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1.
Multigram quantities (2.5-10 g) of highly purified IgG were obtained within 4 h from serum by using Avid AL packed in a radial-flow column. Avid AL is an affinity gel containing a synthetic, low-mol-wt ligand capable of selectively binding IgG from serum of all animal species tested. By packing the gel in a radial-flow column up to 500 mL, a high flow rate of 50 mL/min can be achieved without adversely affecting the performance of the gel and the purity of the isolated antibody. 相似文献
2.
Joseph M. Augl 《Journal of polymer science. Part A, Polymer chemistry》1972,10(12):3651-3663
Three samples of poly{2,2′-[N,N′-bis(1,4-phenylene)benzophenone-3,3′,4,4′-tetracarboxylimide-6,6′-bis(3-phenyl-quinoxaline)]} (PPIQ), were prepared, differing in molecular weights and polymer chain endings. Their thermal degradation in vacuo and in air was determined by isothermal weight loss measurements. As in the case of poly-[2,2′-(1,4-phenylene)-6,6′-bis(3-phenylquinoxaline)] (PPQ), the temperature coefficients of thermal degradation in air were independent of molecular weight. However, in contrast, the temperature coefficients were independent of the type of polymer endgroups. It is, therefore, concluded that, contrary to amino-terminated PPQ's, polymer chain-end unzipping of PPIQ is of minor importance during thermal-oxidative degradation. 相似文献
3.
Characterization of rice husks and the products of its thermal degradation in air or nitrogen atmosphere 总被引:2,自引:0,他引:2
S. D. Genieva S. Ch. Turmanova A. S. Dimitrova L. T. Vlaev 《Journal of Thermal Analysis and Calorimetry》2008,93(2):387-396
Rice husk is a by-product of rice milling process and are a major waste product of the agricultural industry. They have now
become a great source as a raw biomass material for manufacturing value-added silicon composite products, including silicon
carbide, silicon nitride, silicon tetrachloride, pure silicon, zeolite, fillers of rubber and plastic composites, adsorbent
and support of catalysts. The bulk and true densities of raw rice husk with different moisture and sizes were determined.
The rice husk was subjected to pyrolysis in fluidized-bed reactor in air or nitrogen atmosphere.
The products obtained were characterized by thermogravimetric and X-ray powder analysis, IR-spectroscopy, scanning electron
microscopy and nitrogen adsorption at 77 K. The specific surface area of the products is comparable with this of γ-Al2O3. The kinetics of H2SeO3 adsorption out of aqueous solutions at 298 K was studied. The adsorption capacity of white rice husks ash was found to be
higher than that of black rice husk ash and the adsorption kinetics obeyed the second order kinetic equation. 相似文献
4.
The thermal decomposition reactions of CH3CH2C(CH3)2COOAg (1), (CH3)3SiCH2COOAg (2), CF3COOAg (3), (CH3)3CCOOAg (4), C2H5COOAg (5), C3F7COOAg (6), C6F13COOAg (7) and (CF2)3(COOAg)2 (8) were studied in N2 atmosphere using thermogravimetry (TG), derivative thermogravimetry and differential thermal analysis. Characterized compounds decomposed in one- or multi-step processes with metallic silver formation in the range 215–465 °C. TG-IR studies of gases evolved during thermolysis revealed products of decomposition, such as carboxylic acids, CO2 and recombination reactions. 相似文献
5.
Busch C Streibel T Liu C McAdam KG Zimmermann R 《Analytical and bioanalytical chemistry》2012,403(2):419-430
A coupling between a cigarette smoking simulator and a time-of-flight mass spectrometer was constructed to allow investigation
of tobacco smoke formation under simulated burning conditions. The cigarette smoking simulator is designed to burn a sample
in close approximation to the conditions experienced by a lit cigarette. The apparatus also permits conditions outside those
of normal cigarette burning to be investigated for mechanistic understanding purposes. It allows control of parameters such
as smouldering and puff temperatures, as well as combustion rate and puffing volume. In this study, the system enabled examination
of the effects of “smoking” a cigarette under a nitrogen atmosphere. Time-of-flight mass spectrometry combined with a soft
ionisation technique is expedient to analyse complex mixtures such as tobacco smoke with a high time resolution. The objective
of the study was to separate pyrolysis from combustion processes to reveal the formation mechanism of several selected toxicants.
