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1.
Edilene Pereira Lavor Marco Vinícius M. Navarro Fátima D. Freire Cícero F. S. Aragão Fernanda Nervo Raffin Euzébio Guimarães Barbosa Túlio F. A. de Lima e Moura 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2303-2309
First-line drugs (rifampicin, RIF; isoniazid, INH; ethambutol, ETA; and pyrazinamide, PZA) recommended in conventional treatment of tuberculosis were analyzed in 1:1 w/w binary mixtures with microcrystalline cellulose MC 101 (CEL) and lactose supertab® (LAC) by differential scanning calorimetry (DSC), thermogravimetry (TG), differential thermal analysis (DTA), and Fourier transformed infrared analysis (FTIR) as part of development of fixed dose combination (FDC) tablets. Evidence of interaction between drug and pharmaceutical excipients was supposed when peaks disappearance or shifting were observed on DTA and DSC curves, as well as decreasing of decomposition temperature onset and TG profiles, comparing to pure species data submitted to the same conditions. LAC was showed to interact with RIF (absence of drug fusion and recrystallization events on DSC/DTA curves); INH (thermal events of the mixtures different from those observed for drug and excipient pure in DSC/DTA curves); PZA (decrease on drug fusion peak in DSC/DTA curves), and ETA (shift on drug onset fusion and absence of pure LAC events on DSC/DTA curves). In all cases, an important decrease on the temperature of drug decomposition was verified for the mixtures (TG analysis). However, FTIR analysis showed good correlation between theoretical and experimental drug-LAC spectra except for INH–LAC mixture, evidencing high incompatibility between these two species and suggesting that those interactions with PZA and RIF were thermally induced. No evidence of incompatibilities in CEL mixtures was observed to any of the four-studied drugs. 相似文献
2.
W.W. Wendlandt 《Thermochimica Acta》1975,12(4):359-366
The TG, DTG, DTA, DSC, EC and dilatometric curves of SrCi2-6H2O are presented. Intermediate hydrates having the composition, SrCl2-2H2O and SrCl2-H2O, were detected while there was evidence for SrCl2-0.5H2O in the high pressure DSC curves. DSC curves for this compound were obtained at pressures from 0.2 to 50 atm. 相似文献
3.
Roseany V. V. Lopes Nuno Pedro D. Loureiro José R. Zamian Pâmela S. Fonseca Júlio L. Macedo Maria L. dos Santos Maria J. A. Sales 《Macromolecular Symposia》2009,286(1):89-94
Although the petrochemical polymers have revolutionized the technological development, the intensive use of these materials have contributed to the global pollution. In this context, researches involving ecofriendliness materials are growing up, as well as, a current interest in developing materials from inexpensive and renewable resources, such as vegetable oils. In this work, is described the synthesis of polymeric materials by thermal polymerization from linseed oil (Linum usitatissimum L.) and passion fruit oil (Passiflora edulis) and their characterization by gas chromatographic (GC), Fourier transform infrared (FTIR) spectroscopy, solubility in organic solvents, thermogravimetry (TG), differential scanning calorimetry (DSC) and Raman spectroscopy. The TG curve shows that those polymeric materials present two stages of decomposition. DSC plots of the vegetable oils showed some endothermic and exothermic transitions which are not present in the DSC curves corresponding to oil-based polymers. The Raman spectra of the polymers indicate declining of absorbance in the region of CC stretching (∼1600 cm−1). This absorption was used to estimate the degree of polymerization (79% and 67.5% for linseed and passion fruit oils, respectively). 相似文献
4.
