Effects of dietary Clostridium butyricum and rumen protected fat on meat quality,oxidative stability,and chemical composition of finishing goats

Background Clostridium butyricum(CB)is a probiotic that can regulate intestinal microbial composition and improve meat quality.Rumen protected fat(RPF)has been shown to increase the dietary energy density and provide essential fatty acids.However,it is still unknown whether dietary supplementation with CB and RPF exerts beneficial effects on growth performance and nutritional value of goat meat.This study aimed to investigate the effects of dietary CB and RPF supplementation on growth performance,meat quality,oxidative stability,and meat nutritional value of finishing goats.Thirty-two goats(initial body weight,20.5±0.82 kg)were used in a completely randomized block design with a 2 RPF supplementation(0 vs.30 g/d)×2 CB supplementation(0 vs.1.0 g/d)factorial treatment arrangement.The experiment included a 14-d adaptation and 70-d data and sample collection period.The goats were fed a diet consisted of 400 g/kg peanut seedling and 600 g/kg corn-based concentrate(dry matter basis).Result Interaction between CB and RPF was rarely observed on the variables measured,except that shear force was reduced(P<0.05)by adding CB or RPF alone or their combination;the increased intramuscular fat(IMF)content with adding RPF was more pronounced(P<0.05)with CB than without CB addition.The pH24h(P=0.009),a*values(P=0.007),total antioxidant capacity(P=0.050),glutathione peroxidase activities(P=0.006),concentrations of 18:3(P<0.001),20:5(P=0.003)and total polyunsaturated fatty acids(P=0.048)were increased,whereas the L*values(P<0.001),shear force(P=0.050)and malondialdehyde content(P=0.044)were decreased by adding CB.Furthermore,CB supplementation increased essential amino acid(P=0.027),flavor amino acid(P=0.010)and total amino acid contents(P=0.024)as well as upregulated the expression of lipoprotein lipase(P=0.034)and peroxisome proliferator-activated receptorγ(PPARγ)(P=0.012),and downregulated the expression of stearoyl-CoA desaturase(SCD)(P=0.034).The RPF supplementation increased dry matter intake(P=0.005),averaged daily gain(trend,P=0.058),hot carcass weight(P=0.046),backfat thickness(P=0.006),concentrations of 16:0(P<0.001)and c9-18:1(P=0.002),and decreased the shear force(P<0.001),isoleucine(P=0.049)and lysine content(P=0.003)of meat.In addition,the expressions of acetyl-CoA carboxylase(P=0.003),fatty acid synthase(P=0.038),SCD(P<0.001)and PPARγ(P=0.022)were upregulated due to RPF supplementation,resulting in higher(P<0.001)content of IMF.Conclusions CB and RPF could be fed to goats for improving the growth performance,carcass traits and meat quality,and promote fat deposition by upregulating the expression of lipogenic genes of Longissimus thoracis muscle.

Structure Evolution Mechanism of Poly(acrylonitrile/itaconic acid/acrylamide) during Thermal Oxidative Stabilization Process

Polyacrylonitrile （PAN） polymers with different compositions were prepared by an efficient aqueous free-radical polymerization technique. Thermal properties of polyacrylonitrile homopolymer （PAN）, poly（acrylonitrile/itaconic acid） [P（AN/IA）] and poly（acrylonitrile/itaconic acid/acrylamide） [P（AN/IA/AM）] were studied by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetry in detail. It was found that AM had the ability to initiate and accelerate thermal oxidative stabilization process, which was confirmed by the lower initiation temperature and broader exothermic peak in P（AN/IA/AM） as compared with that in P（AN/IA） and PAN. The intensity of heat releasing during the thermal treatment was relaxed due to the presence of two separated exothermic peaks. Accompanied by DSC analysis and calculation of the apparent activation energy of cyclization reaction, two peaks were assigned to the ionic and free radical induction mechanisms, respectively. The higher rate constant in P（AN/IA/AM） indicated that the ionic mechanism actually had a kinetic advantage at promoting thermal stability over the free radical mechanism. This study clearly show that the synthesized P（AN/IA/AM） terpolymers possess larger room to adjust manufacture parameters to fabricate high performance of PAN-based carbon fibers.

