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Treatment Temperature (treatment + temperature)
Selected AbstractsImpact of Kerogen Heterogeneity on Sorption of Organic Pollutants.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2009Abstract The overall goal of the present study was to establish correlations between organic pollutant sorption and physicochemical properties of kerogen materials. Three coal samples, each representing a typical kerogen type, were used as the starting materials. A thermal technique was employed to treat the kerogen materials under seven different temperatures ranging from 200 to 500C to simulate different diagenetic history. These samples were systematically characterized for their chemical compositions, functionalities, physical rigidity, and optical properties. The results showed that the chemical, spectroscopic, and optical microscopic properties of each kerogen series changed consistently as a function of treatment temperature or kerogen maturation. The oxygen-to-carbon atomic ratio decreased from 0.29, 0.12, and 0.07 for the original lignite (XF0), fusinite (HZ0), and lopinite (LP0) samples, respectively, to 0.07, 0.06, and 0.04 for XF7, HZ7, and LP7, respectively, that underwent the highest temperature treatment. The hydrogen-to-carbon atomic ratio exhibited similar reducing trend, which is consistent with the aromaticity increasing from 45 to 58% of the original samples to 76 to 81% of highly mature samples. Under the fluorescence microscope, the organic matrix changed from yellow (original lignite sample) and red-brown (original lopinite sample) to colorless for the samples of higher maturation. The measured reflecting index increased from the original samples to the highly mature samples. Moreover, the original and the slightly matured samples exhibited very different chemical compositions and structural units among the three types due to the difference in their source materials. As the kerogen maturation increased, such differences decreased, indicating highly mature kerogen became homogenized regardless of the source material. [source] Crystallization effects on autoclave foaming of polycarbonate using supercritical carbon dioxideADVANCES IN POLYMER TECHNOLOGY, Issue 4 2006L. Mascia Abstract In this study, the conditions leading to the formation of cells and to the onset of crystallization of polycarbonate were examined with the use of supercritical carbon dioxide for the production of foams from preforms. Small plaques cut from extruded sheets were treated with supercritical carbon dioxide in an autoclave at temperatures varying from 60 to 200°C and from 4.5 to 30 MPa pressure. Visual observations and stereoscan electron microscopy examination revealed that penetration of supercritical carbon dioxide takes place via the advancing layer mechanism and that, for the particular grade of polycarbonate used in this study, the nucleation of the cells can take place at temperatures as low as 60°C. It requires, however, long treatment times and high pressures, and the growth of foam cells is severely restricted. Nucleation and growth of cells occurred much more readily at somewhat higher temperatures. With treatments at around 80°C, the onset of crystallization started to impose considerable hindrance to the formation of uniform and evenly distributed cells. This becomes increasingly evident at higher temperatures, between 100 and 180°C, owing to the formation of large spherulitic crystalline domains. A very effective nucleation and growth mechanism for the formation of cells was obtained, on the other hand, with treatments at 200°C due to the absence of crystallization phenomena. The degree of crystallinity increased with increasing treatment temperature, and the resulting morphology gave rise to two broad melting peaks. These are displaced to higher temperatures and become closer, merging into one peak with a low-temperature shoulder. These events were monitored by thermal analysis and wide-angle X-ray diffraction examinations. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 25:225,235, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20075 [source] Inactivation of Bacillus spores in reconstituted skim milk by combined high pressure and heat treatmentJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2006K.J. Scurrah Abstract Aims:, To determine the resistance of a variety of Bacillus species spores to a combined high pressure and heat treatment; and to determine the affect of varying sporulation and treatment conditions on the level of inactivation achieved. Methods and Results:, Spores from eight Bacillus species (40 isolates) were high pressure,heat treated at 600 MPa, 1 min, initial temperature 72°C. The level of inactivation was broad (no inactivation to 6 