Study on Thermal Isomerization of Isopimaric Acid

The thermal isomerization reaction of isopimaric acid was studied by a treatment at different temperature of 250 °C, 260 °C and 270 °C for 1-5 h under the protection of nitrogen. The isomerization mechanism of isopimaric acid was illuminated. Isopimaric acid was remarkably isomerized to 8, 15-isopimaric acid and sandaracopimaric acid, the higher thermal treatment temperature combined with longer thermal treatment time, the faster isomerization rate of isopimaric acid was observed. It was found that the isomerization rate of isopimaric acid towards 8, 15-isopimaric acid was faster than to sandaracopimaric acid. The decomposition reaction of pimaric-type acids occurred slightly in conditions of 250 ~ 270 °C.

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The Influence of SiC Powder Source on 6H-SiC Single Crystals Grown by the Sublimation Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.527-529.91 ◽

2006 ◽

Vol 527-529 ◽

pp. 91-94 ◽

Cited By ~ 1

Author(s):

Jae Woo Kim ◽

Soo Hyung Seo ◽

Kwan Mo Kim ◽

Joon Suk Song ◽

Tae Sung Kim ◽

...

Keyword(s):

Thermal Treatment ◽

High Purity ◽

Doping Concentration ◽

Growth Stage ◽

Treatment Time ◽

Alpha Phase ◽

Treatment Temperature ◽

Initial Growth ◽

Thermal Treatment Temperature ◽

Sublimation Method

We examined the influence of thermal treatment of high-purity SiC powder on 6H-SiC crystal growth. The doping concentration was decreased by increasing either thermal treatment temperature or time. It was also found that the defects such as micropipes and planar cavities were generated under relatively long treatment time (13 hours), because SiC powders were significantly graphitized. A 6H-SiC crystal grown by using SiC source treated at 2100oC for 6 hours revealed the best result with relatively low micropipes. For the effects of thermal treated sources on the improvement of crystallinity, it could be explained that both the amount of alpha phase transformed from high-purity beta-SiC powder and the elimination of porous powders in SiC powder had an influence on the removal of silicon droplets, resulting in higher Si vapor pressure at the initial growth stage.

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Zeolite Synthesis Using Sewage Sludge by Molten-Salt Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.569.329 ◽

2008 ◽

Vol 569 ◽

pp. 329-332

Author(s):

Yeong Seok Yoo ◽

Kyeong Ho Cheon ◽

Jae Ik Lee ◽

Beom Suk Kim ◽

Woo Seob Shin ◽

...

Keyword(s):

Sewage Sludge ◽

Thermal Treatment ◽

Molten Salt ◽

Sodium Hydroxide ◽

Treatment Time ◽

Treatment Temperature ◽

Zeolite Synthesis ◽

Molten Salt Method ◽

Synthesis Time ◽

Zeolitic Materials

This study was conducted to synthesize zeolitic materials using sewage sludge by molten-salt method the effective method was investigate to reduce the thermal treatment time by adding zeolite seed and excessive sodium hydroxide. To synthesis zeolitic materials, sewage sludge was used as Si and Al sources, also Na2SO4 and NaOH were added as stabilizer and mineralizer respectively. Sewage sludge was prepared by calcination at 550°C/3hr to remove organic materials. As a result of thermal treatment at 950°C for 6~24hrs, more than 18 hours was required to synthesize zeolitic materials without adding zeolite seed. On the other hand, it is observed that hydroxyl-sodalite was synthesized in 9 hours thermal treatment and Na-P1 also in 12 hours when zeolite seed was added, but no other differences were observed when excessive sodium hydroxide was added. Consequently, the overall reaction time required could be reduced by adding zeolite seed and changing thermal treatment temperature. However, addition of NaOH does not show significant effect on the reduction of zeolite synthesis time.

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A Kinetic Study of the Thermal Isomerization of and Related Complexes

Canadian Journal of Chemistry ◽

10.1139/v75-245 ◽

1975 ◽

Vol 53 (12) ◽

pp. 1735-1738 ◽

Cited By ~ 6

Author(s):

William R. Cullen ◽

Frank L. Hou

Keyword(s):

Kinetic Study ◽

Thermal Isomerization ◽

Isomerization Reaction ◽

Kinetics Of

The kinetics of the unimolecular isomerization reaction[Formula: see text]have been studied. The ΔH≠ values in kcal mol−1 are 36.8 ± 2.0 (M = M′ = Mn ), 46.8 ± 0.5 (M = M′ = Re ), 39.2 ± 2.8 (M = Mn, M′ = Re ). The mechanism of the rearrangement is discussed.