Oxidative degradation of sunflower oil blended with roasted sesame oil during heating at frying temperature

The efficacy of roasted sesame oil(SO)on the oxidation deterioration of sunflower oil(SFO)during heating was investigated.The concentrations of SO in the SFO were 0,10%,20%,and 30%by volume.The oxidation profile of oil samples was monitored by evaluating the generation of oxidation products and chemical alterations in the oils'composition during heating at frying temperature(180℃).The results showed that the oxidation parameters(free fatty acid,peroxide value,p-anisidine value,total oxidation status,thiobarbituric acid value,and color index)increased significantly in SFO compared to blends or SO during thermal treatment.During heating,the concentration of polyunsaturated fatty acids(PUFA)was reduced with increased level of saturated fatty acids;these results were observed more in SFO than those of SO or blend oils.However,the presence of SO in SFO reduced the decomposition of PUFA.In Fourier-transform infrared spectroscopy,the peak intensities were significantly altered in SFO compared to the blend oils during heating.Based on the most analytical data,it may be agreed that the heating at frying temperature led to the generation of relatively higher contents of oxidative products in SFO compared to blend oils,showing a lower degree of oxidation occurred in blends.The best frying performance for the SFO was achieved by using 30%SO extracted from the roasted sesame seed.This study showed the proper blending of high polyunsaturated oil with SO can produce oil blends with high nutritional values and enhanced stability for daily cooking and deep-frying applications.

Effects of Dietary Isoflavone Supplementation on Meat Quality and Oxidative Stability During Storage in Lingnan Yellow Broilers

To investigate the effects of a synthetic isoflavone （SI） on meat quality and oxidative stability, 1 500 43-d-old Lingnan yellow male broilers were randomly assigned to five dietary treatments： diets supplemented with 0, 10, 20, 40, or 80 mg SI kg-1, fed ad libitum for a period of 3 wk. After refrigerated storage, a＊ value of the meat increased with dietary SI supplementation using 10 and 40 mg kg-1 level （P〈0.05）, L＊ value decreased （P〈0.05）, and 40 mg kg-j increased the pH （P〈0.05）. Supplementation with SI, at all levels, increased water holding capacity （P〈0.05） and decreased lactic acid content of meat （P〈0.05）. The concentration of malondialdehyde at 72 h decreased linearly （P=0.005） and quadratically （P=0.004） with increasing levels of SI. Dietary SI at 20 and 40 mg kg-1 levels enhanced total superoxide dismutase activity in meat （P〈0.05）. Meat pH quadratically decreased as the storage time increased （P〈0.05）, with the highest value at 24 h （P〈0.05）. Lactic acid and malondialdehyde concentrations of meat increased over time, with value at 96 h being far higher than at earlier times （P〈0.05）. Supplemental SI linearly and quadratically increased the mRNA abundance ofglutathione peroxidase （GPX） （P=0.001 and P=0.002） and catalase （CAT） （P=0.003 and P=0.006） in breast muscle. The results from this study indicate that dietary supplementation with SI can improve meat quality during refrigerated storage by decreasing lipid peroxidation and enhancing oxidative stability and, for male broilers from 43 to 63 d of age, the optimal level of SI was 40 mg kg-1.