log10 spores ml,1 reduction) and it varied within species. Different sporulation agar, high pressure equipment and pressure-transmitting fluid significantly affected the response of some isolates. Varying the initial treatment temperature (75, 85 or 95°C) shifted the relative order of isolate high pressure,heat resistance. Conclusions:, The response of Bacillus spores to combined high pressure,heat treatment is variable and can be attributed to both intrinsic and extrinsic factors. The combined process resulted in a high level of spore inactivation for several Bacillus species and is a potential alternative treatment to traditional heat-only processes. Significance and Impact of the Study:, Sporulation conditions, processing conditions and treatment temperature all affect the response of Bacillus spores to the combined treatment of high pressure and heat. High levels of spore inactivation can be achieved but the response is variable both within and between species. [source] Inactivation of Escherichia coli O157:H7 and Salmonella enteritidis in Liquid Egg White Using Pulsed Electric FieldJOURNAL OF FOOD SCIENCE, Issue 3 2006Malek Amiali ABSTRACT: The effects of temperature and pulsed electric field (PEF) intensity on inactivation of pathogens such as Escherichia coli O157:H7 and Salmonella enteritidis in egg white was investigated. Liquid egg white inoculated with 108 colony-forming units (CFU)/mL of each pathogen was treated with up to 60 pulses (each of 2 JAS width) at electric field intensities of 20 and 30 kV/cm. The processing temperatures were 10°C, 20°C, and 30°C. After treatment, uninjured and total viable cells were enumerated in selective and nonselective agars, respectively. Maximum inactivations of 3.7 and 2.9 log units were obtained for S. enteritidis and E. coli O157:H7, respectively, while injured cells accounted for 0.5 and 0.9 logs for E. coli O157:H7 and S. enteritidis, respectively. For both bacteria, increasing treatment temperature tended to increase the inactivation rate. There was synergy between electric field intensity and processing temperature. The inactivation rate constant kT values for E. coli O157:H7 on both selective and nonselective agars were 8.2 × 10 -3 and 6.6 × 10 -3/,S, whereas the values for S. enteritidis were 16.2 × 10 -3 and 12.6 × 10 -3/,S, respectively. The results suggest that E. coli O157:H7 was more resistant to heat-PEF treatment compared with S. enteritidis. [source] Raman spectroscopic evaluation of polyacrylonitrile-based carbon nanofibers prepared by electrospinningJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2004Chan Kim Abstract Poly(acrylonitrile) (PAN) solutions in N,N -dimethylformamide were electrospun into webs consisting of 350 nm ultra-fine fibers. The webs were oxidatively stabilized and followed by heat treatment in the range of 700,1000°C. Characterization of the microstructure of PAN-based carbon nanofibers was performed by x-ray diffraction, field-emission scanning electron microscopy, electrical conductivity and Raman spectroscopy. The Lc(002) and La(10) values were calculated to be 1.85,2.15 and 2.23,3.36 nm, respectively. The Lc(002) and La(10) values increased by about 86% and 66%, respectively, when the heat treatment temperature (HTT) was increased from 700 to 1000°C. The electrical conductivity of carbonized PAN nanofiber webs increased with increasing carbonization temperature, being 6.8 × 10,3 and 1.96 S cm,1 at 700 and 1000°C, respectively. The D and G bands from Raman scattering were fitted into a Gaussian,Lorentzian hybridized function, and the crystallite sizes in the nanofibers were evaluated from the R -values determined from the ratios of the intensity of the G band to that of the D band. The domain size of the graphitic layers was in the range 1.6,3.2 nm with higher values at higher HTT. Copyright © 2004 John Wiley & Sons, Ltd. [source] A Simple Oxidation Route to Prepare Pseudobrookite from Panzhihua Raw IlmeniteJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Xi Chen A simple oxidation route to prepare pseudobrookite from Panzhihua raw ilmenite was developed. By oxidizing ilmenite concentrate in air for 3 h at 1473 K, a pure pseudobrookite was achieved. The X-ray diffraction studies showed a possible sequence of the phase evolution with temperature, FeTiO3,FeTiO3+Fe2O3+TiO2,Fe2O3+TiO2+Fe2Ti3O9,Fe2O3+TiO2+Fe2TiO5,Fe2TiO5. The sluggish formation reaction of the target product was ascribed to the low heat treatment temperature. During the phase transformation, the extra Ti atoms from FeTiO3 accommodate into the 4c and 8f sites to form the solid solution (Fe,Ti)2TiO5. AC susceptibility determinations indicated that the as-prepared pseudobrookite was an antiferromagnetic compound and performed the typical anisotropic spin