Preparation and Properties of Amorphous Tl2SexTe1−x Films

1974 ◽  
Vol 52 (2) ◽  
pp. 187-192 ◽  
Author(s):  
J. J. Harris ◽  
D. E. Brodie ◽  
P. C. Eastman
Keyword(s):  
Low Temperature ◽  
Liquid Nitrogen ◽  
Growth Temperature ◽  
Activation Energies ◽  
Amorphous Semiconductors ◽  
Compositional Dependence ◽  
Flash Evaporation ◽  
Thermally Activated ◽  
Temperature Ranges ◽  
Temperature Conduction

Films of amorphous Tl2SexTe1−x, with x values of 0, 0.25, 0.5, 0.75, and 1, have been prepared by flash evaporation of mixed powders of Tl2Se and Tl2Te. These films show thermally activated conduction with up to four distinct activation energies, in different temperature ranges, as the samples are warmed from their liquid-nitrogen growth temperature; they then undergo spontaneous recrystallization at temperatures near 300 K. The low-temperature conduction in these samples is consistent with the model of amorphous semiconductors proposed by Davis and Mott, and the compositional dependence of the parameters of this model are presented and discussed.

Low Temperature Testing of Ultrasound Sensors in Liquid Nitrogen

2021 ◽  
Author(s):  
Joseph Chul Chung ◽  
Michael Myung-Sub Lee ◽  
Sejong Chun ◽  
Inseok Yang
Keyword(s):  
Low Temperature ◽  
Liquid Nitrogen ◽  
Flow Measurement ◽  
Temperature Scale ◽  
Fiber Optic ◽  
Measurement Techniques ◽  
Fiber Optic Sensors ◽  
Ultrasound Waves ◽  
Flow Metering ◽  
Temperature Ranges

Abstract Ultrasonic flow metering is one of flow measurement techniques applicable to low temperature environment. Unlike pipe provers or Coriolis mass flowmeters, ultrasonic flowmeters require waveguides in front of ultrasound sensors. The waveguides can prevent heat conduction from the ultrasound sensors to low temperature liquids, such as liquid nitrogen. The ultrasound sensors can maintain its piezoelectricity within the specified temperature ranges by thermal insulation of the waveguides. In this study, low temperature testing on a pair of ultrasound sensors was performed to see if ultrasound waves could be transmitted normally through liquid nitrogen. A flowmeter cell with diameter of 300 mm (equivalently, 12”) was used as a container for liquid nitrogen. Three pairs of ultrasound sensors were installed in the flowmeter cell. Fiber-optic sensors were also attached on its inner wall to measure the temperature of liquid nitrogen. As a result, ultrasound waves were successfully transmitted between a pair of ultrasound sensors by using a preamplifier. The fiber-optic sensors could measure the temperature of liquid nitrogen although the sensors were not calibrated by the reference temperature scale at KRISS.

Intracellular structures of rapid frozen biological samples observed by high-resolution low-temperature Scanning Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 736-737
Author(s):  
T. Inoué ◽  
H. Koike
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Liquid Nitrogen ◽  
Specimen Preparation ◽  
Chemical Fixation ◽  
Brown Adipose ◽  
Critical Point Drying ◽  
Temperature Scanning ◽  
Scanning Electron

Low temperature scanning electron microscopy (LTSEM) is useful to avoid artifacts such as deformation and extraction, because specimens are not subjected to chemical fixation, dehydration and critical-point drying. Since Echlin et al developed a LTSEM, many techniques and instruments have been reported for observing frozen materials. However, intracellular structures such as mitochondria and endoplasmic reticulum have been unobservable by the method because of the low resolving power and inadequate specimen preparation methods. Recently, we developed a low temperature SEM that attained high resolutions. In this study, we introduce highly magnified images obtained by the newly developed LTSEM, especially intracellular structures which have been rapidly frozen without chemical fixation.[Specimen preparations] Mouse pancreas and brown adipose tissues (BAT) were used as materials. After the tissues were removed and cut into small pieces, the specimen was placed on a cryo-tip and rapidly frozen in liquid propane using a rapid freezing apparatus (Eiko Engineering Co. Ltd., Japan). After the tips were mounted on the specimen stage of a precooled cryo-holder, the surface of the specimen was manually fractured by a razor blade in liquid nitrogen. The cryo-holder was then inserted into the specimen chamber of the SEM (ISI DS-130), and specimens were observed at the accelerating voltages of 5-8 kV. At first the surface was slightly covered with frost, but intracellular structures were gradually revealed as the frost began to sublimate. Gold was then coated on the specimen surface while tilting the holder at 45-90°. The holder was connected to a liquid nitrogen reservoir by means of a copper braid to maintain low temperature.

