Spontaneous quasi-periodic current self-oscillations in a weakly coupled GaAs/(Al,Ga)As superlattice at room temperature

2013 ◽  
Vol 102 (24) ◽  
pp. 242107 ◽  
Author(s):  
Yuyang Huang ◽  
Wen Li ◽  
Wenquan Ma ◽  
Hua Qin ◽  
Holger T. Grahn ◽  
...  
Keyword(s):  
Room Temperature ◽  
Weakly Coupled ◽  
Periodic Current

scholarly journals Bidirectional mid-infrared communications between two identical macroscopic graphene fibres

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Bo Fang ◽  
Srikrishna Chanakya Bodepudi ◽  
Feng Tian ◽  
Xinyu Liu ◽  
Dan Chang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cryogenic Cooling ◽  
Mid Infrared ◽  
Graphene Layers ◽  
Sensing Systems ◽  
Weakly Coupled ◽  
Remote Sensing Systems ◽  
Infrared Communications ◽  
Low Performance ◽  
Set Up

AbstractAmong light-based free-space communication platforms, mid-infrared (MIR) light pertains to important applications in biomedical engineering, environmental monitoring, and remote sensing systems. Integrating MIR generation and reception in a network using two identical devices is vital for the miniaturization and simplification of MIR communications. However, conventional MIR emitters and receivers are not bidirectional due to intrinsic limitations of low performance and often require cryogenic cooling. Here, we demonstrate that macroscopic graphene fibres (GFs) assembled from weakly-coupled graphene layers allow room-temperature MIR detection and emission with megahertz modulation frequencies due to the persistence of photo-thermoelectric effect in millimeter-length and the ability to rapidly modulate gray-body radiation. Based on the dual-functionality of GFs, we set up a system that conducts bidirectional data transmission by switching modes between two identical GFs. The room-temperature operation of our systems and the potential to produce GFs on industrial textile-scale offer opportunities for simplified and wearable optical communications.

Tarnishing film-induced brittle cracking of brass

2009 ◽  
Vol 24 (7) ◽  
pp. 2409-2415 ◽  
Author(s):  
Cheng Zhang ◽  
Yan Jing Su ◽  
Li Jie Qiao ◽  
Wu Yang Chu
Keyword(s):  
Room Temperature ◽  
Film Rupture ◽  
Galvanic Current ◽  
Ductile Mode ◽  
Brass Surface ◽  
Strain Rate Loading ◽  
Periodic Current ◽  
Brass Sample ◽  
Initial Cracks ◽  
Deposited Film

Tarnishing film was developed on the brass surface in Mattsson's solution at room temperature. The filmed brass was removed from the solution, dried, and subjected to a slow strain rate (loading speed = 0.5 mm/min) in air for studying the effect of the film on crack propagation in the brass substrate. It was observed that initial cracks started to emerge in the film and then propagated to the brass matrix in a brittle intergranular manner. However, it changed into a ductile mode after removing the deposited film. The galvanic current between platinum wire and filmed brass sample in Mattson's solution was investigated. The results showed that periodic current fluctuations were observed when the sample was under a constant applied load. These observations showed that the film rupture-formation occurred at cracks under the stress-corrosion cracking condition.

Microwave Tuning Quality and Power Handling of Voltage-Tunable Capacitors: Semiconductor Varactors Versus Ba1−xSrxTiO3 Films

1997 ◽  
Vol 493 ◽  
Author(s):  
D. Gait ◽  
T. Rivkina ◽  
M. W. Cromar
Keyword(s):  
Room Temperature ◽  
Frequency Dispersion ◽  
Microwave Frequency ◽  
Third Order ◽  
Resonant Frequencies ◽  
Tunable Capacitors ◽  
Distortion Products ◽  
Power Handling ◽  
Weakly Coupled ◽  
Microstrip Resonators

ABSTRACTThin films of SrTiO3 and Ba0.4Sr0.6TiO3 have been pulse laser ablated onto LaAIO3 substrates. Normal metal coplanar capacitor electrodes were patterned on top of these films and the capacitors were incorporated into weakly coupled microstrip resonators. Resonant frequencies and Q's were measured as a function of bias at room temperature and at 77 K. The microwave frequency capacitance and loss is calculated from the resonant properties and compared with the simultaneously measured 1 MHz capacitance and dissipation. Two-tone intermodulation distortion products were measured and the third-order intercept is referenced to the microwave voltage across the capacitors. Commercially available semiconductor varactors were tested in a similar manner. The tuning quality (the ratio of the relative capacitance tuning to dissipation), frequency dispersion, and power handling of these capacitors are compared. Although there appears to be no intrinsic power handling advantage of the paraelectrics over the semiconductor varactors, the paraelectric varactors can offer better tuning quality.

scholarly journals Single-Shot Readout of a Nuclear Spin Weakly Coupled to a Nitrogen-Vacancy Center at Room Temperature

