of Hydrogen Isotopes Using 2-D Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hitchcock, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Colon-Mercado, H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Krentz, T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Serkiz, S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Velten, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Xiao, S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-28

    Hydrogen isotope separation is critical to the DOE’s mission in environmental remediation and nuclear nonproliferation. Isotope separation is also a critical technology for the NNSA, and the ability to perform the separations at room temperature with a relatively small amount of power and space would be a major advancement for their respective missions. Recent work has shown that 2-D materials such as graphene and hexagonal boron nitride can act as an isotopic sieve at room temperature; efficiently separating hydrogen isotopes in water with reported separation ratios of 10:1 for hydrogen: deuterium separation for a single pass. The work performed here suggests that this technique has merit, and furthermore, we are investigating optimization and scale up of the required 2-D material based membranes.

  17. Room temperature excitation spectroscopy of single quantum dots

    Directory of Open Access Journals (Sweden)

    Christian Blum

    2011-08-01

    Full Text Available We report a single molecule detection scheme to investigate excitation spectra of single emitters at room temperature. We demonstrate the potential of single emitter photoluminescence excitation spectroscopy by recording excitation spectra of single CdSe nanocrystals over a wide spectral range of 100 nm. The spectra exhibit emission intermittency, characteristic of single emitters. We observe large variations in the spectra close to the band edge, which represent the individual heterogeneity of the observed quantum dots. We also find specific excitation wavelengths for which the single quantum dots analyzed show an increased propensity for a transition to a long-lived dark state. We expect that the additional capability of recording excitation spectra at room temperature from single emitters will enable insights into the photophysics of emitters that so far have remained inaccessible.

  18. Experimental observation of negative capacitance in ferroelectrics at room temperature.

    Science.gov (United States)

    Appleby, Daniel J R; Ponon, Nikhil K; Kwa, Kelvin S K; Zou, Bin; Petrov, Peter K; Wang, Tianle; Alford, Neil M; O'Neill, Anthony

    2014-07-09

    Effective negative capacitance has been postulated in ferroelectrics because there is a hysteresis in plots of polarization-electric field. Compelling experimental evidence of effective negative capacitance is presented here at room temperature in engineered devices, where it is stabilized by the presence of a paraelectric material. In future integrated circuits, the incorporation of such negative capacitance into MOSFET gate stacks would reduce the subthreshold slope, enabling low power operation and reduced self-heating.

  19. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids ...

    Indian Academy of Sciences (India)

    Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids and their catalytic studies in multi-component Biginelli ... ods involved use of a number of metal salts, such as Li,6 Fe,7–10 Cu,11,12 Ce,13 Zr,14 In,16 Bi,17 Yb, ..... in moderate yield, which might be due to poor solubility of starting materials. After extensive ...

  20. Room Temperature Superconductivity Revolution: Foreshadowed by Victorians, Enabled by Millenials

    OpenAIRE

    Pickett, Warren E.

    2017-01-01

    Room temperature superconductivity has been the most prominent, highly ambitious, but still imaginable, acme of materials physics for half a century. The struggle toward this revolution was foreshadowed by a Victorian novelist and championed,unsuccessfully, by dogged physicists in the 1960s to 1980s who had a workable theory but uncompliant materials. Discovery of superconductivity of H$_3$S at 200 K in the 160-200 GPa pressure range has renewed anticipation of yet higher values of the critic...

  1. 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.

  2. Adaptive Beam Loading Compensation in Room Temperature Bunching Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Chase, B. E. [Fermilab; Cullerton, E. [Fermilab; Varghese, P. [Fermilab

    2017-10-01

    In this paper we present the design, simulation, and proof of principle results of an optimization based adaptive feedforward algorithm for beam-loading compensation in a high impedance room temperature cavity. We begin with an overview of prior developments in beam loading compensation. Then we discuss different techniques for adaptive beam loading compensation and why the use of Newton?s Method is of interest for this application. This is followed by simulation and initial experimental results of this method.

  3. Continuous-wave room-temperature diamond maser

    Science.gov (United States)

    Breeze, Jonathan D.; Salvadori, Enrico; Sathian, Juna; Alford, Neil Mcn.; Kay, Christopher W. M.

    2018-03-01

    The maser—the microwave progenitor of the optical laser—has been confined to relative obscurity owing to its reliance on cryogenic refrigeration and high-vacuum systems. Despite this, it has found application in deep-space communications and radio astronomy owing to its unparalleled performance as a low-noise amplifier and oscillator. The recent demonstration of a room-temperature solid-state maser that utilizes polarized electron populations within the triplet states of photo-excited pentacene molecules in a p-terphenyl host paves the way for a new class of maser. However, p-terphenyl has poor thermal and mechanical properties, and the decay rates of the triplet sublevel of pentacene mean that only pulsed maser operation has been observed in this system. Alternative materials are therefore required to achieve continuous emission: inorganic materials that contain spin defects, such as diamond and silicon carbide, have been proposed. Here we report a continuous-wave room-temperature maser oscillator using optically pumped nitrogen–vacancy defect centres in diamond. This demonstration highlights the potential of room-temperature solid-state masers for use in a new generation of microwave devices that could find application in medicine, security, sensing and quantum technologies.

  4. Outrunning free radicals in room-temperature macromolecular crystallography

    International Nuclear Information System (INIS)

    Owen, Robin L.; Axford, Danny; Nettleship, Joanne E.; Owens, Raymond J.; Robinson, James I.; Morgan, Ann W.; Doré, Andrew S.; Lebon, Guillaume; Tate, Christopher G.; Fry, Elizabeth E.; Ren, Jingshan; Stuart, David I.; Evans, Gwyndaf

    2012-01-01

    A systematic increase in lifetime is observed in room-temperature protein and virus crystals through the use of reduced exposure times and a fast detector. A significant increase in the lifetime of room-temperature macromolecular crystals is reported through the use of a high-brilliance X-ray beam, reduced exposure times and a fast-readout detector. This is attributed to the ability to collect diffraction data before hydroxyl radicals can propagate through the crystal, fatally disrupting the lattice. Hydroxyl radicals are shown to be trapped in amorphous solutions at 100 K. The trend in crystal lifetime was observed in crystals of a soluble protein (immunoglobulin γ Fc receptor IIIa), a virus (bovine enterovirus serotype 2) and a membrane protein (human A 2A adenosine G-protein coupled receptor). The observation of a similar effect in all three systems provides clear evidence for a common optimal strategy for room-temperature data collection and will inform the design of future synchrotron beamlines and detectors for macromolecular crystallography

  5. Outrunning free radicals in room-temperature macromolecular crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Robin L., E-mail: robin.owen@diamond.ac.uk; Axford, Danny [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Nettleship, Joanne E.; Owens, Raymond J. [Rutherford Appleton Laboratory, Didcot OX11 0FA (United Kingdom); The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Robinson, James I.; Morgan, Ann W. [University of Leeds, Leeds LS9 7FT (United Kingdom); Doré, Andrew S. [Heptares Therapeutics Ltd, BioPark, Welwyn Garden City AL7 3AX (United Kingdom); Lebon, Guillaume; Tate, Christopher G. [MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH (United Kingdom); Fry, Elizabeth E.; Ren, Jingshan [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); 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)

    2012-06-15

    A systematic increase in lifetime is observed in room-temperature protein and virus crystals through the use of reduced exposure times and a fast detector. A significant increase in the lifetime of room-temperature macromolecular crystals is reported through the use of a high-brilliance X-ray beam, reduced exposure times and a fast-readout detector. This is attributed to the ability to collect diffraction data before hydroxyl radicals can propagate through the crystal, fatally disrupting the lattice. Hydroxyl radicals are shown to be trapped in amorphous solutions at 100 K. The trend in crystal lifetime was observed in crystals of a soluble protein (immunoglobulin γ Fc receptor IIIa), a virus (bovine enterovirus serotype 2) and a membrane protein (human A{sub 2A} adenosine G-protein coupled receptor). The observation of a similar effect in all three systems provides clear evidence for a common optimal strategy for room-temperature data collection and will inform the design of future synchrotron beamlines and detectors for macromolecular crystallography.

  6. 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.

  7. 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 report on a new method to cleave polymer optical fibre. The most common way to cut a polymer optical fibre is chopping it with a razor blade; however, in this approach both the fibre and the blade must be preheated in order to turn the material ductile, and thus, prevent crazing....... 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...

  8. 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.

  9. Room-temperature atmospheric pressure plasma plume for biomedical applications

    International Nuclear Information System (INIS)

    Laroussi, M.; Lu, X.

    2005-01-01

    As low-temperature nonequilibrium plasmas come to play an increasing role in biomedical applications, reliable and user-friendly sources need to be developed. These plasma sources have to meet stringent requirements such as low temperature (at or near room temperature), no risk of arcing, operation at atmospheric pressure, preferably hand-held operation, low concentration of ozone generation, etc. In this letter, we present a device that meets exactly such requirements. This device is capable of generating a cold plasma plume several centimeters in length. It exhibits low power requirements as shown by its current-voltage characteristics. Using helium as a carrier gas, very little ozone is generated and the gas temperature, as measured by emission spectroscopy, remains at room temperature even after hours of operations. The plasma plume can be touched by bare hands and can be directed manually by a user to come in contact with delicate objects and materials including skin and dental gum without causing any heating or painful sensation

  10. 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.

  11. In vitro comparison of output fluid temperatures for room temperature and prewarmed fluids.

    Science.gov (United States)

    Soto, N; Towle Millard, H A; Lee, R A; Weng, H Y

    2014-08-01

    To determine if prewarmed intravenous fluids produce superior fluid output temperatures compared with room temperature fluids at common anaesthetic fluid rates for small animal patients. A prospective, randomised, in vitro fluid line test-vein study was performed. Nine flow rates were analysed (10, 20, 60, 100, 140, 180, 220, 260 and 300 mL/hour) for room temperature fluids (21°C) and for five prewarmed fluids (40, 45, 50, 55 and 60°C). For each flow rate tested, room temperature fluids never exceeded 25°C at any time point for each trial (range 18 to 25°C). For each flow rate tested, prewarmed fluids never exceeded 25 · 5°C at any time point for each trial (range 18 to 25 · 5°C). The mean output fluid temperature of prewarmed fluids was significantly warmer than room temperature fluids only at 300 mL/hour for 40°C (P = 0 · 0012), 45°C (P = 0 · 004), 50°C (P = 0 · 0002), 55°C (P = 0 · 0001) and 60°C (P fluids (up to 60°C) compared with room temperature intravenous fluids at common anaesthetic fluid rates for small animals. © 2014 British Small Animal Veterinary Association.

  12. Room temperature electrodeposition of aluminum antimonide compound semiconductor

    International Nuclear Information System (INIS)

    Gandhi, T.; Raja, K.S.; Misra, M.

    2008-01-01

    AlSb is a group III-V compound semiconductor material that is conventionally grown by high temperature processes such as Czochralski and Bridgman methods. Development of a method to synthesize AlSb at room temperature will be more economical to help modulate the electronic properties. In this investigation, a pulsed potential electrodeposition method using a room temperature molten salt system (aluminum trichloride, AlCl 3 /1-methyl-3-ethylimidazolium chloride, EMIC) with an addition of SbCl 3 is discussed. The potential pulse parameters were established by carrying out cyclic voltammetry at different concentrations of SbCl 3 and with varying molar ratios of AlCl 3 /EMIC. Stoichiometric AlSb deposits were obtained from an acidic AlCl 3 /EMIC (1.5:1 molar ratio) melt containing 4 x 10 -3 mol/l of SbCl 3 onto an ordered TiO 2 nanotubular template. The AlSb compound was predominantly amorphous in as-deposited condition and annealing at 350 deg. C for 2 h in argon transformed into crystalline phase. The AlSb deposit showed a high resistivity in the order of 10 9 Ω-cm and a defect concentration of 10 16 cm -3 which was attributed to presence of carbon. The deposits obtained from a basic melt (0.67:1 molar ratio of AlCl 3 /EMIC) were enriched with antimony

  13. Giant room temperature magnetoelectric response in strain controlled nanocomposites

    Science.gov (United States)

    Rafique, Mohsin; Herklotz, Andreas; Dörr, Kathrin; Manzoor, Sadia

    2017-05-01

    We report giant magnetoelectric coupling at room temperature in a self-assembled nanocomposite of BiFeO3-CoFe2O4 (BFO-CFO) grown on a BaTiO3 (BTO) crystal. The nanocomposite consisting of CFO nanopillars embedded in a BFO matrix exhibits weak perpendicular magnetic anisotropy due to a small out-of-plane compression (˜0.3%) of the magnetostrictive (CFO) phase, enabling magnetization rotation under moderate in-plane compression. Temperature dependent magnetization measurements demonstrate strong magnetoelastic coupling between the BaTiO3 substrate and the nanocomposite film, which has been exploited to produce a large magnetoelectric response in the sample. The reorientation of ferroelectric domains in the BTO crystal upon the application of an electric field (E) alters the strain state of the nanocomposite film, thus enabling control of its magnetic anisotropy. The strain mediated magnetoelectric coupling coefficient α = μ o d M / d E calculated from remnant magnetization at room temperature is 2.6 × 10-7 s m-1 and 1.5 × 10-7 s m-1 for the out-of-plane and in-plane orientations, respectively.

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

    Energy Technology Data Exchange (ETDEWEB)

    Elsaidi, Sameh K. [Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA; Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426 Ibrahimia Alexandria 21321 Egypt; Ongari, Daniele [Laboratory of Molecular Simulation, Institut des Sciences et Ingeénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l' Industrie 17 1951 Sion Valais Switzerland; Xu, Wenqian [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Mohamed, Mona H. [Chemistry Department, Faculty of Science, Alexandria University, P. O. Box 426 Ibrahimia Alexandria 21321 Egypt; Haranczyk, Maciej [IMDEA Materials Institute, c/Eric Kandel 2 28906 Getafe, Madrid Spain; Thallapally, Praveen K. [Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA

    2017-07-24

    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 recycle from anesthetic gas mixture can significantly reduce its cost as anesthetic. The current technology uses series of adsorbent columns followed by low temperature distillation to recover Xe, which is expensive to use in medical facilities. Herein, we propose much efficient and simpler system to recover and recycle Xe from simulant exhale anesthetic gas mixture at room temperature using metal organic frameworks. Among the MOFs tested, PCN-12 exhibits unprecedented performance with high Xe capacity, Xe/O2, Xe/N2 and Xe/CO2 selectivity at room temperature. The in-situ synchrotron measurements suggest the Xe is occupied in 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.

  15. Magnetic refrigeration--towards room-temperature applications

    International Nuclear Information System (INIS)

    Brueck, E.; Tegus, O.; Li, X.W.; Boer, F.R. de; Buschow, K.H.J.

    2003-01-01

    Modern society relies very much on readily available cooling. Magnetic refrigeration based on the magneto-caloric effect (MCE) has become a promising competitive technology for the conventional gas-compression/expansion technique in use today. Recently, there have been two breakthroughs in magnetic-refrigeration research: one is that American scientists demonstrated the world's first room-temperature, permanent-magnet, magnetic refrigerator; the other one is that we discovered a new class of magnetic refrigerant materials for room-temperature applications. The new materials are manganese-iron-phosphorus-arsenic (MnFe(P,As)) compounds. This new material has important advantages over existing magnetic coolants: it exhibits a huge MCE, which is larger than that of Gd metal; and its operating temperature can be tuned from about 150 to about 335 K by adjusting the P/As ratio. Here we report on further improvement of the materials by increasing the Mn content. The large entropy change is attributed to a field-induced first-order phase transition enhancing the effect of the applied magnetic field. Addition of Mn reduces the thermal hysteresis, which is intrinsic to the first-order transition. This implies that already moderate applied magnetic fields of below 2 T may suffice

  16. Stability of Sodium Electrodeposited From a Series of Room Temperature Chloroaluminate Molten Salts

    National Research Council Canada - National Science Library

    Gray, Gary

    1996-01-01

    .... This work&involved the synthesis of room temperature molten salts and the examination of the electrochemical and transport properties of these salts with the goal of developing a room temperature molten salt...

  17. Micro-alloyed wrought magnesium for room-temperature forming

    Energy Technology Data Exchange (ETDEWEB)

    Riemelmoser, F.O.; Kuehlein, M.; Kilian, H.; Kettner, M. [ARC Leichtmetallkompetenzzentrum Ranshofen GmbH, Postfach 26, 5282 Ranshofen (Austria); Haenzi, A.C.; Uggowitzer, P.J. [Laboratory of Metal Physics und Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland)

    2007-09-15

    In this work the development of a system of micro-alloyed Mg-Ag-Ca-Mn-(Zr) alloys is described. It involves grain refinement throughout the production chain of direct chill casting and extrusion. After extrusion the alloys reveal a homogeneous microstructure and a fine grain size of less than 10 {mu}m. At room temperature they show an exceptionally high elongation to fracture - of more than 25 % - and a pronounced work hardening regime. Superplastic behaviour is observed at 360 C. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  18. 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...

  19. Synthesize of Superparamagnetic Zinc Ferrite Nanoparticles at Room Temperature

    Directory of Open Access Journals (Sweden)

    R. Raeisi Shahraki

    2012-12-01

    Full Text Available Superparamagnetic single phase zinc ferrite nanoparticles have been prepared by coprecipitation method at 20 °C without any subsequent calcination. The composition, crystallite size, microstructure and magnetic properties of the prepared nanoparticles were investigated using X-ray diffraction (XRD, field emission scanning electron microscope (FESEM, transmission electron microscope (TEM, Fourier transmission infrared spectrum (FTIR and vibrating sample magnetometer (VSM. The XRD pattern proved that the nanoparticles were single phase cubic spinel ZnFe2O4 with crystallite size of 5nm. The magnetic measurement showed that the as-prepared nanoparticles of zinc ferrite were superparamagnet at room temperature.

  20. Room temperature deposition of magnetite thin films on organic substrate

    International Nuclear Information System (INIS)

    Arisi, E.; Bergenti, I.; Cavallini, M.; Murgia, M.; Riminucci, A.; Ruani, G.; Dediu, V.

    2007-01-01

    We report on the growth of magnetite films directly on thin layers of organic semiconductors by means of an electron beam ablation method. The deposition was performed at room temperature in a reactive plasma atmosphere. Thin films show ferromagnetic (FM) hysteresis loops and coercive fields of hundreds of Oersted. Micro Raman analysis indicates no presence of spurious phases. The morphology of the magnetite film is strongly influenced by the morphology of the underlayer of the organic semiconductor. These results open the way for the application of magnetite thin films in the field of organic spintronics

  1. Hydrogen-induced room-temperature plasticity in TC4 and TC21 alloys

    DEFF Research Database (Denmark)

    Yuan, Baoguo; Jin, Yongyue; Hong, Chuanshi

    2017-01-01

    In order to reveal the effect of hydrogen on the room-temperature plasticity of the titanium alloys TC4 and TC21, compression tests have been carried out at room temperature. Results show that an appropriate amount of hydrogen can improve the room-temperature plasticity of both the TC4 and TC21 a...

  2. Thermal power generation during heat cycle near room temperature

    Science.gov (United States)

    Shibata, Takayuki; Fukuzumi, Yuya; Kobayashi, Wataru; Moritomo, Yutaka

    2018-01-01

    We demonstrate that a sodium-ion secondary battery (SIB)-type thermocell consisting of two types of Prussian blue analogue (PBA) with different electrochemical thermoelectric coefficients (S EC ≡ ∂V/∂T V and T are the redox potential and temperature, respectively) produces electrical energy during heat cycles. The device produces an electrical energy of 2.3 meV/PBA per heat cycle between 295 K (= T L) and 323 K (= T H). The ideal thermal efficiency (η = 1.0%), which is evaluated using the heat capacity (C = 4.16 meV/K) of ideal Na2Co[Fe(CN)6], reaches 11% of the Carnot efficiency (ηth = 8.7%). Our SIB-type thermocell is a promising thermoelectric device that harvests waste heat near room temperature.

  3. Room-Temperature Ferrimagnet with Frustrated Antiferroelectricity: Promising Candidate Toward Multiple-State Memory

    Directory of Open Access Journals (Sweden)

    P. S. Wang

    2014-03-01

    Full Text Available On the basis of first-principles calculations, we show that the M-type hexaferrite BaFe_{12}O_{19} exhibits frustrated antiferroelectricity associated with its trigonal bipyramidal Fe^{3+} sites. The ferroelectric state of BaFe_{12}O_{19}, reachable by applying an external electric field to the antiferroelectric state, can be made stable at room temperature by appropriate element substitution or strain engineering. Thus, M-type hexaferrite, as a new type of multiferoic with coexistence of antiferroelectricity and ferrimagnetism, provides a basis for studying the phenomenon of frustrated antiferroelectricity and realizing multiple-state memory devices.

  4. Primary standard of optical power operating at room temperature

    Directory of Open Access Journals (Sweden)

    Dönsberg Timo

    2014-01-01

    Full Text Available The Predictable Quantum Efficient Detector (PQED is evaluated as a new primary standard of optical power. Design and characterization results are presented for a new compact room temperature PQED that consists of two custom-made induced junction photodiodes mounted in a wedged trap configuration. The detector assembly includes a window aligned in Brewster angle in front of the photodiodes for high transmission of p polarized light. The detector can also be operated without the window, in which case a dry nitrogen flow system is utilized to prevent dust contamination of the photodiodes. Measurements of individual detectors at the wavelength of 488 nm indicate that reflectance and internal quantum efficiency are consistent within 14 ppm and 10 ppm (ppm = part per million, respectively, and agree with the predicted values. The measured photocurrent ratio of the two photodiodes confirms the predicted value for s and p polarized light, and the spatial variation in the photocurrent ratio can be used to estimate the uniformity in the thickness of the silicon dioxide layer on the surface of the photodiodes. In addition, the spatial non-uniformity of the responsivity of the PQED is an order of magnitude lower than that of single photodiodes. Such data provide evidence that the room temperature PQED may replace the cryogenic radiometer as a primary standard of optical power in the visible wavelength range.

  5. Uniaxial ratcheting behavior of Zircaloy-4 tubes at room temperature

    International Nuclear Information System (INIS)

    Wen, Mingjian; Li, Hua; Yu, Dunji; Chen, Gang; Chen, Xu

    2013-01-01

    In this study, a series of uniaxial tensile, strain cycling and uniaxial ratcheting tests were conducted at room temperature on Zircaloy-4 (Zr-4) tubes used as nuclear fuel cladding in Pressurized Water Reactors (PWRs) for the purpose to investigate the uniaxial ratcheting behavior of Zr-4 and the factors which may influence it. The experimental results show that at room temperature this material features cyclic softening remarkably within the strain range of 1.6%, and former cycling under larger strain amplitude cannot retard cyclic softening of later cycling under lower strain amplitude. Uniaxial ratcheting strain accumulates in the direction of mean stress, and the ratcheting stain level is larger under tensile mean stress than that under compressive mean stress. Uniaxial ratcheting strain level increases with the increase of mean stress and stress amplitude, and decreases with the increase of loading rate. The sequence of loading rate appears to have no effects on the final ratcheting strain accumulation. Loading history has great influence on the uniaxial ratcheting behavior. Lower stress level after loading history with higher stress level leads to the shakedown of ratcheting. Higher loading rate after loading history with lower loading rate brings down the ratcheting strain rate. Uniaxial ratcheting behavior is sensitive to compressive pre-strain, and the decay rate of the ratcheting strain rate is slowed down by pre-compression

  6. Short communication: Stability and integrity of classical swine fever virus RNA stored at room temperature

    Directory of Open Access Journals (Sweden)

    Damarys Relova

    2017-12-01

    Full Text Available Worldwide cooperation between laboratories working with classical swine fever virus (CSFV requires exchange of virus isolates. For this purpose, shipment of CSFV RNA is a safe alternative to the exchange of infectious material. New techniques using desiccation have been developed to store RNA at room temperature and are reported as effective means of preserving RNA integrity. In this study, we evaluated the stability and integrity of dried CSFV RNA stored at room temperature. First, we determined the stability of CSFV RNA covering CSFV genome regions used typically for the detection of viral RNA in diagnostic samples by reverse transcription-polymerase chain reaction (RT-PCR. To this end, different concentrations of in vitro-transcribed RNAs of the 5’-untranslated region and of the NS5B gene were stored as dried RNA at 4, 20, and 37oC for two months. Aliquots were analyzed every week by CSFV-specific quantitative real-time RT-PCR. Neither the RNA concentration nor the storage temperature did affect CSFV RNA yields at any of the time evaluated until the end of the experiment. Furthermore, it was possible to recover infectious CSFV after transfection of SK-6 cells with dried viral RNA stored at room temperature for one week. The full-length E2 of CSFV was amplified from all the recovered viruses, and nucleotide sequence analysis revealed 100% identity with the corresponding sequence obtained from RNA of the original material. These results show that CSFV RNA stored as dried RNA at room temperature is stable, maintaining its integrity for downstream analyses and applications.

  7. The Room-Temperature Chemiresistive Properties of Potassium Titanate Whiskers versus Organic Vapors

    Directory of Open Access Journals (Sweden)

    Alexey S. Varezhnikov

    2017-12-01

    Full Text Available The development of portable gas-sensing units implies a special care of their power efficiency, which is often approached by operation at room temperature. This issue primarily appeals to a choice of suitable materials whose functional properties are sensitive toward gas vapors at these conditions. While the gas sensitivity is nowadays advanced by employing the materials at nano-dimensional domain, the room temperature operation might be targeted via the application of layered solid-state electrolytes, like titanates. Here, we report gas-sensitive properties of potassium titanate whiskers, which are placed over a multielectrode chip by drop casting from suspension to yield a matrix mono-layer of varied density. The material synthesis conditions are straightforward both to get stable single-crystalline quasi-one-dimensional whiskers with a great extent of potassium replacement and to favor the increase of specific surface area of the structures. The whisker layer is found to be sensitive towards volatile organic compounds (ethanol, isopropanol, acetone in the mixture with air at room temperature. The vapor identification is obtained via processing the vector signal generated by sensor array of the multielectrode chip with the help of pattern recognition algorithms.

  8. Room temperature electrodeposition of aluminum antimonide compound semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Gandhi, T.; Raja, K.S. [Metallurgical and Materials Engineering, University of Nevada, Mail Stop 388, Reno, NV 89557 (United States); Misra, M. [Metallurgical and Materials Engineering, University of Nevada, Mail Stop 388, Reno, NV 89557 (United States)], E-mail: misra@unr.edu

    2008-10-15

    AlSb is a group III-V compound semiconductor material that is conventionally grown by high temperature processes such as Czochralski and Bridgman methods. Development of a method to synthesize AlSb at room temperature will be more economical to help modulate the electronic properties. In this investigation, a pulsed potential electrodeposition method using a room temperature molten salt system (aluminum trichloride, AlCl{sub 3}/1-methyl-3-ethylimidazolium chloride, EMIC) with an addition of SbCl{sub 3} is discussed. The potential pulse parameters were established by carrying out cyclic voltammetry at different concentrations of SbCl{sub 3} and with varying molar ratios of AlCl{sub 3}/EMIC. Stoichiometric AlSb deposits were obtained from an acidic AlCl{sub 3}/EMIC (1.5:1 molar ratio) melt containing 4 x 10{sup -3} mol/l of SbCl{sub 3} onto an ordered TiO{sub 2} nanotubular template. The AlSb compound was predominantly amorphous in as-deposited condition and annealing at 350 deg. C for 2 h in argon transformed into crystalline phase. The AlSb deposit showed a high resistivity in the order of 10{sup 9} {omega}-cm and a defect concentration of 10{sup 16} cm{sup -3} which was attributed to presence of carbon. The deposits obtained from a basic melt (0.67:1 molar ratio of AlCl{sub 3}/EMIC) were enriched with antimony.

  9. 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.

  10. Room-temperature antiferromagnetism in CuMnAs

    Energy Technology Data Exchange (ETDEWEB)

    Maca, F.; Masek, J. [Institute of Physics ASCR, v.v.i., Na Slovance 2, 182 21 Praha 8 (Czech Republic); Stelmakhovych, O. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2 (Czech Republic); Marti, X. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2 (Czech Republic); Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Praha 6 (Czech Republic); Reichlova, H. [Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Praha 6 (Czech Republic); Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2 (Czech Republic); Uhlirova, K. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2 (Czech Republic); Beran, P. [Nuclear Physics Institute ASCR, v.v.i., 250 68 Rez (Czech Republic); Wadley, P.; Novak, V. [Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Praha 6 (Czech Republic); Jungwirth, T., E-mail: jungw@fzu.cu [Institute of Physics ASCR, v.v.i., Cukrovarnicka 10, 162 53 Praha 6 (Czech Republic); School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2012-04-15

    We report on an experimental and theoretical study of CuMn-V compounds. In agreement with previous works we find low-temperature antiferromagnetism with Neel temperature of 50 K in the cubic half-Heusler CuMnSb. We demonstrate that the orthorhombic CuMnAs is a room-temperature antiferromagnet. Our results are based on X-ray diffraction, magnetization, transport, and differential thermal analysis measurements, and on density-functional theory calculations of the magnetic structure of CuMn-V compounds. In the discussion part of the paper we make a prediction, based on our density-functional theory calculations, that the electronic structure of CuMn-V compounds makes a transition from a semimetal to a semiconductor upon introducing the lighter group-V elements. - Highlights: Black-Right-Pointing-Pointer We report experimental observation of high temperature antiferromagnetism in CuMnAs. Black-Right-Pointing-Pointer The physical origin of the observation is discussed based on ab initio calculations. Black-Right-Pointing-Pointer We predict semimetal to semiconductor transition of the electronic structure of CuMn-V compounds. Black-Right-Pointing-Pointer We discuss the relevance of CuMn-V compounds for antiferromagnetic spintronics.

  11. Robust blind identification of room acoustic channels in symmetric alpha-stable distributed noise environments.

    Science.gov (United States)

    He, Hongsen; Lu, Jing; Chen, Jingdong; Qiu, Xiaojun; Benesty, Jacob

    2014-08-01

    Blind multichannel identification is generally sensitive to background noise. Although there have been some efforts in the literature devoted to improving the robustness of blind multichannel identification with respect to noise, most of those works assume that the noise is Gaussian distributed, which is often not valid in real room acoustic environments. This paper deals with the more practical scenario where the noise is not Gaussian. To improve the robustness of blind multichannel identification to non-Gaussian noise, a robust normalized multichannel frequency-domain least-mean M-estimate algorithm is developed. Unlike the traditional approaches that use the squared error as the cost function, the proposed algorithm uses an M-estimator to form the cost function, which is shown to be immune to non-Gaussian noise with a symmetric α-stable distribution. Experiments based on the identification of a single-input/multiple-output acoustic system demonstrate the robustness of the proposed algorithm.

  12. Outcome of impact disruption of iron meteorites at room temperature

    Science.gov (United States)

    Katsura, T.; Nakamura, A.; Takabe, A.; Okamoto, T.; Sangen, K.; Hasegawa, S.; Liu, X.; Mashimo, T.

    2014-07-01

    The iron meteorites and some M-class asteroids are generally understood to originate in the cores of differentiated planetesimals or in the local melt pools of primitive bodies. On these primitive bodies and planetesimals, a wide range of collisional events at different mass scales, temperatures, and impact velocities would have occurred. Iron materials have a brittle-ductile transition at a certain temperature, which depends on metallurgical factors such as grain size and purity, and on conditions such as strain-rate and confining pressure [1]. An evolutional scenario of iron meteorite parent bodies was proposed in which they formed in the terrestrial planet region, after which they were scattered into the main belt by collisions, Yarkovsky thermal forces, and resonances [2]. In this case, they may have experienced collisional evolution in the vicinity of the Earth before they were scattered into the main belt. The size distribution of iron bodies in the main belt may therefore have depended on the disruption threshold of iron bodies at temperature above the brittle-ductile transition. This paper presents the results of impact-disruption experiments of iron meteorite and steel specimens mm-cm in size as projectiles or targets conducted at room temperature using three light-gas guns and one powder gun. Our iron specimens were almost all smaller in size than their counterparts (as targets or projectiles, respectively). The fragment size distribution of iron material was different from that of rocks. In iron fragmentation, a higher percentage of the mass is concentrated in larger fragments, i.e., the mass fraction of fine fragments is much less than that of rocks shown in the Figure (left). This is probably due to the ductile nature of the iron materials at room temperature. Furthermore, the Figure (right) shows that the largest fragment mass fraction f is dependent not only on the energy density but also on the size of the specimens. In order to obtain a generalized

  13. Room temperature solid-state quantum bit with second-long memory

    Science.gov (United States)

    Kucsko, Georg; Maurer, Peter; Latta, Christian; Hunger, David; Jiang, Liang; Pastawski, Fernando; Yao, Norman; Bennet, Steven; Twitchen, Daniel; Cirac, Ignacio; Lukin, Mikhail

    2012-02-01

    Realization of stable quantum bits (qubits) that can be prepared and measured with high fidelity and that are capable of storing quantum information for long times exceeding seconds is an outstanding challenge in quantum science and engineering. Here we report on the realization of such a stable quantum bit using an individual ^13C nuclear spin within an isotopically purified diamond crystal at room temperature. Using an electronic spin associated with a nearby Nitrogen Vacancy color center, we demonstrate high fidelity initialization and readout of a single ^13C qubit. Quantum memory lifetime exceeding one second is obtained by using dissipative optical decoupling from the electronic degree of freedom and applying a sequence of radio-frequency pulses to suppress effects from the dipole-dipole interactions of the ^13C spin-bath. Techniques to further extend the quantum memory lifetime as well as the potential applications are also discussed.

  14. 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...

  15. Stretchable microelectrode array using room-temperature liquid alloy interconnects

    International Nuclear Information System (INIS)

    Wei, P; Ziaie, B; Taylor, R; Chung, C; Higgs, G; Pruitt, B L; Ding, Z; Abilez, O J

    2011-01-01

    In this paper, we present a stretchable microelectrode array for studying cell behavior under mechanical strain. The electrode array consists of gold-plated nail-head pins (250 µm tip diameter) or tungsten micro-wires (25.4 µm in diameter) inserted into a polydimethylsiloxane (PDMS) platform (25.4 × 25.4 mm 2 ). Stretchable interconnects to the outside were provided by fusible indium-alloy-filled microchannels. The alloy is liquid at room temperature, thus providing the necessary stretchability and electrical conductivity. The electrode platform can withstand strains of up to 40% and repeated (100 times) strains of up to 35% did not cause any failure in the electrodes or the PDMS substrate. We confirmed biocompatibility of short-term culture, and using the gold pin device, we demonstrated electric field pacing of adult murine heart cells. Further, using the tungsten microelectrode device, we successfully measured depolarizations of differentiated murine heart cells from embryoid body clusters

  16. Ratcheting tests on stainless steel 316 L at room temperature

    International Nuclear Information System (INIS)

    Cousseran, Pierre; Lebey, Jacques; Roche, Roland; Corbel, P.

    1980-06-01

    An experimental study on progressive distortion (tension-torsion) of simple structures (thin tubes) has been undertaken at the CEA. Results of tests performed on 316 L steel at room temperature are reported in this paper. There are chiefly: - plastic iso-deformation curves in the field of the 2 loadings applied to the specimen, i.e. the constant primary loading P (tension) and the secondary loading ΔQ (cyclic torsion at controled deformation); - indications on the evolution of torque and of torsion plastic deformation, during the cycling; - a convenient rule for evaluation of the progressive distortion is proposed. It is based on the use of an effective stress Psub(eff), which is determined from the tensile characteristics of the material, of when creep occurs, from creep curves [fr

  17. 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.

  18. Convenient Reductive Methylation of Amines with Carbonates at Room Temperature.

    Science.gov (United States)

    Li, Yuehui; Sorribes, Iván; Vicent, Cristian; Junge, Kathrin; Beller, Matthias

    2015-11-16

    Methylation of amines is a fundamental and commonly used reaction in organic synthesis. Many methods are known including various reductive methylations using formaldehyde, formic acid, or carbon dioxide in the presence of reductants. However, several of these methods suffer from limited substrate scope and chemoselectivity because of the different nucleophilicities of substrates. In this respect, the combination of carbonates and hydrosilanes is a valuable methylation source in the presence of Pt-based catalysts. This highly tunable method allows for methylation of both aromatic and aliphatic amines, and chemoselective methylation of aminoalcohols and diamines. Notably, the in situ-formed catalyst can also be used for the reduction of carbonates to methanol at room temperature. Mechanistic insights on intermediates formed during the reaction pathway were obtained by using ESI mass spectrometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. “A Long March to Room Temperature Superconductivity”

    CERN Multimedia

    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. Behaviour of actinides in room temperature ionic liquids

    International Nuclear Information System (INIS)

    Bosse, E.

    2008-07-01

    The room temperature ionic liquids are potentially interesting for the treatment of nuclear fuel. But the knowledge of the behaviour of actinides in the ionic liquids is fragmented because these solvents are new, young and many. In a first time, the ionic liquids [BuMeIm][Tf 2 N] and [MeBu 3 N][Tf 2 N] have been studied in α and γ irradiation with different atmosphere (argon and air) and concentrations of water. ESIMS, NMR and liquid chromatography coupled ESI-MS analysis demonstrate a multitude of degradation products but in very small quantities. This good radiolytic stability makes it a major advantage for the studies of actinides. In a second time, the interaction between an anionic complex of uranium (UCl 6 2- ) and the cation of the ionic liquid and too the study of the hydrolysis of An 4+ (An uranium, neptunium, plutonium) were conducted in different ionic liquids ([MeBu 3 N][Tf 2 N], [BuMe 2 Im][Tf 2 N] and [BuMeIm][Tf 2 N]). The experimental results showed that the intensity of these interactions between UCl 6 2- anion and the ionic liquid cation depends on the latter and follows the order: MeBu 3 N + ∼ BuMe 2 Im + ≤BuMeIm + . In addition, the results obtained by UV/Vis spectroscopy showed that the reaction of hydrolysis in the ionic liquids is slow, secondary compared to the oxidation or the disproportionation and that the amount of water in ionic liquid must be relatively large compared to the concentration of actinide. The results from the coupling of different analytical techniques (NMR, mass spectrometry, UV-Visible, Infra-red, Electrochemistry..) have allowed a first approach in the understanding of the actinides in the room temperature ionic liquids. (author)

  1. Room Temperature Dynamic Strain Aging in Ultrafine-Grained Titanium

    Science.gov (United States)

    Lopes, Felipe Perissé D.; Lu, Chia Hui; Zhao, Shiteng; Monteiro, Sergio N.; Meyers, Marc A.

    2015-10-01

    Dynamic strain aging (DSA) in coarse-grained (CG) titanium is usually observed at intermediate to high temperatures 473 K to 973 K (200 °C to 700 °C) and is characterized by serrations in the stress vs strain curves. In the present work, despite the absence of apparent serrations, ultrafine-grained titanium (UFG Ti) undergoes DSA at room temperature, exhibited through an abnormal increase in the elastic limit and negative strain rate sensitivity. This effect is observed at 293 K (20 °C) in the strain rate interval of 10-4 to 10-2 s-1, and at 203 K (-70 °C) and 373 K (100 °C) in a distinct strain rate range. Based on a calculated activation energy of 17.3 kJ/mol and microstructural observations by transmission electron microscopy, it is proposed that the dominant mechanism for DSA in UFG Ti involves interstitial solutes interacting with dislocations emitted from grain boundaries. The interstitials migrate from the grain boundaries along dislocation lines bowing out as they are emitted from the boundaries, a mechanism with a low calculated activation energy which is comparable with the experimental measurements. The dislocation velocities and interstitial diffusion along the dislocation cores are consistent.

  2. 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.

  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. Investigations of Cadmium Manganese Telluride Crystals for Room-Temperature Radiation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G.; Bolotnikov, A.; Camarda, G.; Cui, Y.; Hossain, A.; Kim, K.; Carcelen, V.; Gul, R.; James, R.

    2009-10-06

    Cadmium manganese telluride (CMT) has high potential as a material for room-temperature nuclear-radiation detectors. We investigated indium-doped CMT crystals taken from the stable growth region of the ingot, and compared its characteristics with that from the last-to-freeze region. We employed different techniques, including synchrotron white-beam X-ray topography (SWBXT), current-voltage (I-V) measurements, and low-temperature photoluminescence spectra, and we also assessed their responses as detectors to irradiation exposure. The crystal from the stable growth region proved superior to that from the last-to-freeze region; it is a single-grain crystal, free of twins, and displayed a resistivity higher by two orders-of-magnitude. The segregation of indium dopant in the ingot might be responsible for its better resistivity. Furthermore, we recorded a good response in the detector fabricated from the crystal taken from the stable growth region; its ({mu}{tau}){sub e} value was 2.6 x 10{sup -3} cm{sup 2}/V, which is acceptable for thin detectors, including for applications in medicine.

  5. 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.

  6. Mechanochemical Functionalization of Carbon Black at Room Temperature

    Directory of Open Access Journals (Sweden)

    Desirée Leistenschneider

    2018-02-01

    Full Text Available Carbon nanomaterials such as carbon blacks are intrinsically hydrophobic with limited wettability in aqueous media, thus restricting their potential applications. To improve their hydrophilicity, common methods tend to utilize harmful chemicals and conditions, such as a mixture of KMnO4 and H2SO4 or a complex and expensive synthesis setup. In our work, we report a simple method to improve the wettability of these materials by a mechanochemical treatment completed within 1 h at room-temperature utilizing a NH3 solution. Besides increasing the specific surface area of the carbon black from 67 m2·g−1 up to 307 m2·g−1, our process also incorporates nitrogen- and oxygen-containing functional groups into the carbon. This reduces the contact angle from 80° to 30°, confirming an enhanced wettability. Our work presents an easy, fast, and straightforward pathway towards the functionalization of carbon nanomaterials and can be of use in various applications where aqueous wettability is advantageous.

  7. All-Aluminum Thin Film Transistor Fabrication at Room Temperature

    Directory of Open Access Journals (Sweden)

    Rihui Yao

    2017-02-01

    Full Text Available Bottom-gate all-aluminum thin film transistors with multi conductor/insulator nanometer heterojunction were investigated in this article. Alumina (Al2O3 insulating layer was deposited on the surface of aluminum doping zinc oxide (AZO conductive layer, as one AZO/Al2O3 heterojunction unit. The measurements of transmittance electronic microscopy (TEM and X-ray reflectivity (XRR revealed the smooth interfaces between ~2.2-nm-thick Al2O3 layers and ~2.7-nm-thick AZO layers. The devices were entirely composited by aluminiferous materials, that is, their gate and source/drain electrodes were respectively fabricated by aluminum neodymium alloy (Al:Nd and pure Al, with Al2O3/AZO multilayered channel and AlOx:Nd gate dielectric layer. As a result, the all-aluminum TFT with two Al2O3/AZO heterojunction units exhibited a mobility of 2.47 cm2/V·s and an Ion/Ioff ratio of 106. All processes were carried out at room temperature, which created new possibilities for green displays industry by allowing for the devices fabricated on plastic-like substrates or papers, mainly using no toxic/rare materials.

  8. A room-temperature liquid calorimeter prototype for the SSC

    International Nuclear Information System (INIS)

    Brandenburg, G.W.; Geer, S.H.; Oliver, J.; Sadowski, E.; Theriot, D.

    1990-01-01

    Calorimeters will be an extremely important part of SSC detectors as they have been in existing collider detectors. The main issues that need to be addressed are: (1) energy resolution of jets and electrons, (2) segmentation, (3) hermiticity, (4) response time, and (5) radiation resistance. An attractive possibility on all these counts is the use of room-temperature liquids together with uranium, as pioneered by UA1. The authors are planning a prototype calorimeter which consists of a sealed vessel containing both the radiator plates and the readout pads. This geometry has been appropriately named the swimming pool design. The general mechanical starting point is similar to the SLD liquid argon calorimeters. The points they wish to address are the following: (1) Simple and reliable modular construction techniques, (2) Satisfactory electrical connections with minimal geometric impact, (3) The necessity of isolating radiator plates and liquid to maintain purity, (4) What materials can be immersed without compromising the liquid purity. The design and construction of the swimming pool electromagnetic calorimeter prototype is being carried out at the Harvard High Energy Physics Laboratory. This is one of the first attempts to build a full-scale prototype of such a design

  9. The γ radiolysis at room temperature of liquid deaerated isopropanol

    International Nuclear Information System (INIS)

    Gilles, L.