scholarly journals Compressive Strength Gain Behavior and Prediction of Cement-Stabilized Macadam at Low Temperature Curing

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yongli Xu ◽  
Guang Yang ◽  
Hongyuan Zhao
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
Curing Temperature ◽  
Strength Development ◽  
Construction Process ◽  
Strength Gain ◽  
Estimation Model ◽  
Maturity Method ◽  
Temperature Ranges ◽  
Natural Temperature

For cement-based materials, the curing temperature determines the strength gain rate and the value of compressive strength. In this paper, the 5% cement-stabilized macadam mixture is used. Three indoor controlled temperature curing and one outdoor natural curing scenarios are designed and implemented to study the strength development scenario law of compressive strength, and they are standard temperature curing (20°C), constant low temperature curing (10°C), day interaction temperature curing (varying from 6°C to 16°C), and one outdoor natural temperature curing (in which the air temperature ranges from 4°C to 20°C). Finally, based on the maturity method, the maturity-strength estimation model is obtained by using and analyzing the data collected from the indoor tests. The model is proved with high accuracy based on the validated results obtained from the data of outdoor tests. This research provides technical support for the construction of cement-stabilized macadam in regions with low temperature, which is beneficial in the construction process and quality control.

scholarly journals Tetragonal–Cubic Phase Transition and Low-Field Dielectric Properties of CH3NH3PbI3 Crystals

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4215
Author(s):  
Roxana E. Patru ◽  
Hamidreza Khassaf ◽  
Iuliana Pasuk ◽  
Mihaela Botea ◽  
Lucian Trupina ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Current Knowledge ◽  
Cubic Phase ◽  
Relaxation Processes ◽  
Temperature Dependent ◽  
Thermally Activated ◽  
Low Field ◽  
Conduction Mechanisms ◽  
Temperature Ranges ◽  
Nyquist Plots

The frequency and temperature dependence of dielectric properties of CH3NH3PbI3 (MAPI) crystals have been studied and analyzed in connection with temperature-dependent structural studies. The obtained results bring arguments for the existence of ferroelectricity and aim to complete the current knowledge on the thermally activated conduction mechanisms, in dark equilibrium and in the presence of a small external a.c. electric field. The study correlates the frequency-dispersive dielectric spectra with the conduction mechanisms and their relaxation processes, as well as with the different transport regimes indicated by the Nyquist plots. The different energy barriers revealed by the impedance spectroscopy highlight the dominant transport mechanisms in different frequency and temperature ranges, being associated with the bulk of the grains, their boundaries, and/or the electrodes’ interfaces.

Study on Low Temperature Conduction Mechanism of Al Doped ZnO/SiO2/ P-Si Heterojunction

2021 ◽  
Vol 904 ◽  
pp. 363-368
Author(s):  
Xiao Yan Zhou ◽  
Bang Sheng Yin
Keyword(s):  
Activation Energy ◽  
Impedance Spectroscopy ◽  
Low Temperature ◽  
Grain Boundaries ◽  
Ac Conductivity ◽  
Spray Pyrolysis Method ◽  
Temperature Conductivity ◽  
Calculated Activation Energy ◽  
Doped Zno ◽  
Temperature Conduction

The 3 at% Al doped ZnO thin films were deposited on p-Si substrate with a native SiO2 layer by spray pyrolysis method. Low temperature conduction behaviors were studied by analysis of impedance spectroscopy and low temperature ac conductivity. The results of impedance spectroscopy showed that the grain boundaries contributed to the resistivity of Al doped ZnO/SiO2/p-Si heterojunction. The calculated activation energy was 0.073 eV for grain boundaries. The equivalent circuit to demonstrate the electrical properties of Al doped ZnO/SiO2/p-Si heterojunction was a series connection of two parallel combination circuits of a resistor and a universal capacitor. Low temperature ac conductivity measurements indicated that the conductivity increased with temperature. Low temperature conductivity mechanism was electron conductivity, and the activation energy was 0.086 eV.

Analysis of Micro Structure and the Resistivity of Cu / Ni Thin Coat as a Low Temperature Sensor Using Electroplating Method Assisted with Magnetic Field outside of the Ion Flow

2021 ◽  
Vol 885 ◽  
pp. 141-147
Author(s):  
Winda Noor Santi ◽  
Moh. Toifur
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Liquid Nitrogen ◽  
Micro Structure ◽  
Medical Field ◽  
Cold Temperatures ◽  
Ion Flow ◽  
Resistance Temperature Detector ◽  
Temperature Detector

