The thermal analysis of lipids isolated from various tissues of deers and does

TG analysis of lipids is a suitable analytical method that offers the possibility to correlate kinetic parameters of thermal degradation (activation energy) and lipid composition. For this purpose, an inert (nitrogen) or oxidising atmosphere (oxygen) was applied during the thermal treatment (30–220°C) of lipids isolated from intramuscular and fatty tissues (L-IMT and L-FT) of deers and does. Prior to investigation, the extracted samples of lipids were kept at –24°C or +4°C for nine months, thus enabling detection of the influence of storage temperature on the thermal behaviour of the lipids.     

The Thermal Degradation of Alkaline Earth Metal Salts of Poly(Itaconic Acid)

The Mg-, Ca- and Ba-salts of poly(itaconic acid) (PIA) were prepared by treating the aqueous solution of the polyacid with the corresponding metal oxide or hydroxide. The resulting polysalts were analysed by FTIR spectroscopy and thermogravimetry. The results indicate that the polysalts are thermally more stable than the parent PIA, they all degrade in a similar manner, the Ba-salt being the most stable. This revised version was published online in August 2006 with corrections to the Cover Date.     

EGA/MS Investigations on the Thermal Degradation of Diammoniumhexachloroplatinate

The thermal degradation of diammoniumhexachloroplatinate (NH₄)₂PtCl₆ is used in technical scale for the production of the pure platinum metal [1] and for this reason of great interest. Our investigations have been focused on the influence of the different atmospheres (oxidizing, inert or reducing) used in the technical processes towards the degradation mechanism and the evolved volatile degradation products. The second main aspect of our investigations was the evolution of volatile platinum species. Regarding the different frequencies of platinum allergies related to the different technical processes, the evolution of volatile platinum species is of great importance, due to the supposed allergic potential of this substances [2–4]. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermogravimetric study of aerobic biodegradation of sanitary sewage sludge and lubricating oil

The present study describes the aerobic biodegradation process of a mixture of sanitary sewage sludge and lubricating oil. TG/DTG curves confirmed that the applied aerobic biological treatment decreased the organic material content and caused significant modifications in the thermal behavior of the studied substrates after the functioning period.     

Degradation behavior and kinetic study of ABS polymer

The degradation kinetics of the ABS terpolymer (acrylonitrile-butadiene-styrene) was investigated by means of thermogravimetric analysis. The samples were heated from 30 to 900°C in nitrogen atmosphere applying three different heating rates: 5, 10 and 20°C min⁻¹. The Vyazovkin model-free kinetic method was used to calculate the activation energy (E) of the degradation process as a function of conversion and temperature. Between 20 and 80% of conversion, E was calculated and the figures were: for ABS GP, E is 204.5±11.5 kJ mol⁻¹ (medium value); for ABS HI, E is 239.0±9.8 kJ mol⁻¹; for ABS HH, E is 242.4±5.4 kJ mol⁻¹.     

聚芳醚醚酮的热老化寿命研究

本工作用热重法(TG)研究了聚芳醚醚酮(PEEK)在空气和氮气中的热分解反应过程;确定了PEEK在这两种气氛中的热分解反应模型均符合无规引发断裂模型;在空气中PEEK的热分解显示两个过程,由此计算其在空气中第一阶段的热分解和氮气中的热分解反应活化能分别为214.7kJ/mol和232.2kJ/mol;由热分解反应动力学参数推算出热老化寿命曲线,并讨论了实验条件对结果的影响,进而以失重5%作为材料寿终指标估算出PEEK在氮气和空气中使用10年的最高温度分别为307℃和274℃。     

DNA-bound lipids: computer modeling of DNA interaction with stearic acid and unsaturated fatty acids