    1969-02-01

    The main products formed in the room temperature γ radiolysis of liquid isopropanol, and their respective yields, are: hydrogen 3.8, methane 1.6, acetone 3.4, acetaldehyde 1.1, and pinacol 0.3. These results give a material balance in good agreement with the formula of isopropanol and lead to a value for the yield of decomposition: 5, 3. The absence of butanediol 2.3 shows that the acetaldehyde cannot come from the dismutation of hydroxyethyl radicals. The variations of the hydrogen yield in the neutral medium with the concentration of added electron scavengers may be explained in terms of the model proposed by Freeman and FAYADH which supposes the existence of spurs. The yield of solvated electrons diffusing into the bulk of the solution and also the ratios of rate constants for the reactions of the scavengers with the electrons may likewise be obtained on the basis of this model. Certain effects not foreseen by this model may result from the capture of electrons solvated or not, whose mode of disappearance in pure alcohol remains unknown. One may distinguish a yield of excited molecules of at least 2, of which 80 per cent lead to the production of molecular hydrogen and 20 per cent to that of molecular methane, and an ionization yield of 2. 2. The discussion of the various mechanisms which may lead to the formation of the products indicates that these yields may be higher than the values quoted. (author) [fr

  10. 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.

  11. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rajpurohit, R.S., E-mail: rsrajpurohit.rs.met13@iitbhu.ac.in [Department of Metallurgical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi, 221005 (India); Sudhakar Rao, G. [Nuclear Energy and Safety Department, Paul Scherrer Institute, Villigen, CH-5232 (Switzerland); Chattopadhyay, K.; Santhi Srinivas, N.C.; Singh, Vakil [Department of Metallurgical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi, 221005 (India)

    2016-08-15

    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. - Highlights: • Ratcheting strain accumulation occurred due to asymmetric cyclic loading. • Accumulation of ratcheting strain increased with mean stress and stress amplitude. • Ratcheting strain accumulation decreased with increase in stress rate. • With increase in mean stress and stress amplitude there was reduction in fatigue life. • Fatigue life is improved with increase in stress rate.

  13. Unveiling the uncatalyzed reaction of alkynes with 1,2-dipoles for the room temperature synthesis of cyclobutenes.

    Science.gov (United States)

    Alcaide, Benito; Almendros, Pedro; Fernández, Israel; Lázaro-Milla, Carlos

    2015-02-25

    2-(Pyridinium-1-yl)-1,1-bis(triflyl)ethanides have been used as 1,2-dipole precursors in a metal-free direct [2+2] cycloaddition reaction of alkynes. Starting from stable zwitterionic pyridinium salts, the electron deficient olefin 1,1-bis(trifluoromethylsulfonyl)ethene is generated in situ and immediately reacted at room temperature with an alkyne to afford substituted cyclobutenes. Remarkably, this mild and facile uncatalyzed protocol requires neither irradiation nor heating.

  14. Possible mechanism for the room-temperature stabilization of the Ge(111) T > 300 deg.C phase by Ga

    DEFF Research Database (Denmark)

    Böhringer, M.; Molinás-Mata, P.; Zegenhagen, J.

    1995-01-01

    At low coverages, Ga on Ge(111) induces a hexagonal, domain wall modulated (2 x 2) adatom phase, stable at room temperature, that is characterized in low energy electron diffraction (LEED) by split 1/2-order reflections. This pattern closely resembles the one observed for a phase of clean Ge(111......) appearing at temperatures above 300 degrees C (T > 300 degrees C phase). We report scanning tunneling microscopy, LEED, as well. as surface x-ray diffraction measurements on the Ga-induced room-temperature (RT) phase and compare it with a model for the T > 300 OC phase of clean Ge(111). RT deposition of Ga...... yields a metastable c(2 x 8) structure which upon annealing transforms to the hexagonal (2 x 2) one. The transition occurs at considerably lower temperatures compared to clean Ge(111) and is irreversible due to pinning of adatom domains at Ga-induced defects, preventing the reordering of the adatoms...

  15. Colloquium: High pressure and road to room temperature superconductivity

    Science.gov (United States)

    Gor'kov, Lev P.; Kresin, Vladimir Z.

    2018-01-01

    future use of tunneling spectroscopy. This feature leads to nonmonotonic and strongly asymmetric pressure dependence of Tc . Other hydrides, e.g., CaH6 and MgH6 , can be expected to display even higher values of Tc up to room temperature. The fundamental challenge lies in the creation of a structure capable of displaying high Tc at ambient pressure.

  16. 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.

  17. Formation of magnetite nanoparticles at low temperature: from superparamagnetic to stable single domain particles.

    Directory of Open Access Journals (Sweden)

    Jens Baumgartner

    Full Text Available The room temperature co-precipitation of ferrous and ferric iron under alkaline conditions typically yields superparamagnetic magnetite nanoparticles below a size of 20 nm. We show that at pH  =  9 this method can be tuned to grow larger particles with single stable domain magnetic (> 20-30 nm or even multi-domain behavior (> 80 nm. The crystal growth kinetics resembles surprisingly observations of magnetite crystal formation in magnetotactic bacteria. The physicochemical parameters required for mineralization in these organisms are unknown, therefore this study provides insight into which conditions could possibly prevail in the biomineralizing vesicle compartments (magnetosomes of these bacteria.

  18. Polyaniline-Cadmium Ferrite Nanostructured Composite for Room-Temperature Liquefied Petroleum Gas Sensing

    Science.gov (United States)

    Kotresh, S.; Ravikiran, Y. T.; Tiwari, S. K.; Vijaya Kumari, S. C.

    2017-08-01

    We introduce polyaniline-cadmium ferrite (PANI-CdFe2O4) nanostructured composite as a room-temperature-operable liquefied petroleum gas (LPG) sensor. The structure of PANI and the composite prepared by chemical polymerization was characterized by Fourier-transform infrared (FT-IR) spectroscopy, x-ray diffraction (XRD) analysis, and field-emission scanning electron microscopy. Comparative XRD and FT-IR analysis confirmed CdFe2O4 embedded in PANI matrix with mutual interfacial interaction. The nanostructure of the composite was confirmed by transmission electron microscopy. A simple LPG sensor operable at room temperature, exclusively based on spin-coated PANI-CdFe2O4 nanocomposite, was fabricated with maximum sensing response of 50.83% at 1000 ppm LPG. The response and recovery time of the sensor were 50 s and 110 s, respectively, and it was stable over a period of 1 month with slight degradation of 4%. The sensing mechanism is discussed on the basis of the p- n heterojunction barrier formed at the interface of PANI and CdFe2O4.

  19. Trivalent europium speciation in a room-temperature ionic liquid

    International Nuclear Information System (INIS)

    Mekki, S.

    2006-10-01

    Since the nuclear industry is playing an important role in the power production field, a relevant number of problems have been revealed. Indeed, high-level radioactive long-lived nuclear wastes present a real difficulty for nuclear wastes management. Minor actinides, which compose most of these wastes, will be radioactive for several thousands of years. For eventual disposal deep underground, their reprocessing needs to be optimized. The extraction processes used industrially to separate actinides and lanthanides from other metal species characterizing the spent nuclear fuel produce, nevertheless, enormous quantities of contaminated liquid wastes directly issued from the liquid/liquid extraction step. During the last decade, some room-temperature ionic liquid have been studied and integrated into industrial processes. The interest on this class of solvent came out from their 'green' properties (non volatile, non flammable, recyclable, etc...), but also from the variability of their physico-chemical properties (stability, hydrophobicity, viscosity) as a function of the RTIL chemical composition. Indeed, it has been shown that classical chemical industrial processes could be transferred into those media, even more improved, while a certain number of difficulties arising from using traditional solvent can be avoided. In this respect, it could be promising to investigate the ability to use room-temperature ionic liquid into the spent nuclear fuel reprocessing field. The aim of this thesis is to test the ability of the specific ionic liquid bumimTf 2 N to allow trivalent europium extraction. The choice of this metal is based on the chemical analogy with trivalent minor actinides Curium and Americium which are contributing the greatest part of the long-lived high-level radioactive wastes. Handling these elements needs to be very cautious for the safety and radioprotection aspect. Moreover, europium is a very sensitive luminescent probe to its environment even at the

  20. Exchange of hydrogen isotopes in oxide ceramics at room temperature

    International Nuclear Information System (INIS)

    Suzuki, H.; Morita, K.; Soda, K.

    2001-01-01

    The decay curves of D and up-take curves of H on the exchange of D implanted into Li 2 TiO 3 for H in H 2 O vapor caused by exposure to normal-air at room temperature have been measured as a function of exposure time at different implantation concentrations by means of the elastic recoil detection technique. The re-emission curves of D retained and H up-taken in a specimen by isochronal annealing for 10 min have been also measured. It is found that the thermal re-emission of D and H takes place uniformly over the whole specimen due to local molecular recombination in the bulk and that the re-emission rates of H and D in the near-surface layers are slower than those in the deeper layers. It is also found that the decay of D caused by the D-H exchange takes place rapidly in the beginning and the retained amount of D attains at a constant level and the retained fraction of D are higher as the initial implantation concentrations of D are lower. The decay curves of D and the up-take curves of H have been analysed using the mass balance equations, in which the elementary processes are taken into account according to the exchange model of one way diffusion from the surface into the bulk. It is shown that the solution of the mass balance equations reproduces well the experimental data. The rate constants of the elementary processes determined are discussed. (orig.)

  1. 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.

  2. 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

  3. 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

  4. Bismuth oxide film: a promising room-temperature quantum spin Hall insulator

    Science.gov (United States)

    Wang, Ya-Ping; Li, Sheng-Shi; Ji, Wei-Xiao; Zhang, Chang-Wen; Li, Ping; Wang, Pei-Ji

    2018-03-01

    Two-dimensional (2D) bismuth films have attracted extensive attention due to their nontrivial band topology and tunable electronic properties for achieving dissipationless transport devices. The experimental observation of quantum transport properties, however, are rather challenging, limiting their potential application in nanodevices. Here, we predict, based on first-principles calculations, an alternative 2D bismuth oxide, BiO, as an excellent topological insulator (TI), whose intrinsic bulk gap reaches up to 0.28 eV. Its nontrivial topology is confirmed by topological invariant Z 2 and time-reversal symmetry protected helical edge states. The appearance of topological phase is robust against mechanical strain and different levels of oxygen coverage in BiO. Since the BiO is naturally stable against surface oxidization and degradation, these results enrich the topological materials and present an alternative way to design topotronics devices at room temperature.

  5. Electrodeposition at room temperature of amorphous silicon and germanium nanowires in ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Martineau, F; Namur, K; Mallet, J; Delavoie, F; Troyon, M; Molinari, M [Laboratoire de Microscopies et d' Etude de Nanostructures (LMEN EA3799), Universite de Reims Champagne Ardennes (URCA), Reims Cedex 2 (France); Endres, F, E-mail: michael.molinari@univ-reims.fr [Institute of Particle Technology, Chair of Interface Processes, Clausthal University of Technology, D-36678 Clausthal-Zellerfeld (Germany)

    2009-11-15

    The electrodeposition at room temperature of silicon and germanium nanowires from the air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P{sub 1,4}) containing SiCl{sub 4} as Si source or GeCl{sub 4} as Ge source is investigated by cyclic voltammetry. By using nanoporous polycarbonate membranes as templates, it is possible to reproducibly grow pure silicon and germanium nanowires of different diameters. The nanowires are composed of pure amorphous silicon or germanium. The nanowires have homogeneous cylindrical shape with a roughness of a few nanometres on the wire surfaces. The nanowires' diameters and lengths well match with the initial membrane characteristics. Preliminary photoluminescence experiments exhibit strong emission in the near infrared for the amorphous silicon nanowires.

  6. 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...

  7. Room-temperature ferromagnetic properties of Cu-doped ZnO rod ...

    Indian Academy of Sciences (India)

    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.

  8. Low cycle fatigue strength of some austenitic stainless steels at room temperature and elevated temperatures

    International Nuclear Information System (INIS)

    Type 304, 316, and 316L stainless steels were tested from room temperature to 650 0 C using two kinds of bending test specimens. Particularly, Type 304 was tested at several cyclic rates and 550 0 and 650 0 C, and the effect of cyclic rate on its fatigue strength was investigated. Test results are summarized as follows: (1) The bending fatigue strength at room temperature test shows good agreement with the axial fatigue one, (2) Manson--Coffin's fatigue equation can be applied to the results, (3) the ratio of crack initiation to failure life becomes larger at higher stress level, and (4) the relation between crack propagation life and total strain range or elastic strain range are linear in log-log scale. This relation also agrees with the equations which were derived from some crack propagation laws. It was also observed at the elevated temperature test: (1) The reduction of fatigue strength is not noticeable below 500 0 C, but it is noted at higher temperature. (2) The cycle rate does not affect on fatigue strength in faster cyclic rate than 20 cpm and below 100,000 cycles life range. (3) Type 316 stainless steel shows better fatigue property than type 304 and 316L stainless steels. 30 figures

  9. Temperature-amplitude coupling for stable biological rhythms at different temperatures.

    Science.gov (United States)

    Kurosawa, Gen; Fujioka, Atsuko; Koinuma, Satoshi; Mochizuki, Atsushi; Shigeyoshi, Yasufumi

    2017-06-01

    Most biological processes accelerate with temperature, for example cell division. In contrast, the circadian rhythm period is robust to temperature fluctuation, termed temperature compensation. Temperature compensation is peculiar because a system-level property (i.e., the circadian period) is stable under varying temperature while individual components of the system (i.e., biochemical reactions) are usually temperature-sensitive. To understand the mechanism for period stability, we measured the time series of circadian clock transcripts in cultured C6 glioma cells. The amplitudes of Cry1 and Dbp circadian expression increased significantly with temperature. In contrast, other clock transcripts demonstrated no significant change in amplitude. To understand these experimental results, we analyzed mathematical models with different network topologies. It was found that the geometric mean amplitude of gene expression must increase to maintain a stable period with increasing temperatures and reaction speeds for all models studied. To investigate the generality of this temperature-amplitude coupling mechanism for period stability, we revisited data on the yeast metabolic cycle (YMC) period, which is also stable under temperature variation. We confirmed that the YMC amplitude increased at higher temperatures, suggesting temperature-amplitude coupling as a common mechanism shared by circadian and 4 h-metabolic rhythms.

  10. A stable boundary layer perspective on global temperature trends

    International Nuclear Information System (INIS)

    McNider, R T; Christy, J R; Biazar, A

    2010-01-01

    temperatures in the stable boundary layer are not very robust measures of the heat content in the deep atmosphere and climate models do not predict minimum temperatures well, minimum temperatures should not be used as a surrogate for measures of deep atmosphere global warming.

  11. Hydrogen absorption/desorption characteristics of room temperature ...

    Indian Academy of Sciences (India)

    Administrator

    site element increases. This trend suggests that ZrCr2 and. ZrMn2 form the most stable hydrides and ZrNi2 forms the least stable hydride. Thus, we ..... Bogdanovic B, Brand R A, Marjanovic A, Schwickardi M and. Tölle J 2000 J. Alloys Compd. 302 36. Douglas G, Ivey, Derek O and Northwood 1996 Z. Phys. Chem. 147 191.

  12. Charpy impact properties and failure mechanism of 3D MWK composites at room and cryogenic temperatures

    Science.gov (United States)

    Li, Dian-sen; Jiang, Nan; Zhao, Chuang-qi; Jiang, Lei; Tan, Yi

    2014-07-01

    The charpy impact experiments on the 3D MWK (Multi-axial warp knitted) composites with four different fiber architectures are performed at room (20 °C) and liquid nitrogen temperatures (as low as -196 °C). Macro-Fracture morphology and SEM micrographs are examined to understand the impact deformation and failure mechanism. The results show that the impact properties decrease significantly with the increase of the fiber ply angle at both room and liquid nitrogen temperatures. Meanwhile, the impact energy at liquid nitrogen temperature has been improved significantly than that at room temperature. Moreover, the fiber architecture has remarkable effect on the impact damage and failure patterns of composites at room and liquid nitrogen temperatures. At liquid nitrogen temperature, the matrix solidification and the interfacial adhesion capacity increase greatly, which effectively hinders the stress wave propagation. However, more micro-cracks appear and the brittle failure feature becomes more obvious.

  13. White wine proteins: how does the pH affect their conformation at room temperature?

    Science.gov (United States)

    Dufrechou, Marie; Vernhet, Aude; Roblin, Pierre; Sauvage, François-Xavier; Poncet-Legrand, Céline

    2013-08-20

    Our studies focused on the determination of aggregation mechanisms of proteins occurring in wine at room temperature. Even if the wine pH range is narrow (2.8 to 3.7), some proteins are affected by this parameter. At low pH, the formation of aggregates and the development of a haze due to proteins sometimes occur. The objective of this work was to determine if the pH impacted the conformational stability of wine proteins. Different techniques were used: circular dichroism and fluorescence spectroscopy to investigate the modification of their secondary and tertiary structure and also SAXS to determine their global shape. Four pure proteins were used, two considered to be stable (invertase and thaumatin-like proteins) and two considered to be unstable (two chitinase isoforms). Two pH values were tested to emphasize their behavior (pH 2.5 and 4.0). The present work highlighted the fact that the conformational stability of some wine proteins (chitinases) was impacted by partial modifications, related to the exposure of some hydrophobic sites. These modifications were enough to destabilize the native state of the protein. These modifications were not observed on wine proteins determined to be stable (invertase and thaumatin-like proteins).

  14. Pretreated Lignocellulosic Waste Mediated Biosynthesis of Silver Nanoparticles Under Room Temperature

    Science.gov (United States)

    Manjamadha, V. P.; Muthukumar, Karuppan

    2016-10-01

    The current work elucidates the utilization of biowaste as a valuable reducing agent for the synthesis of silver nanoparticles. In this study, the wastewater generated during the alkaline pretreatment of lignocellulosic wastes (APLW) was used as a bioreductant to reduce silver nitrate under room temperature. Synthesis of stable silver nanoparticles (AgNPs) was achieved rapidly on addition of APLW into the silver nitrate solution (1mM). The morphological characterization of AgNPs was performed using field emission scanning electron microscopy (FESEM). The micrograph clearly depicted the presence of spherical AgNPs. The presence of elemental silver along with biomoilties was determined using energy dispersive X-ray spectroscopy (EDAX) analysis. The X-ray diffraction (XRD) study proved the crystalline form of stable AgNPs. The AgNPs exhibited excellent antibacterial performance against Gram negative organism. The immediate bioreduction of silver ions using APLW was well illustrated in the present study. Thus, APLW serve as an alternative source for reducing agents instead of utilizing valuable medicinal plants for nanoparticles synthesis.

  15. Impacts of exhalation flow on the microenvironment around the human body under different room temperatures

    Science.gov (United States)

    Jafari, Mohammad Javad; Gharari, Noradin; Azari, Mansour Rezazade; Ashrafi, Khosro

    2018-04-01

    Exhalation flow and room temperature can have a considerable effect on the microenvironment in the vicinity of human body. In this study, impacts of exhalation flow and room temperature on the microenvironment around a human body were investigated using a numerical simulation. For this purpose, a computational fluid dynamic program was applied to study thermal plume around a sitting human body at different room temperatures of a calm indoor room by considering the exhalation flow. The simulation was supported by some experimental measurements. Six different room temperatures (18 to 28 °C) with two nose exhalation modes (exhalation and non-exhalation) were investigated. Overhead and breathing zone velocities and temperatures were simulated in different scenarios. This study finds out that the exhalation through the nose has a significant impact on both quantitative and qualitative features of the human microenvironment in different room temperatures. At a given temperature, the exhalation through the nose can change the location and size of maximum velocity at the top of the head. In the breathing zone, the effect of exhalation through the nose on velocity and temperature distribution was pronounced for the point close to mouth. Also, the exhalation through the nose strongly influences the thermal boundary layer on the breathing zone while it only minimally influences the convective boundary layer on the breathing zone. Overall results demonstrate that it is important to take the exhalation flow into consideration in all areas, especially at a quiescent flow condition with low temperature.

  16. 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

  17. A facile route for irreversible bonding of plastic-PDMS hybrid microdevices at room temperature.

    Science.gov (United States)

    Tang, Linzhi; Lee, Nae Yoon

    2010-05-21

    Plastic materials do not generally form irreversible bonds with poly(dimethylsiloxane) (PDMS) regardless of oxygen plasma treatment and a subsequent thermal process. In this paper, we perform plastic-PDMS bonding at room temperature, mediated by the formation of a chemically robust amine-epoxy bond at the interfaces. Various plastic materials, such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polyimide (PI), and poly(ethylene terephthalate) (PET) were adopted as choices for plastic materials. Irrespective of the plastic materials used, the surfaces were successfully modified with amine and epoxy functionalities, confirmed by the surface characterizations such as water contact angle measurements and X-ray photoelectron spectroscopy (XPS), and chemically robust and irreversible bonding was successfully achieved within 1 h at room temperature. The bonding strengths of PDMS with PMMA and PC sheets were measured to be 180 and 178 kPa, respectively, and their assemblies containing microchannel structures endured up to 74 and 84 psi (510 and 579 kPa) of introduced compressed air, respectively, without destroying the microdevices, representing a robust and highly stable interfacial bonding. In addition to microchannel-molded PDMS bonded with flat plastic substrates, microchannel-embossed plastics were also bonded with a flat PDMS sheet, and both types of bonded assemblies displayed sufficiently robust bonding, tolerating an intense influx of liquid whose per-minute injection volume was nearly 1000 to 2000 times higher than the total internal volume of the microchannel used. In addition to observing the bonding performance, we also investigated the potential of surface amine and epoxy functionalities as durable chemical adhesives by observing their storage-time-dependent bonding performances.

  18. New, room-temperature gamma-ray detector for improved assay of plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Russo, P.A.; Meier, A.P.; Rawool-Sullivan, M. [and others

    1997-11-01

    Gamma-ray spectroscopy for portable and unattended assay of nuclear materials requires rugged, reliable, room-temperature detectors that are stable in variable environments and detect gamma rays with good efficiency and energy resolution. For portable assays especially, compact detectors address needs for large numbers of measurements performed in rapid succession with heavy shielding and collimation by a user who must carry the spectroscopy equipment. Most measurements are made with compact NaI detectors. The assay of variable-burnup plutonium and other plutonium materials of variable isotopic composition challenges low-resolution gamma-ray spectroscopy in numerous safeguards applications including holdup measurements, safeguards inspections, monitoring, and safeguards close-out in decontamination and decommissioning. A new, commercial-prototype coplanar-grid CdZnTe detector has been evaluated using the assay of variable-burnup plutonium as a metric indicator to show the substantial benefit of its improved performance compared to results of the same measurements performed with the compact NaI detector. Detector performance, spectrum-quality, and assay results as well as gamma-ray spectra of reference sources are compared for the coplanar-grid CdZnTe and compact NaI detectors to illustrate the advantages of the new room-temperature gamma-ray detector. Isotope identification with the coplanar-grid CdZnTe detector is demonstrated. Preliminary calculations (Monte Carlo coupled to simulations of radiation transport and charge collection) of the spectral response of the detector to plutonium indicate promise for the use of the coplanar-grid CdZnTe detector for further improvements in the accuracy of assays and for analysis of gamma-ray isotopic distributions.

  19. Interrelation between mean radiant temperature and room geometry

    OpenAIRE

    Kalmár, Ferenc; Kalmár, Tünde

    2012-01-01

    Energy saving is one of the most important research directions in the building sector. Daily new HVAC solutions and equipments are developed aiming higher efficiency and lower fossil fuel utilisation. There are cases when only the energy quantity is taken into account and the human side of the problem is neglected. The new energy saving ideas should be analysed from thermal comfort point too. The aim of our research was to see which the influence of the room geometry on the mean radiant tempe...

  20. Temperature Compensated Sapphire Resonator for Ultra-Stable Oscillator Capability at Temperatures Above 77 Kelvin

    Science.gov (United States)

    Dick, G.; Santiago, D.; Wang, R.

    1994-01-01

    We report on the design and test of a whispering gallery sapphire resonator for which the dominant (WGH xxxsubn11) microwave mode family shows frequency-stable, compensated operation for temperatures above 77 Kelvin. The resonator makes possible a new ultra-stable oscillator (USO) capability that promises performance improvements over the best available crystal quartz oscillators in a compact cryogenic package. A mechanical compensation mechanism, enabled by the difference between copper and sapphire expansion coefficients, tunes the resonator to cancel the temperature variation of sapphire's dielectric constant.

  1. Tunable room-temperature single photon emission from atomic defects in hexagonal boron nitride

    Science.gov (United States)

    Grosso, Gabriele; Moon, Hyowon; Lienhard, Benjamin; Efetov, Dmitri; Furchi, Marco; Jarillo-Herrero, Pablo; Ali, Sajid; Ford, Michael; Aharonovich, Igor; Englund, Dirk

    Two-dimensional van der Waals materials have emerged as promising platforms for solid-state quantum information processing devices with unusual potential for heterogeneous assembly. Recently, bright and photostable single photon emitters were reported from atomic defects in layered hexagonal boron nitride (hBN), but controlling inhomogeneous spectral distribution and reducing multi-photon emission presented open challenges. We demonstrate that strain control allows spectral tunability of hBN single photon emitters, and material processing sharply improves the single-photon purity. Our sample fabrication process relies on ion irradiation and high temperature annealing to isolate individual defects for single photon emission. Spectroscopy on this emitter reports high single photon purity of g(2)(0) =0.07, and high count rates exceeding 107 counts/sec at saturation. Furthermore, these emitters are stable to material transfer to other substrates, including a bendable beam that allows us to controllably apply strain. Our experiments indicate a maximum tuning of 6 meV and emission energy dependencies ranging from -3 to 6 meV/%. High-purity and photostable single photon emission at room temperature, together with spectral tunability and transferability, opens the door to scalable integration of high-quality quantum emitters in photonic quantum technologies.

  2. Red photoluminescence of living systems at the room temperature: measurements and results

    International Nuclear Information System (INIS)

    Kudryashova, I S; Rud, V Yu; Shpunt, V Ch; Rud, Yu V; Glinushkin, A P

    2016-01-01

    Presents results of a study of the red luminescence of living plants at room temperature. The analysis of obtained results allows to conclude that the photoluminescence spectra for green leaves in all cases represent the two closely spaced bands. (paper)

  3. ROOM TEMPERATURE BULK AND TEMPLATE-FREE SYNTHESIS OF LEUCOEMARLDINE POLYANILINE NANOFIBERS

    Science.gov (United States)

    Herein, we describe a simple strategy for the bulk and template-free synthesis of reduced leucoemarldine polyaniline nanofibers size ranging from as low as 10 nm to 50 nm without the use of any reducing agents at room temperature.

  4. Room-Temperature Single-Photon Source for Secure Quantum Communication

    Data.gov (United States)

    National Aeronautics and Space Administration — We are asking for four years of support for PhD student Justin Winkler's work on a research project entitled "Room temperature single photon source for secure...

  5. Temperature autocontrol system for the coud%eacute; room of the 1.2 m telescope

    Science.gov (United States)

    Zhang, Jian-Hua

    The setting up of temperature autocontrol system for the coudé room of the 1.2 m telescope at Yunnan Observatory and realizing the airflow autocirculation, purified the air, keeping the temperature in the coudé room constantly by autocontrol the heater, and then keeping the optical system in the best condition are introduced in this paper. The autocontrol system is designed and developed at the basis of having only the air circulator and the heater controlled by hand.

  6. Room-Temperature Hysteresis in a Hole-Based Quantum Dot Memory Structure

    Directory of Open Access Journals (Sweden)

    Tobias Nowozin

    2013-01-01

    Full Text Available We demonstrate a memory effect in self-assembled InAs/Al0.9Ga0.1As quantum dots (QDs near room temperature. The QD layer is embedded into a modulation-doped field-effect transistor (MODFET which allows to charge and discharge the QDs and read out the logic state of the QDs. The hole storage times in the QDs decrease from seconds at 200 K down to milliseconds at room temperature.

  7. In situ TEM Nanomechanical Testing of Ceramics: Room-Temperature Plastic Deformation Mechanisms

    OpenAIRE

    Kiani, Sara

    2014-01-01

    This dissertation presents the investigation of the effects of size-scale and crystallographic orientation on room-temperature plastic deformation of ceramics. Using in situ electron microscopy based nanomechanical testing, I show that sub-micron-scale single-crystalline refractory carbides exhibit size- and orientation-dependent room-temperature plasticity under uniaxial compression. Refractory carbides such as ZrC, TaC and SiC - chosen as candidate materials - owing to their high hardness (...

  8. 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.

  9. 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.

  10. Model predictive control of room temperature with disturbance compensation

    Science.gov (United States)

    Kurilla, Jozef; Hubinský, Peter

    2017-08-01

    This paper deals with temperature control of multivariable system of office building. The system is simplified to several single input-single output systems by decoupling their mutual linkages, which are separately controlled by regulator based on generalized model predictive control. Main part of this paper focuses on the accuracy of the office temperature with respect to occupancy profile and effect of disturbance. Shifting of desired temperature and changing of weighting coefficients are used to achieve the desired accuracy of regulation. The final structure of regulation joins advantages of distributed computing power and possibility to use network communication between individual controllers to consider the constraints. The advantage of using decoupled MPC controllers compared to conventional PID regulators is demonstrated in a simulation study.

  11. A theoretical study of ZnO-GS nanosensor to detect H{sub 2}S at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi-Manesh, E., E-mail: emanesh@mail.kntu.ac.ir; Rahmani, S.

    2017-05-01

    In this paper, to detect hydrogen sulfide (H{sub 2}S) gas. the electronic structure, density of states, charge population analysis and electrical conductivity change at room temperature for Zinc oxide decorated graphene sheets (ZnO-GS) nanostructure were studied in detail. The calculations were performed using Density Functional Theory. The results strongly showed that the ZnO-GS nanostructure could be used as a nanosensor to detect H{sub 2}S gas at room temperature. Based on this set of calculations, H{sub 2}S adsorption energy on ZnO-GS showed a significant increase compared to the pure graphene sheets. The electrical conductivity of ZnO-GS was significantly changed at room temperature, after adsorption of H{sub 2}S. Based on these studies, the ZnO-GS nanosensor can be used to detect H{sub 2}S. Obtained results are in excellent agreement with reported experimental results. - Highlights: • Adsorption mechanism of H{sub 2}S on ZnO-GS nanosensors are studied. • The most stable configuration of each structure is obtained by using DFT method. • Electrical conductance of ZnO-GS before and after adsorption H{sub 2}S are calculated. • ZnO-GS nanosensor has more sensitivity in H{sub 2}S detection.

  12. 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...

  13. 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.

  14. Structure determination at room temperature and phase transition ...

    Indian Academy of Sciences (India)

    Unknown

    displacement of Bi atoms along the 'a' axis might be responsible for ferroelectricity in these compounds. The high temperature X-ray data above Tc indicate no structural transition for A = Ba and Pb while A = Sr transforms to the tetragonal structure. Keywords. ab initio structure; powder XRD; Rietveld refinement; Aurivillius ...

  15. Electrospun polymer membrane activated with room temperature ionic liquid: Novel polymer electrolytes for lithium batteries

    Science.gov (United States)

    Cheruvally, Gouri; Kim, Jae-Kwang; Choi, Jae-Won; Ahn, Jou-Hyeon; Shin, Yong-Jo; Manuel, James; Raghavan, Prasanth; Kim, Ki-Won; Ahn, Hyo-Jun; Choi, Doo Seong; Song, Choong Eui

    A new class of polymer electrolytes (PEs) based on an electrospun polymer membrane incorporating a room-temperature ionic liquid (RTIL) has been prepared and evaluated for suitability in lithium cells. The electrospun poly(vinylidene fluoride- co-hexafluoropropylene) P(VdF-HFP) membrane is activated with a 0.5 M solution of LiTFSI in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) or a 0.5 M solution of LiBF 4 in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF 4). The resulting PEs have an ionic conductivity of 2.3 × 10 -3 S cm -1 at 25 °C and anodic stability at >4.5 V versus Li +/Li, making them suitable for practical applications in lithium cells. A Li/LiFePO 4 cell with a PE based on BMITFSI delivers high discharge capacities when evaluated at 25 °C at the 0.1 C rate (149 mAh g -1) and the 0.5 C rate (132 mAh g -1). A very stable cycle performance is also exhibited at these low current densities. The properties decrease at the higher, 1 C rate, when operated at 25 °C. Nevertheless, improved properties are obtained at a moderately elevated temperature of operation, i.e. 40 °C. This is attributed to enhanced conductivity of the electrolyte and faster reaction kinetics at higher temperatures. At 40 °C, a reversible capacity of 140 mAh g -1 is obtained at the 1 C rate.

  16. The effects of heated and room-temperature abdominal lavage solutions on core body temperature in dogs undergoing celiotomy.

    Science.gov (United States)

    Nawrocki, Michael A; McLaughlin, Ron; Hendrix, P K

    2005-01-01

    To document the magnitude of temperature elevation obtained with heated lavage solutions during abdominal lavage, 18 dogs were lavaged with sterile isotonic saline intraoperatively (i.e., during a celiotomy). In nine dogs, room-temperature saline was used. In the remaining nine dogs, saline heated to 43+/-2 degrees C (110+/-4 degrees F) was used. Esophageal, rectal, and tympanic temperatures were recorded every 60 seconds for 15 minutes after initiation of the lavage. Temperature levels decreased in dogs lavaged with room-temperature saline. Temperature levels increased significantly in dogs lavaged with heated saline after 2 to 6 minutes of lavage, and temperatures continued to increase throughout the 15-minute lavage period.

  17. 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).

  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. Applications of Fast, Facile, Radiation-Free Radical Polymerization Techniques Enabled by Room Temperature Alkylborane Chemistry.

    Science.gov (United States)

    Ahn, Dongchan; Wier, Kevin A; Mitchell, Timothy P; Olney, Patricia A

    2015-11-04

    Fast, robust, and scalable techniques for covalent materials assembly are shown to be enabled by variants of a simple mixing-induced free radical initiation scheme broadly termed room-temperature alkylborane (RTA) chemistry. Unique process versatility, speed of reaction, high conversion, and structural control at ambient conditions occur by exploiting air-stable alkylborane-amine complexes that rapidly initiate upon mixing with common amine-reactive decomplexing agents such as carboxylic acid compounds. Three diverse application examples are presented, illustrating facile ambient routes to covalent assembly varying in length scale: (1) copolymers with controllable pressure-sensitive adhesive properties, (2) hydrophilically modified silicone microparticles from heterophase reactions, and (3) UV-free inkjet printable materials suitable for thick-textured patterning and printing, all conducted in open air with no radiation or atmospheric control. These examples demonstrate that this simple "bucket chemistry" can create intriguing degrees of freedom for polymerization, cross-linking and covalent macromolecular assembly with controllable structure and properties, suggesting further opportunities for both fundamental mechanistic investigation and application to a range of old and new materials assembly problems across length scales.

  20. Microplastic Deformation of Submicrocrystalline Copper at Room and Elevated Temperatures

    Science.gov (United States)

    Dudarev, E. F.; Pochivalova, G. P.; Tabachenko, A. N.; Maletkina, T. Yu.; Skosyrskii, A. B.; Osipov, D. A.

    2017-02-01

    of investigations of submicrocrystalline copper subjected to cold rolling after abc pressing by methods of backscatter electron diffraction and x-ray diffraction analysis are presented. It is demonstrated that after such combined intensive plastic deformation, the submicrocrystalline structure with average grain-subgrain structure elements having sizes of 0.63 μm is formed with relative fraction of high-angle grain boundaries of 70% with texture typical for rolled copper. Results of investigation of microplastic deformation of copper with such structure at temperatures in the interval 295-473 K and with submicrocrystalline structure formed by cold rolling of coarse-grained copper are presented.

  1. 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.

  2. Room temperature ferromagnetic and semiconducting properties of graphene adsorbed with cobalt oxide using electrochemical method

    Science.gov (United States)

    Park, Chang-Soo; Lee, Kyung Su; Chu, Dongil; Lee, Juwon; Shon, Yoon; Kim, Eun Kyu

    2017-12-01

    We report the room temperature ferromagnetic properties of graphene adsorbed by cobalt oxide using electrochemical method. The cobalt oxide doping onto graphene was carried out in 0.1 M LiCoO2/DI-water solution. The doped graphene thin film was determined to be a single layer from Raman analysis. The CoO doped graphene has a clear ferromagnetic hysteresis at room temperature and showed a remnant magnetization, 128.2 emu/cm3. The temperature dependent conductivity of the adsorbed graphene showed the semiconducting behavior and a band gap opening of 0.12 eV.

  3. Room Temperature Hard Radiation Detectors Based on Solid State Compound Semiconductors: An Overview

    Science.gov (United States)

    Mirzaei, Ali; Huh, Jeung-Soo; Kim, Sang Sub; Kim, Hyoun Woo

    2018-03-01

    Si and Ge single crystals are the most common semiconductor radiation detectors. However, they need to work at cryogenic temperatures to decrease their noise levels. In contrast, compound semiconductors can be operated at room temperature due to their ability to grow compound materials with tunable densities, band gaps and atomic numbers. Highly efficient room temperature hard radiation detectors can be utilized in biomedical diagnostics, nuclear safety and homeland security applications. In this review, we discuss room temperature compound semiconductors. Since the field of radiation detection is broad and a discussion of all compound materials for radiation sensing is impossible, we discuss the most important materials for the detection of hard radiation with a focus on binary heavy metal semiconductors and ternary and quaternary chalcogenide compounds.

  4. Synthesis and characterization of nano crystalline nickel zinc ferrite for chlorine gas sensor at room temperature

    Science.gov (United States)

    Pawar, C. S.; Gujar, M. P.; Mathe, V. L.

    2015-06-01

    Nano crystalline Nickel Zinc ferrite (Ni0.25Zn0.75Fe2O4) thin films were synthesized by Sol Gel method for gas response. The phase and microstructure of the obtained Ni0.25Zn0.75Fe2O4 thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The nanostructured Ni0.25Zn0.75Fe2O4 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 Ni0.25Zn0.75Fe2O4 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.

  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

  6. Room temperature Compton profiles of conduction electrons in α-Ga ...

    Indian Academy of Sciences (India)

    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, ...

  7. Temperature sensing based on multimodal interference in polymer optical fibers: Room-temperature sensitivity enhancement by annealing

    Science.gov (United States)

    Kawa, Tomohito; Numata, Goki; Lee, Heeyoung; Hayashi, Neisei; Mizuno, Yosuke; Nakamura, Kentaro

    2017-07-01

    To date, we have developed a temperature sensor based on multimodal interference in a polymer optical fiber (POF) with an extremely high sensitivity. Here, we experimentally evaluate the influence of annealing (heat treatment) of the POF on the temperature sensitivity at room temperature. We show that the temperature sensitivity is enhanced with increasing annealing temperature, and that, by annealing the POF at 90 °C, we can achieve a temperature sensitivity of +2.17 nm/°C, which is 2.9 times larger than that without annealing (+0.75 nm/°C).

  8. Room-temperature-deposited dielectrics and superconductors for integrated photonics.

    Science.gov (United States)

    Shainline, Jeffrey M; Buckley, Sonia M; Nader, Nima; Gentry, Cale M; Cossel, Kevin C; Cleary, Justin W; Popović, Miloš; Newbury, Nathan R; Nam, Sae Woo; Mirin, Richard P

    2017-05-01

    We present an approach to fabrication and packaging of integrated photonic devices that utilizes waveguide and detector layers deposited at near-ambient temperature. All lithography is performed with a 365 nm i-line stepper, facilitating low cost and high scalability. We have shown low-loss SiN waveguides, high-Q ring resonators, critically coupled ring resonators, 50/50 beam splitters, Mach-Zehnder interferometers (MZIs) and a process-agnostic fiber packaging scheme. We have further explored the utility of this process for applications in nonlinear optics and quantum photonics. We demonstrate spectral tailoring and octave-spanning supercontinuum generation as well as the integration of superconducting nanowire single photon detectors with MZIs and channel-dropping filters. The packaging approach is suitable for operation up to 160 °C as well as below 1 K. The process is well suited for augmentation of existing foundry capabilities or as a stand-alone process.

  9. 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.

  10. Conformational variation of proteins at room temperature is not dominated by radiation damage

    International Nuclear Information System (INIS)

    Russi, Silvia; González, Ana; Kenner, Lillian R.; Keedy, Daniel A.; Fraser, James S.; Bedem, Henry van den

    2017-01-01

    Protein crystallography data collection at synchrotrons is routinely carried out at cryogenic temperatures to mitigate radiation damage. Although damage still takes place at 100 K and below, the immobilization of free radicals increases the lifetime of the crystals by approximately 100-fold. Recent studies have shown that flash-cooling decreases the heterogeneity of the conformational ensemble and can hide important functional mechanisms from observation. These discoveries have motivated increasing numbers of experiments to be carried out at room temperature. However, the trade-offs between increased risk of radiation damage and increased observation of alternative conformations at room temperature relative to cryogenic temperature have not been examined. A considerable amount of effort has previously been spent studying radiation damage at cryo-temperatures, but the relevance of these studies to room temperature diffraction is not well understood. Here, the effects of radiation damage on the conformational landscapes of three different proteins (T. danielli thaumatin, hen egg-white lysozyme and human cyclophilin A) at room (278 K) and cryogenic (100 K) temperatures are investigated. Increasingly damaged datasets were collected at each temperature, up to a maximum dose of the order of 10 7 Gy at 100 K and 10 5 Gy at 278 K. Although it was not possible to discern a clear trend between damage and multiple conformations at either temperature, it was observed that disorder, monitored by B-factor-dependent crystallographic order parameters, increased with higher absorbed dose for the three proteins at 100 K. At 278 K, however, the total increase in this disorder was only statistically significant for thaumatin. A correlation between specific radiation damage affecting side chains and the amount of disorder was not observed. Lastly, this analysis suggests that elevated conformational heterogeneity in crystal structures at room temperature is observed despite radiation

  11. Performance evaluation of ZnO–CuO hetero junction solid state room temperature ethanol sensor

    International Nuclear Information System (INIS)

    Yu, Ming-Ru; Suyambrakasam, Gobalakrishnan; Wu, Ren-Jang; Chavali, Murthy

    2012-01-01

    Graphical abstract: Sensor response (resistance) curves of time were changed from 150 ppm to 250 ppm alcohol concentration of ZnO–CuO 1:1. The response and recovery times were measured to be 62 and 83 s, respectively. The sensing material ZnO–CuO is a high potential alcohol sensor which provides a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature. Highlights: ► The main advantages of the ethanol sensor are as followings. ► Novel materials ZnO–CuO ethanol sensor. ► The optimized ZnO–CuO hetero contact system. ► A good sensor response and room working temperature (save energy). -- Abstract: A semiconductor ethanol sensor was developed using ZnO–CuO and its performance was evaluated at room temperature. Hetero-junction sensor was made of ZnO–CuO nanoparticles for sensing alcohol at room temperature. Nanoparticles were prepared by hydrothermal method and optimized with different weight ratios. Sensor characteristics were linear for the concentration range of 150–250 ppm. Composite materials of ZnO–CuO were characterized using X-ray diffraction (XRD), temperature-programmed reduction (TPR) and high-resolution transmission electron microscopy (HR-TEM). ZnO–CuO (1:1) material showed maximum sensor response (S = R air /R alcohol ) of 3.32 ± 0.1 toward 200 ppm of alcohol vapor at room temperature. The response and recovery times were measured to be 62 and 83 s, respectively. The linearity R 2 of the sensor response was 0.9026. The sensing materials ZnO–CuO (1:1) provide a simple, rapid and highly sensitive alcohol gas sensor operating at room temperature.

  12. 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)

  13. Ultrabright continuously tunable terahertz-wave generation at room temperature.

    Science.gov (United States)

    Hayashi, Shin'ichiro; Nawata, Kouji; Taira, Takunori; Shikata, Jun-ichi; Kawase, Kodo; Minamide, Hiroaki

    2014-06-05

    The hottest frequency region in terms of research currently lies in the 'frequency gap' region between microwaves and infrared: terahertz waves. Although new methods for generating terahertz radiation have been developed, most sources cannot generate high-brightness terahertz beams. Here we demonstrate the generation of ultrabright terahertz waves (brightness ~0.2 GW/sr·cm(2), brightness temperature of ~10(18) K, peak power of >50 kW) using parametric wavelength conversion in a nonlinear crystal; this is brighter than many specialized sources such as far-infrared free-electron lasers (~10(16) K, ~2 kW). We revealed novel parametric wavelength conversion using stimulated Raman scattering in LiNbO3 without stimulated Brillouin scattering using recently-developed microchip laser. Furthermore, nonlinear up-conversion techniques allow the intense terahertz waves to be visualized and their frequency determined. These results are very promising for extending applied research into the terahertz region, and we expect that this source will open up new research fields such as nonlinear optics in the terahertz region.