Ksenia V. Zherikova Natalia B. Morozova Ludmila N. Zelenina S. V. Sysoev Tamara P. Chusova I. K. Igumenov 《Journal of Thermal Analysis and Calorimetry》2008,92(3):729-734
Five volatile hafnium(IV) and zirconium(IV) β-diketonates: hafnium(IV) acetylacetonate, hafnium(IV) trifluoroacetylacetonate,
hafnium(IV) pivaloyltrifluoroacetonate, hafnium(IV) 2,2,6,6-tetramethylheptane-3,5-dionate and zirconium(IV) 2,2,6,6-tetramethylheptane-3,5-dionate
were obtained, purified and identified. Thermal behavior of solid compounds was investigated by thermogravimetry (TG) and
differential scanning calorimetry (DSC) in helium atmosphere and in vacuum. DSC method was also used for definition of thermodynamic
characteristics of melting processes. Using the static method with quartz membrane zero-manometer and the flow method the
temperature dependencies of saturated vapor pressure for hafnium(IV) complexes was obtained. The standard thermodynamic characteristics
ΔH
T0 and ΔS
T0 of sublimation and evaporation processes were calculated from the temperature dependences of saturated vapor pressure. 相似文献
5.
Russany Silva da Costa Charles Alberto Brito Negrão Sarah Regina Pereira Camelo Roseane Maria Ribeiro-Costa Wagner Luiz Ramos Barbosa Carlos Emmerson Ferreira da Costa José Otávio Carréra Silva Júnior 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1959-1964
Thermogravimetric (TG) techniques and differential scanning calorimetry (DSC) used for the study of pre-formulation or drug–adjuvant compatibility have been gaining importance in Brazil. These techniques are being used for the verification of possible interactions between drugs and adjuvants. Aiming at studying the behavior of a plant extract and its mixture with adjuvants, using these thermoanalytical techniques the plant species Heliotropium indicum L. was used. This plant which is originally from India and has been well acclimatized in Brazil has healing and anti-inflammatory properties. The methodology for obtaining the extract followed the Brazilian Pharmacopoeia methodology. And the incorporation of the extract with adjuvants was through binary mixtures (1:1 w/w). The TG and DSC curves were obtained under nitrogen atmosphere (25 mL min?1) at a heating rate of 5 °C min?1; TG tests were analyzed within a temperature range from 25 to 600 °C and DSC from 25 to 300 °C. The TG curves show good thermal stability of the extract and its mixtures with adjuvants up to 150 °C, except the propylene glycol (PLG). The DSC curves revealed an incompatibility of the extract with methylparaben and PLG mixture. 相似文献
6.
Laércio Gomes Lage 《European Polymer Journal》2004,40(7):1309-1316
The vibrational spectra of Nafion® membranes with alkaline earth cations as counterions have been obtained by photoacoustic infrared spectroscopy (PAS-IR) and Fourier transform Raman spectroscopy (FT-Raman). The symmetrical stretching band of the sulfonate group (∼1060 cm−1) decreases with increasing atomic mass of the countercation, excepting for Mg2+, in both techniques. The thermal behavior of Nafion membranes by means of differential scanning calorimetry (DSC) curves showed a dependence on the water content and a similar profile between Nafion-Mg2+ and -Ca2+, and between Nafion-Sr2+ and -Ba2+, for the first scanning curve. An ageing effect was also observed on Nafion by DSC curves. High-resolution thermogravimetry (TG) curves under nitrogen atmosphere showed similar decomposition profiles. It was determined from TG curves that there is a decreasing water content with increasing ionic radius of cation, and the thermal stability increasing from Nafion-Mg2+ to -Ba2+. 相似文献
7.
《Comptes Rendus Chimie》2016,19(6):707-717
Using water as a green solvent with a variable geometry makes use of physical and chemical phenomena that are fundamentally different from those applied in conventional extraction techniques such as hydro-distillation, steam distillation or solvent extraction. Advantages and drawbacks of using water as a solvent with different physical and chemical states have been compared. A total of ten extraction techniques: hydro-distillation (HD), steam distillation (SD), turbo-hydro-distillation (THD), salt-hydro-distillation (NaCL-HD), enzyme-hydro-distillation (Enzyme-HD), micelle-hydro-distillation (Micelle-HD), ultrasound-hydro-distillation (US-HD) or subcritical water-hydro-distillation (SW-HD), solvent-free microwave extraction (SFME) and microwave steam distillation (MSD) were used to extract the essential oil from lavender (Lavandula L.) and their results were compared. The quantity was measured by the yield of essential oil and the quality was evaluated using the oil composition especially the content of linalyl acetate, linalool and terpin-4-ol compared with the corresponding control sample: Hydro-distillation. For environmentally friendly of the process: extraction time, total energy consumption and CO2 emission were considered and compared with conventional hydro-distillation. The mechanism explaining the linalyl acetate degradation has been resolved by using COSMO-RS software. Based on the present experimental conditions, it is recommended that lavender oil may be produced preferably by steam distillation assisted by microwave extraction to reduce the by-product formation by various chemical reactions and to get better oil recoveries. 相似文献
8.