It was shown for the first time by computer experiments that fatty acids are strongly bound to DNA. This is consistent with the presence of free fatty acids in the specimens of DNA-bound lipids isolated from various cells. Binding of all fatty acids to the DNA minor groove is stronger than to the major groove, which is correlated with the presence of two pools of free fatty acids isolated from DNA specimens by biochemical methods. Since DNA polymerase is also bound to the DNA minor groove, fatty acids can play an important role in the regulation mechanism of DNA replication and signal transmission. The energy of interaction of fatty acids with DNA depends on both the number of double bonds and the geometric configuration of the fatty acid and the nucleotide composition of DNA. Dependence on the bond energy in the DNA—fatty acid complex on the nucleotide composition attests to the possibility of site-specific binding of lipids to DNA. On passing from a saturated fatty acid to unsaturated acids containing one, two, or three double trans-bonds, the bond energy of DNA with the fatty acid gradually decreases. The presence of one or three double cis-bonds results in weakening of the strength of the DNA—fatty acid complexes compared to those with the saturated acid. The strongest binding between DNA and fatty acid was found for the unsaturated acid with two double cis-bonds (linoleic). This can be explained by the fact that the bent (boomerang) shape of the molecule of this acid follows the curve of the DNA helix. The pattern of variation of the energy of DNA complexes with stearic, linoleic, oleic, and linolenic acids correlates with experimental data on the melting points of these complexes: the more stable the DNA—fatty acid complex, the lower the melting point of DNA.     

Enhancement of PUR/PIR foam thermal stability after addition of Zostera marina biomass component investigated via thermal analysis and isoconversional kinetics

In the present work, a thorough thermogravimetric (TG) analysis of bio-based polyurethane–polyisocyanurate (PUR–PIR) foams in both nitrogen and oxygen atmosphere is performed. A sustainable element of the foam is a biopolyol obtained via acid-catalyzed liquefaction of Zostera marina and Enteromorpha Algae biomass. Based on isoconversional analysis and apparent activation energies, several conclusions are obtained. In contradiction to the common understanding, biopolyol based foams exhibit enhanced stability in both oxidative atmosphere and in nitrogen compared to purely petrochemical foams. Relationships between thermal stability and structure of the foams are established. Enhanced stability of bio-based foams in oxygen is attributed to two factors. First is an increased cross-linking density due to higher hydroxyl number of biopolyol compared to petrochemical one. Possibly the presence of more amount of aromatic compounds in the structure of polyols that come from lignin or aromatic ketones contribute to further enhancement of thermal stability. Those results suggest that the studied biobased foams are prospective alternatives to standard petrochemical PUR foams.     

Neutral lipids from seeds of Asteraceae plants

Lipids from seeds of three plants of the Asteraceae family, Cousinia franchetii, Arctium leiospermum, and Rhaponticum integrifolium, were studied. The principal constituents of lipids from the three plants were shown to be acylglycerides of ordinary fatty acids and oxygenated fatty acids using chemical and chromatographic analyses. The composition of the ordinary unoxidized and epoxy acids was determined by GC. Presented at the 7th International Symposium on the Chemistry of Natural Compounds, October 16–18, 2007, Tashkent, Uzbekistan __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 115–117, March–April, 2008.     

Aspects of metallurgical activity in Liguria (Italy) in the middle and late bronze age

Prehistoric metal findings from Liguria are numerous, however, even though there were many metalliferous mines, the metal-working sites have not yet been ascertained.This work discusses results on some metal objects from different archaeological sites in Liguria.The objects examined were: 1) two melting drops 2) an axe, and 3) a knife. The physico-chemical investigation techniques employed were:

Thermal degradation of organo-soluble polyimides

The thermal degradation behavior of two organo-soluble polyimides was investigated by high resolution pyrolysis-gas chromatography/mass spectrometry. The pyrolyzates of the polymers at various temperatures were identified and characterized quantitatively. The relationship between the polymer structure and pyrolyzate distribution was discussed. The kinetic parameters of the thermal degradation were calculated based on thermogravimetric measurements. Finally, the thermal degradation mechanism for the polymers was suggested.     

Characterization of the Synergistic Effect between Ligands of Opioid and Free Fatty Acid Receptors in the Mouse Model of Colitis

Background: Recent studies suggest that lipids, including free fatty acids (FFAs), are necessary for proper μ opioid receptor (MOR) binding and that activation of opioid receptors (ORs) improves intestinal inflammation. The objective of the study was to investigate a possible interaction between the ORs and FFA receptors (FFARs) ligands in the colitis. Methods: The potential synergistic effect of ORs and FFARs ligands was evaluated using mouse model of acute colitis induced by dextran sulfate sodium (DSS, 4%). Compounds were injected intraperitoneally (i.p.) once or twice daily at the doses of 0.01 or 0.02 mg/kg body weight (BW) (DAMGO—an MOR agonist), 0.3 mg/kg BW (DPDPE—a δ OR (DOR) agonist) and 1 mg/kg BW (naloxone—a non-selective OR antagonist, GLPG 0974—a FFAR2 antagonist, GSK 137647—a FFAR4 agonist and AH 7614—a FFAR4 antagonist) for 4 days. Results: Myeloperoxidase (MPO) activity was significantly decreased after DAMGO (0.02 mg/kg BW) and GSK 137647 (1 mg/kg BW) administration and co-administration as compared to DSS group. Conclusions: Treatment with ligands of ORs and FFARs may affect the immune cells in the inflammation; however, no significant influence on the severity of colitis and no synergistic effect were observed.     