  14. Decoherence Assisted Single Electron Trapping at Room Temperature

    Science.gov (United States)

    Elhalawany, Ahmed; Leuenberger, Michael

    2012-02-01

    In this work, we theoretically investigate electron transport in heterostructure semiconductor nanowire (NW). We develop a new mechanism to trap an electron in a quantum dot (QD) by means of decoherence. There are six QDs in the NW. Bias voltage (Vb) is applied across the NW and gate voltage (Vg) is applied to the auxiliary QD to control single charge tunneling. The single electron dynamics along the NW is calculated by means of the generalized master equation based on the tight binding model taking into account electron LO phonon interaction (ELOPI) and thermal broadening inside the QDs. It is shown that the decoherence, which is in the pico-second (ps) regime, speeds up the trapping of the electron in the central QD with probability of 70% in less than 2 ps. Our results can be used for the implementation of high temperature single photon source (SPS) or single electron transistor (SET). We acknowledge support from NSF (Grant No. ECCS-0725514), DARPA/MTO (Grant No. HR0011-08-1-0059), NSF (Grant No. ECCS-0901784), AFOSR (Grant No. FA9550-09-1-0450), and NSF (Grant No. ECCS-1128597).

  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. Room temperature aluminum antimonide radiation detector and methods thereof

    Energy Technology Data Exchange (ETDEWEB)

    Lordi, Vincenzo; Wu, Kuang Jen J.; Aberg, Daniel; Erhart, Paul; Coombs, III, Arthur W; Sturm, Benjamin W

    2015-03-03

    In one embodiment, a method for producing a high-purity single crystal of aluminum antimonide (AlSb) includes providing a growing environment with which to grow a crystal, growing a single crystal of AlSb in the growing environment which comprises hydrogen (H.sub.2) gas to reduce oxide formation and subsequent incorporation of oxygen impurities in the crystal, and adding a controlled amount of at least one impurity to the growing environment to effectively incorporate at least one dopant into the crystal. In another embodiment, a high energy radiation detector includes a single high-purity crystal of AlSb, a supporting structure for the crystal, and logic for interpreting signals obtained from the crystal which is operable as a radiation detector at a temperature of about 25.degree. C. In one embodiment, a high-purity single crystal of AlSb includes AlSb and at least one dopant selected from a group consisting of selenium (Se), tellurium (Te), and tin (Sn).

  17. 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.

  18. Room-temperature nine-µm-wavelength photodetectors and GHz-frequency heterodyne receivers

    Science.gov (United States)

    Palaferri, Daniele; Todorov, Yanko; Bigioli, Azzurra; Mottaghizadeh, Alireza; Gacemi, Djamal; Calabrese, Allegra; Vasanelli, Angela; Li, Lianhe; Davies, A. Giles; Linfield, Edmund H.; Kapsalidis, Filippos; Beck, Mattias; Faist, Jérôme; Sirtori, Carlo

    2018-04-01

    Room-temperature operation is essential for any optoelectronics technology that aims to provide low-cost, compact systems for widespread applications. A recent technological advance in this direction is bolometric detection for thermal imaging, which has achieved relatively high sensitivity and video rates (about 60 hertz) at room temperature. However, owing to thermally induced dark current, room-temperature operation is still a great challenge for semiconductor photodetectors targeting the wavelength band between 8 and 12 micrometres, and all relevant applications, such as imaging, environmental remote sensing and laser-based free-space communication, have been realized at low temperatures. For these devices, high sensitivity and high speed have never been compatible with high-temperature operation. Here we show that a long-wavelength (nine micrometres) infrared quantum-well photodetector fabricated from a metamaterial made of sub-wavelength metallic resonators exhibits strongly enhanced performance with respect to the state of the art up to room temperature. This occurs because the photonic collection area of each resonator is much larger than its electrical area, thus substantially reducing the dark current of the device. Furthermore, we show that our photonic architecture overcomes intrinsic limitations of the material, such as the drop of the electronic drift velocity with temperature, which constrains conventional geometries at cryogenic operation. Finally, the reduced physical area of the device and its increased responsivity allow us to take advantage of the intrinsic high-frequency response of the quantum detector at room temperature. By mixing the frequencies of two quantum-cascade lasers on the detector, which acts as a heterodyne receiver, we have measured a high-frequency signal, above four gigahertz (GHz). Therefore, these wide-band uncooled detectors could benefit technologies such as high-speed (gigabits per second) multichannel coherent data

  19. Quantum confinement of zero-dimensional hybrid organic-inorganic polaritons at room temperature

    International Nuclear Information System (INIS)

    Nguyen, H. S.; Lafosse, X.; Amo, A.; Bouchoule, S.; Bloch, J.; Han, Z.; Abdel-Baki, K.; Lauret, J.-S.; Deleporte, E.

    2014-01-01

    We report on the quantum confinement of zero-dimensional polaritons in perovskite-based microcavity at room temperature. Photoluminescence of discrete polaritonic states is observed for polaritons localized in symmetric sphere-like defects which are spontaneously nucleated on the top dielectric Bragg mirror. The linewidth of these confined states is found much sharper (almost one order of magnitude) than that of photonic modes in the perovskite planar microcavity. Our results show the possibility to study organic-inorganic cavity polaritons in confined microstructure and suggest a fabrication method to realize integrated polaritonic devices operating at room temperature

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

    International Nuclear Information System (INIS)

    Owen, Robin L.; Paterson, Neil; Axford, Danny; Aishima, Jun; Schulze-Briese, Clemens; Ren, Jingshan; Fry, Elizabeth E.; Stuart, David I.; Evans, Gwyndaf

    2014-01-01

    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

  1. A Novel Spectrophotometric Method for Determination of Chloramphenicol Based On Diazotization Reaction at Room Temperature

    OpenAIRE

    Wafi, Abdul; Supriyanto, Ganden; Tjahjandarie, Tjitjik Srie

    2018-01-01

    An analytical method for determination of chloramphenicol (CAP) based on the diazotization reaction at room temperature has been developed. The CAP was reduced using zinc powder (Zn) and diazotization reaction was carried out at room temperature in the presence of NaNO2, bismuth nitrate pentahydrate (Bi(NO3)3.5H2O) as catalyst. 2-napthol was used as coupling agent to form a red-violet solution and the absorbance was measured by UV-Vis spectrophotometer at 554 nm. The optimization of analytica...

  2. CeBr3 as a room-temperature, high-resolution gamma-ray detector

    International Nuclear Information System (INIS)

    Guss, Paul; Reed, Michael; Yuan Ding; Reed, Alexis; Mukhopadhyay, Sanjoy

    2009-01-01

    Cerium bromide (CeBr 3 ) has become a material of interest in the race for high-resolution gamma-ray spectroscopy at room temperature. This investigation quantified the potential of CeBr 3 as a room-temperature, high-resolution gamma-ray detector. The performance of CeBr 3 crystals was compared to other scintillation crystals of similar dimensions and detection environments. Comparison of self-activity of CeBr 3 to cerium-doped lanthanum tribromide (LaBr 3 :Ce) was performed. Energy resolution and relative intrinsic efficiency were measured and are presented.

  3. Some problems on rf breakdown in room temperature accelerator structure, a possible criterion

    International Nuclear Information System (INIS)

    Wang, J.W.

    1986-04-01

    The discussion is confined to high gradient, room-temperature accelerators which have clean well-finished cavity surfaces and good vacuum conditions. Breakdown-initiating mechanisms due to ''cold'' field electron emission occurring at isolated sites on broad-area cavity surfaces, where the field is enhanced, are described. The influences of an alternating field and transition time tunneling are taken into account. The thermal instability resulting in vacuum voltage breakdown is hypothesized to derive a new criterion for room-temperature accelerator structure. 18 refs., 5 figs

  4. Experimental study under uniaxial cyclic behavior at room and high temperature of 316L stainless steel

    International Nuclear Information System (INIS)

    Kang Guozheng; Gao Qing; Yang Xianjie; Sun Yafang

    2001-01-01

    An experimental study was carried out of the cyclic properties of 316L stainless steel subjected to uniaxial strain and stress at room and high temperature. The effects of cyclic strain amplitude, temperature and their histories on the cyclic deformation behavior of 316L stainless steel are investigated. And, the influences of stress amplitude, mean stress, temperature and their histories on ratcheting are also analyzed. It is shown that either uniaxial cyclic property under cyclic strain or ratcheting under asymmetric uniaxial cyclic stress depends not only on the current temperature and loading state, but also on the previous temperature and loading history. Some significant results are obtained

  5. Comparison between Silicon-Carbide and diamond for fast neutron detection at room temperature

    Science.gov (United States)

    Obraztsova, O.; Ottaviani, L.; Klix, A.; Döring, T.; Palais, O.; Lyoussi, A.

    2018-01-01

    Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron yield and reactor environment. Such detector must be able to operate at high temperature (up to 600° C) and high neutron flux levels. It is worth nothing that a detector for industrial environment applications must have fast and stable response over considerable long period of use as well as high energy resolution. Silicon Carbide is one of the most attractive materials for neutron detection. Thanks to its outstanding properties, such as high displacement threshold energy (20-35 eV), wide band gap energy (3.27 eV) and high thermal conductivity (4.9 W/cm·K), SiC can operate in harsh environment (high temperature, high pressure and high radiation level) without additional cooling system. Our previous analyses reveal that SiC detectors, under irradiation and at elevated temperature, respond to neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity. The counting-rate of the thermal neutron-induced peak increases with the area of the detector, and appears to be linear with respect to the reactor power. Diamond is another semi-conductor considered as one of most promising materials for radiation detection. Diamond possesses several advantages in comparison to other semiconductors such as a wider band gap (5.5 eV), higher threshold displacement energy (40-50 eV) and thermal conductivity (22 W/cm·K), which leads to low leakage current values and make it more radiation resistant that its competitors. A comparison is proposed between these two semiconductors for the ability and efficiency to detect fast neutrons. For this purpose the deuterium-tritium neutron generator of Technical University of Dresden with 14 MeV neutron output of 1010 n·s-1 is used. In the present work, we interpret the first measurements and results with both 4H-SiC and chemical vapor deposition (CVD) diamond

  6. Comparison between Silicon-Carbide and diamond for fast neutron detection at room temperature

    Directory of Open Access Journals (Sweden)

    Obraztsova O.

    2018-01-01

    Full Text Available Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron yield and reactor environment. Such detector must be able to operate at high temperature (up to 600° C and high neutron flux levels. It is worth nothing that a detector for industrial environment applications must have fast and stable response over considerable long period of use as well as high energy resolution. Silicon Carbide is one of the most attractive materials for neutron detection. Thanks to its outstanding properties, such as high displacement threshold energy (20-35 eV, wide band gap energy (3.27 eV and high thermal conductivity (4.9 W/cm·K, SiC can operate in harsh environment (high temperature, high pressure and high radiation level without additional cooling system. Our previous analyses reveal that SiC detectors, under irradiation and at elevated temperature, respond to neutrons showing consistent counting rates as function of external reverse bias voltages and radiation intensity. The counting-rate of the thermal neutron-induced peak increases with the area of the detector, and appears to be linear with respect to the reactor power. Diamond is another semi-conductor considered as one of most promising materials for radiation detection. Diamond possesses several advantages in comparison to other semiconductors such as a wider band gap (5.5 eV, higher threshold displacement energy (40-50 eV and thermal conductivity (22 W/cm·K, which leads to low leakage current values and make it more radiation resistant that its competitors. A comparison is proposed between these two semiconductors for the ability and efficiency to detect fast neutrons. For this purpose the deuterium-tritium neutron generator of Technical University of Dresden with 14 MeV neutron output of 1010 n·s-1 is used. In the present work, we interpret the first measurements and results with both 4H-SiC and chemical vapor deposition (CVD

  7. 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.

  8. 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

  9. Instantaneous radioiodination of rose bengal at room temperature and a cold-kit therefor. [DOE patent application

    Science.gov (United States)

    O'Brien, H. Jr.; Hupf, H.B.; Wanek, P.M.

    The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free /sup 125/I/sup -/ is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

  10. Fluorescence spectroscopy of single molecules at room temperature and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Taekjip [Univ. of California, Berkeley, CA (United States)

    1996-12-01

    We performed fluorescence spectroscopy of single and pairs of dye molecules on a surface at room temperature. Near field scanning optical microscope (NSOM) and far field scanning optical microscope with multi-color excitation/detection capability were built. The instrument is capable of optical imaging with 100nm resolution and has the sensitivity necessary for single molecule detection. A variety of dynamic events which cannot be observed from an ensemble of molecules is revealed when the molecules are probed one at a time. They include (1) spectral jumps correlated with dark states, (2) individually resolved quantum jumps to and from the meta-stable triplet state, (3) rotational jumps due to desorption/readsorption events of single molecules on the surface. For these studies, a computer controlled optical system which automatically and rapidly locates and performs spectroscopic measurements on single molecules was developed. We also studied the interaction between closely spaced pairs of molecules. In particular, fluorescence resonance energy transfer between a single resonant pair of donor and acceptor molecules was measured. Photodestruction dynamics of the donor or acceptor were used to determine the presence and efficiency of energy transfer Dual molecule spectroscopy was extended to a non-resonant pair of molecules to obtain high resolution differential distance information. By combining NSOM and dual color scheme, we studied the co-localization of parasite proteins and host proteins on a human red blood cell membrane infected with malaria. These dual-molecule techniques can be used to measure distances, relative orientations, and changes in distances/orientations of biological macromolecules with very good spatial, angular and temporal resolutions, hence opening new capabilities in the study of such systems.

  11. Room-temperature negative capacitance in a ferroelectric-dielectric superlattice heterostructure

    Czech Academy of Sciences Publication Activity Database

    Gao, W.; Khan, A.; Martí, Xavier; Nelson, C.; Serrao, C.; Ravichandran, J.; Ramesh, R.; Salahuddin, S.

    2014-01-01

    Roč. 14, č. 10 (2014), s. 5814-5819 ISSN 1530-6984 Institutional support: RVO:68378271 Keywords : room-temperature negative capacitance * ferroelectrics * superlattice * epitaxial strain Subject RIV: BE - Theoretical Physics Impact factor: 13.592, year: 2014

  12. Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

    NARCIS (Netherlands)

    Venkatesan, P.; Vander Hoogerstraete, Tom; Hennebel, Tom; Binnemans, Koen; Sietsma, J.; Yang, Y.

    2018-01-01

    NdFeB magnet waste is one of the important secondary resources from which rare-earth elements (REEs) can be recovered. Herein we present an electrochemical route to selectively extract REEs from the magnet waste at room temperature. First, the magnet waste was partially leached with HCl. The

  13. 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.

  14. 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.

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

    International Nuclear Information System (INIS)

    Axford, Danny; Foadi, James; Hu, Nien-Jen; Choudhury, Hassanul Ghani; Iwata, So; Beis, Konstantinos; Evans, Gwyndaf; Alguel, Yilmaz

    2015-01-01

    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

  16. 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...

  17. 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...... into the surface structure. STS experiments are on the way to probe putative transistor-like behaviour....

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

    KAUST Repository

    Al-Jabr, Ahmad

    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.

  19. Human preference and acceptance of increased air velocity to offset warm sensation at increased room temperatures

    DEFF Research Database (Denmark)

    Cattarin, Giulio; Simone, Angela; Olesen, Bjarne W.

    Previous studies have demonstrated that in summertime increased air velocities can compensate for higher room temperatures to achieve comfortable conditions. In order to increase air movement, windows opening, ceiling or desk fans can be used at the expense of relatively low energy consumption. T...

  20. Effect of room-temperature-vulcanized silicone cure in device packaging

    Science.gov (United States)

    Wong, Ching-Ping

    This paper describes a technique for monitoring the degree of cure for room-temperature-vulcanized (RTV) silicone encapsulant systems. The method involves microdielectric measurements coupled with a time-dependent Soxhlet extraction technique. Concentrated RTV extractables recovered from Freon TA solvent are analyzed using FTIR and are further identified by GC/MS spectroscopy. As was determined by measuring the levels of extractables, cure was 90-percent complete after 16 h at room temperature. Permittivity value (dielectric constant) was found to rapidly increase (to about 2.7 from the original 2.5) during the first 30 min of room-temperature cure, with very little change afterwards. The RTV silicone was completely cured at room temperature for 3 days, with a slowly decreasing loss factor that could be detected at the very low frequency (0.01 Hz) of the measurement. Prior to the completion of the cure, unreactive OH fluids are detected in the extractables; however, when the cure is complete, only unreactive cyclics could be detected.

  1. 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...

  2. A method for electrochemical growth of homogeneous nanocrystalline ZnO thin films at room temperature

    Czech Academy of Sciences Publication Activity Database

    Pauporté, T.; Jirka, Ivan

    2009-01-01

    Roč. 54, č. 28 (2009), s. 7558-7564 ISSN 0013-4686 R&D Projects: GA AV ČR IAA400400909 Institutional research plan: CEZ:AV0Z40400503 Keywords : electrodeposition * ZnO * room temperature * photoluminiscence Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.325, year: 2009

  3. Discrepancy of room temperature ferromagnetism in Mo-doped In2O3

    Indian Academy of Sciences (India)

    standard value for instrument contribution to the peak broad- ening. Microstructure and chemical analysis were studied using Nova NanoLab field emission scanning microscope equipped with an electron dispersive X-ray spectrometer. (EDS). Magnetic-hysteresis loop measurements were ca- rried out at room temperature ...

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

    NARCIS (Netherlands)

    Xu, J.; Mojet, Barbara; van Ommen, J.G.; Lefferts, Leonardus

    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

  5. Review on numerical modeling of active magnetic regenerators for room temperature applications

    DEFF Research Database (Denmark)

    Nielsen, Kaspar Kirstein; Tusek, Jaka; Engelbrecht, Kurt

    2011-01-01

    . This paper reviews the existing numerical modeling of room temperature AMR to date. The governing equations, implementation of the magnetocaloric effect (MCE), fluid flow and magnetic field profiles, thermal conduction etc. are discussed in detail as is their impact on the AMR cycle. Flow channeling effects...

  6. Measurement of 87Rb Rydberg-state hyperfine splitting in a room-temperature vapor cell

    NARCIS (Netherlands)

    Tauschinsky, A.; Newell, R.; van Linden van den Heuvell, H.B.; Spreeuw, R.J.C.

    2013-01-01

    We present direct measurements of the hyperfine splitting of Rydberg states in 87Rb using electromagnetically induced transparency (EIT) spectroscopy in a room-temperature vapor cell. With this method, and in spite of Doppler broadening, linewidths of 3.7 MHz FWHM, i.e., significantly below the

  7. Two separable conformers of TATP and analogues exist at room temperature.

    Science.gov (United States)

    Denekamp, C; Gottlieb, L; Tamiri, T; Tsoglin, A; Shilav, R; Kapon, M

    2005-06-09

    [reaction: see text] TATP gives rise to two separable conformations because the barrier for interconversion between them is relatively high at room temperature. This kind of behavior is rare in cyclic organic systems and is the result of poor overlap in the "flip-flop" transition state. The crystal structure of the analogous tricyclohexanone triperoxide also indicates the presence of two conformers.

  8. Construction of hydrophobic wood surfaces by room temperature deposition of rutile (TiO2) nanostructures

    Science.gov (United States)

    Rongbo Zheng; Mandla A. Tshabalala; Qingyu Li; Hongyan Wang

    2015-01-01

    A convenient room temperature approach was developed for growing rutile TiO2 hierarchical structures on the wood surface by direct hydrolysis and crystallization of TiCl3 in saturated NaCl aqueous solution.The morphology and the crystal structure of TiO2 coated on the wood surface were characterized...

  9. Room temperature synthesis of crystalline Sb2S3 for SnO2 ...

    Indian Academy of Sciences (India)

    Abstract. The preparation of crystalline antimony sulphide (Sb2S3) by chemical route at room temperature was reported in this paper. The structural, morphological and optical properties of as-synthesized sample were system- atically investigated. X-ray diffraction (XRD) analysis confirms the orthorhombic crystal phase for ...

  10. 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.

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

    NARCIS (Netherlands)

    Arroyo Rodriguez, C.; Frisenda, R.; Moth-Poulsen, K.; Seldenthuis, J.S.; Bjornholm, T.; Van der Zant, H.S.

    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

  12. Non-local electrical spin injection and detection in germanium at room temperature

    Science.gov (United States)

    Rortais, F.; Vergnaud, C.; Marty, A.; Vila, L.; Attané, J.-P.; Widiez, J.; Zucchetti, C.; Bottegoni, F.; Jaffrès, H.; George, J.-M.; Jamet, M.

    2017-10-01

    Non-local carrier injection/detection schemes lie at the very foundation of information manipulation in integrated systems. This paradigm consists in controlling with an external signal the channel where charge carriers flow between a "source" and a well separated "drain." The next generation electronics may operate on the spin of carriers in addition to their charge and germanium appears as the best hosting material to develop such a platform for its compatibility with mainstream silicon technology and the predicted long electron spin lifetime at room temperature. In this letter, we demonstrate injection of pure spin currents (i.e., with no associated transport of electric charges) in germanium, combined with non-local spin detection at 10 K and room temperature. For this purpose, we used a lateral spin valve with epitaxially grown magnetic tunnel junctions as spin injector and spin detector. The non-local magnetoresistance signal is clearly visible and reaches ≈15 mΩ at room temperature. The electron spin lifetime and diffusion length are 500 ps and 1 μm, respectively, the spin injection efficiency being as high as 27%. This result paves the way for the realization of full germanium spintronic devices at room temperature.

  13. 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.

  14. Room temperature Compton profiles of conduction electrons in α-Ga ...

    Indian Academy of Sciences (India)

    B P PANDA and N C MOHAPATRA*. Department of Physics, Chikiti Mahavidyalaya, Chikiti 761 010, India. £Department of Physics, Berhampur University, Berhampur 760 007, India. Email: ncmphy123@hotmail.com. MS received 18 January 2003; accepted 21 June 2003. Abstract. Room temperature Compton profiles of ...

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

    NARCIS (Netherlands)

    Simons-Fischbein, K.; Nijmeijer, Dorothea C.; Bara, J.B.; Noble, R.D.; Wessling, Matthias

    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

  16. Cytotoxicity associated with prolonged room temperature storage of serum and proposed methods for reduction of cytotoxicity.

    Science.gov (United States)

    Shiraishi, Rikiya; Hirayama, Norio

    2015-12-01

    Canine serum preserved at room temperature (25°C) for longer than 24h is known to exhibit significant cytotoxicity. This phenomenon is one of the major reasons for the failure of virus neutralization tests. In this study, a method for reducing this cytotoxicity was investigated by applying several treatments to dog, cat and human serum prior to room temperature storage. Additionally, the identity of the cytotoxic factor generated during room temperature storage was investigated. Heat-inactivation at 56°C or 65°C and the addition of protease inhibitor prior to storage were found to be effective for reducing cytotoxicity in the serum. Furthermore, heat-inactivation at 65°C reduced the cytotoxicity that was induced under room temperature storage. Several protein factors in serum were suspected to play a role in the observed cytotoxicity. According to this study, the membrane-attack-complex in serum was not involved in the cytotoxicity. This study provides useful information for development and improvement of cell culture and virus neutralization tests. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. 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)

  18. 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

  19. Kinetics of Crystalline Iodine Dissolution in Ethanol at Room Temperature and at 60°C

    Science.gov (United States)

    Klyubin, V. V.; Klyubina, K. A.; Makovetskaya, K. N.

    2018-02-01

    The kinetics of crystalline iodine dissolution in ethanol at room temperature and 60°C is studied using the electronic absorption spectra of iodine solutions. Dissolution is shown to proceed for more than three months. It is found that the process begins with the formation of hydroiodic acid HI and is complete with the formation of I 3 - anions.

  20. Composite properties for S-2 glass in a room-temperature-curable epoxy matrix

    Science.gov (United States)

    Clements, L. L.; Moore, R. L.

    1979-01-01

    The authors have measured thermal and mechanical properties of several composites of S-2 glass fiber in a room-temperature-curable epoxy matrix. The filament-wound composites ranged from 50 to 70 vol% fiber. The composites had generally good to excellent mechanical properties, particularly in view of the moderate cost of the material. However, the composites showed rapid increases in transverse thermal expansion above 50 C, and this property must be carefully considered if any use above that temperature is contemplated.

  1. 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.

  2. Dehydrogenation of anhydrous methanol at room temperature by o-aminophenol-based photocatalysts

    OpenAIRE

    Wakizaka, Masanori; Matsumoto, Takeshi; Tanaka, Ryota; Chang, Ho-Chol

    2016-01-01

    Dehydrogenation of anhydrous methanol is of great importance, given its ubiquity as an intermediate for the production of a large number of industrial chemicals. Since dehydrogenation of methanol is an endothermic reaction, heterogeneous or homogeneous precious-metal-based catalysts and high temperatures are usually required for this reaction to proceed. Here we report the photochemical dehydrogenation of anhydrous methanol at room temperature catalysed by o-aminophenol (apH2), o-aminophenola...

  3. A room-temperature magnetic semiconductor from a ferromagnetic metallic glass

    OpenAIRE

    Liu, Wenjian; Zhang, Hongxia; Shi, Jin-an; Wang, Zhongchang; Song, Cheng; Wang, Xiangrong; Lu, Siyuan; Zhou, Xiangjun; Gu, Lin; Louzguine-Luzgin, Dmitri V.; Chen, Mingwei; Yao, Kefu; Chen, Na

    2016-01-01

    Emerging for future spintronic/electronic applications, magnetic semiconductors have stimulated intense interest due to their promises for new functionalities and device concepts. So far, the so-called diluted magnetic semiconductors attract many attentions, yet it remains challenging to increase their Curie temperatures above room temperature, particularly those based on III?V semiconductors. In contrast to the concept of doping magnetic elements into conventional semiconductors to make dilu...

  4. FAST TRACK COMMUNICATION: Reproducible room temperature giant magnetocaloric effect in Fe-Rh

    Science.gov (United States)

    Manekar, Meghmalhar; Roy, S. B.

    2008-10-01

    We present the results of magnetocaloric effect (MCE) studies in polycrystalline Fe-Rh alloy over a temperature range of 250-345 K across the first order antiferromagnetic to ferromagnetic transition. By measuring the MCE under various thermomagnetic histories, contrary to the long held belief, we show here explicitly that the giant MCE in Fe-Rh near room temperature does not vanish after the first field cycle. In spite of the fact that the virgin magnetization curve is lost after the first field cycle near room temperature, reproducibility in the MCE under multiple field cycles can be achieved by properly choosing a combination of isothermal and adiabatic field variation cycles in the field-temperature phase space. This reproducible MCE leads to a large effective refrigerant capacity of 324.42 J kg-1, which is larger than that of the well-known magnetocaloric material Gd5Si2Ge2. This information could be important as Fe-Rh has the advantage of having a working temperature of around 300 K, which can be used for room temperature magnetic refrigeration.

  5. Influence of pre-measurement thermal treatment on OSL of synthetic quartz measured at room temperature

    International Nuclear Information System (INIS)

    Kale, Y.D.; Gandhi, Y.H.

    2008-01-01

    Much effort has been made to study the influence of pre-measurement thermal treatment and ionizing radiation on quartz specimens owing to its use in a large number of applications. Optically stimulated luminescence (OSL) being a structured and sensitive phenomenon promises to correlate the responsible color center and luminescence emission. OSL studies on quartz with such conditions can reveal many significant results. The aim of the present investigation is to understand the effect of annealing temperature on OSL characteristics of synthetic quartz recorded at room temperature. At identical annealing duration and β-dose, the shape of OSL decay curve remains non-exponential; when specimens annealed at lower temperature (∼400 deg. C). The shape of decay curve changes to exponential in nature along with rise in OSL intensity when the specimen was given higher temperature of annealing (>400 deg. C). The effects of such protocol on pattern of OSL sensitivity as well as area under the OSL decay curve are also presented here. The presence of shallow traps, when OSL decay curve was recorded at room temperature seems to be responsible for the changes in OSL pattern. The influence of shallow traps is attributed to non-exponential decay of OSL recorded at room temperature

  6. 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.

  7. A Highly Selective Room Temperature NH3 Gas Sensor based on Nanocrystalline a-Fe2O3

    Directory of Open Access Journals (Sweden)

    Priyanka A. PATIL

    2017-05-01

    Full Text Available Nanocrystalline a-Fe2O3 powder was synthesized by simple, inexpensive sol-gel method. The obtained powder was calcined at 700 0C in air atmosphere for 2 hours. The structural and morphological properties of calcined powder were studied by X-ray diffraction (XRD and Field Emission Scanning Electron Microscopy (FESEM respectively. Thermal properties of dried gel were studied by Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC. The XRD pattern of the powder confirmed the a-Fe2O3 (hematite phase of iron oxide with average crystalline size of 30.87 nm calculated from Scherrer equation. The FESEM images showed uniform wormlike morphology of a-Fe2O3 powder. TGA result indicated that a-Fe2O3 is thermodynamically stable. Room temperature NH3 sensing characteristics of a-Fe2O3 were studied for various concentration levels (250-2500 ppm of NH3 at various humid conditions. The sensor based on a-Fe2O3 exhibited good selectivity and excellent sensitivity (S=92 towards 1000 ppm of NH3 with quick response of 4 sec and fast recovery of 9 sec. Room temperature sensing mechanism is also discussed.

  8. Room temperature strong light-matter coupling in three dimensional terahertz meta-atoms

    Energy Technology Data Exchange (ETDEWEB)

    Paulillo, B., E-mail: bruno.paulillo@u-psud.fr; Manceau, J.-M., E-mail: jean-michel.manceau@u-psud.fr; Colombelli, R., E-mail: raffaele.colombelli@u-psud.fr [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France); Li, L. H.; Davies, A. G.; Linfield, E. H. [School of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom)

    2016-03-07

    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 (2Ω{sub Rabi}), amounts to 20% of the bare transition at room temperature, and it increases to 28% at low-temperature.

  9. Defect controlled room temperature ferromagnetism in Co-doped barium titanate nanocrystals

    International Nuclear Information System (INIS)

    Ray, Sugata; Kolen'ko, Yury V; Watanabe, Tomoaki; Yoshimura, Masahiro; Itoh, Mitsuru; Kovnir, Kirill A; Lebedev, Oleg I; Turner, Stuart; Erni, Rolf; Tendeloo, Gustaaf Van; Chakraborty, Tanushree

    2012-01-01

    Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the central feature of this work. Here, we report the development of room temperature ferromagnetism in nanosized Co-doped barium titanate particles with a size of around 14 nm, synthesized by a solvothermal drying method. A combination of x-ray diffraction with state-of-the-art electron microscopy techniques confirms the intrinsic doping of Co into BaTiO 3 . The development of the room temperature ferromagnetism was tracked down to the different donor defects, namely hydroxyl groups at the oxygen site and oxygen vacancies and their relative concentrations at the surface and the core of the nanocrystal, which could be controlled by post-synthesis drying and thermal treatments.

  10. Simulating the room-temperature dynamic motion of a ferromagnetic vortex in a bistable potential

    Science.gov (United States)

    Haber, E.; Badea, R.; Berezovsky, J.

    2018-05-01

    The ability to precisely and reliably control the dynamics of ferromagnetic (FM) vortices could lead to novel nonvolatile memory devices and logic gates. Intrinsic and fabricated defects in the FM material can pin vortices and complicate the dynamics. Here, we simulated switching a vortex between bistable pinning sites using magnetic field pulses. The dynamic motion was modeled with the Thiele equation for a massless, rigid vortex subject to room-temperature thermal noise. The dynamics were explored both when the system was at zero temperature and at room-temperature. The probability of switching for different pulses was calculated, and the major features are explained using the basins of attraction map of the two pinning sites.

  11. 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.

  12. Defect controlled room temperature ferromagnetism in Co-doped barium titanate nanocrystals.

    Science.gov (United States)

    Ray, Sugata; Kolen'ko, Yury V; Kovnir, Kirill A; Lebedev, Oleg I; Turner, Stuart; Chakraborty, Tanushree; Erni, Rolf; Watanabe, Tomoaki; Van Tendeloo, Gustaaf; Yoshimura, Masahiro; Itoh, Mitsuru

    2012-01-20

    Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the central feature of this work. Here, we report the development of room temperature ferromagnetism in nanosized Co-doped barium titanate particles with a size of around 14 nm, synthesized by a solvothermal drying method. A combination of x-ray diffraction with state-of-the-art electron microscopy techniques confirms the intrinsic doping of Co into BaTiO3. The development of the room temperature ferromagnetism was tracked down to the different donor defects, namely hydroxyl groups at the oxygen site (OH·(O) and oxygen vacancies (V··(O), and their relative concentrations at the surface and the core of the nanocrystal, which could be controlled by post-synthesis drying and thermal treatments.

  13. Room temperature thin foil SLIM-cut using an epoxy paste: experimental versus theoretical results

    International Nuclear Information System (INIS)

    Bellanger, Pierre; Serra, Joao; Bouchard, Pierre-Olivier; Bernacki, Marc

    2015-01-01

    The stress induced lift-off method (SLIM) -cut technique allows the detachment of thin silicon foils using a stress inducing layer. In this work, results of SLIM-cut foils obtained using an epoxy stress inducing layer at room temperature are presented. Numerical analyses were performed in order to study and ascertain the important experimental parameters. The experimental and simulation results are in good agreement. Indeed, large area (5 × 5 cm 2 ) foils were successfully detached at room temperature using an epoxy thickness of 900 μm and a curing temperature of 150 °C. Moreover, three foils (5 × 3 cm 2 ) with thickness 135, 121 and 110 μm were detached from the same monocrystalline substrate. Effective minority carrier lifetimes of 46, 25 and 20 μs were measured using quasi-steady-state photoconductance technique in these foils after iodine ethanol surface passivation. (paper)

  14. Room temperature self-assembly of mixed nanoparticles into photonic structures.

    Science.gov (United States)

    Naqshbandi, Masood; Canning, John; Gibson, Brant C; Nash, Melissa M; Crossley, Maxwell J

    2012-01-01

    Manufacturing complex composites and structures using incompatible materials is central to next-generation technologies. In photonics, silica offers passivity, low loss and robustness, making it the ideal material platform for optical transport. However, these properties partly stem from the high-temperature processing conditions necessary for silica waveguide fabrication, restricting the functionalisation of waveguides to robust inorganic dopants. This means for many sensor and active device applications, large numbers of materials are excluded. These include many organic and carbon systems such as dyes and diamond. Here we propose using intermolecular forces to bind nanoparticles together at room temperature and demonstrate the room-temperature self-assembly of long microwires (length ~7 cm, width ~10 μm) with and without rhodamine B. Further we report on mixed self-assembly of silica and single-photon-emitting nitrogen-vacancy-containing diamond nanoparticles, opening up a new direction in material science.

  15. 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 velocit...... decay and the shape of velocity and temperature profiles in front of the inlet device by traditional jet theory, by stratified flow theory or by a combination of the two theories.......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...

  16. High fluence proton irradiation of GaAs detectors at room temperature and at -8 C

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, W.J.; Albertz, D.; Braunschweig, W.; Chu, Z.; Karpinski, W.; Krais, R.; Kubicki, T.; Luebelsmeyer, K.; Rente, C.; Syben, O.; Tenbusch, F.; Toporowski, M. [Technische Hochschule Aachen (Germany). 1. Physikalisches Inst.

    1998-02-01

    Semi-insulating GaAs detectors processed in Aachen using Freiberger compound material with low carbon content (FCM-LC) have been irradiated with protons (23 GeV) at eleven different fluences up to 6.3 x 10{sup 14} p/cm{sup 2} at room temperature. The detectors have been characterized in terms of macroscopic quantities like I-V characteristic curves and the signal response for incident minimum ionizing particles before and after irradiation. At the temperature of -8 C three other GaAs detectors have been irradiated with protons at fluences of about 6 x 10{sup 13} p/cm{sup 2}. After the irradiation they are warmed up at room temperature. The behaviour of the detectors before and after the warming up period has been studied. (orig.). 8 refs.

  17. Thermoelectric Power Generation from Lanthanum Strontium Titanium Oxide at Room Temperature through the Addition of Graphene.

    Science.gov (United States)

    Lin, Yue; Norman, Colin; Srivastava, Deepanshu; Azough, Feridoon; Wang, Li; Robbins, Mark; Simpson, Kevin; Freer, Robert; Kinloch, Ian A

    2015-07-29

    The applications of strontium titanium oxide based thermoelectric materials are currently limited by their high operating temperatures of >700 °C. Herein, we show that the thermal operating window of lanthanum strontium titanium oxide (LSTO) can be reduced to room temperature by the addition of a small amount of graphene. This increase in operating performance will enable future applications such as generators in vehicles and other sectors. The LSTO composites incorporated one percent or less of graphene and were sintered under an argon/hydrogen atmosphere. The resultant materials were reduced and possessed a multiphase structure with nanosized grains. The thermal conductivity of the nanocomposites decreased upon the addition of graphene, whereas the electrical conductivity and power factor both increased significantly. These factors, together with a moderate Seebeck coefficient, meant that a high power factor of ∼2500 μWm(-1)K(-2) was reached at room temperature at a loading of 0.6 wt % graphene. The highest thermoelectric figure of merit (ZT) was achieved when 0.6 wt % graphene was added (ZT = 0.42 at room temperature and 0.36 at 750 °C), with >280% enhancement compared to that of pure LSTO. A preliminary 7-couple device was produced using bismuth strontium cobalt oxide/graphene-LSTO pucks. This device had a Seebeck coefficient of ∼1500 μV/K and an open voltage of 600 mV at a mean temperature of 219 °C.

  18. Ratchetting behavior of type 304 stainless steel at room and elevated temperatures

    International Nuclear Information System (INIS)

    Ruggles, M.; Krempl, E.

    1988-01-01

    The zero-to-tension ratchetting behavior was investigated under uniaxial loading at room temperature and at 550, 600 and 650/degree/ C. In History I the maximum stress level of ratchetting was equal to the stress reached in a tensile test at one percent strain. For History II the maximum stress level was established as the stress reached after a 2100 s relaxation at one percent strain. Significant ratchetting was observed for History I at room temperature but not at the elevated temperatures. The accumulated ratchet strain increases with decreasing stress rate. Independent of the stress rates used insignificant ratchet strain was observed at room temperature for History II. This observation is explained in the context of the viscoplasticity theory based on overstress by the exhaustion of the viscous contribution to the stress during relaxation. The viscous part of the stress is the driving force for the ratchetting in History I. Strain aging is presumably responsible for the lack of short-time inelastic deformation resulting in a nearly rate-independent behavior at the elevated temperatures. 26 refs., 7 figs., 1 tab

  19. Improvement of Superplasticity in High-Mg Aluminum Alloys by Sacrifice of Some Room Temperature Formability

    Science.gov (United States)

    Jin, H.; Amirkhiz, B. Shalchi; Lloyd, D. J.

    2018-03-01

    The mechanical properties of fully annealed Al-4.6 wt pct Mg alloys with different levels of Mn and Fe have been characterized at room and superplastic forming (SPF) temperatures. The effects of Mn and Fe on the intermetallic phase, grain structure, and cavitation were investigated and correlated to the formability at different temperatures. Although both Mn and Fe contribute to the formation of Al6(Mn,Fe) phase, which refines the grain structure by particle-stimulated nucleation and Zener pinning, their effects are different. An increasing Mn reduces the room temperature formability due to the increasing number of intermetallic particles, but significantly improves the superplasticity by fine grain size-induced grain boundary sliding. Meanwhile, the Fe makes the constituent particles very coarse, resulting in reduced formability at all temperatures due to extensive cavitation. A combination of high Mn and low Fe is therefore beneficial to SPF, while low levels of both elements are good for cold forming. Consequently, the superplasticity of high-Mg aluminum alloys can be significantly improved by modifying the chemical composition with sacrifice of some room temperature formability.

  20. Design optimization for main control room temperature and humidity control of digital nuclear power plant

    International Nuclear Information System (INIS)

    Chen Yujuan; Mao Hongwei; Liu Dongbo; Chen Donglei

    2014-01-01

    The main control room (MCR) temperature and humidity control system of nuclear power plant has major capacity lag and some interference factors. In order to meet the human factor requirements of MCR's operators and the control panels' environmental requirements, the improved temperature and humidity control scheme was designed based on the provided temperature cascade control system and the humidity cascade control system. In order to overcome the PID controller's shortcoming heavily depending on the accurate mathematical model, an intelligent PID parameter setting method was provided with the improved particle swarm optimization (PSO) algorithm. (authors)

  1. Room temperature ferromagnetism in thermally diffused Cr in GaN

    Science.gov (United States)

    Suggisetti, P.; Banerjee, D.; Adari, R.; Pande, N.; Patil, T.; Ganguly, S.; Saha, D.

    2013-03-01

    We report room temperature ferromagnetism in crystalline GaCrN prepared by Cr deposition and drive-in diffusion with Curie temperature much above 300 K. The Curie temperature increases with increasing active Cr concentration. Cr doped GaN acts as an n-type material with significant increase in electron carrier concentration due to the presence of Cr. Optical property of GaCrN is found to be very similar to GaN with an additional peak at 3.29 eV due to Cr. The hysteresis measurements show that the ferromagnetic ordering is maintained up to 300 K with no significant change in saturation magnetization.

  2. Full conformational landscape of 3-Methoxyphenol revealed by room temperature mm-wave rotational spectroscopy supported by quantum chemical calculations.

    Science.gov (United States)

    Roucou, Anthony; Fontanari, Daniele; Dhont, Guillaume; Jabri, Atef; Bray, Cédric; Hindle, Francis; Mouret, Gaël; Bocquet, Robin; Cuisset, Arnaud

    2018-03-30

    Room temperature millimeter-wave rotational spectroscopy supported by high level of theory calculations have been employed to fully characterise the conformational landscape of 3-Methoxyphenol, a semi-volatile polar oxygenated aromatic compound precursor of secondary organic aerosols in the atmosphere arising from biomass combustion. While previous rotationally-resolved spectroscopic studies in the microwave and in the UV domains failed to observe the complete conformational landscape, the 70 - 330 GHz rotational spectrum measured in this study reveals the ground state rotational signatures of the four stable conformations theoretically predicted. Moreover, rotational transitions in the lowest energy vibrationally excited states were assigned for two conformers. While the inertial defect of methoxyphenol does not signicantly change between conformers and isomers, the excitation of the methoxy out-of-plane bending is the main contribution to the non-planarity of the molecule. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Platinum thin film resistors as accurate and stable temperature sensors

    Science.gov (United States)

    Diehl, W.

    1984-01-01

    The measurement characteristics of thin-Pt-film temperature sensors fabricated using advanced methods are discussed. The limitations of wound-wire Pt temperature sensors and the history of Pt-film development are outlined, and the commonly used film-deposition, structuring, and trimming methods are presented in a table. The development of a family of sputtered film resistors is described in detail and illustrated with photographs of the different types. The most commonly used tolerances are reported as + or - 0.3 C + 0.5 percent of the temperature measured.

  4. Low radiation level detection with room temperature InAs detector

    Science.gov (United States)

    Makai, Janos P.; Makai, Tamas

    2014-08-01

    Recently, room temperature or near room temperature InAs detectors are widely used in laser warning receivers, process control monitors, temperature sensors, etc. requiring linear operation over many decades of the sensitivity range. The linearity of zero biased Si, InGaAs and Ge detectors is thoroughly discussed in the literature, contrary to InAs detectors. In an earlier work of the authors it has been demonstrated that applying a bootstrap circuit to a Ge detector - depending on the frequency of the operation - will virtually increase the shunt resistance of the detector by 3-6 decades compared to the detector alone. In the present work, a similar circuitry was applied to a room temperature InAs detector, the differences between the bootstrapped Ge and bootstrapped InAs detector are underlined. It is shown, how the bootstrap circuit channels the photogenerated current to the feedback impedance decreasing with many decades the detectable low level limit of the detector - I/V converter unit. The linearity improvement results are discussed as a function of the chopping frequency, calculated and measured values are compared, the noise sources are analyzed and noise measurement results are presented.

  5. Predicting the thermal conductivity of aluminium alloys in the cryogenic to room temperature range

    Science.gov (United States)

    Woodcraft, Adam L.

    2005-06-01

    Aluminium alloys are being used increasingly in cryogenic systems. However, cryogenic thermal conductivity measurements have been made on only a few of the many types in general use. This paper describes a method of predicting the thermal conductivity of any aluminium alloy between the superconducting transition temperature (approximately 1 K) and room temperature, based on a measurement of the thermal conductivity or electrical resistivity at a single temperature. Where predictions are based on low temperature measurements (approximately 4 K and below), the accuracy is generally better than 10%. Useful predictions can also be made from room temperature measurements for most alloys, but with reduced accuracy. This method permits aluminium alloys to be used in situations where the thermal conductivity is important without having to make (or find) direct measurements over the entire temperature range of interest. There is therefore greater scope to choose alloys based on mechanical properties and availability, rather than on whether cryogenic thermal conductivity measurements have been made. Recommended thermal conductivity values are presented for aluminium 6082 (based on a new measurement), and for 1000 series, and types 2014, 2024, 2219, 3003, 5052, 5083, 5086, 5154, 6061, 6063, 6082, 7039 and 7075 (based on low temperature measurements in the literature).