glass behaviors. The decreased phase transition temperature of the prepared pseudobrookite from order to disorder meant a high disorder degree. This oxidation route might be useful to the comprehensive utilization of raw ilmenite, especially for Panzhihua ilmenite in Pan-Xi region of China. [source] Controlling the Size and Morphology of TiO2 Powder by Molten and Solid Salt SynthesisJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2008Banasri Roy Nano and submicrometer scale titanium oxide (TiO2) powders were synthesized by solid and molten salt synthesis (SSS and MSS) from amorphous titanium hydroxide precipitate. Sodium chloride (NaCl) and dibasic sodium phosphate (Na2HPO4·2H2O, DSP) separately or as mixture with different weight ratios were used as the salts. At the eutectic salt composition (20% DSP/80% NaCl), the microstructure and phase composition of the TiO2 was changed from equiaxed nanoparticles of anatase with size ,40,50 nm, to mixed microstructure of bundle and acicular particles of rutile with 0.05,0.2 ,m diameter, 6,10 ,m length, and aspect ratio 20,60 depending on treatment time and temperature. At high temperature (825°C) and long time (30 h), microstructural differences were significant for the powders treated with different salts. Particle morphologies ranged from equiaxed, to acicular, to bundles, to nanofibers with very high aspect ratio. At lower treatment temperature (725°C) for shorter time (3 h), the morphology of the products did not change with different salt compositions, but the crystallite sizes changed appreciably. Different starting titanium precursors influenced particle size at lower temperature and time. Titanium hydroxide heat treated without salt resulted in significant grain growth and fused secondary particles, as compared with more finely separated and lightly agglomerated powders resulting from SSS and MSS treatments. [source] Application of the Weibull model to describe inactivation of Listeria monocytogenes and Escherichia coli by citric and lactic acid at different temperaturesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2006R Virto Abstract Inactivation of Listeria monocytogenes and Escherichia coli by citric (10-150 g L,1) and lactic (1-60 mL L,1) acids at different temperatures (4, 20, 40 °C) has been investigated. Bactericidal effect of both acids was dependent on time and temperature of exposure and acid concentration. Survival curves of L. monocytogenes treated by lactic acid were concave downward and those treated by citric acid were linear. On the other hand, survival curves of E. coli treated by both organic acids were concave upward. Shape of survival curves depended on the type of acid but not on the treatment temperature. A mathematical model based on the Weibull distribution accurately described the kinetics of inactivation of both microorganisms by both acids. This model allowed quantification and comparison of the acid resistance of L. monocytogenes and E. coli. Lactic acid was more effective than citric acid and E. coli was more sensitive to both acids than L. monocytogenes. Copyright © 2006 Society of Chemical Industry [source] Near-infrared photo-excited emission from tissues treated at different temperature levelsLASERS IN SURGERY AND MEDICINE, Issue 1 2001Jing Tang MD Abstract Background and Objective There is a lack of methods to evaluate the extent of thermal treatment of biological tissue. The intensity of the near-infrared (NIR) emission photo-excitation was investigated from tissue undergoing different levels of heat treatment. Study Design/Materials and Methods Chicken muscle was heated in an oven at different temperature levels ranging from 40°C until burn-off. The spectral emission intensity from these heat-treated tissues was measured with a CCD camera and the intensity was calculated. Results The emission intensity increased proportionally with respect to the extent of treatment temperature until burning. Linear relationships between treatment temperature and the emission intensity from tissue samples were found in three temperature ranges: from 40 to 160°C, from 165 to 220°C, and from 225 to 250°C. Conclusions The change in tissue damage after heat treatment could be detected by measuring the NIR emission intensity from the thermally damaged tissues. Lasers Surg. Med. 29:18,22, 2001. © 2001 Wiley-Liss, Inc. [source] Spin-dependent-magnetoresistance control by regulation of heat treatment temperature for magnetite nano-particle sinterANNALEN DER PHYSIK, Issue 12 2009H. Kobori Abstract The control of spin-dependent-magnetoresistance by regulation of the heat treatment (HT) temperature for magnetite (Fe3O3) nano-particle sinter (MNPS) has been studied. The average nano-particle size in the MNPS is 30nm and the HT was carried out from 