Preservation of materials using liquid nitrogen media has been widely used. One of them is used in the medical field, namely cryonic technology. Cryonics is a method of preservation at cold temperatures using a cryoprotectant in liquid nitrogen. To maintain the quality of the material, a sensor that can detect the temperature of liquid nitrogen is needed. Low temperature sensors with Cu and Ni based Resistance Temperature Detector with layers (RTD) have been made, but these sensors have a layer of Ni deposits that are not yet homogeneous. So quality improvement is needed by adding an external magnetic field. Based on this, the aim of this research is to synthesize a thin layer of Cu / Ni using electroplating method assisted by external magnets parallel to the ion currents

scholarly journals Study of low-temperature exposure on biotissue using an elongated cryoapplicator

2021 ◽  
Vol 2103 (1) ◽  
pp. 012049
Author(s):  
A V Pushkarev ◽  
N A Andreev
Keyword(s):  
Atrial Fibrillation ◽  
Data Analysis ◽  
Low Temperature ◽  
Nitrogen Dioxide ◽  
Liquid Nitrogen ◽  
Biological Tissue ◽  
The Novel ◽  
Treatment Data ◽  
Temperature Exposure ◽  
Low Temperature Exposure

Abstract The article presents the results of a study of low-temperature exposure on animal biological tissue using the novel prototype of a liquid nitrogen cryoapplicator. The data obtained are compared with the cryoapplicator characteristics cooled by nitrogen dioxide that are currently used for the atrial fibrillation treatment. Data analysis confirmed the liquid nitrogen cryoapplicators effectiveness and made it possible to highlight their advantages.

scholarly journals Cryopreservation in liquid nitrogen of Brazilian orchid seeds Miltonia flavescens Lindl.

2020 ◽  
Vol 14 ◽  
Author(s):  
Jean Carlo Baudraz de Paula ◽  
Walter Aparecido Ribeiro Júnior ◽  
Gabriel Danilo Shimizu ◽  
Gabriel Barraca Men ◽  
Ricardo Tadeu De Faria
Keyword(s):  
Low Temperature ◽  
Water Content ◽  
Liquid Nitrogen ◽  
Biological Material ◽  
Control Treatment ◽  
Preservation Methods ◽  
Lower Performance ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Protocorm Formation

Miltonia flavescens is a species vulnerable to extinction, which justifies research on preservation methods. Cryopreservation in liquid nitrogen (LN) consists of maintaining biological material at a low-temperature (-196 °C). Thus, the aim of the experiment is to evaluate the influence of different cryoprotective solutions on cryopreservation in LN of the Brazilian orchid Miltonia flavescens seeds. The experiment was conducted in a completely randomized design (CRD), with eight treatments and six replications. The treatments were composed as follows: control; immersion in LN, no cryoprotectant adding; and immersion in LN, with the addition of cryoprotectants: sucrose 0,4 mol L-1; glycerol 2 mol L-1; protection by vitrification in solution (PVS)1; PVS2; PVS2 + 1% phloroglucinol, and PVS3. Except for the control treatment, which was kept in a freezer (10±2 °C), the others remained frozen for 15 days. After this period, the viability of the seeds was evaluated. These seeds were sown and, 30 days after germination, then the frequency of protocorm formation was verified. Before the cryopreservation, the seeds showed 75% viability and 9.5% water content. After cryopreservation, the seeds varied between 67 to 75% viability. However, treatment with glycerol 2 mol L-1 exhibited lower performance than the others (58%). The control treatment showed a higher percentage of protocorm formation (71%) followed by treatments PVS1 (63%), PVS2 (64%), and PVS2PHLO (66%). For the purpose of preserving Miltonia flavescens seeds in liquid nitrogen for a prolonged period, the treatments PVS1, PVS2, and PVS2PHLO proved to be viable and promising alternatives.

Development of one-axis controlled bearingless motor and its application to a centrifugal pump for extremely low temperature

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1287-1294
Author(s):  
Hirohisa Kato ◽  
Mochimitsu Komori ◽  
Ken-ichi Asami ◽  
Nobuo Sakai
Keyword(s):  
Low Temperature ◽  
Centrifugal Pump ◽  
Liquid Nitrogen ◽  
Flow Rate ◽  
Maximum Flow ◽  
Magnetic Bearing ◽  
Lubricating Oil ◽  
Bearingless Motor ◽  
The Difference ◽  
Conventional Study

In this paper, a centrifugal pump for for extremely low temperature was fabricated and evaluated by experiments in liquid nitrogen. The pump is using a bearingless motor and permanent magnet bearings to levitate and rotate the rotor without lubricating oil. The difference from the conventional study is that a one-axis controlled bearingless motor is used to reduce the magnetic bearing cost and that the bearings are installed in the liquid to eliminate a shaft-seal. Stable levitation and rotation of the rotor were confirmed in the rotation and pump experiments in liquid nitrogen. In pump experiment, the flow rate of liquid nitrogen was measured at 1 cm in a pumping height. The maximum flow rate was 1.3 L/min when the rotation speed is 1,800 rpm.

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