  6. 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 (< 50 fs) 9 keV 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

  7. High Temperature Stable Nanocrystalline SiGe Thermoelectric Material

    Science.gov (United States)

    Yang, Sherwin (Inventor); Matejczyk, Daniel Edward (Inventor); Determan, William (Inventor)

    2013-01-01

    A method of forming a nanocomposite thermoelectric material having microstructural stability at temperatures greater than 1000 C. The method includes creating nanocrystalline powder by cryomilling. The method is particularly useful in forming SiGe alloy powder.

  8. General incorporation of diverse components inside metal-organic framework thin films at room temperature

    Science.gov (United States)

    Mao, Yiyin; Li, Junwei; Cao, Wei; Ying, Yulong; Hu, Pan; Liu, Yu; Sun, Luwei; Wang, Hongtao; Jin, Chuanhong; Peng, Xinsheng

    2014-11-01

    Porous metal-organic frameworks (MOFs) demonstrate great potential for numerous applications. Although hetero-functional components have been encapsulated within MOF crystalline particles, the uniform incorporation of functional species with different sizes, shapes and functions in MOF thin films with dual properties, especially at room temperature and without the degradation of the MOF framework, remains a significant challenge towards further enriching their functions for various purposes. Here we report a general method that can rapidly encapsulate diverse functional components, including small ions, micrometre-sized particles, inorganic nanoparticles and bioactive proteins, in MOF thin films at room temperature via a metal-hydroxide-nanostrand-assisted confinement technique. These functional component-encapsulated MOF composite thin films exhibit synergistic and size-selective catalytic, bio-electrochemical, conductive and flexible functionalities that are desirable for thin film devices, including catalytic membrane reactors, biosensors and flexible electronic devices.

  9. 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.

  10. Surface activated room-temperature bonding in Ar gas ambient for MEMS encapsulation

    Science.gov (United States)

    Takagi, Hideki; Kurashima, Yuichi; Takamizawa, Akifumi; Ikegami, Takeshi; Yanagimachi, Shinya

    2018-02-01

    Surface activated room-temperature bonding of Si and sapphire wafers in high-purity inert gas ambient was examined. Although surface activated bonding has been mainly performed in high vacuum, Si and sapphire wafers were successfully bonded in Ar gas ambient up to 90 kPa, which is almost atmospheric pressure. The dicing test proved that the bonding prepared in Ar gas ambient was strong enough for MEMS packaging, although the bonding strength was slightly decreased compared with that prepared in vacuum. Transmission electron microscope observation revealed that the bonding interface prepared in Ar gas ambient is almost the same as that prepared in vacuum. It means that Ar atoms in the bonding ambient do not hamper the interatomic bond formation at the bonding interface. Room-temperature bonding in gas ambient enables hermetic packaging of MEMS devices, such as inertia sensors, MEMS switches, and Cs vapor cells for MEMS atomic clocks at various pressures.

  11. 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.

  12. Room-temperature deposition of crystalline patterned ZnO films by confined dewetting lithography

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda-Guzman, S., E-mail: selene.sepulvedagz@uanl.edu.mx [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia. UANL, PIIT Monterrey, CP 66629, Apodaca NL (Mexico); Reeja-Jayan, B. [Texas Materials Institute, University of Texas at Austin, Austin, TX 78712 (United States); De la Rosa, E. [Centro de Investigacion en Optica, Loma del Bosque 115 Col. Lomas del Campestre C.P. 37150 Leon, Gto. Mexico (Mexico); Ortiz-Mendez, U. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia. UANL, PIIT Monterrey, CP 66629, Apodaca NL (Mexico); Reyes-Betanzo, C. [Instituto Nacional de Astrofisica Optica y Electronica, Calle Luis Enrique Erro No. 1, Santa Maria Tonanzintla, Puebla. Apdo. Postal 51 y 216, C.P. 72000 Puebla (Mexico); Cruz-Silva, R. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, UAEM. Av. Universidad 1001, Col. Chamilpa, CP 62210 Cuernavaca, Mor. (Mexico); Jose-Yacaman, M. [Physics and Astronomy Department University of Texas at San Antonio 1604 campus San Antonio, TX 78249 (United States)

    2010-03-15

    In this work patterned ZnO films were prepared at room-temperature by deposition of {approx}5 nm size ZnO nanoparticles using confined dewetting lithography, a process which induces their assembly, by drying a drop of ZnO colloidal dispersion between a floating template and the substrate. Crystalline ZnO nanoparticles exhibit a strong visible (525 nm) light emission upon UV excitation ({lambda} = 350 nm). The resulting films were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM). The method described herein presents a simple and low cost method to prepare crystalline ZnO films with geometric patterns without additional annealing. Such transparent conducting films are attractive for applications like light emitting diodes (LEDs). As the process is carried out at room temperature, the patterned crystalline ZnO films can even be deposited on flexible substrates.

  13. Nickel in silicon: Room-temperature in-diffusion and interaction with radiation defects

    Energy Technology Data Exchange (ETDEWEB)

    Yarykin, Nikolai [Institute of Microelectronics Technology, RAS, Chernogolovka (Russian Federation); Weber, Joerg [Technische Universitaet Dresden (Germany)

    2017-07-15

    Nickel is incorporated into silicon wafers during chemomechanical polishing in an alkaline Ni-contaminated slurry at room temperature. The nickel in-diffusion is detected by DLTS depth profiles of a novel Ni{sub 183} level, which is formed due to a reaction between the diffusing nickel and the VO centers introduced before the polishing. The Ni{sub 183} profile extends up to 10 μm after a 2 min polishing. The available data provide a lower estimate for the room-temperature nickel diffusivity D{sub Ni} > 10{sup -9} cm{sup 2} s{sup -1}. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Wet chemically grown composite thin film for room temperature LPG sensor

    Science.gov (United States)

    Birajadar, Ravikiran; Desale, Dipalee; Shaikh, Shaheed; Mahajan, Sandip; Upadhye, Deepak; Ghule, Anil; Sharma, Ramphal

    2014-04-01

    We have synthesized thin film of zinc oxide-polyaniline (ZnO/PANI) composite using a simple wet chemical approach. As-synthesized ZnO/PANI composite thin film studied using different characterization techniques. The optical study reveals the penetration and interaction of PANI molecules with ZnO thin film. Prominent blue shift in UV-vis due to interaction between ZnO and PANI indicate presence of zinc oxide in polyaniline matrix. It is observed that ZnO thin film is not sensitive to LPG (liquefied petroleum gas) at room temperature. On the other hand ZnO/PANI composite thin film shows good response and recovery behaviors at room temperature.

  15. 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...

  16. Physicochemical, spectroscopic and electrochemical characterization of magnesium ion-conducting, room temperature, ternary molten electrolytes

    Science.gov (United States)

    Narayanan, N. S. Venkata; Ashok Raj, B. V.; Sampath, S.

    Room temperature, magnesium ion-conducting molten electrolytes are prepared using a combination of acetamide, urea and magnesium triflate or magnesium perchlorate. The molten liquids show high ionic conductivity, of the order of mS cm -1 at 298 K. Vibrational spectroscopic studies based on triflate/perchlorate bands reveal that the free ion concentration is higher than that of ion-pairs and aggregates in the melt. Electrochemical reversibility of magnesium deposition and dissolution is demonstrated using cyclic voltammetry and impedance studies. The transport number of Mg 2+ ion determined by means of a combination of d.c. and a.c. techniques is ∼0.40. Preliminary studies on the battery characteristics reveal good capacity for the magnesium rechargeable cell and open up the possibility of using this unique class of acetamide-based room temperature molten electrolytes in secondary magnesium batteries.

  17. 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.

  18. Optimization of contact conditions between iron base alloys and mercury at room temperature

    International Nuclear Information System (INIS)

    Medina-Almazan, L.; Rouchaud, J.-C.; Auger, T.; Gorse, D.

    2008-01-01

    The intimate contact or wetting of iron-base alloys by mercury is obtained at room temperature by varying the environmental conditions, quasi immediately for Armco iron and a high purity Fe-25Ni alloy, after ∼30 min of contact for the 316L/Hg couple, after one week of contact for the T91/Hg couple. Careful mechanical polishing allows for wetting the notches of CCT specimens made in T91 steel with Hg, whereas chemical etching in 4%HCl is required to wet 316L SS identical specimens. Using ICP-OES measurements, values of solubility limit are given for both Fe (45.5 ± 0.4 wt ppm) and Cr (0.56 ± 0.07 wt ppm) in mercury at room temperature, the one of nickel (2.6 ± 0.39 wt ppm) being in agreement with the literature data

  19. Optimization of contact conditions between iron base alloys and mercury at room temperature

    Science.gov (United States)

    Medina-Almazán, L.; Rouchaud, J.-C.; Auger, T.; Gorse, D.

    2008-03-01

    The intimate contact or wetting of iron-base alloys by mercury is obtained at room temperature by varying the environmental conditions, quasi immediately for Armco iron and a high purity Fe-25Ni alloy, after ˜30 min of contact for the 316L/Hg couple, after one week of contact for the T91/Hg couple. Careful mechanical polishing allows for wetting the notches of CCT specimens made in T91 steel with Hg, whereas chemical etching in 4%HCl is required to wet 316L SS identical specimens. Using ICP-OES measurements, values of solubility limit are given for both Fe (45.5 ± 0.4 wt ppm) and Cr (0.56 ± 0.07 wt ppm) in mercury at room temperature, the one of nickel (2.6 ± 0.39 wt ppm) being in agreement with the literature data.

  20. A Two-Dimensional Manganese Gallium Nitride Surface Structure Showing Ferromagnetism at Room Temperature.

    Science.gov (United States)

    Ma, Yingqiao; Chinchore, Abhijit V; Smith, Arthur R; Barral, María Andrea; Ferrari, Valeria

    2018-01-10

    Practical applications of semiconductor spintronic devices necessitate ferromagnetic behavior at or above room temperature. In this paper, we demonstrate a two-dimensional manganese gallium nitride surface structure (MnGaN-2D) which is atomically thin and shows ferromagnetic domain structure at room temperature as measured by spin-resolved scanning tunneling microscopy and spectroscopy. Application of small magnetic fields proves that the observed magnetic domains follow a hysteretic behavior. Two initially oppositely oriented MnGaN-2D domains are rotated into alignment with only 120 mT and remain mostly in alignment at remanence. The measurements are further supported by first-principles theoretical calculations which reveal highly spin-polarized and spin-split surface states with spin polarization of up to 95% for manganese local density of states.

  1. Heavy metal ternary halides for room-temperature x-ray and gamma-ray detection

    Science.gov (United States)

    Liu, Zhifu; Peters, John A.; Stoumpos, Constantinos C.; Sebastian, Maria; Wessels, Bruce W.; Im, Jino; Freeman, Arthur J.; Kanatzidis, Mercouri G.

    2013-09-01

    We report our recent progress on wide bandgap ternary halide compounds CsPbBr3 and CsPbCl3 for room temperature x-ray and gamma-ray detectors. Their bandgaps are measured to be 2.24 eV and 2.86 eV, respectively. The measured mobility-lifetime products of CsPbBr3 are 1.7×10-3, 1.3×10-3 cm2/V, for electron and hole carriers, respectively, comparable to those of CdTe. We measured the room temperature spectral response of CsPbBr3 sample to Ag x-ray radiation. It has a well-resolved spectral response to the 22.4 keV Kα radiation peak and detector efficiency comparable to that of CdZnTe detector at 295 K.

  2. Room and elevated temperature Mechanical Behavior of 9-12% Cr Steels

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, Omer N.; Hawk, Jeffrey A.; Schrems, Karol K.

    2005-02-01

    The mechanical properties of medium Cr steels used in fossil fired power plants are very good because of their excellent high temperature microstructural stability. However, as the desire to increase the operating temperature (>650C) of the plant goes up, the need for steels that maintain their strength at these temperatures also increases. The mechanical properties of three medium Cr steels (0.08C-(9-12)Cr-1.2Ni-0.7Mo-3.0Cu-3.0Co-0.5Ti) were investigated through hardness, hot hardness and tensile measurements. The strength of the 9-12%Cr steels at room temperature after long-term isothermal aging (750C; 1000 hours) compares favorably with that of other power plant steels (e.g., P91). In addition, the elevated temperature strength and hot hardness also behave similarly. The mechanical behavior will be discussed in terms of the strength, elongation and tensile fracture characteristics.

  3. 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...... tested on field data from a PCB remediation case in an apartment in another contaminated building complex where PCB concentrations and temperature were measured simultaneously and regularly throughout one year. The model fitted relatively well with the regression of measured PCB air concentrations, ln...... 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...

  4. 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.

  5. 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.

  6. From molten salts to room temperature ionic liquids: Simulation studies on chloroaluminate systems

    OpenAIRE

    Salanne, Mathieu; Siqueira, Leonardo J. A.; Seitsonen, Ari P.; Madden, Paul A.; Kirchner, Barbara

    2013-01-01

    International audience; An interaction potential including chloride anion polarization effects, constructed from first-principles calculations, is used to examine the structure and transport properties of a series of chloroaluminate melts. A particular emphasis was given to the study of the equimolar mixture of aluminium chloride with 1-ethyl-3-methylimidazolium chloride, which forms a room temperature ionic liquid EMI-AlCl 4. The structure yielded by the classical simulations performed withi...

  7. 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.

  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. Towards Molecular Dynamics Simulations of Chiral Room-Temperature Ionic Liquids

    Czech Academy of Sciences Publication Activity Database

    Lísal, Martin; Chval, Z.; Storch, Jan; Izák, Pavel

    2014-01-01

    Roč. 189, SI (2014), s. 85-94 ISSN 0167-7322 R&D Projects: GA ČR(CZ) GAP106/12/0569; GA MŠk LH12020 Institutional support: RVO:67985858 Keywords : chiral room-temperature ionic liquid * molecular dynamics simulation * non-polarizable fully flexible all-atom force field Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.515, year: 2014

  10. Two-Dimensional Metrology with Flatbed Scanners at Room and Liquid Nitrogen Temperatures

    International Nuclear Information System (INIS)

    Grau Carles, A.; Grau Malonda, A.

    2000-01-01

    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

  11. Room-temperature Cu-catalyzed N-arylation of aliphatic amines in neat water.

    Science.gov (United States)

    Wang, Deping; Zheng, Yanwen; Yang, Min; Zhang, Fuxing; Mao, Fangfang; Yu, Jiangxi; Xia, Xiaohong

    2017-10-04

    A room-temperature and PTC-free copper-catalyzed N-arylation of aliphatic amines in neat water has been developed. Using a combination of CuI and 6,7-dihydroquinolin-8(5H)-one oxime as the catalyst and KOH as the base, a wide range of aliphatic amines are arylated with various aryl and heteroaryl halides to give the corresponding products in up to 95% yield.

  12. Establishment of a room temperature molten salt capability to measure fundamental thermodynamic properties of actinide elements

    International Nuclear Information System (INIS)

    Smith, W.H.; Costa, D.A.

    1998-01-01

    This is the final report of a six-month, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The goal of this work was to establish a capability for the measurement of fundamental thermodynamic properties of actinide elements in room temperature molten salts. This capability will be used to study in detail the actinide chloro- and oxo- coordination chemistries that dominate in the chloride-based molten salt media. Uranium will be the first actinide element under investigation

  13. BF3/nano-γ-Al2O3 Promoted Knoevenagel Condensation at Room Temperature

    Directory of Open Access Journals (Sweden)

    B. F. Mirjalili

    2015-10-01

    Full Text Available The Knoevenagel condensation of aromatic aldehydes with barbituric acid, dimedone and malononitrile occurred in the presence of BF3/nano-γ-Al2O3 at room temperature in ethanol. This catalyst is characterized by powder X-ray diffraction (XRD, fourier transform infrared spectroscopy (FT-IR, thermal gravimetric analysis (TGA, field emission scanning electron microscopy (FESEM and energy-dispersive X-ray spectroscopy (EDS.

  14. Microstructure and mechanical properties of Al-xMg alloys processed by room temperature ECAP

    OpenAIRE

    Chen, Yongjun; Chai, YC; Roven, Hans Jørgen; Subbarayan, Sapthagireesh; Yu, Yingda; Hjelen, Jarle

    2012-01-01

    Microstructure development and mechanical properties of Al–xMg alloys (x = 0, 1, 5–10 wt%), processed by ECAP at room temperature, have been investigated. The results show that the microstructures of Al–xMg alloys are refined by the interaction of shear bands and their increase in number during ECAP. The addition of magnesium to aluminum promotes the grain refinement. Misorientation increase induced by particles along grain boundaries is observed by using high resolution EBSD. As ECAP strain ...

  15. Research on cw electron accelerators using room-temperature rf structures: Annual report

    International Nuclear Information System (INIS)

    1986-01-01

    This joint NBS-Los Alamos project of ''Research on CW Electron Accelerators Using Room-Temperature RF Structures'' began seven years ago with the goal of developing a technology base for cw electron accelerators. In this report we describe our progress during FY 1986 and present our plans for completion of the project. First, however, it is appropriate to review the past contributions of the project, describe its status, and indicate its future benefits

  16. Strength evaluation test of pressureless-sintered silicon nitride at room temperature

    Science.gov (United States)

    Matsusue, K.; Takahara, K.; Hashimoto, R.

    1984-01-01

    In order to study strength characteristics at room temperature and the strength evaluating method of ceramic materials, the following tests were conducted on pressureless sintered silicon nitride specimens: bending tests, the three tensile tests of rectangular plates, holed plates, and notched plates, and spin tests of centrally holed disks. The relationship between the mean strength of specimens and the effective volume of specimens are examined using Weibull's theory. The effect of surface grinding on the strength of specimens is discussed.

  17. 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. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Neutron in-beam Moessbauer spectroscopic study of iron disulfide at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, M. K. [International Christian University, College of Liberal Arts (Japan); Kobayashi, Y., E-mail: kyoshio@riken.jp [RIKEN (Japan); Nonaka, H.; Yamada, Y. [Science University of Tokyo, Department of Chemistry (Japan); Sakai, Y. [Daido Institute of Technology (Japan); Shoji, H. [Tokyo Metropolitan University, Graduate School of Science (Japan); Matsue, H. [Japan Atomic Energy Research Institute (Japan)

    2005-11-15

    An in-beam emission Moessbauer spectrum of {sup 57}Fe arising from the {sup 56}Fe(n, {gamma}) {sup 57}Fe reaction in iron disulfide at room temperature was measured with a parallel plate avalanche counter. It was clearly observed that the nuclear reaction and the following process lead to the production of a new chemical species of iron different from the parent compound.

  19. Materials for spintronic: Room temperature ferromagnetism in Zn-Mn-O interfaces

    International Nuclear Information System (INIS)

    Quesada, A.; Garcia, M.A.; Crespo, P.; Hernando, A.

    2006-01-01

    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 3+ and Mn +4 in MnO 2 grains where diffusion of Zn promotes the Mn 4+→ Mn 3+ reduction. Potential uses of this material in spintronic devices are analysed

  20. 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.

  1. Ultrasonic acoustic levitation for fast frame rate X-ray protein crystallography at room temperature

    OpenAIRE

    Tsujino, Soichiro; Tomizaki, Takashi

    2016-01-01

    Increasing the data acquisition rate of X-ray diffraction images for macromolecular crystals at room temperature at synchrotrons has the potential to significantly accelerate both structural analysis of biomolecules and structure-based drug developments. Using lysozyme model crystals, we demonstrated the rapid acquisition of X-ray diffraction datasets by combining a high frame rate pixel array detector with ultrasonic acoustic levitation of protein crystals in liquid droplets. The rapid spinn...

  2. Large low-field magnetoresistance of Fe3O4 nanocrystal at room temperature

    International Nuclear Information System (INIS)

    Mi, Shu; Liu, Rui; Li, Yuanyuan; Xie, Yong; Chen, Ziyu

    2017-01-01

    Superparamagnetic magnetite (Fe 3 O 4 ) nanoparticles with an average size of 6.5 nm and good monodispersion were synthesized and investigated by X-ray diffraction, Raman spectrometer, transmission electron microscopy and vibrating sample magnetometer. Corresponding low-field magnetoresistance (LFMR) was tested by physical property measurement system. A quite high LFMR has been observed at room temperature. For examples, at a field of 3000 Oe, the LFMR is −3.5%, and when the field increases to 6000 Oe, the LFMR is up to −5.1%. The electron spin polarization was estimated at 25%. This result is superior to the previous reports showing the LFMR of no more than 2% at room temperature. The conduction mechanism is proposed to be the tunneling of conduction electrons between adjacent grains considering that the monodisperse nanocrystals may supply more grain boundaries increasing the tunneling probability, and consequently enhancing the overall magnetoresistance. - Highlights: • Superparamagnetic Fe3O4 nanoparticles with small size were synthesized. • A quite high LFMR has been observed at room temperature. • The more grain boundaries increase the tunneling probability and enlarge the MR. • The fast response of the sample increase the MR at a low field.

  3. 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.

  4. Magneto-transport properties of magnetic tunnelling transistors at low and room temperatures

    International Nuclear Information System (INIS)

    Quang, H D; Huu, C X; Oh, S K; Dang, V S; Sinh, N H; Yu, S C

    2006-01-01

    Si(100)/CoFe/AlO x /CoFe/FeMn/Cu/Ta magnetic tunnelling transistors (MTTs) with differing base thicknesses (W) were investigated. The magneto-transport properties of the MTTs were measured at 77 K and room temperature (RT). We obtained magneto-current ratios of 48.3% and 55.9% for emitter-base bias voltages of 1.45 and 2.0 V, respectively, at 77 K. The transfer ratios are 2.83 x 10 -5 and 1.52 x 10 -4 , respectively, corresponding to bias voltages of 1.45 and 2.0 V. Moreover, the highest tunnel magneto-resistance (TMR) ratios turned out to be 12% and 20% for a base thickness of 30 A at RT and 77 K, respectively. These properties raise not only some fundamental questions regarding the phenomenon of spin-independent tunnelling at low and room temperatures, but also show some promising aspect for magneto-electronic applications. In addition, we attempted to elucidate the reason behind the outstanding TMR effect at low and room temperatures. Finally, the origin of the decrease in the mean free path asymmetry (λ↑/λ↓) was clarified by using x-ray photoelectron spectroscopy profile analysis of the elements existing in the interface between Si and the CoFe base (Co, Fe, Al, Si, O)

  5. Ageing-assisted room temperature synthesis of La2Mo2O9 powders

    International Nuclear Information System (INIS)

    Li, Bao-rang; Tan, Hong; Zhang, De-long; Zhang, Nai-qiang

    2016-01-01

    Without any templates, hollow structured La 2 Mo 2 O 9 particles are successfully prepared at room temperature by an ageing-assisted salt solvent process. Powder X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy are used to investigate structure and morphologies of the obtained products. It is found that the ageing process has a significant influence on the particle morphology evolution when the mixed precursors are disposed at room temperature. With the ageing time changed from one week to 12 weeks, the particles morphologies evolve gradually from ellipsoid to sphere. The as-prepared hollow structured La 2 Mo 2 O 9 spheres have an average diameter of about 800 nm and shell thickness of about 100 nm. For elucidating the possible formation mechanism, the influences of the single salt on the particles morphologies evolution are also investigated. The final results indicate KCl is a key factor for formation of La 2 Mo 2 O 9 spheres and the formation of the hollow structure should have close relations with the surface tension in the ageing assisted process. - Highlights: • Ageing-assisted salt solvent process was designed to prepare La 2 Mo 2 O 9 . • Hollow structured La 2 Mo 2 O 9 micro-spheres are synthesized at room temperature for the first time. • The possible formation mechanism was discussed.

  6. Room Temperature Gas Sensing of Two-Dimensional Titanium Carbide (MXene).

    Science.gov (United States)

    Lee, Eunji; VahidMohammadi, Armin; Prorok, Barton C; Yoon, Young Soo; Beidaghi, Majid; Kim, Dong-Joo

    2017-10-25

    Wearable gas sensors have received lots of attention for diagnostic and monitoring applications, and two-dimensional (2D) materials can provide a promising platform for fabricating gas sensors that can operate at room temperature. In the present study, the room temperature gas-sensing performance of Ti 3 C 2 T x nanosheets was investigated. 2D Ti 3 C 2 T x (MXene) sheets were synthesized by removal of Al atoms from Ti 3 AlC 2 (MAX phases) and were integrated on flexible polyimide platforms with a simple solution casting method. The Ti 3 C 2 T x sensors successfully measured ethanol, methanol, acetone, and ammonia gas at room temperature and showed a p-type sensing behavior. The fabricated sensors showed their highest and lowest response toward ammonia and acetone gas, respectively. The limit of detection of acetone gas was theoretically calculated to be about 9.27 ppm, presenting better performance compared to other 2D material-based sensors. The sensing mechanism was proposed in terms of the interactions between the majority charge carriers of Ti 3 C 2 T x and gas species.

  7. Room Temperature Single Walled Carbon Nanotubes (SWCNT Chemiresistive Ammonia Gas Sensor

    Directory of Open Access Journals (Sweden)

    Bala Sekhar DASARI

    2015-07-01

    Full Text Available Single walled carbon nanotubes were functionalized with carboxyl (–COOH group using simple acid treatment process. Thin films of functionalized SWCNTs were fabricated using drop cast technique from the dispersion prepared in de-ionized water. These films were characterized using FE-SEM, FTIR, Raman spectroscopy techniques and current-voltage measurements were carried at room and elevated temperature. SWCNT chemiresistor gas sensor devices on silicon substrate were fabricated using conventional microfabrication technology with pristine and functionalized SWCNTs. Fabricated gas sensors were exposed to ammonia in an in-house developed gas sensor characterization system and response was measured at ammonia concentration up to 50 ppm at room temperature. Functionalized SWCNTs chemiresistor showed an impressive ammonia response of 20.2 % compared with 2.9 % of pristine counterpart. Response enhancement mechanisms are discussed in terms of defects and gas molecule adsorption on CNT surface. The achieved results are a step towards development of miniaturized, room temperature ammonia sensor for environment pollution monitoring and control.

  8. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Origin of Ferrimagnetism and Ferroelectricity in Room-Temperature Multiferroic ɛ -Fe2O3

    Science.gov (United States)

    Xu, K.; Feng, J. S.; Liu, Z. P.; Xiang, H. J.

    2018-04-01

    Exploring and identifying room-temperature multiferroics is critical for developing better nonvolatile random-access memory devices. Recently, ɛ -Fe2O3 was found to be a promising room-temperature multiferroic with a large polarization and magnetization. However, the origin of the multiferroicity in ɛ -Fe2O3 is still puzzling. In this work, we perform density-functional-theory calculations to reveal that the spin frustration between tetrahedral-site Fe3 + spins gives rise to the unexpected ferrimagnetism. For the ferroelectricity, we identify a low-energy polarization switching path with an energy barrier of 85 meV /f .u . by performing a stochastic surface walking simulation. The switching of the ferroelectric polarization is achieved by swapping the tetrahedral Fe ion with the octahedral Fe ion, different from the usual case (e.g., in BaTiO3 and BiFeO3 ) where the coordination number remains unchanged after the switching. Our results not only confirm that ɛ -Fe2O3 is a promising room-temperature multiferroic but also provide guiding principles to design high-performance multiferroics.

  10. Corrosion rate of copper in aqueous lithium bromide concentrated solutions at room temperature by immersion tests

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Portero, M.J.; Garcia-Anton, J.; Guinon-Segura, J.L.; Perez-Herranz, V. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)

    2004-07-01

    Concentrated solutions of lithium bromide (LiBr) are widely used in absorption refrigeration and heating systems. However, LiBr solutions can cause serious corrosion problems in structural materials (copper, steels, and other metals) in an absorption plant. The aim of the present work was the study of the corrosion rate of copper in 400 and 700 g/L (4.61 and 8.06 M) LiBr solutions pre-nitrogenous or pre-oxygenated at room temperature by immersion tests. The corroded copper concentration was determined with two techniques: weight-loss method and polarographic method. The corrosion curves of copper in LiBr solutions at room temperature as a function of the exposure time showed a similar tendency, and were fitted to a power function such as: C = kt{sup b}, where C was the corroded copper quantity per unit area (mg/cm{sup 2}), t was the exposure time (h), k was the corrosion coefficient, and b was the time exponent. From the corrosion coefficient values (k) it was deduced that the corrosion rate of copper in LiBr solutions at room temperature followed the order: 400 g/L (bubble of O{sub 2}) > 400 g/L (bubble of N{sub 2}) > 700 g/L (bubble of O{sub 2}) > 700 g/L (bubble of N{sub 2}). (authors)

  11. Contribution to the characterization of room temperature ionic liquids under ionizing irradiation

    International Nuclear Information System (INIS)

    Le Rouzo, G.; Lamouroux, Ch.; Moutiers, G.

    2010-01-01

    Room-Temperature Ionic Liquids are potentially interesting for nuclear fuel treatment. Within this framework, ionic liquids stability towards ionizing radiations (α, β or γ) is determining their potential application. The aim of this work is to assess a better understanding of ionic liquids behaviour under radiolysis. Ionic liquids chosen in these studies are constituted with BuMeIm + (or Bu 3 MeN + ) cation associated with various anions: Tf 2 N - , TfO - , PF 6 - and BF 4 - . Moreover, development of suitable chemical analysis tools crucial for characterization of these compounds has been realized. Ionic liquids stability has been mainly studied under γ irradiation, but also under electron beam or heavy particles irradiations. Ionic liquids degradation under radiolysis has been determined with two complementary approaches. The first one aims at understanding radio-induced degradation mechanisms with radical species analysis by Electron Paramagnetic Resonance spectroscopy (EPR). The second one aims at characterizing stable radiolysis products formed in liquid and gaseous phases. Studies were conducted with several analytical techniques: Electro Spray Ionisation Mass Spectrometry (ESI-MS), High Pressure Liquid Chromatography (HPLC, HPLC/UV-VIS, HPLC/ESI-MS), Gas Analysis Mass Spectrometry (Gas MS) and Gas Chromatography hyphenated with Mass Spectrometry (GC/MS). Firstly, the ionic liquid [Bu 3 MeIm][Tf 2 N] has been studied under γ irradiation. Radiolytic stability has been quantitatively assessed for high doses of radiations and a proposal of degradation scheme has been proposed on the basis of radio-induced radicals and radiolysis products analysis. Those data have been compared to those obtained for the γ radiolysis of the ionic liquid [Bu 3 MeN][Tf 2 N], enabling to assess cation influence on ionic liquids radiolysis. Secondly, degradation under γ irradiation of ionic liquids [BuMeIm][X] (X - Tf 2 N - , TfO - , PF 6 - , BF 4 - ) has been quantitatively

  12. Effect of calcination temperature on formaldehyde oxidation performance of Pt/TiO2 nanofiber composite at room temperature

    Science.gov (United States)

    Xu, Feiyan; Le, Yao; Cheng, Bei; Jiang, Chuanjia

    2017-12-01

    Catalytic oxidation at room temperature over well-designed catalysts is an environmentally friendly method for the abatement of indoor formaldehyde (HCHO) pollution. Herein, nanocomposites of platinum (Pt) and titanium dioxide (TiO2) nanofibers with various phase compositions were prepared by calcining the electrospun TiO2 precursors at different temperatures and subsequently depositing Pt nanoparticles (NPs) on the TiO2 through a NaBH4-reduction process. The phase compositions and structures of Pt/TiO2 can be easily controlled by varying the calcination temperature. The Pt/TiO2 nanocomposites showed a phase-dependent activity towards the catalytic HCHO oxidation. Pt/TiO2 containing pure rutile phase showed enhanced activity with a turnover frequency (TOF) of 16.6 min-1 (for a calcination temperature of 800 °C) as compared to those containing the anatase phase or mixed phases. Density functional theory calculation shows that TiO2 nanofibers with pure rutile phase have stronger adsorption ability to Pt atoms than anatase phase, which favors the reduction of Pt over rutile phase TiO2, leading to higher contents of metallic Pt in the nanocomposite. In addition, the Pt/TiO2 with rutile phase possesses more abundant oxygen vacancies, which is conducive to the activation of adsorbed oxygen. Consequently, the Pt/rutile-TiO2 nanocomposite exhibited better catalytic activity towards HCHO oxidation at room temperature.

  13. Effect of room temperature ionic liquid structure on the enzymatic acylation of flavonoids

    DEFF Research Database (Denmark)

    Lue, Bena-Marie; Guo, Zheng; Xu, Xuebing

    2010-01-01

    Enzymatic acylation reactions of flavonoids (rutin, esculin) with long chain fatty acids (palmitic, oleic acids) were carried out in 14 different ionic liquid media containing a range of cation and anion structures. Classification of RTILs according to flavonoid solubility (using COSMO...... must be struck that maximized flavonoid solubility with minimum negative impact on lipase activity. The process also benefitted from an increased reaction temperature which may have helped to reduced mass transfer limitations. Keywords: Room temperature ionic liquids (RTILs); Biosynthesis; Acylation......; Flavonoids; Lipase; Long chain fatty acids...

  14. Compositional invariance of magnetocaloric effect near room temperature in Ni-Mn-Sb-Al systems

    Science.gov (United States)

    Agarwal, Sandeep; Mukhopadhyay, P. K.

    2018-02-01

    A systematic study of structural transformation, magnetism and magnetic entropy change in the vicinity of structural and magnetic transformation has been performed in the Ni2Mn1.36Sb0.64 by substituting Sb with a large amount of Al. This substitution enhanced the transformation temperature close to room temperature and also made it less sensitive to the variation in composition. Alloys exhibited conventional and inverse magnetocaloric effects due to the Curie and magnetostructural transformation respectively. The inverse magnetocaloric effects were less compared to those reported in pure Sb system, but it showed a large value of conventional magnetocaloric effect with the added advantage of insensitivity to the compositional variation.

  15. Room temperature tensile ductility in polycrystalline B2 Ni-30Al-20Fe

    Science.gov (United States)

    Guha, Sumit; Munroe, Paul; Baker, Ian

    1989-01-01

    A room-temperature tensile elongation of about 2.5 percent, where the only slip vector observed was the 100, has been determined for a double-extruded B2 Ni-30Al-20Fe alloy consisting of recrystallized equiaxed grains about 25 microns in diameter; these results suggest that 100-slip does not preclude limited ductility in polycrystalline B2 alloys in tension at low temperatures. A suppression of ordering through resort to rapid solidification, in other words, is not necessary for ductility, since the cast and as-extruded alloy presently examined is ordered.

  16. Directionally Solidified NiAl-Based Alloys Studied for Improved Elevated-Temperature Strength and Room-Temperature Fracture Toughness

    Science.gov (United States)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2000-01-01

    Efforts are underway to replace superalloys used in the hot sections of gas turbine engines with materials possessing better mechanical and physical properties. Alloys based on the intermetallic NiAl have demonstrated potential; however, they generally suffer from low fracture resistance (toughness) at room temperature and from poor strength at elevated temperatures. Directional solidification of NiAl alloyed with both Cr and Mo has yielded materials with useful toughness and elevated-temperature strength values. The intermetallic alloy NiAl has been proposed as an advanced material to extend the maximum operational temperature of gas turbine engines by several hundred degrees centigrade. This intermetallic alloy displays a lower density (approximately 30-percent less) and a higher thermal conductivity (4 to 8 times greater) than conventional superalloys as well as good high-temperature oxidation resistance. Unfortunately, unalloyed NiAl has poor elevated temperature strength (approximately 50 MPa at 1027 C) and low room-temperature fracture toughness (about 5 MPa). Directionally solidified NiAl eutectic alloys are known to possess a combination of high elevated-temperature strength and good room-temperature fracture toughness. Research has demonstrated that a NiAl matrix containing a uniform distribution of very thin Cr plates alloyed with Mo possessed both increased fracture toughness and elevated-temperature creep strength. Although attractive properties were obtained, these alloys were formed at low growth rates (greater than 19 mm/hr), which are considered to be economically unviable. Hence, an investigation was warranted of the strength and toughness behavior of NiAl-(Cr,Mo) directionally solidified at faster growth rates. If the mechanical properties did not deteriorate with increased growth rates, directional solidification could offer an economical means to produce NiAl-based alloys commercially for gas turbine engines. An investigation at the NASA Glenn

  17. Thermophysical and spectroscopic studies of room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate in Tritons

    International Nuclear Information System (INIS)

    Chaudhary, Ganga Ram; Bansal, Shafila; Mehta, S.K.; Ahluwalia, A.S.

    2012-01-01

    Highlights: ► Thermophysical studies of new formulations of [BMIM][PF 6 ]+TX(45,100) have been made. ► Strong intermolecular interactions between [BMIM][PF 6 ] and TX (45, 100) is observed. ► Magnitude of interactions increases with the addition of oxyethylene groups in TX. ► With rise in temperature, intermolecular interactions increases. ► Spectroscopic studies show that interactions are via aromatic rings of RTIL and TX. - Abstract: The thermophysical properties viz. density ρ, speed of sound u, and specific conductivity κ of pure room temperature ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) and its binary formulations with Triton X-45 and Triton X-100 have been studied over the entire composition range at different temperatures (293.15 to 323.15) K. Excess molar volume V E , deviation in isentropic compressibility ΔK S , partial molar excess volume V i E , deviation in partial molar isentropic compressibility ΔK S,i , deviation in specific conductivity Δκ have also been estimated and analysed. Spectroscopic properties (IR, 1 H and 13 C NMR) of these mixtures have been investigated in order to understand the structural and interactional behaviour of formulations studied. The magnitude of interactions between the two components increases with addition of number of oxyethylene groups in Tritons and with rise in temperature. Spectroscopic measurements indicate that interactions are mainly taking place through the five member ring of room temperature ionic liquid and six member ring of Tritons.

  18. Effect of Temperature on the Aging rate of Li Ion Battery Operating above Room Temperature.

    Science.gov (United States)

    Leng, Feng; Tan, Cher Ming; Pecht, Michael

    2015-08-06

    Temperature is known to have a significant impact on the performance, safety, and cycle lifetime of lithium-ion batteries (LiB). However, the comprehensive effects of temperature on the cyclic aging rate of LiB have yet to be found. We use an electrochemistry-based model (ECBE) here to measure the effects on the aging behavior of cycled LiB operating within the temperature range of 25 °C to 55 °C. The increasing degradation rate of the maximum charge storage of LiB during cycling at elevated temperature is found to relate mainly to the degradations at the electrodes, and that the degradation of LCO cathode is larger than graphite anode at elevated temperature. In particular, the formation and modification of the surface films on the electrodes as well as structural/phase changes of the LCO electrode, as reported in the literatures, are found to be the main contributors to the increasing degradation rate of the maximum charge storage of LiB with temperature for the specific operating temperature range. Larger increases in the Warburg elements and cell impedance are also found with cycling at higher temperature, but they do not seriously affect the state of health (SoH) of LiB as shown in this work.

  19. Room temperature nanojoining of Cu-Ag core-shell nanoparticles and nanowires

    International Nuclear Information System (INIS)

    Wang, Jiaqi; Shin, Seungha

    2017-01-01

    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.

  20. Room temperature nanojoining of Cu-Ag core-shell nanoparticles and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiaqi; Shin, Seungha, E-mail: sshin@utk.edu [The University of Tennessee, Department of Mechanical, Aerospace and Biomedical Engineering (United States)

    2017-02-15

    Room temperature (T{sub 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{sub 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{sub 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.

  1. Effects of Nano-Aluminum Nitride on the Performance of an Ultrahigh-Temperature Inorganic Phosphate Adhesive Cured at Room Temperature

    Directory of Open Access Journals (Sweden)

    Chengkun Ma

    2017-11-01

    Full Text Available Based on the optimal proportion of resin and curing agent, an ultrahigh-temperature inorganic phosphate adhesive was prepared with aluminum dihydric phosphate, aluminium oxide ( α -Al2O3, etc. and cured at room temperature (RT. Then, nano-aluminum nitride (nano-AlN, nano-Cupric oxide (nano-CuO, and nano-titanium oxide (nano-TiO2 were added into the adhesive. Differential scanning calorimetry was conducted using the inorganic phosphate adhesive to analyze the phosphate reactions during heat treatment, and it was found that 15 wt % nano-AlN could clearly decrease the curing temperature. Scanning electron microscopy was used to observe the microphenomenon of the modified adhesive at ultrahigh-temperature. The differential thermal analysis of the inorganic phosphate adhesive showed that the weight loss was approximately 6.5 wt % when the mass ratio of resin to curing agent was 1:1.5. An X-ray diffraction analysis of the adhesive with 10% nano-AlN showed that the phase structure changed from AlPO4(11-0500 to the more stable AlPO4(10-0423 structure after heat treatment. The shear strength of the adhesive containing 10% nano-AlN reached 7.3 MPa at RT due to the addition of nano-AlN, which promoted the formation of phosphate and increased the Al3+.

  2. Effects of Nano-Aluminum Nitride on the Performance of an Ultrahigh-Temperature Inorganic Phosphate Adhesive Cured at Room Temperature.

    Science.gov (United States)

    Ma, Chengkun; Chen, Hailong; Wang, Chao; Zhang, Jifeng; Qi, Hui; Zhou, Limin

    2017-11-03

    Based on the optimal proportion of resin and curing agent, an ultrahigh-temperature inorganic phosphate adhesive was prepared with aluminum dihydric phosphate, aluminium oxide ( α -Al₂O₃), etc. and cured at room temperature (RT). Then, nano-aluminum nitride (nano-AlN), nano-Cupric oxide (nano-CuO), and nano-titanium oxide (nano-TiO₂) were added into the adhesive. Differential scanning calorimetry was conducted using the inorganic phosphate adhesive to analyze the phosphate reactions during heat treatment, and it was found that 15 wt % nano-AlN could clearly decrease the curing temperature. Scanning electron microscopy was used to observe the microphenomenon of the modified adhesive at ultrahigh-temperature. The differential thermal analysis of the inorganic phosphate adhesive showed that the weight loss was approximately 6.5 wt % when the mass ratio of resin to curing agent was 1:1.5. An X-ray diffraction analysis of the adhesive with 10% nano-AlN showed that the phase structure changed from AlPO₄(11-0500) to the more stable AlPO₄(10-0423) structure after heat treatment. The shear strength of the adhesive containing 10% nano-AlN reached 7.3 MPa at RT due to the addition of nano-AlN, which promoted the formation of phosphate and increased the Al 3+ .

  3. Precipitation and temperature effects on stable fly (diptera: muscidae) population dynamics

    Science.gov (United States)

    The dynamics of stable fly, Stomoxys calcitrans (L.), populations relative to temperature and precipitation were evaluated in a 13 y study in eastern Nebraska. During the course of the study, over 1.7 million stable flies were collected on an array of 25 sticky traps. A log-normal model using degree...

  4. A temperature-stable cryo-system for high-temperature superconducting MR in-vivo imaging.

    Directory of Open Access Journals (Sweden)

    In-Tsang Lin

    Full Text Available To perform a rat experiment using a high-temperature superconducting (HTS surface resonator, a cryostat is essential to maintain the rat's temperature. In this work, a compact temperature-stable HTS cryo-system, keeping animal rectal temperature at 37.4°C for more than 3 hours, was successfully developed. With this HTS cryo-system, a 40-mm-diameter Bi2Sr2Ca2Cu3Ox (Bi-2223 surface resonator at 77 K was demonstrated in a 3-Tesla MRI system. The proton resonant frequency (PRF method was employed to monitor the rat's temperature. Moreover, the capacity of MR thermometry in the HTS experiments was evaluated by correlating with data from independent fiber-optic sensor temperature measurements. The PRF thermal coefficient was derived as 0.03 rad/°C and the temperature-monitoring architecture can be implemented to upgrade the quality and safety in HTS experiments. The signal-to-noise ratio (SNR of the HTS surface resonator at 77 K was higher than that of a professionally made copper surface resonator at 300 K, which has the same geometry, by a 3.79-fold SNR gain. Furthermore, the temperature-stable HTS cryo-system we developed can obtain stable SNR gain in every scan. A temperature-stable HTS cryo-system with an external air-blowing circulation system is demonstrated.