A purposely designed adapter, with no measurable dead volume or memory effects, enables the analysis of pyrolysis and combustion
gases from tobacco and tobacco products (e.g. 3R4F reference cigarette) with minimum aging. The combined system demonstrates
clear distinctions between smoke composition found under air and nitrogen smoking atmospheres based on the corresponding mass
spectra and visualisations using principal component analysis. 相似文献
6.
Thermal degradation of wood treated with guanidine compounds in air: Flammability study 总被引:1,自引:0,他引:1
Wood has been treated with guanidine phosphate, guanidine nitrate, guanidine carbonate and guanidine chloride to impart flame retardancy. The samples were subjected to differential thermal analysis (DTA) and thermogravimetry (TG) from ambient temperature to 800°C in air to study their thermal behaviors. From the resulting data, kinetic parameters for different stages of thermal degradation were obtained following the method of Broido. For the decomposition of wood and flame retardant wood, the activation energy was found to decrease from 116 to 54 kJ mol–1; the char yield was found to increase from 5.6 to 34.9%, LOI from 18 to 41.5, which indicated that the flame retardancy of treated wood was improved. Effects of the different compounds on the degradation and flammability of wood have also been proposed.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
7.
In this study, thermal degradation and their related kinetics have been investigated mainly by means of thermal gravimetrical analyzer (TGA) under the dynamic nitrogen and air atmospheres for the chemically prepared biodegradable aliphatic-aromatic copolyesters of poly(butylene succinate-co-butylene terephthalate) (PBST). To further shed new lights on the comonomer molar composition and experimental condition dependences of thermal degradation kinetics, the as-known Friedman model was at first applied to quantitatively evaluate the kinetic parameters in terms of activation energy (E), degradation reaction order (n) and the frequency factor (Z). The results clearly demonstrated that thermal stabilities of these PBST copolyesters were substantially enhanced with the incorporation of more rigid butylene terephthalate comonomer, and tended to be much better in nitrogen than in air. Furthermore, the Friedman, Freeman-Carroll and Chang models were concurrently employed to quantitatively evaluate the thermal degradation kinetic parameters of the PBST copolyesters in nitrogen at different heating rates of 1, 2 and 5 K/min. It was found that the thermal degradation kinetic parameters for the PBST copolyesters were strongly dependent on the heating rate and calculating models. In addition, life-time parameters of the biodegradable PBST copolyesters were first calculated to predict the maximum usable temperatures, and this would be useful for practical application of these new bio-based green plastics. 相似文献
8.
The thermal degradation of four different forms of cellulose in nitrogen has been studied by using a thermobalance. In TG experiments a total weight loss at 900°C was 80% in the cases of film and pulp samples and 83% for two powder forms. The results for the isothermal degradation of the four samples at 270°C are plotted as degree of degradation α against reduced time t/t0.5 and compared with the master plots of Sharp, Brindley, and Achar. The experimental data fit most closely the plot for the Avrami-Erofeev equation in the form kt = {–ln (1–α)}1/n where n = 2. An activation energy of 144 kJ/mole has been found for the degradation of one of the celluloses from the results of isothermal runs at six different temperatures. It is postulated here that the thermal degradation occurs by random nucleation and nucleus growth in the cellulose fibrils so as to yield a carbon whose microporous structure is a replica of the pore system in the parent cellulose. 相似文献
9.
The conditions of thermal decomposition of thep-aminosalicylates of Y, La and the lanthanides from Ce(III) to Lu have been studied. On heating, the hydrated complexes of La and the light lanthanides decompose to the oxides with the intermediate formation of Ln2[H2N·C6H3(O)COO]3. Only the complex of La decomposes to La2O3 through La2[H2N·C6H3(O)COO]3 and La2O2CO3. The anhydrous complexes of the heavy lanthanides decompose directly to the oxides, whereas the anhydrous complex of Y decomposes to Y2O3 via Y2[H2N·C6H3(O)COO]3 formation. During heating, the hydrated complexes lose crystallization water and decompose simultaneously, and the endothermic effect of dehydration is masked by the strong exothermic effect of burning of the organic ligand.