Yi-Bo Li Jin-Zhou Zhao Wan-Fen Pu Hu Jia Huan Peng Dong Zhong Sheng-Kui Wang 《Journal of Thermal Analysis and Calorimetry》2013,113(2):579-587
This research aimed at the investigation of the effect of different metallic additive on the combustion and kinetic behavior of crude oil. For this purpose, the thermal behavior of the oil-only and oil–metallic salts mixtures were studies by the thermogravimetry (TG)/derivative thermogravimetry and differential scanning calorimetry (DSC) on heating rate at 10 °C min?1. The result shows that Dagang crude oil exhibited apparent low temperature oxidation (LTO), fuel deposition, and high temperature oxidation processes. With the addition of metallic salts, the LTO process has been shortened and samples added CuSO4, CrCl3·6H2O, and AlCl3·6H2O achieved a much lower peak temperature than that of oil. Based on the Arrhenius model, metallic additives were proven to have obvious influence on the combustion activation energy. And, by comprehensive analysis of TG/DSC profile and activation energy, ZnSO4 exhibited a positive influence on light crude oil combustion during the high pressure air injection process. 相似文献
9.
DSC measurements in open pans are often disturbed by mass losses such as sublimation during melting or release of water during
chemical reactions. By simultaneous DSC and TG measurements the DSC signal can be corrected. For this purpose, a temperature
dependent calibration function has to be determined by which the SDTA signal from the TGA/SDTA851e measuring cell can be converted into a heat flow curve (DSC).
By this procedure, accurate heat of melting can be determined despite ongoing sublimation in open pans. This method is illustrated
with reference of the melting of anthracene.
Additionally, condensation reactions were investigated and analyzed by DSC/TG even under ambient pressure, knowing the heat
of evaporation. Using phenol formaldehyde resins the influence of the presence or the release of volatile reaction products
on the reaction rate and kinetic parameters were studied.
In general, the method can be used to correct DSC curves for thermal effects related to mass change.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Daniela Schlemmer E. R. de Oliveira M. J. Araújo Sales 《Journal of Thermal Analysis and Calorimetry》2007,87(3):635-638
Conventional plastics has a
large impact in increasing the environment’s pollution. That’s
why the interest has turned towards novel partially and completely biodegradable
polymers. In this work, blends of polystyrene and thermoplastic starch with
glycerol and Buriti (Mauritia flexuosa
L.) oil as plasticizers were prepared. Samples were analyzed using TG/DTG
and DSC techniques. The TG results indicated that the blends with Buriti oil
are thermally more stable than those with glycerol. The DSC analysis that
Buriti oil provides a higher degree of plasticization of PS, compared to the
blends plasticized using glycerol under the studied conditions. 相似文献
11.
《Fluid Phase Equilibria》1999,154(2):301-310
Isobaric vapor–liquid equilibrium values at 1 atm pressure were measured for the systems 1-propanol–water–potassium acetate and 2-propanol–water–potassium acetate under fixed salt mole fractions using a modified Othmer recirculation still. A modified Furter equation, ln(αs/α)=k1z+k2z2, was proposed for correlating the effect of dissolved salts on vapor–liquid equilibrium (VLE). The modified equation contains two parameters that are applicable to the entire salt/solvent composition range. Correlation of VLE for 15 mixed-solvent electrolyte systems was made by means of the proposed modified equation with better results than those obtained from the original equation. 相似文献
12.
