Thermal Properties of Fullerene С56

The behavior of С56 fullerene when heated in a nitrogen atmosphere at a pressure of 105 Pa was studied using computer thermodynamic modeling. The modeling consisted in a complete thermodynamic analysis of the system using the TERRA software package, which is one of the most developed and efficient ones that implements such thermodynamic calculations. Experiment temperature ranges are from 273 to 3373 К. Based on the calculated data, a graph of the carbon balance in the С56-N2 system was constructed, the ongoing physicochemical processes were described, divided into four classes: sublimation, dissociation in the gas phase, chemical reactions occurring in the gas phase, dissociation and chemical reaction in the gas phase. Temperature intervals of reactions are identified. The equilibrium constants of the reactions are calculated and described, as well as the coefficients of these constants are found using the least squares method. The temperature interval of thermal stability of the condensed C56 fullerene and C56 vapors is defined. This work is one of the series of works on the properties of nanoparticles, in the future it is planned to study the thermal properties of higher fullerenes. The data obtained can be used to determine the explosive and fire hazardous properties of fullerenes as a dispersed solid.

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Effect of Machine Smoking Intensity and Filter Ventilation Level on Gas-Phase Temperature Distribution Inside a Burning Cigarette

Beiträge zur Tabakforschung International/Contributions to Tobacco Research ◽

10.1515/cttr-2015-0007 ◽

2015 ◽

Vol 26 (4) ◽

Cited By ~ 2

Author(s):

Bin Li ◽

Lucan Zhao ◽

Chuanfang Yu ◽

Chuan Liu ◽

Yi Jing ◽

...

Keyword(s):

Gas Phase ◽

Medium Temperature ◽

Smoking Intensity ◽

Contour Maps ◽

Distribution Parameters ◽

Temperature Ranges ◽

Phase Temperature ◽

Burning Coal ◽

Complex Temperature ◽

Data Extracting

AbstractAccurate measurements of cigarette coal temperature are essential to understand the thermophysical and thermo-chemical processes in a burning cigarette. The last system-atic studies of cigarette burning temperature measurements were conducted in the mid-1970s. Contemporary cigarettes have evolved in design features and multiple standard machine-smoking regimes have also become available, hence there is a need to re-examine cigarette combustion. In this work, we performed systematic measurements on gas-phase temperature of burning cigarettes using an improved fine thermocouple technique. The effects of machine-smoking parameters (puff volume and puff duration) and filter ventilation levels were studied with high spatial and time resolutions during single puffs. The experimental results were presented in a number of differ-ent ways to highlight the dynamic and complex thermal processes inside a burning coal. A mathematical distribution equation was used to fit the experimental temperature data. Extracting and plotting the distribution parameters against puffing time revealed complex temperature profiles under different coal volume as a function of puffing intensities or filter ventilation levels. By dividing the coal volume prior to puffing into three temperature ranges (low-temperature from 200 to 400 °C, medium-temperature from 400 to 600 °C, and high-temperature volume above 600 °C) by following their development at different smoking regimes, useful mechanistic details were obtained. Finally, direct visualisation of the gas-phase temperature through detailed temperature and temperature gradient contour maps provided further insights into the complex thermo-physics of the burning coal. [Beitr. Tabakforsch. Int. 26 (2014) 191-203]

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Comparative Study of GaN Growth Process by MOVPE

MRS Proceedings ◽

10.1557/proc-572-463 ◽

1999 ◽

Vol 572 ◽

Author(s):

Jingxi Sun ◽

J. M. Redwing ◽

T. F. Kuech

Keyword(s):

High Temperature ◽

Comparative Study ◽

Gas Phase ◽

Residence Time ◽

Gas Flow ◽

Flow Sheet ◽

Flow Zone ◽

High Quality ◽

Phase Temperature ◽

High Temperature Gas

ABSTRACTA comparative study of two different MOVPE reactors used for GaN growth is presented. Computational fluid dynamics (CFD) was used to determine common gas phase and fluid flow behaviors within these reactors. This paper focuses on the common thermal fluid features of these two MOVPE reactors with different geometries and operating pressures that can grow device-quality GaN-based materials. Our study clearly shows that several growth conditions must be achieved in order to grow high quality GaN materials. The high-temperature gas flow zone must be limited to a very thin flow sheet above the susceptor, while the bulk gas phase temperature must be very low to prevent extensive pre-deposition reactions. These conditions lead to higher growth rates and improved material quality. A certain range of gas flow velocity inside the high-temperature gas flow zone is also required in order to minimize the residence time and improve the growth uniformity. These conditions can be achieved by the use of either a novel reactor structure such as a two-flow approach or by specific flow conditions. The quantitative ranges of flow velocities, gas phase temperature, and residence time required in these reactors to achieve high quality material and uniform growth are given.