  5. Application of Eh-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media

    International Nuclear Information System (INIS)

    Al-Hinai, Ashraf T.; Al-Hinai, Muna H.; Dutta, Joydeep

    2014-01-01

    Graphical abstract: - Highlights: • One pot aqueous synthesis of zinc stannate (ZnSnO 3 ) particles at low temperature. • Synthesis designed with the assistance of potential-pH diagram. • ZnSnO 3 estimated to be stable between pH 8 and 12 was used for synthesis of the particles. • ZnSnO 3 ·3H 2 O were formed during the precipitation of zinc stannate. - Abstract: Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO 3 ) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn 2+ and Sn 4+ was controlled for the precipitation in a one pot synthesis step at room temperature (25 °C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn 2+ + Sn 4+ ) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization of nano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO 3 ·3H 2 O form

  6. Impact of Prolonged Blood Incubation and Extended Serum Storage at Room Temperature on the Human Serum Metabolome

    Directory of Open Access Journals (Sweden)

    Beate Kamlage

    2018-01-01

    Full Text Available Metabolomics is a powerful technology with broad applications in life science that, like other -omics approaches, requires high-quality samples to achieve reliable results and ensure reproducibility. Therefore, along with quality assurance, methods to assess sample quality regarding pre-analytical confounders are urgently needed. In this study, we analyzed the response of the human serum metabolome to pre-analytical variations comprising prolonged blood incubation and extended serum storage at room temperature by using gas chromatography-mass spectrometry (GC-MS and liquid chromatography-tandem mass spectrometry (LC-MS/MS -based metabolomics. We found that the prolonged incubation of blood results in a statistically significant 20% increase and 4% decrease of 225 tested serum metabolites. Extended serum storage affected 21% of the analyzed metabolites (14% increased, 7% decreased. Amino acids and nucleobases showed the highest percentage of changed metabolites in both confounding conditions, whereas lipids were remarkably stable. Interestingly, the amounts of taurine and O-phosphoethanolamine, which have both been discussed as biomarkers for various diseases, were 1.8- and 2.9-fold increased after 6 h of blood incubation. Since we found that both are more stable in ethylenediaminetetraacetic acid (EDTA blood, EDTA plasma should be the preferred metabolomics matrix.

  7. Low-magnetic field, room-temperature colossal magnetoresistance in manganite thin films

    Science.gov (United States)

    Robson, Marcia Christine

    The manganese (Mn) based perovskite oxide materials (manganites), of the chemical form T1--xDxMnO3, display a large magnetic field induced decrease in their resistivity, termed colossal magnetoresistance. Typically, colossal magnetoresistance in the manganite samples is observed at low temperatures and high magnetic fields (>1 Tesla). However, an enhanced magnetoresistance at low magnetic fields and room temperature in these manganite samples would be technologically useful. In an effort to characterize this low magnetic field, room temperature magnetoresistance, the role of several different physical parameters has been explored in this thesis. These physical parameters include lattice mismatch strain, which originates from the epitaxial growth of single layer manganite thin films, the application of different radiation probes, such as microwave radiation, and the introduction of artificial grain boundaries in the form of interfaces in manganite multilayers. Lattice mismatch strain originates from the difference in the lattice constants of the manganite thin film and the crystalline substrate. The nature of the effect of the lattice mismatch strain on these transport properties for La0.7Ba0.3MnO3 thin films has been studied by varying the degree of lattice mismatch strain in the thin film. Variation of the lattice mismatch strain was achieved by varying the thickness of the manganite thin films, by annealing the manganite thin films in oxygen, and by buffering the manganite films with a lattice matched buffer layer. Each of these approaches relaxed the lattice mismatch strain, resulting in an increase of the low magnetic field, room temperature magnetoresistance. Microwave radiation probes determine the magnetic homogeneity of the manganite thin films and the effect of this magnetic homogeneity on the low magnetic field, room temperature magnetoresistance. La0.7Ba 0.3MnO3 thin films showed no gross magnetic homogeneitiese. The magnetic homogeneity increased in the

  8. 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. Copyright © 2015. Published by Elsevier B.V.

  9. La0.7Sr0.3MnO3 Thin Films for Magnetic and Temperature Sensors at Room Temperature

    Directory of Open Access Journals (Sweden)

    Sheng Wu

    2012-03-01

    Full Text Available In this paper, the potentialities of the manganese oxide La0.7Sr0.3MnO3 (LSMO for the realization of sensitive room temperature thermometers and magnetic sensors are discussed. LSMO exhibits both a large change of the resistance versus temperature at its metal-to-insulator transition (about 330 K and low field magnetoresistive effects at room temperature. The sensor performances are described in terms of signal-to-noise ratio in the 1 Hz - 100 kHz frequency range. It is shown that due to the very low 1/f noise level, LSMO based sensors can exhibit competitive performances at room temperature.

  10. One-Dimensional Vanadium Dioxide Nanostructures for Room Temperature Hydrogen Sensors

    Directory of Open Access Journals (Sweden)

    Aline Simo

    2015-06-01

    Full Text Available In relation to hydrogen (H2 economy in general and gas sensing in particular, an extensive set of one dimensional (1-D nano-scaled oxide materials are being investigated as ideal candidates for potential gas sensing applications. This is correlated to their set of singular surface characteristics, shape anisotropy and readiness for integrated devices. Nanostructures of well- established gas sensing materials such as Tin Oxide (SnO2, Zinc Oxide (ZnO, Indium (III Oxide (In2O3, and Tungsten Trioxide (WO3 have shown higher sensitivity and gas selectivity, quicker response, faster time recovery, as well as an enhanced capability to detect gases at low concentrations. While the overall sensing characteristics of these so called 1-D nanomaterials are superior, they are efficient at high temperature; generally above 200 0C. This operational impediment results in device complexities in integration that limit their technological applications, specifically in their miniaturized arrangements. Unfortunately, for room temperature applications, there is a necessity to dope the above mentioned nano-scaled oxides with noble metals such as Platinum (Pt, Palladium (Pd, Gold (Au, Ruthenium (Ru. This comes at a cost. This communication reports, for the first time, on the room temperature enhanced H2 sensing properties of a specific phase of pure Vanadium Dioxide (VO2 phase A in their nanobelt form. The relatively observed large H2 room temperature sensing in this Mott type specific oxide seems to reach values as low as 14 ppm H2 which makes it an ideal gas sensing in H2 fuelled systems.

  11. Temperature, hospital admissions and emergency room visits in Lhasa, Tibet: a time-series analysis.

    Science.gov (United States)

    Bai, Li; Cirendunzhu; Woodward, Alistair; Dawa; Zhaxisangmu; Chen, Bin; Liu, Qiyong

    2014-08-15

    Tibet of China, with an average altitude of over 4000 m, has experienced noticeable changes in its climate over the last 50 years. The association between temperature and morbidity (most commonly represented by hospital admissions) has been documented mainly in developed countries. Little is known about patterns in China; nor have the health effects of temperature variations been closely studied in highland areas, worldwide. We investigated the temperature-morbidity association in Lhasa, the capital city of Tibet, using sex- and age-specific hospitalizations, excluding those due to external causes. A distributed lag non-linear model (DLNM) was applied to assess the nonlinear and delayed effects of temperature on morbidity (including total emergency room visits, total and cause-specific hospital admissions, sex- and age-specific non-external admissions). High temperatures are associated with increases in morbidity, to a greater extent than low temperatures. Lag effects of high and low temperatures were cause-specific. The relative risks (RR) of high temperature for total emergency room visits and non-external hospitalizations were 1.162 (95% CI: 1.002-1.349) and 1.161 (95% CI: 1.007-1.339) respectively, for lag 0-14 days. The strongest cumulative effect of heat for lag 0-27 days was on admissions for infectious diseases (RR: 2.067, 95% CI: 1.026-4.027). Acute heat effects at lag 0 were related with increases of renal (RR: 1.478, 95% CI: 1.005-2.174) and respiratory diseases (RR: 1.119, 95% CI: 1.010-1.240), whereas immediate cold effects increased admission for digestive diseases (RR: 1.132, 95% CI: 1.002-1.282). Those ≥65 years of age and males were more vulnerable to high temperatures. We provide a first look at the temperature-morbidity relationship in Tibet. Exposure to both hot and cold temperatures resulted in increased admissions to hospital, but the immediate causes varied. We suggest that initiatives should be taken to reduce the adverse effects of

  12. Determination of hydrogen diffusivity and permeability in W near room temperature applying a tritium tracer technique

    International Nuclear Information System (INIS)

    Ikeda, T.; Otsuka, T.; Tanabe, T.

    2011-01-01

    Tungsten is a primary candidate of plasma facing material in ITER and beyond, owing to its good thermal property and low erosion. But hydrogen solubility and diffusivity near ITER operation temperatures (below 500 K) have scarcely studied. Mainly because its low hydrogen solubility and diffusivity at lower temperatures make the detection of hydrogen quite difficult. We have tried to observe hydrogen plasma driven permeation (PDP) through nickel and tungsten near room temperatures applying a tritium tracer technique, which is extremely sensible to detect tritium diluted in hydrogen. The apparent diffusion coefficients for PDP were determined by permeation lag times at first time, and those for nickel and tungsten were similar or a few times larger than those for gas driven permeation (GDP). The permeation rates for PDP in nickel and tungsten were larger than those for GDP normalized to the same gas pressure about 20 and 5 times larger, respectively.

  13. Two-dimensional mathematical model of a reciprocating room-temperature Active Magnetic Regenerator

    DEFF Research Database (Denmark)

    Petersen, Thomas Frank; Pryds, Nini; Smith, Anders

    2008-01-01

    and water as the heat transfer fluid. The results show that the AMR is able to obtain a no-load temperature span of 10.9 K in a 1 T magnetic field with a corresponding work input of 93.0 kJ m−3 of gadolinium per cycle. The model shows significant temperature differences between the regenerator and the heat......A time-dependent, two-dimensional mathematical model of a reciprocating Active Magnetic Regenerator (AMR) operating at room-temperature has been developed. The model geometry comprises a regenerator made of parallel plates separated by channels of a heat transfer fluid and a hot as well as a cold...

  14. Annealing of neutron damage in graphite irradiated and stored at room temperature

    International Nuclear Information System (INIS)

    Gray, W.J.; Thrower, P.A.

    1979-01-01

    Annealing of neutron radiation damage in graphite at the same temperature at which it was irradiated is reported. Highly oriented pyrolytic graphite samples were irradiated to fluences in the range 0.44 to 153 x 10 15 /cm 2 at room temperature using three different neutron sources with average energies of 1.5, 5.5, and 15 MeV, respectively. Following these irradiations, the C 44 elastic constants of the samples were measured several times over periods up to two years during which time sample temperatures never exceeded 30 0 C. The C 44 constants were observed to slowly decrease toward their unirradiated values with up to 40% of the irradiation-induced changes eventually annealing out

  15. Dual origin of room temperature sub-terahertz photoresponse in graphene field effect transistors

    Science.gov (United States)

    Bandurin, D. A.; Gayduchenko, I.; Cao, Y.; Moskotin, M.; Principi, A.; Grigorieva, I. V.; Goltsman, G.; Fedorov, G.; Svintsov, D.

    2018-04-01

    Graphene is considered as a promising platform for detectors of high-frequency radiation up to the terahertz (THz) range due to its superior electron mobility. Previously, it has been shown that graphene field effect transistors (FETs) exhibit room temperature broadband photoresponse to incoming THz radiation, thanks to the thermoelectric and/or plasma wave rectification. Both effects exhibit similar functional dependences on the gate voltage, and therefore, it was difficult to disentangle these contributions in previous studies. In this letter, we report on combined experimental and theoretical studies of sub-THz response in graphene field-effect transistors analyzed at different temperatures. This temperature-dependent study allowed us to reveal the role of the photo-thermoelectric effect, p-n junction rectification, and plasmonic rectification in the sub-THz photoresponse of graphene FETs.

  16. Investigations of Heat Transfer in Vacuum between Room Temperature and 80 K

    Science.gov (United States)

    Hooks, J.; Demko, J. A.; E Fesmire, J.; Matsumoto, T.

    2017-12-01

    The heat transfer between room temperature and 80 K is controlled using various insulating material combinations. The modes of heat transfer are well established to be conduction and thermal radiation when in a vacuum. Multi-Layer Insulation (MLI) in a vacuum has long been the best approach. Typically this layered system is applied to the cold surface. This paper investigates the application of MLI to both the cold and warm surface to see whether there is a significant difference. In addition if MLI is on the warm surface, the cold side of the MLI may be below the critical temperature of some high temperature superconducting (HTS) materials. It has been proposed that HTS materials can serve to block thermal radiation. An experiment is conducted to measure this effect. Boil-off calorimetry is the method of measuring the heat transfer.

  17. Formation of nanocrystalline barium titanate in benzyl alcohol at room temperature.

    Science.gov (United States)

    Veldhuis, Sjoerd A; Vijselaar, Wouter J C; Stawski, Tomasz M; ten Elshof, Johan E

    2014-12-15

    Nanocrystalline barium titanate (8-10 nm crystallite size) was prepared at temperatures of 23-78 °C through reaction of a modified titanium alkoxide precursor in benzyl alcohol with barium hydroxide octahydrate. The room temperature formation of a perovskite phase from solution is associated with the use of benzyl alcohol as solvent medium. The formation mechanism was elucidated by studying the stability and interaction of each precursor with the solvent and with each other using various experimental characterization techniques. Density functional theory (DFT) computational models which agreed well with our experimental data could explain the formation of the solid phase. The stability of the Ti precursor was enhanced by steric hindrance exerted by phenylmethoxy ligands that originated from the benzyl alcohol solvent. Electron microscopy and X-ray diffraction indicated that the crystallite sizes were independent of the reaction temperature. Crystal growth was inhibited by the stabilizing phenylmethoxy groups present on the surface of the crystallites.

  18. 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.

  19. Mechanistic insights into the room temperature transitions of polytetrafluoroethylene during electron-beam irradiation

    Science.gov (United States)

    Fu, Congli; Yu, Xianwei; Zhao, Xiaofeng; Wang, Xiuli; Gu, Aiqun; Xie, Meiju; Chen, Chen; Yu, Zili

    2017-11-01

    In order to recognize the characteristic thermal transitions of polytetrafluoroethylene (PTFE) occurring at 19 °C and 30 °C, PTFE is irradiated on electron beam accelerator at room temperature and analyzed by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results suggest that the two transition temperatures decrease considerably with increasing irradiation doses. Based on the results of structural analysis, the decrease of the two transition temperatures is supposed to be highly relevant to the structural changes. In particular, the content and structure of the side groups generated in PTFE are responsible for the variations of the two thermal transitions after irradiation, offering fundamental insights into the reaction mechanisms of PTFE during irradiation.

  20. Cubic MnSb: Epitaxial growth of a predicted room temperature half-metal

    Science.gov (United States)

    Aldous, James D.; Burrows, Christopher W.; Sánchez, Ana M.; Beanland, Richard; Maskery, Ian; Bradley, Matthew K.; Dos Santos Dias, Manuel; Staunton, Julie B.; Bell, Gavin R.

    2012-02-01

    Epitaxial films including bulklike cubic and wurtzite polymorphs of MnSb have been grown by molecular beam epitaxy on GaAs via careful control of the Sb4/Mn flux ratio. Nonzero-temperature density functional theory was used to predict ab initio the half-metallicity of the cubic polymorph and compare its spin polarization as a function of reduced magnetization with that of the well known half-metal NiMnSb. In both cases, half-metallicity is lost at a threshold magnetization reduction, corresponding to a temperature T*350 K, making epitaxial cubic MnSb a promising candidate for efficient room temperature spin injection into semiconductors.

  1. 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.

  2. Controllable deposition of regular lead iodide nanoplatelets and their photoluminescence at room temperature

    Science.gov (United States)

    Kong, Weimin; Li, Guohui; Liang, Qiangbing; Ji, Xingqi; Li, Gang; Ji, Ting; Che, Tao; Hao, Yuying; Cui, Yanxia

    2018-03-01

    In this work, the synthesis of regular single crystalline lead iodide nanoplatelets are carried out based on the physical vapor phase deposition method. Different lead iodide nanoplatelets are obtained by tuning the location of the mica substrate along with the temperature of the tube furnace. The rules of size, thickness, density of the lead iodide nanoplatelets at varied deposition conditions are analyzed according to the crystal growth principles. It was claimed in literature that the photoluminescence of lead iodide could be obtained only at a low temperature (lower than 200 K). Here, at room temperature, we successfully obtained the photoluminescence spectra of the prepared lead iodide nanoplatelets, which possess two apparent peaks due to the biexcitons and the inelastic scattering of excitons, respectively. Our present study contributes to the development of nanoscaled high performance optoelectronic devices.

  3. Modeling of the transient behavior of heat pipes with room-temperature working fluids

    Science.gov (United States)

    Brocheny, Pascal O.

    2006-07-01

    The heat pipe is a capillary-driven and two-phase flow device, capable of transporting and converting large amounts of energy with minimal losses. As a means of thermal management, uses of heat pipe technology not only include thermal control of satellites and spacecrafts in aerospace applications, but also the cooling of electronic components for ground applications. Recently, there has been a flourishing interest in exploring the use of heat pipe technology in the automotive field. However, in many thermal control applications, heat pipes using room-temperature working fluids, such as water or ammonia, with operating temperatures between 200 K (-73ºC) and 550 K (277ºC), can hardly operate at steady state conditions. The study of transient heat pipe phenomena becomes a significant area of research interests including not only startup and shutdown phases, but also heat redistribution, changes of thermal loading and heat removal. The transient performance is affected by thermal capacity and conductance of the heat pipe, capillary pumping forces, heating and cooling conditions. In the present study, the transient operations of different conventional room-temperature heat pipes were investigated analytically, including the capillary dryout and rewetting behaviors occurring at the evaporator section during startups. The physical model is based on the displacement of a leading-edge front of a thin liquid layer flowing on finite groove uniformly heated with a constant heat flux. A one-dimensional transient heat conduction model along the evaporator wall is coupled with the movement of the fluid layer during startup. Numerical solutions were obtained by a fully implicit Finite Difference Method, accounting for the movement of the liquid and a known time-variable temperature boundary condition at the liquid front. The velocity and position of the liquid front were found to vary with the applied heat flux, the initial conditions, and the thermophysical properties of the

  4. Room-Temperature Quantum Coherence and Rabi Oscillations in Vanadyl Phthalocyanine: Toward Multifunctional Molecular Spin Qubits.

    Science.gov (United States)

    Atzori, Matteo; Tesi, Lorenzo; Morra, Elena; Chiesa, Mario; Sorace, Lorenzo; Sessoli, Roberta

    2016-02-24

    Here we report the investigation of the magnetic relaxation and the quantum coherence of vanadyl phthalocyanine, VOPc, a multifunctional and easy-processable potential molecular spin qubit. VOPc in its pure form (1) and its crystalline dispersions in the isostructural diamagnetic host TiOPc in different stoichiometric ratios, namely VOPc:TiOPc 1:10 (2) and 1:1000 (3), were investigated via a multitechnique approach based on the combination of alternate current (AC) susceptometry, continuous wave, and pulsed electron paramagnetic resonance (EPR) spectroscopy. AC susceptibility measurements revealed a linear increase of the relaxation rate with temperature up to 20 K, as expected for a direct mechanism, but τ remains slow over a very wide range of applied static field values (up to ∼5 T). Pulsed EPR spectroscopy experiments on 3 revealed quantum coherence up to room temperature with T(m) ∼1 μs at 300 K, representing the highest value obtained to date for molecular electronic spin qubits. Rabi oscillations are observed in this nuclear spin-active environment ((1)H and (14)N nuclei) at room temperature also for 2, indicating an outstanding robustness of the quantum coherence in this molecular semiconductor exploitable in spintronic devices.

  5. Room-temperature spin-orbit torque in NiMnSb

    Science.gov (United States)

    Ciccarelli, C.; Anderson, L.; Tshitoyan, V.; Ferguson, A. J.; Gerhard, F.; Gould, C.; Molenkamp, L. W.; Gayles, J.; Železný, J.; Šmejkal, L.; Yuan, Z.; Sinova, J.; Freimuth, F.; Jungwirth, T.

    2016-09-01

    Materials that crystallize in diamond-related lattices, with Si and GaAs as their prime examples, are at the foundation of modern electronics. Simultaneously, inversion asymmetries in their crystal structure and relativistic spin-orbit coupling led to discoveries of non-equilibrium spin-polarization phenomena that are now extensively explored as an electrical means for manipulating magnetic moments in a variety of spintronic structures. Current research of these relativistic spin-orbit torques focuses primarily on magnetic transition-metal multilayers. The low-temperature diluted magnetic semiconductor (Ga, Mn)As, in which spin-orbit torques were initially discovered, has so far remained the only example showing the phenomenon among bulk non-centrosymmetric ferromagnets. Here we present a general framework, based on the complete set of crystallographic point groups, for identifying the potential presence and symmetry of spin-orbit torques in non-centrosymmetric crystals. Among the candidate room-temperature ferromagnets we chose to use NiMnSb, which is a member of the broad family of magnetic Heusler compounds. By performing all-electrical ferromagnetic resonance measurements in single-crystal epilayers of NiMnSb we detect room-temperature spin-orbit torques generated by effective fields of the expected symmetry and of a magnitude consistent with our ab initio calculations.

  6. Room temperature creep-fatigue response of selected copper alloys for high heat flux applications

    International Nuclear Information System (INIS)

    Li Meimei; Singh, B.N.; Stubbins, J.F.

    2004-01-01

    Two copper alloys, dispersion-strengthened CuAl25 and precipitation-hardened CuCrZr, were examined under fatigue and fatigue with hold time loading conditions. Tests were carried out at room temperature and hold times were imposed at maximum tensile and maximum compressive strains. It was found that hold times could be damaging even at room temperature, well below temperatures typically associated with creep. Hold times resulted in shorter fatigue lives in the high cycle fatigue, long life regime (i.e., at low strain amplitudes) than those of materials tested under the same conditions without hold times. The influence of hold times on fatigue life in the low cycle fatigue, short life regime (i.e., at high strain amplitudes) was minimal. When hold time effects were observed, fatigue lives were reduced with hold times as short as two seconds. Appreciable stress relaxation was observed during the hold period at all applied strain levels in both tension and compression. In all cases, stresses relaxed quickly within the first few seconds of the hold period and much more gradually thereafter. The CuAl25 alloy showed a larger effect of hold time on reduction of high cycle fatigue life than did the CuCrZr alloy

  7. Sweetness concentration-response behavior of rebiana at room and refrigerator temperatures.

    Science.gov (United States)

    Fry, John C; Yurttas, Nese; Biermann, Kari L

    2011-01-01

    Rebiana is a zero-calorie, natural, high-potency sweetener derived from Stevia rebaudiana Bertoni and comprising almost pure rebaudioside A. Reliable information on its sweetness concentration-response (C-R) behavior is fundamental to rebiana's use as an ingredient. The response curve of rebiana in room-temperature (21 °C) and refrigerated (5 °C) water was determined using 2-alternative forced choice discrimination tests with a minimum of 70 tasters. From a series of panels the proportion of tasters finding different sucrose concentrations sweeter than a fixed concentration of rebiana was plotted against sucrose concentration. The resultant sigmoid curves were linearized by transforming the ordinate axis to a probability scale. This aided experimental design and determination of isosweet concentrations. The latter were deemed to be the sucrose concentration at which 50% of tasters found it to be the sweeter of the pair. Isosweet concentrations of sucrose for seven rebiana concentrations up to 600 mg/L were used to construct a C-R curve for each temperature. Equations were derived for the resultant hyperbolic curves. Rebiana is significantly more potent in cold water. Rebiana is a new, zero-calorie, natural, high-potency sweetener derived from the Stevia plant. We have measured the sweetness of rebiana over a range of concentrations at room and refrigerator temperatures. This information will help developers of low-calorie products get the right sweetness level when replacing sugar with rebiana. © 2011 Institute of Food Technologists®

  8. OMNY PIN—A versatile sample holder for tomographic measurements at room and cryogenic temperatures

    Science.gov (United States)

    Holler, M.; Raabe, J.; Wepf, R.; Shahmoradian, S. H.; Diaz, A.; Sarafimov, B.; Lachat, T.; Walther, H.; Vitins, M.

    2017-11-01

    Nowadays ptychographic tomography in the hard x-ray regime, i.e., at energies above about 2 keV, is a well-established measurement technique. At the Paul Scherrer Institut, currently two instruments are available: one is measuring at room temperature and atmospheric pressure, and the other, the so-called OMNY (tOMography Nano crYo) instrument, is operating at ultra-high vacuum and offering cryogenic sample temperatures down to 10 K. In this manuscript, we present the sample mounts that were developed for these instruments. Aside from excellent mechanical stability and thermal conductivity, they also offer highly reproducible mounting. Various types were developed for different kinds of samples and are presented in detail, including examples of how specimens can be mounted on these holders. We also show the first hard x-ray ptychographic tomography measurements of high-pressure frozen biological samples, in the present case Chlamydomonas cells, the related sample pins and preparation steps. For completeness, we present accessories such as transportation containers for both room temperature and cryogenic samples and a gripper mechanism for automatic sample changing. The sample mounts are not limited to x-ray tomography or hard x-ray energies, and we believe that they can be very useful for other instrumentation projects.

  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. Fabry-Pérot Oscillation and Room Temperature Lasing in Perovskite Cube-Corner Pyramid Cavities

    KAUST Repository

    Mi, Yang

    2018-01-10

    Recently, organometal halide perovskite-based optoelectronics, particularly lasers, have attracted intensive attentions because of its outstanding spectral coherence, low threshold, and wideband tunability. In this work, high-quality CH3 NH3 PbBr3 single crystals with a unique shape of cube-corner pyramids are synthesized on mica substrates using chemical vapor deposition method. These micropyramids naturally form cube-corner cavities, which are eminent candidates for small-sized resonators and retroreflectors. The as-grown perovskites show strong emission ≈530 nm in the vertical direction at room temperature. A special Fabry-Pérot (F-P) mode is employed to interpret the light confinement in the cavity. Lasing from the perovskite pyramids is observed from 80 to 200 K, with threshold ranging from ≈92 µJ cm-2 to 2.2 mJ cm-2 , yielding a characteristic temperature of T0 = 35 K. By coating a thin layer of Ag film, the threshold is reduced from ≈92 to 26 µJ cm-2 , which is accompanied by room temperature lasing with a threshold of ≈75 µJ cm-2 . This work advocates the prospect of shape-engineered perovskite crystals toward developing micro-sized optoelectronic devices and potentially investigating light-matter coupling in quantum optics.

  11. 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.

  12. 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)

  13. 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)

  14. Integrated Interface Strategy toward Room Temperature Solid-State Lithium Batteries.

    Science.gov (United States)

    Ju, Jiangwei; Wang, Yantao; Chen, Bingbing; Ma, Jun; Dong, Shanmu; Chai, Jingchao; Qu, Hongtao; Cui, Longfei; Wu, Xiuxiu; Cui, Guanglei

    2018-04-25

    Solid-state lithium batteries have drawn wide attention to address the safety issues of power batteries. However, the development of solid-state lithium batteries is substantially limited by the poor electrochemical performances originating from the rigid interface between solid electrodes and solid-state electrolytes. In this work, a composite of poly(vinyl carbonate) and Li 10 SnP 2 S 12 solid-state electrolyte is fabricated successfully via in situ polymerization to improve the rigid interface issues. The composite electrolyte presents a considerable room temperature conductivity of 0.2 mS cm -1 , an electrochemical window exceeding 4.5 V, and a Li + transport number of 0.6. It is demonstrated that solid-state lithium metal battery of LiFe 0.2 Mn 0.8 PO 4 (LFMP)/composite electrolyte/Li can deliver a high capacity of 130 mA h g -1 with considerable capacity retention of 88% and Coulombic efficiency of exceeding 99% after 140 cycles at the rate of 0.5 C at room temperature. The superior electrochemical performance can be ascribed to the good compatibility of the composite electrolyte with Li metal and the integrated compatible interface between solid electrodes and the composite electrolyte engineered by in situ polymerization, which leads to a significant interfacial impedance decrease from 1292 to 213 Ω cm 2 in solid-state Li-Li symmetrical cells. This work provides vital reference for improving the interface compatibility for room temperature solid-state lithium batteries.

  15. Synthesis, characterization and performance of zinc ferrite nanorods for room temperature sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Archana; Singh, Ajendra [Macromolecular Research Laboratory, Department of Physics, University of Lucknow, Lucknow 226007, U.P. (India); Singh, Satyendra, E-mail: satyendra_nano84@rediffmail.com [Department of Physics, University of Allahabad, Allahabad 211002, U.P. (India); Tandon, Poonam [Macromolecular Research Laboratory, Department of Physics, University of Lucknow, Lucknow 226007, U.P. (India); Yadav, B.C. [Department of Applied Physics, School for Physical Sciences, Babasaheb Bhimrao Ambedkar University, Lucknow 226025, U.P. (India); Yadav, R.R. [Department of Physics, University of Allahabad, Allahabad 211002, U.P. (India)

    2015-01-05

    Highlights: • Fabrication of zinc ferrite thin film LPG and CO{sub 2} gas sensors. • Morphological growth of nanorods. • Significant advancement towards the fabrication of a reliable LPG sensor. • A new pathway to produce nanorods as sensorial material. - Abstract: In the present communication, nanorods of zinc ferrite was synthesized and fabricated by employing sol–gel spin coating process. The synthesized material was characterized using X-ray diffraction, scanning electron microscopy, acoustic particle sizer, atomic force microscopy, UV–visible absorption and infrared spectroscopic techniques. Thermal properties were investigated using differential scanning calorimetry. The XRD reveals cubic spinel structure with minimum crystallite size 10 nm. SEM image of the film shows porous surface morphology with uniform distribution of nanorods. The band gap of the zinc ferrite nanorods was found 3.80 eV using the Tauc plot. ZnFe{sub 2}O{sub 4} shows weak super paramagnetic behavior at room temperature investigated using the vibrating sample magnetometer. Further, the liquefied petroleum gas (LPG) and carbon dioxide gas (CO{sub 2}) sensing properties of the fabricated film were investigated at room temperature (25 °C). More variations in electrical resistance were observed for LPG in comparison to CO{sub 2} gas. The parameters such as lattice constant, X-ray density, porosity and specific surface area were also calculated for the better understanding of the observed gas sensing properties. High sensitivity and percentage sensor response, small response and recovery times, good reproducibility and stability characterized the fabricated sensor for the detection of LPG at room temperature.

  16. Structural characterization of sputtered indium oxide films deposited at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hotovy, I., E-mail: ivan.hotovy@stuba.s [Department of Microelectronics, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Pezoldt, J. [FG Nanotechnologie, Institut fuer Mikro- und Nanoelektronik, TU Ilmenau, Postfach 100565, 98684 Ilmenau (Germany); Kadlecikova, M. [Department of Microelectronics, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Kups, T.; Spiess, L. [FG Werkstoffe der Elektrotechnik, Institut fuer Werkstofftechnik, TU Ilmeau, Postfach 100565, 98684 Ilmenau (Germany); Breza, J. [Department of Microelectronics, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Sakalauskas, E.; Goldhahn, R. [FG Exprimentalphysik I, Institut fuer Physik, TU Ilmenau, Postfach 100565, 98684 Ilmenau (Germany); Rehacek, V. [Department of Microelectronics, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia)

    2010-06-01

    Structural evolution of indium oxide thin films deposited at room temperature by reactive magnetron sputtering and annealing in a reducing atmosphere were investigated. The as deposited indium oxide (In{sub 2}O{sub 3}) films showed a dominating randomly oriented nanocrystalline structure of cubic In{sub 2}O{sub 3}. The grain size decreased with increasing oxygen concentration in the plasma. Annealing in reducing atmospheres (vacuum, nitrogen and argon), besides improving the crystallinity, led to a partial cubic to rhombohedral phase transition in the indium oxide films. Annealing improved the optical properties of the indium oxide film and shifted the absorption edge to higher energies.

  17. ScBO/sub 3/: Cr-A room temperature near-infrared tunable laser

    International Nuclear Information System (INIS)

    Lai, S.T.; Chai, B.H.T.; Long, M.; Morris, R.C.

    1986-01-01

    The authors report the first room temperature tunable laser in a borate single crystal. A tuning range of 787-892 nm has been demonstrated in a ScBO/sub 3/:Cr laser. The laser loss is estimated to be 1.3 percent/cm from our preliminary laser results. Spectroscopic measurements indicate that the material is clear of absorption loss in the lasing spectral region, and the relative fluorescence efficiency for the entire Cr absorption band in the visible region is nearly unit. ScBO/sub 3/:Cr holds promise as a high efficiency near-infrared tunable laser

  18. Crystal grain growth during room temperature high pressure Martensitic alpha to omega transformation in zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Velisavljevic, Nenad [Los Alamos National Laboratory; Chesnut, Gary N [Los Alamos National Laboratory; Stevens, Lewis L [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory

    2008-01-01

    Systematic increase in transition pressure with increase in interstitial impurities is observed for the martensitic {alpha} {yields} {omega} structural phase transition in Zr. Significant room temperature crystal grain growth is also observed for the two highest purity samples at this transition, while in the case of the lowest purity sample interstitial impurities obstruct grain growth even as the sample is heated to 1279 K. Our results show the importance of impurities in controlling structural phase stability and other mechanical properties associated with the {alpha} {yields} {omega} structural phase transition.

  19. Etching characteristics of a CR-39 track detector at room temperature in different etching solutions

    International Nuclear Information System (INIS)

    Dajko, G.

    1991-01-01

    Investigations were carried out to discover how the etching characteristics of CR-39 detectors change with varying conditions of the etching process. Measurements were made at room temperature in pure NaOH and KOH solutions; in different alcoholic KOH solutions (PEW solution, i.e. potassium hydroxide, ethyl alcohol, water); and in NaOH and KOH solutions containing different additives. The bulk etching rate of the detector (V B ) and the V (= V T /V B ) function, i.e. track to bulk etch rates ratio, for 6.1 MeV α-particles, were measured systematically. (author)

  20. 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......We report on a novel optical near-field technique to measure the local polarizability of a topographically flat sample with a spatial resolution better than 100 nm. Using an uncoated fiber probe, we implement a cross-polarization detection of the optical signal at the fiber dither frequency...

  1. Room-temperature synthesis and photoluminescence of hexagonal CePO4 nanorods

    Science.gov (United States)

    Zhu, J.; Zhang, K.; Zhao, H. Y.

    2018-01-01

    Hexagonal CePO4 nanorods were synthesized via a simple chemical precipitation route at room-temperature without the presence of surfactants and then characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectrometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV–vis) absorption and photoluminescence (PL) spectroscopy. Hexagonal CePO4 nanorods exhibit strong ultraviolet absorption and ultraviolet luminescence, which correspond to the electronic transitions between 4f and 5d state of Ce3+ ions.

  2. Converse magnetoelectric experiments on a room-temperature spirally ordered hexaferrite

    Science.gov (United States)

    Ebnabbasi, Khabat; Vittoria, Carmine; Widom, Allan

    2012-07-01

    Magnetoelectric properties of room-temperature spirally ordered Sr3Co2Fe24O41 hexaferrite slabs have been measured. A physical model in this paper referred to as the “slinky helix” model is presented to explain the experimental data. The measured properties include the magnetic permeability and the strain, all as a function of the electric field E. Upon application of an electric field to slabs of Sr Z-type hexaferrite, it exhibits broken symmetries for time reversal and parity. This is the central feature of these magnetoelectric materials.

  3. 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.

  4. Evolution of Texture and Mechanical Properties of Pure Mg Processed by ECAP at Room Temperature

    Science.gov (United States)

    Lei, Weiwei; Liang, Wei; Wang, Hongxia; Guo, Hongwei

    2017-11-01

    Equal channel angular pressing (ECAP) was performed on extruded pure Mg, which was clad with a drilled pure Fe coat through an ECAP die to produce a pure Mg sample without obvious cracks at room temperature. After one-pass ECAP, the grain size decreased because of basal slip activation during the dynamic plastic deformation but the microstructure became inhomogeneous. The deformed texture was less scattered and inclined by 20° from the normal direction toward the extruded direction, and low angle boundaries increased continuously. The mechanical properties decreased slightly as a result of the combined effect from a more refined microstructure and a weaker texture.

  5. Room Temperature Ionic Liquids as Green Solvent Alternatives in the Metathesis of Oleochemical Feedstocks

    Directory of Open Access Journals (Sweden)

    Priya A. Thomas

    2016-02-01

    Full Text Available One of the most important areas of green chemistry is the application of environmentally friendly solvents in catalysis and synthesis. Conventional organic solvents pose a threat to the environment due to the volatility, highly flammability, toxicity and carcinogenic properties they exhibit. The recently emerged room temperature ionic liquids (RTILs are promising green solvent alternatives to the volatile organic solvents due to their ease of reuse, non-volatility, thermal stability and ability to dissolve a variety of organic and organometallic compounds. This review explores the use of RTILs as green solvent media in olefin metathesis for applications in the oleochemical industry.

  6. Tensile properties of unirradiated PCA from room temperature to 7000C

    International Nuclear Information System (INIS)

    Braski, D.N.; Maziasz, P.J.

    1983-01-01

    The tensile properties of Prime Candidate Alloy (PCA) austenitic stainless steel after three different thermomechanical treatments were determined from room temperature to 700 0 C. The solution-annealed PCA had the lowest strength and highest ductility, while the reverse was true for the 25%-cold-worked material. The PCA containing titanium-rich MC particles fell between the other two heats. The cold-worked PCA had nearly the same tensile properties as cold-worked type 316 stainless steel. Both alloys showed ductility minima at 300 0 C

  7. Room temperature synthesis of wurtzite phase nanostructured ZnS and accompanied enhancement in dielectric constant

    Science.gov (United States)

    Virpal, Kumar, J.; Singh, G.; Singh, M.; Sharma, S.; Singh, R. C.

    2017-04-01

    We report the room temperature synthesis of ZnS in the wurtzite phase by using ethylenediamine, which acts as a template as well as a capping agent. With the addition of ethylenediamine, structural transformation in ZnS from cubic to wurtzite phase is observed. This is accompanied by an increase in the real permittivity by an order of 2, and reduction in dielectric loss by a factor of 6 as compared to a sample without ethylenediamine. Thus, suggesting that ethylenediamine capped wurtzite ZnS is more suitable for miniaturied capactive devices.

  8. Room-Temperature Voltage Tunable Phonon Thermal Conductivity via Reconfigurable Interfaces in Ferroelectric Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Ihlefeld, Jon F. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Foley, Brian M. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Mechanical and Aerospace Engineering; Scrymgeour, David A. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Michael, Joseph R. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); McKenzie, Bonnie B. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Medlin, Douglas L. [Sandia National Laboratories, Livermore, CA; Wallace, Margeaux [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering; Trolier-McKinstry, Susan [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering; Hopkins, Patrick E. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Mechanical and Aerospace Engineering

    2015-02-19

    Dynamic control of thermal transport in solid-state systems is a transformative capability with the promise to propel technologies including phononic logic, thermal management, and energy harvesting. A solid-state solution to rapidly manipulate phonons has escaped the scientific community. Here, we demonstrate active and reversible tuning of thermal conductivity by manipulating the nanoscale ferroelastic domain structure of a Pb(Zr0.3Ti0.7)O3 film with applied electric fields. With subsecond response times, the room-temperature thermal conductivity was modulated by 11%.

  9. Study of dielectric liquids at room temperature for high energy x ray Tomography

    International Nuclear Information System (INIS)

    Lepert, S.

    1989-09-01

    The detection of X rays by means of a dielectric liquid detector system, at room temperature, is discussed. The physico-chemical properties of a dielectric liquid, the construction of a cleaning device and of two electrode configurations, and the utilization of different amplifier models are studied. The results allowed the analysis and characterization of the behavior of the dielectric liquid under X ray irradiation. Data obtained is confirmed by computerized simulation. The choice of Tetramethyl-germanium for the X ray tomography, applied in nondestructive analysis, is explained. The investigation of the system parameters allowed the setting of the basis of a prototype project for a multi-detector [fr

  10. Discussion of superconducting and room-temperature high-intensity ion linacs

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1996-01-01

    The point of view taken in this discussion is that the basic technology base exists in all essential respects for both superconducting or room-temperature rf linac accelerators and associated power and control systems, and thus a project can make a choice between these technologies on overall system considerations. These include performance, cost, availability, flexibility, and upgradability. Large high-intensity neutron source proposals involving light-ion rf linacs in three categories are reviewed in this context. The categories arc cw linacs to high (∼1 GeV) and low (∼40 MeV) output energy, and pulsed linacs to energy ∼1 GeV

  11. Relationship between room temperature phosphorescence and deuteration position in a purely aromatic compound

    Science.gov (United States)

    Hirata, S.; Totani, K.; Watanabe, T.; Kaji, H.; Vacha, M.

    2014-01-01

    The development of organometallic and purely organic compounds showing room temperature phosphorescence (RTP) has several promising applications. We report a relationship between the phosphorescence characteristics and deuteration position in a purely organic aromatic compound. Hydrogen-deuterium exchange at the carbons where the lowest unoccupied molecular orbital is located is the most effective method to enhance the RTP lifetime and quantum yield. The increase in RTP lifetime comes from a decrease in the Franck-Condon factor while the enhancement of RTP yield is caused by an increase in intersystem crossing from the lowest singlet excited state to the lowest triplet excited state.

  12. Gas Transport Properties of PEBAX®/Room Temperature Ionic Liquid Gel Membranes

    Czech Academy of Sciences Publication Activity Database

    Bernardo, P.; Jansen, J. C.; Bazzarelli, F.; Tasselli, F.; Fuoco, A.; Friess, K.; Izák, Pavel; Jarmarová, Veronika; Kačírková, Marie; Clarizia, G.

    2012-01-01

    Roč. 97, SI (2012), s. 73-82 ISSN 1383-5866. [Conference on Ionic Liquids in Separation and Purification Technology (ILSEPT) /1./. Sitges, 04.09.2011-07.09.2011] R&D Projects: GA ČR GAP106/10/1194 Grant - others:RFCS(XE) RFCR-CT-2010-00009 Institutional support: RVO:67985858 Keywords : room temperature ionic liquid * ionic liquid * polymer gel Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.894, year: 2012

  13. Room Temperature Ferromagnetic, Anisotropic, Germanium Rich FeGe(001) Alloys

    OpenAIRE

    Lungu, George A.; Apostol, Nicoleta G.; Stoflea, Laura E.; Costescu, Ruxandra M.; Popescu, Dana G.; Teodorescu, Cristian M.

    2013-01-01

    Ferromagnetic Fe x Ge1?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 ...

  14. Room temperature microwave-assisted recording on 500-Gbpsi-class perpendicular medium

    Science.gov (United States)

    Nozaki, Y.; Ishida, N.; Soeno, Y.; Sekiguchi, K.

    2012-10-01

    Microwave-assisted recording on a 500-Gbpsi-class perpendicular medium was experimentally demonstrated at room temperature. Magnetization reversal under a radio-frequency magnetic field was measured by an electrically shorted coplanar waveguide, which enabled us to evaluate the change in the medium's ferromagnetic resonance spectrum. A frequency-dependent reduction in the switching field was clearly observed in response to a microwave impulse 50 ns in duration. A significant reduction of up to 30% in the coercive field was achieved by applying a microwave impulse with an amplitude of 25 dBm and a frequency of 15 GHz.

  15. Room temperature wafer direct bonding of smooth Si surfaces recovered by Ne beam surface treatments

    Science.gov (United States)

    Kurashima, Yuichi; Maeda, Atsuhiko; Takagi, Hideki

    2013-06-01

    We examined the applicability of a Ne fast atom beam (FAB) to surface activated bonding of Si wafers at room temperature. With etching depth more than 1.5 nm, the bonding strength comparable to Si bulk strength was attained. Moreover, we found the improvement of the bonding strength by surface smoothing effect of the Ne FAB. Silicon surface roughness decreased from 0.40 to 0.17 nm rms by applying a Ne FAB of 30 nm etching depth. The bonding strength between surfaces recovered by Ne FAB surface smoothing was largely improved and finally became equivalent to Si bulk strength.

  16. Magnetocardiography and magnetoencephalography measurements at room temperature using tunnel magneto-resistance sensors

    Science.gov (United States)

    Fujiwara, Kosuke; Oogane, Mikihiko; Kanno, Akitake; Imada, Masahiro; Jono, Junichi; Terauchi, Takashi; Okuno, Tetsuo; Aritomi, Yuuji; Morikawa, Masahiro; Tsuchida, Masaaki; Nakasato, Nobukazu; Ando, Yasuo

    2018-02-01

    Magnetocardiography (MCG) and magnetoencephalography (MEG) signals were detected at room temperature using tunnel magneto-resistance (TMR) sensors. TMR sensors developed with low-noise amplifier circuits detected the MCG R wave without averaging, and the QRS complex was clearly observed with averaging at a high signal-to-noise ratio. Spatial mapping of the MCG was also achieved. Averaging of MEG signals triggered by electroencephalography (EEG) clearly observed the phase inversion of the alpha rhythm with a correlation coefficient as high as 0.7 between EEG and MEG.

  17. Room Temperature Detection of Benzene Vapours by Tin Oxide Nano Clusters

    Directory of Open Access Journals (Sweden)

    J. N. PANCHAL

    2015-07-01

    Full Text Available Thin films of tin oxide with nano clusters were deposited using Chemical Vapour Transport technique. The annealed films were used as sensor to detect benzene vapours at room temperature. The response was studied for the concentration range 300-1000 ppm. A comparative study of the response of the nano clustered films to benzene vapours in this range with the response of thin films of Indium tin oxide and tin oxide deposited by the physical vapour deposition method was taken up.