Ana Paula Barrêto Gomes Lidiane Pinto Correia Mônica Oliveira da Silva Simões R. O. Macêdo 《Journal of Thermal Analysis and Calorimetry》2007,88(2):383-387
The objective of this work was to develop
and validate a fast and reproducible method to determine the concentration
of metronidazole in drug substance and tablets. The samples were analyzed
by dynamic thermogravimetry, using 10, 20, 40, 60 and 80°C min–1
heating rates in nitrogen and in nitrogen with synthetic air. Obtained data
were used in the Antoine and Langmuir equations in order to have the pressure
curves. Vapor pressure curves of drug and tablet of metronidazole were evaluated
using the mathematical indexes of difference factor, f
1,
and similarity factor, f
2,
to compare their profiles. The data showed that there is no significant difference
between the vapor pressure profiles of drug and tablet of metronidazole in
both environmental conditions, which confirms that the process is really vaporization.
The concentration of metronidazole was determined in the raw material and
tablets of the drug. 相似文献
13.
M. K. S. Batista M. F. Ginani D. M. A. Melo A. S. Oliveira 《Journal of Thermal Analysis and Calorimetry》2004,75(2):643-647
ZnS(1-x)MSx(x=0.01 and M=Mn2+, Cu2+ and Eu2+) compounds have been obtained by precipitation from homogeneous solutions of zinc, copper, manganese and europium salts,
with S2- as the precipitating anion, formed by the decomposition of thioacetamide. The thermal study of the milled zinc acetate, thioacetamide,
copper acetate, manganese acetate and europium nitrate, respectively, was studied for thermal analyis TG/DSC. XRD respect
exhibits a zinc blend crystal structure.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
J.M. Salas-Peregrin E. Colacio-Rodriguez J.D. Lopez-Gonzalez C. Valenzuela-Calahorro 《Thermochimica Acta》1983,63(2):145-150
Cobalt, copper and cadmium xanthinate tetrahydrates have been prepared in aqueous medium, and characterized on the basis of elemental analysis, IR and 1HNMR studies. The thermal behaviour of these compounds has been studied using TG, DTG and DSC techniques. Heats of dehydration have been calculated from DSC curves. 相似文献
15.
《Fluid Phase Equilibria》2005,227(1):97-112
New mixing rules (VWLC-I and II) capable of connecting van der Waals (VDW) to CEOS/AE mixing rule models were developed. These models are able to incorporate the same multi-component mixture parameters obtained for the van der Waals and CEOS/AE models simultaneously. The VWLC mixing rules directly incorporate local compositions into the cubic equations of state (CEOS). The energy parameters required for the local compositions are calculated from the CEOS parameters. The Peng–Robinson (PR) CEOS was used for this study. Binary interactions parameters were obtained by adjusting the vapor pressure of the binary mixture for several low and high-pressure systems. The predictive capabilities of the VWLC mixing rules were tested by vapor–liquid equilibria calculations for low and high-pressure multicomponent systems. The results were compared with the predictions of the VDW mixing rule and a Huron–Vidal (HV) kind of CEOS/AE-NRTL mixing rule. The VWLC mixing rules are consistent models giving good results in a broad range of pressures and temperatures in binary and multicomponent mixtures. They compare favorably with the CEOS/AE-NRTL mixing rule for low-pressure systems. In high-pressure ternary systems VWLC-I and II give good predictions, much better, in fact, than the CEOS/AE-NRTL mixing rule. 相似文献
16.
Juliana J. R. Pardauil Fábio Alberto de Molfetta Miguel Braga Luiz K. C. de Souza Geraldo N. R. Filho José R. Zamian C. E. F. da Costa 《Journal of Thermal Analysis and Calorimetry》2017,127(2):1221-1229
Thermal profiles of buriti pulp oil (Mauritia flexuosa Mart.), tucumã pulp and kernel oils (Astrocarium vulgare Mart.), rubber seed oil (Hevea brasiliensis), passion fruit oil (Passiflora edulis) and ucuúba butter (Virola surinamensis) were analyzed by thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC). Gas chromatography and calculated iodine values were performed to determine the fatty acid profile and to measure the degree of unsaturation in these oils, respectively. The TG curves showed three steps of mass loss, which can be attributed to the degradation of polyunsaturated, monounsaturated and saturated fatty acids. The DSC crystallization and melting curves are reported and depended on the fatty acid composition. Usually, oil samples with a high degree of saturation showed crystallization and melting profiles at higher temperatures than the oils with a high degree of unsaturation. The data obtained by physicochemical analysis of oil samples were analyzed by principal component analysis and hierarchical cluster analysis to increase understanding of the data set, examining the presence or absence of natural groupings between samples. 相似文献
17.