Investigation of thermal behavior of nicotinic acid

The thermal behavior of nicotinic acid under inert conditions was investigated by TG, FTIR and TG/DSC-FTIR. The results of TG/DSC-FTIR and FTIR indicated that the thermal behavior of nicotinic acid can be divided into four stages: a solid-solid phase transition (176–198°C), the process of sublimation (198–232°C), melting (232–263°C) and evaporation (263–325°C) when experiment was performed at the heating rate of 20 K min⁻¹. The thermal analysis kinetic calculation of the second stage (sublimation) and the fourth stage (evaporation) were carried out respectively. Heating rates of 1, 1.5, 2 and 3 K min⁻¹ were used to determine the sublimation kinetics. The apparent activation energy, pre-exponential factor and the most probable model function were obtained by using the master plots method. The results indicated that sublimation process can be described by one-dimensional phase boundary reaction, g(α)=α. And the ‘kinetic triplet’ of evaporation process was also given at higher heating rates of 15, 20, 25, 30 and 35 K min⁻¹. Evaporation process can be described by model of nucleation and nucleus growing, .     

Thermal degradation of polymethacrylic acid

The thermal degradation of polymethacrylic acid was found to have two separate decomposition regions. The first decomposition region, due to anhydride formation primarily, was caused by the conversion of polymethacrylic acid to polymethacrylic anhydride. This reaction followed first-order kinetics and had an activation energy of 40.5 kcal/mol. The second decomposition region was the thermal degradation for the corresponding polymethacrylic anhydride. In this region, the fragmentation of anhydride rings structure in polymethacrylic anhydride constitutes the major decomposition reaction with an activation energy of 37.4 kcal/mol. © 1992 John Wiley & Sons, Inc.     

Calorimetric study of the component steps of oscillating chemical reactions

An influence of inorganic compounds (Fe₂O₃, ZnO, PbO, CaCO₃ and K₂CO₃) on the blast furnace coke thermal oxidation in the air and in the CO₂atmosphere was investigated by means of thermal analysis. A catalytic effect showed itself at the oxidation in the air, especially with PbO and K₂CO₃. These compounds bring the oxidation starting temperature and activation energy down and increase the reaction rate constant most distinctly. The PbO and K₂CO₃ actions differ in their mechanisms. K₂CO₃ accelerates particularly the amorphous coke fractions oxidation. In the CO₂ atmosphere an important catalytic effect occurred only with K₂CO₃. The PbO catalytic influence is less distinct. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cofactors in Biota: results of a German interlaboratory exercise on the determination of total lipids in fish tissue

 The content of total lipids is a common cofactor necessary for a normalisation of organic contaminant concentrations in biological materials. Lipids are routinely determined gravimetrically after extraction of the material with chlorinated solvents. A new method substituting chlorinated solvents for a cyclohexane/isopropanol mixture was to be evaluated by an intercomparison exercise. The participating laboratories were requested to determine total lipid content in three different samples of fish tissue following their own procedures as well as the new method described in a standard protocol. No significant differences in the overall means of total lipid content were found for the investigated samples regardless of the determination method. Using the harmonised protocol of the new method, between laboratory reproducibilities below 10% were obtained in the exercise. The results indicate the applicability of the harmonised method for the determination of total lipids as a cofactor in the analyses of contaminant concentrations in marine biota samples. Received: 27 June 2000 / Accepted: 20 September 2000     

Synthesis of sulfur-containing cationic lipids of the 1,3-dioxolane type

A series of cationic acetal lipids containing different spacer and cationic groups were synthesized starting from 1,2-O-hexadecylidene-3-thioglycerol. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1590–1592, August, 1998.