Zusammenfassung Es wurden die Bedingungen für die thermische Zersetzung derp-Aminosalicylate von Y, La und der Lanthanoide von Ce(III) bis Lu untersucht. Beim Erhitzen zersetzen sich die hydratierten Komplexe von La und der leichteren Lanthanoide unter Bildung des Zwischenproduktes Ln2[H2NC6H3(O)COO]3 in ihre Oxide. Nur der Komplex mit La zersetzt sich zu La2O3 über die Zwischenstufen La2[H2NC6H3(O)COO]3 und La2O2CO3. Die wasserfreien Komplexe der schweren Lanthanoide zersetzen sich direkt in die Oxide, wÄhrend sich der wasserfreie Komplex von Y über die Bildung von y2[H2NC6H3(O)COO]3 in y2O3 zersetzt. Beim Erhitzen verlieren die hydratierten Komplexe ihr Kristallwasser und zersetzen sich gleichzeitig, der endotherme Effekt der Dehydratation wird durch den starken exothermen Effekt der Verbrennung der organischen Liganden überdeckt.相似文献
10.
Anca Mihaela Mocanu Lucia Odochian N. Apostolescu C. Moldoveanu 《Journal of Thermal Analysis and Calorimetry》2011,103(1):283-291
The article is devoted to a comparative study on the thermal degradation of some new diazoaminoderivatives under both air
and nitrogen atmosphere by TG-FTIR analysis. The TG–DTG–DTA curves show the thermal degradation in air to present two temperature
domains: an endothermic one identical to the case of the degradation under nitrogen and an exothermic one which is not to
be found under nitrogen atmosphere. The identification of the gaseous species released by degradation in air within the endothermic
domain made evident the presence of the same components of the degradation in nitrogen atmosphere. In the exothermic domain
of the sample degradation in air, the CO2, H2O, SO2 species result by the burning of the molecular residues of the first domain. The obtained results afforded a degradation
mechanism to be advanced that coincide for the endothermic domain with that of degradation under nitrogen atmosphere. Due
to the importance of these compounds as possible reaction initiators and also as potentially bioactive substances (herbicides,
acaricides, fungicides), the study on their thermal degradation could give useful information on the environmental impact
of the degradation products resulting by the thermal processing of the plants which could possible retain these compounds,
when the initial degradation temperature is exceeded. 相似文献
11.
Yanhua Liu 《Thermochimica Acta》2004,414(2):121-123
Dynamic kinetic analyses were performed on basic zinc carbonate using TG and DTA measurements in N2. The thermal behavior and the kinetics of decomposition were studied. The effect of procedural variables on the kinetics was investigated. In this work, the procedural variables included heating rate and sample size. To estimate the activation energy of decomposition, the Friedman isoconversional method was applied. The activation energy (Ea) was calculated as a function of conversion (a). 相似文献
12.
The conditions of thermal decomposition of Y, La and lanthanide (from Ce(III) to Lu) pyromucates have been studied. On heating, these complexes decompose in various ways: La, Pr, Nd and Sm pyromucates in four stages, Ce, Eu, Gd, Dy, Ho and Er pyromucates in three stages, and Tm, Yb, Lu and Y pyromucates in two stages, the oxides finally being formed. The hydrated complexes (from La to Er) lose crystallization water to form anhydrous salts. The anhydrous complexes of La, Pr, Nd and Sm decompose to oxides through the intermediate formation of unstable oxypyromucates and Ln2O2CO3, whereas the anhydrous complexes of Ce(III), Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu decompose to the oxides through the intermediate formation of oxypyromucates. The temperatures of dehydration and oxide formation change periodically with increasing atomic number in the lanthanide series.
Zusammenfassung Die Bedingungen der thermischen Zersetzung der Pyromucate von Y, La und den Lanthaniden (Ce(III) bis Lu) wurden untersucht. Beim Erhitzen zersetzen sich die Komplexe auf verschiedene Weise: die Pyromucate von La, Pr, Nd und Sm in 4 Schritten, die von Ce, Eu, Gd, Dy, Hod Er in 3 Schritten und die von Tm, Yb, Lu und Y in nur 2 Schritten. Endprodukte der Zersetzung sind die Oxide, Die hydratisierten Komplexe von La bis Er verlieren Kristallwasser unter Bildung der wasserfreien Salze. Die wasserfreien Komplexe von La, Pr, Nd und Sm zersetzen sich zu Oxiden über instabile Oxypyromucate und Ln2O2CO3 als Zwischenprodukte, bei der Zersetzung der wasserfreien Komplexe von Ce(III), Eu, Gd, Dy, Ho, Er, Tm, Yb und Lu werden Oxypyromucate als Zwischenprodukte gebildet. Die Temperaturen der Dehydratisierung und Oxidbildung schwanken periodisch mit ansteigender Atomzahl in der Lanthanidenreihe.