Effect of natural and synthetic antioxidants on oxidative stability of FAMEs obtained from hevea brasiliensis

Biodiesel(fatty acid alkyl esters),an alternate to fossil fuel,has the tendency of autoxidation and hence requires antioxidants for long term storage.The influence of synthetic and natural antioxidants on the oxidative stability was analysed for fresh FAMEs(fatty acid methyl esters)obtained from hevea brasiliensis at 140 C.Higher activity was observed for synthetic antioxidants following the order of GA】BHT】DTBP】Q】GT-M】PH-M】GT-C,whereas the oxidative stability of stored FAMEs samples measured at 110 C reveals a nearly inverse trend.Storage stability was tested for the FAMEs obtained from hevea brasiliensis stored at 30 C,after addition of synthetic and natural antioxidants—butylated hydroxytoluene(BHT),2,6-di-tert-butylphenol(DTBP),quercetin(Q),gallic acid(GA),methanol extracts from green tea(GTM),pomegranate hull(PH-M),and chloroform extract of green tea(GT-C).Antioxidant activities above 1500 ppm was in the order of DTBP】BHT】GA】GT-C】GT-M】Q】PH-M.Synthetic antioxidants have been found more efficient to improve the storage stability of FAMEs obtained from hevea brasiliensis.DTBP in particular has the highest protection factor.

Effect of laccase from Trametes versicolor on the oxidative stability of edible vegetable oils

The increasing demand of natural food from consumers has limited the use of traditional methods to control the oxidation of lipids,such as synthetic antioxidants and hydrogenation.Besides,it has been reported that the use of enzymes is efficient to eliminate dissolved oxygen in foods such as vegetable oils.Laccase is a polyphenol oxidase and the reduction of oxygen to water is accompanied by the oxidation,typically,of a phenolic substrate.Laccase have become important,industrially relevant enzymes that can be used for a number of diverse applications such waste detoxification,textile dye transformation,food technologic uses,biosensor and analytical applications,bioethanol production,among others.The target of this study was to evaluate the effect of laccase enzyme from Trametes versicolor,on the oxidative stability of sesame,chia,peanut and sunflower oils,measured through the peroxide value(PV)and conjugated dienes(K232)and trienes(K270).The samples of oil with laccase showed higher PV,K232 and K270 than their corresponding controls,under the conditions evaluated(room temperature and 60◦C).The results suggest that fungal laccase has an unexpected pro-oxidant effect on vegetable oils,possibly promoted by products derived from the oxidation of phenols by enzymatic action.

Effects of Creatine Monohydrate Diet on Muscle Metabolism,Quality,Sensory and Oxidative Stability of Pork in Female,Entire and Castrated Male Pigs

Forty-two (42) finishing pigs (entire males—EM, surgical castrates—SC and gilts—G, each of 14)—progeny of Landracesows and Hampshire × Pietrain boars, were included in the trial. They were randomly divided into control and experimental groups(each of seven). Control groups were fed the standard diet without any supplement. Experimental groups received standard diet withthe same composition as control but with supplement of creatine monohydrate (CMH, 2.0 g/kg of feed) for 30 d prior to slaughter.Sex of pigs had significant effect (p < 0.05) on drip loss and tenderness of pork when EM showed higher drip loss than SC and lowertenderness compared to other two groups (4.71% vs. 3.80%, resp. 3.23 vs. 3.91 and 4.12). Creatine level in plasma was increased byCMH supplementation in 46% in EM, 43% in SC and 41% in G. Similarly, concentration of phosphocreatine (PCr) in muscleincreased in 84% in EM, 88% in SC and 83% in G, respectively. CMH also improved meat colour L* (50.03 vs. 48.88) and reduceddrip loss in both EM (5.24% vs. 4.18%) and G (4.48% vs. 3.60%). Higher tenderness and better oxidative stability of pork after CMHsupplementation was found in all three sexes.

Kinetic Study of the Oxidative Degradation of Choiba Oil(Dipteryx oleifera Benth.)with Addition of Rosemary Extract(Rosmarinus officinalis L.)