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Rapid compressions in a captive bubble apparatus are isothermal

Journal of Applied Physiology ◽

10.1152/japplphysiol.00591.2003 ◽

2003 ◽

Vol 95 (5) ◽

pp. 1896-1900

Author(s):

Wenfei Yan ◽

Stephen B. Hall

Keyword(s):

Hydrostatic Pressure ◽

Gas Phase ◽

Pulmonary Surfactant ◽

First Order ◽

First Order Kinetics ◽

Gas Phase Molecules ◽

Actual Change ◽

Phase Temperature ◽

Two Phases ◽

Interfacial Films

Captive bubbles are commonly used to determine how interfacial films of pulmonary surfactant respond to changes in surface area, achieved by varying hydrostatic pressure. Although assumed to be isothermal, the gas phase temperature (Tg) would increase by >100°C during compression from 1 to 3 atm if the process were adiabatic. To determine the actual change in temperature, we monitored pressure (P) and volume (V) during compressions lasting <1 s for bubbles with and without interfacial films and used P · V to evaluate Tg. P · V fell during and after the rapid compressions, consistent with reductions in n, the moles of gas phase molecules, because of increasing solubility in the subphase at higher P. As expected for a process with first-order kinetics, during 1 h after the rapid compression P · V decreased along a simple exponential curve. The temporal variation of n moles of gas was determined from P · V >10 min after the compression when the two phases should be isothermal. Back extrapolation of n then allowed calculation of Tg from P · V immediately after the compression. Our results indicate that for bubbles with or without interfacial films compressed to >3 atm within 1 s, the change in Tg is <2°C.

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The major toxin from the Australian Common Brown Snake is a hexamer with unusual gas-phase dissociation properties

Proteins Structure Function and Bioinformatics ◽

10.1002/prot.22259 ◽

2009 ◽

Vol 75 (2) ◽

pp. 478-485 ◽

Cited By ~ 23

Author(s):

J. Andrew Aquilina

Keyword(s):

Gas Phase ◽

Gas Phase Dissociation

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Hydrogen Production via the Iron/Iron Oxide Looping Cycle

ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C ◽

10.1115/es2011-54499 ◽

2011 ◽

Cited By ~ 4

Author(s):

A. Singh ◽

F. Al-Raqom ◽

J. Klausner ◽

J. Petrasch

Keyword(s):

Iron Oxide ◽

Hydrogen Production ◽

Gas Phase ◽

Energy Content ◽

Operation Conditions ◽

Iron Oxide Reduction ◽

Temperature Ranges ◽

Iron Iron ◽

Gas Phase Separation ◽

Distinct Temperature

The iron/iron-oxide looping cycle has the potential to produce high purity hydrogen from coal or natural gas without the need for gas phase separation: Hydrogen is produced from steam oxidation of iron or Wustite yielding primarily Magnetite; Magnetite is then reduced back to iron/Wustite using syngas (CO+H2). A system model has been developed to identify favorable operation conditions and process configurations. Process configurations for three distinct temperature ranges, (i) 500–950 K, (ii) 950–1100 K, and (iii) 1100–1200 K have been developed. The energy content of high temperature syngas from conventional coal gasifiers is sufficient to drive the looping process throughout the temperature range considered. Temperatures around 1000 K are advantageous for both the hydrogen production step and the iron oxide reduction step. Simulations of a large number of subsequent cycles indicate that quasi-steady operation is reached after approximately 5 cycles. Comparison of simulations and experiments indicate that the process is currently limited by chemical kinetics at lower temperatures. Therefore, product recirculation should be used for a scaled-up process to increase reactant residence times while maintaining sufficient fluidization velocity.

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Effects of Glycerol on the Thermal Properties of Phosphate Buffered Saline and Porcine Liver at Subzero Temperatures

ASME 2007 Summer Bioengineering Conference ◽

10.1115/sbc2007-176561 ◽

2007 ◽

Author(s):

Jeung H. Choi ◽

John C. Bischof

Keyword(s):

Phase Transition ◽

Thermal Properties ◽

Property Values ◽

Insufficient Data ◽

Porcine Liver ◽

Water Ice ◽

Subzero Temperatures ◽

Temperature Ranges ◽

Phase Change Phenomena ◽

Phosphate Buffered Saline

Improvements in the prediction of thermal behavior during cryosurgery and cryopreservation can help improve the outcome of these cryobiological applications. The accuracy of the models depends on numerous factors including the kinetics and energy release during phase change phenomena and knowledge of thermal properties. Furthermore, connecting the thermal properties to crystalline, amorphous, and other phases adds an important mechanistic dimension that can also improve and direct an outcome. However, insufficient data for thermal properties in the subzero domain result in reliance on property estimations based usually upon tabulated water-ice data or weight averaged values from known materials primarily in temperature ranges above −40 °C [1]. This study focused on expanding the thermal properties database for both solutions and tissues. Results for Phosphate Buffered Saline (PBS) and porcine liver with glycerol at subzero temperatures (−150 ∼ 0 °C) are reported. The shifting of thermal property values due to sample crystallization, amorphous phase transition, and melting is discussed.

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