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An Analytical Evaluation of the Optimal Thermal Dose Delivery Parameters for Thermal Therapies

Heat Transfer: Volume 2 ◽

10.1115/ht2003-47361 ◽

2003 ◽

Cited By ~ 1

Author(s):

Kung-Shan Cheng ◽

Robert B. Roemer

Keyword(s):

Blood Flow ◽

Treatment Time ◽

Heating Time ◽

Treatment Temperature ◽

Thermal Dose ◽

Dose Delivery ◽

Thermal Therapies ◽

Initial Power ◽

High Treatment ◽

Optimal Heating

This study derives the first analytic solution for evaluating the optimal treatment parameters needed for delivering a desired thermal dose during thermal therapies consisting of a single heating pulse. Each treatment is divided into four time periods (two power-on and two power-off), and the thermal dose delivered during each of those periods is evaluated using the non-linear Sapareto and Dewey equation relating thermal dose to temperature and time. The results reveal that the thermal dose delivered during the second power-on period when T>43C (TD2) and the initial power-off period when T>43C (TD3) contribute the major portions of the total thermal dose needed for a successful treatment (taken as 240 CEM43°C), and that TD3 dominates for treatments with higher peak temperatures. For a fixed perfusion value, the analytical results show that once the maximum treatment temperature and the total thermal dose (e.g., 240 CEM43°C) are specified, then the required heating time and the applied power magnitude are uniquely determined. These are the optimal heating parameters since lower/higher values result in under-dosing/over-dosing of the treated region. It is also shown that higher maximum treatment temperatures result in shorter treatment times, and for each patient blood flow there is a maximum allowable temperature that can be used to reach the desired thermal dose. In addition, since TD2 and TD3 contribute most of the total thermal dose, and they are both significantly affected by the blood flow present for high treatment temperatures, these results show that perfusion effects must be considered when attempting to optimize high temperature thermal therapy treatments (no excess thermal dose delivered, minimum power applied and shortest treatment time attained).

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Optimization of Treatment Parameters on the Recycling of Used Lubricating Oil

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.699.735 ◽

2013 ◽

Vol 699 ◽

pp. 735-741 ◽

Cited By ~ 1

Author(s):

Ambali Saka Abdulkareem ◽

Edison Muzenda ◽

Ayo Samuel Afolabi

Keyword(s):

Metal Content ◽

Acid Treatment ◽

Conventional Treatment ◽

Treatment Time ◽

Optimal Solution ◽

Absorption Spectrometry ◽

Treatment Temperature ◽

Lubricating Oil ◽

Used Oil ◽

Treatment Parameter

Acid treatment is one of the cheapest techniques and least applicable processes in the recycling of used lubricating oils. In this work, the performance of sulphuric acid in the treatment used oil was studied. The effects of the critical treatment parameters (acid volume, concentration of the acid, treatment temperature, stirring time and treatment time) were investigated by varying one treatment parameter at a time and analysing metal content in the sample of the treated oil using atomic absorption spectrometry (ASS). Thereafter, an optimal solution was determined by the combination of the optimum values of each treatment parameters. The original conventional treatment parameter values, resulted in 13.2 ppm and thereafter was optimised to 11 ppm this showed a definite improvement in efficiency. This result is also comparable to other data obtained in previously studied work which employed the same conventional treatment parameters. The optimal solution is within 10% variation as compared the standard individual metal content which ranges 0-10 ppm.

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A Study on The Phase Transformation and Exchange-Coupling of (Nd0 95La0 05)9 5FebalCo5Nb2B10.5 Nanocomposites

MRS Proceedings ◽

10.1557/proc-577-209 ◽

1999 ◽

Vol 577 ◽

Author(s):

Q. Chen ◽

B. M. Ma ◽

B. Lu ◽

M. Q. Huang ◽

D. E. Laughlin

Keyword(s):

Grain Size ◽

Magnetic Properties ◽

Phase Transformation ◽

Thermal Treatment ◽

Grain Growth ◽

Exchange Coupling ◽

Phase Distribution ◽

Maximum Energy ◽

Treatment Temperature ◽

Phase Identification

ABSTRACTThe phase transformation and the exchange coupling in (Ndo095Lao005)9.5FebaICOsNb 2BI05 have been investigated. Nanocomposites were obtained by treating amorphous precursors at temperatures ranging from 650TC to 9500C for 10 minutes. The magnetic properties were characterized via the vibrating sample magnetometer (VSM). X-ray diffraction (XRD), thermomagnetic analysis (TMA), and transmission electron microscopy (TEM) were used to perform phase identification, measure grain size, and analyze phase distribution. The strength of the exchange coupling between the magnetically hard and soft phases in the corresponding nanocomposite was analyzed via the AM-versus-H plot. It was found that the remanence (Br), coercivity (Hci), and maximum energy product (BHmax) obtained were affected by the magnetic phases present as well as the grain size of constituent phases and their distribution. The optimal magnetic performance, BHm, occurred between 700°C to 750°C, where the crystallization has completed without excessive grain growth. TMA and TEM indicated that the system was composed of three phases at this point, Nd2(Fe Co) 14B, ca-Fe, and Fe3B. The exchange coupling interaction among these phases was consistently described via the AM-versus-H plot up to 750°C. The Br, Hci, and BHmax degraded severely when the thermal treatment temperature increased from 750°C. This degradation may be attributed to the grain growth of the main phases, from 45 to 68nm, and the development of precipitates, which grew from 5nm at 750°C to 12nm at 850°C. Moreover, the amount of the precipitates was found to increase with the thermal treatment temperatures. The precipitates, presumably borides, may cause a decrease in the amount of the a-Fe and Fe 3B and result in a redistribution of the Co in the nanocomposites. The increase of the Co content in the Nd 2(Fe Co) 14B may explain the increase of its Curie temperature with the thermal treatment temperatures. In this paper, we examine the impacts of these factors on the magnetic properties of (Ndo 95Lao 05)9 5FebaICosNb2B10.5 nanocomposite.

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