Choibá (Dipteryx oleifera Benth.) is a promising source of edible oil with high nutritional quality and a significant content of oleic acid (52% - 54%). To promote Choibá as source of edible oil is necessary to ensure its stability along the time of production, distribution and storage. Loss of nutritional and organoleptic quality in lipids is mainly due to lipid peroxidation reactions. The aim of this research was to evaluate the oxidative stability of Choibá oil at 100°C ± 1°C with aeration (1150 mL air/min) supplemented with rosemary extract (Rosmarinus officinalis L.), at 1000 mg/L (RE1000) and 1500 mg/L (RE1500), and with BHT (200 mg/L) and from this results to evaluate the degradation kinetics and shelf-life of Choibá oil at 35°C, 45°C and 55°C without addition of antioxidants (Control) and with addition of best concentration of rosemary extract obtained from previous study. Progress in oil oxidation was measured through the extent of oxidation products: peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Results revealed that the addition of rosemary extract at 1500 mg/L significantly reduced de formation of hydroperoxides (PV), more than BHT. Through correlations between concentrations of antioxidant (including control without antioxidant) with peroxide values, the kinetics of degradation and shelf-life of Choibá oil with predictive models are evaluated in real time and accelerated (35°C, 45°C and 55°C) using the Arrhenius equation. In addition, the oxidation reactions of this oil follow a first order kinetic model for PV and zero order kinetic model for TBARS. The rate of formation of PV was dependent on the storage temperature, according to the Arrhenius equation with the activation energy of 4611.5071 J/mol for Control and 7409.5771 J/mol for RE1500 treatment. The result of TBARS didn’t adjust to Arrhenius model, thus measurement of malondialdehyde (MDA) wasn’t a useful parameter for shelf-life determination of Choibá oil.

Progression in the Oxidation Stability of MXenes

MXenes are under the spotlight due to their versatile physicochemical characteristics. Since their discovery in 2011, significant advancements have been achieved in their synthesis and application sectors. However, the spontaneous oxidation of MXenes, which is critical to its processing and product lifespan, has gotten less attention due to its chemical complexity and poorly understood oxidation mechanism. This perspective focuses on the oxidation stability of MXenes and addresses the most recent advancements in understanding and the possible countermeasures to limit the spontaneous oxidation of MXenes. A section is dedicated to the presently accessible methods for monitoring oxidation, with a discussion on the debatable oxidation mechanism and coherently operating factors that contribute to the complexity of MXenes oxidation. The current potential solutions for mitigating MXenes oxidation and the existing challenges are also discussed with prospects to prolong MXene's shelf-life storage and expand their application scope.

Theoretical and experimental study on the inhibition of jet fuel oxidation by diarylamine

Antioxidants addition is believed as a facile and effective way to improve jet fuel thermal oxidation stability.However,amine antioxidants,as one of the most important antioxidants,have not received sufficient attention in the field of jet fuel autoxidation yet.Herein,the inhibition efficiency and mechanism of decane and exo-tetrahydrodicyclopentadiene(THDCPD)oxidation by di-4-tert-butylphenylamine(diarylamine)was experimentally and theoretically investigated.The results show that diarylamine can significantly inhibit decane oxidation but is less efficient for THDCPD oxidation,which is attributed to the higher energy barrier of retro-carbonyl-ene reaction(rate-determining step)in THDCPD than that in decane during diarylamine regeneration.However,the addition of diarylamine will cause undesirable color change after accelerated oxidation and produce slightly more deposits during high-temperature thermal oxidative stress for both decane and THDCPD.The results provide significant implications for the future design of effective antioxidant additives for high-performance jet fuel.

Lipid oxidation in food science and nutritional health: A comprehensive review

Food provides abundant nutrients for human beings, but also has sensory functions and physiological regulation.Lipids are the main components of food as well as the important structural and functional components of cells.Nevertheless, lipids are easily oxidized by different ways, such as thermal oxidation and air oxidation. Lipidoxidation has adverse effects on food quality and human health. Therefore, efforts should be made to reduce lipidoxidation and improve its stability. This review focuses on important knowledge about lipid oxidation, includingthe concept of lipids and lipid oxidation, the main pathways and mechanisms of lipid oxidation, factors affectinglipid oxidation, strategies to improve the stability of lipid oxidation, and the recent research progress of lipidoxidation in food science and nutritional health.