, ( ) . : , , , , , , , — , , , — . , . , , Ln2O2CO3. . .相似文献
13.
The conditions of decomposition of Y, La and lanthanide (from Ce(III) to Lu) salicylates have been studied. On heating, the hydrated salicylates of Y and lanthanides from Nd to Lu lose crystallization water in one step to yield the anhydrous salts. The anhydrous complexes of Y, La, Ce(III), Pr, Nd, Sm, Eu(III), Gd and Tb subsequently decompose in several steps to the oxides Ln2O3, CeO2, Pr6O11 and Tb4O7. The anhydrous complexes of the remaining lanthanides decompose directly to the oxides Ln2O3.
Zusammenfassung Die Zersetzungsreaktionsbedingungen von Y-, La- und Lanthanid-(Ce(III) bis Lu) salizylaten wurden untersucht. Beim Erhitzen geben hydrierte Salizylate von Y und der Lanthanide Nd bis Lu Kristallwasser in einem Schritt ab und bilden wasserfreie Salze. Die wasserfreien Komplexe von Y, La, Ce(III), Pr, Nd, Sm, Eu(III), Gd und Tb zersetzen sich in mehreren Schritten und bilden die Oxide Ln2O3, CeO2, Pr6O11 und Tb4O7. Die wasserfreien Komplexe der übrigen Lanthaniden zerfallen direkt in Ln2O3 Oxide.
, . , . , , , , , , , , Ln2O3, CeO2, Pr6O11 47. Ln2O3.相似文献
14.
Joseph M. Augl 《Journal of polymer science. Part A, Polymer chemistry》1972,10(8):2403-2424
A series of poly[2,2′-(1,4-phenylene)-6,6′-bis(3-phenylquinoxalines)] were prepared. These polymers had all the same repeating unit but differed in molecular weight and polymer chain endings. The thermal degradation characteristics in air and vacuum were determined by isothermal weight loss measurements. The temperature coefficients of thermal degradation (apparent activation energies) were also determined. Whereas the apparent activation energies for degradation in air showed a considerable dependency on the type of polymer chain endings, no such effect was observed upon pyrolysis in vacuo. A possible chain-end unzipping mechanism of degradation in air is postulated to explain these results. 相似文献
15.
Xue-Gang Chen Shuang-Shuang Lv Ping-Ping Zhang Lu Zhang Ying Ye 《Journal of Thermal Analysis and Calorimetry》2011,104(3):1055-1062
In this study, we ashed rice hull in air and nitrogen, respectively, and systematically investigated the effects of ashing temperature and atmosphere on the structures, morphologies, and pore characteristics of rice hull ash (RHA). All RHA samples are amorphous materials with porous structures. IR spectra revealed that RHA that ashed in air (WRHA) exhibit more polar groups on the surface than that of ashed in nitrogen (BRHA). The silica and carbon contents, BET surface area, and pore volume of BRHA increase with ashing temperature. When ashed in air, however, the silica content of WRHA increases and carbon content decreases with temperature. The BET surface area and pore volume of WRHA increase with temperature firstly and decline subsequently due to the closure of pores. Compared with WRHA, BRHA shows higher surface areas, micropore volumes, carbon contents, and lower mesopore fractions and silica contents. This study provides essential information for choosing a suitable thermal treatment of rice hull for a given adsorbate. 相似文献
16.
17.
The condition of thermal decomposition of La, Ce(III), Pr(III), Nd, Sm, Eu(III), Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu suberates were studied. The suberates of Ce(III), Sm, Eu(III), Ho, Tm, Yb and Lu heated lose crystallization water. Anhydrous Sm and Eu(III) suberates decompose to oxides with intermediate formation Ln2O2CO3, whereas suberates of other lanthanides decompose directly to oxides. Suberates of La, Pr(III), Nd, Gd, Tb, Dy and Er lose some water molecules and then decompose directly to oxides. Only La complex decomposes to La2O3 via the intermediate formation La2O2CO3.