400°C to 800°C. The HT of the MNPS varies the coupling form between adjacent magnetite nano-particles and the crystallinity of that. The measurements on electrical resistance (ER), magnetoresistance (MR) and magnetization were performed between 4K and 300K. The behavior of the ER and MR considerably changes at the HT temperature of ,600°C. Below ,600°C the ER indicates the variable-range-hopping conduction behavior and the MR shows the large intensity in a wide temperature region. Above ,600°C the ER shows the indication of the Verwey transition near 110K like a bulk single crystal and the MR designates the smaller intensity. We consider that below ,600°C the ER and MR are dominated by the grain-boundary conduction and above ,600°C those are determined by the inter-grain conduction. The magnetic field application to the grain-boundary region is inferred to cause the large enhancement of the MR. [source] Surface Devitrification and the Growth of Cristobalite in Borofloat® (Borosilicate 8330) GlassJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010Berker Mo, ulkoç Borofloat® (borosilicate 8330) glass is an important type of inorganic glass, both scientifically and commercially. During prolonged heat treatment of this glass above its glass transition temperature of 525°C, heterogeneous nucleation, and growth of cristobalite crystals occur. The kinetics and morphology of this crystal growth have been studied for heat treatment temperatures at and above 660°C. The activation energy for crystal growth is estimated to be 185±10 kJ/mol. This is attributed to the diffusion of boron, rather than sodium, being the rate-limiting step within the borosilicate framework. Contact with the atmosphere is shown to initiate the nucleation of cristobalite crystals, while deposition of a thin silicon nitride surface coating on the glass helps to prevent this nucleation. [source] Hyperthermic injury to adipocyte cells by selective heating of subcutaneous fat with a novel radiofrequency device: Feasibility studiesLASERS IN SURGERY AND MEDICINE, Issue 5 2010Walfre Franco PhD Abstract Background and Objective The main objective of the present study is to demonstrate the feasibility of utilizing a novel non-invasive radiofrequency (RF) device to induce lethal thermal damage to subcutaneous adipose tissue only by establishing a controlled electric field that heats up fat preferentially. Study Design/Materials and Methods Adipocyte cells in six-well plates were subjected to hyperthermic conditions: 45, 50, 55, 60, and 65°C during 1, 2, and 3,minutes. Cell viability was assessed 72,hours after exposure. Two groups of abdominoplasty patients were treated with the RF device during and days before their surgical procedure. Temperatures of cutaneous and subcutaneous tissues were measured during treatment (3,minutes) of the first group. The immediate tissue response to heating was assessed by acute histology. The delayed tissue response was assessed by histology analysis of the second group, 4, 9, 10, 17, and 24 days after treatment (22,minutes). A mathematical model was used to estimate treatment temperatures of the second group. The model uses patient-based diagnostic measurements as input and was validated with in vivo clinical temperature measurements. Results Cell viability dropped from 89% to 20% when temperature increased from 45 to 50°C during 1,minute exposures. Three minutes at 45°C resulted in 40% viability. In vivo, the temperature of adipose tissue at 7,12,mm depth from the surface increased to 50°C while the temperature of cutaneous tissues was <30°C during RF exposure. Acute and longitudinal histology evaluations show normal epidermal and dermal layers. Subcutaneous tissues were also normal acutely. Subcutaneous vascular alterations, starting at day 4, and fat necrosis, starting at day 9, were consistently observed within 4.5,19,mm depth from the skin surface. Subcutaneous tissue temperatures were estimated to be 43,45°C for 15,minutes. Conclusions A controlled internal electric field perpendicular to the skin,fat interface is selective in heating up fat and, consequently, has the ability to induce lethal thermal damage to subcutaneous adipose tissues while sparing overlying and underlying tissues. In vitro adipocyte cells are heat sensitive to thermal exposures of 50 and 45°C on the order of minutes, 1 and 3,minutes, respectively. In vivo, 15,minutes thermal exposures to 43,45°C result in a delayed adipocyte cellular death response,in this study, 9 days. The novel RF device presented herein effectively delivers therapeutic thermal exposures to subcutaneous adipose tissues while protecting epidermal and dermal layers. Lasers Surg. Med. 42:361,370, 2010. © 2010 Wiley,Liss, Inc. 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