2017 ◽  
Vol 118 (15) ◽  
Author(s):  
Gang-Qin Liu ◽  
Jian Xing ◽  
Wen-Long Ma ◽  
Ping Wang ◽  
Chang-Hao Li ◽  
...  
Keyword(s):  
Nuclear Spin ◽  
Room Temperature ◽  
Nitrogen Vacancy ◽  
Single Shot ◽  
Nitrogen Vacancy Center ◽  
Weakly Coupled ◽  
Vacancy Center

Magnetic Properties of Microcrystalline Poly(Phenyl- Diacetylenes) Carrying Radical or Carbene Centers on the Side Chains

1989 ◽  
Vol 173 ◽  
Author(s):  
Noboru Koga ◽  
Katsuya Inoue ◽  
Noriko Sasagawa ◽  
Hiizu Iwamura
Keyword(s):  
Cryogenic Temperature ◽  
Room Temperature ◽  
X Ray ◽  
Spontaneous Polymerization ◽  
Weakly Coupled ◽  
Two Samples ◽  
Phenyl Rings ◽  
Insoluble Polymer ◽  
Polymeric Samples ◽  
Triplet Carbene

ABSTRACT1-Phenyl-l,3-butadiyne derivatives (3 and 4) carrying stable t-butylnitroxide and diazomethyl groups, respectively, have been prepared. Mixed crystals of 3 and the corresponding hydroxylamine 2 (x003c:1:1) polymerized in the solid state at 100°C to give black-violet microcrystals with a metallic luster. A microcrystalline sample of 4 underwent spontaneous polymerization at room temperature when crystallized to give an insoluble polymer which was then photolyzed at cryogenic temperature to generate triplet carbene centers attached to the phenyl rings of the poly(phenyldiacetylene). Some of these microcrystalline polymeric samples were responsive to a magnet at room temperature. Magnetic susceptibility measurements on the two samples revealed only weakly coupled independent spins Hydrogen bonding between the polydiacetylene chains as estimated by X-ray crystal structure of 2 is expected to be effective for increasing the dimension of the spin alignment.

scholarly journals Dielectric Anomaly and Charge Fluctuations in the Non-Magnetic Dimer Mott Insulator λ-(BEDT-STF)2GaCl4

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1031
Author(s):  
Olga Iakutkina ◽  
Roland Rosslhuber ◽  
Atsushi Kawamoto ◽  
Martin Dressel
Keyword(s):  
Room Temperature ◽  
Magnetic Order ◽  
Optical Measurement ◽  
Vibrational Mode ◽  
Mott Insulator ◽  
Organic Conductors ◽  
Spin Liquid ◽  
Temperature Dependent ◽  
Weakly Coupled ◽  
A Charge

The dimer Mott insulator λ-(BEDT-STF)2GaCl4 undergoes no magnetic order down to the lowest temperatures, suggesting the formation of a novel quantum disordered state. Our frequency and temperature-dependent investigations of the dielectric response reveal a relaxor-like behavior below T≈100 K for all three axes, similar to other spin liquid candidates. Optical measurement of the charge-sensitive vibrational mode ν27(b1u) identifies a charge disproportionation Δρ≈0.04e on the dimer that exists up to room temperature and originates from inequivalent molecules in the weakly coupled dimers. The linewidth of the charge sensitive mode is broader than that of typical organic conductors, supporting the existence of a disordered electronic state.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Hepatocyte Alterations in Guinea Pigs FED Polychlorinated Biphenyls (PCBs), Dibenzodioxins (PCDD), AND DIBENZOFURANS (PCDF)

1982 ◽  
Vol 40 ◽  
pp. 56-57
Author(s):  
J. N. Turner ◽  
D. N. Collins
Keyword(s):  
Guinea Pigs ◽  
Room Temperature ◽  
Dose Group ◽  
Methyl Cellulose ◽  
Uranyl Acetate ◽  
Target Organ ◽  
Office Building ◽  
Lead Citrate ◽  
Control Groups ◽  
Cooling Fluid

A fire involving an electric service transformer and its cooling fluid, a mixture of PCBs and chlorinated benzenes, contaminated an office building with a fine soot. Chemical analysis showed PCDDs and PCDFs including the highly toxic tetra isomers. Guinea pigs were chosen as an experimental animal to test the soot's toxicity because of their sensitivity to these compounds, and the liver was examined because it is a target organ. The soot was suspended in 0.75% methyl cellulose and administered in a single dose by gavage at levels of 1,10,100, and 500mgm soot/kgm body weight. Each dose group was composed of 6 males and 6 females. Control groups included 12 (6 male, 6 female) animals fed activated carbon in methyl cellulose, 6 males fed methyl cellulose, and 16 males and 10 females untreated. The guinea pigs were sacrificed at 42 days by suffocation in CO2. Liver samples were immediately immersed and minced in 2% gluteraldehyde in cacadylate buffer at pH 7.4 and 4°C. After overnight fixation, samples were postfixed in 1% OsO4 in cacodylate for 1 hr at room temperature, embedded in epon, sectioned and stained with uranyl acetate and lead citrate.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

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