  18. 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.

  19. 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.

  20. 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......)-phenylenevinylene (OPV3) derivatives, in which the central benzene ring is coupled to either para- or meta-positions. Using the break-junction technique, we find that the conductance for a single meta-OPV3 molecule wired between gold electrodes is one order of magnitude smaller than that of a para-OPV3 molecule...

  1. Machining and Phase Transformation Response of Room-Temperature Austenitic NiTi Shape Memory Alloy

    Science.gov (United States)

    Kaynak, Yusuf

    2014-09-01

    This experimental work reports the results of a study addressing tool wear, surface topography, and x-ray diffraction analysis for the finish cutting process of room-temperature austenitic NiTi alloy. Turning operation of NiTi alloy was conducted under dry, minimum quantity lubrication (MQL) and cryogenic cooling conditions at various cutting speeds. Findings revealed that cryogenic machining substantially reduced tool wear and improved surface topography and quality of the finished parts in comparison with the other two approaches. Phase transformation on the surface of work material was not observed after dry and MQL machining, but B19' martensite phase was found on the surface of cryogenically machined samples.

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

    DEFF Research Database (Denmark)

    Shen, Heng

    Abstract In this thesis, different experiments on spin squeezing and entanglement involving room temperature ensembles of Cesium atoms are described. The key method is the off-resonant Faraday interaction of spin-polarized atomic ensemble with a light field. And the key component is the micro......-fabricated vapor cell coupled into an optical cavity. Quantum backaction evading measurement of one quadrature of collective spin components by stroboscopically modulating the intensity of probe beam at twice Larmor frequency is used to generate the spin-squeezed state. A projection noise limited optical...... of spin states surpasses a classical benchmark, demonstrating the true quantum teleportation....

  3. Room temperature fatigue behavior of OFHC copper and CuAl25 specimens of two sizes

    DEFF Research Database (Denmark)

    Singhal, A.; Stubbins, J.F.; Singh, B.N.

    1994-01-01

    requiring an understanding of their fatigue behavior.This paper describes the room temperature fatigue behavior of unirradiated OFHC (oxygen-free high-conductivity) copper and CuAl25 (copper strengthened with a 0.25% atom fraction dispersion of alumina). The response of two fatigue specimen sizes to strain......Copper and its alloys are appealing for application in fusion reactor systems for high heat flux components where high thermal conductivities are critical, for instance, in divertor components. The thermal and mechanical loading of such components will be, at least in part, cyclic in nature, thus...

  4. Room temperature creep-fatigue response of selected copper alloys for high heat flux applications

    DEFF Research Database (Denmark)

    Li, M.; Singh, B.N.; Stubbins, J.F.

    2004-01-01

    Two copper alloys, dispersion-strengthened CuAl25 and precipitation-hardened CuCrZr, were examined under fatigue and fatigue with hold time loading conditions. Tests were carried out at room temperature and hold times were imposed at maximum tensile and maximum compressive strains. It was found...... the hold period at all applied strain levels in both tension and compression. In all cases, stresses relaxed quickly within the first few seconds of the hold period and much more gradually thereafter. The CuAl25 alloy showed a larger effect of hold time on reduction of high cycle fatigue life than did...... the CuCrZr alloy....

  5. Scaling of dynamical decoupling for a single electron spin in nanodiamonds at room temperature

    International Nuclear Information System (INIS)

    Liu, Dong-Qi; Liu, Gang-Qin; Chang, Yan-Chun; Pan, Xin-Yu

    2014-01-01

    Overcoming the spin qubit decoherence is a challenge for quantum science and technology. We investigate the decoherence process in nanodiamonds by Carr–Purcell–Meiboom–Gill (CPMG) technique at room temperature. We find that the coherence time T 2 scales as n γ . The elongation effect of coherence time can be represented by a constant power of the number of pulses n. Considering the filter function of CPMG decoupling sequence as a δ function, the spectrum density of noise has been reconstructed directly from the coherence time measurements and a Lorentzian noise power spectrum model agrees well with the experiment. These results are helpful for the application of nanodiamonds to nanoscale magnetic imaging

  6. An acoustic on-chip goniometer for room temperature macromolecular crystallography.

    Science.gov (United States)

    Burton, C G; Axford, D; Edwards, A M J; Gildea, R J; Morris, R H; Newton, M I; Orville, A M; Prince, M; Topham, P D; Docker, P T

    2017-12-05

    This paper describes the design, development and successful use of an on-chip goniometer for room-temperature macromolecular crystallography via acoustically induced rotations. We present for the first time a low cost, rate-tunable, acoustic actuator for gradual in-fluid sample reorientation about varying axes and its utilisation for protein structure determination on a synchrotron beamline. The device enables the efficient collection of diffraction data via a rotation method from a sample within a surface confined droplet. This method facilitates efficient macromolecular structural data acquisition in fluid environments for dynamical studies.

  7. The Genome-Wide DNA Methylation Profile of Peripheral Blood Is Not Systematically Changed by Short-Time Storage at Room Temperature

    Directory of Open Access Journals (Sweden)

    Nicklas Heine Staunstrup

    2017-12-01

    Full Text Available Background: Epigenetic epidemiology has proven an important research discipline in the delineation of diseases of complex etiology. The approach, in such studies, is often to use bio-banked clinical material, however, many such samples were collected for purposes other than epigenetic studies and, thus, potentially not processed and stored appropriately. The Danish National Birth Cohort (DNBC includes more than 100,000 peripheral and umbilical cord blood samples shipped from maternity wards by ordinary mail in EDTA tubes. While this and other similar cohorts hold great promises for DNA methylation studies the potential systematic changes prompted by storage at ambient temperatures have never been assessed on a genome-wide level. Methods and Results: In this study, matched EDTA whole blood samples were stored up to three days at room temperature prior to DNA extraction and methylated DNA immunoprecipitation coupled with deep sequencing (MeDIP-seq. We established that the quality of the MeDIP-seq libraries was high and comparable across samples; and that the methylation profiles did not change systematically during the short-time storage at room temperature. Conclusion: The global DNA methylation profile is stable in whole blood samples stored for up to three days at room temperature in EDTA tubes making genome-wide methylation studies on such material feasible.

  8. Room-temperature semiconductor detectors for in vivo monitoring of internal contamination.

    Science.gov (United States)

    Genicot, J L

    1997-01-01

    In vivo monitoring of low-energy X-ray and gamma-ray emitters has always been a difficult task, primarily because of lack of accuracy and the high detection limits of classical techniques. Various types of PIN diodes (diodes with a large intrinsic zone) were tested in the Radiation Protection Department of the Studie Centrum voor Kernenergie, Centre d'étude de l'Energie Nucléaire (Mol, Belgium) in the measurement of radioactive body burden by direct methods. Current research is oriented toward the use of room-temperature diodes for the detection of low-energy photons escaping the body. In this paper, a new counting technique that involves a portable jacket containing the diodes is described. The system uses silicon diodes and is used out of shielding room in order to be near the contamination. With this method rapid analysis and long counting times are possible, stress is reduced, and medical treatment can be optimized. CdZnTe detectors were also evaluated for this measurement technique but this type of detector is better adapted for counting inside a shielding room. The improvement of the accuracy of the measurement, taking into account the effect of the ribs, is described here, as well the associated electronics necessary for this type of counting. Images Figure 1. PMID:9467055

  9. 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.

  10. Monotonic and Fatigue Behavior of 2-D Woven Ceramic Matrix Composite at Room and Elevated Temperatures (Blackglas/Nextel 312)

    National Research Council Canada - National Science Library

    Al-Hussein, Musa

    1998-01-01

    This study investigated the monotonic tension and compression and the tension-tension and tension-compression fatigue loading of Blackglas/Nextel 312 woven CMC at room temperature and at 760 degrees centigrade...

  11. Use of Single-Tow Ceramic Matrix Minicomposites to Determine Fundamental Room and Elevated Temperature Properties

    Science.gov (United States)

    Almansour, Amjad S.

    The room and high temperature mechanical properties of continuous ceramic fiber reinforced matrix composites makes them attractive for implementation in aerospace and nuclear applications. However, the effect of fiber content has not been addressed in previous work. Therefore, single tow composites with fiber content ranging from 3 to 47 % was studied. Single fiber tow minicomposite is the basic architectural feature of woven and laminate ceramic matrix composites (CMCs). An in depth understanding of the initiation and evolution of damage in various ceramic fiber reinforced minicomposites with different fiber volume fractions and interphases was investigated employing several non-destructive evaluation techniques. A new technique is used to determine matrix crack content based on a damage parameter derived from speed of sound measurements which is compared with the established method using cumulative energy of Acoustic Emission (AE) events. Also, a modified theoretical model was implemented to obtain matrix stress at the onset of matrix cracking. Room temperature tensile, high temperature creep rupture and high temperature oxidation degradation loading conditions were all considered and composites' constituents were characterized. Moreover, fibers/matrix load sharing was modeled in creep and fiber volume fraction effect on load transfer was investigated using derived theoretical models. Fibers and matrix creep parameters, load transfer model results and numerical model methodology were used to construct minicomposites' creep strain model to predict creep damage of the different fiber type and content minicomposites. Furthermore, different fiber volume fractions ceramic matrix minicomposites' electrical resistivity temperature dependence isn't well understood. Therefore, the influence of fiber content, heat treatment cycles and creep on electrical resistivity measurements of SiC/SiC minicomposites were also studied here. Next, minicomposites' testing and

  12. Air temperature determination inside residual heat removal pump room of Angra-1 nuclear power plant after a design basic accident

    International Nuclear Information System (INIS)

    Siniscalchi, Marcio Rezende

    2005-01-01

    This work develops heat transfer theoretical models for determination of air temperature inside the Residual Heat Removal Pump Room of Angra 1 Nuclear Power Plant after a Design Basis Accident without forced ventilation. Two models had been developed. The differential equations are solved by analytical methods. A software in FORTRAN language are developed for simulations of temperature inside rooms for different geometries and materials. (author)

  13. Performance of room temperature mercuric iodide (HgI2) detectors in the ultra low energy x-ray region

    International Nuclear Information System (INIS)

    Dabrowski, A.J.; Iwanczyk, J.S.; Barton, J.B.; Huth, G.C.; Whited, R.; Ortale, C.; Economou, T.E.; Turkevich, A.L.

    1980-01-01

    Performance of room temperature mercuric iodide x-ray spectrometers has been recently improved through new fabrication techniques and further development of low noise associated electronic systems. This progress has extended the range of measurements to the ultra low energy x-ray region at room temperature. This paper reports the study of the effect of contact material on the performance of HgI 2 detectors in the low energy x-ray region

  14. Photonic Crystal Architecture for Room-Temperature Equilibrium Bose-Einstein Condensation of Exciton Polaritons

    Directory of Open Access Journals (Sweden)

    Jian-Hua Jiang

    2014-08-01

    Full Text Available We describe photonic crystal microcavities with very strong light-matter interaction to realize room-temperature, equilibrium, exciton-polariton Bose-Einstein condensation (BEC. This goal is achieved through a careful balance between strong light trapping in a photonic band gap (PBG and large exciton density enabled by a multiple quantum-well (QW structure with a moderate dielectric constant. This approach enables the formation of a long-lived, dense 10-μm-1-cm- scale cloud of exciton polaritons with vacuum Rabi splitting that is roughly 7% of the bare exciton-recombination energy. We introduce a woodpile photonic crystal made of Cd_{0.6}  Mg_{0.4}Te with a 3D PBG of 9.2% (gap-to-central-frequency ratio that strongly focuses a planar guided optical field on CdTe QWs in the cavity. For 3-nm QWs with 5-nm barrier width, the exciton-photon coupling can be as large as ℏΩ=55  meV (i.e., a vacuum Rabi splitting of 2ℏΩ=110  meV. The exciton-recombination energy of 1.65 eV corresponds to an optical wavelength of 750 nm. For N=106 QWs embedded in the cavity, the collective exciton-photon coupling per QW (ℏΩ/sqrt[N]=5.4  meV is much larger than the state-of-the-art value of 3.3 meV, for the CdTe Fabry-Pérot microcavity. The maximum BEC temperature is limited by the depth of the dispersion minimum for the lower polariton branch, over which the polariton has a small effective mass of approximately 10^{−5}m_{0}, where m_{0} is the electron mass in vacuum. By detuning the bare exciton-recombination energy above the planar guided optical mode, a larger dispersion depth is achieved, enabling room-temperature BEC. The BEC transition temperature ranges as high as 500 K when the polariton density per QW is increased to (11a_{B}^{−2}, where a_{B}≃3.5  nm is the exciton Bohr radius and the exciton-cavity detuning is increased to 30 meV. A high-quality PBG can suppress exciton radiative decay and enhance the polariton

  15. Observation of room temperature saturated ferroelectric polarization in Dy substituted BiFeO3 ceramics

    KAUST Repository

    Zhang, Shuxia

    2012-04-06

    High quality Bi1− x Dy x FeO3 (0 ≤ x ≤ 0.15) ceramics have been fabricated by sintering Dy-doped BiFeO3 (BFO) precursor powders at a low temperature of 780 °C. The magnetic properties of BFO were improved by the introduction of Dy on the Bi-site. More importantly, well saturated ferroelectric hysteresis loops and polarization switching currents have been observed at room temperature. A large remnant polarization (2P r) value of 62 μC/cm2 is achieved, which is the highest value reported so far for rare-earth-doped BFO ceramics. Moreover, mechanisms for improved multiferroic properties depending on chemical doping-caused structure evolutions have also been discussed.

  16. 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...

  17. Unusual Room Temperature Ferromagnetism in Bulk Sintered GaP Doped with Copper

    Energy Technology Data Exchange (ETDEWEB)

    Owens, F. J.; Gupta, A.; Rao, K. V.; Iqbal, Z.; Osorio Guillen, J. M.; Ahuja, R.; Guo, J.-H.

    2007-06-01

    Robust room temperature ferromagnetism is obtained in single phase Gallium Phosphide doped with Cu{sup 2+} prepared by simple solid state reaction route. The saturation magnetization at 300 K is 1.5 times 10{sup -2} emu/g and the coercivity was found to be 125 Oe. A strong ferromagnetic resonance signal confirms the long range magnetic order which persists to temperatures as high as 739 K. X-ray absorption spectroscopy (XAS) indicate that Cu is in a +2 state. Ab initio calculations also show that the ferromagnetic ordering is energetically favorable in Cu doped GaP. When the spin-orbit coupling is included we get an enhanced total magnetic moment of 0.31 muB with a local moment on Cu 0.082 and on P 0.204 mu{sub B}. per atom.

  18. Extraction of plutonium from lean residues by room temperature fluoride volatility

    International Nuclear Information System (INIS)

    Campbell, G.M.; Foropoulos, J.; Kennedy, R.C.; Dye, B.A.; Behrens, R.G.

    1989-01-01

    The use of dioxygen difluoride (FOOF) and KrF 2 for the recovery of Pu from lean residues by conversion to gaseous PuF 6 is being investigated. The greater stability of PuF 6 at room temperature allows much more extensive removal of Pu from contaminated wastes, when compared to the high temperature fluoride volatility process. The process also requires fewer additive chemicals than aqueous processes, thus minimizing the amount of material that must be disposed of as radioactive waste. The transportability of gaseous PuF 6 allows much of the process to be automated, reducing operator exposure to radiation. Removal of PuF 6 decomposition product is easily facilitated by the use of these fluorinating agents. 9 refs., 8 figs

  19. Solution-Mediated Annealing of Polymer Optical Fiber Bragg Gratings at Room Temperature

    DEFF Research Database (Denmark)

    Fasano, Andrea; Woyessa, Getinet; Janting, Jakob

    2017-01-01

    In this letter, we investigate the response of poly(methylmethacrylate) (PMMA) microstructured polymer optical fiber Bragg gratings (POFBGs) after immersion inmethanol/water solutions at room temperature. As the glass transition temperature of solution-equilibrated PMMA differs from the one...... of solvent-free PMMA, different concentrations of methanol and water lead to various degrees of frozen-in stress relaxation in the fiber. After solvent evaporation, we observe a permanent blue-shift in the grating resonance wavelength. The main contribution in the resonance wavelength shift arises from...... a permanent change in the size of the fiber. The results are compared with conventional annealing. The proposed methodology is cost-effective as it does not require a climate chamber. Furthermore, it enables an easy-to-control tuning of the resonance wavelength of POFBGs....

  20. Electrical detection of single magnetic skyrmions in metallic multilayers at room temperature

    Science.gov (United States)

    Maccariello, Davide; Legrand, William; Reyren, Nicolas; Garcia, Karin; Bouzehouane, Karim; Collin, Sophie; Cros, Vincent; Fert, Albert

    2018-01-01

    Magnetic skyrmions are topologically protected whirling spin textures that can be stabilized in magnetic materials by an asymmetric exchange interaction between neighbouring spins that imposes a fixed chirality. Their small size, together with the robustness against external perturbations, make magnetic skyrmions potential storage bits in a novel generation of memory and logic devices. To this aim, their contribution to the electrical transport properties of a device must be characterized—however, the existing demonstrations are limited to low temperatures and mainly in magnetic materials with a B20 crystal structure. Here we combine concomitant magnetic force microscopy and Hall resistivity measurements to demonstrate the electrical detection of sub-100 nm skyrmions in a multilayered thin film at room temperature. Furthermore, we detect and analyse the Hall signal of a single skyrmion, which indicates that it arises from the anomalous Hall effect with a negligible contribution from the topological Hall effect.

  1. Nanostructured Ferrite Based Electronic Nose Sensitive to Ammonia at Room Temperature

    Directory of Open Access Journals (Sweden)

    U. B. GAWAS

    2011-11-01

    Full Text Available Manganese and Nickel doped Zinc Ferrite powder (Mn0.3Ni0.3Zn0.4Fe2O4 was synthesized by autocatalytic thermal decomposition technique. The average crystallite size in the material powder was found to be of 10 – 13 nm. Characterization techniques such as X-Ray diffraction studies, Transmission electron microscopy, Infra-Red spectroscopy, etc, were employed to study the average particle size, phase and composition of the ferrite. Thick films of Mn0.3Ni0.3Zn0.4Fe2O4 were prepared by screen printing technique. These films were observed to be sensitive to 10 ppm NH3 at room temperature. The effects of surface microstructure, operating temperature, gas concentrations, etc., on the gas response, selectivity, response and recovery times of the sensor in the presence of NH3 and other gases were studied and discussed.

  2. Rapid room temperature solubilization and depolymerization of polymeric lignin at high loadings

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jian; Dutta, Tanmoy; Parthasarathi, Ramakrishnan; Kim, Kwang Ho; Tolic, Nikola; Chu, Rosalie K.; Isern, Nancy G.; Cort, John R.; Simmons, Blake A.; Singh, Seema

    2016-01-01

    The relatively poor solubility of lignin in most pretreatment solvents remains one of the biggest challegnes in lignin valorization to improve overall biorefinery economics. In this work, rapid room temperature solubilization of lignin at high solid loadings (>30 wt%) can be easily achieved in a single step using ethylene glycol (EG). The solubilized lignin can be rapidly and quantitively recovered with the addtion of ethanol. The computational and nuclear magnetic resonance (NMR) spectroscopic studies confirm that strong hydrogen bond interactions between EG and the free hydroxyl groups present in lignin contribute to the lignin dissolution. In addition, hydrogen peroxide mediated depolymerization of dissolved lignin at low temperature (80 oC) was tested and the effect of EG molecules on depolymerization of ligin was also theoritically studied. The findings of this work provide mechanistic insights of hydrogen bond interactions in high lignin solubilization and valorization.

  3. An EPR investigation of room temperature radiation damage and molecular motion in the ferroelectric phosphates

    International Nuclear Information System (INIS)

    Dalal, N.S.; Herak, J.N.; McDowell, C.A.

    1976-01-01

    Several types of paramagnetic centers have been detected in the room temperature irradiated KH 2 PO 4 , KD 2 PO 4 , KH 2 PO 4 -KH 2 AsO 4 , KD 2 PO 4 -KD 2 AsO 4 and in the newly discovered ferroelectric NaTh 2 (PO 4 ) 3 . Comparative studies of temperature dependence in the EPR spectra show that as in KH 2 PO 4 -type crystals, the ferroelectric phase transition in NaTh 2 (PO 4 ) 3 crystals also seems to be related to the motion of the PO 4 units. The results help to clarify some earlier observed anomalies on the effects of γ-irradiation on dielectric properties of KH 2 PO 4 and in particular, show that the extent of the damage can be controlled by changing the impurity content of the unirradiated samples. (Auth.)

  4. Complex hydrides as room-temperature solid electrolytes for rechargeable batteries

    DEFF Research Database (Denmark)

    Jongh, P. E. de; Blanchard, D.; Matsuo, M.

    2016-01-01

    with Li-metal anodes, prevent Li dendrite formation, and eliminate risks associated with flammable organic solvents. Less than 10 years ago, LiBH4 was proposed as a solid-state electrolyte. It showed a high ionic conductivity, but only at elevated temperatures. Since then a range of other complex metal......A central goal in current battery research is to increase the safety and energy density of Li-ion batteries. Electrolytes nowadays typically consist of lithium salts dissolved in organic solvents. Solid electrolytes could facilitate safer batteries with higher capacities, as they are compatible...... hydrides has been reported to show similar characteristics. Strategies have been developed to extend the high ionic conductivity of LiBH4 down to room temperature by partial anion substitution or nanoconfinement. The present paper reviews the recent developments in complex metal hydrides as solid...

  5. Iron-aluminum alloys having high room-temperature and method for making same

    Science.gov (United States)

    Sikka, V.K.; McKamey, C.G.

    1993-08-24

    A wrought and annealed iron-aluminum alloy is described consisting essentially of 8 to 9.5% aluminum, an effective amount of chromium sufficient to promote resistance to aqueous corrosion of the alloy, and an alloying constituent selected from the group of elements consisting of an effective amount of molybdenum sufficient to promote solution hardening of the alloy and resistance of the alloy to pitting when exposed to solutions containing chloride, up to about 0.05% carbon with up to about 0.5% of a carbide former which combines with the carbon to form carbides for controlling grain growth at elevated temperatures, and mixtures thereof, and the balance iron, wherein said alloy has a single disordered [alpha] phase crystal structure, is substantially non-susceptible to hydrogen embrittlement, and has a room-temperature ductility of greater than 20%.

  6. Numerical modelling and analysis of a room temperature magnetic refrigeration system

    DEFF Research Database (Denmark)

    Petersen, Thomas Frank

    This thesis presents a two-dimensional mathematical model of an Active Magnetic Regenerator (AMR) system which is used for magnetic refrigeration at room temperature. The purpose of the model is to simulate a laboratory-scale AMR constructed at Risø National Laboratory. The AMR model geometry...... comprises a regenerator made of parallel plates, which are separated by channels of a heat transfer fluid. The time-dependent model solves the momentum and continuity equations of the flow of the heat transfer fluid and the coupled energy equations of the heat transfer in the regenerator and the fluid...... of the chosen grid and time step. Initial results from the model showed significant temperature differences in both the regenerator and the fluid channel during the AMR cycle. This justifies the use of two-dimensional methods when an AMR with a parallel-plate regenerator is modelled. The model is flexible...

  7. Size effect studies on smooth tensile specimens at room temperature and 400 {sup o}C

    Energy Technology Data Exchange (ETDEWEB)

    Krompholz, K.; Kamber, J.; Groth, E.; Kalkhof, D

    2000-06-15

    One of the objectives of the REVISA project (REactor Vessel Integrity in Severe Accidents) is to assess the size effect related to deformation and failure models as well as material data under quasistatic and dynamic conditions in homogeneous and non-homogeneous states of strain. For these investigations the reactor pressure vessel material 20 MnMoNi 55 was selected. It was subjected to a size effect study on smooth scaled tensile specimens of three sizes. Two strain rates (2*10{sup -5}/s and 10{sup -3}/s) and two temperatures (room temperature and 400 {sup o}C) were selected. The investigations are aimed at a support for a gradient plasticity approach to size effects. Test on the small specimens (diameters 3 and 9 mm) were performed at an electromechanical test machine, while the large specimens (diameter 30 mm) had to be tested at a servohydraulical closed loop test machine with a force capacity of 1000 kN.

  8. Surface induces different crystal structures in a room temperature switchable spin crossover compound.

    Science.gov (United States)

    Gentili, Denis; Liscio, Fabiola; Demitri, Nicola; Schäfer, Bernhard; Borgatti, Francesco; Torelli, Piero; Gobaut, Benoit; Panaccione, Giancarlo; Rossi, Giorgio; Degli Esposti, Alessandra; Gazzano, Massimo; Milita, Silvia; Bergenti, Ilaria; Ruani, Giampiero; Šalitroš, Ivan; Ruben, Mario; Cavallini, Massimiliano

    2016-01-07

    We investigated the influence of surfaces in the formation of different crystal structures of a spin crossover compound, namely [Fe(L)2] (LH: (2-(pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine), which is a neutral compound thermally switchable around room temperature. We observed that the surface induces the formation of two different crystal structures, which exhibit opposite spin transitions, i.e. on heating them up to the transition temperature, one polymorph switches from high spin to low spin and the second polymorph switches irreversibly from low spin to high spin. We attributed this inversion to the presence of water molecules H-bonded to the complex tetrazolyl moieties in the crystals. Thin deposits were investigated by means of polarized optical microscopy, atomic force microscopy, X-ray diffraction, X-ray absorption spectroscopy and micro Raman spectroscopy; moreover the analysis of the Raman spectra and the interpretation of spin inversion were supported by DFT calculations.

  9. On the thermodynamic path enabling a room-temperature, laser-assisted graphite to nanodiamond transformation

    Science.gov (United States)

    Gorrini, F.; Cazzanelli, M.; Bazzanella, N.; Edla, R.; Gemmi, M.; Cappello, V.; David, J.; Dorigoni, C.; Bifone, A.; Miotello, A.

    2016-10-01

    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 provides a confinement mechanism that promotes diamond nucleation and growth, and a biologically compatible medium for suspension of nanodiamonds. Moreover, we introduce a facile physico-chemical method that does not require harsh chemical or temperature conditions to remove the graphitic byproducts of the laser ablation process. A full characterization of the nanodiamonds by electron and Raman spectroscopies is reported. Our model is also corroborated by comparison with experimental data from the literature.

  10. Microstructure evolution during cyclic tests on EUROFER 97 at room temperature. TEM observation and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Giordana, M.F., E-mail: giordana@ifir-conicet.gov.ar [Instituto de Fisica Rosario, CONICET-UNR, Bv. 27 de Febrero 210 Bis, 2000 Rosario (Argentina); Giroux, P.-F. [Commissariat a l' Energie Atomique, DEN/DANS/DMN/SRMA, 91191 Gif-sur-Yvette Cedex (France); Alvarez-Armas, I. [Instituto de Fisica Rosario, CONICET-UNR, Bv. 27 de Febrero 210 Bis, 2000 Rosario (Argentina); Sauzay, M. [Commissariat a l' Energie Atomique, DEN/DANS/DMN/SRMA, 91191 Gif-sur-Yvette Cedex (France); Armas, A. [Instituto de Fisica Rosario, CONICET-UNR, Bv. 27 de Febrero 210 Bis, 2000 Rosario (Argentina); Kruml, T. [CEITEC IPM, Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, Brno, 616 62 (Czech Republic)

    2012-07-30

    Highlights: Black-Right-Pointing-Pointer Low cycle fatigue test are carried out on EUROFER 97 at room temperature. Black-Right-Pointing-Pointer EUROFER 97 shows a pronounced cyclic softening accompanied by microstructural changes. Black-Right-Pointing-Pointer Cycling induces a decrement in dislocation density and subgrain growth. Black-Right-Pointing-Pointer A simple mean-field model based on crystalline plasticity is proposed. Black-Right-Pointing-Pointer The mean subgrain size evolution is predicted by modelling. - Abstract: The 9% Cr quenched and tempered reduced-activation ferritic/martensitic steel EUROFER 97 is one of the candidates for structural components of fusion reactors. Isothermal, plastic strain-controlled, low-cycle fatigue tests are performed. Tested at room temperature, this steel suffers a cyclic softening effect linked to microstructural changes observed by transmission electron microscopy, such as the decrease of dislocation density inside subgrains or the growth of subgrain size. From the assumed mechanisms of softening a simple mean-field model based on crystalline plasticity is proposed to predict these microstructure evolutions during cycling and monotonic deformation.

  11. Room-temperature treatments for all-inorganic nanocrystal solar cell devices

    Energy Technology Data Exchange (ETDEWEB)

    Loiudice, Anna, E-mail: anna.loiudice@iit.it [Dipartimento di Matematica e Fisica " E. De Giorgi" , Università del Salento, via Arnesano, 73100 Lecce (Italy); CBN — Center for Biomolecular Nanotechnologies, Italian Institute of Technology, Energy Platform, Via Barsanti sn, 73010 Arnesano (Lecce) (Italy); Rizzo, Aurora [CBN — Center for Biomolecular Nanotechnologies, Italian Institute of Technology, Energy Platform, Via Barsanti sn, 73010 Arnesano (Lecce) (Italy); NNL CNR-Istituto Nanoscienze, c/o Distretto Tecnologico, via per Arnesano km. 5, 73100 Lecce (Italy); Corricelli, Michela [Istituto per i Processi Chimico Fisici (IPCF-CNR) Bari, c/o Department of Chemistry, University of Bari, Via Orabona 4, I-70126 Bari (Italy); Department of Chemistry, University of Bari, Via Orabona 4, I-70126 Bari (Italy); Curri, M. Lucia [Istituto per i Processi Chimico Fisici (IPCF-CNR) Bari, c/o Department of Chemistry, University of Bari, Via Orabona 4, I-70126 Bari (Italy); Belviso, Maria R. [NNL CNR-Istituto Nanoscienze, c/o Distretto Tecnologico, via per Arnesano km. 5, 73100 Lecce (Italy); Cozzoli, P. Davide [Dipartimento di Matematica e Fisica " E. De Giorgi" , Università del Salento, via Arnesano, 73100 Lecce (Italy); NNL CNR-Istituto Nanoscienze, c/o Distretto Tecnologico, via per Arnesano km. 5, 73100 Lecce (Italy); Grancini, Giulia; Petrozza, Annamaria [Center for Nano Science and Technology at PoliMi, Istituto Italiano di Tecnologia, Via Pascoli 70/3, 20133 Milano (Italy); Gigli, Giuseppe [Dipartimento di Matematica e Fisica " E. De Giorgi" , Università del Salento, via Arnesano, 73100 Lecce (Italy); CBN — Center for Biomolecular Nanotechnologies, Italian Institute of Technology, Energy Platform, Via Barsanti sn, 73010 Arnesano (Lecce) (Italy); NNL CNR-Istituto Nanoscienze, c/o Distretto Tecnologico, via per Arnesano km. 5, 73100 Lecce (Italy)

    2014-06-02

    We have developed a room-temperature solution processing approach to integrate colloidal anatase titanium dioxide nanorods (TiO{sub 2} NRs) and lead sulfide quantum dots (PbS QDs) into a heterostructured p-n junction device. To this aim we have exploited a post-deposition treatment to remove surface-adsorbed ligands by means of UV-light-irradiation of TiO{sub 2} NRs and a dilute acid treatment of PbS QDs. Here we report a systematic study on the optimization of the post-deposition treatments and device fabrication. Our approach is fully compatible with plastic device technology and is potentially useful for the integration of crystalline TiO{sub 2} as active component into disparate solar cell architectures and organic optoelectronic devices. - Highlights: • Colloidal nanocrystals offer path to low-cost manufacturing atop flexible substrates. • We fabricate an all-inorganic solar cell under room temperature treatments. • Our approach is fully compatible with plastic device technology. • It is useful for the integration of nanocrystals into disparate device architectures.

  12. Room-temperature negative capacitance in a ferroelectric-dielectric superlattice heterostructure.

    Science.gov (United States)

    Gao, Weiwei; Khan, Asif; Marti, Xavi; Nelson, Chris; Serrao, Claudy; Ravichandran, Jayakanth; Ramesh, Ramamoorthy; Salahuddin, Sayeef

    2014-10-08

    We demonstrate room-temperature negative capacitance in a ferroelectric-dielectric superlattice heterostructure. In epitaxially grown superlattice of ferroelectric BSTO (Ba0.8Sr0.2TiO3) and dielectric LAO (LaAlO3), capacitance was found to be larger compared to the constituent LAO (dielectric) capacitance. This enhancement of capacitance in a series combination of two capacitors indicates that the ferroelectric was stabilized in a state of negative capacitance. Negative capacitance was observed for superlattices grown on three different substrates (SrTiO3 (001), DyScO3 (110), and GdScO3 (110)) covering a large range of substrate strain. This demonstrates the robustness of the effect as well as potential for controlling the negative capacitance effect using epitaxial strain. Room-temperature demonstration of negative capacitance is an important step toward lowering the subthreshold swing in a transistor below the intrinsic thermodynamic limit of 60 mV/decade and thereby improving energy efficiency.

  13. Metal-Controlled Magnetoresistance at Room Temperature in Single-Molecule Devices.

    Science.gov (United States)

    Aragonès, Albert C; Aravena, Daniel; Valverde-Muñoz, Francisco J; Real, José Antonio; Sanz, Fausto; Díez-Pérez, Ismael; Ruiz, Eliseo

    2017-04-26

    The appropriate choice of the transition metal complex and metal surface electronic structure opens the possibility to control the spin of the charge carriers through the resulting hybrid molecule/metal spinterface in a single-molecule electrical contact at room temperature. The single-molecule conductance of a Au/molecule/Ni junction can be switched by flipping the magnetization direction of the ferromagnetic electrode. The requirements of the molecule include not just the presence of unpaired electrons: the electronic configuration of the metal center has to provide occupied or empty orbitals that strongly interact with the junction metal electrodes and that are close in energy to their Fermi levels for one of the electronic spins only. The key ingredient for the metal surface is to provide an efficient spin texture induced by the spin-orbit coupling in the topological surface states that results in an efficient spin-dependent interaction with the orbitals of the molecule. The strong magnetoresistance effect found in this kind of single-molecule wire opens a new approach for the design of room-temperature nanoscale devices based on spin-polarized currents controlled at molecular level.

  14. Possible room temperature ferromagnetism in Ca-doped AlP: First-principles study

    International Nuclear Information System (INIS)

    Zhang, Yong

    2013-01-01

    Based on first-principle calculations, we have studied the electronic and magnetic properties of AlP with aluminium vacancy and calcium doping. It was found that while Al vacancy and Ca impurity themselves are nonmagnetic, they generate holes residing in P 2p orbitals that lead to magnetic moments in AlP. The coupling between two Al vacancies in AlP are always antiferromagnetic because of half-filled t 2 level. However, the coupling becomes ferromagnetic with large magnetic energy when vacancies are replaced by nonmagnetic Ca atoms. Moreover, the presence of Ca dopants reduces the formation energy of Al vacancy. These results suggest that Ca-doped AlP is a promising room temperature ferromagnetic semiconductor free of magnetic precipitates, and it may find applications in the field of spintronics. - Highlights: • “d 0 ferromagnetism” has been found in Ca-doped AlP. • Unpaired t 2 state of P atoms has an important impact on magnetic properties. • Room temperature T C may be expected in Ca-doped AlP

  15. Molecular dynamics study of room temperature ionic liquids with water at mica surface

    Directory of Open Access Journals (Sweden)

    Huanhuan Zhang

    2018-04-01

    Full Text Available Water in room temperature ionic liquids (RTILs could impose significant effects on their interfacial properties at a charged surface. Although the interfaces between RTILs and mica surfaces exhibit rich microstructure, the influence of water content on such interfaces is little understood, in particular, considering the fact that RTILs are always associated with water due to their hygroscopicity. In this work, we studied how different types of RTILs and different amounts of water molecules affect the RTIL-mica interfaces, especially the water distribution at mica surfaces, using molecular dynamics (MD simulation. MD results showed that (1 there is more water and a thicker water layer adsorbed on the mica surface as the water content increases, and correspondingly the average location of K+ ions is farther from mica surface; (2 more water accumulated at the interface with the hydrophobic [Emim][TFSI] than in case of the hydrophilic [Emim][BF4] due to the respective RTIL hydrophobicity and ion size. A similar trend was also observed in the hydrogen bonds formed between water molecules. Moreover, the 2D number density map of adsorbed water revealed that the high-density areas of water seem to be related to K+ ions and silicon/aluminum atoms on mica surface. These results are of great importance to understand the effects of hydrophobicity/hydrophicility of RTIL and water on the interfacial microstructure at electrified surfaces. Keywords: Room temperature ionic liquids, Hydrophobicity/hydrophicility, Water content, Electrical double layer, Mica surface

  16. Room-Temperature-Processed Flexible Amorphous InGaZnO Thin Film Transistor.

    Science.gov (United States)

    Xiao, Xiang; Zhang, Letao; Shao, Yang; Zhou, Xiaoliang; He, Hongyu; Zhang, Shengdong

    2017-12-13

    A room-temperature flexible amorphous indium-gallium-zinc oxide thin film transistor (a-IGZO TFT) technology is developed on plastic substrates, in which both the gate dielectric and passivation layers of the TFTs are formed by an anodic oxidation (anodization) technique. While the gate dielectric Al 2 O 3 is grown with a conventional anodization on an Al:Nd gate electrode, the channel passivation layer Al 2 O 3 is formed using a localized anodization technique. The anodized Al 2 O 3 passivation layer shows a superior passivation effect to that of PECVD SiO 2 . The room-temperature-processed flexible a-IGZO TFT exhibits a field-effect mobility of 7.5 cm 2 /V·s, a subthreshold swing of 0.44 V/dec, an on-off ratio of 3.1 × 10 8 , and an acceptable gate-bias stability with threshold voltage shifts of 2.65 and -1.09 V under positive gate-bias stress and negative gate-bias stress, respectively. Bending and fatigue tests confirm that the flexible a-IGZO TFT also has a good mechanical reliability, with electrical performances remaining consistent up to a strain of 0.76% as well as after 1200 cycles of fatigue testing.

  17. Preparation and Extraordinary Room-Temperature CO Sensing Capabilities of Pd-SnO₂ Composite Nanoceramics.

    Science.gov (United States)

    Wang, Mengye; Sun, Beilei; Jiang, Zhengyong; Liu, Yong; Wang, Xuening; Tang, Zilong; Wang, Yu; Chen, Wanping

    2018-06-01

    Pd-SnO2 composite nanoceramics have been prepared from SnO2 and Pd nanoparticles through traditional pressing and sintering. Their responses to CO at room temperature are found to depend greatly on the content of Pd. For those samples with 1.0 and 5.0 mol% Pd, their resistance increases dramatically upon being exposed to CO in air; while for samples of 0.2 mol% Pd, their resistance decreases greatly upon being exposed to CO in air, and extraordinary room-temperature CO sensing capabilities, including high sensitivities around 15, short response time of 20 s and recovery time of 60 s for 100 ppm CO in air, a high selectivity against H2, have been observed for them. X-ray photoelectron spectroscopy analyses showed that Pd2+ was formed in samples of 1 mol% Pd, while both Pd2+ and Pd4+ were formed in samples of 0.2 mol% Pd. It is proposed that for Pd-SnO2 composite nanoceramics, Pd2+ is responsible for CO-induced increase while Pd4+ is responsible for CO-induced decrease in resistance.

  18. γ-irradiation induced zinc ferrites and their enhanced room-temperature ammonia gas sensing properties

    Science.gov (United States)

    Raut, S. D.; Awasarmol, V. V.; Ghule, B. G.; Shaikh, S. F.; Gore, S. K.; Sharma, R. P.; Pawar, P. P.; Mane, R. S.

    2018-03-01

    Zinc ferrite (ZnFe2O4) nanoparticles (NPs), synthesized using a facile and cost-effective sol-gel auto-combustion method, were irradiated with 2 and 5 kGy γ-doses using 60Co as a radioactive source. Effect of γ-irradiation on the structure, morphology, pore-size and pore-volume and room-temperature (300 K) gas sensor performance has been measured and reported. Both as-synthesized and γ-irradiated ZnFe2O4 NPs reveal remarkable gas sensor activity to ammonia in contrast to methanol, ethanol, acetone and toluene volatile organic gases. The responses of pristine, 2 and 5 kGy γ-irradiated ZnFe2O4 NPs are respectively 55%, 66% and 81% @100 ppm concentration of ammonia, signifying an importance of γ-irradiation for enhancing the sensitivity, selectivity and stability of ZnFe2O4 NPs as ammonia gas sensors. Thereby, due to increase in surface area and crystallinity on γ-doses, the γ-irradiation improves the room-temperature ammonia gas sensing performance of ZnFe2O4.

  19. Self-assembly of gas-phase synthesized magnesium nanoparticles on room temperature substrates

    Science.gov (United States)

    Venturi, F.; Calizzi, M.; Bals, S.; Perkisas, T.; Pasquini, L.

    2015-01-01

    Magnesium nanoparticles (NPs) with initial size in the 10-50 nm range were synthesized by inert gas condensation under helium flow and deposited on room temperature substrates. The morphology and crystal structure of the NPs ensemble were investigated as a function of the deposition time by complementary electron microscopy techniques, including high resolution imaging and chemical mapping. With increasing amount of material, strong coarsening phenomena were observed at room temperature: small NPs disappeared while large faceted NPs developed, leading to a 5-fold increase of the average NPs size within a few minutes. The extent of coarsening and the final morphology depended also on the nature of the substrate. Furthermore, large single-crystal NPs were seen to arise from the self-organization of primary NPs units, providing a mechanism for crystal growth. The dynamics of the self-assembly process involves the basic steps of NPs sticking, diffusion on substrate, coordinated rotation and attachment/coalescence. Key features are the surface energy anisotropy, reflected by the faceted shape of the NPs, and the low melting point of the material. The observed phenomena have strong implications in relation to the synthesis and stability of nanostructures based on Mg or other elements with similar features.

  20. Giant room-temperature magnetodielectric coupling in spark plasma sintered brownmillerite ceramics

    International Nuclear Information System (INIS)

    Wu, J. W.; Wang, J.; Liu, G.; Wu, Y. J.; Liu, X. Q.; Chen, X. M.

    2014-01-01

    The dielectric, magnetic, and magnetodielectric properties of Ca 2 FeAO 5+δ (A = Al, Ga) ceramics were investigated together with their crystal structures. Rietveld refinement of the X-ray diffraction data indicated that the space group of the Ca 2 FeAlO 5+δ ceramic was Ibm2, whereas that of the Ca 2 FeGaO 5+δ ceramic was Pcmn. Dielectric relaxation above room temperature, originating from the Maxwell–Wagner effect and polaronic hole hopping between Fe 3+ and Fe 4+ ions, was observed in both ceramics. Weak ferrimagnetic behavior was identified from the magnetic-field-dependent magnetization in these ceramics, which was attributed to the non-cancelled spins of the antiferromagnetic-ordered Fe 3+ and Fe 4+ ions. An intrinsic, giant, room-temperature magnetodielectric coefficient of up to −23.3% was achieved in the Ca 2 FeAlO 5+δ ceramic at 50 MHz, which was attributed to the suppression of charge fluctuations of Fe 3+ and Fe 4+ ions in the magnetic field

  1. A Room Temperature Ultrasensitive Magnetoelectric Susceptometer for Quantitative Tissue Iron Detection

    Science.gov (United States)

    Xi, Hao; Qian, Xiaoshi; Lu, Meng-Chien; Mei, Lei; Rupprecht, Sebastian; Yang, Qing X.; Zhang, Q. M.

    2016-07-01

    Iron is a trace mineral that plays a vital role in the human body. However, absorbing and accumulating excessive iron in body organs (iron overload) can damage or even destroy an organ. Even after many decades of research, progress on the development of noninvasive and low-cost tissue iron detection methods is very limited. Here we report a recent advance in a room-temperature ultrasensitive biomagnetic susceptometer for quantitative tissue iron detection. The biomagnetic susceptometer exploits recent advances in the magnetoelectric (ME) composite sensors that exhibit an ultrahigh AC magnetic sensitivity under the presence of a strong DC magnetic field. The first order gradiometer based on piezoelectric and magnetostrictive laminate (ME composite) structure shows an equivalent magnetic noise of 0.99 nT/rt Hz at 1 Hz in the presence of a DC magnetic field of 0.1 Tesla and a great common mode noise rejection ability. A prototype magnetoelectric liver susceptometry has been demonstrated with liver phantoms. The results indicate its output signals to be linearly responsive to iron concentrations from normal iron dose (0.05 mg Fe/g liver phantom) to 5 mg Fe/g liver phantom iron overload (100X overdose). The results here open up many innovative possibilities for compact-size, portable, cost-affordable, and room-temperature operated medical systems for quantitative determinations of tissue iron.