Matrix-Material Fabrication Technique and Thermogravimetric Analysis of Banana Fiber Reinforced Polypropylene Composites

From the environmental consideration,it would be very interesting to use natural fibers such as banana,jute or coir as reinforcement materials instead of artificial fibers or any kind of synthetic materials.Natural fibers have many advantages over synthetic ones.Polypropylene banana fiber composites(PPBC)are prepared using untreated and alkali-treated banana fibers at 10-25%by weight of the fiber loading.The thermal properties of polypropylene natural fiber composites are very important for technological uses.Thermogravimetric measurements show that the incorporation of banana fiber into PP enhances the thermal stability of composites containing treated fibers,in comparison with untreated fibers.A composite of biodegradable polypropylene(PP)reinforced with short banana natural fibers was prepared by melt blending followed by a hot press molding system.The thermal properties of matrix materials were studied using thermogravimetric analyzers TGA units.It is observed that the introduction of short banana fibers slightly improved the thermo oxidative stability of PP-banana composites.Physical and chemical changes occurred through dehydration,phase transition,molecular orientation,crystallinity disruption,oxidation and decomposition,and incorporation of several functional groups.Systematic investigations of the thermal behavior of polymers in gas,vacuum or inert atmosphere give the knowledge of how change takes place in polymers.To understand such changes thermogravimetric analysis(TGA)and thermal analysis(TG)were performed.It is observed reinforcement of short banana fiber leads to little improvement in the thermooxidative stability of PPBC.Due to the enhancement of thermo-mechanical properties,such composites may be used as building materials namely roof materials,selling materials and many other engineering applications.

A rationale for the development of thermally stable nanostructured CeO_2-ZrO_2-containing mixed oxides

CeO2-ZeO2 solid solutions are extensively used as oxygen storage promoters in the current automotive three-way catalysts. High thermal stability of the textural properties is one of the most important requirements for practical application since temperatures up to 1273 K are easily experienced by these materials under real working conditions. In the present paper, we investigated how hydrothermal treatments applied to cakes of doped and undoped ZrO2-rich CeO2-ZrO2 precursors might improve the thermal stability of the final CeO2-ZrO2 solid solution. A rationale was developed that allowed to correlate the morphology of the hydrothermaUy treated cake with the thermal stability at 1273 K of the final product, which did not depend on the composition of the mixed oxides.

Processed beetroot(Beta vulgaris L.)as a natural antioxidant in mayonnaise:Effects on physical stability,texture and sensory attributes

The oxidative and physical stability of the reformulated mayonnaise with processed beetroot was investigated and compared with a control(mayonnaise without beetroot)and a commercially available product.Processing of beetroot had an impact on the structural integrity of the antioxidants present.Microwaving(960 W for 7 min)was advantageous for preserving the betalain and polyphenol content of beetroot compared to roasting(180◦C for 90 min)and boiling(100◦C for 30 min).The oxidative stability of mayonnaise samples was determined by Rancimat and the thiobarbituric(TBA)assay.The addition of microwaved beetroot significantly enhanced the oxidative stability of mayonnaise at the end of a storage period of 4 weeks(4◦C).Although no significant differences(P>0.05)were detected between the mayonnaise samples containing beetroot and the commercial control,the latter was less susceptible to oxidation during storage.The turbiscan stability index(TSI)revealed that the commercial mayonnaise was less prone to destabilization phenomena.All the textural parameters increased with the incorporation of beetroot.The sensory evaluation revealed that,with the exception of graininess and uniformity,most of the sensory attributes are preserved if not improved with the addition of beetroot.