Ana Paula Barrêto Gomes Lidiane Pinto Correia Mônica Oliveira da Silva Simões Rui Oliveira Macêdo 《Journal of Thermal Analysis and Calorimetry》2007,87(3):919-925
The objective of this work was to develop and validate a fast and reproducible
method able to determine the concentration of mebendazole in raw materials
and tablets. The samples were analyzed by dynamic thermogravimetry, in the
heating rates of 10, 20, 40, 60 and 80°C min–1,
in the atmospheres of nitrogen and nitrogen with synthetic air. Obtained data
were used in the equations of Antoine and Langmuir, with the purpose to get
the pressure curves of those. Vapor pressure curves of drug and tablet of
mebendazole were evaluated using the mathematical indexes of difference factor, f
1, and similarity factor, f
2, to compare its profiles.
The data showed that there is no significant difference between the vapor
pressure profiles of drug and tablet of mebendazole in both environmental
conditions studied, what confirms that the process is really vaporization.
The concentration of mebendazole was determined in the raw material and tablets
with the drug. 相似文献
18.
X. -M. He L. Wang W. -H. Pu J. -G. Ren W. Wu C. -Y. Jiang C. -R. Wan 《Journal of Thermal Analysis and Calorimetry》2008,94(1):151-155
Thermal analysis of sulfurization of polyacrylonitrile (PAN) with elemental sulfur was investigated by thermogravimetry and
differential thermal analysis of the mixture of polyacrylonitrile and elemental sulfur up to 600°C. Due to the volatilization
of sulfur, the different heating rate (10 and 20 K min−1) and different mixture proportion of polyacrylonitrile and elemental sulfur were adopted to run the analysis. The different
heating rates make the DSC curves of sulfur different, but make the DSC curves of PAN similar. In the DSC curve of sulfur
for the heating rate of 20 K min−1 around 400°C, a small exothermic peak occurs at 400°C in the wide endothermic peak around 380∼420°C, indicative of that there
is an exothermic reaction around 400°C. In the DSC curves of the mixture, the peaks around 320°C are exothermic as the content
of sulfur is below 3.5:1 and endothermic as the content of sulfur is over 4:1, indicating that one of the reactions between
PAN and sulfur takes place around 320°C. In the TG curves of the mixture, the mass losses begin at 220°C, and sharply drop
down from 280°C. The curves for the low sulfur content obviously show two steps of mass loss, and curves for the high sulfur
content show only one step of mass loss, indicative of more sulfur is benefit for the complete sulfurization of PAN. This
study demonstrates that the TG/DSC analysis can give the parameter for the sulfurization, even if the starting mixture contains
the volatile sulfur. 相似文献
19.
The water distilled essential oil from dried aerial parts ofStachys ibericasubsp.stenostachya(Lamiaceae) was analyzed by GC/MS. Seventy-one compounds were characterized representing 96% of the oil. The main constituents were found as linalyl acetate (42.2%), linalool (18.9%), geranyl acetate (8.2%), and -terpineol (5.3%). 相似文献
20.
The objective of this work was to develop and validate a fast and reproducible method which is able to determine the concentration
of ketoconazole in raw materials and tablets. The samples were analyzed by dynamic thermogravimetry at heating rates of 10,
20, 40, 60 and 80°C min−1 in nitrogen and nitrogen-synthetic air mixture. The concentrations of ketoconazole in the raw material and in the tablets
were obtained from the vapor pressure curves. The data showed that there is no significant difference between the vapor pressure
profiles of ketoconazole itself and in its tablet in both studied environmental conditions confirming that the process is
really vaporization. The concentration of ketoconazole was determined in the raw material and tablets of the drug. 相似文献