  2. Room temperature high-detectivity mid-infrared photodetectors based on black arsenic phosphorus.

    Science.gov (United States)

    Long, Mingsheng; Gao, Anyuan; Wang, Peng; Xia, Hui; Ott, Claudia; Pan, Chen; Fu, Yajun; Liu, Erfu; Chen, Xiaoshuang; Lu, Wei; Nilges, Tom; Xu, Jianbin; Wang, Xiaomu; Hu, Weida; Miao, Feng

    2017-06-01

    The mid-infrared (MIR) spectral range, pertaining to important applications, such as molecular "fingerprint" imaging, remote sensing, free space telecommunication, and optical radar, is of particular scientific interest and technological importance. However, state-of-the-art materials for MIR detection are limited by intrinsic noise and inconvenient fabrication processes, resulting in high-cost photodetectors requiring cryogenic operation. We report black arsenic phosphorus-based long-wavelength IR photodetectors, with room temperature operation up to 8.2 μm, entering the second MIR atmospheric transmission window. Combined with a van der Waals heterojunction, room temperature-specific detectivity higher than 4.9 × 10 9 Jones was obtained in the 3- to 5-μm range. The photodetector works in a zero-bias photovoltaic mode, enabling fast photoresponse and low dark noise. Our van der Waals heterojunction photodetectors not only exemplify black arsenic phosphorus as a promising candidate for MIR optoelectronic applications but also pave the way for a general strategy to suppress 1/ f noise in photonic devices.

  3. Photocatalytic reduction of NO pollutant using an optical-fibre photoreactor at room temperature.

    Science.gov (United States)

    Yu, Yi-Hui; Su, I-Hsuan; Wu, Jeffrey C S

    2010-12-01

    Photo-assisted catalytic reduction of nitric oxide (NO) was studied over different metal-loaded TiO2 catalysts at room temperature. The activities of metal-loaded (Pt, Ag, Cu) TiO2 photocatalysts, prepared by the sol-gel method, were compared in a batch system using CH4 as the reducing agent. The Pt/TiO2 catalyst showed the highest activity for NO reduction. Thus, Pt/TiO2 was coated on optical fibres and used in a continuous-flow optical-fibre photoreactor. The optical-fibre photoreactor provides light irradiation on the photocatalyst through the optical fibre, thus improving the efficiency ofphotoreactions. Ten per cent conversion of NO was found using CH4 as the reducing agent. The NO conversions increased to 90% in the presence of water vapour and oxygen. However, most NO was oxidized to NO2. Hydrogen had superior reducing capabilities over CH4 on Pt/TiO2 photocatalyst, and the conversion of NO reached 85%. But the conversion of NO was substantially decreased to less than 10% in the presence of water vapour and oxygen. Our research proposed an alternative way to reduce NO pollutant to N2 at room temperature using an optical-fibre photoreactor, which could possibly utilize sunlight in the future.

  4. Room-temperature near-infrared high-Q perovskite whispering-gallery planar nanolasers.

    Science.gov (United States)

    Zhang, Qing; Ha, Son Tung; Liu, Xinfeng; Sum, Tze Chien; Xiong, Qihua

    2014-10-08

    Near-infrared (NIR) solid-state micro/nanolasers are important building blocks for true integration of optoelectronic circuitry. Although significant progress has been made in III-V nanowire lasers with achieving NIR lasing at room temperature, challenges remain including low quantum efficiencies and high Auger losses. Importantly, the obstacles toward integrating one-dimensional nanowires on the planar ubiquitous Si platform need to be effectively tackled. Here we demonstrate a new family of planar room-temperature NIR nanolasers based on organic-inorganic perovskite CH3NH3PbI(3-a)X(a) (X = I, Br, Cl) nanoplatelets. Their large exciton binding energies, long diffusion lengths, and naturally formed high-quality planar whispering-gallery mode cavities ensure adequate gain and efficient optical feedback for low-threshold optically pumped in-plane lasing. We show that these remarkable wavelength tunable whispering-gallery nanolasers can be easily integrated onto conductive platforms (Si, Au, indium tin oxide, and so forth). Our findings open up a new class of wavelength tunable planar nanomaterials potentially suitable for on-chip integration.

  5. Room Temperature Cyclic Deformation Behavior of Cast and Extruded NiAl

    Science.gov (United States)

    Noebe, R. D.; Lerch, B. A.

    1992-01-01

    The fully reversed, strain controlled fatigue behavior of cast and extruded NiAl was evaluated at room temperature for plastic strain ranges of 0.0006 to 0.0002 to provide baseline data on the fatigue life of NiAl and to investigate whether the low ductility of NiAl would result in poor low-cycle fatigue behavior. Except at the smallest plastic strain range investigated, NiAl work hardened continuously until failure with a final fracture stress under cyclic conditions which was at least 60 percent greater than the monotonic fracture strength of NiAl. Fatigue fracture initiation occurred at large internal tear-shaped pores, and fatigue life was controlled or limited by the presence of these processing-related defects. Even with the processing defects present in this material and the limited ductility of NiAl in general, cast and extruded NiAl exhibited much greater fatigue life at room temperature than comparable B2 ordered compounds when compared on a strain range basis.

  6. Room temperature diamond-like carbon coatings produced by low energy ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Markwitz, A., E-mail: a.markwitz@gns.cri.nz [Department for Ion Beam Technologies, GNS Science, 30 Gracefield Road, Lower Hutt (New Zealand); The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Mohr, B.; Leveneur, J. [Department for Ion Beam Technologies, GNS Science, 30 Gracefield Road, Lower Hutt (New Zealand)

    2014-07-15

    Nanometre-smooth diamond-like carbon coatings (DLC) were produced at room temperature with ion implantation using 6 kV C{sub 3}H{sub y}{sup +} ion beams. Ion beam analysis measurements showed that the coatings contain no heavy Z impurities at the level of 100 ppm, have a homogeneous stoichiometry in depth and a hydrogen concentration of typically 25 at.%. High resolution TEM analysis showed high quality and atomically flat amorphous coatings on wafer silicon. Combined TEM and RBS analysis gave a coating density of 3.25 g cm{sup −3}. Raman spectroscopy was performed to probe for sp{sup 2}/sp{sup 3} bonds in the coatings. The results indicate that low energy ion implantation with 6 kV produces hydrogenated amorphous carbon coatings with a sp{sup 3} content of about 20%. Results highlight the opportunity of developing room temperature DLC coatings with ion beam technology for industrial applications.

  7. Hydrogen Treatment for Superparamagnetic VO2 Nanowires with Large Room-Temperature Magnetoresistance.

    Science.gov (United States)

    Li, Zejun; Guo, Yuqiao; Hu, Zhenpeng; Su, Jihu; Zhao, Jiyin; Wu, Junchi; Wu, Jiajing; Zhao, Yingcheng; Wu, Changzheng; Xie, Yi

    2016-07-04

    One-dimensional (1D) transition metal oxide (TMO) nanostructures are actively pursued in spintronic devices owing to their nontrivial d electron magnetism and confined electron transport pathways. However, for TMOs, the realization of 1D structures with long-range magnetic order to achieve a sensitive magnetoelectric response near room temperature has been a longstanding challenge. Herein, we exploit a chemical hydric effect to regulate the spin structure of 1D V-V atomic chains in monoclinic VO2 nanowires. Hydrogen treatment introduced V(3+) (3d(2) ) ions into the 1D zigzag V-V chains, triggering the formation of ferromagnetically coupled V(3+) -V(4+) dimers to produce 1D superparamagnetic chains and achieve large room-temperature negative magnetoresistance (-23.9 %, 300 K, 0.5 T). This approach offers new opportunities to regulate the spin structure of 1D nanostructures to control the intrinsic magnetoelectric properties of spintronic materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Observation of Room-Temperature Magnetoresistance in Monolayer MoS2 by Ferromagnetic Gating.

    Science.gov (United States)

    Jie, Wenjing; Yang, Zhibin; Zhang, Fan; Bai, Gongxun; Leung, Chi Wah; Hao, Jianhua

    2017-07-25

    Room-temperature magnetoresistance (MR) effect is observed in heterostructures of wafer-scale MoS 2 layers and ferromagnetic dielectric CoFe 2 O 4 (CFO) thin films. Through the ferromagnetic gating, an MR ratio of -12.7% is experimentally achieved in monolayer MoS 2 under 90 kOe magnetic field at room temperature (RT). The observed MR ratio is much higher than that in previously reported nonmagnetic metal coupled with ferromagnetic insulator, which generally exhibited MR ratio of less than 1%. The enhanced MR is attributed to the spin accumulation at the heterostructure interface and spin injection to the MoS 2 layers by the strong spin-orbit coupling effect. The injected spin can contribute to the spin current and give rise to the MR by changing the resistance of MoS 2 layers. Furthermore, the MR effect decreases as the thickness of MoS 2 increases, and the MR ratio becomes negligible in MoS 2 with thickness more than 10 layers. Besides, it is interesting to find a magnetic field direction dependent spin Hall magnetoresistance that stems from a combination of the spin Hall and the inverse spin Hall effects. Our research provides an insight into exploring RT MR in monolayer materials, which should be helpful for developing ultrathin magnetic storage devices in the atomically thin limit.

  9. Real-time transmission electron microscope observation of gold nanoclusters diffusing into silicon at room temperature

    International Nuclear Information System (INIS)

    Ishida, Tadashi; Nakajima, Yuuki; Fujita, Hiroyuki; Endo, Junji; Collard, Dominique

    2009-01-01

    Gold diffusion into silicon at room temperature was observed in real time with atomic resolution. Gold nanoclusters were formed on a silicon surface by an electrical discharge between a silicon tip and a gold coated tip inside an ultrahigh-vacuum transmission electron microscope (TEM) specimen chamber. At the moment of the gold nanocluster deposition, the gold nanoclusters had a crystalline structure. The crystalline structure gradually disappeared due to the interdiffusion between silicon and gold as observed after the deposition of gold nanoclusters. The shape of the nanocluster gradually changed due to the gold diffusion into the damaged silicon. The diffusion front between silicon and gold moved toward the silicon side. From the observations of the diffusion front, the gold diffusivity at room temperature was extracted. The extracted activation energy, 0.21 eV, matched the activation energy in bulk diffusion between damaged silicon and gold. This information is useful for optimizing the hybridization between solid-state and biological nanodevices in which gold is used as an adhesive layer between the two devices.

  10. Fabrication and Microstructure of Hydroxyapatite Coatings on Zirconia by Room Temperature Spray Process.

    Science.gov (United States)

    Seo, Dong Seok; Chae, Hak Cheol; Lee, Jong Kook

    2015-08-01

    Hydroxyapatite coatings were fabricated on zirconia substrates by a room temperature spray process and were investigated with regards to their microstructure, composition and dissolution in water. An initial hydroxyapatite powder was prepared by heat treatment of bovine-bone derived powder at 1100 °C for 2 h, while dense zirconia substrates were fabricated by pressing 3Y-TZP powder and sintering it at 1350 °C for 2 h. Room temperature spray coating was performed using a slit nozzle in a low pressure-chamber with a controlled coating time. The phase composition of the resultant hydroxyapatite coatings was similar to that of the starting powder, however, the grain size of the hydroxyapatite particles was reduced to about 100 nm due to their formation by particle impaction and fracture. All areas of the coating had a similar morphology, consisting of reticulated structure with a high surface roughness. The hydroxyapatite coating layer exhibited biostability in a stimulated body fluid, with no severe dissolution being observed during in vitro experimentation.

  11. Room temperature deformation of in-situ grown quasicrystals embedded in Al-based cast alloy

    Directory of Open Access Journals (Sweden)

    Boštjan Markoli

    2013-12-01

    Full Text Available An Al-based cast alloy containing Mn, Be and Cu has been chosen to investigate the room temperature deformation behavior of QC particles embedded in Al-matrix. Using LOM, SEM (equipped with EDS, conventional TEM with SAED and controlled tensile and compression tests, the deformation response of AlMn2Be2Cu2 cast alloy at room temperature has been examined. Alloy consisted of Al-based matrix, primary particles and eutectic icosahedral quasicrystalline (QC i-phase and traces of Θ-Al2Cu and Al10Mn3. Tensile and compression specimens were used for evaluation of mechanical response and behavior of QC i-phase articles embedded in Al-cast alloy. It has been established that embedded QC i-phase particles undergo plastic deformation along with the Al-based matrix even under severe deformation and have the response resembling that of the metallic materials by formation of typical cup-and-cone feature prior to failure. So, we can conclude that QC i-phase has the ability to undergo plastic deformation along with the Al-matrix to greater extent contrary to e.g. intermetallics such as Θ-Al2Cu for instance.

  12. Room temperature synthesis of a Zn(II) metal-organic coordination polymer for dye removal

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Alireza, E-mail: aabbasi@khayam.ut.ac.ir [School of Chemistry, College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Gharib, Maniya; Najafi, Mahnaz [School of Chemistry, College of Science, University of Tehran, Tehran (Iran, Islamic Republic of); Janczak, Jan [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, PO Box 1410, 50-950 Wrocław (Poland)

    2016-03-15

    A new one-dimensional (1D) coordination polymer, [Zn(4,4′-bpy)(H{sub 2}O){sub 4}](ADC)·4H{sub 2}O (1) (4,4′-bpy=4,4′-bipyridine and H{sub 2}ADC=acetylenedicarboxylic acid), was synthesized at room temperature. The crystal structure of the coordination polymer was determined by single-crystal X-ray diffraction analysis. Compound 1 was also characterized by FT-IR, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). The catalytic activity of 1 was evaluated in the color removal of Bismarck brown as a representative of dye pollutant in water under mild conditions. Coordination polymer 1 exhibited good catalytic activity and stability in the decolorization of Bismarck brown and could be easily recovered and reused for at least three cycles. - Graphical abstract: A new 1D coordination polymer as catalyst for the degradation of Bismarck brown aqueous solution. - Highlights: • A 1D coordination polymer has been synthesized at room temperature. • The prepared compound was utilized for color removal of Bismarck brown dye. • Good catalytic activity and stability in the dye decolorization has been found.

  13. Ferromagnetism at room temperature in Co-doped KNbO{sub 3} bulk samples

    Energy Technology Data Exchange (ETDEWEB)

    Astudillo, A., E-mail: jaastudillo@unicauca.edu.co [Low Temperature Laboratory, Department of Physics, University of Cauca, Calle 5 No. 4-70, Popayán (Colombia); Izquierdo, J.L. [Universidad Nacional de Colombia, Campus Medellín, Departamento de Física, Laboratorio de Materiales Cerámicos y Vítreos, A.A. 568, Medellín (Colombia); Gómez, A. [Universidad Nacional de Colombia, Campus Medellín, Facultad de Minas, Laboratorio de Caracterización de Materiales, A.A. 568, Medellín (Colombia); Bolaños, G. [Low Temperature Laboratory, Department of Physics, University of Cauca, Calle 5 No. 4-70, Popayán (Colombia); Morán, O. [Universidad Nacional de Colombia, Campus Medellín, Departamento de Física, Laboratorio de Materiales Cerámicos y Vítreos, A.A. 568, Medellín (Colombia)

    2015-01-01

    In this work, polycrystalline KNb{sub 1−x}Co{sub x}O{sub 3} (x=0, 0.05 and 0.1) samples were synthesized through standard solid-state reaction, and their structural and magnetic properties were carefully studied. The X-ray powder diffraction (XRD) patterns show reflections of a pure orthorhombic structure (space group Bmm2) with lattice parameters being very close to those reported in the literature. The most important point here is that all the samples ended up being single-phase with no affectation by impurities or segregates. The XRD peaks of Co-doped samples are broadened and shifted to the right side as compared to those of the pristine compound (x=0) suggesting effective substitution of Nb by Co ions. The Co-doped samples exhibit ferromagnetic properties at room temperature, which contrasts starkly with the paramagnetic behavior exhibited by the undoped sample. Interactions between bound magnetic polarons are considered as a possible scenario to explain the appearance of the ferromagnetic signal in the Co-doped samples. - Highlights: • Polycrystalline KNb{sub 1−x}Co{sub x}O{sub 3} (x=0, 0.05 and 0.1) is synthesized by physical route. • XRD patterns show reflections of a pure orthorhombic structure. • No affectation by impurities or segregates is verified by XRD analysis. • The Co-doped samples exhibit ferromagnetic properties at room temperature.

  14. Ultrasonic acoustic levitation for fast frame rate X-ray protein crystallography at room temperature

    Science.gov (United States)

    Tsujino, Soichiro; Tomizaki, Takashi

    2016-05-01

    Increasing the data acquisition rate of X-ray diffraction images for macromolecular crystals at room temperature at synchrotrons has the potential to significantly accelerate both structural analysis of biomolecules and structure-based drug developments. Using lysozyme model crystals, we demonstrated the rapid acquisition of X-ray diffraction datasets by combining a high frame rate pixel array detector with ultrasonic acoustic levitation of protein crystals in liquid droplets. The rapid spinning of the crystal within a levitating droplet ensured an efficient sampling of the reciprocal space. The datasets were processed with a program suite developed for serial femtosecond crystallography (SFX). The structure, which was solved by molecular replacement, was found to be identical to the structure obtained by the conventional oscillation method for up to a 1.8-Å resolution limit. In particular, the absence of protein crystal damage resulting from the acoustic levitation was carefully established. These results represent a key step towards a fully automated sample handling and measurement pipeline, which has promising prospects for a high acquisition rate and high sample efficiency for room temperature X-ray crystallography.

  15. Room-temperature direct bonding of silicon and quartz glass wafers

    Science.gov (United States)

    Wang, Chenxi; Wang, Yuan; Tian, Yanhong; Wang, Chunqing; Suga, Tadatomo

    2017-05-01

    We demonstrate a facile bonding method for combining Si/Si, Si/quartz, and quartz/quartz wafers at room temperature (˜25 °C) using a one-step O2/CF4/H2O plasma treatment. The bonding strengths were significantly improved by adding a small amount of CF4 into the oxygen plasma, such that reliable and tight bonding was obtained after storage in ambient air for 24 h, even without employing heat. Moreover, by introducing water vapor during O2/CF4 plasma treatment, uniform wafer bonding was spontaneously achieved without applying an external force. The fluorinated surface asperities appear to be softened more easily by the interfacial water stress corrosion, enabling reliable bonding at room temperature. Additionally, adding an optimized amount of water vapor to the O2/CF4 plasma increases sufficiently the amount of hydroxyl groups without eliminating the CF4 effect. The additional water adsorbed on the surface may help to close the gap between the bonded wafers, resulting in better bonding efficiency.

  16. Improved Resin–Zirconia Bonding by Room Temperature Hydrofluoric Acid Etching

    Directory of Open Access Journals (Sweden)

    Mun-Hwan Lee

    2015-03-01

    Full Text Available This in vitro study was conducted to evaluate the shear bond strength of “non-self-adhesive” resin to dental zirconia etched with hydrofluoric acid (HF at room temperature and to compare it to that of air-abraded zirconia. Sintered zirconia plates were air-abraded (control or etched with 10%, 20%, or 30% HF for either 5 or 30 min. After cleaning, the surfaces were characterized using various analytical techniques. Three resin cylinders (Duo-Link were bonded to each treated plate. All bonded specimens were stored in water at 37 °C for 24 h, and then half of them were additionally thermocycled 5000 times prior to the shear bond-strength tests (n = 12. The formation of micro- and nano-porosities on the etched surfaces increased with increasing concentration and application time of the HF solution. The surface wettability of zirconia also increased with increasing surface roughness. Higher concentrations and longer application times of the HF solution produced higher bond-strength values. Infiltration of the resin into the micro- and nano-porosities was observed by scanning electron microscopy. This in vitro study suggests that HF slowly etches zirconia ceramic surfaces at room temperature, thereby improving the resin–zirconia bond strength by the formation of retentive sites.

  17. Quantum Correlations of Light from a Room-Temperature Mechanical Oscillator

    Directory of Open Access Journals (Sweden)

    V. Sudhir

    2017-09-01

    Full Text Available When an optical field is reflected from a compliant mirror, its intensity and phase become quantum-correlated due to radiation pressure. These correlations form a valuable resource: the mirror may be viewed as an effective Kerr medium generating squeezed states of light, or the correlations may be used to erase backaction from an interferometric measurement of the mirror’s position. To date, optomechanical quantum correlations have been observed in only a handful of cryogenic experiments, owing to the challenge of distilling them from thermomechanical noise. Accessing them at room temperature, however, would significantly extend their practical impact, with applications ranging from gravitational wave detection to chip-scale accelerometry. Here, we observe broadband quantum correlations developed in an optical field due to its interaction with a room-temperature nanomechanical oscillator, taking advantage of its high-cooperativity near-field coupling to an optical microcavity. The correlations manifest as a reduction in the fluctuations of a rotated quadrature of the field, in a frequency window spanning more than an octave below mechanical resonance. This is due to coherent cancellation of the two sources of quantum noise contaminating the measured quadrature—backaction and imprecision. Supplanting the backaction force with an off-resonant test force, we demonstrate the working principle behind a quantum-enhanced “variational” force measurement.

  18. Unexpected large room-temperature ferromagnetism in porous Cu{sub 2}O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xue [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Sun, Huiyuan, E-mail: huiyuansun@126.com [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Liu, Lihu; Jia, Xiaoxuan; Liu, Huiyuan [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China)

    2015-05-15

    Porous Cu{sub 2}O films have been fabricated on porous anodic alumina substrates using DC-reactive magnetron sputtering with pure Cu targets, and unexpectedly large room temperature ferromagnetism has been observed in the films. The maximum saturation magnetic moment along the out-of-plane direction was as high as 94 emu/cm{sup 3}. Photoluminescence spectra show that the ferromagnetism originates with oxygen vacancies. The ferromagnetism could be adjusted by changing the concentration of oxygen vacancies through annealing in an oxygen atmosphere. These observations suggest that the origin of the ferromagnetism is due to coupling between oxygen vacancies with local magnetic moments in the porous Cu{sub 2}O films, which can occur either directly through exchange interactions between oxygen vacancies, or through the mediation of conduction electrons. Such a ferromagnet without the presence of any ferromagnetic dopant may find applications in spintronic devices. - Highlights: • Porous Cu{sub 2}O films were deposited on porous anodic alumina (PAA) substrates. • Significant room-temperature ferromagnetism has been observed in porous Cu{sub 2}O films. • Ferromagnetism of Cu{sub 2}O films exhibited different magnetic signals with the field. • The saturation magnetization is 94 emu/cm{sup 3} with an out-of-plane.

  19. Indium oxide octahedrons based on sol–gel process enhance room temperature gas sensing performance

    International Nuclear Information System (INIS)

    Mu, Xiaohui; Chen, Changlong; Han, Liuyuan; Shao, Baiqi; Wei, Yuling; Liu, Qinglong; Zhu, Peihua

    2015-01-01

    Highlights: • In 2 O 3 octahedron films are prepared based on sol–gel technique for the first time. • The preparation possesses merits of low temperature, catalyst-free and large production. • It was found that the spin-coating process in film fabrication was key to achieve the octahedrons. • The In 2 O 3 octahedrons could significantly enhance room temperature NO 2 gas sensing performance. - Abstract: Indium oxide octahedrons were prepared on glass substrates through a mild route based on sol–gel technique. The preparation possesses characteristics including low temperature, catalyst-free and large production, which is much distinguished from the chemical-vapor-deposition based methods that usually applied to prepare indium oxide octahedrons. Detailed characterization revealed that the indium oxide octahedrons were single crystalline, with {1 1 1} crystal facets exposed. It was found that the spin-coating technique was key for achieving the indium oxide crystals with octahedron morphology. The probable formation mechanism of the indium oxide octahedrons was proposed based on the experiment results. Room temperature NO 2 gas sensing measurements exhibited that the indium oxide octahedrons could significantly enhance the sensing performance in comparison with the plate-like indium oxide particles that prepared from the dip-coated gel films, which was attributed to the abundant sharp edges and tips as well as the special {1 1 1} crystal facets exposed that the former possessed. Such a simple wet-chemical based method to prepare indium oxide octahedrons with large-scale production is promising to provide the advanced materials that can be applied in wide fields like gas sensing, solar energy conversion, field emission, and so on

  20. Effect of supply air temperature on air distribution in a room with radiant heating and mechanical ventilation

    DEFF Research Database (Denmark)

    Wu, Xiaozhou; Zhao, Jianing; Fang, Lei

    2017-01-01

    The present study focused on the effect of supply air temperature on air distribution in a room with floor heating (FH) or ceiling heating (CH) and mixing ventilation (MV) or displacement ventilation (DV). The vertical distribution of air temperature and velocity in the occupied zone and the hori...... are relevant to the design and control of the hybrid systems with radiant heating systems and mechanical ventilation systems.......The present study focused on the effect of supply air temperature on air distribution in a room with floor heating (FH) or ceiling heating (CH) and mixing ventilation (MV) or displacement ventilation (DV). The vertical distribution of air temperature and velocity in the occupied zone...

  1. Substitution of conventional high-temperature syntheses of inorganic compounds by near-room-temperature syntheses in ionic liquids

    KAUST Repository

    Groh, Matthias Friedrich

    2013-01-01

    The high-temperature syntheses of the low-valent halogenides P2I4, Te2Br, α-Te4I4, Te4(Al2Cl7)2, Te4(Bi6Cl20), Te8(Bi4Cl14),Bi8(AlCl4)2, Bi6Cl7,and Bi6Br7, as well as of WSCl4 andWOCl4 have been replaced by resource-efficient low-temperature syntheses in room temperature ionic liquids (RTILs). The simple one-pot syntheses generally do not require elaborate equipment such as twozone furnaces or evacuated silica ampoules. Compared to the published conventional approaches, reduction of reaction time (up to 80%) and temperature (up to 500 K) and, simultaneously, an increase in yield were achieved. In the majority of cases, the solid products were phase-pure. X-Ray diffraction on single crystals (redetermination of 11 crystal structures) has demonstrated that the quality of the crystals from RTILs is comparable to that of products obtained by chemical transport reactions. © 2013 Verlag der Zeitschrift für Naturforschung, Tübingen.

  2. An experimental study of the effect of different starting room temperatures on occupant comfort in Danish summer weather

    DEFF Research Database (Denmark)

    Bourdakis, Eleftherios; Simone, Angela; Olesen, Bjarne W.

    2018-01-01

    As office workers will usually have a slightly elevated metabolic rate when arriving at work, they may prefer a room temperature below the comfort range for sedentary activity in the morning. This possibility was studied in an experiment with 25 young people, male and female, exposed to four...... different conditions. Each condition consisted of two sessions, the simulated commute (activity equivalent to walking to work) and the office session. Each office session had a different starting room temperature, namely 18.5 °C, 20 °C, 21.5 °C or 23 °C, followed by an increasing temperature “ramp” of 1.5K...... every 30 min. During the last 30 min the temperature remained constant. Physical measurements were continuously recorded and subjective evaluation questionnaires were completed every 30 min. It was observed that, upon arrival at the office-lab, a room temperature of 20 °C provided a thermal environment...

  3. Contribution of structural order-disorder to the room-temperature photoluminescence of lead zirconate titanate powders

    International Nuclear Information System (INIS)

    Anicete-Santos, Marcos; Silva, Margarete S.; Orhan, Emmanuelle; Goes, Marcio S.; Zaghete, Maria A.; Paiva-Santos, Carlos O.; Pizani, Paulo S.; Cilense, Mario; Varela, Jose A.; Longo, Elson

    2007-01-01

    Intense and broad visible photoluminescent (PL) band was observed at room temperature in structurally disordered PbZr 0.53 Ti 0.47 O 3 powders. The lead zirconate titanate PbZr 0.53 Ti 0.47 O 3 powders prepared by the polymeric precursor method and heat treated at different temperatures were structurally characterized at long range by means of X-ray diffraction. The PL was measured at room temperature samples heat treated at different temperatures. Experimental measurements and quantum-mechanical calculations showed that the high structural order and the high structural disorder in PbZr 0.53 Ti 0.47 O 3 lattice are not favorable to the intense PL emission. Only samples containing simultaneous structural order and disorder in their lattice present the intense visible PL emission at room temperature

  4. Post Deformation at Room and Cryogenic Temperature Cooling Media on Severely Deformed 1050-Aluminum

    Science.gov (United States)

    Khorrami, M. Sarkari; Kazeminezhad, M.

    2018-02-01

    The annealed 1050-aluminum sheets were initially subjected to the severe plastic deformation through two passes of constrained groove pressing (CGP) process. The obtained specimens were post-deformed by friction stir processing at room and cryogenic temperature cooling media. The microstructure evolutions during mentioned processes in terms of grain structure, misorientation distribution, and grain orientation spread (GOS) were characterized using electron backscattered diffraction. The annealed sample contained a large number of "recrystallized" grains and relatively large fraction (78%) of high-angle grain boundaries (HAGBs). When CGP process was applied on the annealed specimen, the elongated grains with interior substructure were developed, which was responsible for the formation of 80% low-angle grain boundaries. The GOS map of the severely deformed specimen manifested the formation of 43% "distorted" and 51% "substructured" grains. The post deformation of severely deformed aluminum at room temperature led to the increase in the fraction of HAGBs from 20 to 60%. Also, it gave rise to the formation of "recrystallized" grains with the average size of 13 μm, which were coarser than the grains predicted by Zener-Hollomon parameter. This was attributed to the occurrence of appreciable grain growth during post deformation. In the case of post deformation at cryogenic temperature cooling medium, the grain size was decreased, which was in well agreement with the predicted grain size. The cumulative distribution of misorientation was the same for both processing routes. Mechanical properties characterizations in terms of nano-indentation and tensile tests revealed that the post deformation process led to the reduction in hardness, yield stress, and ultimate tensile strength of the severely deformed aluminum.

  5. Fatigue Life Prediction of 2D Woven Ceramic-Matrix Composites at Room and Elevated Temperatures

    Science.gov (United States)

    Longbiao, Li

    2017-03-01

    In this paper, the fatigue life of 2D woven ceramic-matrix composites, i.e., SiC/SiC, SiC/Si-N-C, SiC/Si-B4C, and Nextel 610™/Aluminosilicate, at room and elevated temperatures has been predicted using the micromechanics approach. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. The Budiansky-Hutchinson-Evans shear-lag model was used to describe the microstress field of the damaged composite considering fibers failure. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress and fibers strength degradation model and oxidation region propagation model have been adopted to analyze the fatigue and oxidation effects on fatigue life of the composite, which is controlled by interface frictional slip and diffusion of oxygen gas through matrix multicrackings. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface/fiber oxidation model, interface wear model and fibers statistical failure model at elevated temperatures, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfy the Global Load Sharing (GLS) criterion. When the broken fibers fraction approaches to the critical value, the composites fatigue fractures. The fatigue life S- N curves of 2D SiC/SiC, SiC/Si-N-C, SiC/Si-B4C, and Nextel 610™/Aluminosilicate composites at room temperature and 800, 1000 and 1200 °C in air and steam have been predicted.

  6. Room temperature negative differential resistance in terahertz quantum cascade laser structures

    Energy Technology Data Exchange (ETDEWEB)

    Albo, Asaf, E-mail: asafalbo@gmail.com; Hu, Qing [Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Reno, John L. [Center for Integrated Nanotechnologies, Sandia National Laboratories, MS 1303, Albuquerque, New Mexico 87185-1303 (United States)

    2016-08-22

    The mechanisms that limit the temperature performance of GaAs/Al{sub 0.15}GaAs-based terahertz quantum cascade lasers (THz-QCLs) have been identified as thermally activated LO-phonon scattering and leakage of charge carriers into the continuum. Consequently, the combination of highly diagonal optical transition and higher barriers should significantly reduce the adverse effects of both mechanisms and lead to improved temperature performance. Here, we study the temperature performance of highly diagonal THz-QCLs with high barriers. Our analysis uncovers an additional leakage channel which is the thermal excitation of carriers into bounded higher energy levels, rather than the escape into the continuum. Based on this understanding, we have designed a structure with an increased intersubband spacing between the upper lasing level and excited states in a highly diagonal THz-QCL, which exhibits negative differential resistance even at room temperature. This result is a strong evidence for the effective suppression of the aforementioned leakage channel.

  7. Strain rate effects in nuclear steels at room and higher temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Solomos, G. E-mail: george.solomos@jrc.it; Albertini, C.; Labibes, K.; Pizzinato, V.; Viaccoz, B

    2004-04-01

    An investigation of strain rate, temperature and size effects in three nuclear steels has been conducted. The materials are: ferritic steel 20MnMoNi55 (vessel head), austenitic steel X6CrNiNb1810 (upper internal structure), and ferritic steel 26NiCrMo146 (bolting). Smooth cylindrical tensile specimens of three sizes have been tested at strain rates from 0.001 to 300 s{sup -1}, at room and elevated temperatures (400-600 deg. C). Full stress-strain diagrams have been obtained, and additional parameters have been calculated based on them. The results demonstrate a clear influence of temperature, which amounts into reducing substantially mechanical strengths with respect to RT conditions. The effect of strain rate is also shown. It is observed that at RT the strain rate effect causes up shifting of the flow stress curves, whereas at the higher temperatures a mild downshifting of the flow curves is manifested. Size effect tendencies have also been observed. Some implications when assessing the pressure vessel structural integrity under severe accident conditions are considered.

  8. Highly efficient organic solar Cells based on a robust room-temperature solution-processed copper iodide hole transporter

    KAUST Repository

    Zhao, Kui

    2015-07-30

    Achieving high performance and reliable organic solar cells hinges on the development of stable and energetically suitable hole transporting buffer layers in tune with the electrode and photoactive materials of the solar cell stack. Here we have identified solution-processed copper(I) iodide (CuI) thin films with low-temperature processing conditions as an effective hole–transporting layer (HTL) for a wide range of polymer:fullerene bulk heterojunction (BHJ) systems. The solar cells using CuI HTL show higher power conversion efficiency (PCE) in standard device structure for polymer blends, up to PCE of 8.8%, as compared with poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, for a broad range of polymer:fullerene systems. The CuI layer properties and solar cell device behavior are shown to be remarkably robust and insensitive to a wide range of processing conditions of the HTL, including processing solvent, annealing temperature (room temperature up to 200 °C), and film thickness. CuI is also shown to improve the overall lifetime of solar cells in the standard architecture as compared to PEDOT:PSS. We further demonstrate promising solar cell performance when using CuI as top HTL in an inverted device architecture. The observation of uncommon properties, such as photoconductivity of CuI and templating effects on the BHJ layer formation, are also discussed. This study points to CuI as being a good candidate to replace PEDOT:PSS in solution-processed solar cells thanks to the facile implementation and demonstrated robustness of CuI thin films.

  9. Evolution of interphase and intergranular strain in zirconium-niobium alloys during deformation at room temperature

    Science.gov (United States)

    Cai, Song

    Zr-2.5Nb is currently used for pressure tubes in the CANDU (CANada Deuterium Uranium) reactor. A complete understanding of the deformation mechanism of Zr-2.5Nb is important if we are to accurately predict the in-reactor performance of pressure tubes and guarantee normal operation of the reactors. This thesis is a first step in gaining such an understanding; the deformation mechanism of ZrNb alloys at room temperature has been evaluated through studying the effect of texture and microstructure on deformation. In-situ neutron diffraction was used to monitor the evolution of the lattice strain of individual grain families along both the loading and Poisson's directions and to track the development of interphase and intergranular strains during deformation. The following experiments were carried out with data interpreted using elasto-plastic modeling techniques: (1) Compression tests of a 100%betaZr material at room temperature. (2) Tension and compression tests of hot rolled Zr-2.5Nb plate material. (3) Compression of annealed Zr-2.5Nb. (4) Cyclic loading of the hot rolled Zr-2.5Nb. (5) Compression tests of ZrNb alloys with different Nb and oxygen contents. The experimental results were interpreted using a combination of finite element (FE) and elasto-plastic self-consistent (EPSC) models. The phase properties and phase interactions well represented by the FE model, the EPSC model successfully captured the evolution of intergranular constraint during deformation and provided reasonable estimates of the critical resolved shear stress and hardening parameters of different slip systems under different conditions. The consistency of the material parameters obtained by the EPSC model allows the deformation mechanism at room temperature and the effect of textures and microstructures of ZrNb alloys to be understood. This work provides useful information towards manufacturing of Zr-2.5Nb components and helps in producing ideal microstructures and material properties for

  10. p-PEDOT:PSS as a heterojunction partner with n-ZnO for detection of LPG at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ladhe, R.D. [Thin Film and Nano Science Laboratory, Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001 (M.S.) (India); Gurav, K.V. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Pawar, S.M. [Solar Cell Laboratory, LG Components R and D Center, 1271, Sa-Dong, Sanggrok-gu, Ansan-si, Gyeonggi-do 426-791 (Korea, Republic of); Kim, J.H. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Sankapal, B.R., E-mail: brsankapal@rediffmail.com [Thin Film and Nano Science Laboratory, Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001 (M.S.) (India)

    2012-02-25

    Highlights: Black-Right-Pointing-Pointer Formation of heterojunction n-ZnO and p-PEDOT:PSS at room temperature (27 Degree-Sign C). Black-Right-Pointing-Pointer Use of this heterojunction as room temperature LPG sensor. Black-Right-Pointing-Pointer Remarkable gas response with good stability of the sensing device. Black-Right-Pointing-Pointer Use of heterojunction could offer cost-effective LPG sensor that is ecological-friendly. Black-Right-Pointing-Pointer The mass production using scalable room temperature chemical deposition process. - Abstract: Investigation towards the performance of room temperature (27 Degree-Sign C) liquefied petroleum gas (LPG) sensor based on the heterojunction between p-PEDOT:PSS and n-type ZnO is reported. The junction was developed by using chemically deposited ZnO film on to fluorine doped tin oxide (FTO) coated glass substrate followed by coating of thin slurry layer of PEDOT:PSS by using spin coating technique. Both these methods are simple, inexpensive and suitable for large area applications. Different characterization techniques were used to characterize structural, surface morphological and compositional of the material deposited. LPG sensing behavior of the heterojunction was studied at room temperature along with the stability studies. At room temperature, the heterojunction showed 58.8% sensitivity upon exposure to 1000 ppm of LPG with good response and recovery time like 225 s and 190 s, respectively. Furthermore, the LPG sensor reported is cost-effective, user friendly, and easy to fabricate using low cost chemical methods at room temperature.

  11. Towards a Kieselguhr- and PVPP-Free Clarification and Stabilization Process of Rough Beer at Room-Temperature Conditions.

    Science.gov (United States)

    Cimini, Alessio; Moresi, Mauro

    2018-01-01

    In this work, the main constraint (that is, beer chilling and chill haze removing) of the current beer conditioning techniques using Kieselguhr filtration and Polyvinylpolypyrrolidone (PVPP) treatment was overcome by developing a novel higher-throughput conditioning process, operating at room temperatures with no use of filter aids. The effect of filtration temperature (T F ) in the range of 0 to 40 °C on the hydraulic permeability of ceramic hollow-fiber (HF) membranes with nominal pore size of 0.2 to 1.4 μm, as well as on their limiting permeation flux (J * ) when feeding precentrifuged rough beer, was preliminarily assessed. When using the 1.4-μm HF membrane operating at T F ≥ 20 °C, it was possible to enhance the average permeation flux at values (676 to 1844 L/m 2 /h), noticeably higher than those (250 to 500 L/m 2 /h) characteristics of conventional powder filtration. Despite its acceptable permanent haze, the resulting beer permeate still exhibited colloidal instability. By resorting to the commercial enzyme preparation Brewers Clarex® before beer clarification, it was possible to significantly improve its colloidal stability as measured using a number of European Brewing Convention forcing tests, especially with respect to that of precentrifuged rough beer by itself. By combining the above enzymatic treatment with membrane clarification at 30 °C across the ceramic 1.4-μm HF membrane module, it was possible to limit the haze development due to chilling, sensitive proteins, and alcohol addition to as low as 0.78, 4.1, and 4.0 EBC-U, respectively, the enzymatic treatment being by far more effective than that using PVPP. A novel Kieselguhr- and PVPP-free rough beer conditioning process at room temperatures was set up. By submitting precentrifuged rough beer to commercial preparation Brewers Clarex ® and then to membrane clarification at 30 °C across a ceramic 1.4-μm hollow-fiber membrane module, it was possible to obtain a clear and stable beer with

  12. Viscoelasticity and texture of spreadable cheeses with different fat contents at refrigeration and room temperatures.

    Science.gov (United States)

    Bayarri, S; Carbonell, I; Costell, E

    2012-12-01

    The effect of the 2 common consumption temperatures, refrigeration temperature (10°C) and room temperature (22°C), on the viscoelasticity, mechanical properties, and perceived texture of commercial cream cheeses was studied. Two samples with different fat contents, regular and low fat, from each of 4 selected commercial brands were analyzed. The selection criteria were based on identification of brands with different percentages of fat content reduction between the regular- and low-fat samples (35, 50, 84, and 98.5%). The fat content of regular-fat samples ranged from 19.8 to 26.0% (wt/wt), and that of low-fat samples ranged from 0.3 to 13.0% (wt/wt). Viscoelasticity was measured in a controlled-stress rheometer using parallel-plate geometry, and the mechanical characteristics of samples were measured using the spreadability test. Differences in the intensity of thickness, creaminess, and roughness between the regular- and low-fat samples of each commercial brand were evaluated at each of the selected temperatures by using the paired comparisons test. At 10°C, all samples showed higher viscoelastic modulus values, firmness, and stickiness, and lower spreadability than when they were measured at 22°C. Differences in viscoelasticity and mechanical properties between each pair of samples of the same brand were greater at 10°C than at 22°C because of the influence not only of fat content but also of fat state. Ingestion temperature did not modify the sensory differences detected between each pair of samples in terms of creaminess and roughness, but it did modify the differences detected in thickness. The joint consideration of sample composition, fat state, and product behavior during oral processing could explain the differences detected in thickness perceived because of measurement temperatures. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  13. Wide bandgap BaSnO3 films with room temperature conductivity exceeding 104 S cm−1

    Science.gov (United States)

    Prakash, Abhinav; Xu, Peng; Faghaninia, Alireza; Shukla, Sudhanshu; Ager, Joel W.; Lo, Cynthia S.; Jalan, Bharat

    2017-01-01

    Wide bandgap perovskite oxides with high room temperature conductivities and structural compatibility with a diverse family of organic/inorganic perovskite materials are of significant interest as transparent conductors and as active components in power electronics. Such materials must also possess high room temperature mobility to minimize power consumption and to enable high-frequency applications. Here, we report n-type BaSnO3 films grown using hybrid molecular beam epitaxy with room temperature conductivity exceeding 104 S cm−1. Significantly, these films show room temperature mobilities up to 120 cm2 V−1 s−1 even at carrier concentrations above 3 × 1020 cm−3 together with a wide bandgap (3 eV). We examine the mobility-limiting scattering mechanisms by calculating temperature-dependent mobility, and Seebeck coefficient using the Boltzmann transport framework and ab-initio calculations. These results place perovskite oxide semiconductors for the first time on par with the highly successful III–N system, thereby bringing all-transparent, high-power oxide electronics operating at room temperature a step closer to reality. PMID:28474675

  14. Wide bandgap BaSnO3 films with room temperature conductivity exceeding 104 S cm-1

    Science.gov (United States)

    Prakash, Abhinav; Xu, Peng; Faghaninia, Alireza; Shukla, Sudhanshu; Ager, Joel W.; Lo, Cynthia S.; Jalan, Bharat

    2017-05-01

    Wide bandgap perovskite oxides with high room temperature conductivities and structural compatibility with a diverse family of organic/inorganic perovskite materials are of significant interest as transparent conductors and as active components in power electronics. Such materials must also possess high room temperature mobility to minimize power consumption and to enable high-frequency applications. Here, we report n-type BaSnO3 films grown using hybrid molecular beam epitaxy with room temperature conductivity exceeding 104 S cm-1. Significantly, these films show room temperature mobilities up to 120 cm2 V-1 s-1 even at carrier concentrations above 3 × 1020 cm-3 together with a wide bandgap (3 eV). We examine the mobility-limiting scattering mechanisms by calculating temperature-dependent mobility, and Seebeck coefficient using the Boltzmann transport framework and ab-initio calculations. These results place perovskite oxide semiconductors for the first time on par with the highly successful III-N system, thereby bringing all-transparent, high-power oxide electronics operating at room temperature a step closer to reality.

  15. Enhancing transglutaminase production ofStreptomyces mobaraensisby iterative mutagenesis breeding with atmospheric and room-temperature plasma (ARTP).