Fast Evaluation Peanut Oil Quality by Synchronous Fluorescence Spectroscopy and Statistical Analysis

Peanut oil oxidation was to monitor and quantify combining synchronous fluorescence spectroscopy and chemometrics. Peanut oil was subjected to an accelerated oxidation testing. The spectral and related chemical indicators were caught during oxidation induce testing. Fluorescence spectra were gained for each sample with simultaneous excitation from 200 to 800 nm and the offsets (Δλ) of 10 to 180 nm during the oxidation process. The results showed the induce period (IP) of the peanut oil was 16.45 h. Parallel factor analysis (PARAFAC) was performed to select the best Δλ interval of 70 nm, which spectral data was the most suitable for interval partial least square (iPLS) and synergy interval PLS (siPLS) modeling and forecast. The study presented all interval selection methods had the better results than the global spectrum modelling. iPLS reached the best into 10 intervals with a ratio of prediction to deviation (RPD) of 2.10. siPLS that separated the whole spectrum into 15 intervals and combined the third intervals (282 to 320 nm, 362 to 400 nm, and 761 to 800 nm) had a ratio of RPD of 2.26. The results showed the optimal siPLS model performed a little better than iPLS. The established model lying on interval selection could improve the prediction accuracy. It could provide a quick, accurate method to monitor oil oxidation process.

Study of selective hydrogenation of biodiesel in a DBD plasma reactor

In order to achieve the selective hydrogenation of biodiesel at room temperature and under normal pressure,we researched the upgrading of soybean biodiesel using a dielectric-barrier discharge(DBD)reaction system.Using Raney-Ni as the hydrogenation catalyst,the effects of the operating parameters on the hydrogenation depth and the selectivity of biodiesel were systematically analyzed.The results show that the polyunsaturated components in soybean methyl ester were reduced by 57.04%,and that the polyunsaturated components were hydrogenated to monounsaturated components with a selectivity of 77.75%.Based on the gas chromatography and mass spectrometry(GC-MS)test results,we established a kinetic model for biodiesel hydrogenation.A comparison of the calculated and experimental results shows that the hydrogenation of the biodiesel can be described by a quasi first-order reaction model.The calculated reaction rate constants indicate that under DBD plasma reaction conditions,the hydrogenation of biodiesel has high selectivity for the formation of monounsaturated components.

Improving beef hamburger quality and fatty acid profiles through dietary manipulation and exploitation of fat depot heterogeneity

Background： Hamburger is the most consumed beef product in North America, but lacks in nutritional appeal due to its high fat content and high proportion of saturated fatty acids （SFA）. Objectives of the present study were to improve the FA profiles of hamburgers made with perirenal fat （PRF） and subcutaneous fat （SCF） when feeding steers different diets along with examining differences in sensory attributes and oxidative stability. Diets included a control diet containing 70：30 red clover silage： barley based concentrate, a diet containing sunflower-seed （SS） substituted for barley, and diets containing SS with 15% wheat dried distillers＇ grain with solubles （DDGS-15） or 30% DDGS （DDGS-30）. Hamburgers were made from triceps brachii and either PRF or SCF （80：20 w/w）. Results： Perirenal fat versus SCF hamburgers FA had 14.3% more （P 〈0.05） 18：0, 11.8% less cis （c）9-18：1 （P 〈0.05）, and 1.82% more total trdns （t）-18：1 mainly in the form of tl 1-18：1. During sensory evaluation, PRF versus SCF hamburgers had greater （P 〈0.05） mouth coating, but the difference was less than one panel unit. Examining effects of steer diet within PRF hamburgers, feeding the SS compared to the control diet increased （P 〈0.05） t-18：1 by 2.89% mainly in the form of tl 1-18：1, feeding DGGS-15 diet led to no further changes （P 〉0.05）, but feeding DDGS-30 diet reduced the proportions of （P 〈0.05） of t-18：1 chiefly tl 1-18：1. Feeding SS and DDGS diets had small but significant （P 〈0.05） effects on hamburger sensory attributes and oxidative stability. Conclusions： Feeding high-forage diets including SS and 15% DDGS, and taking advantage of the FA heterogeneity between fat depots offers an opportunity to differentially enhance beef hamburgers with 18：2n-6 biohydrogenation products （Le., t11-18：1） with potential human health benefits without compromising their sensory attributes and oxidative stability during retail display.