Zusammenfassung Es wurden die UmstÄnde der thermischen Zersetzung von La-, Ce(III)-, Pr(III)-, Nd-, Sm-, Eu(III)-, Gd-, Tb-, Dy-, Ho-, Er-, Tm-, Yb- und Lu-suberat untersucht. Bei Erhitzen verlieren Ce(III)-, Sm-, Eu(III)-, Ho-, Tm-, Yb- und Lu-suberat Kristallwasser. Wasserfreies Sm-bzw. Eu(III)-suberat zersetzt sich über das Zwischenprodukt der Zusammensetzung Ln2O2CO3 zum Oxid, wÄhrend sich die Suberate der anderen Lanthanoide direkt zu den Oxiden zersetzen. La-, Pr(III)-, Nd-, Gd-, Tb-, Dy- und Er-suberat geben einige Moleküle Kristallwasser ab und zersetzen sich dann direkt zu den Oxiden. Nur der Lanthankomplex zersetzt sich zu La2O3 über das Zwischenprodukt La2O2CO3.相似文献
18.
H. H. G. Jellinek H. Fujiwara 《Journal of polymer science. Part A, Polymer chemistry》1972,10(6):1719-1728
The thermal degradation of poly-p-oxybenzoate in vacuo as function of temperature has been studied. The energy of activation of the process up to about 30% volatile formation is 59.6 kcal/mole. The degradation is preceded by induction periods, which have been shown to be due to poor heat conductivity of the polymer powder. CO, CO2, phenol, and an unknown compound of molecular weight larger than 200 are the main degradation products found by chromatographic analysis. Infrared spectra of the original polymer, the polymer residue after degradation and of a degradation product solid at room temperature are presented. The possible reactions taking place have been indicated. The heat stability of the polymer in vacuo lies between those of polytetra-fluoroethylene and polyethylene. 相似文献
19.
Thermal
degradation of wood treated with flame retardants 总被引:2,自引:0,他引:2
Wood,
one of the most flammable materials, was treated with various compounds containing
nitrogen, phosphorus, halogens, and boron. For a study of flame retardance
from the standpoint of thermal degradation, the samples were subjected to
thermogravimetry (TG), differential thermal analysis (DTA) and differential
thermogravimetry (DTG) in nitrogen to determine if there were any characteristic
correlations between thermal degradation behaviors and the level of flame
retardance. From the resulting data, kinetic parameters for different stages
of thermal degradation are obtained using the method of Broido. The energies
of activation for the decomposition of samples are found to be from 72 to
109 kJ mol–1. For wood and modified wood,
the char yields are found to increase from 10.2 to 30.2%, LOI from 18 to 36.5,
which indicates that the flame retardance of wood treated with compounds is
improved. The flame retardant mechanism of different compounds has also been
proposed. 相似文献
20.
Claudia Aparicio Libor Machala Zdenek Marusak 《Journal of Thermal Analysis and Calorimetry》2012,110(2):661-669
The thermal decomposition of Prussian blue (iron(III) hexacyanoferrate) under inert atmosphere of argon was monitored by thermal analysis from room temperature up to 1000?°C. X-ray powder diffraction and 57Fe M?ssbauer spectroscopy were the techniques used for phase identification before and after sample heating. The decomposition reaction is based on a successive release of cyanide groups from the Prussian blue structure. Three principal stages were observed including dehydration, change of crystal structure of Prussian blue, and its decomposition. At 400?°C, a monoclinic Prussian blue analogue was identified, while at higher temperatures the formation of various polymorphs of iron carbides was observed, including an orthorhombic Fe2C. Increase in the temperature above 700?°C induced decomposition of primarily formed Fe7C3 and Fe2C iron carbides into cementite, metallic iron, and graphite. The overall decomposition reaction can be expressed as follows: Fe4[Fe(CN)6]3·4H2O????4Fe?+?Fe3C?+?7C?+?5(CN)2?+?4N2?+?4H2O. 相似文献