    Science.gov (United States)

    Jiang, Ying; Shang, Yue-Peng; Li, Hao; Zhang, Chao; Pan, Jiang; Bai, Yun-Peng; Li, Chun-Xiu; Xu, Jian-He

    2017-01-01

    To improve the fermentation production of transglutaminase (TGase) from Streptomyces mobaraensis for applications in the food industry, the atmospheric and room-temperature plasma (ARTP) mutagenesis was applied to breed S. mobaraensis mutants with increased TGase production. After eight rounds of iterative ARTP mutagenesis, four genetically stable mutants, Sm 5-V1, Sm 6-V13, Sm 2-V10, and Sm 7-V12, were identified, which showed increased TGase production by 27, 24, 24, and 19%, respectively. The best mutant Sm 5-V1 exhibited a maximum TGase activity of 5.85 U/mL during flask fermentation. Compared to the wild-type strain, the transcription levels of the zymogen TGase genes in the mutants increased significantly as indicated by quantitative real-time PCR, while the gene nucleotide sequences of the mutants did not change at all. It was shown that the overexpression of TGase zymogen gene in the mutants contributes to the increase in TGase production. ARTP is a potentially efficient tool for microbial mutation breeding to bring some significant changes required for the industrial applications.

  16. Defect stabilization and reverse annealing in ZnO implanted with nitrogen at room and cryogenic temperature

    Science.gov (United States)

    Azarov, Alexander; Wendler, Elke; Monakhov, Edouard; Svensson, Bengt G.

    2018-03-01

    Despite the fact that nitrogen is a potential acceptor dopant and one of the most studied elements in ZnO, lacking understanding of associated defects and their thermal evolution limits realization of reliable p-type doping of ZnO. Here, we use ion implantation to introduce N at room temperature (RT) and 15 K in ZnO samples with/without a pre-existing buried disorder layer formed by Ag ion bombardment aligned along the [0001] direction. The buried layer contains a high concentration of extended defects, which act as traps for migrating point defects. Channeling analysis shows that reverse annealing occurs in all the N implanted samples during post-implant heat treatment above 600 °C with strong non-linear additive damage accumulation in the co-implanted samples. The reverse annealing effect is less stable in the RT co-implanted sample and the data suggest that a high local concentration of intrinsic point defects, like Zn interstitials, promotes the stability of the N-defect clusters responsible for the reverse annealing. This suggestion is also corroborated by enhanced and defect-mediated Ag outdiffusion at 1100 °C in the RT co-implanted samples.

  17. Breeding L-arginine-producing strains by a novel mutagenesis method: Atmospheric and room temperature plasma (ARTP).

    Science.gov (United States)

    Cheng, Gong; Xu, Jianzhong; Xia, Xiuhua; Guo, Yanfeng; Xu, Kai; Su, Cunsheng; Zhang, Weiguo

    2016-07-03

    A plasma jet, driven by an active helium atom supplied with an atmospheric and room temperature plasma (ARTP) biological breeding system, was used as a novel method to breed L-arginine high-yielding strains. A mutant with resistance to L-homoarginine and 8-azaguaine, ARG 3-15 (L-HA(r), 8-AG(r), L-His(-)), was screened after several rounds of screening. The L-arginine production of these mutants was more than that of the original strain, increased by 43.79% for ARG 3-15. Moreover, N-acetyl-L-glutamate synthase activity of these mutants was also increased. After a series of passages, the hereditary properties of these mutants were found to be stable. Interestingly, beet molasses was utilized in a co-feeding fermentation and benefited to increase the productivity by 5.88%. Moreover, the fermentation with 1.0 g/L betaine could produce 9.33% more L-arginine than without betaine. In fed-batch fermentation, C. glutamicum ARG 3-15 began to produce L-arginine at the initial of logarithmic phase, and continuously increased over 24 hr to a final titer of 45.36 ± 0.42 g/L. The L-arginine productivity was 0.571 g/L/hr and the conversion of glucose (α) was 32.4% after 96 hr. These results indicated that C. glutamicum ARG 3-15 is a promising industrial producer.

  18. Cumulative damage fatigue tests on nuclear reactor Zircaloy-2 fuel tubes at room temperature and 3000C

    International Nuclear Information System (INIS)

    Pandarinathan, P.R.; Vasudevan, P.

    1980-01-01

    Cumulative damage fatigue tests were conducted on the Zircaloy-2 fuel tubes at room temperature and 300 0 C on the modified Moore type, four-point-loaded, deflection-controlled, rotating bending fatigue testing machine. The cumulative cycle ratio at fracture for the Zircaloy-2 fuel tubes was found to depend on the sequence of loading, stress history, number of cycles of application of the pre-stress and the test temperature. A Hi-Lo type fatigue loading was found to be very much damaging at room temperature and this feature was not observed in the tests at 300 0 C. Results indicate significant differences in damage interaction and damage propagation under cumulative damage tests at room temperature and at 300 0 C. Block-loading fatigue tests are suggested as the best method to determine the life-time of Zircaloy-2 fuel tubes under random fatigue loading during their service in the reactor. (orig.)

  19. Demand control on room level of the supply air temperature in an air heating and ventilation system

    DEFF Research Database (Denmark)

    Polak, Joanna; Afshari, Alireza; Bergsøe, Niels Christian

    2017-01-01

    The aim of this study was to investigate a new strategy for control of supply air temperature in an integrated air heating and ventilation system. The new strategy enables demand control of supply air temperature in individual rooms. The study is based on detailed dynamic simulations of a combined...

  20. Miniaturized Planar Room Temperature Ionic Liquid Electrochemical Gas Sensor for Rapid Multiple Gas Pollutants Monitoring.

    Science.gov (United States)

    Wan, Hao; Yin, Heyu; Lin, Lu; Zeng, Xiangqun; Mason, Andrew J

    2018-02-01

    The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.

  1. Magnetic refrigeration at room temperature - from magnetocaloric materials to a prototype

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Pryds, Nini; Bahl, Christian Robert Haffenden

    2011-01-01

    materials, their shaping and graded composition for technological use. Modelling the performance of a permanent magnet with optimum use of the flux and relatively low weight, and designing and constructing a prototype continuous magnetic refrigeration device have also been major tasks in the project......Based on the magnetocaloric effect, magnetic refrigeration at room temperature has for the past decade been a promising, environmentally friendly new energy technology predicted to have a significantly higher efficiency than the present conventional methods. However, so far only a few prototype...... refrigeration machines have been presented worldwide and there are still many scientific and technological challenges to be overcome. We report here on the MagCool project, which spans all the way from basic materials studies to the construction of a prototype. Emphasis has been on ceramic magnetocaloric...

  2. From molten salts to room temperature ionic liquids: simulation studies on chloroaluminate systems.

    Science.gov (United States)

    Salanne, Mathieu; Siqueira, Leonardo J A; Seitsonen, Ari P; Madden, Paul A; Kirchner, Barbara

    2012-01-01

    An interaction potential including chloride anion polarization effects, constructed from first-principles calculations, is used to examine the structure and transport properties of a series of chloroaluminate melts. A particular emphasis was given to the study of the equimolar mixture of aluminium chloride with 1-ethyl-3-methylimidazolium chloride, which forms a room temperature ionic liquid EMI+ -AlCl4-. The structure yielded by the classical simulations performed within the framework of the polarizable ion model is compared to the results obtained from entirely electronic structure-based simulations: An excellent agreement between the two flavors of molecular dynamics is observed. When changing the organic cation EMI+ by an inorganic cation with a smaller ionic radius (Li+, Na+, K+), the chloroaluminate speciation becomes more complex, with the formation of Al2Cl7-, in small amounts. The calculated transport properties (diffusion coefficients, electrical conductivity and viscosity) of EMI+ -AlCl4- are in good agreement with experimental data.

  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

    to the one described in [4] (cf. Fig 1a): The displacement of the high Q membrane is capacitively coupled to a plate capacitor that is connected in parallel to a ferrite inductor. A change in capacitance alters the LC resonance frequency, thereby creating coupling between the membrane and the LC circuit...... 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...... to optical excitations in a high finesse cavity.In this work, we have experimentally realized both optical and electrical detection of coupling in a roomtemperature electromechanical system composed of an LC circuit and a 100-nm thick SiN nanomembrane coated by 50 nm Aluminum. We follow an approach similar...

  4. Room temperature synthesis of a Zn(II) metal-organic coordination polymer for dye removal

    Science.gov (United States)

    Abbasi, Alireza; Gharib, Maniya; Najafi, Mahnaz; Janczak, Jan

    2016-03-01

    A new one-dimensional (1D) coordination polymer, [Zn(4,4‧-bpy)(H2O)4](ADC)·4H2O (1) (4,4‧-bpy=4,4‧-bipyridine and H2ADC=acetylenedicarboxylic acid), was synthesized at room temperature. The crystal structure of the coordination polymer was determined by single-crystal X-ray diffraction analysis. Compound 1 was also characterized by FT-IR, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). The catalytic activity of 1 was evaluated in the color removal of Bismarck brown as a representative of dye pollutant in water under mild conditions. Coordination polymer 1 exhibited good catalytic activity and stability in the decolorization of Bismarck brown and could be easily recovered and reused for at least three cycles.

  5. Room-temperature deposition of diamond-like carbon field emitter on flexible substrates

    International Nuclear Information System (INIS)

    Chen, H.; Iliev, M.N.; Liu, J.R.; Ma, K.B.; Chu, W.-K.; Badi, N.; Bensaoula, A.; Svedberg, E.B.

    2006-01-01

    Room-temperature fabrication of diamond-like carbon electron field emitters on flexible polyimide substrate is reported. These thin film field emitters are made using an Ar gas cluster ion beam assisted C 6 vapor deposition method. The bond structure of the as-deposited diamond-like carbon film was studied using Raman spectroscopy. The field emission characteristics of the deposited films were also measured. Electron current densities over 15 mA/cm 2 have been recorded under an electrical field of about 65 V/μm. These diamond-like carbon field emitters are easy and inexpensive to fabricate. The results are promising for flexible field-emission fabrication without the need of complex patterning and tip shaping as compared to the Spindt-type field emitters

  6. Ceramic stabilization of hazardous wastes: a high performance room temperature process

    International Nuclear Information System (INIS)

    Maloney, M.D.

    1996-01-01

    ANL has developed a room-temperature process for converting hazardous materials to a ceramic structure. It is similar to vitrification but is achieved at low cost, similar to conventional cement stabilization. The waste constituents are both chemically stabilized and physically encapsulated, producing very low leaching levels and the potential for delisting. The process, which is pH-insensitive, is ideal for inorganic sludges and liquids, as well as mixed chemical-radioactive wastes, but can also handle significant percentages of salts and even halogenated organics. High waste loadings are possible and densification occurs,so that volumes are only slightly increased and in some cases (eg, incinerator ash) are reduced. The ceramic product has strength and weathering properties far superior to cement products

  7. Room-temperature effects of UV radiation in KBr:Eu{sup 2+} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Salas, R.; Melendrez, R. [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada - IFUNAM, Ensenada, Apartado Postal 2732 Ensenada, BC, 22800 (Mexico); Aceves, R.; Rodriguez, R.; Barboza-Flores, M. [Centro de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088 Hermosillo, Sonora, 83190 (Mexico)

    1996-07-01

    Thermoluminescence and optical absorption measurements have been carried out in KBr:Eu{sup 2+} crystals irradiated with monochromatic UV light (200-300 nm) and x-rays at room temperature. For UV- and x-irradiated crystals strong similarities between the thermoluminescence glow curves have been found, suggesting that the low-energy UV radiation produces the same defects as produced by x-irradiation in this material. The thermoluminescence glow curves are composed of six glow peaks located at 337, 383, 403, 435, 475 and 509 K. Thermal annealing experiments in previously irradiated crystals show clearly a correlation between the glow peak located at 383 K and the F-centre thermal bleaching process. Also, the excitation spectrum for each thermoluminescence glow peak has been investigated, showing that the low-energy radiation induces the formation of F centres. (author)

  8. Gallium-Based Room-Temperature Liquid Metals: Actuation and Manipulation of Droplets and Flows

    Directory of Open Access Journals (Sweden)

    Leily Majidi

    2017-08-01

    Full Text Available Gallium-based room-temperature liquid metals possess extremely valuable properties, such as low toxicity, low vapor pressure, and high thermal and electrical conductivity enabling them to become suitable substitutes for mercury and beyond in wide range of applications. When exposed to air, a native oxide layer forms on the surface of gallium-based liquid metals which mechanically stabilizes the liquid. By removing or reconstructing the oxide skin, shape and state of liquid metal droplets and flows can be manipulated/actuated desirably. This can occur manually or in the presence/absence of a magnetic/electric field. These methods lead to numerous useful applications such as soft electronics, reconfigurable devices, and soft robots. In this mini-review, we summarize the most recent progresses achieved on liquid metal droplet generation and actuation of gallium-based liquid metals with/without an external force.

  9. Concept of polymer alloy electrolytes: towards room temperature operation of lithium-polymer batteries

    International Nuclear Information System (INIS)

    Noda, Kazuhiro; Yasuda, Toshikazu; Nishi, Yoshio

    2004-01-01

    Polymer alloy technique is very powerful tool to tune the ionic conductivity and mechanical strength of polymer electrolyte. A semi-interpenetrating polymer network (semi-IPN) polymer alloy electrolyte, composed of non-cross-linkable siloxane-based polymer and cross-linked 3D network polymer, was prepared. Such polymer alloy electrolyte has quite high ionic conductivity (more than 10 -4 Scm -1 at 25 o C and 10 -5 Scm -1 at -10 o C) and mechanical strength as a separator film with a wide electrochemical stability window. A lithium metal/semi-IPN polymer alloy solid state electrolyte/LiCoO 2 cell demonstrated promising cycle performance with room temperature operation of the energy density of 300Wh/L and better rate performance than conventional PEO based lithium polymer battery ever reported

  10. Surface tension anomalies in room temperature ionic liquids-acetone solutions

    Science.gov (United States)

    Abe, Hiroshi; Murata, Keisuke; Kiyokawa, Shota; Yoshimura, Yukihiro

    2018-05-01

    Surface tension anomalies were observed in room temperature ionic liquid (RTIL)-acetone solutions. The RTILs are 1-alkyl-3-methylimidazorium iodide with [Cnmim][I] in a [Cnmim][I]-x mol% acetone. The maximum value of the surface tension appeared at 40 mol% acetone, although density decreased monotonically with an increase in acetone concentration. A small alkyl chain length effect of the Cnmim+ cations was observed in the surface tension. By the Gibbs adsorption isotherm, it was found that I- anion-mediated surface structure became dominant above 40 mol%. In the different [Cnmim][TFSI]-acetone mixtures, normal decay of the surface tension was observed on the acetone concentration scale, where TFSI- is bis(trifluoromethanesulfonyl)imide.

  11. Strengthening mechanisms of indirect-extruded Mg–Sn based alloys at room temperature

    Directory of Open Access Journals (Sweden)

    Wei Li Cheng

    2014-12-01

    Full Text Available The strength of a material is dependent on how dislocations in its crystal lattice can be easily propagated. These dislocations create stress fields within the material depending on their intrinsic character. Generally, the following strengthening mechanisms are relevant in wrought magnesium materials tested at room temperature: fine-grain strengthening, precipitate strengthening and solid solution strengthening as well as texture strengthening. The indirect-extruded Mg–8Sn (T8 and Mg–8Sn–1Al–1Zn (TAZ811 alloys present superior tensile properties compared to the commercial AZ31 alloy extruded in the same condition. The contributions to the strengthen of Mg–Sn based alloys made by four strengthening mechanisms were calculated quantitatively based on the microstructure characteristics, physical characteristics, thermomechanical analysis and interactions of alloying elements using AZ31 alloy as benchmark.

  12. Tunable room-temperature magnetic skyrmions in Ir/Fe/Co/Pt multilayers

    Science.gov (United States)

    Soumyanarayanan, Anjan; Raju, M.; Gonzalez Oyarce, A. L.; Tan, Anthony K. C.; Im, Mi-Young; Petrović, A. P.; Ho, Pin; Khoo, K. H.; Tran, M.; Gan, C. K.; Ernult, F.; Panagopoulos, C.

    2017-09-01

    Magnetic skyrmions are nanoscale topological spin structures offering great promise for next-generation information storage technologies. The recent discovery of sub-100-nm room-temperature (RT) skyrmions in several multilayer films has triggered vigorous efforts to modulate their physical properties for their use in devices. Here we present a tunable RT skyrmion platform based on multilayer stacks of Ir/Fe/Co/Pt, which we study using X-ray microscopy, magnetic force microscopy and Hall transport techniques. By varying the ferromagnetic layer composition, we can tailor the magnetic interactions governing skyrmion properties, thereby tuning their thermodynamic stability parameter by an order of magnitude. The skyrmions exhibit a smooth crossover between isolated (metastable) and disordered lattice configurations across samples, while their size and density can be tuned by factors of two and ten, respectively. We thus establish a platform for investigating functional sub-50-nm RT skyrmions, pointing towards the development of skyrmion-based memory devices.

  13. Room temperature deformation mechanisms in ultrafine-grained materials processed by hot isostatic pressing

    International Nuclear Information System (INIS)

    Cao, W.Q.; Dirras, G.F.; Benyoucef, M.; Bacroix, B.

    2007-01-01

    Ultrafine-grained (uf-g) and microcrystalline-grained (mc-g) irons have been fabricated by hot isostatic pressing of nanopowders. The mechanical properties have been characterized by compressive tests at room temperature and the resulting microstructures and textures have been determined by combining electron back scatter diffraction and transmission electron microscopy. A transition of the deformation mode, from work hardening to work softening occurs for grain sizes below ∼1 μm, reflecting a transition of the deformation mode from homogeneous to localized deformation into shear bands (SBs). The homogeneous deformation is found to be lattice dislocation-based while the deformation within SBs involves lattice dislocations as well as boundary-related mechanisms, possibly grain boundary sliding accommodated by boundary opening

  14. Direct Observation of Room-Temperature Polar Ordering in Colloidal GeTe Nanocrystals

    International Nuclear Information System (INIS)

    Polking, Mark J.; Zheng, Haimei; Urban, Jeffrey J.; Milliron, Delia J.; Chan, Emory; Caldwell, Marissa A.; Raoux, Simone; Kisielowski, Christian F.; Ager, Joel W. III; Ramesh, Ramamoorthy; Alivisatos, A.P.

    2009-01-01

    Ferroelectrics and other materials that exhibit spontaneous polar ordering have demonstrated immense promise for applications ranging from non-volatile memories to microelectromechanical systems. However, experimental evidence of polar ordering and effective synthetic strategies for accessing these materials are lacking for low-dimensional nanomaterials. Here, we demonstrate the synthesis of size-controlled nanocrystals of the polar material germanium telluride (GeTe) using colloidal chemistry and provide the first direct evidence of room-temperature polar ordering in nanocrystals less than 5 nm in size using aberration-corrected transmission electron microscopy. Synchrotron x-ray diffraction and Raman studies demonstrate a sizeable polar distortion and a reversible size-dependent polar phase transition in these nanocrystals. The stability of polar ordering in solution-processible nanomaterials suggests an economical avenue to Tbit/in2-density non-volatile memory devices and other applications.

  15. Magnetic Measurements of the LHC Quadrupole and Dipole Magnets at Room Temperature

    CERN Document Server

    Billan, J; Musso, A; Remondino, Vittorio

    2002-01-01

    Field measuring systems operating at room temperature have been installed on each magnet manufacturers' premises in order to validate the integrated field gradient and the field quality (harmonics). The aim of the systems is also to verify the quality of the collared coils in their earliest state in order to correct the assembly process in case of defect. The device consists of a sensitive measuring probe, a data acquisition system and an on-line analysis program. The magnets are powered with low current to avoid excessive heating and voltages across the normal conducting coils hence the magnetic probes must be very sensitive. The program gives results instantly to fit production requirements. This paper describes the measuring system, the method adopted and the performance observed based on the results of the magnetic measurements.

  16. High Throughput Cryogenic And Room Temperature Testing Of Focal Plane Components

    Science.gov (United States)

    Voynick, Stanley

    1988-04-01

    To increase production efficiency in the manufacture of infrared focal plane components, test techniques were refined to enhance testing throughput and accuracy. The result is an integrated package of high performance hardware and software tools which performs well in high throughput production environments. The test system is also very versatile. It has been used for readout (multiplexer) device characterization, room temperature automated wafer probing, and focal plane array (FPA) testing. Tests have been performed using electrical and radiometric optical stimulus. An integrated, convenient software package was developed and is used to acquire, reduce, analyze, display, and archive test data. The test software supports fully automated operation for the production environment, as well as menu-driven operation for R&D, characterization and setup purposes. Trade-offs between handling techniques in cryogenic production testing were investigated. " atch processing" is preferred over "continuous flow", primarily due to considerations of contamination of the cryogenic environment.

  17. Highly transparent conductive ITO/Ag/ITO trilayer films deposited by RF sputtering at room temperature

    Directory of Open Access Journals (Sweden)

    Ningyu Ren

    2017-05-01

    Full Text Available ITO/Ag/ITO (IAI trilayer films were deposited on glass substrate by radio frequency magnetron sputtering at room temperature. A high optical transmittance over 94.25% at the wavelength of 550 nm and an average transmittance over the visual region of 88.04% were achieved. The calculated value of figure of merit (FOM reaches 80.9 10-3 Ω-1 for IAI films with 15-nm-thick Ag interlayer. From the morphology and structural characterization, IAI films could show an excellent correlated electric and optical performance if Ag grains interconnect with each other on the bottom ITO layer. These results indicate that IAI trilayer films, which also exhibit low surface roughness, will be well used in optoelectronic devices.

  18. Transparent conductive ITO/Cu/ITO films prepared on flexible substrates at room temperature

    Science.gov (United States)

    Ding, Xingwei; Yan, Jinliang; Li, Ting; Zhang, Liying

    2012-01-01

    Transparent conductive ITO/Cu/ITO films were deposited on PET substrates by magnetron sputtering using three cathodes at room temperature. Effects of the SiO2 buffer layer and thickness of Cu interlayer on the structural, electrical and optical properties of ITO/Cu/ITO films were investigated. The optical transmittance was affected slightly by SiO2 buffer layer, but the electrical properties of ITO/Cu/ITO films were improved. The transmittance and resistivity of the SiO2/ITO/Cu/ITO films decrease as the Cu layer thickness increases. The ITO/Cu/ITO film with 5 nm Cu interlayer deposited on the 40 nm thick SiO2 buffer layer exhibits the sheet resistance of 143 Ω/sq and transmittance of 65% at 550 nm wavelength. The optical and electrical properties of the ITO/Cu/ITO films were mainly dependent on the Cu layer.

  19. Ultrastable measurement platform: sub-nm drift over hours in 3D at room temperature.

    Science.gov (United States)

    Walder, Robert; Paik, D Hern; Bull, Matthew S; Sauer, Carl; Perkins, Thomas T

    2015-06-29

    Advanced optical traps can probe single molecules with Ångstrom-scale precision, but drift limits the utility of these instruments. To achieve Å-scale stability, a differential measurement scheme between a pair of laser foci was introduced that substantially exceeds the inherent mechanical stability of various types of microscopes at room temperature. By using lock-in detection to measure both lasers with a single quadrant photodiode, we enhanced the differential stability of this optical reference frame and thereby stabilized an optical-trapping microscope to 0.2 Å laterally over 100 s based on the Allan deviation. In three dimensions, we achieved stabilities of 1 Å over 1,000 s and 1 nm over 15 h. This stability was complemented by high measurement bandwidth (100 kHz). Overall, our compact back-scattered detection enables an ultrastable measurement platform compatible with optical traps, atomic force microscopy, and optical microscopy, including super-resolution techniques.

  20. Enhanced and selective ammonia sensing of reduced graphene oxide based chemo resistive sensor at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ramesh, E-mail: rameshphysicsdu@gmail.com; Kaur, Amarjeet, E-mail: amarkaur@physics.du.ac.in [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

    2016-05-06

    The reduced graphene oxide thin films were fabricated by using the spin coating method. The reduced graphene oxide samples were characterised by Raman studies to obtain corresponding D and G bands at 1360 and 1590 cm{sup −1} respectively. Fourier transform infra-red (FTIR) spectra consists of peak corresponds to sp{sup 2} hybridisation of carbon atoms at 1560 cm{sup −1}. The reduced graphene oxide based chemoresistive sensor exhibited a p-type semiconductor behaviour in ambient conditions and showed good sensitivity to different concentration of ammonia from 25 ppm to 500 ppm and excellent selectivity at room temperature. The sensor displays selectivity to several hazardous vapours such as methanol, ethanol, acetone and hydrazine hydrate. The sensor demonstrated a sensitivity of 9.8 at 25 ppm concentration of ammonia with response time of 163 seconds.

  1. Room temperature detection of NO2 using InSb nanowire

    Science.gov (United States)

    Paul, Rajat Kanti; Badhulika, Sushmee; Mulchandani, Ashok

    2011-07-01

    Room temperature detection of NO2 down to one part-per-million (ppm) using single crystalline n-type InSb nanowires (NWs) chemiresistive gas sensor is presented. These sensors were synthesized and fabricated by the combination of chemical vapor deposition and dielectrophoresis alignment techniques. The sensor devices showed an increase in resistance upon exposure to successive increments of NO2 concentration up to 10 ppm. The reduction in conductance of n-type InSb NWs when exposed to NO2 is made possible due to the charge transfer from the InSb NW surface to the adsorbed electron acceptor NO2 molecules. The demonstrated results suggest InSb NW as a promising candidate in sensing applications as well as being environmental friendly over existing arsenic and/or phosphorous-based III-V NW sensors.

  2. Room-temperature, atmospheric plasma needle reduces adenovirus gene expression in HEK 293A host cells

    Science.gov (United States)

    Xiong, Z.; Lu, X.; Cao, Y.; Ning, Q.; Ostrikov, K.; Lu, Y.; Zhou, X.; Liu, J.

    2011-12-01

    Room-temperature, atmospheric-pressure plasma needle treatment is used to effectively minimize the adenovirus (AdV) infectivity as quantified by the dramatic reduction of its gene expression in HEK 293A primary human embryonic kidney cells studied by green fluorescent protein imaging. The AdV titer is reduced by two orders of magnitude within only 8 min of the plasma exposure. This effect is due to longer lifetimes and higher interaction efficacy of the plasma-generated reactive species in confined space exposed to the plasma rather than thermal effects commonly utilized in pathogen inactivation. This generic approach is promising for the next-generation anti-viral treatments and imunotherapies.

  3. Force-detected nanoscale absorption spectroscopy in water at room temperature using an optical trap

    Science.gov (United States)

    Parobek, Alexander; Black, Jacob W.; Kamenetska, Maria; Ganim, Ziad

    2018-04-01

    Measuring absorption spectra of single molecules presents a fundamental challenge for standard transmission-based instruments because of the inherently low signal relative to the large background of the excitation source. Here we demonstrate a new approach for performing absorption spectroscopy in solution using a force measurement to read out optical excitation at the nanoscale. The photoinduced force between model chromophores and an optically trapped gold nanoshell has been measured in water at room temperature. This photoinduced force is characterized as a function of wavelength to yield the force spectrum, which is shown to be correlated to the absorption spectrum for four model systems. The instrument constructed for these measurements combines an optical tweezer with frequency domain absorption spectroscopy over the 400-800 nm range. These measurements provide proof-of-principle experiments for force-detected nanoscale spectroscopies that operate under ambient chemical conditions.

  4. Room temperature ionic liquids in actinide separations: extraction, chromatography and complexation studies

    International Nuclear Information System (INIS)

    Mohapatra, P.K.

    2017-01-01

    In view of their large inventory and high radiotoxicities, actinide ion separation has great relevance in the safe management of radioactive wastes. Though solvent extraction based processes using molecular diluents are routinely used for actinide ion separations in nuclear fuel cycle activities, room temperature ionic liquid (RTIL) based diluents are becoming increasingly popular due to factors such as more efficient extraction, higher metal loading, higher radiation resistance, etc. The fascinating chemistry of the actinide ions in the RTIL based solvent systems due to complex extraction mechanisms makes it a challenging area of research. By suitable tuning of the cationic and anionic parts of the ionic liquids their physical properties such as density, dielectric constant and viscosity can be changed which are considered important in metal ion extraction. Studies on the complexation of the metal ions of interest in ionic liquids are needed to explain some unusually high extraction seen in RTILs. (author)

  5. Quantitative experimental assessment of hot carrier-enhanced solar cells at room temperature

    Science.gov (United States)

    Nguyen, Dac-Trung; Lombez, Laurent; Gibelli, François; Boyer-Richard, Soline; Le Corre, Alain; Durand, Olivier; Guillemoles, Jean-François

    2018-03-01

    In common photovoltaic devices, the part of the incident energy above the absorption threshold quickly ends up as heat, which limits their maximum achievable efficiency to far below the thermodynamic limit for solar energy conversion. Conversely, the conversion of the excess kinetic energy of the photogenerated carriers into additional free energy would be sufficient to approach the thermodynamic limit. This is the principle of hot carrier devices. Unfortunately, such device operation in conditions relevant for utilization has never been evidenced. Here, we show that the quantitative thermodynamic study of the hot carrier population, with luminance measurements, allows us to discuss the hot carrier contribution to the solar cell performance. We demonstrate that the voltage and current can be enhanced in a semiconductor heterostructure due to the presence of the hot carrier population in a single InGaAsP quantum well at room temperature. These experimental results substantiate the potential of increasing photovoltaic performances in the hot carrier regime.

  6. Graphene field-effect transistors as room-temperature terahertz detectors

    Science.gov (United States)

    Vicarelli, L.; Vitiello, M. S.; Coquillat, D.; Lombardo, A.; Ferrari, A. C.; Knap, W.; Polini, M.; Pellegrini, V.; Tredicucci, A.

    2012-10-01

    The unique optoelectronic properties of graphene make it an ideal platform for a variety of photonic applications, including fast photodetectors, transparent electrodes in displays and photovoltaic modules, optical modulators, plasmonic devices, microcavities, and ultra-fast lasers. Owing to its high carrier mobility, gapless spectrum and frequency-independent absorption, graphene is a very promising material for the development of detectors and modulators operating in the terahertz region of the electromagnetic spectrum (wavelengths in the hundreds of micrometres), still severely lacking in terms of solid-state devices. Here we demonstrate terahertz detectors based on antenna-coupled graphene field-effect transistors. These exploit the nonlinear response to the oscillating radiation field at the gate electrode, with contributions of thermoelectric and photoconductive origin. We demonstrate room temperature operation at 0.3 THz, showing that our devices can already be used in realistic settings, enabling large-area, fast imaging of macroscopic samples.

  7. Trapping of hydrogen atoms in X-irradiated salts at room temperature and the decay kinetics

    Science.gov (United States)

    May, C. E.; Philipp, W. H.; Marsik, S. J.

    1974-01-01

    The salts (hypophosphites, formates, a phosphite, a phosphate, and an oxalate) were X-irradiated, whereby hydrogen formed chemically by a radiolytic process becomes trapped in the solid. By room temperature vacuum extraction, the kinetics for the evolution of this trapped hydrogen was studied mass spectrometrically. All salts except two exhibited second-order kinetics. The two exceptions (NaH2PO2(H2O) and K2HPO4) showed first-order kinetics. Based on experimental results, the escape of hydrogen involves three steps: the diffusion of hydrogen atoms from the bulk to the surface, association of these atoms on the surface (rate controlling step for second-order hydrogen evolution), and the desorption of molecular hydrogen from the surface. The hydrogen does not escape if the irradiated salt is stored in air, apparently because adsorbed air molecules occupy surface sites required in the escape mechanism.

  8. Crystalline Structure, Defect Chemistry and Room Temperature Colossal Permittivity of Nd-doped Barium Titanate.

    Science.gov (United States)

    Sun, Qiaomei; Gu, Qilin; Zhu, Kongjun; Jin, Rongying; Liu, Jinsong; Wang, Jing; Qiu, Jinhao

    2017-02-13

    Dielectric materials with high permittivity are strongly demanded for various technological applications. While polarization inherently exists in ferroelectric barium titanate (BaTiO 3 ), its high permittivity can only be achieved by chemical and/or structural modification. Here, we report the room-temperature colossal permittivity (~760,000) obtained in xNd: BaTiO 3 (x = 0.5 mol%) ceramics derived from the counterpart nanoparticles followed by conventional pressureless sintering process. Through the systematic analysis of chemical composition, crystalline structure and defect chemistry, the substitution mechanism involving the occupation of Nd 3+ in Ba 2+ -site associated with the generation of Ba vacancies and oxygen vacancies for charge compensation has been firstly demonstrated. The present study serves as a precedent and fundamental step toward further improvement of the permittivity of BaTiO 3 -based ceramics.

  9. Novel copper redox-based cathode materials for room-temperature sodium-ion batteries

    Science.gov (United States)

    Xu, Shu-Yin; Wu, Xiao-Yan; Li, Yun-Ming; Hu, Yong-Sheng; Chen, Li-Quan

    2014-11-01

    Layered oxides of P2-type Na0.68Cu0.34Mn0.66O2, P2-type Na0.68Cu0.34Mn0.50Ti0.16O2, and O'3-type NaCu0.67Sb0.33O2 were synthesized and evaluated as cathode materials for room-temperature sodium-ion batteries. The first two materials can deliver a capacity of around 70 mAh/g. The Cu2+ is oxidized to Cu3+ during charging, and the Cu3+ goes back to Cu2+ upon discharging. This is the first demonstration of the highly reversible change of the redox couple of Cu2+/Cu3+ with high storage potential in secondary batteries.

  10. Stress induced martensite transformation in Co–28Cr–6Mo alloy during room temperature deformation

    Energy Technology Data Exchange (ETDEWEB)

    Cai, S., E-mail: song_cai@fwmetals.com [Fort Wayne Metals Research Products Corporation, 9609 Ardmore Avenue, Fort Wayne, IN 46809 (United States); Daymond, M.R. [Department of Mechanical and Materials Engineering, Queen' s University, Nicol Hall, 60 Union Street, Kingston, Ontario, Canada K7L 3N6 (Canada); Ren, Y. [Advanced Photon Source, Argonne National Laboratory, 9700S. Cass Avenue, 433/D008, Argonne, IL 60439 (United States)

    2013-09-15

    The phase transformation and texture change of two Co–28Cr–6Mo alloys during room temperature deformation were studied by using the in-situ synchrotron X-ray diffraction. It is found that a slight difference in chemical compositions can significantly change the phase constitutions and the mechanical properties. For the material with less Ni, C and N (lower α-phase stability), increasing the grain size promotes the athermal martensite transformation during cooling. The kinetics of the Stress Induced Martensite (SIM) phase transformation may be more affected by the athermal martensite instead of the grain size of the α-phase. After deformation, similar textures are produced in samples regardless the differences in the initial structures such as the phase constitution and the grain size; while a relatively strong {111} texture and a weak {100} texture are produced in the α-phase, a {101"¯1} fiber texture is gradually developed in the ε-phase during uniaxial tension.

  11. Controlled damaging and repair of self-organized nanostructures by atom manipulation at room temperature

    International Nuclear Information System (INIS)

    Gurlu, O; Houselt, A van; Thijssen, W H A; Ruitenbeek, J M van; Poelsema, B; Zandvliet, H J W

    2007-01-01

    The possibility of controlled local demolition and repair of the recently discovered self-organized Pt nanowires on Ge(001) surfaces has been explored. These nanowires are composed of Pt dimers, which are found to be rather weakly bound to the underlying substrate. Using this property, we demonstrate the possibility of carrying the constituting dimers of the Pt nanowires from point to point with atomic precision at room temperature. Pt dimers can be picked-up in two configurations: (i) a horizontal configuration at the tip apex, resulting in double tip images and (ii) a configuration where the Pt dimer is attached to the side of the tip apex, resulting in well-defined atomically resolved images

  12. Room Temperature, High-yield Synthesis of Block Copolymer-mediated Gold Nanoparticles

    Science.gov (United States)

    Ray, Debes; Aswal, V. K.; Kohlbrecher, J.

    2010-12-01

    We report the high-yield synthesis of gold nanoparticles in block copolymer-mediated synthesis where the nanoparticles have been synthesized from hydrogen tetrachloroaureate (III) hydrate (HAuCl4ṡ3H2O) using P85 (EO26PO39EO26) block copolymers in aqueous solution at room temperature. The formation of gold nanoparticles in these systems has been confirmed by UV-visible spectroscopy. The yield of nanoparticles simply does not increase with the increase in the gold salt concentration, which is limited by the gold ions reduction. Therefore, we have used the presence of additional reductant (tri-sodium citrate) to enhance the yield by manifold. The size distribution of the nanoparticles has been obtained by small-angle neutron scattering (SANS) and the average size is found to increase with the yield.

  13. Efficient room temperature spin-Hall injection across an oxide barrier

    International Nuclear Information System (INIS)

    Chen, Shuhan; Qin, Chuan; Ji, Yi

    2014-01-01

    Spin Hall injection is demonstrated at room temperature using Pt metal and AlO x barriers. A substantial spin accumulation, comparable to that of a magnetic spin injection, is transferred into a mesoscopic Cu wire from an adjacent Pt wire across an AlO x barrier. The Pt spin Hall angle is 0.030 ± 0.007 when assuming a Pt spin diffusion length λ pt  > 6 nm and 0.09 ± 0.02 when assuming λ pt  = 2 nm. Nearly (66 ± 6)% of the spin accumulation on the Pt surface is transferred into the Cu across the AlO x , enabling an efficient spin Hall injection scheme.

  14. Mechanical and Thermal Properties of Unsaturated Polyester/Vinyl Ester Blends Cured at Room Temperature

    Science.gov (United States)

    Ardhyananta, H.; Puspadewa, F. D.; Wicaksono, S. T.; Widyastuti; Wibisono, A. T.; Kurniawan, B. A.; Ismail, H.; Salsac, A. V.

    2017-05-01

    Unsaturated polyester (UP) resin containing aromatic ring was blended with vinyl ester (VE) at wide range composition (10, 20, 30, 40,and 80 wt.%) using mechanical blending method. The blends were cured at room temperature using methyl ethyl ketone peroxide (MEKP) (4 wt.%) as catalyst initiator without the presence of catalystaccelerator. The effect of vinyl ester composition on theenhancement of mechanical and thermal properties of unsaturated polyester/vinyl ester blends was investigated. The polymer blends were characterized by Fourier Transform Infra Red (FTIR)spectroscopy, tensile testing, hardness testing, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). IR spectra showed UP and VE peaks. The curing copolymerization reactionoccurred at vinyl (C=C) bonds. The addition of vinyl esters enhanced mechanical and thermal properties. The UP/VE blends showed homogeneous morphology, transparent and copolymer thermoset blend.

  15. Simultaneous Femtosecond X-ray Spectroscopy and Diffraction of Photosystem II at Room Temperature

    Science.gov (United States)

    Kern, Jan; Alonso-Mori, Roberto; Tran, Rosalie; Hattne, Johan; Gildea, Richard J.; Echols, Nathaniel; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G.; Lassalle-Kaiser, Benedikt; Koroidov, Sergey; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dörte; Milathianaki, Despina; Fry, Alan R.; Miahnahri, Alan; Schafer, Donald W.; Messerschmidt, Marc; Seibert, M. Marvin; Koglin, Jason E.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J.; Grosse-Kunstleve, Ralf W.; Zwart, Petrus H.; White, William E.; Glatzel, Pieter; Adams, Paul D.; Bogan, Michael J.; Williams, Garth J.; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Sauter, Nicholas K.; Yachandra, Vittal K.; Bergmann, Uwe; Yano, Junko

    2013-01-01

    Intense femtosecond X-ray pulses produced at the Linac Coherent Light Source (LCLS) were used for simultaneous X-ray diffraction (XRD) and X-ray emission spectroscopy (XES) of microcrystals of Photosystem II (PS II) at room temperature. This method probes the overall protein structure and the electronic structure of the Mn4CaO5 cluster in the oxygen-evolving complex of PS II. XRD data are presented from both the dark state (S1) and the first illuminated state (S2) of PS II. Our simultaneous XRD/XES study shows that the PS II crystals are intact during our measurements at the LCLS, not only with respect to the structure of PS II, but also with regard to the electronic structure of the highly radiation sensitive Mn4CaO5 cluster, opening new directions for future dynamics studies. PMID:23413188

  16. Understanding the Room Temperature Ferromagnetism in GaN Nanowires with Pd Doping

    Energy Technology Data Exchange (ETDEWEB)

    Manna, S; De, S K, E-mail: mannaju@gmail [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)

    2011-04-01

    We report the first synthesis and characterization of 4d transition metal palladium-doped GaN nanowires (NWs). Room temperature ferromagnetism has been observed in high quality Vapor Liquid Solid (VLS) epitaxy grown undoped n-type GaN nanowires. It was proposed that this type of magnetism is due to defects which are not observed in Bulk GaN because of large formation energy of defects in bulk GaN. Here we have successfully doped 4d transition metal Pd in GaN NWs. We find fairly strong and long-range ferromagnetic coupling between Pd substituted for Ga in GaN . The results suggest that 4d metals such as Pd may also be considered as candidates for ferromagnetic dopants in semiconductors.

  17. The effect of Sodium hydroxide catalyst in formation of Ni nanoparticles at room temperature

    International Nuclear Information System (INIS)

    Shahbahrami, N.; Reyhani, A.; Afshari, N.; Mortazavi, Z.; Norouzian, Sh.; Hojabri, A.; Novinrooz, A. J.

    2007-01-01

    In this paper, Ni nanoparticles growth is studies by spontaneous auto catalytic reduction in an alcohol- water solution in present NaOH catalysis with various ratio at room temperature. The scanning electron microscopy and XRD analyses have been used for investigation diameter and structure of Ni nanoparticles. Investigation of the analyses show that have not formed Ni Nanoparticles in Ph values 8, 9, 10 and 13, but in Ph values 11 and 12 have formed Ni Nanoparticles with average diameter of about 65 and 90 nm, respectively. The XRD patterns show that samples have face-centered cubic structure with (111),(200).(222) planes. The results show that sodium hydroxide value is very effect on the Ni nanoparticles growth.

  18. Glancing angle deposition of sculptured thin metal films at room temperature

    Science.gov (United States)

    Liedtke, S.; Grüner, Ch; Lotnyk, A.; Rauschenbach, B.

    2017-09-01

    Metallic thin films consisting of separated nanostructures are fabricated by evaporative glancing angle deposition at room temperature. The columnar microstructure of the Ti and Cr columns is investigated by high resolution transmission electron microscopy and selective area electron diffraction. The morphology of the sculptured metallic films is studied by scanning electron microscopy. It is found that tilted Ti and Cr columns grow with a single crystalline morphology, while upright Cr columns are polycrystalline. Further, the influence of continuous substrate rotation on the shaping of Al, Ti, Cr and Mo nanostructures is studied with view to surface diffusion and the shadowing effect. It is observed that sculptured metallic thin films deposited without substrate rotation grow faster compared to those grown with continuous substrate rotation. A theoretical model is provided to describe this effect.

  19. Chronic Inflammation in an Anophthalmic Socket due to a Room Temperature Vulcanized Silicone Implant

    Directory of Open Access Journals (Sweden)

    Alicia Galindo-Ferreiro

    2016-04-01

    Full Text Available Two case reports are used to illustrate the signs and symptoms, complications and treatments of chronic socket inflammation due to intraorbital implants. The ophthalmic examination, surgeries and treatments are documented. Two anophthalmic cases that underwent enucleation and multiple orbital surgeries to enhance the anophthalmic socket volume developed pain, intense discharge and contracted cavities with chronic inflammation in the socket which was nonresponsive to medical therapy. Computed tomography indicated a hypodense foreign body in both cases causing an intense inflammatory reaction. The implants were removed by excisional surgery and a room temperature vulcanized silicone implant was retrieved in both cases. Socket inflammation resolved in both cases after implant removal. An intraorbital inflammatory reaction against an intraorbital implant can cause chronic socket inflammation in patients with a history of multiple surgeries. Diagnosis requires imaging and the definitive treatment is implant removal.

  20. Scaling of dynamical decoupling for a single electron spin in nanodiamonds at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dong-Qi; Liu, Gang-Qin; Chang, Yan-Chun; Pan, Xin-Yu, E-mail: xypan@aphy.iphy.ac.cn

    2014-01-01

    Overcoming the spin qubit decoherence is a challenge for quantum science and technology. We investigate the decoherence process in nanodiamonds by Carr–Purcell–Meiboom–Gill (CPMG) technique at room temperature. We find that the coherence time T{sub 2} scales as n{sup γ}. The elongation effect of coherence time can be represented by a constant power of the number of pulses n. Considering the filter function of CPMG decoupling sequence as a δ function, the spectrum density of noise has been reconstructed directly from the coherence time measurements and a Lorentzian noise power spectrum model agrees well with the experiment. These results are helpful for the application of nanodiamonds to nanoscale magnetic imaging.