Effects of Soursop flowers(Annona muricata L.)extract on chemical changes of refined palm olein stored at frying temperature

In this study,the antioxidant activity of soursop flowers extract in delaying palm olein oxidation at frying temperature was assessed.The oil was supplemented with the extract at concentrations 200–1800 ppm,and stored in the oven at 180◦C for 6 days(4 h heating per day).Palm olein containing butylated hydroxytoluene(BHT)served as positive control while the same oil without antioxidant(Control)served as negative one,in order to monitor changes in oils.After each two heating days,oil samples were collected,and their chemical indexes were determined.Peroxide,para-anisidine,TOTOX,thiobarbituric acid and iodine values were the parameters evaluated.Additionally,the evolution of the fatty acid composition of each oil sample during the storage was assessed by gas-chromatography using a flame ionization detector(GC/FID).Generally,palm olein samples containing the natural extract have exhibited the lowest rate of oxidation,and were efficient in limiting the destruction of unsaturated fatty acids in oil at frying temperature.The order of effectiveness in inhibiting oil oxidation was the following:PO+AnM1800ppm>PO+AnM1400ppm>PO+AnM1000ppm>PO+An.M600ppm>PO+An.M200ppm>PO+BHT200ppm=Control.From these results,it can be concluded that soursop flowers are a potent sources of natural antioxidants for stabilization of palm olein.

Comparative Evaluation of the Thermal Aging of Solid Insulation in Mineral Oil and Methyl Ester of Palm Kernel Oil

The purpose of this work is to determine the impact of thermal aging on the dielectric and physicochemical properties of the oil/paper mixed insulation. We performed a comparative analysis of dielectric paper dipped in two cooling fluids: palm kernel oil methyl ester (MEPKO) and mineral oil (MO). Two types of dielectric paper were used: Thermally Upgraded Kraft paper (TUK) and Nomex-910 paper (NP-910). An accelerated aging test was realized at 110°C during a total of 96 hours. Samples of oil and paper were collected after 0, 48, 72 and 96 hours for analyses purposes. The analyses performed included the measurement of the Breakdown voltage (BDV) of the dielectric papers, the Total Acid Number (TAN) and the Decay Dissolved Products (DDP) of the liquid dielectrics. The BDV of NP-910 is greater than the BDV of TUK. Concerning the type of oil, the BDV of dielectric papers impregnated with MEPKO is greater than the BDV of similar papers impregnated with MO, indicating a better preservation of paper when dipped in methyl esters. The analyses of TAN and DDP revealed that Nomex-910 improves the oxidation stability of MO, but reduces the oxidation stability of MEPKO. These results prove that methyl esters can be used as a substitute to replace mineral oils in power transformers. Furthermore, they show that NP can be used mainly in areas of transformer where solid insulation is subjected to high thermal and electrical stress, and TUK other places where solid insulation is required. Such combination could assure money savings and a better preservation of the oil viscosity.

Composite Cathode Bi_(1.14)Sr_(0.43)O_(2.14)-Ag for Intermediate-temperature Solid Oxide Fuel Cells

Composites consisting of strontium stabilized bismuth oxide （Bi1.14Sr0.43O2.14, SSB） and silver were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria electrolyte. There were no chemical reactions between the two components. The microstructure of the interfaces between composite cathodes and Ce0.8Sm0.2O1.9 （SDC） electrolytes was examined by scanning electron microscopy （SEM）. Impedance spectroscopy measurements show that the performance of cathode fired at 700 ℃ is the best. When the content of Ag2O is 70 wt%, polarization resistance values for the SSB-Ag cathodes are as low as 0.2 Ωcm^2 at 700℃ and 0.29 Ωcm^2 at 650℃. These results are much smaller than some of other reported composite cathodes on doped ceria electrolyte and indicate that SSB-Ag composite is a potential cathode material for intermediate temperature SOFCs.